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  • 51.
    Lundahl, Kristoffer
    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.
    Vehicle dynamics platform, experiments, and modeling aiming at critical maneuver handling2013Rapport (Övrigt vetenskapligt)
    Abstract [en]

    For future advanced active safety systems, in road-vehicle applications, there will arise possibilities for enhanced vehicle control systems, due to refinements in, e.g., situation awareness systems. To fully utilize this, more extensive knowledge is required regarding the characteristics and dynamics of vehicle models employed in these systems. Motivated by this, an evaluative study for the lateral dynamics is performed, considering vehicle models of more simple structure. For this purpose, a platform for vehicle dynamics studies has been developed. Experimental data, gathered with this testbed, is then used for model parametrization, succeeded by evaluation for an evasive maneuver. The considered model configurations are based on the single-track model, with different additional attributes, such as tire-force saturation, tire-force lag, and roll dynamics. The results indicate that even a basic model, such as the single-track with tire-force saturation, can describe the lateral dynamics surprisingly well for this critical maneuver.

  • 52.
    Nielsen, Lars
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    An Ion-Sense Engine-Fine-Tuner1998Ingår i: IEEE Control Systems, ISSN 1066-033X, Vol. 18, nr 5, s. 43-52Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    IEEE Control Systems: Special Issue on Powertrain Control, October 1998 Combustion engines are highly engineered complex system. Many variables like engine speed and load are measured, but there are many other variables influencing engine performance that are not measured. One such variable that strongly influences efficiency and power is air humidity. Even with such varying unmeasured variables, it is well known that a skilled human mechanic can diagnose and fine tune a car according to the environment and circumstances at a certain place and day. Inspired by these skills in combination with the development of computing power, it is possible to think of virtual engine-doctors and virtual engine-fine-tuners. Here an ion-sense engine-fine-tuner has been developed based on spark advance feed-back control using ionization current interpretation. It is shown, as a main result, that it can control the engine back to its optimal operation even when subjected to humidity in the intake air.

  • 53.
    Nielsen, Lars
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Nyberg, Mattias
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Bäckström, Christer
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Henriksson, Anders
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Klein, Inger
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Gustafsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Gunnarsson, Svante
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Issues in Diagnosis, Supervision, and Safety1996Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Issues concerning diagnosis, supervision and saftey are found in many technologically advanced products. There is now a trend to extend the functionality of diagnosis and supervision systems to handle more advanced situations. This report collects some of the initiatives taking place in research and some of the developments taking place in the industry.

  • 54.
    Nilsson, Ylva
    et al.
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen , Lars
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Weak knock characterization and detection for knock control2009Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering, ISSN 0954-4070, E-ISSN 2041-2991, Vol. 223, nr D1, s. 107-129Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Knock is a fundamental phenomenon in combustion engines, and knock control is central in any engine management system. Better understanding of knock, and weak knock in particular, is considered from two main aspects: knock detection and knock characterization. The aim of knock detectors is both to detect knock and to estimate the crank angle at knock onset. Focusing on weaker knock than before, it is shown that knock detectors and algorithms have to take into account other characteristics of knock traces than the standard model. It is shown that the best-performing knock detector of those investigated is one that supervises changes in signal variance, except for low signal-to-noise ratios where it is advantageous to use also the oscillation frequency. Regarding characterization, an important result is that in a wide range of intensities there is an almost linear dependence between the logarithmic normalized knock energy and the rate of cycles with knock. This means for example that a knock controller can use feedback on the rate of cycles with knock instead of knock intensity and vice versa; both can in combination with better detection provide possibilities for smoother and more anticipatory control schemes.

  • 55.
    Nyberg, Mattias
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    A Universal Chow-Willsky Scheme and Detectability Criteria2000Ingår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 45, nr 1, s. 152-156Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An important issue in diagnosis research is design methods for residual generation. One method is the Chow-Willsky scheme, which is here extended such as it becomes universal in the sense that, for both discrete and continuous linear systems, it is shown to be able to generate all possible parity functions. It is shown that previous extensions to the Chow-Willsky scheme are not universal, which happens when there are dynamics controllable from faults but not from the inputs or disturbances. Also included are two new conditions on the process for fault detectability and strong fault detectability.

  • 56.
    Nyberg, Mattias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik.
    A universal Chow-Willsky scheme and detectability criteria2000Ingår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 45, nr 1, s. 152-156Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An important issue in diagnosis research is design methods for residual generation. One method is the Chow-Willsky scheme. Here, the Chow-Willsky scheme is extended as it becomes universal in the sense that, for both discrete and continuous linear systems, it Is shown to be able to generate all possible parity functions. This result means it can also be used to design all possible residual generators. It is shown previous extensions to the Chow-Willsky scheme are not universal, which is the case when dynamics controllable from fault exist, but not from the inputs or disturbances. Also included here are two new conditions on the process for fault detectability and strong fault detectability. A general condition for strong fault detectability has not been presented elsewhere.

  • 57.
    Nyberg, Mattias
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Model Based Diagnosis for the Air Intake System of the SI-Engine1998Ingår i: SAE technical paper series, ISSN 0148-7191, Vol. 106, s. 9-20Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Because of legislative regulations like OBDII, on-board diagnosis has gained much interest lately. A model based approach is suggested for the diagnosis of the air intake system of an SI-engine. Important research issues are modeling concepts, residual generation and evaluation, overall performance, and limiting factors. The diagnosis system is based on a non-linear semi-physical model and uses a combination of different residual generation methods. It is capable of detecting and isolating faults in the throttle actuator, throttle sensor, air mass flow sensor and manifold pressure sensor. The scheme is experimentally validated on a real production engine.

  • 58.
    Nyberg, Mattias
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Parity Functions as Universal Residual Generators and Tool for Fault Detectability Analysis1997Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Chow-Willsky scheme is a design method for residual generation. Here an extension to the Chow-Willsky scheme, called the ULPE scheme, is presented. The ULPE scheme is shown to be able to generate all possible residual generators for both discrete and continuous linear systems. It is also shown that previous extensions to the Chow-Willsky scheme do not have this capability. Two new straightforward conditions on the process for fault detectability and strong fault detectability are presented. A general condition for strong fault detectability has not been presented elsewhere. It is shown that fault detectability and strong fault detectability can be seen as system properties rather than properties of the residual generator.

  • 59.
    Nyberg, Peter
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Driving Cycle Adaption and Design Based on Mean Tractive Force2013Ingår i: Proceedings of the 7th IFAC Symposium on Advances in Automotive Control, The International Federation of Automatic Contro, Elsevier, 2013, Vol. 46, nr 21, s. 689-694Konferensbidrag (Refereegranskat)
    Abstract [en]

    Driving cycles are used for certification, for comparison of vehicles, and to an increasing extent as an engineering tool in vehicle design. A situation with only a few fixed driving cycles to use would then lead to the risk that a test or design would be tailored to details in the driving cycle instead of being representative. Due to this, and due to the increased use in the development process, there is now a strong need for methods to achieve representative driving cycles that in a wide sense are similar but not the same. To approach this problem area, we define equivalence between driving cycles based on mean tractive force, and develop algorithms and methods for equivalence-modification and equivalence-transformation of driving cycles. There are a number of applications for these methods but one example that is demonstrated is to transform the well-known FTP75 into an equivalent NEDC, and the other way around, to transform the NEDC into an equivalent FTP75.

  • 60.
    Nyberg, Peter
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan.
    Driving Cycle Adaption and Design Based on Mean Tractive ForceManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Driving cycles are used for certification, for comparison of vehicles, and to an increasing extent as an engineering tool in vehicle design. A situation with only a few fixed driving cycles to use would then lead to the risk that a test or design would be tailored to details in the driving cycle instead of being representative. Due to this, and due to the increased use in the development process, there is now a strong need for methods to achieve representative driving cycles that in a wide sense are similar but not the same. To approa ch this problem area, we define equivalence between driving cycles based on mean tractive force, and develop algorithms and methods for equivalence-modification and equivalence-transformation of driving cycles. There are a number of applications for these methods but one example that is demonstrated is to transform the well-known FTP75 into an equivalent NEDC, and the other way around, to transform the NEDC into an equivalent FTP75.

  • 61.
    Nyberg, Peter
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Driving Cycle Equivalence and Transformation2017Ingår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 66, nr 3, s. 1963-1974Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is a current strong trend where driving cycles are used extensively in vehicle design, especially for calibration and tuning of all powertrain systems for control and diagnosis. In such situations it is essential to capture real driving, and therefore using only a few driving cycles would lead to the risk that a test or a design would be tailored to details in a specific driving cycle. Consequently there are now widespread activities using techniques from statistics, big data and mission modeling to address these issues. For all such methods there is an important final step to calibrate a representative cycle to adhere to fair propulsion requirements on the driven wheels over a cycle. For this a general methodology has been developed, applicable to a wide range of problems involving driving cycle transformations. It is based on a definition of equivalence for driving cycles that loosely speaking defines being similar without being the same. Based on this, a set of algorithms are developed to transform a given driving cycle into an equivalent one, or into a cycle with given equivalence measure. The transformations are effectively handled as a nonlinear program that is solved using general purpose optimization techniques. The proposed method is general and a wide range of constraints can be used.

  • 62.
    Nyberg, Peter
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Generation of Equivalent Driving Cycles Using Markov Chains and Mean Tractive Force Components2014Ingår i: Proceedings of the 19th World Congress, The International Federation of Automatic Control, Elsevier, 2014, Vol. 47, nr 3, s. 8787-8792Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the automotive industry driving cycles have been used to evaluate vehicles in different perspectives. If a vehicle manufacturer focuses only on a fixed driving cycle there is a risk that controllers of the vehicle are optimized for a certain driving cycle and hence are sub-optimal solutions to real-world driving. To deal with this issue, it is beneficial to have a method for generating more driving cycles that in some sense are equivalent but not identical. The idea here is that these generated driving cycles have the same vehicle excitation in the mean tractive force, MTF. Using the individual force components of the MTF in the generation of driving cycles with Markov chains makes it possible to generate equivalent driving cycles that have the same vehicle excitation from real-world driving data. This is motivated since the fuel consumption estimation is more accurate when the MTF components are considered. The result is a new method that combines the generation of driving cycles using real-world driving cycles with the concept of equivalent driving cycles, and the results are promising.

  • 63.
    Nyberg, Peter
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Using Real-World Driving Databases to Generate Driving Cycles with Equivalence Properties2016Ingår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 65, nr 6, s. 4095-4105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Due to the increasing complexity of vehicle design, understanding driver behavior and driving patterns is becoming increasingly more important. Therefore, a large amount of test driving is performed, which together with recordings of normal driving, results in large databases of recorded drives. A fundamental question is how to make best use of these data to devise driving cycles suitable in the development process of vehicles. One way is to generate driving cycles that are representative for the data or for a suitable subset of the data, e.g., regarding geographical location, driving distance, speed range, or many other possible selection variables. Further, to make a fair comparison on two such driving cycles possible, another fundamental requirement is that they should have similar excitation of the vehicle. A key contribution here is an algorithm that combines the two given objectives. A formulation with Markov processes is used to obtain a condensed and effective characterization of the database and to generate candidate driving cycles (CDCs). In addition to that is a method transforming a candidate to an equivalent driving cycle (EqDC) with desired excitation. The method is a general approach but is here based on the components of the mean tractive force (MTF), and this is motivated by a hardware-in-the-loop experiment showing the strong relevance of these MTF components regarding fuel consumption. The result is a new method that combines the generation of driving cycles using real-world driving cycles with the concept of EqDCs.

  • 64.
    Olofsson, Björn
    et al.
    Department of Automatic Control, Lund University, Lund, Sweden.
    Lundahl, Kristoffer
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Berntorp, Karl
    Department of Automatic Control, Lund University, Lund, Sweden.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    An Investigation of Optimal Vehicle Maneuvers for Different Road Conditions2013Ingår i: IFAC Proceedings Volumes, Volume 46, Issue 21, International Federation of Automatic Control , 2013, Vol. 46, s. 66-71Konferensbidrag (Refereegranskat)
    Abstract [en]

    We investigate optimal maneuvers for road-vehicles on different surfaces such as asphalt, snow, and ice. The study is motivated by the desire to find control strategies for improved future vehicle safety and driver assistance technologies. Based on earlier presented measurements for tire-force characteristics, we develop tire models corresponding to different road conditions, and determine the time-optimal maneuver in a hairpin turn for each of these. The obtained results are discussed and compared for the different road characteristics. Our main findings are that there are fundamental differences in the control strategies on the considered surfaces, and that these differences can be captured with the adopted modeling approach. Moreover, the path of the vehicle center-of-mass was found to be similar for the different cases. We believe that these findings imply that there are observed vehicle behaviors in the results, which can be utilized for developing the vehicle safety systems of tomorrow.

  • 65.
    Pettersson, M.
    et al.
    SCANIA AB, Södertälje SE-151 87, Sweden.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik.
    Diesel engine speed control with handling of driveline resonances2003Ingår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 11, nr 3, s. 319-328Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A vehicular driveline transfer engine torque to the wheels. Resonances in the elastic parts of the driveline are important to handle when control of the engine and the transmission is optimized. Traditional diesel engine speed control maintains a well-damped engine speed set by the driver. However, the resonance modes of the driveline are easily excited by accelerator-position changes or by road disturbances. A speed-control strategy is proposed that includes the behavior of the driveline, and reduces driveline resonaces and vehicle shuffle by engine control. Implementation shows significant reduction, also when facing nonlinear torque limitations from maximum torque and diesel smoke delimiters. © 2002 Elsevier Science Ltd. All rights reserved.

  • 66.
    Pettersson, M.
    et al.
    Scania, Engine Development, S-151 87 Södertälje, Sweden.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik.
    Gear shifting by engine control2000Ingår i: IEEE Transactions on Control Systems Technology, ISSN 1063-6536, E-ISSN 1558-0865, Vol. 8, nr 3, s. 495-507Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    By using engine control during the gear shift, a manual transmission can be automated without using the clutch during the shift event. It is then important to minimize the total time needed for a gear shift, but when doing so driveline resonances may be excited. This in turn may lead to problems with disengaging the old gear and synchronizing speeds for engaging the new gear. Internal driveline torque control is a novel idea for handling resonances and increasing shift quality. By estimating the transmitted torque and controlling it to zero by engine control, the gear can systematically be disengaged with minimized driver disturbances and faster speed synchronization. Field trials show fast shifts to neutral gear, despite disturbances and driveline oscillations at the start of the gear shift. The control scheme is simple and robust against variations among different gears. Furthermore, damping of driveline resonances can be obtained with an observer in combination with a proportional integral derivative feedback structure, despite the higher order driveline system.

  • 67.
    Pettersson, Magnus
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Driveline Modeling and RQV Control with Active Damping of Vehicle Shuffle1997Ingår i: Electronic Engine Controls 1997 (SP-1236), Society of Automotive Engineers, Inc. , 1997, artikel-id 970536Konferensbidrag (Refereegranskat)
    Abstract [en]

    Driveline control is a challenging area. With traditional fuel metering systems, driveline oscillations may follow load disturbances or changes in accelerator position. This problem, emphasized with increased engine power, together with overall increased performance demands leads to a need for more advanced driveline control.

    The main contribution of the paper is a strategy for fuel metering with active handling of driveline resonances, reducing wheel speed oscillations. Experiments and modeling using a 6x2 heavy truck lead to a linear model capturing the significant torsional resonances in the driveline. A formulation tractable for analysis, design, and implementation is developed. Field trials show that the engine can be controlled to reduce low frequency driveline oscillations, also when facing engine torque restrictions due to diesel smoke reduction. The system thus improves both performance and driveability.

  • 68.
    Pettersson, Magnus
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Sensor Placement for Driveline Control1995Ingår i: Proceedings of IFAC Advances in Automotive Control, 1995, Vol. 28, s. 169-174Konferensbidrag (Refereegranskat)
    Abstract [en]

    Vehicular drivelines can be instrumented with sensors in different locations. Control and damping of torsional oscillations will therefore lead to, depending on sensor location, control problems where the control objective signal is not the same as the measured output signal. It turns out that it is convenient to work with a modified complementary sensitivity function, being modified with a dynamic output ratio. The specific characteristics of a driveline model is analyzed using these concepts, and the consequences for design of feedback controllers are discussed.

  • 69.
    Sundström, Christofer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    A New Electric Machine Model and its Relevance for Vehicle Level Diagnosis2015Ingår i: International Journal of Modelling, Identification and Control, ISSN 1746-6172, Vol. 24, nr 1, s. 1-9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With the electrification of society, especially transportation, the control and supervision of electrical machines become more and more important due to its bearing on energy, environment, and safety. To optimise performance in control and supervision, appropriate modelling is crucial, and this regards both the ability to capture reality and the computational complexity to be useful in real-time. Here, a new low complexity model of the electric machine is proposed and developed. The new model treats the machine constants in a different way compared to a previous standard model, which results in a different expression for power losses. It is shown that this increases model expressiveness so when adapted to real data the result is significantly better. The significance of this modelling improvement is demonstrated using a task in vehicle diagnosis where it is shown that the separation between the non-faulty and faulty cases is better and the resulting performance is improved.

  • 70.
    Sundström, Christofer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    A Platform for Overall Monitoring and Diagnosis for Hybrid Vehicles2010Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Compared with conventional vehicles, designing hybrid electric vehicles includes new features, such as energy management and monitoring of the electrical components. To be able to investigate such issues a simulation platform of a hybrid vehicle, driver, and diagnosis system is developed based on the CAPSim model library. The simulation platform is component based, and is able to handle different powertrain configurations. In this investigation a parallel hybrid is modeled and parameterized to represent a long haulage truck. To be able to easily change a model of a component in the vehicle model, every model of a specific component use the same sets of input and output signals. The vehicle model is based on dynamic equations and in general simple models of the components, since the interplay of the components is of major interest in this investigation. Three model based diagnosis systems are developed and implemented in the platform with a twofolded purpose. The first purpose is to demonstrate the feasibility of the platform. The second purpose is to investigate issues when designing diagnosis systems on vehicle level of a hybrid vehicle powertrain. New features, for example mode switches in the system and a freedom in choosing operating points of the components via the energy management, affect the diagnosis system. The influence of these issues on the performance of the diagnosis system is investigated by design and implementation of three diagnosis systems on a vehicle level. The diagnosis systems are based on three sensor configurations. Two of these consist of several sensors and one system uses few sensors. In one of the systems using information from several sensors, the sensors are placed close to the components that are to be monitored, while the sensors in the other system is based on a different sensor configuration. All three diagnosis systems detect specific faults, here specifically faults in the electrical components in a hybrid vehicle powertrain, but the methodology is generic. It is shown that there is a connection between the design of the energy management and the three diagnosis systems, and that this interplay is of special relevance when models of components are valid only in some operating modes. The diagnosis system based on few sensors is more complex and includes a larger part of the vehicle model than the system based on several sensors placed close to the components to be monitored.

  • 71.
    Sundström, Christofer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Diagnostic Method Combining Map and Fault Models Applied on a Hybrid Electric Vehicle2014Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    A common situation in the automotive industry is that map based models are available. In general these models accurately describe the fault free system, and are therefore suited for fault detectability in a diagnosis system. However, one drawback using such a model is that fault isolation then requires that measurements of the faulty system is done, which is costly. Another approach is to use a model of the system where the faults are explicitly included. To directly achieve good diagnostic performance such a model needs to be accurate, which also is costly. Therefore, in the new approach taken here, two models are used in combination to achieve both good fault detectability and isolability in a diagnosis system; one is a map based model, and one is describing how the faults affect the system. The approach is exemplified by designing a diagnosis system monitoring the power electronics and the electric machine in a hybrid electric vehicle. In an extensive simulation study it is shown that the approach works well and is a promising path to achieve both good fault detectability and isolability performance, without the need for neither measurements of a faulty system nor detailed physical modeling. In the designed diagnosis system all faults are fully isolated, and the size of the faults are accurately estimated.

  • 72.
    Sundström, Christofer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Diagnostic Method Combining the Lookup Tables and Fault Models Applied on a Hybrid Electric Vehicle2016Ingår i: IEEE Transactions on Control Systems Technology, ISSN 1063-6536, E-ISSN 1558-0865, Vol. 24, nr 3, s. 1109-1117Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A common situation in industry is to store measurements for different operating points in the lookup tables, often called maps. They are used in many tasks, e.g., in control and estimation, and therefore considerable investments in engineering time are spent in measuring them which usually make them accurate descriptions of the fault-free system. They are thus well suited for fault detection, but, however, such a model cannot give fault isolation since only the fault free behavior is modeled. One way to handle this situation would be also to map all fault cases but that would require measurements for all faulty cases, which would be costly if at all possible. Instead, the main contribution here is a method to combine the lookup model with analytical fault models. This makes good use of all modeling efforts of the lookup model for the fault-free case, and combines it with fault models with reasonable modeling and calibration efforts, thus decreasing the engineering effort in the diagnosis design. The approach is exemplified by designing a diagnosis system monitoring the power electronics and the electric machine in a hybrid electric vehicle. An extensive simulation study clearly shows that the approach achieves both good fault detectability and isolability performance. A main point is that this is achieved without the need for neither measurements of a faulty system nor detailed physical modeling, thus saving considerable amounts of development time.

  • 73.
    Sundström, Christofer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Fault Monitoring of the Electric Machine in a Hybrid Vehicle2013Ingår i: Proceedings of the 7th IFAC Symposium on Advances in Automotive Control, The International Federation of Automatic Control, Elsevier, 2013, Vol. 46, nr 21, s. 548-553Konferensbidrag (Refereegranskat)
    Abstract [en]

    A diagnosis system for the electric machine and the power electronics in a hybrid electric vehicle is designed, where the diagnosis system uses a map based model of the system to be monitored. Such a model gives an accurate description of the fault free system, and is therefore suited for fault detectability. However, one drawback using such a model for diagnosis is that fault isolation often requires that the model, in addition to the fault free case, also describes the faulty system, and thereby measurements of the faulty system are needed, which is costly. Another approach is to use a model including physical parameters of interest in the system to be monitored, to also describe the faults’ impact on the system. To achieve good diagnostic performance such a model needs to be accurate, which also is costly. Therefore, in the new approach taken here, two models for the system are used in combination to achieve good fault detectability and isolability; one is a map based model, and one is describing the faults of the system. It is shown that the approach works well and is a promising path to achieve both good fault detectability and isolability performance, without the need for neither measurements of a faulty system nor detailed physical modeling. In a simulation study evaluating the designed diagnosis system all faults are isolated and also accurately estimated.

  • 74.
    Sundström, Christofer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Overall Monitoring and Diagnosis for Hybrid Vehicle Powertrains2010Ingår i: Proceedings of the 6th IFAC Symposium on Advances in Automotive Control,  July 12-14, Munich, Germany / [ed] Ansgar Trächtler and Dirk Abel, 2010, s. 93-98Konferensbidrag (Refereegranskat)
    Abstract [en]

    Designing diagnosis systems for hybrid vehicles include new features compared to conventional vehicles, e.g. mode switches in the system. The influence of this on the performance of the diagnosis system is investigated by design and implementation of diagnosis systems on vehicle level. The diagnosis systems are based on two sensor configurations, one consisting of many sensors and one of few sensors. The diagnosis systems detect specific faults, here specifically faults in the electrical components in a hybrid vehicle driveline, but the methodology is generic. There is a connection between the design of the energy management and the diagnosis system, and this interplay is of special relevance when models of components are valid only in some operating modes. In the systems implemented, the diagnosis system based on few sensors is more complex and includes a larger part of the vehicle model than the system based on more sensors.

  • 75.
    Sundström, Christofer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Residual Generator Selection for Fault Diagnosis of Hybrid Vehicle Powertrains2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    The performance of a model based diagnosis system is affected by the selection of consistency relation in a set of equations with analytical redundancy in a non-linear system. To investigate aspects due to this, two diagnosis systems of a parallel hybrid truck are designed, and both static and dynamic issues are considered. A simplified vehicle model is used to exemplify how a unique expression for the residual generator can be found for one selection of consistency relation, but not for others, using the same set of equations. A simulation study using the entire vehicle model is made to investigate how the performance in the diagnosis system is affected when dynamic equations are either differentiated or integrated. The diagnosis systems are designed using structural analysis in combination with the algebraic expressions. One key result is that it is not trivial to find a computational order by hand that fulfills the predefined conditions on the computational sequence, and therefore systematic methods are valuable.

  • 76.
    Sundström, Christofer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Selecting and Utilizing Sequential Residual Generators in FDI Applied to Hybrid Vehicles2014Ingår i: IEEE TRANSACTIONS ON SYSTEMS MAN CYBERNETICS-SYSTEMS, ISSN 2168-2216, Vol. 44, nr 2, s. 172-185Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to obtain a realistic model of a complex system, thousands of possible residual generators need to be used for diagnosis. Based on engineering insights of the system to be monitored, certain algebraic and dynamic properties of the residual generators may be preferred, and therefore, a method for finding sequential residual generators is developed that accounts for these properties of the residual generator candidates. It is shown that only a small fraction of all residual generator candidates fulfill fundamental requirements, and thereby, proves the value of systematic methods. Furthermore, methods are devised for utilization of the residual generators, such as initialization of dynamic residual generators. A proposed method, considering the fault excitation in the residuals using the internal form of the residuals, significantly increases the diagnosis performance. A hybrid electric vehicle is used in a simulation study for demonstration, but the methods used are general in character and provides a basis when designing diagnosis systems for other complex systems.

  • 77.
    Wahlström, Johan
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Controller Tuning based on Transient Selection and Optimization for a Diesel Engine with EGR and VGT2008Ingår i: Electronic Engine Controls, SAE World Congress & Exhibition, April, Detroit, MI, USA: SAE Technical paper series SP-2159, 2008-01-0985, SAE International , 2008, s. 2008-01-0985-Konferensbidrag (Refereegranskat)
    Abstract [en]

    In modern Diesel engines Exhaust Gas Recirculation (EGR) and Variable Geometry Turbochargers (VGT) have been introduced to meet the new emission requirements. A control structure that coordinates and handles emission limits and low fuel consumption has been developed. This controller has a set of PID controllers with parameters that need to be tuned. To be able to achieve good performance, an optimization based tuning method is developed and tested. In the optimization the control objectives are captured by a cost function. To aid the tuning a systematic method has been developed for selecting representative and significant transients that excite different modes in the controller. The performance is evaluated on the European Transient Cycle. It is demonstrated how weighting factors in the cost function influence control behavior, and that the proposed tuning method gives a significant improvement in control performance compared to standardized tuning methods for PID controllers. Further, the proposed tuning method and the control structure are applied and validated on an engine in a test cell, where it is demonstrated that the control structure achieves all stated control objectives.

  • 78.
    Wahlström, Johan
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    EGR-VGT Control and Tuning for Pumping Work Minimization and Emission Control2010Ingår i: IEEE Transactions on Control Systems Technology, ISSN 1063-6536, E-ISSN 1558-0865, Vol. 18, nr 4, s. 993-1003Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A control structure is proposed and investigated for coordinatedcontrol of EGR valve and VGT position in heavy duty diesel engines.Main control goals are to fulfill the legislated emission levels, toreduce the fuel consumption, and to fulfill safe operation of theturbocharger. These goals are achieved through regulation ofnormalized oxygen/fuel ratio and intake manifoldEGR-fraction. These are chosen both as main performance variables andfeedback variables since they contain information about when it ispossible to decrease the fuel consumption by minimizing the pumpingwork. Based on this a novel and simple pumping work minimizationstrategy is developed.The proposed performance variables are also strongly coupled to theemissions which makes it easier to adjust set-points, e.g. dependingon measured emissions during an emission calibration process, since itis more straightforward than control of manifold pressure and air massflow. Further, internally the controller is structured to handle thedifferent control objectives. Controller tuning is important forperformance but can be time consuming and to meet this end a method isdeveloped where the controller objectives are captured in a costfunction, which makes automatic tuning possible even though objectivesare conflicting. Performance trade-offs are necessary and areillustrated on the European Transient Cycle. The proposed controlleris validated in an engine test cell, where it is experimentallydemonstrated that the controller achieves all the control objectivesand that the current production controller has at least 26% higherpumping losses compared to the proposed controller.

  • 79.
    Wahlström, Johan
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    System analysis of a Diesel Engine with VGT and EGR2009Rapport (Övrigt vetenskapligt)
    Abstract [en]

    A system analysis of a diesel engine with VGT and EGR is performed in order to obtain insight into a VGT and EGR control problem where the goal is to control the performance variables oxygen fuel ratio and EGR-fraction using the VGT actuator and the EGR actuator. Step responses over the entire operating region show that the channels VGT to oxygen fuel ratio, EGR-valve to oxygen fuel ratio, and VGT to EGR-fraction have non-minimum phase behaviors and sign reversals. The fundamental physical explanation of these system properties is that the system consists of two dynamic effects that interact: a fast pressure dynamics in the manifolds and a slow turbocharger dynamics. It is shown that the engine frequently operates in operating points where the non-minimum phase behaviors and sign reversals occur for the channels VGT to oxygen fuel ratio and VGT to EGR-fraction, and consequently, it is important to consider these properties in a control design. Further, an analysis of zeros for linearized multiple input multiple output models of the engine shows that they are non-minimum phase over the complete operating region. A mapping of the performance variables oxygen fuel ratio and EGR-fraction and the relative gain array show that the system from EGR-valve and VGT to oxygen fuel ratio and EGR-fraction is strongly coupled in a large operating region. It is also illustrated that the pumping losses decrease with increasing EGR-valve and VGT opening for almost the complete operating region.

  • 80.
    Wahlström, Johan
    et al.
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Pettersson, Magnus
    Engine Software and OBD Scania.
    PID controllers and their tuning for EGR and VGT control in diesel engines2005Ingår i: Preprints of the 16th IFAC World Congress, Prague, Czech Republic: Elsevier , 2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    A PID structure is proposed and investigated for coordinated control of EGR-valve and VGT-position in heavy duty diesel engines. Control goals are to fulfill the legislated emission levels and safe operations of the engine and the turbocharger. These goals are achieved through regulation of the following performance variables: normalized air/fuel ratio lambda, intake manifold EGR-fraction as well as turbocharger speed. A systematic tuning strategy for the PID controllers is also developed and the tuning rules and their performance is successfully illustrated on a demanding part of the European Transient Cycle. Further, it is demonstrated that the VGT-position to turbocharger speed loop does benefit from a derivative part in order to predict high turbocharger speeds. This is due to the large time constant in the corresponding open-loop transfer function.

  • 81.
    Åslund, Jan
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Biteus, Jonas
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Frisk, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Krysander, Mattias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    A systematic inclusion of diagnosis performance in fault tree analysis2005Ingår i: IFAC World Congress,2005, Prague, Czech Republic: IFAC , 2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    Safety is of major concern in many applications such as in automotive systems and aerospace. In these applications it is standard to use fault trees, and a natural question in many modern systems that include sub-systems like diagnosis, fault tolerant control and autonomous functions, is how to include the performance of these algorithms in a fault tree analysis for safety. Many possibilities exist but here a systematic way is proposed. It is shown both how safety can be analyzed and how the interplay between algorithm design in terms of missed detection rate and false alarm rate is included in the fault tree analysis. Examples illustrate analysis of diagnosis system requirement specification and algorithm tuning.

  • 82.
    Åslund, Jan
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Biteus, Jonas
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Frisk, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Krysander, Mattias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Safety analysis of autonomous systems by extended fault tree analysis2007Ingår i: International journal of adaptive control and signal processing (Print), ISSN 0890-6327, E-ISSN 1099-1115, Vol. 21, nr 2-3, s. 287-298Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Safety is of major concern in many autonomous functions in automotive systems and aerospace. In these application areas, it is standard to use fault trees, and a natural question in many modern systems that include sub-systems like diagnosis, fault-tolerant control, and autonomous functions is how to include the performance of these algorithms in a fault tree analysis for safety. Many possibilities exist but here a systematic way is proposed. It is shown both how safety can be analysed and how the interplay between algorithm design in terms of missed detection rate and false alarm rate is included in the fault tree analysis. Examples illustrate analysis of diagnosis system requirement specification and algorithm tuning. Copyright © 2006 John Wiley & Sons, Ltd.

  • 83.
    Öberg, Per
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nyberg, Peter
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan.
    A New Chassis Dynamometer Laboratory for Vehicle Research2013Ingår i: SAE International Journal of Passenger Cars - Electronic and Electrical Systems, ISSN 1946-4614, E-ISSN 1946-4622, Vol. 6, nr 1, s. 152-161Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In recent years the need for testing, calibration and certification of automotive components and powertrains have increased, partly due to the development of new hybrid concepts. At the same time, the development within electrical drives enables more versatile chassis dynamometer setups with better accuracy at a reduced cost. We are developing a new chassis dynamometer laboratory for vehicle research, aiming at extending a recently commercially available dynamometer, building a new laboratory around it, and applying the resulting facility to some new challenging vehicle research problems. The projects are enabled on one hand by collaboration with the dynamometer manufacturer, and on the other hand on collaboration with automotive industry allowing access to relevant internal information and equipment. The test modes of the chassis dynamometer are under development in a joint collaboration with the manufacturer. The laboratory has been operational since September 2011 and has already been used for NVH-analysis for a tire pressure indication application, chassis dynamometer road force co-simulation with a moving base simulator, co-surge modeling and control for a 6-cylinder bi-turbo engine, and traditional engine mapping. We are also looking at projects with focus on look-ahead control, as well as clutch and transmission modeling and control, and driving cycle related research.

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