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Vehicle Powertrain Test Bench Co-Simulation with a Moving Base Simulator Using a Pedal Robot
Vehicle Technology and Simulation, VTI, Linköping, Sweden.
Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
Vehicle Technology and Simulation, VTI, Linköping, Sweden.
Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
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.

Place, publisher, year, edition, pages
2013. Vol. 6, no 1, p. 169-179
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-92215DOI: 10.4271/2013-01-0410OAI: oai:DiVA.org:liu-92215DiVA, id: diva2:620344
Available from: 2013-05-08 Created: 2013-05-08 Last updated: 2019-04-28Bibliographically approved
In thesis
1. Evaluation, Transformation, and Extraction of Driving Cycles and Vehicle Operations
Open this publication in new window or tab >>Evaluation, Transformation, and Extraction of Driving Cycles and Vehicle Operations
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

A driving cycle is a representation of how vehicles are driven and  is usually represented by a set of data points of vehicle speed  versus time.  Driving cycles have been used to evaluate vehicles for  a long time. A traditional usage of driving cycles have been in  certification test procedures where the exhaust gas emissions from  the vehicles need to comply with legislation. Driving cycles are now  also used in product development for example to size components or  to evaluate different technologies.  Driving cycles can be just a  repetition of measured data, be synthetically designed from  engineering standpoints, be a statistically equivalent  transformation of either of the two previous, or be obtained as an  inverse problem e.g. obtaining driving/operation patterns.  New  methods that generate driving cycles and extract typical behavior  from large amounts of operational data have recently been proposed.  Other methods can be used for comparison of driving cycles, or to  get realistic operations from measured data. 

This work addresses evaluation, transformation and extraction of  driving cycles and vehicle operations.  To be able to test a vehicle  in a controlled environment, a chassis dynamometer is an  option. When the vehicle is mounted, the chassis dynamometer  simulates the road forces that the vehicle would experience if it  would be driven on a real road. A moving base simulator is a  well-established technique to evaluate driver perception of e.g. the  powertrain in a vehicle, and by connecting these two simulators the  fidelity can be enhanced in the moving base simulator and at the  same time the mounted vehicle in the chassis dynamometer is  experiencing more realistic loads. This is due to the driver's  perception in the moving base simulator is close to reality. 

If only a driving cycle is considered in the optimization of a  controller there is a risk that the controllers of vehicles are  tailored to perform well in that specific driving cycle and not  during real-world driving. To avoid the sub-optimization issues, the  operating regions of the engine need to be excited differently. This  can be attained by using a novel algorithm, which is proposed in  this thesis, that alters the driving cycle while maintaining that  the driving cycle tests vehicles in a similar way. This is achieved  by keeping the mean tractive force constant during the process. 

From a manufacturers standpoint it is vital to understand how your  vehicles are being used by the customers. Knowledge about the usage  can be used for design of driving cycles, component sizing and  configuration, during the product development process, and in  control algorithms.  To get a clearer picture of the usage of wheel  loaders, a novel algorithm that automatically, using existing  sensors only, extracts information of the customers usage, is  suggested. The approach is found to be robust when evaluated on  measured data from wheel loaders loading gravel and shot rock.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2013. p. 103
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1596
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-92180 (URN)LIU-TEK-LIC-2013:30 (Local ID)978-91-7519-597-1 (ISBN)LIU-TEK-LIC-2013:30 (Archive number)LIU-TEK-LIC-2013:30 (OAI)
Presentation
2013-05-30, Visionen, Hus B, Campus Valla, Linköpings universitet, Linköping, 10:15 (Swedish)
Opponent
Supervisors
Available from: 2013-05-08 Created: 2013-05-08 Last updated: 2019-12-08Bibliographically approved
2. Evaluation, Generation, and Transformation of Driving Cycles
Open this publication in new window or tab >>Evaluation, Generation, and Transformation of Driving Cycles
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Driving cycles are important components for evaluation and design of vehicles. They determine the focus of vehicle manufacturers, and indirectly they affect the environmental impact of vehicles since the vehicle control system is usually tuned to one or several driving cycles. Thus, the driving cycle affects the design of the vehicle since cost, fuel consumption, and emissions all depend on the driving cycle used for design. Since the existing standard driving cycles cannot keep up with the changing road infrastructure, the changing vehicle fleet composition, and the growing number of vehicles on the road, which do all cause changes in the driver behavior, the need to get new and representative driving cycles are increasing. A research question is how to generate these new driving cycles so that they are both representative and at the same time have certain equivalence properties, to make fair comparisons of the performance results. Besides generation, another possibility to get more driving cycles is to transform the existing ones into new, different, driving cycles considering equivalence constraints.

With the development of new powertrain concepts the need for evaluation will increase, and an interesting question is how to utilize new developments in dynamometer technology together with new possibilities for connecting equipment. Here a pedal robot is developed to be used in a vehicle mounted in a chassis dynamometer and the setup is used for co-simulation together with a moving base simulator that is connected with a communication line. The results show that the co-simulation can become a realistic driving experience and a viable option for dangerous tests and a complement to tests on a dedicated track or on-road tests, if improvements on the braking and the vehicle feedback to the driver are implemented.

The problem of generating representative driving cycles, with specified excitation at the wheels, is approached with a combined two-step method. AMarkov chain approach is used to generate candidate driving cycles that are then transformed to equivalent driving cycles with respect to the mean tractive force components, which are the used measures. Using an optimization methodology the transformation of driving cycles is formulated as a nonlinear program with constraints and a cost function to minimize. The nonlinear program formulation can handle a wide range of constraints, e.g., the mean tractive force components, different power measures, or available energy for recuperation, and using the vehicle jerk as cost function gives good drivability.

In conclusion, methods for driving cycle design have been proposed where new driving cycles can either be generated from databases, or given driving cycles can be transformed to fulfill certain equivalence constraints, approaching the important problem of similar but not the same. The combination of these approaches yields a stochastic and general method to generate driving cycles with equivalence properties that can be used at several instances during the product development process of vehicles. Thus, a powerful and effective engineering tool has been developed.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2015. p. 17
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1669
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Computer Engineering
Identifiers
urn:nbn:se:liu:diva-117549 (URN)10.3384/diss.diva-117549 (DOI)978-91-7519-065-5 (ISBN)
Public defence
2015-06-10, Visionen, Hus B, Campus Valla, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2015-05-21 Created: 2015-05-04 Last updated: 2019-11-15Bibliographically approved
3. Extensions for Distributed Moving Base Driving Simulators
Open this publication in new window or tab >>Extensions for Distributed Moving Base Driving Simulators
2017 (English)Licentiate 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.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2017. p. 18
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1777
National Category
Vehicle Engineering Computer Systems
Identifiers
urn:nbn:se:liu:diva-136146 (URN)10.3384/lic.diva-136146 (DOI)9789176855249 (ISBN)
Presentation
2017-05-12, Alan Turing, hus E, Campus Valla, Linköping University, Linköping, 10:15 (English)
Opponent
Supervisors
Funder
Vinnova, 2011-03994
Available from: 2017-03-30 Created: 2017-03-30 Last updated: 2019-10-28Bibliographically approved
4. Distributed Moving Base Driving Simulators: Technology, Performance, and Requirements
Open this publication in new window or tab >>Distributed Moving Base Driving Simulators: Technology, Performance, and Requirements
2019 (English)Doctoral 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.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2019. p. 42
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1984
National Category
Computer Systems Vehicle Engineering
Identifiers
urn:nbn:se:liu:diva-156537 (URN)10.3384/diss.diva-156537 (DOI)9789176850909 (ISBN)
Public defence
2019-06-04, Ada Lovelace, hus B, Campus Valla, Linköping, 13:15 (English)
Opponent
Supervisors
Available from: 2019-04-30 Created: 2019-04-28 Last updated: 2019-08-22Bibliographically approved

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