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Stability Control of Electric Vehicles with In-Wheel Motors

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Stability Control of Electric Vehicles with In-Wheel Motors Stability Control of Electric Vehicles with In-wheel Motors by Kiumars Jalali A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Doctor of Philosophy in Mechanical Engineering Waterloo, Ontario, Canada, 2010 © Kiumars Jalali 2010 I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. Kiumars Jalali ii Abstract Recently, mostly due to global warming concerns and high oil prices, electric vehicles have attracted a great deal of interest as an elegant solution to environmental and energy problems. In addition to the fact that electric vehicles have no tailpipe emissions and are more efficient than internal combustion engine vehicles, they represent more versatile platforms on which to apply advanced motion control techniques, since motor torque and speed can be generated and controlled quickly and precisely. The chassis control systems developed today are distinguished by the way the individual subsystems work in order to provide vehicle stability and control. However, the optimum driving dynamics can only be achieved when the tire forces on all wheels and in all three directions can be influenced and controlled precisely. This level of control requires that the vehicle is equipped with various chassis control systems that are integrated and networked together. Drive-by-wire electric vehicles with in-wheel motors provide the ideal platform for developing the required control system in such a situation. The focus of this thesis is to develop effective control strategies to improve driving dynamics and safety based on the philosophy of individually monitoring and controlling the tire forces on each wheel. A two-passenger electric all-wheel-drive urban vehicle (AUTO21EV) with four direct-drive in-wheel motors and an active steering system is designed and developed in this work. Based on this platform, an advanced fuzzy slip control system, a genetic fuzzy yaw moment controller, an advanced torque vectoring controller, and a genetic fuzzy active steering controller are developed, and the performance and effectiveness of each is evaluated using some standard test maneuvers. Finally, these control systems are integrated with each other by taking advantage of the strengths of each chassis control system and by distributing the required control effort between the in-wheel motors and the active steering system. The performance and effectiveness of the integrated control approach is evaluated and compared to the individual stability control systems, again based on some predefined standard test maneuvers. iii Acknowledgements This research has been carried out in the Motion Research Group at the University of Waterloo, in Canada. I am pleased to acknowledge the financial support that I received from AUTO21, a Canadian Network of Centres of Excellence, and the Natural Sciences and Engineering Research Council of Canada (NSERC). The financial support from these organizations allowed me to focus on my research and carry it out to completion. There are a number of people to whom I would like to express my gratitude. First of all, I owe a great deal of gratitude to my supervisors, Prof. Steve Lambert and Prof. John McPhee, for giving me great freedom in selecting my research topics and who, through a combination of patience and persistence, have enabled me to grow more than I knew possible during the course of my Ph.D. This work is a result of their unlimited support and encouragement, and the faith they put in me. It was a long journey that I‟m happy to have experienced. Special thanks go to the present (Tom Uchida, Matthew Millard, Sukhpreet Sandhu, Ramin Masoudi, Willem Petersen, Joydeep Banerjee, Mohammad Sharif Shourijeh, Mohammadreza Saeedi, and Mike Boos) and past (Kevin Morency, Mathieu Léger, Mike Wybenga, Adel Izadbakhsh, William Bombardier, Akram Abdel-Rahman, Dr. Nasser Azad, Dr. Yi Liu, and Dr. Chad Schmitke) lab mates at the Motion Research Group. I have had a great time working with you guys and hope that we keep in touch in the future. Tom Uchida, I had a great time working with you and, without your enthusiasm, patience, and constant support, this thesis would be neither half as good nor half as finished by now. I hope I will be able to repay you soon. Chad Schmitke, it was my honor to work with you on a variety of projects, and I thank you for your support throughout my thesis. Kevin Morency, thank you for the great support you provided me during your stay in Waterloo. It was a great time having you as my lab mate and roommate at the same time. Last but not least, I would like to thank my parents, Robabeh Djalali and Amir Hossein Jalali, for the unlimited love and support you provided me throughout my life. I am who I am just because of you. Without your unconditional support, care, and belief in iv me, I would not have made it this far in life. You have been there for me every step of the way and have aided me through all of my decisions. Thank You! Waterloo, April 2010 Kiumars Jalali v Dedication This thesis is dedicated to my father, who has raised me to be the person I am today. You have been with me every step of the way, through good times and bad. Thank you for all the unconditional love, guidance, and support that you have always given me, helping me to succeed and instilling in me the confidence that I am capable of doing anything I put my mind to. Thank you for everything. I love you! vi Table of Contents List of Figures .............................................................................................................. x List of Tables .......................................................................................................... xxiii 1 Introduction and Background .............................................................................. 1 1.1 State-of-the-art drive-by-wire technologies ............................................................ 4 1.1.1 Brake-by-wire systems .............................................................................................................5 1.1.2 Steer-by-wire systems .............................................................................................................7 1.2 Conventional slip control systems .......................................................................... 9 1.2.1 Anti-lock braking system........................................................................................................10 1.2.2 Traction control system .........................................................................................................11 1.2.3 Methods of adjusting the tire slip ratio .................................................................................12 1.3 Conventional stability control systems ................................................................. 13 1.3.1 Braking-based electronic stability control system .................................................................15 1.3.2 Steering-based electronic stability control system ................................................................17 1.3.3 Torque vectoring control system ...........................................................................................20 1.4 Advanced stability control system through networked chassis .............................. 25 1.5 Thesis outline and contributions ........................................................................... 29 2 Test Maneuvers and Analytical Driver Models .................................................... 31 2.1 Test maneuvers for evaluating vehicle handling and performance ......................... 33 2.1.1 Selection and evaluation of chosen test maneuvers .............................................................35 2.1.2 Comprehensive evaluation of chosen test maneuvers .........................................................41 2.2 Modelling the behaviour of a driver ..................................................................... 42 2.2.1 Development of a path-following driver model ....................................................................44 2.2.2 Development of a speed-control driver model .....................................................................50 2.3 Evaluation of the path-following and speed-control driver models ........................ 52 3 Advanced Fuzzy Slip Control System ................................................................... 60 3.1 Conventional slip control systems ........................................................................ 61 3.2 Development of an advanced fuzzy slip control system ......................................... 62 3.3 Evaluation of the advanced fuzzy slip control system ............................................ 71 vii Table of Contents 3.4 Chapter summary ................................................................................................ 78 4 Genetic Fuzzy Yaw Moment Controller ............................................................... 80 4.1 Simplified vehicle model with in-wheel motors ..................................................... 81 4.2 Soft computing and hybrid techniques ................................................................. 83 4.3 Fuzzy yaw moment controller design .................................................................... 90 4.4 Evaluation of the fuzzy yaw moment controller ...................................................
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