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  • 201.
    Hellström, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Åslund, Jan
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik.
    Design of a Well-behaved Algorithm for On-board Look-ahead Control2008Inngår i: IFAC World Congress,2008, 2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A look-ahead controller is developed for a heavy diesel truck that utilizes information about the road topography ahead of the vehicle when the route is known. A dedicated prediction model is formulated where special attention is given to properly include gear shifting. The nature of the problem is analyzed for the purpose of optimization, and a well performing dynamic programming algorithm is tailored. A key step for satisfactory solutions with a sufficiently low computational effort is to avoid numerical problems. The focus here is the choice of discretization method, and it turns out that a basic analysis give decisive insight into the interplay between the criterion and the discretization errors. The resulting algorithm is demonstrated to perform well in real on-line tests on a highway.

  • 202.
    Hellström, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Åslund, Jan
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Design of an efficient algorithm for fuel-optimal look-ahead control2010Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 18, nr 11, s. 1318-1327Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A fuel-optimal control algorithm is developed for a heavy diesel truck that utilizes information about the road topography ahead of the vehicle when the route is known. A prediction model is formulated where special attention is given to properly include gear shifting. The aim is an algorithm with sufficiently low computational complexity. To this end, a dynamic programming algorithm is tailored, and complexity and numerical errors are analyzed. It is shown that it is beneficial to formulate the problem in terms of kinetic energy in order to avoid oscillating solutions and to reduce linear interpolation errors. A residual cost is derived from engine and driveline characteristics. The result is an on-board controller for an optimal velocity profile and gear selection.

  • 203.
    Hellström, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Åslund, Jan
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Horizon length and fuel equivalents for fuel-optimal look-ahead control2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Recent studies from several authors show that it is possible to lower the fuel consumption for heavy trucks by utilizing information about the road topography ahead of the vehicle. The approach in these studies is receding horizon control where horizon length and residual cost are main topics. To approach these topics, fuel equivalents previously introduced based on physical intuition are given a mathematical interpretation in terms of Lagrange multipliers. Measures for the suboptimality, caused by the truncated horizon and the residual cost approximation, are defined and evaluated for different routes and parameters.

  • 204.
    Hellström, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Åslund, Jan
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Management of kinetic and electric energy in heavy trucks2010Inngår i: Transmission and Driveline, 2010, SAE International , 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Hybridization and velocity management are two important techniques for energy efficiency that mainly have been treated separately. Here they are put in a common framework that from the hybridization perspective can be seen as an extension of the equivalence factor idea in the well known strategy ECMS. From the perspective of look-ahead control, the extension is that energy can be stored not only in kinetic energy, but also electrically. The key idea is to introduce more equivalence factors in a way that enables efficient computations, but also so that the equivalence factors have a physical interpretation. The latter fact makes it easy to formulate a good residual cost to be used at the end of the look-ahead horizon. The formulation has different possible uses, but it is here applied on an evaluation of the size of the electrical system. Previous such studies, for e.g. ECMS, have typically used a driving cycle, i.e. a fixed velocity profile, but here the extra freedom to choose an optimal driving pattern is added.

  • 205.
    Henriksson, Tomas
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Modeling effects due to varying command signal timing1998Inngår i: IFAC Proceedings Volumes, 1998, Vol. 31, s. 175-179Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Engine models has a basic role in fuel control, and Shafai et al have recently reported excellent results using a first order system with a time delay. The fractional time delay plays a crucial in their work. Given their success, it is interesting to look at some principle issues depending on different engine models and different ways of actuator timing. Experiments on other engines may e.g. give models of second order. In addition there is random component of the time delay, which vary due to the coordination between event based processes and time based processes. A result is that even with no process noise and no measurement noise, the variation in fractional time delay can cause errors in the parameter identification. It is shown that the resulting errors can not be modeled as a moving average of white noise. Further, there is always a zero that drifts towards the unit circle along the negative real axis, and there may also be other zeros and poles drifting if the choice of method with associated parameters are not made properly. In conclusion, such observations are important when designing fuel control for engines.

  • 206.
    Hilding, Emil
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Enthalpy Based Boost Pressure Control2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    A turbo system is driven by the excess energy in the exhaust gases.  As a result, variation in exhaust temperature cause variations in  boost pressure. By using the information about the available exhaust  energy in the turbo controller directly through a feedforward  controller, an unexpected variation in turbo boost can be avoided. A  model based controller is developed that calculates the desired  turbine power from the boost pressure reference and then, by  observing the available exhaust energy, controls the generated  turbine power to match the desired power. A Mean Value Engine Model  has been used to make simulation with the developed controller  implemented. Steps between different boost pressure references are  used to evaluate controller performance. Tests in a car have also  been made to make sure the simulation results are consistent in a  real environment.

  • 207.
    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
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Driving style and energy consumption with everyday use of a plug-in hybrid electric vehicle2018Konferansepaper (Fagfellevurdert)
    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.

  • 208.
    Hockerdal, Erik
    et al.
    Scania CV AB, Sweden.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Real-time performance of DAE and ODE based estimators evaluated on a diesel engine2018Inngår i: Science China Information Sciences, ISSN 1674-733X, E-ISSN 1869-1919, Vol. 61, nr 7, artikkel-id 70202Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Computation and sampling time requirements for real-time implementation of observers is studied. A common procedure for state estimation and observer design is to have a system model in continuous time that is converted to sampled time with Euler forward method and then the observer is designed and implemented in sampled time in the real time system. When considering state estimation in real time control systems for production there are often limited computational resources. This becomes especially apparent when designing observers for stiff systems since the discretized implementation requires small step lengths to ensure stability. One way to reduce the computational burden, is to reduce the model stiffness by approximating the fast dynamics with instantaneous relations, transforming an ordinary differential equations (ODE) model into a differential algebraic equation (DAE) model. Performance and sampling frequency limitations for extended Kalman filter (EKF)s based on both the original ODE model and the reduced DAE model are here analyzed and compared for an industrial system. Furthermore, the effect of using backward Euler instead of forward Euler when discretizing the continuous time model is also analyzed. The ideas are evaluated using measurement data from a diesel engine. The engine is equipped with throttle, exhaust gas recirculation (EGR), and variable geometry turbines (VGT) and the stiff model dynamics arise as a consequence of the throttle between two control volumes in the air intake system. The process of simplifying and modifying the stiff ODE model to a DAE model is also discussed. The analysis of the computational effort shows that even though the ODE, for each time-update, is less computationally demanding than the resulting DAE, an EKF based on the DAE model achieves better estimation performance than one based on the ODE with less computational effort. The main gain with the DAE based EKF is that it allows increased step lengths without degrading the estimation performance compared to the ODE based EKF.

  • 209.
    Holmbom, Robin
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Liang, Bohan
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Boost Control with Turbo Speed Sensor and Electric Wastegate2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The purpose of this master thesis is to investigate the possibility to refine the control system of turbochargers in petrol engines by introducing turbo speed measurement. This thesis also investigates possible control enhancement from an electric wastegate actuator compared with a traditional pneumatic actuator. During the thesis work the control problem is divided into 3 sub systems: boost pressure controller, turbo speed controller, and electric actuator controller. The design procedure of the controllers follows model-based method in which a simulation model for engine and a simulation model for electric actuator are used. The designed controller is then implemented and evaluated in an engine test cell. The result of the thesis work shows that the electric wastegate actuator is preferred as it delivers consistent actuation speed and accurate positioning which favours model-based design that requires exact wastegate position. Although the purposed controller structure that uses turbo speed measurement cannot yet achieve faster generation of boost pressure by the end of the thesis work, the use of turbo speed sensor as controller feedback still shows potential to enhance the boost controller and ease the controller design, as the turbo speed measurement can reflect the boost pressure faster and is less sensitive to the disturbances in the air flow.

  • 210.
    Holmbom, Robin
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Liang, Bohan
    Volvo Car Corp, Sweden.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Implications of Using Turbocharger Speed Sensor for Boost Pressure Control2017Inngår i: IFAC PAPERSONLINE, ELSEVIER SCIENCE BV , 2017, Vol. 50, nr 1, s. 11040-11045Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Turbocharging is an important part of engine downsizing. Today, the control of the air charge system often consists of single-input single-output systems, where one input controls one output. With the increasing demand of lowering the emissions it is believed that solutions as long route exhaust gas recirculation and multiple stage turbocharging will be introduced for gasoline engines. This adds more actuators to the air charge system making it a multiple-input system. In the paper the implications of turbocharger speed measurement on the boost control system are investigated. A controller with turbo speed measurement, and one controller without is developed and implemented in a turbocharged inline four gasoline engine equipped with an electric servo-actuated wastegate in an engine test bench. The controllers ability to control the boost pressure is then discussed. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

  • 211.
    Holmbom, Robin
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Liang, Bohan
    Volvo Car Corporation.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Investigation of Performance Differences and Control Synthesis for Servo-Controlled and Vacuum-Actuated Wastegates2017Inngår i: SAE Technical Paper 2017-01-0592, SAE International , 2017, artikkel-id 2017-01-0592Konferansepaper (Fagfellevurdert)
    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.

  • 212.
    Holmer, Olov
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Simultaneous Reduction of Fuel Consumption and NOx Emissions through Hybridization of a Long Haulage Truck2017Inngår i: IFAC PAPERSONLINE, ELSEVIER SCIENCE BV , 2017, Vol. 50, nr 1, s. 8927-8932Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Hybridization is a promising and obvious way of reducing fuel consumption in automotive applications, however, its ability to reduce emissions in long haulage trucks is not so obvious. The complexity of the powertrain is also increased which makes well designed control systems needed to fully utilize the potential benefits of the hybridization. In this paper, a control strategy that takes advantage of the complex structure of the powertrain in a hybrid electric long haulage truck is developed and evaluated. The control system is based on equivalent consumption minimization strategy where an equivalence factor is used to compare fuel and battery power so that an optimal distribution of power between the components in the powertrain can be calculated. The proposed control system is evaluated in a driving scenario using a model of a complete hybrid electric truck, including an aftertreatment system, and the results are compared with a conventional, non-hybrid, vehicle. The hybridization leads to 31 % lower NOx emissions, primarily due to better thermal conditions in the exhaust system during braking, and at the same time, the fuel consumption was reduced by 3.8 % compared to the non-hybrid vehicle. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

  • 213.
    Häggblom, Johan
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Jerner, Jonathan
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Photovoltaic Power Production and Energy Storage Systems in Low-Voltage Power Grids2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In recent years, photovoltaic (PV) power production have seen an increase and the PV power systems are often located in the distribution grids close to the consumers. Since the distributions grids rarely are designed for power production, investigation of its effects is needed. It is seen in this thesis that PV power production will cause voltages to rise, potentially to levels exceeding the limits that grid owners have to abide by.

    A model of a distribution grid is developed in MathWorks MATLAB. The model contains a transformer, cables, households, energy storage systems (ESS:s) and photovoltaic power systems. The system is simulated by implementing a numerical Forward Backward Sweep Method, solving for powers, currents and voltages in the grid. PV power systems are added in different configurations along with different configurations of ESS:s. The results are analysed, primarily concerning voltages and voltage limits.

    It is concluded that addition of PV power production in the distribution grid affects voltages, more or less depending on where in the grid the systems are placed and what peak power they have. It is also concluded that having energy storage systems in the grid, changing the power factor of the inverter for the PV systems or lowering the transformer secondary-side voltage can bring the voltages down.

  • 214.
    Hägglund, Andreas
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Källgren, Moa
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Impact of Engine Dynamics on Optimal Energy Management Strategies for Hybrid Electric Vehicles2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In recent years, rules and regulations regarding fuel consumption of vehicles and the amount of emissions produced by them are becoming stricter. This has led the automotive industry to develop more advanced solutions to propel vehicles to meet the legal requirements. The Hybrid Electric Vehicle is one of the solutions that is becoming more popular in the automotive industry. It consists of an electrical driveline combined with a conventional powertrain, propelled by either a diesel or petrol engine. Two power sources create the possibility to choose when and how to use the power sources to propel the vehicle. The strategy that decides how this is done is referred to as an energy management strategy. Today most energy management strategies only try to reduce fuel consumption using models that describe the steady state behaviour of the engine. In other words, no reduction of emissions is achieved and all transient behaviour is considered negligible. 

    In this thesis, an energy management strategy incorporating engine dynamics to reduce fuel consumption and nitrogen oxide emissions have been designed. First, the models that describe how fuel consumption and nitrogen oxide emissions behave during transient engine operation are developed. Then, an energy management strategy is developed consisting of a model predictive controller that combines the equivalent consumption minimization strategy and convex optimization. Results indicate that by considering engine dynamics in the energy management strategy, both fuel consumption and nitrogen oxide emissions can be reduced. Furthermore, it is also shown that the major reduction in fuel consumption and nitrogen oxide emissions is achieved for short prediction horizons.

  • 215.
    Höckerdal, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Model Error Compensation in ODE and DAE Estimators: with Automotive Engine Applications2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Control and diagnosis of complex systems demand accurate information of the system state to enable efficient control and to detect system malfunction. Physical sensors are expensive and some quantities are hard or even impossible to measure with physical sensors. This has made model-based estimation an attractive alternative.

    Model based observers are sensitive to errors in the model and since the model complexity has to be kept low to enable use in real-time applications, the accuracy of the models becomes limited. Further, modeling is difficult and expensive with large efforts on model parametrization, calibration, and validation, and it is desirable to design robust observers based on existing models. An experimental investigation of an engine application shows that the model have stationary errors while the dynamics of the engine is well described by the model equations. This together with frequent appearance of sensor offsets have led to a demand for systematic ways of handling operating point dependent stationary errors, also called biases, in both models and sensors.

    Systematic design methods for reducing bias in model based observers are developed. The methods utilize a default model, described by systems of ordinary differential equations (ODE) or differential algebraic equations (DAE), and measurement data. A low order description of the model deficiencies is estimated from the default model and measurement data, which results in an automatic model augmentation. The idea is then to use the augmented model in observer design, yielding reduced stationary estimation errors compared to an observer based on the default model. Three main results are: a characterization of possible model augmentations from observability perspectives, a characterization of augmentations possible to estimate from measurement data, and a robustness analysis with respect to noise and model uncertainty.

    An important step is how the bias is modeled, and two ways of describing the bias are analyzed. The first is a random walk and the second is a parameterization of the bias. The latter can be viewed as an extension of the first and utilizes a parameterized function that describes the bias as a function of the operating point of the system. By utilizing a parameterized function, a memory is introduced that enables separate tracking of aging and operating point dependence. This eliminates the trade-off between noise suppression in the parameter convergence and rapid change of the offset in transients. Direct applications for the parameterized bias are online adaptation and offline calibration of maps commonly used in engine control systems.

    The methods are evaluated on measurement data from heavy duty diesel engines. A first order model augmentation is found for an ODE of an engine with EGR and VGT. By modeling the bias as a random walk, the estimation error is reduced by 50 % for a certification cycle. By instead letting a parameterized function describe the bias, better estimation accuracy and increased robustness is achieved. For an engine with intake manifold throttle, EGR, and VGT and a corresponding stiff ODE, experiments show that it is computationally beneficial to approximate the fast dynamics with instantaneous relations, transforming the ODE into a DAE. A main advantage is the possibility to use more than 10 times longer step lengths for the DAE based observer, without loss of estimation accuracy. By augmenting the DAE, an observer that achieves a 55 % reduction of the estimation error during a certification cycle is designed.

    Delarbeid
    1. Observer design and model augmentation for bias compensation with a truck engine application
    Åpne denne publikasjonen i ny fane eller vindu >>Observer design and model augmentation for bias compensation with a truck engine application
    2009 (engelsk)Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 17, nr 3, s. 408-417Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A systematic design method for reducing bias in observers is developed. The method utilizes an observable default model of the system together with measurement data from the real system and estimates a model augmentation. The augmented model is then used to design an observer which reduces the estimation bias compared to an observer based on the default model. Three main results are a characterization of possible augmentations from observability perspectives, a parameterization of the augmentations from the method, and a robustness analysis of the proposed augmentation estimation method. The method is applied to a truck engine where the resulting augmented observer reduces the estimation bias by 50% in a European transient cycle.

    Emneord
    Bias compensation, EKF, Non-linear, Observer
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-17160 (URN)10.1016/j.conengprac.2008.09.004 (DOI)
    Merknad
    Original Publication:Erik Höckerdal, Erik Frisk and Lars Eriksson, Observer design and model augmentation for bias compensation with a truck engine application, 2009, CONTROL ENGINEERING PRACTICE, (17), 3, 408-417.http://dx.doi.org/10.1016/j.conengprac.2008.09.004Copyright: Elsevier Science B.V., Amsterdam.http://www.elsevier.com/Tilgjengelig fra: 2009-03-19 Laget: 2009-03-07 Sist oppdatert: 2018-01-30bibliografisk kontrollert
    2. EKF-Based Adaptation of Look-Up Tables with an Air Mass-Flow Sensor Application
    Åpne denne publikasjonen i ny fane eller vindu >>EKF-Based Adaptation of Look-Up Tables with an Air Mass-Flow Sensor Application
    2011 (engelsk)Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 19, nr 5, s. 442-453Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A method for bias compensation and online map adaptation using extended Kalman filters isdeveloped. Key properties of the approach include the methods of handling component aging, varyingmeasurement quality including operating-point-dependent reliability and occasional outliers, andoperating-point-dependent model quality. Theoretical results about local and global observability,specifically adapted to the map adaptation problem, are proven. In addition, a method is presented tohandle covariance growth of locally unobservable modes, which is inherent in the map adaptationproblem. The approach is also applicable to the offline calibration of maps, in which case the onlyrequirement of the data is that the entire operating region of the system is covered, i.e., no specialcalibration cycles are required. The approach is applied to a truck engine in which an air mass-flowsensor adaptation map is estimated during a European transient cycle. It is demonstrated that themethod manages to find a map describing the sensor error in the presence of model errors on ameasurement sequence not specifically designed for adaptation. It is also demonstrated that themethod integrates well with traditional engineering tools, allowing prior knowledge about specificmodel errors to be incorporated and handled.

    sted, utgiver, år, opplag, sider
    Elsevier, 2011
    Emneord
    Bias compensation, EKF, Parameter estimation, Map adaptation
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-67591 (URN)10.1016/j.conengprac.2011.01.006 (DOI)000290744300003 ()
    Tilgjengelig fra: 2011-04-18 Laget: 2011-04-18 Sist oppdatert: 2018-01-30
    3. Off- and On-Line Identification of Maps Applied to the Gas Path in Diesel Engines
    Åpne denne publikasjonen i ny fane eller vindu >>Off- and On-Line Identification of Maps Applied to the Gas Path in Diesel Engines
    2012 (engelsk)Inngår i: Lecture notes in control and information sciences, ISSN 0170-8643, E-ISSN 1610-7411, Vol. 418, s. 241-256Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Maps or look-up tables are frequently used in engine control systems, and can be of dimension one or higher. Their use is often to describe stationary phenomena such as sensor characteristics or engine performance parameters like volumetric efficiency. Aging can slowly change the behavior, which can be manifested as a bias, and it can be necessary to adapt the maps. Methods for bias compensation and on-line map adaptation using extended Kalman filters are investigated and discussed. Key properties of the approach are ways of handling component aging, varying measurement quality, as well as operating point dependent model quality. Handling covariance growth on locally unobservable modes, which is an inherent property of the map adaptation problem, is also important and this is solved for the Kalman filter. The method is applicable to off-line calibration ofmaps where the only requirement of the data is that the entire operating region of the system is covered, i.e. no special calibration cycles are required. Two truck engine applications are evaluated, one where a 1-D air mass-ffow sensoradaptation map is estimated, and one where a 2-D volumetric efficiency map is adapted, both during a European transient cycle. An evaluation on experimental data shows that the method estimates a map, describing the sensor error, on a measurement sequence not specially designed for adaptation.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-67595 (URN)10.1007/978-1-4471-2221-0_14 (DOI)000306990500014 ()
    Konferanse
    Workshop on Identification for Automotive Systems, Johannes Kepler University Linz, Austria, July 15th - 16th
    Tilgjengelig fra: 2011-04-18 Laget: 2011-04-18 Sist oppdatert: 2018-01-30bibliografisk kontrollert
    4. DAE and ODE Based EKF:s and their Real-Time Performance Evaluated on a Diesel Engine
    Åpne denne publikasjonen i ny fane eller vindu >>DAE and ODE Based EKF:s and their Real-Time Performance Evaluated on a Diesel Engine
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    When estimating states in engine control systems there are limitations on the computational capabilities.This becomes especially apparent when designingobservers for stiff systems since the implementation requires small step lengths. One way to reduce the computational burden, is to reduce the model stiffness by approximating the fast dynamics with instantaneous relations, transformingan ODE model into a DAE model.

    Performance and sample frequency limitations for extended Kalman filters based on both the original ODE model and the reduced DAE model for a diesel engine is analyzed and compared. The effect of using backward Euler instead of forward Euler when discretizing the continuous time model is analyzed.

    The ideas are evaluated using measurement data from a diesel engine.The engine is equipped with throttle, EGR, and VGT and the stiff model dynamics arise as a consequence of the throttle between two control volumes in the air intake system. It is shown that even though the ODE, for each time-update, is less computationally demanding than the resulting DAE, an EKF based on the DAE model achieves better estimation performance than one based on the ODE with less computational effort. The main gain with the DAE based EKF is that it allows increased step lengths without degrading the estimation performance compared to the ODE based EKF.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-67596 (URN)
    Tilgjengelig fra: 2011-04-18 Laget: 2011-04-18 Sist oppdatert: 2018-01-30
    5. Bias Reduction in DAE Estimators by Model Augmentation: Observability Analysis and Experimental Evaluation
    Åpne denne publikasjonen i ny fane eller vindu >>Bias Reduction in DAE Estimators by Model Augmentation: Observability Analysis and Experimental Evaluation
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    A method for bias compensation in model based estimation utilizing model augmentation is developed. Based on a default model, that suffers from stationary errors, and measurements from the system a low order augmentation is estimated. The method handles models described by differential algebraic equations and the main contributions are necessary and sufficient conditions for the preservation of the observability properties of the default model during the augmentation.

    A characterization of possible augmentations found through the estimation, showing the benefits of adding extra sensors during the design, is included. This enables reduction of estimation errors also in states not used for feedback, which is not possible with for example PI-observers. Beside the estimated augmentation the method handles user provided augmentations, found through e.g. physical knowledge of the system.

    The method is evaluated on a nonlinear engine model where its ability to incorporate information from additional sensors during the augmentation estimationis clearly illustrated. By applying the method the mean relative estimation error for the exhaust manifold pressure is reduced by 55 %.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-67597 (URN)10.1109/CDC.2011.6160697 (DOI)
    Tilgjengelig fra: 2011-04-18 Laget: 2011-04-18 Sist oppdatert: 2018-01-30bibliografisk kontrollert
  • 216.
    Höckerdal, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Observer Design and Model Augmentation for Bias Compensation with Engine Applications2009Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Control and diagnosis of complex systems demand accurate knowledge of certain quantities to be able to control the system efficiently and also to detect small errors. Physical sensors are expensive and some quantities are hard or even impossible to measure with physical sensors. This has made model-based estimation an attractive alternative.

    Model-based estimators are sensitive to errors in the model and since the model complexity needs to be kept low, the accuracy of the models becomes limited. Further, modeling is hard and time consuming and it is desirable to design robust estimators based on existing models. An experimental investigation shows that the model deficiencies in engine applications often are stationary errors while the dynamics of the engine is well described by the model equations. This together with fairly frequent appearance of sensor offsets have led to a demand for systematic ways of handling stationary errors, also called bias, in both models and sensors.

    In the thesis systematic design methods for reducing bias in estimators are developed. The methods utilize a default model and measurement data. In the first method, a low order description of the model deficiencies is estimated from the default model and measurement data, resulting in an automatic model augmentation. The idea is then to use the augmented model for estimator design, yielding reduced stationary estimation errors compared to an estimator based on the default model. Three main results are: a characterization of possible model augmentations from observability perspectives, an analysis of what augmentations that are possible to estimate from measurement data, and a robustness analysis with respect to noise and model uncertainty.

    An important step is how the bias is modeled, and two ways of describing the bias are introduced. The first is a random walk and the second is a parameterization of the bias. The latter can be viewed as an extension of the first and utilizes a parameterized function that describes the bias as a function of the operating point of the system. The parameters, rather than the bias, are now modeled as random walks, which eliminates the trade-off between noise suppression in the parameter convergence and rapid change of the offset in transients. This is achieved by storing information about the bias in different operating points. A direct application for the parameterized bias is the adaptation algorithms that are commonly used in engine control systems.

    The methods are applied to measurement data from a heavy duty diesel engine. A first order model augmentation is found for a third order model and by modeling the bias as a random walk, an estimation error reduction of 50\,\% is achieved for a European transient cycle. By instead letting a parameterized function describe the bias, simulation results indicate similar, or better, improvements and increased robustness.

  • 217.
    Höckerdal, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Eriksson, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Frisk, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Air mass-flow measurement and estimation in diesel engines equipped with EGR and VGT2008Inngår i: International Journal of Passenger Cars - Electronic and Electrical Systems, ISSN 1946-4622, Vol. 1, nr 1, s. 393-402Artikkel i tidsskrift (Fagfellevurdert)
  • 218.
    Höckerdal, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Eriksson, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Frisk, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Air mass-flow measurement and estimation in diesel engines equipped with EGR and VGT2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    With stricter emission legislations and customer demands on low fuel consumption, good control strategies are necessary. This may involve control of variables that are hard, or even impossible, to measure with real physical sensors. By applying estimators or observers, these variables can be made available. The quality of a real sensor is determined by e.g. accuracy, drift and aging, but assessing the quality of an estimator is a more subtle task. An estimator is the result of a design work and hence, connected to factors like application, model, control error and robustness.

    The air mass-flow in a diesel engine is a very important quantity that has a direct impact on many control and diagnosis functions. The quality of the air mass-flow sensor in a diesel engine is analyzed with respect to day-to-day variations, aging, and differences in engine configurations. The investigation highlights the necessity of continuous monitoring and adaption of the air mass-flow. One way to do this is to use an estimator. Nine estimators are designed for estimation of the air mass-flow with the aim of assessing different quality measures. In the study of the estimators and quality measures it is evident that model accuracy is important and that special care has to be taken, regarding what quality measure to use, when the estimator performance is evaluated.

  • 219.
    Höckerdal, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Off- and On-Line Identification of Maps Applied to the Gas Path in Diesel Engines2012Inngår i: Lecture notes in control and information sciences, ISSN 0170-8643, E-ISSN 1610-7411, Vol. 418, s. 241-256Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Maps or look-up tables are frequently used in engine control systems, and can be of dimension one or higher. Their use is often to describe stationary phenomena such as sensor characteristics or engine performance parameters like volumetric efficiency. Aging can slowly change the behavior, which can be manifested as a bias, and it can be necessary to adapt the maps. Methods for bias compensation and on-line map adaptation using extended Kalman filters are investigated and discussed. Key properties of the approach are ways of handling component aging, varying measurement quality, as well as operating point dependent model quality. Handling covariance growth on locally unobservable modes, which is an inherent property of the map adaptation problem, is also important and this is solved for the Kalman filter. The method is applicable to off-line calibration ofmaps where the only requirement of the data is that the entire operating region of the system is covered, i.e. no special calibration cycles are required. Two truck engine applications are evaluated, one where a 1-D air mass-ffow sensoradaptation map is estimated, and one where a 2-D volumetric efficiency map is adapted, both during a European transient cycle. An evaluation on experimental data shows that the method estimates a map, describing the sensor error, on a measurement sequence not specially designed for adaptation.

  • 220.
    Höckerdal, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Eriksson , Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Observer design and model augmentation for bias compensation with a truck engine application2009Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 17, nr 3, s. 408-417Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A systematic design method for reducing bias in observers is developed. The method utilizes an observable default model of the system together with measurement data from the real system and estimates a model augmentation. The augmented model is then used to design an observer which reduces the estimation bias compared to an observer based on the default model. Three main results are a characterization of possible augmentations from observability perspectives, a parameterization of the augmentations from the method, and a robustness analysis of the proposed augmentation estimation method. The method is applied to a truck engine where the resulting augmented observer reduces the estimation bias by 50% in a European transient cycle.

  • 221.
    Höckerdal, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Bias Reduction in DAE Estimators by Model Augmentation: Observability Analysis and Experimental EvaluationManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    A method for bias compensation in model based estimation utilizing model augmentation is developed. Based on a default model, that suffers from stationary errors, and measurements from the system a low order augmentation is estimated. The method handles models described by differential algebraic equations and the main contributions are necessary and sufficient conditions for the preservation of the observability properties of the default model during the augmentation.

    A characterization of possible augmentations found through the estimation, showing the benefits of adding extra sensors during the design, is included. This enables reduction of estimation errors also in states not used for feedback, which is not possible with for example PI-observers. Beside the estimated augmentation the method handles user provided augmentations, found through e.g. physical knowledge of the system.

    The method is evaluated on a nonlinear engine model where its ability to incorporate information from additional sensors during the augmentation estimationis clearly illustrated. By applying the method the mean relative estimation error for the exhaust manifold pressure is reduced by 55 %.

  • 222.
    Höckerdal, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Frisk, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Bias Reduction in DAE Estimators by Model Augmentation: Observability Analysis and Experimental Evaluation2011Inngår i: 50th IEEE Conference on Decision and Control and European Control Conference (CDC-ECC), 2011, Institute of Electrical and Electronics Engineers (IEEE), 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A method for bias compensation in model based estimation utilizing model augmentation is developed. Based on a default model, that suffers from stationary errors, and measurements from the system a low order augmentation is estimated. The method handles models described by differential algebraic equations and the main contributions are necessary and sufficient conditions for the preservation of the observability properties of the default model during the augmentation.

  • 223.
    Höckerdal, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Bias Reduction in DAE Estimators by Model Augmentation: Observability Analysis and Experimental Evaluation2011Inngår i: 50th IEEE Conference on Decision and Control and European Control Conference (CDC-ECC), 2011, Institute of Electrical and Electronics Engineers (IEEE), 2011, s. 7446-7451Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A method for bias compensation in model based estimation utilizing model augmentation is developed. Based on a default model, that suffers from stationary errors, and measurements from the system a low order augmentation is estimated. The method handles models described by differential algebraic equations and the main contributions are necessary and sufficient conditions for the preservation of the observability properties of the default model during the augmentation. A characterization of possible augmentations found through the estimation, showing the benefits of adding extra sensors during the design, is included. This enables reduction of estimation errors also in states not used for feedback, which is not possible with for example PI-observers. Beside the estimated augmentation the method handles user provided augmentations, found through e.g. physical knowledge of the system. The method is evaluated on a nonlinear engine model where its ability to incorporate information from additional sensors during the augmentation estimation is clearly illustrated. By applying the method the mean relative estimation error for the exhaust manifold pressure is reduced by 55%.

  • 224.
    Höckerdal, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    DAE and ODE Based EKF:s and their Real-Time Performance Evaluated on a Diesel EngineManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    When estimating states in engine control systems there are limitations on the computational capabilities.This becomes especially apparent when designingobservers for stiff systems since the implementation requires small step lengths. One way to reduce the computational burden, is to reduce the model stiffness by approximating the fast dynamics with instantaneous relations, transformingan ODE model into a DAE model.

    Performance and sample frequency limitations for extended Kalman filters based on both the original ODE model and the reduced DAE model for a diesel engine is analyzed and compared. The effect of using backward Euler instead of forward Euler when discretizing the continuous time model is analyzed.

    The ideas are evaluated using measurement data from a diesel engine.The engine is equipped with throttle, EGR, and VGT and the stiff model dynamics arise as a consequence of the throttle between two control volumes in the air intake system. It is shown that even though the ODE, for each time-update, is less computationally demanding than the resulting DAE, an EKF based on the DAE model achieves better estimation performance than one based on the ODE with less computational effort. The main gain with the DAE based EKF is that it allows increased step lengths without degrading the estimation performance compared to the ODE based EKF.

  • 225.
    Höckerdal, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    EKF-Based Adaptation of Look-Up Tables with an Air Mass-Flow Sensor Application2011Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 19, nr 5, s. 442-453Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method for bias compensation and online map adaptation using extended Kalman filters isdeveloped. Key properties of the approach include the methods of handling component aging, varyingmeasurement quality including operating-point-dependent reliability and occasional outliers, andoperating-point-dependent model quality. Theoretical results about local and global observability,specifically adapted to the map adaptation problem, are proven. In addition, a method is presented tohandle covariance growth of locally unobservable modes, which is inherent in the map adaptationproblem. The approach is also applicable to the offline calibration of maps, in which case the onlyrequirement of the data is that the entire operating region of the system is covered, i.e., no specialcalibration cycles are required. The approach is applied to a truck engine in which an air mass-flowsensor adaptation map is estimated during a European transient cycle. It is demonstrated that themethod manages to find a map describing the sensor error in the presence of model errors on ameasurement sequence not specifically designed for adaptation. It is also demonstrated that themethod integrates well with traditional engineering tools, allowing prior knowledge about specificmodel errors to be incorporated and handled.

  • 226.
    Höckerdal, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Scania CV AB, Södertälje, Sweden.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Model Based Engine Map Adaptation Using EKF2010Inngår i: Proceedings of 6th IFAC Symposium on Advances in Automotive Control, IFAC Papers Online, 2010, Vol. 43, s. 697-702Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A method for online map adaptation is developed. The method utilizes the EKF as a parameter estimator and handles parameter aging, operating point dependent model and measurement quality. Map adaptation, by construction, gives marginally stable models with locally unobservable modes, that are handled. The method is also suitable for offline calibration of maps where the only requirement of the data is that the entire operating region of the system is covered. The method is applied to a truck engine where an air mass-flow sensor adaptation map is estimated based on data from a diesel engine during an ETC. It is shown that an adaptation map can be found in a measurement sequence not specially designed for adaptation.

  • 227.
    Höckerdal, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Model Based Engine Map Adaptation Using EKF2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A method for on-line map adaptation is developed. The method utilizes the EKF as a parameter estimator and handles parameter aging, operating point dependent model and measurement quality. Map adaptation, by construction, gives marginally stable models with locally unobservable modes, that are handled. The method is also suitable for off-line calibration of maps where the only requirement of the data is that the entire operating region of the system is covered. The method is applied to a truck engine where an air mass-flow sensor adaptation map is estimated based on data from a diesel engine during an ETC. It is shown that an adaptation map can be found in a measurement sequence not specially designed for adaptation.

  • 228.
    Höckerdal, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Frisk, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Eriksson, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Observer Design and Model Augmentation for Bias Compensation Applied to an Engine2008Konferansepaper (Fagfellevurdert)
  • 229.
    Höglund, Filip
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Knock Detection in a Two-Stroke Engine to be Used in the Engine Management System2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Engine knock has long been a well recognized phenomenon in the automotive industry. Detecting engine knock opens up the possibility for an indirect feedback of the engine's internal combustion without installing a pressure transducer inside the cylinder. Knock detection has mainly been used for spark advance control, making it possible to control the engine close to its knock limit in search for the optimal ignition timing. This application has to a lesser extent been applied to lightweight two-stroke engines, which is the focus of this study. The investigation features a modern chainsaw engine whose knock characteristics were first determined with a pressure transducer. The structural vibrations originating from the engine knock are filtered out of the signal from a remote located accelerometer. The knock intensity is compared with the signal from the pressure transducer which shows a correlation with an accepted extent between the two sensors. Parameters that affect the knock intensity have also been investigated. These include engine temperature, different types of fuel and ignition timings.

  • 230.
    Irman, Svraka
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Linus, Österdahl Wetterhag
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Model Based Catalyst Control2019Independent thesis Advanced level (degree of Master (Two Years)), 300 hpOppgave
    Abstract [en]

    A one dimensional discretized model of a two brick three way catalyst (TWC) system was developed and implemented in MATLAB, Simulink and TargetLink in collaboration with Volvo Cars and Linköpings Universitet - ISY. The purpose of this thesis was to increase system understanding and create a model based TWC control for further development at Volvo Cars. A total of 50 states were modelled, including emission concentrations (O2, CO, C3H6, C3H8, H2, NOx, CO2, H2O), temperature and oxygen buffer level (OBL). A model based control structure was implemented in the form of five separate PID-controllers enabling possibilities to control the OBL of each separate slice of each brick individually and through simple reference handling. The control structures includes anti-windup, feedforward control and feedback safety for model reset during sensor indication of leakage. Specific equipment and software used included MATLAB, Simulink, TargetLink, Volvo SULEV30 TWC and testing rigs. Overall increase in system understanding was achieved in comparison with contemporary TWC modelling and control, as well as sufficient system performance in regard to estimate emissions, simulation duration and pedagogical value. Concluding thoughts of the thesis revolve the complexity of the actual TWC modelling, parameter estimation as well as control. The model presented in this thesis has great potential of describing TWC systems but with great effort during parameter estimation. With ECU performance available in temporary vehicle production year 2019, a complex model may be combined with a simple control strategy whilst a simple model may be combined with a complex control strategy.

  • 231.
    Isaksson, Olle
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Institutionen för systemteknik.
    Model-based Diagnosis of a Satellite Electrical Power System with RODON2009Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    As space exploration vehicles travel deeper into space, their distance to earth increases.The increased communication delays and ground personnel costs motivatea migration of the vehicle health management into space. A way to achieve thisis to use a diagnosis system. A diagnosis system uses sensor readings to automaticallydetect faults and possibly locate the cause of it. The diagnosis system usedin this thesis is a model-based reasoning tool called RODON developed by UptimeSolutions AB. RODON uses information of both nominal and faulty behavior ofthe target system mathematically formulated in a model.The advanced diagnostics and prognostics testbed (ADAPT) developed at theNASA Ames Research Center provides a stepping stone between pure researchand deployment of diagnosis and prognosis systems in aerospace systems. Thehardware of the testbed is an electrical power system (EPS) that represents theEPS of a space exploration vehicle. ADAPT consists of a controlled and monitoredenvironment where faults can be injected into a system in a controlled manner andthe performance of the diagnosis system carefully monitored. The main goal of thethesis project was to build a model of the ADAPT EPS that was used to diagnosethe testbed and to generate decision trees (or trouble-shooting trees).The results from the diagnostic analysis were good and all injected faults thataffected the actual function of the EPS were detected. All sensor faults weredetected except faults in temperature sensors. A less detailed model would haveisolated the correct faulty component(s) in the experiments. However, the goal wasto create a detailed model that can detect more than the faults currently injectedinto ADAPT. The created model is stationary but a dynamic model would havebeen able to detect faults in temperature sensors.Based on the presented results, RODON is very well suited for stationary analysisof large systems with a mixture of continuous and discrete signals. It is possibleto get very good results using RODON but in turn it requires an equally goodmodel. A full analysis of the dynamic capabilities of RODON was never conductedin the thesis which is why no conclusions can be drawn for that case.

     

  • 232.
    Ivarsson, Maria
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Fuel Optimal Powertrain Control for Heavy Trucks Utilizing Look Ahead2009Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The road topography in highways affects the powertrain control of a heavy truck substantially since the engine power is low in relation to the vehicle weight. In large road gradients constant speed is not possible to keep, which would have been beneficial otherwise, and in some uphills shifting gears becomes inevitable. If information about the road ahead, i.e. look ahead information, is available, then the powertrain can be controlled in a more fuel efficient way. Trial runs are performed, where the velocity trajectory that minimizes energy consumption, is calculated and communicated in real time as set points to the conventional cruise control. This look ahead control gives significant fuel consumption reductions compared to a standard cruise control, while keeping to the same mean speed. The results are the inspiration to further studies in how powertrain control can benefit from look ahead information. An engine with a non-linear fuel map is studied to understand its impact on fuel optimal speed. It is shown that for a significant fuel map non-linearity, quantified by a threshold value, constant speed in small road gradients is no longer optimal. Further, an automated manual transmission (AMT) optimal gear control is studied. It is shown that the reduced propulsion of a typical AMT gear-shifting process must be considered when choosing when to shift gears. Thus, additional reductions of fuel consumption are obtained with a look ahead control based on knowledge of engine and transmission characteristics.

    Delarbeid
    1. Look-ahead control for heavy trucks to minimize trip time and fuel consumption
    Åpne denne publikasjonen i ny fane eller vindu >>Look-ahead control for heavy trucks to minimize trip time and fuel consumption
    2009 (engelsk)Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 17, nr 2, s. 245-254Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The scenario studied is a drive mission for a heavy diesel truck. With aid of an on board road slope database in combination with a GPS unit, information about the road geometry ahead is extracted. This look-ahead information is used in an optimization of the velocity trajectory with respect to a criterion formulation that weighs trip time and fuel consumption. A dynamic programming algorithm is devised and used in a predictive control scheme by constantly feeding the conventional cruise controller with new set points. The algorithm is evaluated with a real truck on a highway, and the experimental results show that the fuel consumption is significantly reduced.

    Emneord
    predictive control, dynamic programming, fuel-optimal control
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-16629 (URN)10.1016/j.conengprac.2008.07.005 (DOI)
    Prosjekter
    CADICS
    Merknad

    Original Publication: Erik Hellström, Maria Ivarsson, Jan Åslund and Lars Nielsen, Look-ahead control for heavy trucks to minimize trip time and fuel consumption, 2009, Control Engineering Practice, (17), 2, 245-254. http://dx.doi.org/10.1016/j.conengprac.2008.07.005 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/

    Tilgjengelig fra: 2009-02-08 Laget: 2009-02-06 Sist oppdatert: 2018-01-13
    2. Look Ahead Control - Consequences of a Non-Linear Fuel Map on Truck Fuel Consumption
    Åpne denne publikasjonen i ny fane eller vindu >>Look Ahead Control - Consequences of a Non-Linear Fuel Map on Truck Fuel Consumption
    2008 (engelsk)Inngår i: The 17th IFAC World Congress, 2008Konferansepaper, Publicerat paper (Annet vitenskapelig)
    Abstract [en]

    Consequences of non-linearities in specific fuel consumption, sfc, of a heavy truck combustion engine are studied with focus on so small road gradients that constant speed is optimal if the engine torque has an affine relation to fueling. A quasi-static analysis gives valuable insights into the intrinsic properties of minimization of fuel consumption. Two objective functions are shown to give different optimal velocity trajectories on a constant road gradient, when the non-linearity in sfc is significant, a notation which is quantified. For a significant non-linearity, when a constraint is set to keep a final time, switching between two characteristic speeds is optimal. Alternatively, if consumed time, in addition to fuel consumption, is part of the objective function, then keeping to one constant speed is optimal also for significant non-linearities. However, the different optimal solutions still show similarities, since for a certain significant non-linearity a specific speed range determined by the characteristic velocities is shown to be unobtainable for both optimality criteria. Similar results are obtained for a full dynamic model including a realistic fuel map and other realistic constraints.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-18188 (URN)
    Konferanse
    The 17th IFAC World Congress
    Merknad

    This article is an extended version of (Ivarsson et al., 2008), Optimal Speed on Small Gradients – Consequences of a Non-Linear Fuel Map, presented at the IFAC World Congress 2008.

    Tilgjengelig fra: 2009-05-11 Laget: 2009-05-11 Sist oppdatert: 2013-02-27
    3. Impacts of AMT Gear-Shifting on Fuel Optimal Look Ahead Control
    Åpne denne publikasjonen i ny fane eller vindu >>Impacts of AMT Gear-Shifting on Fuel Optimal Look Ahead Control
    2009 (engelsk)Rapport (Annet vitenskapelig)
    Abstract [en]

    A fuel optimal gear shift control has been studied, when look ahead information is available, and the impact of the automated manual transmission (AMT) gear-shifting process is analayzed. For a standard discrete heavy truck transmission, answers are found on when to shift gears, prior to or when in an uphill slope. The gear-shifting process of a standard AMT is modeled, not considering the comfort details, in order to capture the fuel and time aspects of the gear shift. A numerical optimization is performed by dynamic programming, minimizing fuel consumption and time by controlling fuel injection and gear. Since a standard AMT does not have look ahead information, it sometimes gears down unnecessarily and thus gives a significantly higher fuel consumption compared to the optimal control. However, if gearing down is inevitable, the AMT gear-shifting strategy, based on engine thresholds, is a well-functioning gear control so that the optimal control only gives marginal additional savings. To attain the possible fuel reductions it is shown that the reduced propulsion of an AMT gear-shifting process, and the resulting vehicle retardation, must be considered. The point of shifting gears must be chosen to ensure an adequate engine speed in order to get a sufficient engine power after the gear shift, even as the truck is decelerated during gear shift.

    sted, utgiver, år, opplag, sider
    Linköping: Linköping University Electronic Press, 2009. s. 14
    Serie
    LiTH-ISY-R, ISSN 1400-3902 ; 2883
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-18189 (URN)LITH-ISY-R-2883 (ISRN)10.4271/2010-01-0370 (DOI)
    Tilgjengelig fra: 2009-05-11 Laget: 2009-05-11 Sist oppdatert: 2014-09-24bibliografisk kontrollert
  • 233.
    Ivarsson, Maria
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Åslund, Jan
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Impacts of AMT Gear-Shifting on Fuel Optimal Look Ahead Control2009Rapport (Annet vitenskapelig)
    Abstract [en]

    A fuel optimal gear shift control has been studied, when look ahead information is available, and the impact of the automated manual transmission (AMT) gear-shifting process is analayzed. For a standard discrete heavy truck transmission, answers are found on when to shift gears, prior to or when in an uphill slope. The gear-shifting process of a standard AMT is modeled, not considering the comfort details, in order to capture the fuel and time aspects of the gear shift. A numerical optimization is performed by dynamic programming, minimizing fuel consumption and time by controlling fuel injection and gear. Since a standard AMT does not have look ahead information, it sometimes gears down unnecessarily and thus gives a significantly higher fuel consumption compared to the optimal control. However, if gearing down is inevitable, the AMT gear-shifting strategy, based on engine thresholds, is a well-functioning gear control so that the optimal control only gives marginal additional savings. To attain the possible fuel reductions it is shown that the reduced propulsion of an AMT gear-shifting process, and the resulting vehicle retardation, must be considered. The point of shifting gears must be chosen to ensure an adequate engine speed in order to get a sufficient engine power after the gear shift, even as the truck is decelerated during gear shift.

  • 234.
    Ivarsson, Maria
    et al.
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Åslund, Jan
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Look Ahead Control - Consequences of a Non-Linear Fuel Map on Truck Fuel Consumption2008Inngår i: The 17th IFAC World Congress, 2008Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Consequences of non-linearities in specific fuel consumption, sfc, of a heavy truck combustion engine are studied with focus on so small road gradients that constant speed is optimal if the engine torque has an affine relation to fueling. A quasi-static analysis gives valuable insights into the intrinsic properties of minimization of fuel consumption. Two objective functions are shown to give different optimal velocity trajectories on a constant road gradient, when the non-linearity in sfc is significant, a notation which is quantified. For a significant non-linearity, when a constraint is set to keep a final time, switching between two characteristic speeds is optimal. Alternatively, if consumed time, in addition to fuel consumption, is part of the objective function, then keeping to one constant speed is optimal also for significant non-linearities. However, the different optimal solutions still show similarities, since for a certain significant non-linearity a specific speed range determined by the characteristic velocities is shown to be unobtainable for both optimality criteria. Similar results are obtained for a full dynamic model including a realistic fuel map and other realistic constraints.

  • 235.
    Ivarsson, Maria
    et al.
    Scania CV AB.
    Åslund, Jan
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Look-ahead control – consequences of a non-linear fuel map on truck fuel consumption2009Inngår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering, ISSN 0954-4070, E-ISSN 2041-2991, Vol. 223, nr 10, s. 1223-1238Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Consequences of non-linearities in specific fuel consumption (SFC) of a heavy truck combustion engine are studied with focus on such small road gradients that a constant speed is optimal if the engine torque has an affine relation to fuelling. A quasi-static analysis gives valuable insights into the intrinsic properties of minimization of fuel consumption. Two objective functions are shown to give different optimal velocity trajectories on a constant road gradient, when the non-linearity in SFC is significant, a notation which is quantified. For a significant non-linearity, when a constraint is set to keep a final time, switching between twocharacteristic speeds is optimal. Alternatively, if consumed time, in addition to fuel consumption, is part of the objective function, then keeping to one constant speed is optimal also for significant non-linearities. However, the different optimal solutions still show similarities, since for a certain significant non-linearity a specific speed range determined by the characteristic velocities is shown to be unobtainable for both optimality criteria. Similarresults are obtained for a full dynamic model including a realistic fuel map and other realistic constraints.

  • 236.
    Jakobsson, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten. Atlas Copco Rock Drills AB, Örebro, Sweden.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Pettersson, Robert
    Atlas Copco Rock Drills AB, Örebro, Sweden.
    Krysander, Mattias
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Data driven modeling and estimation of accumulated damage in mining vehicles using on-board sensors2017Inngår i: PHM 2017. Proceedings of the Annual Conference of the Prognostics and Health Management Society 2017, St. Petersburg, Florida, USA, October 2–5, 2017 / [ed] Anibal Bregon and Matthew J. Daigle, phmSociety , 2017, s. 98-107Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The life and condition of a MT65 mine truck frame is to a large extent related to how the machine is used. Damage from different stress cycles in the frame are accumulated over time, and measurements throughout the life of the machine are needed to monitor the condition. This results in high demands on the durability of sensors used. To make a monitoring system cheap and robust enough for a mining application, a small number of robust sensors are preferred rather than a multitude of local sensors such as strain gauges. The main question to be answered is whether a low number of robust on-board sensors can give the required information to recreate stress signals at various locations of the frame. Also the choice of sensors among many different locations and kinds are considered. A final question is whether the data could also be used to estimate road condition. By using accelerometer, gyroscope and strain gauge data from field tests of an Atlas Copco MT65 mine truck, coherence and Lasso-regression were evaluated as means to select which signals to use. ARX-models for stress estimation were created using the same data. By simulating stress signals using the models, rain flow counting and damage accumulation calculations were performed. The results showed that a low number of on-board sensors like accelerometers and gyroscopes could give enough information to recreate some of the stress signals measured. Together with a linear model, the estimated stress was accurate enough to evaluate the accumulated fatigue damage in a mining truck. The accumulated damage was also used to estimate the condition of the road on which the truck was traveling. To make a useful road monitoring system some more work is required, in particular regarding how vehicle speed influences damage accumulation.

  • 237.
    Jia Wei Tang, Samuel
    et al.
    Monash University, Australia.
    Ng, Kok Yew
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten. Monash University, Malaysia.
    Khoo, BH
    Monash University, Malaysia.
    Parkkinen, Jussi
    University of Eastern Finland, Finland.
    Real-Time Lane Detection and Rear-End Collision Warning System On A Mobile Computing Platform2015Inngår i: 39TH ANNUAL IEEE COMPUTERS, SOFTWARE AND APPLICATIONS CONFERENCE (COMPSAC 2015), VOL 2, IEEE , 2015, s. 563-568Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Accident prevention systems have recently been a part of many modern cars to reduce injuries and casualties on the road. However, the high cost of components and equipment have limited such safety systems to higher-end and luxury vehicles. This paper proposes an economical method of using a smartphone application for real-time lane detection and rear-end collision warning system for drivers on the road. The Android-based application uses image-processing algorithms coupled with the monoscopic camera on the smartphone as the main sensor to perform lane and vehicle detections. The novelty of this work lies in the use of the monocular vision of the camera to estimate the distance with the vehicle up ahead. The system is able to distinguish unintentional lane departure and if the driver is traveling too close to the vehicle ahead. An acoustic warning will notify the driver of a potential accident.

  • 238.
    Johansson, Andreas
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Kvaldén, Daniel
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Prestandaförbättring på en semiaktiv dämpare genom förbättrad reglering2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Hydrauliska stötdämpare har länge varit en central komponent på både bilar och motorcyklar. Stötdämpare påverkar fordonets komfort, väghållning och köregenskaper. Dessa olika egenskaper kräver ofta helt olika typer av dämpning och med vanliga passiva dämpare blir resultatet ofta en kompromiss av samtliga dessa. Kompromisserna har lett till utvecklingen av en stötdämpare med ställbar dämparkarakteristik som är tänkt att ersätta passiva dämpare. Öhlins Racing säljer idag ett semiaktivt stötdämparsystem som kallas CES, Continously controlled Electronic Suspension, där dämparkarakteristiken styrs av en tryck- och flödeskompenserad CES-ventil. CES-ventilen är strömstyrd via en ECU, Electronic Control Unit, som monteras på fordonet. Möjligheterna att förbättra fordonens egenskaper är stora men regleringen av dämparen är kritisk för prestandan.

    Examesarbetet syftar till att via experimentella laborationstester förbättra dämparens prestanda genom att förbättra styrningen av systemet. Det visar sig att den nuvarande reglersystemet lider av en tidsfördröjning, varför en stor del av examensarbetet fokuserar på att minimera detta.

    Resultaten visar att då hastigheten skattas med ett Kalmanfilter, som tar hänsyn till både dämparens position och acceleration, kan tidsfördröjningar nästan helt elimineras. Elimineringen av tidsfördröjning visar sig förbättra prestandan avsevärt. För att ytterligare öka prestandan hos systemet introduceras även en accelerationsframkoppling.

  • 239.
    Johansson, Anton
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Drangel, Martin
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Measurements and Modelling for Heat Transfer Corrected Exhaust Gas Temperatures in a Gasoline Engine2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis is treating the modelling of a thermocouple (tc) to compensate forheat transfers due to convection, radiation and conduction when performingtemperature measurements in an SI-engine. An experiment plan was developedwhich covered experiments in an stc-rig and on a 4-cylinder SI-engine. The measurementsin the stc-rig was mainly to develop the model, while the measurementsin the engine lab was mainly to examine the characteristics of the engineand evaluate the modelled tc.Measurements with an exposed thin tip tc in the stc-rig showed a symmetricaltemperature profile in the pipe. By examining how the 1.5 mm tc behaved inthis environment with known gas temperature profile, the obtained knowledgecould be applied to cross-sectional measurements in the SI-engine. It was foundthat the temperature profile in the engine deviated from the temperature profilemeasured in the stc-rig. The temperature was higher near the top of the pipethan in the center and lower part. In the horizontal direction, the temperaturewas found to be constant.Conclusions drawn from measurements in the engine lab points to that the crosssectionaltemperature and mass flow profiles have a strong connection with theengine’s operation point. The cross-sectional profiles, along with respective profileover time, is crucial when estimating the energy content of an exhaust gaspulse.The inverted sensor model with optimized parameters could estimate the meanvalue of the measured gas temperature during stationary runs within 6 degC.

  • 240.
    Johansson, Henrik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Evaluation of Communication Interfaces for ElectronicControl Units in Heavy-duty Vehicles2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The number of electronic control units in heavy-duty vehicles has grown dramatically overthe last few decades. This has led to the use of communication buses to reduce the complexityand weight of the networks. There are reasons to believe that the de facto standardcommunication interface in the automotive industry, the Controller Area Network, is obsoletein some areas. Hence an evaluation of available communication interfaces is needed.This study focuses on lower levels of the Open Systems Interconnect (osi) model. Initially atheoretical study is presented in order to give an overview of automotive embedded systemsin general and different communication interfaces in particular. Ethernet and FlexRay areidentified as two interfaces of interest for future use in Scanias vehicles. The former is new inautomotive applications but is believed to become popular over the years to come. A possibleuse of this interface could be as a backbone to take the load off other interfaces. The use ofFlexRay in Scanias vehicles is limited because of the modular system used and the staticscheduling needed. It could however be used between mandatory ecus where the nodes andthe messages are all known beforehand.The report also contains the result from emission measurements on a number of interfacesperformed using a stripline antenna in a shielded enclosure. Strong conclusions can not bedrawn since it’s hard to tell what the transceivers, circuit boards and interfaces contributedto in the spectra with the method used. The FlexRay hardware is worse than for the otherinterfaces. Similarities can be seen between low-speed and high-speed can but it could becharacteristics of the transceivers used rather than the interface itself.

  • 241.
    Johansson, Linus
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Full Cycle Cylinder State Estimation in DI Engines with VVA2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    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.

  • 242.
    Johansson, Max
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Optimal Control of Heat Transfer Rates in Turbochargers2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 243.
    Johansson, Max
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Ekberg, Kristoffer
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Time Optimal Turbocharger Testing in Gas Stands with a Known Map2018Inngår i: IFAC PAPERSONLINE, ELSEVIER SCIENCE BV , 2018, Vol. 51, nr 31, s. 868-875Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Turbocharger maps are used in design, evaluation and optimization of engine system operation to represent the turbo operation in different scenarios. To construct such a map, the turbo is tested in a gas flow test bench, called gas stand. Turbo testing is a time and resource consuming experimental process. The turbo is tested in a selected number of test points for different turbo rotational speeds, where the temperatures in the turbo have to be stationary when the measurements that constitute the map are acquired. In this paper, optimal control is used to find the most time efficient pattern of test conditions, and the optimal control strategy to traverse between them. A heat transfer model, describing the heat transfer between the compressor, bearing house, and turbine, is presented and validated against measured data. A direct collocation method is used to find time optimal control trajectories between the specified test points in the map. The method objective is to find the least time consuming control strategy which brings the turbo from one test point to the next, while ensuring thermal equilibrium at the final time. The results suggest that this method reduces turbocharger testing time with a factor higher than 60. The improvements can be further increased, with over 70 times, if a traveling salesman problem is solved to find the optimal route through the turbo map. The described method would be able to map a 43 points turbo map in 22 minutes, including a 5 minute warm-up phase. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

  • 244.
    Johansson, Tobias
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Virtual Sensors for Combustion Parameters Based on In-Cylinder Pressure2015Independent thesis Advanced level (degree of Master (Two Years)), 300 hpOppgave
    Abstract [en]

    Typically the combustion in engines are open-loop controlled. By using an in-cylinder pressure sensor it is possible to create virtual sensors for closed-loop combustion control (CLCC). With CLCC it is possible to counteract dynamic effects as component ageing, fuel type and cylinder variance.

    A virtual sensor system was implemented based on a one-zone heat-release analysis, including signal processing of the pressure sensor input. A parametrisation of the heat-release based on several Vibe functions was implemented with good results.

    The major focus of the virtual sensor system was to perform a tolerance analysis on experimental data, where typical error sources in a production heavy-duty vehicle were identified and their effect on the estimates quantified. It could be concluded that estimates are very much dependent on the choice of heat-release and specific heat ratio models. Especially crank angle phasing has a large impact on estimation performance, stressing the importance of accounting for crankshaft torsion in production vehicles. Biodiesel advances the combustion angle and give a lower IMEP and total heat amount compared to standard diesel. However, error sensitivity is not affected.

    Further investigations must be made on improving the signal processing in terms of gain error compensation and filtering. Also a better understanding of how errors propagate between subsystems in a CLCC system is required for successful implementation.

  • 245.
    Jonsson Holm, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Vehicle Mass and Road Grade Estimation Using Kalman Filter2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This Master's thesis presents a method for on-line estimation of vehicle mass and road grade using Kalman filter. Many control strategies aiming for better fuel economy, drivability and safety in today's vehicles rely on precise vehicle operating information. In this context, vehicle mass and road grade are crucial parameters. The method is based on an extended Kalman filter (EKF) and a longitudinal vehicle model. The main advantage of this method is its applicability on drivelines with continuous power output during gear shifts and cost effectiveness compared to hardware solutions. The performance has been tested on both simulated data and on real measurement data, collected with a truck on road. Two estimators were developed; one estimates both vehicle mass and road grade and the other estimates only vehicle mass using an inclination sensor as an additional measurement. Tests of the former estimator demonstrate that a reliable mass estimate with less than 5 % error is often achievable within 5 minutes of driving. Furthermore, the root mean square error of the grade estimate is often within 0.5°. Tests of the latter estimator show that this is more accurate and robust than the former estimator with a mass error often within 2 %. A sensitivity analysis shows that the former estimator is fairly robust towards minor modelling errors. Also, an observability analysis shows under which circumstances simultaneous vehicle mass and road grade is possible.

  • 246.
    Juhlin, Olof
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Modeling of Battery Degradation in Electrified Vehicles2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis provides an insight into battery modeling in electric vehicles which includes degradation mechanisms as in automotive operation in electric vehicles. As electric vehicles with lithium ion batteries increase in popularity there is an increased need to study and model the capacity losses in such batteries. If there is a good understanding of the phenomena involved and an ability to predict these losses there is also a foundation to take measures to minimize these losses.

    In this thesis a battery model for lithium ion batteries which includes heat dissipation is used as groundwork. This model is expanded with the addition of capacity losses due to usage as well as storage. By combining this with a simple vehicle model one can use these models to achieve an understanding as to how a battery or pack of several batteries would behave in a specific driving scenario. Much of the focus in the thesis is put into comparing the different factors of degradation to highlight what the major contributors are.

    The conclusion is drawn that heat is the main cause for degradation for batteries in electric vehicles. This applies for driving usage as well as during storage. As heat is generated when a battery is used, the level of current is also a factor, as well as in which state of charge region the battery is used.

  • 247.
    Jung, Daniel
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    A generalized fault isolability matrix for improved fault diagnosability analysis2016Inngår i: 2016 3RD CONFERENCE ON CONTROL AND FAULT-TOLERANT SYSTEMS (SYSTOL), IEEE , 2016, s. 519-524Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A generalized fault isolability matrix is proposed for quantitative analysis of fault isolability properties. The original fault isolability matrix gives information about which faults that are isolable from each other. However, other relavant isolability properties are not visible which can be important, for example, information regarding alternative fault hypotheses and multiple-fault isolability. The result of the analysis can be presented in the same compact form as the existing fault isolability matrix which makes it simple to visualize. As a case study, a model of an internal combustion engine is analyzed and two different solutions to the test selection problem are compared.

  • 248.
    Jung, Daniel
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Diagnosability performance analysis of models and fault detectors2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Model-based diagnosis compares observations from a system with predictions using a mathematical model to detect and isolate faulty components. Analyzing which faults that can be detected and isolated given the model gives useful information when designing a diagnosis system. This information can be used, for example, to determine which residual generators can be generated or to select a sufficient set of sensors that can be used to detect and isolate the faults. With more information about the system taken into consideration during such an analysis, more accurate estimations can be computed of how good fault detectability and isolability that can be achieved.

    Model uncertainties and measurement noise are the main reasons for reduced fault detection and isolation performance and can make it difficult to design a diagnosis system that fulfills given performance requirements. By taking information about different uncertainties into consideration early in the development process of a diagnosis system, it is possible to predict how good performance can be achieved by a diagnosis system and avoid bad design choices. This thesis deals with quantitative analysis of fault detectability and isolability performance when taking model uncertainties and measurement noise into consideration. The goal is to analyze fault detectability and isolability performance given a mathematical model of the monitored system before a diagnosis system is developed.

    A quantitative measure of fault detectability and isolability performance for a given model, called distinguishability, is proposed based on the Kullback-Leibler divergence. The distinguishability measure answers questions like "How difficult is it to isolate a fault fi from another fault fj?. Different properties of the distinguishability measure are analyzed. It is shown for example, that for linear descriptor models with Gaussian noise, distinguishability gives an upper limit for the fault to noise ratio of any linear residual generator. The proposed measure is used for quantitative analysis of a nonlinear mean value model of gas flows in a heavy-duty diesel engine to analyze how fault diagnosability performance varies for different operating points. It is also used to formulate the sensor selection problem, i.e., to find a cheapest set of available sensors that should be used in a system to achieve required fault diagnosability performance.

    As a case study, quantitative fault diagnosability analysis is used during the design of an engine misfire detection algorithm based on the crankshaft angular velocity measured at the flywheel. Decisions during the development of the misfire detection algorithm are motivated using quantitative analysis of the misfire detectability performance showing, for example, varying detection performance at different operating points and for different cylinders to identify when it is more difficult to detect misfires.

    This thesis presents a framework for quantitative fault detectability and isolability analysis that is a useful tool during the design of a diagnosis system. The different applications show examples of how quantitate analysis can be applied during a design process either as feedback to an engineer or when formulating different design steps as optimization problems to assure that required performance can be achieved.

    Delarbeid
    1. A method for quantitative fault diagnosability analysis of stochastic linear descriptor models
    Åpne denne publikasjonen i ny fane eller vindu >>A method for quantitative fault diagnosability analysis of stochastic linear descriptor models
    2013 (engelsk)Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 49, nr 6, s. 1591-1600Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Analyzing fault diagnosability performance for a given model, before developing a diagnosis algorithm, can be used to answer questions like “How difficult is it to detect a fault fi?” or “How difficult is it to isolate a fault fi from a fault fj?”. The main contributions are the derivation of a measure, distinguishability, and a method for analyzing fault diagnosability performance of discrete-time descriptor models. The method, based on the Kullback–Leibler divergence, utilizes a stochastic characterization of the different fault modes to quantify diagnosability performance. Another contribution is the relation between distinguishability and the fault to noise ratio of residual generators. It is also shown how to design residual generators with maximum fault to noise ratio if the noise is assumed to be i.i.d. Gaussian signals. Finally, the method is applied to a heavy duty diesel engine model to exemplify how to analyze diagnosability performance of non-linear dynamic models.

    sted, utgiver, år, opplag, sider
    Elsevier, 2013
    Emneord
    Fault diagnosability analysis; Fault detection and isolation; Model-based diagnosis
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-89941 (URN)10.1016/j.automatica.2013.02.045 (DOI)000319540500007 ()
    Tilgjengelig fra: 2013-03-11 Laget: 2013-03-11 Sist oppdatert: 2019-09-23bibliografisk kontrollert
    2. Asymptotic behavior of fault diagnosis performance
    Åpne denne publikasjonen i ny fane eller vindu >>Asymptotic behavior of fault diagnosis performance
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Fault detection and fault isolation performance of a model based diagnosis system mainly depends on the level of model uncertainty and the time allowed for detection. The longer time for detection that can be accepted, the more certain detection can be achieved and the main objective of this paper is to show how the window length relates to diagnosis performance. A key result is an explicit expression for asymptotic performance with respect to window length. A key property of the approach is that the model is analyzed directly, which makes the approach independent of detection filter design. It is shown that there exists a linear asymptote as the window length tends to infinity and it is also shown how this linear asymptote can be computed as well as higher order approximations.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-117174 (URN)
    Tilgjengelig fra: 2015-04-21 Laget: 2015-04-21 Sist oppdatert: 2015-04-21bibliografisk kontrollert
    3. Quantitative isolability analysis of different fault modes
    Åpne denne publikasjonen i ny fane eller vindu >>Quantitative isolability analysis of different fault modes
    2015 (engelsk)Inngår i: 9th IFAC Symposium on Fault Detection, Supervision and Safety for Technical Processes SAFEPROCESS 2015 – Paris, 2–4 September 2015: Proceedings / [ed] Didier Maquin, Elsevier, 2015, Vol. 48(21), s. 1275-1282Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    To be able to evaluate quantitative fault diagnosability performance in model-based diagnosis is useful during the design of a diagnosis system. Different fault realizations are more or less likely to occur and the fault diagnosis problem is complicated by model uncertainties and noise. Thus, it is not obvious how to evaluate performance when all of this information is taken into consideration. Four candidates for quantifying fault diagnosability performance between fault modes are discussed. The proposed measure is called expected distinguishability and is based of the previous distinguishability measure and two methods to compute expected distinguishability are presented.

    sted, utgiver, år, opplag, sider
    Elsevier, 2015
    Serie
    IFAC-PapersOnLine, ISSN 2405-8963
    Emneord
    Fault detection and isolation, quantitative diagnosability analysis, Kullback-Leibler divergence
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-117175 (URN)10.1016/j.ifacol.2015.09.701 (DOI)
    Konferanse
    9th IFAC Symposium on Fault Detection, Supervision and Safety for Technical Processes SAFEPROCESS 2015 – Paris, France, 2–4 September 2015
    Merknad

    At the time for thesis presentation publication was in status: Manuscript

    Tilgjengelig fra: 2015-04-21 Laget: 2015-04-21 Sist oppdatert: 2019-09-23bibliografisk kontrollert
    4. Sensor selection for fault diagnosis in uncertain systems
    Åpne denne publikasjonen i ny fane eller vindu >>Sensor selection for fault diagnosis in uncertain systems
    Vise andre…
    2018 (engelsk)Inngår i: International Journal of Control, ISSN 0020-7179, E-ISSN 1366-5820, s. 1-11Artikkel i tidsskrift (Fagfellevurdert) Epub ahead of print
    Abstract [en]

    Finding the cheapest, or smallest, set of sensors such that a specified level of diagnosis performance is maintained is important to decrease cost while controlling performance. Algorithms have been developed to find sets of sensors that make faults detectable and isolable under ideal circumstances. However, due to model uncertainties and measurement noise, different sets of sensors result in different achievable diagnosability performance in practice. In this paper, the sensor selection problem is formulated to ensure that the set of sensors fulfils required performance specifications when model uncertainties and measurement noise are taken into consideration. However, the algorithms for finding the guaranteed global optimal solution are intractable without exhaustive search. To overcome this problem, a greedy stochastic search algorithm is proposed to solve the sensor selection problem. A case study demonstrates the effectiveness of the greedy stochastic search in finding sets close to the global optimum in short computational time.

    sted, utgiver, år, opplag, sider
    Taylor & Francis, 2018
    Emneord
    Fault diagnosis, fault detection and isolation, sensor selection
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-117176 (URN)10.1080/00207179.2018.1484171 (DOI)
    Merknad

    The previous status of this article was Manuscript.

    Tilgjengelig fra: 2015-04-21 Laget: 2015-04-21 Sist oppdatert: 2019-09-23bibliografisk kontrollert
    5. Development of misfire detection algorithm using quantitative FDI performance analysis
    Åpne denne publikasjonen i ny fane eller vindu >>Development of misfire detection algorithm using quantitative FDI performance analysis
    2015 (engelsk)Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 34, s. 49-60Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A model-based misfire detection algorithm is proposed. The algorithm is able to detect misfires and identify the failing cylinder during different conditions, such as cylinder-to-cylinder variations, cold starts, and different engine behavior in different operating points. Also, a method is proposed for automatic tuning of the algorithm based on training data. The misfire detection algorithm is evaluated using data from several vehicles on the road and the results show that a low misclassification rate is achieved even during difficult conditions. (C) 2014 Elsevier Ltd. All rights reserved.

    sted, utgiver, år, opplag, sider
    Elsevier, 2015
    Emneord
    Misfire detection; Fault diagnosis; Fault detection and isolation; Kullback-Leibler divergence; Pattern recognition
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-114011 (URN)10.1016/j.conengprac.2014.10.001 (DOI)000347599500005 ()
    Merknad

    Funding Agencies|Volvo Car Corporation; Swedish Research Council within the Linnaeus Center CADICS

    Tilgjengelig fra: 2015-02-06 Laget: 2015-02-05 Sist oppdatert: 2019-09-23
    6. A flywheel error compensation algorithm for engine misfire detection
    Åpne denne publikasjonen i ny fane eller vindu >>A flywheel error compensation algorithm for engine misfire detection
    2016 (engelsk)Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 47, s. 37-47Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A commonly used signal for engine misfire detection is the crankshaft angular velocity measured at the flywheel. However, flywheel manufacturing errors result in vehicle-to-vehicle variations in the measurements and have a negative impact on the misfire detection performance, where the negative impact is quantified for a number of vehicles. A misfire detection algorithm is proposed with flywheel error adaptation in order to increase robustness and reduce the number of mis-classifications. Since the available computational power is limited in a vehicle, a filter with low computational load, a Constant Gain Extended Kalman Filter, is proposed to estimate the flywheel errors. Evaluations using measurements from vehicles on the road show that the number of mis-classifications is significantly reduced when taking the estimated flywheel errors into consideration.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-117177 (URN)10.1016/j.conengprac.2015.12.009 (DOI)000370091900004 ()
    Merknad

    Funding agencies:The work is partially supported by the Swedish Research Council within the Linnaeus Center CADICS.

    Vid tiden för disputation förelåg publikationen endast som manuskript

    Tilgjengelig fra: 2015-04-21 Laget: 2015-04-21 Sist oppdatert: 2019-09-23bibliografisk kontrollert
  • 249.
    Jung, Daniel
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Dong, Yi
    Institute for Software Integrated Systems, Vanderbilt University, Nashville, USA.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Krysander, Mattias
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska högskolan.
    Biswas, Gautam
    Institute for Software Integrated Systems, Vanderbilt University, Nashville, USA.
    Sensor selection for fault diagnosis in uncertain systems2018Inngår i: International Journal of Control, ISSN 0020-7179, E-ISSN 1366-5820, s. 1-11Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Finding the cheapest, or smallest, set of sensors such that a specified level of diagnosis performance is maintained is important to decrease cost while controlling performance. Algorithms have been developed to find sets of sensors that make faults detectable and isolable under ideal circumstances. However, due to model uncertainties and measurement noise, different sets of sensors result in different achievable diagnosability performance in practice. In this paper, the sensor selection problem is formulated to ensure that the set of sensors fulfils required performance specifications when model uncertainties and measurement noise are taken into consideration. However, the algorithms for finding the guaranteed global optimal solution are intractable without exhaustive search. To overcome this problem, a greedy stochastic search algorithm is proposed to solve the sensor selection problem. A case study demonstrates the effectiveness of the greedy stochastic search in finding sets close to the global optimum in short computational time.

  • 250.
    Jung, Daniel
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Krysander, Mattias
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska högskolan.
    Development of misfire detection algorithm using quantitative FDI performance analysis2015Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 34, s. 49-60Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A model-based misfire detection algorithm is proposed. The algorithm is able to detect misfires and identify the failing cylinder during different conditions, such as cylinder-to-cylinder variations, cold starts, and different engine behavior in different operating points. Also, a method is proposed for automatic tuning of the algorithm based on training data. The misfire detection algorithm is evaluated using data from several vehicles on the road and the results show that a low misclassification rate is achieved even during difficult conditions. (C) 2014 Elsevier Ltd. All rights reserved.

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