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  • 1.
    Ajdén, Per
    et al.
    Linköping University, Department of Management and Engineering, Mechanics .
    Backlund, Carl
    Linköping University, Department of Management and Engineering, Mechanics .
    Pilotmodeller till flygmekanisk simulator för JAS 39 Gripen2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Abstract

    SAAB has for a long time used user controlled pilot models in ARES. ARES is a simulation tool used in the desktop environment for simulations and calculations of the JAS 39 Gripen fighter and other aircraft. ARES stands for ”Aircraft Rigid body Engineering Simulation”. To work with these pilot models has been both time-consuming and inefficient. In this master thesis, new pilot models are developed, where parameters are automatically generated, this will result in that the user doesn’t have to put a lot of work into adjusting the gains for different manoeuvres. This is called gain scheduling.

    To make this possible, simple models of the aircraft were created at different points in the envelope. These models were then used to calculate optimal controllers using LQ-control and pole placement techniques. These models and controllers were then implemented in Simulink. Simulink was then used to test the controllers before they were implemented in ARES.

    Control in all modes except roll attitude and speed by throttle are based on LQ-control in pitch-, roll- and yaw-angular velocity. And through these angular velocities the other angles are controlled by simple controllers, who is generating a reference in angular velocity. The roll attitude controller is based on direct pole placement based upon desired damping and undamped natural frequency, and the speed controller is based upon a model of throttle positions in trimmed states.

    The new pilot models are usable to control:

    • Roll rate
    • Roll attitude
    • Pitch rate
    • Pitch attitude
    • Angle of attack
    • Load factor
    • Yaw attitude
    • Course angle
    • Climb angle
    • Mach number
    • Climb rate

    These controllers can be combined so that the aircraft can perform desired maneuvers.

  • 2.
    Albrektsson, Jörgen
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering. Volvo Construction Equipment, Eskilstuna, Sweden.
    Åslund, Jan
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Fuel Optimal Control of an Articulated Hauler Utilising a Human Machine Interface2019In: Smart Cities, Green Technologies, and Intelligent Transport Systems / [ed] Donnellan, Brian; Klein, Cornel; Helfert, Markus; Gusikhin, Oleg; Pascoal, António, Springer International Publishing , 2019, p. 190-208Conference paper (Refereed)
    Abstract [en]

    Utilising optimal control presents an opportunity to increase the fuel efficiency in an off-road transport mission conducted by an articulated hauler. A human machine interface (HMI) instructing the hauler operator to follow the fuel optimal vehicle speed trajectory has been developed and tested in real working conditions. The HMI implementation includes a Dynamic Programming based method to calculate the optimal vehicle speed and gear shift trajectories. Input to the optimisation algorithm is road related data such as distance, road inclination and rolling resistance. The road related data is estimated in a map module utilising an Extended Kalman Filter (EKF), a Rauch-Tung-Striebel smoother and a data fusion algorithm. Two test modes were compared: (1) The hauler operator tried to follow the optimal vehicle speed trajectory as presented in the HMI and (2) the operator was given a constant target speed to follow. The objective of the second test mode is to achieve an approximately equal cycle time as for the optimally controlled transport mission, hence, with similar productivity. A small fuel efficiency improvement was found when the human machine interface was used.

  • 3.
    Alegret, Guillem
    et al.
    MAN Diesel & Turbo, Copenhagen, Denmark.
    Llamas, Xavier
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Vejlgaard-Laursen, Morten
    MAN Diesel & Turbo, Copenhagen, Denmark.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Modeling of a Large Marine Two-Stroke Diesel Engine with Cylinder Bypass Valve and EGR System2015In: 10th IFAC Conference on Manoeuvring and Control of Marine Craft MCMC 2015: Copenhagen, 24–26 August 2015 / [ed] Roberto Galeazzi and Mogens Blanke, IFAC Papers Online, 2015, Vol. 48, p. 273-278Conference paper (Refereed)
    Abstract [en]

    A nonlinear mean value engine model (MVEM) of a two-stroke turbocharged marine diesel engine is developed, parameterized and validated against measurement data. The goal is to have a computationally fast and accurate engine model that captures the main dynamics and can be used in the development of control systems for the newly introduced EGR system. The tuning procedure used is explained, and the result is a six-state MVEM with seven control inputs that capture the main system dynamics.

  • 4.
    Andersson, Anders
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering. Statens väg- och transportforskningsinstitut (VTI), Trafik och trafikant,TRAF, Fordonsteknik och simulering, FTS, Linköping, Sweden.
    Distributed Moving Base Driving Simulators: Technology, Performance, and Requirements2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Development of new functionality and smart systems for different types of vehicles is accelerating with the advent of new emerging technologies such as connected and autonomous vehicles. To ensure that these new systems and functions work as intended, flexible and credible evaluation tools are necessary. One example of this type of tool is a driving simulator, which can be used for testing new and existing vehicle concepts and driver support systems. When a driver in a driving simulator operates it in the same way as they would in actual traffic, you get a realistic evaluation of what you want to investigate. Two advantages of a driving simulator are (1.) that you can repeat the same situation several times over a short period of time, and (2.) you can study driver reactions during dangerous situations that could result in serious injuries if they occurred in the real world. An important component of a driving simulator is the vehicle model, i.e., the model that describes how the vehicle reacts to its surroundings and driver inputs. To increase the simulator realism or the computational performance, it is possible to divide the vehicle model into subsystems that run on different computers that are connected in a network. A subsystem can also be replaced with hardware using so-called hardware-in-the-loop simulation, and can then be connected to the rest of the vehicle model using a specified interface. The technique of dividing a model into smaller subsystems running on separate nodes that communicate through a network is called distributed simulation.

    This thesis investigates if and how a distributed simulator design might facilitate the maintenance and new development required for a driving simulator to be able to keep up with the increasing pace of vehicle development. For this purpose, three different distributed simulator solutions have been designed, built, and analyzed with the aim of constructing distributed simulators, including external hardware, where the simulation achieves the same degree of realism as with a traditional driving simulator. One of these simulator solutions has been used to create a parameterized powertrain model that can be configured to represent any of a number of different vehicles. Furthermore, the driver's driving task is combined with the powertrain model to monitor deviations. After the powertrain model was created, subsystems from a simulator solution and the powertrain model have been transferred to a Modelica environment. The goal is to create a framework for requirement testing that guarantees sufficient realism, also for a distributed driving simulation.

    The results show that the distributed simulators we have developed work well overall with satisfactory performance. It is important to manage the vehicle model and how it is connected to a distributed system. In the distributed driveline simulator setup, the network delays were so small that they could be ignored, i.e., they did not affect the driving experience. However, if one gradually increases the delays, a driver in the distributed simulator will change his/her behavior. The impact of communication latency on a distributed simulator also depends on the simulator application, where different usages of the simulator, i.e., different simulator studies, will have different demands. We believe that many simulator studies could be performed using a distributed setup. One issue is how modifications to the system affect the vehicle model and the desired behavior. This leads to the need for methodology for managing model requirements. In order to detect model deviations in the simulator environment, a monitoring aid has been implemented to help notify test managers when a model behaves strangely or is driven outside of its validated region. Since the availability of distributed laboratory equipment can be limited, the possibility of using Modelica (which is an equation-based and object-oriented programming language) for simulating subsystems is also examined. Implementation of the model in Modelica has also been extended with requirements management, and in this work a framework is proposed for automatically evaluating the model in a tool.

    List of papers
    1. Vehicle Powertrain Test Bench Co-Simulation with a Moving Base Simulator Using a Pedal Robot
    Open this publication in new window or tab >>Vehicle Powertrain Test Bench Co-Simulation with a Moving Base Simulator Using a Pedal Robot
    2013 (English)In: SAE International Journal of Passenger Cars - Electronic and Electrical Systems, ISSN 1946-4614, E-ISSN 1946-4622, Vol. 6, no 1, p. 169-179Article in journal (Refereed) Published
    Abstract [en]

    To evaluate driver perception of a vehicle powertrain a moving base simulator is a well-established technique. We are connecting the moving base simulator Sim III, at the Swedish National Road and Transport Research Institute with a newly built chassis dynamometer at Vehicular Systems, Linköping University. The purpose of the effort is to enhance fidelity of moving base simulators by letting drivers experience an actual powertrain. At the same time technicians are given a new tool for evaluating powertrain solutions in a controlled environment. As a first step the vehicle model from the chassis dynamometer system has been implemented in Sim III. Interfacing software was developed and an optical fiber covering the physical distance of 500 m between the facilities is used to connect the systems. Further, a pedal robot has been developed that uses two linear actuators pressing the accelerator and brake pedals. The pedal robot uses feedback loops on accelerator position or brake cylinder pressure and is controlled via an UDP interface. Results from running the complete setup showed expected functionality and we are successful in performing a driving mission based on real road topography data. Vehicle acceleration and general driving feel was perceived as realistic by the test subjects while braking still needs improvements. The pedal robot construction enables use of a large set of cars available on the market and except for mounting the brake pressure sensor the time to switch vehicle is approximately 30 minutes.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-92215 (URN)10.4271/2013-01-0410 (DOI)
    Available from: 2013-05-08 Created: 2013-05-08 Last updated: 2019-04-28Bibliographically approved
    2. A Driving Simulation Platform using Distributed Vehicle Simulators and HLA
    Open this publication in new window or tab >>A Driving Simulation Platform using Distributed Vehicle Simulators and HLA
    Show others...
    2015 (English)In: Proceedings of the DSC 2015 Europe: Driving Simulation Conference & Exhibition / [ed] Heinrich Bülthoff, Andras Kemeny and Paolo Pretto, 2015, p. 123-130Conference paper, Published paper (Refereed)
    Abstract [en]

    Modern vehicles are complex systems consisting of an increasing large multitude of components that operate together. While functional verification on individual components is important, it is also important to test components within a driving environment, both from a functional perspective and from a driver perspective. One proven way for testing is vehicle simulators and in this work the main goals have been to increase flexibility and scalability by introducing a distributed driving simulator platform.

    As an example, consider a workflow where a developer can go from a desktop simulation to an intermediate driving simulator to a high fidelity driving simulator with Hardware-In-the-Loop systems close to a finished vehicle in an easy way. To accomplish this, a distributed simulation architecture was designed and implemented that divides a driving simulator environment into four major entities with well-defined interfaces, using HLA as the method of communication. This platform was evaluated on two aspects, flexibility/scalability and timing performance. Results show that increased flexibility and scalability was achieved when using a distributed simulation platform. It is also shown that latency was only slightly increased when using HLA.

    Keywords
    Test, Vehicle, Engine, Performance, Simulator (driving), Computer
    National Category
    Computer Systems
    Research subject
    90 Road: Vehicles and vehicle technology, 911 Road: Components of the vehicle; 90 Road: Vehicles and vehicle technology, 96 Road: Vehicle operating and management
    Identifiers
    urn:nbn:se:liu:diva-136153 (URN)9783981309935 (ISBN)
    Conference
    Driving Simulation Conference 2015. 16-18 september 2015, Tübingen, Germany
    Available from: 2016-01-11 Created: 2017-03-31 Last updated: 2019-04-28Bibliographically approved
    3. Testing cooperative intelligent transport systems in distributed simulators
    Open this publication in new window or tab >>Testing cooperative intelligent transport systems in distributed simulators
    Show others...
    2019 (English)In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 65, p. 206-216Article in journal (Refereed) Published
    Abstract [en]

    Simulation is often used as a technique to test and evaluate systems, as it provides a cost-efficient and safe alternative for testing and evaluation. A combination of simulators can be used to create high-fidelity and realistic test scenarios, especially when the systems-under-test are complex. An example of such complex systems is Cooperative Intelligent Transport Systems (C-ITS), which include many actors that are connected to each other via wireless communication in order to interact and cooperate. The majority of the actors in the systems are vehicles equipped with wireless communication modules, which can range from fully autonomous vehicles to manually driven vehicles. In order to test and evaluate C-ITS, this paper presents a distributed simulation framework that consists of (a) a moving base driving simulator; (b) a real-time vehicle simulator; and (c) network and traffic simulators. We present our approach for connecting and co-simulating the simulators. We report on limitation and performance that this simulation framework can achieve. Lastly, we discuss potential benefits and feasibility of using the simulation framework for testing of C-ITS.

    Place, publisher, year, edition, pages
    Elsevier, 2019
    Keywords
    Cooperative intelligent transportation systems, Hardware-in-the-loop, Network simulator, Traffic simulator, Moving base driving simulator
    National Category
    Vehicle Engineering Computer Systems
    Identifiers
    urn:nbn:se:liu:diva-159824 (URN)10.1016/j.trf.2019.07.020 (DOI)
    Available from: 2019-08-22 Created: 2019-08-22 Last updated: 2019-08-22Bibliographically approved
    4. Parameterization procedure of a powertrain model for a driving simulator
    Open this publication in new window or tab >>Parameterization procedure of a powertrain model for a driving simulator
    2016 (English)In: Advances in Transportation Studies, ISSN 1824-5463, Vol. 1, p. 99-112Article in journal (Refereed) Published
    Abstract [en]

    The automotive industry is facing a major challenge to reduce environmental impacts. As a consequence, the increasing diversity of powertrain configurations put a demand on testing and evaluation procedures. One of the key tools for this purpose is simulators. In this paper a powertrain model and a procedure for parameterizing it, using chassis dynamometers and a developed pedal robot are presented. The parameterizing procedure uses the on-board diagnostics of the car and does not require any additional invasive sensors.

    Thus, the developed powertrain model and parameterization procedure provide a rapid non- invasive way of modelling powertrains of test cars. The parameterizing procedure has been used to model a front wheel drive Golf V with a 1.4L multi-fuel engine and a manual gearbox. The achieved results show a good match between simulation results and test data. The powertrain model has also been tested in real-time in a driving simulator.

    Place, publisher, year, edition, pages
    Aracne editrice, 2016
    Keywords
    Motor, Test, Characteristics, Simulation
    National Category
    Vehicle Engineering
    Research subject
    90 Road: Vehicles and vehicle technology, 911 Road: Components of the vehicle
    Identifiers
    urn:nbn:se:liu:diva-156538 (URN)10.4399/978885489179109 (DOI)2-s2.0-84982994768 (Scopus ID)
    Available from: 2019-04-26 Created: 2019-04-26 Last updated: 2019-05-03Bibliographically approved
    5. Vehicle model quality framework for moving base driving simulators, a powertrain model example
    Open this publication in new window or tab >>Vehicle model quality framework for moving base driving simulators, a powertrain model example
    2018 (English)In: International Journal of Vehicle Systems Modelling and Testing, ISSN 1745-6436, E-ISSN 1745-6444, Vol. 13, no 2, p. 93-108Article in journal (Refereed) Published
    Abstract [en]

    Moving base driving simulators, with an enclosed human driver, are often used to study driver-vehicle interaction or driver behaviour. Reliable results from such a driving simulator study strongly depend on the perceived realism by the driver in the performed driving task. Assuring sufficient fidelity for a vehicle dynamics model during a driving task is currently to a large degree a manual task. Focus here is to automate this process by employing a framework using collected driving data for detection of model quality for different driving tasks. Using this framework, a powertrain model credibility is predicted and assessed. Results show that chosen powertrain model is accurate enough for a driving scenario on rural roads/motorway, but need improvements for city driving. This was expected, considering the complexity of the vehicle dynamics model, and it was accurately captured by the proposed framework which includes real-time information to the simulator operator.

    Place, publisher, year, edition, pages
    InderScience Publishers, 2018
    Keywords
    vehicle dynamics model, driving simulator, driving task, quality framework, domain of validity, domain of operation, powertrain model
    National Category
    Computer Systems Vehicle Engineering
    Identifiers
    urn:nbn:se:liu:diva-156544 (URN)10.1504/IJVSMT.2018.098330 (DOI)2-s2.0-85063100727 (Scopus ID)
    Available from: 2019-04-26 Created: 2019-04-26 Last updated: 2019-05-03Bibliographically approved
    6. Models for Distributed Real-Time Simulation in a Vehicle Co-Simulator Setup
    Open this publication in new window or tab >>Models for Distributed Real-Time Simulation in a Vehicle Co-Simulator Setup
    2013 (English)In: Proceedings of the 5th International Workshop on Equation-Based Object-Oriented Modeling Languages and Tools; April 19, University of Nottingham, Nottingham, UK / [ed] Henrik Nilsson, Linköping: Linköping University Electronic Press, 2013, Vol. 84, p. 131-139Conference paper, Published paper (Refereed)
    Abstract [en]

    A car model in Modelica has been developed to be used in a new setup for distributed real-time simulation where a moving base car simulator is connected with a real car in a chassis dynamometer via a 500m fiber optic communication link. The new co-simulator set-up can be used in a number of configurations where hardware in the loop can be interchanged with software in the loop. The models presented in this paper are the basic blocks chosen for modeling the system in the context of a distributed real-time simulation; estimating parameters for the powertrain model; the choice of numeric solver; and the interaction with the solver for real-time properties.

    Place, publisher, year, edition, pages
    Linköping: Linköping University Electronic Press, 2013
    Series
    Linköping Electronic Conference Proceedings, ISSN 1650-3686, E-ISSN 1650-3740 ; 84
    Keywords
    Modelica; real-time; distributed; communications link
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:liu:diva-118994 (URN)978-91-7519-621-3 (ISBN)978-91-7519-617-6 (ISBN)
    Conference
    The 5th International Workshop on Equation-Based Object-Oriented Modeling Languages and Tools, April 19, University of Nottingham, Nottingham; UK
    Available from: 2015-06-05 Created: 2015-06-05 Last updated: 2019-04-28Bibliographically approved
    7. Powertrain Model Assessment for Different Driving Tasks through Requirement Verification
    Open this publication in new window or tab >>Powertrain Model Assessment for Different Driving Tasks through Requirement Verification
    2018 (English)In: The 9th EUROSIM Congress on Modelica and Simulation, 2018, p. 721-727Conference paper, Published paper (Refereed)
    Abstract [en]

    For assessing whether a system model is a good candidate for a particular simulation scenario or choosing the best system model between multiple design alternatives it is important to be able to evaluate the suitability of the system model. In this paper we present a methodology based on finite state machine requirements verifying system behaviour in a Modelica environment where the intended system model usage is within a moving base driving simulator. A use case illustrate the methodology with a Modelica powertrain system model using replaceable components and measured data from a Golf V. The achieved results show the importance of context of requirements and how users are assisted in finding system model issues. 

    Series
    Linköping Electronic Conference Proceedings, ISSN 1650-3686, E-ISSN 1650-3740 ; 142
    Keywords
    system model assessment, requirement modelling, Modelica, finite state machine, powertrain validations
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:liu:diva-156540 (URN)10.3384/ecp17142721 (DOI)978-91-7685-399-3 (ISBN)
    Conference
    EUROSIM 2016
    Available from: 2019-04-26 Created: 2019-04-26 Last updated: 2019-05-13
  • 5.
    Andersson, Anders
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering. Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Extensions for Distributed Moving Base Driving Simulators2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Modern vehicles are complex systems. Different design stages for such a complex system include evaluation using models and submodels, hardware-in-the-loop systems and complete vehicles. Once a vehicle is delivered to the market evaluation continues by the public. One kind of tool that can be used during many stages of a vehicle lifecycle is driving simulators.

    The use of driving simulators with a human driver is commonly focused on driver behavior. In a high fidelity moving base driving simulator it is possible to provide realistic and repetitive driving situations using distinctive features such as: physical modelling of driven vehicle, a moving base, a physical cabin interface and an audio and visual representation of the driving environment. A desired but difficult goal to achieve using a moving base driving simulator is to have behavioral validity. In other words, \A driver in a moving base driving simulator should have the same driving behavior as he or she would have during the same driving task in a real vehicle.".

    In this thesis the focus is on high fidelity moving base driving simulators. The main target is to improve the behavior validity or to maintain behavior validity while adding complexity to the simulator. One main assumption in this thesis is that systems closer to the final product provide better accuracy and are perceived better if properly integrated. Thus, the approach in this thesis is to try to ease incorporation of such systems using combinations of the methods hardware-in-the-loop and distributed simulation. Hardware-in-the-loop is a method where hardware is interfaced into a software controlled environment/simulation. Distributed simulation is a method where parts of a simulation at physically different locations are connected together. For some simulator laboratories distributed simulation is the only feasible option since some hardware cannot be moved in an easy way.

    Results presented in this thesis show that a complete vehicle or hardware-in-the-loop test laboratory can successfully be connected to a moving base driving simulator. Further, it is demonstrated that using a framework for distributed simulation eases communication and integration due to standardized interfaces. One identified potential problem is complexity in interface wrappers when integrating hardware-in-the-loop in a distributed simulation framework. From this aspect, it is important to consider the model design and the intersections between software and hardware models. Another important issue discussed is the increased delay in overhead time when using a framework for distributed simulation.

    List of papers
    1. Vehicle Powertrain Test Bench Co-Simulation with a Moving Base Simulator Using a Pedal Robot
    Open this publication in new window or tab >>Vehicle Powertrain Test Bench Co-Simulation with a Moving Base Simulator Using a Pedal Robot
    2013 (English)In: SAE International Journal of Passenger Cars - Electronic and Electrical Systems, ISSN 1946-4614, E-ISSN 1946-4622, Vol. 6, no 1, p. 169-179Article in journal (Refereed) Published
    Abstract [en]

    To evaluate driver perception of a vehicle powertrain a moving base simulator is a well-established technique. We are connecting the moving base simulator Sim III, at the Swedish National Road and Transport Research Institute with a newly built chassis dynamometer at Vehicular Systems, Linköping University. The purpose of the effort is to enhance fidelity of moving base simulators by letting drivers experience an actual powertrain. At the same time technicians are given a new tool for evaluating powertrain solutions in a controlled environment. As a first step the vehicle model from the chassis dynamometer system has been implemented in Sim III. Interfacing software was developed and an optical fiber covering the physical distance of 500 m between the facilities is used to connect the systems. Further, a pedal robot has been developed that uses two linear actuators pressing the accelerator and brake pedals. The pedal robot uses feedback loops on accelerator position or brake cylinder pressure and is controlled via an UDP interface. Results from running the complete setup showed expected functionality and we are successful in performing a driving mission based on real road topography data. Vehicle acceleration and general driving feel was perceived as realistic by the test subjects while braking still needs improvements. The pedal robot construction enables use of a large set of cars available on the market and except for mounting the brake pressure sensor the time to switch vehicle is approximately 30 minutes.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-92215 (URN)10.4271/2013-01-0410 (DOI)
    Available from: 2013-05-08 Created: 2013-05-08 Last updated: 2019-04-28Bibliographically approved
    2. Models for Distributed Real-Time Simulation in a Vehicle Co-Simulator Setup
    Open this publication in new window or tab >>Models for Distributed Real-Time Simulation in a Vehicle Co-Simulator Setup
    2013 (English)In: Proceedings of the 5th International Workshop on Equation-Based Object-Oriented Modeling Languages and Tools; April 19, University of Nottingham, Nottingham, UK / [ed] Henrik Nilsson, Linköping: Linköping University Electronic Press, 2013, Vol. 84, p. 131-139Conference paper, Published paper (Refereed)
    Abstract [en]

    A car model in Modelica has been developed to be used in a new setup for distributed real-time simulation where a moving base car simulator is connected with a real car in a chassis dynamometer via a 500m fiber optic communication link. The new co-simulator set-up can be used in a number of configurations where hardware in the loop can be interchanged with software in the loop. The models presented in this paper are the basic blocks chosen for modeling the system in the context of a distributed real-time simulation; estimating parameters for the powertrain model; the choice of numeric solver; and the interaction with the solver for real-time properties.

    Place, publisher, year, edition, pages
    Linköping: Linköping University Electronic Press, 2013
    Series
    Linköping Electronic Conference Proceedings, ISSN 1650-3686, E-ISSN 1650-3740 ; 84
    Keywords
    Modelica; real-time; distributed; communications link
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:liu:diva-118994 (URN)978-91-7519-621-3 (ISBN)978-91-7519-617-6 (ISBN)
    Conference
    The 5th International Workshop on Equation-Based Object-Oriented Modeling Languages and Tools, April 19, University of Nottingham, Nottingham; UK
    Available from: 2015-06-05 Created: 2015-06-05 Last updated: 2019-04-28Bibliographically approved
    3. A Driving Simulation Platform using Distributed Vehicle Simulators and HLA
    Open this publication in new window or tab >>A Driving Simulation Platform using Distributed Vehicle Simulators and HLA
    Show others...
    2015 (English)In: Proceedings of the DSC 2015 Europe: Driving Simulation Conference & Exhibition / [ed] Heinrich Bülthoff, Andras Kemeny and Paolo Pretto, 2015, p. 123-130Conference paper, Published paper (Refereed)
    Abstract [en]

    Modern vehicles are complex systems consisting of an increasing large multitude of components that operate together. While functional verification on individual components is important, it is also important to test components within a driving environment, both from a functional perspective and from a driver perspective. One proven way for testing is vehicle simulators and in this work the main goals have been to increase flexibility and scalability by introducing a distributed driving simulator platform.

    As an example, consider a workflow where a developer can go from a desktop simulation to an intermediate driving simulator to a high fidelity driving simulator with Hardware-In-the-Loop systems close to a finished vehicle in an easy way. To accomplish this, a distributed simulation architecture was designed and implemented that divides a driving simulator environment into four major entities with well-defined interfaces, using HLA as the method of communication. This platform was evaluated on two aspects, flexibility/scalability and timing performance. Results show that increased flexibility and scalability was achieved when using a distributed simulation platform. It is also shown that latency was only slightly increased when using HLA.

    Keywords
    Test, Vehicle, Engine, Performance, Simulator (driving), Computer
    National Category
    Computer Systems
    Research subject
    90 Road: Vehicles and vehicle technology, 911 Road: Components of the vehicle; 90 Road: Vehicles and vehicle technology, 96 Road: Vehicle operating and management
    Identifiers
    urn:nbn:se:liu:diva-136153 (URN)9783981309935 (ISBN)
    Conference
    Driving Simulation Conference 2015. 16-18 september 2015, Tübingen, Germany
    Available from: 2016-01-11 Created: 2017-03-31 Last updated: 2019-04-28Bibliographically approved
  • 6.
    Andersson, Anders
    et al.
    VTI, Swedish National Road and Transport Research Institute, Linköping, Sweden.
    Kharrazi, Sogol
    VTI, Swedish National Road and Transport Research Institute, Linköping, Sweden.
    Vehicle model quality framework for moving base driving simulators, a powertrain model example2018In: International Journal of Vehicle Systems Modelling and Testing, ISSN 1745-6436, E-ISSN 1745-6444, Vol. 13, no 2, p. 93-108Article in journal (Refereed)
    Abstract [en]

    Moving base driving simulators, with an enclosed human driver, are often used to study driver-vehicle interaction or driver behaviour. Reliable results from such a driving simulator study strongly depend on the perceived realism by the driver in the performed driving task. Assuring sufficient fidelity for a vehicle dynamics model during a driving task is currently to a large degree a manual task. Focus here is to automate this process by employing a framework using collected driving data for detection of model quality for different driving tasks. Using this framework, a powertrain model credibility is predicted and assessed. Results show that chosen powertrain model is accurate enough for a driving scenario on rural roads/motorway, but need improvements for city driving. This was expected, considering the complexity of the vehicle dynamics model, and it was accurately captured by the proposed framework which includes real-time information to the simulator operator.

  • 7.
    Andersson, Anders
    et al.
    Statens väg- och transportforskningsinstitut, Fordonsteknik och simulering, FTS, Linköping, Sweden.
    Kharrazi, Sogol
    Statens väg- och transportforskningsinstitut, Fordonsteknik och simulering, FTS, Linköping, Sweden.
    Lind, Simon
    Statens väg- och transportforskningsinstitut, Fordonsteknik och simulering, FTS, Linköping, Sweden.
    Myklebust, Andreas
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Parameterization procedure of a powertrain model for a driving simulator2016In: Advances in Transportation Studies, ISSN 1824-5463, Vol. 1, p. 99-112Article in journal (Refereed)
    Abstract [en]

    The automotive industry is facing a major challenge to reduce environmental impacts. As a consequence, the increasing diversity of powertrain configurations put a demand on testing and evaluation procedures. One of the key tools for this purpose is simulators. In this paper a powertrain model and a procedure for parameterizing it, using chassis dynamometers and a developed pedal robot are presented. The parameterizing procedure uses the on-board diagnostics of the car and does not require any additional invasive sensors.

    Thus, the developed powertrain model and parameterization procedure provide a rapid non- invasive way of modelling powertrains of test cars. The parameterizing procedure has been used to model a front wheel drive Golf V with a 1.4L multi-fuel engine and a manual gearbox. The achieved results show a good match between simulation results and test data. The powertrain model has also been tested in real-time in a driving simulator.

  • 8.
    Andersson, Håkan
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    A Co-Simulation Approach for Hydraulic Percussion Units2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This Licentiate of Engineering thesis concerns modelling and simulation of hydraulic percussion units. These units are often found in equipment for breaking or drilling in rock and concrete, and are also often driven by oil hydraulics, in which complex fluid-structure couplings are essential for their operation.

    Current methodologies used today when developing hydraulic percussion units are based on decoupled analyses, which are not correctly capturing the important coupled mechanisms. Hence, an efficient method for coupled simulations is of high importance, since these mechanisms are critical for the function of these units. Therefore, a co-simulation approach between a 1D system simulation model representing the fluid system and a structural 3D FE-model is proposed.

    This approach is presented in detail, implemented for two well-known simulation tools and evaluated for a simple but relevant model. The Hopsan simulation tool was used for the fluid system and the FE-simulation software LS-DYNA was used for the structural mechanics simulation. The co-simulation interface was implemented using the Functional Mock-up Interface-standard.

    The approach was further developed to also incorporate multiple components for coupled simulations. This was considered necessary when models for the real application are to be developed. The use of two components for co-simulation was successfully evaluated for two models, one using the simple rigid body representation, and a second where linear elastic representations of the structural material were implemented.

    An experimental validation of the co-simulation approach applied to an existing hydraulic hammer was performed. Experiments on the hydraulic hammer were performed using an in-house test rig, and responses were registered at four different running conditions. The co-simulation model was developed using the same approach as before. The corresponding running conditions were simulated and the responses were successfully validated against the experiments. A parameter study was also performed involving two design parameters with the objective to evaluate the effects of a parameter change.

    This thesis consists of two parts, where Part I gives an introduction to the application, the simulation method and the implementation, while Part II consists of three papers from this project.

    List of papers
    1. A co-simulation method for system-level simulation of fluid-structure couplings in hydraulic percussion units
    Open this publication in new window or tab >>A co-simulation method for system-level simulation of fluid-structure couplings in hydraulic percussion units
    Show others...
    2017 (English)In: Engineering with Computers, ISSN 0177-0667, E-ISSN 1435-5663, Vol. 33, no 2, p. 317-333Article in journal (Refereed) Published
    Abstract [en]

    This paper addresses a co-simulation method for fluid power driven machinery equipment, i.e. oil hydraulic machinery. In these types of machinery, the fluid-structure interaction affects the end-product performance to a large extent, hence an efficient co-simulation method is of high importance. The proposed method is based on a 1D system model representing the fluid components of the hydraulic machinery, within which structural 3D Finite Element (FE) models can be incorporated for detailed simulation of specific sub-models or complete structural assemblies. This means that the fluid system simulation will get a more accurate structural response, and that the structural simulation will get more correct fluid loads at every time step, compared to decoupled analysis. Global system parameters such as fluid flow, performance and efficiency can be evaluated from the 1D system model simulation results. From the 3D FE-models, it is possible to evaluate displacements, stresses and strains to be used in stress analysis, fatigue evaluation, acoustic analysis, etc. The method has been implemented using two well-known simulation tools for fluid power system simulations and FE-simulations, respectively, where the interface between the tools is realised by use of the Functional Mock-up Interface standard. A simple but relevant model is used to validate the method.

    Place, publisher, year, edition, pages
    SPRINGER, 2017
    Keywords
    Co-simulation; Fluid-structure coupling; System simulation; Functional mock-up interface; Fluid power machinery; Transmission line modelling
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:liu:diva-136875 (URN)10.1007/s00366-016-0476-8 (DOI)000398468100012 ()
    Note

    Funding Agencies|Atlas Copco Construction Tools

    Available from: 2017-04-30 Created: 2017-04-30 Last updated: 2018-09-11
    2. System level co-simulation of a control valve and hydraulic cylinder circuit in a hydraulic percussion unit
    Open this publication in new window or tab >>System level co-simulation of a control valve and hydraulic cylinder circuit in a hydraulic percussion unit
    Show others...
    2017 (English)In: Proceedings of 15:th Scandinavian International Conference on Fluid Power, June 7-9, 2017, Linköping, Sweden / [ed] Petter Krus, Liselott Ericson and Magnus Sethson, Linköping: Linköping University Electronic Press, 2017, Vol. 144, p. 225-235Conference paper, Published paper (Refereed)
    Abstract [en]

    In this study a previously developed co-simulation method that is based on a 1D system model representing the fluid components of a hydraulic machinery, within which structural 3D Finite Element (FE) models can be incorporated for detailed simulation of specific sub-models or complete structural assemblies, is further developed. The fluid system model consists of ordinary differential equation sub-models that are computationally very inexpensive, but still represents the fluid dynamics very well. The co-simulation method has been shown to work very well for a simple model representing a hydraulic driven machinery. A more complex model was set up in this work, in which two cylinders in the hydraulic circuit were evaluated. Such type of models, including both the main piston and control valves, are necessary as they represent the real application to a further extent than the simple model, of only one cylinder. Two models have been developed and evaluated, from the simple rigid body representation of the structural mechanics model, to the more complex model using linear elastic representation. The 3D FE-model facilitates evaluation of displacements, stresses, and strains on a local level of the model. The results can be utilised for fatigue assessment, wear analysis and for predictions of noise radiation.

    Place, publisher, year, edition, pages
    Linköping: Linköping University Electronic Press, 2017
    Series
    Linköping Electronic Conference Proceedings, ISSN 1650-3686, E-ISSN 1650-3740 ; 144
    Keywords
    Co-simulation, Fluid-structure coupling, System simulation, Functional mockup interface, Fluid power machinery, Transmission line modelling
    National Category
    Applied Mechanics Vehicle Engineering Control Engineering
    Identifiers
    urn:nbn:se:liu:diva-151015 (URN)10.3384/ecp17144225 (DOI)9789176853696 (ISBN)
    Conference
    15th Scandinavian International Conference on Fluid Power, June 7-9, 2017, Linköping, Sweden
    Available from: 2018-09-11 Created: 2018-09-11 Last updated: 2018-09-11Bibliographically approved
  • 9.
    Andersson, Håkan
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Hilding, Daniel
    DYNAmore Nordic AB, Brigadgatan 5, 587 58 Linköping, Sweden.
    Schill, Mikael
    DYNAmore Nordic AB, Brigadgatan 5, 587 58 Linköping, Sweden.
    Leidermark, Daniel
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    System level co-simulation of a control valve and hydraulic cylinder circuit in a hydraulic percussion unit2017In: Proceedings of 15:th Scandinavian International Conference on Fluid Power, June 7-9, 2017, Linköping, Sweden / [ed] Petter Krus, Liselott Ericson and Magnus Sethson, Linköping: Linköping University Electronic Press, 2017, Vol. 144, p. 225-235Conference paper (Refereed)
    Abstract [en]

    In this study a previously developed co-simulation method that is based on a 1D system model representing the fluid components of a hydraulic machinery, within which structural 3D Finite Element (FE) models can be incorporated for detailed simulation of specific sub-models or complete structural assemblies, is further developed. The fluid system model consists of ordinary differential equation sub-models that are computationally very inexpensive, but still represents the fluid dynamics very well. The co-simulation method has been shown to work very well for a simple model representing a hydraulic driven machinery. A more complex model was set up in this work, in which two cylinders in the hydraulic circuit were evaluated. Such type of models, including both the main piston and control valves, are necessary as they represent the real application to a further extent than the simple model, of only one cylinder. Two models have been developed and evaluated, from the simple rigid body representation of the structural mechanics model, to the more complex model using linear elastic representation. The 3D FE-model facilitates evaluation of displacements, stresses, and strains on a local level of the model. The results can be utilised for fatigue assessment, wear analysis and for predictions of noise radiation.

  • 10.
    Anund, Anna
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Rehabilitation Medicine. Swedish National Rd and Transport Research Institute, Linkoping, Sweden.
    Ihlstrom, Jonas
    Swedish National Rd and Transport Research Institute, Linkoping, Sweden.
    Fors, Carina
    Swedish National Rd and Transport Research Institute, Linkoping, Sweden.
    Kecklund, Göran
    Stockholm University, Sweden.
    Filtness, Ashleigh
    Queensland University of Technology, Australia.
    Factors associated with self-reported driver sleepiness and incidents in city bus drivers2016In: Industrial Health, ISSN 0019-8366, E-ISSN 1880-8026, Vol. 54, no 4, p. 337-346Article in journal (Refereed)
    Abstract [en]

    Driver fatigue has received increased attention during recent years and is now considered to be a major contributor to approximately 15-30% of all crashes. However, little is known about fatigue in city bus drivers. It is hypothesized that city bus drivers suffer from sleepiness, which is due to a combination of working conditions, lack of health and reduced sleep quantity and quality. The overall aim with the current study is to investigate if severe driver sleepiness, as indicated by subjective reports of having to fight sleep while driving, is a problem for city based bus drivers in Sweden and if so, to identify the determinants related to working conditions, health and sleep which contribute towards this. The results indicate that driver sleepiness is a problem for city bus drivers, with 19% having to fight to stay awake while driving the bus 2-3 times each week or more and nearly half experiencing this at least 2-4 times per month. In conclusion, severe sleepiness, as indicated by having to fight sleep during driving, was common among the city bus drivers. Severe sleepiness correlated with fatigue related safety risks, such as near crashes.

  • 11.
    Aramrattana, Maytheewat
    et al.
    The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Andersson, Anders
    The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Reichenberg, Frida
    RISE Viktoria, Lindholmen Science Park, Lindholmspiren 3A, Gothenburg, Sweden.
    Mellegård, Niklas
    RISE Viktoria, Lindholmen Science Park, Lindholmspiren 3A, Gothenburg, Sweden.
    Burden, Håkan
    RISE Viktoria, Lindholmen Science Park, Lindholmspiren 3A, Gothenburg, Sweden.
    Testing cooperative intelligent transport systems in distributed simulators2019In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 65, p. 206-216Article in journal (Refereed)
    Abstract [en]

    Simulation is often used as a technique to test and evaluate systems, as it provides a cost-efficient and safe alternative for testing and evaluation. A combination of simulators can be used to create high-fidelity and realistic test scenarios, especially when the systems-under-test are complex. An example of such complex systems is Cooperative Intelligent Transport Systems (C-ITS), which include many actors that are connected to each other via wireless communication in order to interact and cooperate. The majority of the actors in the systems are vehicles equipped with wireless communication modules, which can range from fully autonomous vehicles to manually driven vehicles. In order to test and evaluate C-ITS, this paper presents a distributed simulation framework that consists of (a) a moving base driving simulator; (b) a real-time vehicle simulator; and (c) network and traffic simulators. We present our approach for connecting and co-simulating the simulators. We report on limitation and performance that this simulation framework can achieve. Lastly, we discuss potential benefits and feasibility of using the simulation framework for testing of C-ITS.

  • 12.
    Baer, Katharina
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Design Study and Parameter Optimization for a Light-Weight Series Hydraulic Hybrid Vehicle2015Conference paper (Refereed)
    Abstract [en]

    Hydraulic hybrid drives are one potential way of improving the fuel efficiency of vehicles, including the possi-bility of recuperating braking energy in a hydraulic accumulator. The high power density of fluid power is mainly advantageous for heavy vehicles, or duty cycles characterized with frequent braking and acceleration. For smaller vehicles, hydraulic hybrid drives are thus most interesting under urban and suburban driving conditions. Amongst the existing architectures, the series hydraulic hybrid offers the advantage of operating the internal combustion engine independently of the vehicle speed, at the cost of a less efficient transmission path than a purely mechanical one. Previously, a series hydraulics hybrid light-duty vehicle was modelled in the transmission-line modelling (TLM)-based simulation software Hopsan from the division of Fluid and Mechatronic Systems (Flumes) at Linköping University. This paper studies through simulation-based optimi-zation how the fuel-optimal vehicle design is affected by various mixes of urban and suburban driving requirements. Both the system’s hardware and the parameters of a basic control strategy are considered. The results show quite similar designs for most performance requirements combinations, and can be the base for further studies addressing additional requirements, conditions and objectives.

  • 13.
    Baer, Katharina
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Robustness and performance evaluations for simulation-based control and component parameter optimization for a series hydraulic hybrid vehicle2019In: Engineering optimization (Print), ISSN 0305-215X, E-ISSN 1029-0273, p. 1-19Article in journal (Refereed)
    Abstract [en]

    Simulation-based optimization is a useful tool in the design of complex engineering products. Simulation models are used to capture numerous aspects of the design problem for the objective function. Optimization results obtained can be assessed from various perspectives. In this study, component and control optimization of a series hydraulic hybrid vehicle is used as an application, and different robustness and performance aspects are evaluated. Owing to relatively high computational loads, efficient optimization algorithms are important to provide sufficient quality of results at reasonable computational costs. To estimate problem complexity and evaluate optimization algorithm performance, the definitions for information entropy and the related performance index are extended. The insights gained from various simulation-based optimization experiments and their subsequent analysis help characterize the efficiency of the optimization problem formulation and parameterization, as well as optimization algorithm selection with respect to parallel computation capabilities for further development of the model and optimization framework.

  • 14.
    Bengtsson, Mikael
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    A Control-Oriented 0D Model of a Turbocharger Gas Stand Including Heat Transfer2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A turbocharger’s performance is measured in a gas stand in order to provide information of the components characteristics. The measurement procedure is a very time consuming process and it is thus desired to make it more time-efficient.

    To allow for development of an enhanced control strategy used during the measurements, a 0D model of a gas stand is developed. The physical gas stand components are modeled and validated against measurements, all showing a reasonable result. Turbocharger heat transfers are investigated and modeled using a lumped capacitance approach. The heat transfer models shows approximative results when comparing with measurements which is explained by the lack of temperature measurement made on the bearing housing.

    When the complete gas stand model is validated against measurements, an improvement of the measurement procedure is examined. By adding an idealized heat source with the possibility to heat the compressor housing, it is possible to reduce the time it takes to reach an equilibrium when switching between two steady state operating points. 

  • 15.
    Berg, Tobias
    et al.
    Linköping University, Department of Management and Engineering.
    Carlsson, David
    Linköping University, Department of Management and Engineering.
    Mekanisk säkring av helikopter på fartygsdäck: en konceptuell fallstudie av Saabs UAV-system Skeldar M2008Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    The latest trend within the air force industry is development of unmanned aerial vehicles. The Swedish defense industry group Saab AB is following this trend by means of the introduction of their unmanned helicopter Skeldar V-150. As part of the further development of this system Saab has plans on introducing a marine version of the system, called Skeldar M. One of the purposes of this version is to enable completely autonomous take-offs and landings from ships. To be able to complete this in a safe manner in harsh conditions the helicopter needs to be secured to the deck before take-off as well as after landing.

    The purpose of this thesis has been to develop a concept for keeping Skeldar secured on deck. To establish ideas for these concepts a common method for product development has been used. The method involves acquiring customer needs and from these needs establish a list of demands on the product itself. A set of product concepts are then generated by means of creative thinking and competitor analysis. After that the concepts are compared based on how well they meet the demands put upon them and the best ideas get picked out and further developed.

    The concepts developed in this thesis stretch from simple ideas where hook and loop fasteners are used to secure the helicopter to more advanced ones where the helicopter’s position relative to the ship is measured and the system adjust to this position. All in all nine basic ideas were developed and a total of twelve versions on securing systems. In consultation with people involved in the Skeldar project, three of the concepts were chosen for further development, one concept where the helicopter was winched to the deck, a second where hook and loop fasteners were used to secure it and finally one where vacuum grippers keeps Skeldar on deck.

    With difficulties of implementing a winch system onboard Skeldar as well as on board the ships taken into account, this solution was dropped. This was primarly due to lack of space and difficulties solving an automatic connection between helicopter and ship. The concepts recommended in this thesis will therefore be one of the systems where hook and loop fasteners or vacuum grippers are used.

  • 16.
    Björn, Eriksson
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems . Linköping University, The Institute of Technology.
    Rösth, Marcus
    MCD Parker Hannifin AB.
    Palmberg, Jan-Ove
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems . Linköping University, The Institute of Technology.
    Energy saving system utilizing LQ-technique design2009In: Proceedings of the Seventh International Conference on Fluid Power Transmission and Control: ICPF 2009 / [ed] Yongxiang, Lu and Qingfeng, Wang and Wei, Li and Bingfeng, Ju, Beijing: Beijing World Publishing Corporation , 2009, p. 224-229Conference paper (Refereed)
    Abstract [en]

    This paper deals with the control of individual metering systems. This paper deals with the control of an individual metering system that could be used for reducing metering losses by enabling recuperation and regeneration operation. A system that utilizes individual metering is more flexible than a conventional system since there are more control signals and thereby more outputs to control. Energy saving aspects is among the main reasons for the research on this kind of system, but there is also an opportunity of improvements of the dynamics compared to a conventional system. In this paper an approach with LQtechnique are presented for improvements of system dynamics. Since all states in the system can not be measured a state observer is also considered in the control design. These work present simulations, implementations in a real world forwarder application and results from verifying experiments.

  • 17.
    Blomgren, Martin
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Modeling and control of engaging gears in gearboxes without synchromesh towards specific angles between gear and coupling sleeve2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    When engaging a new gear in an automated manual transmission (AMT) the gear needs to be synchronized with the main shaft's angular velocity in the gearbox. This is so that the parts can be connected through a cog wheel and torque can be transferred. To synchronize the angular velocities, mechanical synchronization components can be used. These components synchronize the velocities during the engagement and can be used with larger differences in angular velocities. Should no mechanical synchronization components be used it puts higher demands on the components rotating at similar velocities to avoid mechanical wear and ensure that the gear can be engaged. In today's systems without mechanical synchronization components the gear is engaged when the angular velocities are within a certain difference. This leads to random angle connections between the cogs and gaps that are to be engaged on the gear and main shaft. This can lead to extended or incomplete engages should the components connect cog to cog.

    This thesis evaluates the possibility to control the angle at which the components connect by using existing sensor signals in the studied system and known parameters. A model of the system is created and simulated to evaluate the probability of predicting the system over the gear engage. Results indicate that it is possible to predict the connection angle close enough to its real value so that a control strategy could be implemented to control the angle to some level.

  • 18.
    Boeira, Felipe
    et al.
    Univ Fed Rio Grande do Sul, Brazil.
    Barcellos, Marinho P.
    Univ Fed Rio Grande do Sul, Brazil.
    de Freitas, Edison P.
    Univ Fed Rio Grande do Sul, Brazil.
    Vinel, Alexey
    Halmstad Univ, Sweden.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    On the Impact of Sybil Attacks in Cooperative Driving Scenarios2017In: 2017 IFIP NETWORKING CONFERENCE (IFIP NETWORKING) AND WORKSHOPS, IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    Platooning employs a set of technologies to manage how a group of vehicles operates, including radar, GPS and Inter-Vehicular Communication (IVC). It uses broadcasted information such as acceleration, position and velocity to operate vehicle members of the platoon. Cooperation among vehicles allows platoons to reduce fuel consumption and risks associated with driver mistakes. In spite of these benefits, the use of IVC to control vehicles exposes a relevant attack surface that can be exploited by malicious actors. In this paper we study the impact of vulnerabilities associated with the Sybil attack (through falsification of multiple identities) and message falsification in vehicular platooning. Simulation results show that this attack may impact the longitudinal control and compromise the entire platoon control.

  • 19.
    Bouilloux-Lafont, Antoine
    et al.
    Linköping University, Department of Management and Engineering, Machine Design.
    Noya Pozo, Rubén
    Development of Acoustic Simulations using Parametric CAD Models in COMSOL2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With constantly changing regulations on emissions, heavy commercial vehicles manufacturershave to adapt for their products to preserve their quality while meetingthese new requirements. Over the past decades, noise emissions have become a greatconcern and new stricter laws demand companies to decrease their vehicle pass-bynoise target values.To address the requirements from different disciplines, Scania follows a simulationdriven design process to develop new concept models EATS. The collaboration amongengineers from different fields is thereby necessary in order to obtain higher performancesilencers. However, the pre-processing step in terms of acoustic simulationsis time-consuming, which can slow the concept development process.In this thesis, a new method was introduced to automate the pre-processing of silenceracoustic models and allow for design optimisation based on acoustic performanceresults. A common Scania product study case was provided to several theseswithin the NXD organisation. The collaboration among the master thesis workersaimed to demonstrate the benefits of KBE and MDO and how they can be integratedwithin Scania’s current concept development and product introduction processes.The performed work was divided in the following steps: data collection, methoddevelopment and concluding work. The first step consisted in gathering sufficientknowledge by conducting a thorough literature review and interviews. Then, an initialmethod was formulated and tested on a simplified silencer model. Once approvedand verified, the method was applied to the study case EATS.The study case showed that a complex product can have its acoustic pre-processingstep automated by ensuring a good connectivity among the required software anda correct denomination of the geometrical objects involved in the simulations. Themethod investigated how morphological optimisations can be performed at bothglobal and local levels to enhance the transmission loss of a silencer. Besides optimisingthe acoustic performance of the models, the method allowed the identificationof correlations and inter-dependencies among their design variables and ouput parameters.

  • 20.
    Brischetto, Mathias
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Improved Functionality for Driveability During Gear-Shift: A Predictive Model for Boost Pressure Drop2015Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Automated gear-shifts are critical procedures for the driveline as they are demanded to work as fast and accurate as possible. The torque control of a driveline is especially important for the driver’s feeling of driveability. In the case of gear-shifts and torque control in general, the boost pressure is key to achieve good response and thereby a fast gear-shift.

    An experimental study is carried out to investigate the phenomena of boost pressure drop during gear-shift and gather data for the modelling work. Results confirm the stated fact on the influence of boost pressure drop on gear-shift completion time and also indicate a clear linear dependence between initial boost pressure and the following pressure drop.

    A dynamic predictive model of the engine is developed with focus on implementation in a heavy duty truck, considering limitations computational complexity and calibration need between truck configurations. The resulting approach is based on a mean value modelling scheme that uses engine control system parameters and functions when possible. To be able to be predictive, a model for demanded torque and engine speed during the gear-shift is developed as reference inputs to the simulation. The simulation is based on a filling and emptying process throughout the engine dynamics, and yields final values of several engine variables such as boost pressure.

    The model is validated and later evaluated in comparison to measurements gathered in test vehicle experiments and in terms of robustness to input and model deviations. Computer simulations yield estimations of the boost pressure drop within acceptable limits. Consid- ering estimations used prior to this thesis the performance is good. Input deviations and modelling inaccuracies are found to inflict significant but not devastating deviations to the model output, possibly more over time with ageing of hardware taken into account.

    Final implementation in a heavy duty truck ecu is carried out with results indicating that the current implementation of the module is relatively computationally heavy. At the time of ending the thesis it is not possible to analyse its performance further, and it is suggested that the module is optimized in terms of computational efficiency. 

  • 21.
    Bråmå, Torsten
    et al.
    Saab, Linköping, Sweden.
    Cronemyr, Peter
    Saab Aerosystems, Linköping, Sweden.
    Hansson, Erik
    Multidisciplinary Optimization of a Composite Wing Using an Alternative Approach for Static Aeroelasticity1995In: Aeroelasticity and structural dynamics 1995, 1995Conference paper (Refereed)
  • 22.
    Casper, Robert
    et al.
    Linköping University, Department of Management and Engineering, Manufacturing Engineering. Linköping University, Faculty of Science & Engineering.
    Sundin, Erik
    Linköping University, Department of Management and Engineering, Manufacturing Engineering. Linköping University, Faculty of Science & Engineering.
    Addressing Today’s challenges in automotive remanufacturing2018In: Journal of Remanufacturing, ISSN 2210-4690Article in journal (Refereed)
    Abstract [en]

    Automotive remanufacturing companies are nowadays facing a wide range ofchallenges. Typical challenges from the point of view of suppliers, producers and customers.Several process steps are analysed and problem fields are dissected: From the core management,to disassembly and cleaning to machining and testing. The main fields of challengesanalysed in this paper are: the vagueness in respect of fiscal value, environmental regulationsand taxation of core parts, the important need for a continuing qualification of staff andengineers, an efficient core management, the adaption of pricing models and the competence tohandle the growing variety and complexity. The focus of this analysis lies on activities of theindependent after-market (IAM) for remanufactured products.

  • 23.
    Casper, Robert
    et al.
    Linköping University, Department of Management and Engineering, Manufacturing Engineering. Linköping University, Faculty of Science & Engineering.
    Sundin, Erik
    Linköping University, Department of Management and Engineering, Manufacturing Engineering. Linköping University, Faculty of Science & Engineering.
    Reverse Logistic Transportation and Packaging Concepts in Automotive Remanufacturing2018In: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 25, p. 154-160Article in journal (Refereed)
    Abstract [en]

    A key process in a closed-loop supply chain is managing and challenging the transportation and packaging management. Strict environmental regulations in connection with transport of environmentally hazardous substances (e.g. oil) are offering a highcost-saving potential in connection with an optimised transportation and packaging concept. The aim of this case orientated paperis to provide the framework for the management of reverse flow of materials in automotive industry. The emphasis is placed onthe remanufacturing activities. To obtain and verify the necessary information for the above mentioned problems, differentmethods and techniques have been applied: 1) Relevant, available literature in connection with this matter was studied; 2) Dataand documents was requested directly by relevant market actors; 3) The clustered data was analysed and samples werehighlighted; and 4) The data was evaluated and recommended courses of action were given. The results show that the mainproblems appear in the area of forward and reverse logistics: Packaging concepts which do not protect the product in an optimalway (forward / reverse logistics). Moreover, packaging concepts which do not protect the environment against potential negativeinfluence of a used part (reverse logistics) A best practice for the transportation of engine components is given and evaluated: Anengine in a metal frame with oil-pan. Securely attached by bolts. Packed in plastic bag.

  • 24.
    Chang, You
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences.
    Kim, Namkeun
    Incheon National University, South Korea.
    Stenfelt, Stefan
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences.
    The development of a whole-head human finite-element model for simulation of the transmission of bone-conducted sound2016In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 140, no 3, p. 1635-1651Article in journal (Refereed)
    Abstract [en]

    A whole head finite element model for simulation of bone conducted (BC) sound transmission was developed. The geometry and structures were identified from cryosectional images of a female human head and eight different components were included in the model: cerebrospinal fluid, brain, three layers of bone, soft tissue, eye, and cartilage. The skull bone was modeled as a sandwich structure with an inner and outer layer of cortical bone and soft spongy bone (diploe) in between. The behavior of the finite element model was validated against experimental data of mechanical point impedance, vibration of the cochlear promontories, and transcranial BC sound transmission. The experimental data were obtained in both cadaver heads and live humans. The simulations showed multiple low-frequency resonances where the first was caused by rotation of the head and the second was close in frequency to average resonances obtained in cadaver heads. At higher frequencies, the simulation results of the impedance were within one standard deviation of the average experimental data. The acceleration response at the cochlear promontory was overall lower for the simulations compared with experiments but the overall tendencies were similar. Even if the current model cannot predict results in a specific individual, it can be used for understanding the characteristic of BC sound transmission in general. (C) 2016 Acoustical Society of America.

  • 25.
    Criscuolo, Ivan
    et al.
    Department of Mechanical Engineering, University of Salerno, Fisciano, Italy.
    Leufvén, Oskar
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Thomasson, Andreas
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Model-Based Boost Pressure Control with System Voltage Disturbance Rejection2011In: Proceedings of the 18th IFAC World Congress, 2011 / [ed] Bittanti, Sergio, Cenedese, Angelo, Zampieri, Sandro, International Federation of Automatic Control (IFAC) , 2011, p. 5058-5063Conference paper (Refereed)
    Abstract [en]

    Actuation systems for automotive boost control incorporate a vacuum tank and PWM controlled vacuum valves to increase the boosting system flexibility. Physical models for the actuator system are constructed using measurement data from a dynamometer with an engine having a two stage turbo system. The actuator model is integrated in a complete Mean Value Engine Model and a boost pressure controller is constructed. The developed model is used as basis for a nonlinear compensator, that is capable of rejecting disturbances from system voltage. An IMC based boost pressure controller is developed for the vacuum actuator and engine by using the engine model and then tested on the test cell. The controller performance is quantified and system voltage disturbance rejection is demonstrated.

  • 26.
    Dell' Amico, Alessandro
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Henriksen, Fredrik
    Skogforsk, the Swedish Forestry Research Institute of Sweden.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Modelling and experimental verification of a secondary controlled six-wheel pendulum arm forwarder2015In: the 13th European Conference of ISTVS / [ed] Roberto Paoluzzi, 2015, p. 1-10Conference paper (Refereed)
    Abstract [en]

    One of the major concerns in the forest industry is the impact on the soil caused by the forest machines duringharvesting, where damages can have a negative impact on e.g. further growth. One of the main reasons is wheel slip.Another concern is the working environment of the operator due to the harsh ground in the forest. Both these issueshave a negative impact on productivity. An attempt to overcome these challenges is made within a collaborative researchproject, which among others also includes Linköping University, where a new six-wheel pendulum arm forwarder isbeing developed. The new forwarder aims at reducing the soil damage by an even pressure distribution and smooth torquecontrol, as well as increased damping of the complete chassis, and thereby improving the working environment. This ispossible since each wheel, driven by its own hydraulic motor, is attached to a pendulum arm allowing to control the heightof each wheel independently of each other. The forwarder has a total maximum weight of 31 tonnes, including 14 tonnesmaximum load. It consists of two steerable joints and is driven by a 360 bhp diesel engine. The transmission consists oftwo hydraulic pumps and six hydraulic motors.This paper deals with the development of the driveline and presents the first experimental tests of the implementedcontrol strategies, where a secondary control approach is chosen for its ability to individually control the torque on eachwheel. The control strategies, presented in the paper, include pressure control, velocity control of the vehicle and ananti-slip controller. To support the development of the control strategies, models of the vehicle and hydraulic subsystemsare derived. The aim with this paper is to verify the concepts on the actual vehicle. The initial results are promising,indicating that the suggested concept is feasible.

  • 27.
    Dell'Amico, Alessandro
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    On Electrohydraulic Pressure Control for Power Steering Applications: Active Steering for Road Vehicles2016Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis deals with the Electrohydraulic Power Steering system for road vehicles, using electronic pressure control valves. With an ever increasing demand for safer vehicles and fewer traffic accidents, steering-related active safety functions are becoming more common in modern vehicles. Future road vehicles will also evolve towards autonomous vehicles, with several safety, environmental and financial benefits. A key component in realising such solutions is active steering.

    The power steering system was initially developed to ease the driver's workload by assisting in turning the wheels. This is traditionally done through a passive open-centre hydraulic system and heavy trucks must still rely on fluid power, due to the heavy work forces. Since the purpose of the original system is to control the assistive pressure, one way would be to use proportional pressure control valves. Since these are electronically controlled, active steering is possible and with closed-centre, energy efficiency can be significantly improved on.

    In this work, such a system is analysed in detail with the purpose of investigating the possible use of the system for Boost curve control and position control for autonomous driving. Commercially available valves are investigated since they provide an attractive solution. A model-based approach is adopted, where simulation of the system is an important tool. Another important tool is hardware-in-the-loop simulation. A test rig of an electrohydraulic power steering system, is developed.

    This work has shown how proportional pressure control valves can be used for Boost curve control and position control and what implications this has on a system level. As it turns out, the valves add a great deal of time lag and with the high gain from the Boost curve, this creates a control challenge. The problem can be handled by tuning the Boost gain, pressure response and damping and has been effectively shown through simulation and experiments. For position control, there is greater freedom to design the controller to fit the system. The pressure response can be made fast enough for this case and the time lag is much less critical.

  • 28.
    Dell'Amico, Alessandro
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Closed-Centre Hydraulic Power Steering by Direct Pressure Control2014In: The 9th JFPS International Symposium on Fluid Power : Matsue 2014 : Oct. 28-31, 2014, The Japan Fluid Power System Society , 2014, p. 332-339Conference paper (Other academic)
    Abstract [en]

    An ongoing trend in the vehicle industry is the development of steering related active safety functions for increased road safety. For this to be a reality there must exist a steering system that allows to either change the road wheel angle or torque by means of an external signal, called active steering. Due to heavy vehicles’ high axle load, hydraulic power is needed to assist the driver in turning the wheels. This paper looks into a solution where self-regulated pressure control valves are used for electronic control of the assistance pressure in order to realise active steering. The valve has closed-centre for a high potential to reduce the energy consumption. A model based approach is used to analyse the system. A non-linear simulation environment is developed to compare the closed-centre system with the original system. A linear analysis is also performed to discover the influence of valve properties on steering system performance. Results have shown that a feasible solution exists and that there exists a relation between valve dynamics, boost gain and steering system loop stability.

  • 29.
    Ekberg, Kristoffer
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Effects of Non Ideal Inlet and Outlet Pipes on Measured Compressor Efficiency2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The thesis is about investigating the inlet and outlet pipes effect on the compressors measured performance. From measurements made in a gas stand, a thermodynamic model is to be created and the compressor efficiency further investigated. The temperatures and pressures entering and leaving the compressor does not have to be the same as the temperatures measured in the gasstand, because of the thermodynamics of the pipes that connects the measurement equipment and the compressor. During a gasstand test the turbocharger is connected in a test bench, it is connected with pipes on both the compressor and turbine side, to simulate the hot exhaust gases from the car engine and the pressure increase over the compressor. The air entering and leaving the turbocharger through the different pipes is controlled and all the entering and leaving temperatures and pressures are measured. Gasstand data from different tests are available during the thesis, one specific turbocharger is used as references during the modeling. Models of the inlet and outlet pipes are created and connected to a compressor model. The model is controlled to give the same mass flow as the measured data, to ensure that the work cycle is followed. The effects of the non ideal inlet and outlet pipes on measured compressor efficiency is studied with help of this model and the main impacts on the measured compressor efficiency are discovered. The result shows that the measured values used to calculate the compressor efficiency could change, depending on the measurement positions on the inlet and outlet pipes. 

  • 30.
    Ekberg, Kristoffer
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Improving Fuel Economy and Acceleration by Electric Turbocharger Control for Heavy Duty Long Haulage2017In: IFAC PAPERSONLINE, ELSEVIER SCIENCE BV , 2017, Vol. 50, no 1, p. 11052-11057Conference paper (Refereed)
    Abstract [en]

    Todays vehicle industry is converging more and more to electrification of vehicles, introducing electrical architectures to cooperate side by side with the combustion engine. This paper investigates the potential of using an electric turbocharger in a long haulage application during highway driving. A charge sustainable control strategy is developed, implemented, tuned, and evaluated on a heavy duty truck model. The benefits of using an electrical turbocharger on a heavy duty diesel truck, from a long haulage perspective, are evaluated. By calibrating the implemented controller, long haulage driving routes can be charge sustainable and consume less fuel than a conventional truck with fix turbine geometry, the fuel savings for the simulated case is 0.9%. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

  • 31.
    Ekberg, Kristoffer
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Sivertsson, Martin
    Linköping University, Department of Electrical Engineering. Linköping University, Faculty of Science & Engineering.
    Cycle Beating - An Analysis of the Boundaries During Vehicle Testing2016In: IFAC PAPERS ONLINE, ELSEVIER SCIENCE BV , 2016, Vol. 49, no 11, p. 657-664Conference paper (Refereed)
    Abstract [en]

    Todays vehicle industry is strictly controlled by environmental legislations. The vehicle industry is spending much money out reducing the fuel consumption and fulfilling the emission requirements to make sales possible in different regions in the world. Before introducing; a vehicle on the market, it is tested according to standardized driving cycles to specify the vehicle pollutant emissions and fuel consumption. These cycles allow some deviation from the reference vehicle speed during tests, e.g. NEDC allows deviations of +/- 2 km/h and +/- 1 s. This paper uses dynamic programming to find fuel optimal velocity profiles, given the allowed deviations of +/- 2 km/h and +/- 1 s from reference speed during drive cycle test. By taking advantage of the allowed deviation, the fuel consumption can be reduced by up to 16.56 % according to model results, ruoriing NEDC if gear selections are unrestricted (i.e. using automatic gearbox), and up to 5.90 % if changing gears according to the specifications in the drive cycle. Two different optimization goals are investigated, minimum amount of mass fuel consumed and best mileage. (C) 2016, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

  • 32.
    Ekman, Petter
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics.
    A Sensitivity Study of Some Numerical and Geometrical Parameters Affecting Lift2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Volvo Car Corporation (VCC) uses Computational Fluid Dynamics (CFD) and wind tunnel during the aerodynamic development of new vehicles. In the past VCC main focus has been on the drag force correlation to the wind tunnel measurements but in recent years improved methods for lift force correlations has been highly wanted. Three objectives were considered in this study to improve the lift force correlation between the CFD simulations and wind tunnel measurements for geometrical configurations of the V60 and S60 models.Poor mesh resolution for the wall bounded flow existed for the VCC mesh method and therefore prisms layers were considered in this thesis to increase the mesh resolution inside the boundary layer.As slick tyres generally were used in the CFD simulations better geometrical correlation was wanted to be studied as it could improve the lift force correlation between CFD simulations and wind tunnel measurements. Therefore detailed tyres were considered in this study.As the coarsest surface mesh size was used for the underbody and the components inside the engine bay, where some of the highest flow velocities occurred, mesh refinements were investigated for engine bay and underbody in this study.The prisms layers improved the predicted behavior for the boundary layer as it captured the large velocity gradients more accurately. Due to this, the skin friction prediction was also improved. Different flow behavior around the front wheels and rear wake occurred due to earlier separation. The different flow field caused an improved correlation for the lift force but worsened correlation for the drag force due to increased pressure at the rear of the cars. However, the front lift force trend correlation for the considered configurations was improved with the prisms layer mesh method.The detailed tyres caused slight more disturbances for the underbody flow which caused more attached flow around the rear of the car hence lowered pressure. Earlier separation around the front wheels also occurred for the detailed tyre geometry as the disturbed flow around the wheels was increased. Slight improved correlation for the front and rear lift forces to the wind tunnel measurements could be seen with the detailed tyre compared to the slick tyre.The mesh refinements for the engine bay and underbody showed significant differences for the flow at the underbody which had significant impact on the flow at the rear wake for the V60 model. Minor differences could be seen for the aerodynamic forces for the baseline configuration for the V60 model while great differences occurred for the configurations affecting the underbody. Due to this significant improved correlation for the front and rear lift force trends were achieved for the underbody configurations with the refined engine bay and underbody mesh method.Conclusions could be drawn that the prisms layer caused earlier separation due to its increased mesh resolution for the wall bounded flow. However, finer mesh resolution was needed inside the boundary layer to ensure consistent separation behavior for both the considered models. Improved correlation for the front lift force could however be seen. The detailed tyre only had minor effects on the flow field and aerodynamic forces and therefore not so important to include for further studies. The refined engine bay and underbody caused significant improved lift force trend correlation to the wind tunnel measurements and should be considered for future studies. To improve the correlation between CFD simulations and wind tunnel measurements increased mesh resolution for the wall bounded flow should be considered to better capture the large velocity gradients close to the wall.

  • 33.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Dell' Amico, Alessandro
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    MODELLING OF A SECONDARY CONTROLLED SIX-WHEEL PENDULUM ARM FORWARDER2015Conference paper (Refereed)
    Abstract [en]

    One of the major concerns in the forest industry is the impact on the soil caused by the forest machines during harvesting, where damage can have a negative impact on growth at replanting for example. Another concern is the working environment of the operator. Both these issues have a negative impact on productivity. A new six-wheel pendulum arm forwarder is being developed within a collaborative research project. The new forwarder aims to reduce soil damage by means of an even pressure distribution and smooth torque control. This paper presents the first step in the development of the driveline, where a secondary control approach is chosen for its ability to control the motion of each wheel individually. Simulation models of both vehicle and driveline have been constructed developed, partly for the development of the control strategy, and partly for evaluation. A speed control concept and a torque control concept have both been evaluated for different scenarios with regard to their ability to reduce wheel slip. Results have shown that a velocity control approach is more sensitive to kinematic model accuracy while wheel slip is handled automatically. A torque control approach is more robust towards model accuracy while the reduction of slip is dependent on an accurate model.

  • 34.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Thomasson, Andreas
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Ekberg, Kristoffer
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Reig, Alberto
    Univ Politecn Valencia, Spain.
    Eifert, Mark
    Ford Res and Innovat Ctr, Germany.
    Donatantonio, Fabrizio
    Univ Salerno, Italy.
    DAmato, Antonio
    Univ Salerno, Italy.
    Arsie, Ivan
    Univ Salerno, Italy.
    Pianese, Cesare
    Univ Salerno, Italy.
    Otta, Pavel
    Czech Tech Univ, Czech Republic.
    Held, Manne
    KTH Royal Inst Technol, Sweden.
    Voegele, Ulrich
    TH Ingolstadt, Germany.
    Endisch, Christian
    TH Ingolstadt, Germany.
    Look-ahead controls of heavy duty trucks on open roads - six benchmark solutions2019In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 83, p. 45-66Article in journal (Refereed)
    Abstract [en]

    A benchmark problem for fuel efficient control of a truck on a given road profile has been formulated and solved. Six different solution strategies utilizing varying degrees of off-line and on-line computations are described and compared. A vehicle model is used to benchmark the solutions on different driving missions. The vehicle model was presented at the IFAC AAC2016 symposium and is compiled from model components validated in previous research projects. The driving scenario is provided as a road slope profile and a desired trip time. The problem to solve is a combination of engine-, driveline- and vehicle-control while fulfilling demands on emissions, driving time, legislative speed, and engine protections. The strength of this publication is the collection of all six different solutions in one paper. This paper is intended to provide a starting point for practicing engineers or researchers who work with optimal and/or model based vehicle control.

    The full text will be freely available from 2020-11-07 15:14
  • 35.
    Evestedt, Niclas
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Sampling Based Motion Planning for Heavy Duty Autonomous Vehicles2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The automotive industry is undergoing a revolution where the more traditional mechanical values are replaced by an ever increasing number of Advanced Driver Assistance Systems (ADAS) where advanced algorithms and software development are taking a bigger role. Increased safety, reduced emissions and the possibility of completely new business models are driving the development and most automotive companies have started projects that aim towards fully autonomous vehicles. For industrial applications that provide a closed environment, such as mining facilities, harbors, agriculture and airports, full implementation of the technology is already available with increased productivity, reliability and reduced wear on equipment as a result. However, it also gives the opportunity to create a safer working environment when human drivers can be removed from dangerous working conditions. Regardless of the application an important part of any mobile autonomous system is the motion planning layer. In this thesis sampling-based motion planning algorithms are used to solve several non-holonomic and kinodynamic planning problems for car-like robotic vehicles in different application areas that all present different challenges.

    First we present an extension to the probabilistic sampling-based Closed-Loop Rapidly exploring Random Tree (CL-RRT) framework that significantly increases the probability of drawing a valid sample for platforms with second order differential constraints. When a tree extension is found infeasible a new acceleration profile that tries to brings the vehicle to a full stop before the collision occurs is calculated. A resimulation of the tree extension with the new acceleration profile is then performed. The framework is tested on a heavy-duty Scania G480 mining truck in a simple constructed scenario.

    Furthermore, we present two different driver assistance systems for the complicated task of reversing with a truck with a dolly-steered trailer. The first is a manual system where the user can easily construct a kinematically feasible path through a graphical user interface. The second is a fully automatic planner, based on the CL-RRT algorithm where only a start and goal position need to be provided. For both approaches, the internal angles of the trailer configuration are stabilized using a Linear Quadratic (LQ) controller and path following is achieved through a pure-pursuit control law. The systems are demonstrated on a small-scale test vehicle with good results.

    Finally, we look at the planning problem for an autonomous vehicle in an urban setting with dense traffic for two different time-critical maneuvers, namely, intersection merging and highway merging. In these situations, a social interplay between drivers is often necessary in order to perform a safe merge. To model this interaction a prediction engine is developed and used to predict the future evolution of the complete traffic scene given our own intended trajectory. Real-time capabilities are demonstrated through a series of simulations with varying traffic densities. It is shown, in simulation, that the proposed method is capable of safe merging in much denser traffic compared to a base-line method where a constant velocity model is used for predictions.

    List of papers
    1. Sampling Recovery for Closed Loop Rapidly Expanding Random Tree using Brake Profile Regeneration
    Open this publication in new window or tab >>Sampling Recovery for Closed Loop Rapidly Expanding Random Tree using Brake Profile Regeneration
    2015 (English)In: Intelligent Vehicles Symposium (IV), 2015 IEEE, IEEE , 2015, p. 101-106Conference paper, Published paper (Refereed)
    Abstract [en]

    In this paper an extension to the sampling based motion planning framework CL-RRT is presented. The framework uses a system model and a stabilizing controller to sample the perceived environment and build a tree of possible trajectories that are evaluated for execution. Complex system models and constraints are easily handled by a forward simulation making the framework widely applicable. To increase operational safety we propose a sampling recovery scheme that performs a deterministic brake profile regeneration using collision information from the forward simulation. This greatly increases the number of safe trajectories and also reduces the number of samples that produce infeasible results. We apply the framework to a Scania G480 mining truck and evaluate the algorithm in a simple yet challenging obstacle course and show that our approach greatly increases the number of feasible paths available for execution.

    Place, publisher, year, edition, pages
    IEEE, 2015
    Series
    IEEE Intelligent Vehicles Symposium, ISSN 1931-0587
    Keywords
    RRT, Autonomous vehicles, motion planning
    National Category
    Control Engineering
    Identifiers
    urn:nbn:se:liu:diva-120929 (URN)10.1109/IVS.2015.7225670 (DOI)000380565800018 ()9781467372664 (ISBN)
    Conference
    2015 IEEE Intelligent Vehicles Symposium (IV), June 28 - July 1, 2015. COEX, Seoul, Korea
    Projects
    iQMatic
    Available from: 2015-08-31 Created: 2015-08-31 Last updated: 2016-11-23Bibliographically approved
    2. Path tracking and stabilization for a reversing general 2-trailer configuration using a cascaded control approach
    Open this publication in new window or tab >>Path tracking and stabilization for a reversing general 2-trailer configuration using a cascaded control approach
    2016 (English)In: Intelligent Vehicles Symposium (IV), 2016 IEEE, Institute of Electrical and Electronics Engineers (IEEE), 2016, p. 1156-1161Conference paper, Published paper (Refereed)
    Abstract [en]

    In this paper a cascaded approach for stabilizationand path tracking of a general 2-trailer vehicle configurationwith an off-axle hitching is presented. A low level LinearQuadratic controller is used for stabilization of the internalangles while a pure pursuit path tracking controller is used ona higher level to handle the path tracking. Piecewise linearityis the only requirement on the control reference which makesthe design of reference paths very general. A Graphical UserInterface is designed to make it easy for a user to design controlreferences for complex manoeuvres given some representationof the surroundings. The approach is demonstrated with challengingpath following scenarios both in simulation and on asmall scale test platform.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2016
    Keywords
    cascade control, control system synthesis, graphical user interfaces, linear quadratic control, mobile robot, path planning, piecewise linear techniques
    National Category
    Control Engineering
    Identifiers
    urn:nbn:se:liu:diva-130950 (URN)10.1109/IVS.2016.7535535 (DOI)000390845600183 ()978-1-5090-1821-5 (ISBN)978-1-5090-1822-2 (ISBN)
    Conference
    2016 IEEE Intelligent Vehicles Symposium, Gothenburg, Sweden, June 19-22, 2016
    Projects
    iQMatic
    Funder
    VINNOVA
    Available from: 2016-09-01 Created: 2016-09-01 Last updated: 2019-01-17Bibliographically approved
  • 36.
    Fors, Victor
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Olofsson, Björn
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Attainable force volumes of optimal autonomous at-the-limit vehicle manoeuvres2019In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, p. 1-22Article in journal (Refereed)
    Abstract [en]

    With new developments in sensor technology, a new generation of vehicle dynamics controllers is developing, where the braking and steering strategies use more information, e.g. knowledge of road borders. The basis for vehicle-safety systems is how the forces from tyre–road interaction is vectored to achieve optimal total force and moment on the vehicle. To study this, the concept of attainable forces previously proposed in literature is adopted, and here a new visualisation technique is devised. It combines the novel concept of attainable force volumes with an interpretation of how the optimal solution develops within this volume. A specific finding is that for lane-keeping it is important to maximise the force in a certain direction, rather than to control the direction of the force vector, even though these two strategies are equivalent for the friction-limited particle model previously used in some literature for lane-keeping control design. More specifically, it is shown that the optimal behaviour develops on the boundary surface of the attainable force volume. Applied to lane-keeping control, this observation indicates a set of control principles similar to those analytically obtained for friction-limited particle models in earlier research, but result in vehicle behaviour close to the globally optimal solution also for more complex models and scenarios.

  • 37.
    Fors, Victor
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Olofsson, Björn
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Formulation and interpretation of optimal braking and steering patterns towards autonomous safety-critical manoeuvres2018In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 57, no 8, p. 1206-1223Article in journal (Refereed)
    Abstract [en]

    Stability control of a vehicle in autonomous safety-critical at-the-limit manoeuvres is analysed from the perspective of lane keeping or lane changing, rather than that of yaw control as in traditional ESC systems. An optimal control formulation is developed, where the optimisation criterion is a linear combination of the initial and final velocity of the manoeuvre. Varying the interpolation parameter in this formulation turns out to result in an interesting family of optimal braking and steering patterns in stabilising manoeuvres. The two different strategies of optimal lane-keeping control and optimal yaw control are shown to be embedded in the formulation and result from the boundary values of the parameter. The results provide new insights and have the potential to be used for future safety systems that adapt the level of braking to the situation at hand, which is demonstrated through examples of how to exploit theresults.

  • 38.
    Hamache, Violette
    Linköping University, Department of Management and Engineering, Mechanics. Linköping University, The Institute of Technology.
    Dynamic Ground Clearance2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this work is to develop a test method which will consider the variation of the ground clearance when driving, the so-called dynamic ground clearance. This has been done through the analysis of a specific application: the tractors in grain used in Brazil.

    Series of real life tests are run in order to obtain data on the tire compressions and the suspension travels. The tractor used is a 6x4 and is loaded with a trailer.

    When investigating critical cases, the minimum dynamic ground clearance is found to be as small as 123 mm at the axle 1, 78 mm at the exhaust outlet, 137 mm at the fuel tank, 35 mm at the bumper and 213 mm at the axle 2.

    These data will be transmitted to the engineer responsible for the chassis design in order for him to get a better understanding of the motion of the truck relative to ground.

  • 39.
    Hansbo, Peter
    et al.
    Department of Mechanical Engineering, Jönköping University, Jönköping, Sweden.
    Rashid, Asim
    Department of Mechanical Engineering, Jönköping University, Jönköping, Sweden.
    Salomonsson, Kent
    Department of Mechanical Engineering, Jönköping University, Jönköping, Sweden.
    Least-squares stabilized augmented Lagrangian multiplier method for elastic contactManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, we propose a stabilized augmented Lagrange multiplier method for the finite element solution of small deformation elastic contact problems. We limit ourselves to friction–free contact with a rigid obstacle, but the formulation is readily extendable to more complex situations.

  • 40.
    Heybroek, Kim
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    On Energy Efficient Mobile Hydraulic Systems: with Focus on Linear Actuation2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this dissertation, energy efficient hydraulic systems are studied. The research focuses on solutions for linear actuators in mobile applications, with emphasis on construction machines. Alongside the aspect of energy efficiency, the thesis deals with competing aspects in hydraulic system design found in the development of construction machines. Simulation models and controls for different concepts are developed, taking the whole machine into account. In line with this work, several proof of concept demonstrators are developed.

    First, pump controlled systems are studied and a novel concept based on an open-circuit pump configuration is conceived. Special consideration is paid to multi-mode capabilities that allow for a broadened operating range and potential downsizing of components. Simulation models and controls are developed and the system is experimentally validated in a wheel loader application.

    Second, the possibility for energy recuperation in valve controlled systems is investigated. In such solutions, a hydraulic motor, added to the meter-out port, is used for energy recovery during load lowering and in multi-function operation. Recuperated energy is either be used momentarily or is stored in a hydraulic accumulator. The proposed solution means an incremental improvement to conventional systems, which is sometimes attractive to machine manufacturers due to fewer uncertainties in reliability, safety and development cost. The energy recovery system is studied on a conceptual level where several alternative systems are proposed and a concept based on a two-machine hydraulic pressure transformer is selected for a deeper control study followed by experimental validation.

    Third, so-called `common pressure rail' systems are suggested. This technique is well established for rotary drives, at least for the industrial sector. However, in applying this technique to mobile hydraulics, feasible solutions for linear actuators are needed. In this dissertation, two approaches to this problem are presented. The first one is the hydraulic pressure transformer, studied in simulation as the key-component of a `series hybrid' topology for wheel loaders. In the second approach variable displacement linear actuators (VDLA) based on a 4-chamber cylinder and multi-mode control is applied. In a theoretical study a model predictive control approach is suggested and new insights to the trade-off between controllability and energy efficiency of a multi-chamber cylinder are presented. Finally, a fullscale hydraulic hybrid system based on secondary controlled hydraulic motors and VDLAs is designed and experimentally validated on a large excavator.

    List of papers
    1. Applied Control Strategies for a Pump Controlled Open Circuit Solution
    Open this publication in new window or tab >>Applied Control Strategies for a Pump Controlled Open Circuit Solution
    2008 (English)In: Proceedings of the 6:th IFK: International Fluid Power Conference, Dresden, Germany, Dresden: Dresdner Verein zur Förderung der Fluidtechnik e.V. , 2008, p. 39-52Conference paper, Published paper (Other academic)
    Abstract [en]

    Today’s mobile machines most often contain hydraulic valve controlled drives in an open loop-circuit. For the purpose of saving energy the constant pressure pumps have, in the past, often been replaced by load-sensing pumps and load-sensing valves. In mobile applications these load-sensing solutions have significantly reduced the energy consumption. However, in applications with unequal drive pressure levels the load sensing systems still result in energy losses, referred to as metering losses. Throttling losses associated to load lowering have also been paid more attention to in the energy debates. By instead adopting direct pump displacement control, with the capability of energy recuperation in lowering motions, many of these losses can be avoided. In this article the author has studied a hydraulic system configuration where each actuator/supply system comprises a variable displacement pump/motor working in an open-circuit together with four separate electrically controlled valves. The four valves render a solution versatile in control, as the cylinder chambers can be connected to pump and/or tank as well as be closed at any time. The pump is electrically controlled and is used either in pressure control mode or flow control mode depending on the state of operation. Along with the hardware described above, the open-circuit solution requires a number of electronic sensors as well as a microprocessor control system, hence the system is a mechatronic system. In contrast to a conventional hydraulic system the control objectives in this concept are not strictly defined by the hardware configuration, but instead many of its critical parameters can be adjusted in software, thus an increased flexibility in system design is obtained. Consequently, defining the desired system properties becomes even more important. Furthermore system robustness must be considered to a greater extent, due to the increased number of sensors and components. The main focus in this paper is to show how machine operability and performance depends on a set of chosen control strategies, what can be achieved as to energy efficiency and driver comfort and at what cost. Additionally the trade-off between energy efficiency and comfort is discussed. In previous work the author has investigated the influence on energy efficiency by lowering loads in different modes of operation, in respect to how the valves are controlled. In this article strategies to decide which mode of operation is the most energy efficient are considered, and how transitions between these modes can be handled by pressure matching prior to opening valves. As the open circuit solution does not support energy storage over time, methods to manage recuperated excess energy is investigated in order to prevent the primary mover from speeding up. The author will also discuss some application specific challenges where a wheel loader has been equipped with the open-circuit solution. For instance, how to handle interference between drives due to the mechanical coupling in the lifting framework and how to handle load actuation over gravity center.

    Place, publisher, year, edition, pages
    Dresden: Dresdner Verein zur Förderung der Fluidtechnik e.V., 2008
    Keywords
    Pump control, control strategies, energy recuperation, mode switching
    National Category
    Fluid Mechanics and Acoustics
    Identifiers
    urn:nbn:se:liu:diva-16073 (URN)
    Available from: 2009-01-07 Created: 2009-01-07 Last updated: 2017-10-26Bibliographically approved
    2. Modelling and Control of a Complementary Energy Recuperation System for Mobile Working Machines
    Open this publication in new window or tab >>Modelling and Control of a Complementary Energy Recuperation System for Mobile Working Machines
    2013 (English)In: / [ed] Petter Krus, Magnus Sethson, Liselott Ericson, Linköping: Linköping University Electronic Press, 2013, p. 21-30Conference paper, Published paper (Refereed)
    Abstract [en]

    The concept of hybrid technologies for mobile working machines has gained increased attention in recent years. This paper deals with a parallel hybrid system for energy recuperation based on a two-machine hydraulic transformer. The system can be connected hydraulically to an existing hydraulic circuit as a complementary add-on system. The linear analysis of the system visualises the control difficulties coming from a low inertia, slow control dynamics of the machines and the non-linear stick-slip friction during low speeds. A control strategy based on linear control methods is proposed and evaluated in a hardware test bench. It is shown that an acceptable performance can be achieved even with fairly simple models. Additionally, a start-up procedure is proposed to start the transformer from zero speed

    Place, publisher, year, edition, pages
    Linköping: Linköping University Electronic Press, 2013
    Series
    Linköping Electronic Conference Proceedings, ISSN 1650-3686, E-ISSN 1650-3740 ; 092
    Keywords
    Parallel hybrid, Energy recuperation, Hydraulic transformer
    National Category
    Applied Mechanics
    Identifiers
    urn:nbn:se:liu:diva-100142 (URN)10.3384/ecp1392a3 (DOI)978-91-7519-572-8 (ISBN)
    Conference
    13th Scandinavian International Conference on Fluid Power, June 3-5, 2013, Linköping, Sweden
    Available from: 2013-10-29 Created: 2013-10-29 Last updated: 2018-02-02Bibliographically approved
    3. Towards Resistance-free Hydraulics in Construction Machinery
    Open this publication in new window or tab >>Towards Resistance-free Hydraulics in Construction Machinery
    2012 (English)In: 8th International Fluid Power Conference, Dresden: Dresdner Verein zur Förderung der Fluidtechnik , 2012, Vol. 2, p. 123-138Conference paper, Published paper (Refereed)
    Abstract [en]

    The topic of resistance-free motion control refers to solutions that minimize or completely eliminate the need for proportional valves, hence avoiding the throttling losses associated with metering. Previous research by the authors shows how a secondary control system could be used to improve energy efficiency in construction machines. The proposed solution uses hydraulic transformers, powered by a common pressure rail system driving both the linear work implements and the rotary drives of a propulsion system in a wheel loader. An emphasis in this paper is on the sizing aspects of transformer-based system design. The solution under special observation enables the use of smaller transformers utilizing the differential cylinder as a two-stage gearbox by means of “short-circuiting” its two cylinder chambers. The results and outlook from this study touch on how state-of-the-art secondary control systems could improve the energy efficiency of future construction machinery and suggest potential areas of improvement.

    Place, publisher, year, edition, pages
    Dresden: Dresdner Verein zur Förderung der Fluidtechnik, 2012
    National Category
    Other Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-132927 (URN)
    Conference
    8th International Fluid Power Conference, Dresden, March 26-28, 2012
    Funder
    Swedish Energy Agency, P32064-1
    Available from: 2016-12-01 Created: 2016-12-01 Last updated: 2017-10-26Bibliographically approved
    4. A novel hydromechanical hybrid motion system for construction machines
    Open this publication in new window or tab >>A novel hydromechanical hybrid motion system for construction machines
    2017 (English)In: International Journal of Fluid Power, ISSN 1439-9776, Vol. 18, no 1, p. 17-28Article in journal (Refereed) Published
    Abstract [en]

    This paper deals with a novel type of hybrid motion system for construction machines based on a common pressure rail shared between a hydromechanical power-split transmission and secondary controlled work hydraulics. A construction machine with driveline and work functions is a complex coupled motion system and the design of an effective hybrid system needs to take both subsystems into account. Studies on energy efficient hybrid systems for construction machines have hitherto principally focused on one subsystem at a time - work hydraulics or driveline. The paper demonstrates a use case with a specific transmission concept proposal for a medium-sized wheel loader. The system is modelled and simulated using an optimal energy management strategy based on dynamic programming. The results show the benefits of a throttle-free bidirectional link between the machine's subsystems and the energy storage, while taking advantage of the complex power flows of the power-split transmission.

    Place, publisher, year, edition, pages
    Abingdon, UK: Taylor & Francis, 2017
    National Category
    Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-142329 (URN)10.1080/14399776.2016.1210423 (DOI)
    Available from: 2017-10-26 Created: 2017-10-26 Last updated: 2017-11-09Bibliographically approved
  • 41.
    Hjälmdahl, Magnus
    et al.
    Sweco.
    Ahlström, Christer
    The Swedish National Road and Transport Research Institute.
    Henriksson, Per
    The Swedish National Road and Transport Research Institute.
    Sundström, Christofer
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Driving style and energy consumption with everyday use of a plug-in hybrid electric vehicle2018Conference paper (Refereed)
    Abstract [en]

    Chargeable vehicles with focus on plug-in hybrid vehicles have become common. The impact PHEVs have on the energy consumption significantly varies with driving behaviour, charging possibilities, and the driving mission. This study investigates how PHEVs function during real driving. Questionnaires, interviews, and measurement vehicle data are evaluated. Key findings is that the fuel consumption decreases significantly at low speeds compared to a combustion engine vehicle, and that the drivers believe that they adopt the driving to the characteristics of the PHEV, but this is not found in the measurement data. The vehicle is behavious in the way the driver wants without any adaptation required.

  • 42.
    Holmbom, Robin
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Liang, Bohan
    Volvo Car Corporation.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Investigation of Performance Differences and Control Synthesis for Servo-Controlled and Vacuum-Actuated Wastegates2017In: SAE Technical Paper 2017-01-0592, SAE International , 2017, article id 2017-01-0592Conference paper (Refereed)
    Abstract [en]

    Turbocharging plays an important role in the downsizing of engines. Model-based approaches for boost control are going to increasing the necessity for controlling the wastegate flow more accurately. In today’s cars, the wastegate is usually only controlled with a duty cycle and without position feedback. Due to nonlinearities and varying disturbances a duty cycle does not correspond to a certain position. Currently the most frequently used feedback controller strategy is to use the boost pressure as the controller reference. This means that there is a large time constant from actuation command to effect in boost pressure, which can impair dynamic performance. In this paper, the performance of an electrically controlled vacuum-actuated waste-gate, subsequently referred to as vacuum wastegate, is compared to an electrical servo-controlled wastegate, also referred to as electric wastegate. Their performance is investigated with the two actuators installed on a turbocharged inline four gasoline engine in an engine test bench. Furthermore, different control synthesis designs for these different actuators are investigated. A state-feedback controller with standard models for the electric wastegate is described and implemented, which gives a position-controlled wastegate. One main difference between vacuum and electric wastegate is that the latter has a position sensor. To make an extended comparison between the solutions, the vacuum wastegate is also equipped with a position sensor and controller using standard controller design methods. The controllers are implemented and compared both in a simulation environment and evaluated in an engine test bench. In addition, for the electric wastegate, both soft-landing and tightening features are also implemented and investigated. Their aim is to improve the lifetime and behavior at or near the closed position.

  • 43.
    Hultqvist, Daniel
    et al.
    Autoliv Electronics AB, Linköping, Sweden.
    Roll, Jacob
    Autoliv Electronics AB, Linköping, Sweden.
    Svensson, Fredrik
    Autoliv Electronics AB, Linköping, Sweden.
    Dahlin, Johan
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Schön, Thomas
    Department of Information Technology, Uppsala University.
    Detecting and positioning overtaking vehicles using 1D optical flow2014In: Proceedings of the 2014 IEEE Intelligent Vehicles Symposium, 2014, p. 861-866Conference paper (Refereed)
    Abstract [en]

    We are concerned with the problem of detecting an overtaking vehicle using a single camera mounted behind the ego-vehicle windscreen. The proposed solution makes use of 1D optical flow evaluated along lines parallel to the motion of the overtaking vehicles. The 1D optical flow is computed by tracking features along these lines. Based on these features, the position of the overtaking vehicle can also be estimated. The proposed solution has been implemented and tested in real time with promising results. The video data was recorded during test drives in normal traffic conditions in Sweden and Germany.

  • 44.
    Jakobsson, Thommy
    Linköping University, Department of Electrical Engineering.
    Model Based Evaluation of UEGO Performance and Sensitivity2006Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    Closed loop fuel injection have been in use for two decades but it's not until the recent five years that the wide band lambda sensor have been utilized. The goal is to explain wide band and discrete lambda sensors in a simple but powerful way. Both sensors are modeled by simple mathematics and accounts for Oxygen, Hydrogen and Carbon monoxide influences. The focus is not just on the output from the sensors, but also on the underlying function. This means that all explanations are thorough and methodical. The function of a wide band lambda sensor is more complicated than a discrete type lambda sensor, therefore it's harder to get correct readings. The model of the wide band lambda sensor is used to evaluate different problems in preparation for the development of an observer. Several potential problem sources are tested and investigated, these include calibration error, pressure error, air leak error, gas sensitivity and fuel errors. To evaluate the potential problems and their ability to explain differences between actual lambda and sensor output, two sensors with differing outputs have been used. The final result is implemented in an ECU.

    The models indicate that the difference between the two sensors is most likely explained by different sensitivity for CO, O2 and H2. This can in turn have one or several explanations. It is suggested that different ability to pump oxygen, different nernst cells or even different controllers can cause this. The reason is not investigated further as this would require a very deep research on the two sensors. Because no usable explanation is found an observer that estimates the offset at stoichiometric conditions, where lambda equals one, is constructed. The observer uses the fact that the switch point of a discrete lambda sensor is insensitive to disturbances. The offset calculation is performed in real time on an ECU. Tools for calibration of the observer are also developed. With the observer the error for the two sensors is roughly halved over the whole spectrum and at stoichiometric conditions, which is the normal operation for an engine, the error was too small to measure.

    Although the wide band lambda sensor is a very complex sensor it is shown that it can be understood with simple mathematics and basic knowledge in chemistry. The developed model agrees well with the real sensor for steady state conditions. For transient conditions, however, the model needs to be refined further. The question why the two sensors differ is discussed but the true origin of the cause remains unsolved. The conclusion is that the error can be drastically reduced with just an offset. It is also shown that when building a lambda sensing device the controller is of equal importance as the sensor element itself. This is due to the sensitivity of surrounding factors that the controller must be able to handle. These effects are specially important for engines running at lambda not equal to 1, for example diesel engines.

  • 45.
    Jansson, Andreas
    et al.
    Statens väg- och transportforskningsinstitut, Fordonsteknik och simulering, FTS.
    Olsson, Erik
    Statens väg- och transportforskningsinstitut, Fordonsteknik och simulering, FTS.
    Linder, Jonas
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Hjort, Mattias
    Statens väg- och transportforskningsinstitut, Fordonsteknik och simulering, FTS.
    Developing of a Driver Model for Vehicle Testing2014In: Proceedings of the 14th International Symposium on Advanced Vehicle Control (AVEC), Tokyo, September 2014, 2014Conference paper (Refereed)
    Abstract [en]

    There is today no established automated method for testing vehicles or tyres, and the most common option is using professional drivers for this purpose. The tests are supposed to be fair and repeatable, which means using human drivers for these kinds of vehicle testing is not an option. Using a steering robot modelled to drive as a human is therefore preferable. The approach described in this paper shows how a driver model can be created by using a control algorithm based on gathered data from human drivers performing double lane change (DLC) manoeuvres in a simulator. The implemented controller shows how human drivers’ behaviors can be captured using control theory.

  • 46.
    Joborn, Martin
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems.
    Leander, Per
    Transrail Sweden AB.
    Lidén, Tomas
    Transrail Sweden AB.
    Nordmark, Thomas
    LKAB.
    Energy efficiency and on-time performance for heavy haul trains2011In: International Heavy Haul Association Conference, Conference Proceedings, 2011Conference paper (Refereed)
    Abstract [en]

    The driving advisory system CATO has been installed at iron ore trains at LKAB, Sweden. CATO uses radio communication to communicate, e.g., the operational timetable and train status between the train control center and the trains. The advisories both enable the drivers to keep the operational timetable with very high precision and reduce the energy consumption by 20-25 percent. CATO’s speed advisories are easy to follow, and can easily be adapted to be relevant for heavy haul driving under extreme conditions.

  • 47.
    Johansson, Hampus
    et al.
    Linköping University. Linköping University, Department of Management and Engineering. Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems .
    Höglund, Nicklas
    Linköping University. Linköping University, Department of Management and Engineering. Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems .
    Weight Estimation through Frequency Analysis2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The weight of a heavy duty vehicle plays an important role when dealing with different control systems. Examples of control units in a truck that need this parameter are the ones used to control the brakes, the engine and the gearbox. An accurate estimation of the weight leads not only to a more fuel efficient and safer transport, but also assures the driver that current law limits are not exceeded. The weight can be estimated with pretty good accuracy if the truck is equipped with air suspension. In trucks that lack this type of suspension other methods are used to estimate the weight. At present these methods are inaccurate. In this thesis a new method where the weight is to be estimated through frequency analysis of the truck's driveline is developed and evaluated.

  • 48.
    Johansson, Linus
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Full Cycle Cylinder State Estimation in DI Engines with VVA2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Tougher legal demands on pollutions require a better developed understanding of the processes that take place in the cylinder. The thesis contributes with a cylinder model that uses the same set of equations for intake, compression,expansion/combustion and exhaust. The cylinder model describes the states temperature, pressure and the mass fraction of air.The model is able to simulate the gas exchange with compressible flows over the valves, it handles VVT, CRB and blowby. The combustion is modeled with asingle Vibe function that describes the heat release and the consumption of air.The model is general enough to be able to simulate both SI and CI engines. The calibrations that are needed are the discharge coefficient CD values for intake and exhaust valves, blowby, and heat release/transfer parameters. Furthermore, the engine geometry parameters have to be provided to be able to calculate the instanteneous cylinder volume. The model has shown good agreement for cylinder pressure curves with and without combustion and can handle phasingof the valve lifts. That shows that the model can handle the important casesin combustion engines. It is easy to replace sub models in the cylinder model e.g. single Vibe with double Vibe. In the model, in the cylinder is calculated and the average instantenous torque for the entire engine is calculated from thestates in one cylinder. These two calculations have shown good agreement withthe stationary measurments done in an engine test cell. The model is able to use fixed step lengths for even processor loads, the size of the step lengths are resonable for real time implementation on an ECU.

  • 49.
    Johansson, Max
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Optimal Control of Heat Transfer Rates in Turbochargers2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 50.
    Karlgren Johansson, Mikael
    et al.
    Linköping University, Department of Management and Engineering, Machine Design.
    Leong, Kevin
    Linköping University, Department of Management and Engineering, Machine Design.
    Auxiliary Heater for Natural Gas Trucks2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As alternative fuels are becoming more common, technologies need to adjust to them. Natural gas is one of the alternative fuels that has grown during the latest years in the transport sector. Natural gas consists of around 97 % methane and is the cleanest fossil fuel. The use of natural gas can make it easier to transition to biogas as it has equivalent properties.

    Today Scania CV AB's trucks fuelled by natural gas are using auxiliary cabin heaters driven by diesel. This means that the natural gas trucks have two fuels on-board the truck. The goal of this project is to find a concept to eliminate the diesel fuel and replace it with an auxiliary cabin heater driven by another energy source. It will improve the heating solution and make it superior from an environmental perspective.

    The result of the project lead to a short-term solution with an auxiliary heater fuelled by natural gas. A long-term solution is to have a cooperation with a manufacturer to develop a better natural gas auxiliary heater that fulfils more of the requirements in the technical specification. An experiment plan is devised to test parameters out of reach of the project. 

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