2009-01-0435 Integrated Stability Control System for Electric Vehicles with In-wheel Motors using Soft Computing Techniques Kiumars Jalali, Thomas Uchida, John McPhee and Steve Lambert University of Waterloo Copyright © 2009 SAE International ABSTRACT An electric vehicle model has been developed with four direct-drive in-wheel motors. A high-level vehicle stability controller is proposed, which uses the principles of fuzzy logic to determine the corrective yaw moment required to minimize the vehicle sideslip and yaw rate errors. A genetic algorithm has been used to optimize the parameters of the fuzzy controller. The performance of the controller is evaluated as the vehicle is driven through a double-lane-change maneuver. Preliminary results indicate that the proposed control system has the ability to improve the performance of the vehicle considerably. INTRODUCTION In the last two decades, advances in electronics have revolutionized many aspects of the automobile. Of particular focus have been the areas of engine management and vehicle dynamics safety systems such as anti-lock braking systems (ABS), traction control systems (TCS), electronic stability programs (ESP), and active steering (AS) systems. These safety systems involve the use of electronic control units to adjust the brake, accelerator, and/or steering inputs provided by the driver in order to control the slip of individual tires during emergency braking (ABS) or maneuvering (TCS), or to control the vehicle yaw rate and sideslip angle either by braking individual wheels (ESP) or by manipulating the steering angle of the wheels (AS). For further information on different strategies for influencing the yaw dynamics of a vehicle using differential braking and active steering systems, see [1-3]. According to a recent study conducted by the Insurance Institute for Highway Safety, ESP systems have the potential to reduce the risk of fatal single-vehicle crashes by 56%, the risk of fatal multi-vehicle crashes by 17%, and the risk for all fatal vehicle crashes by 34% [4]. A similar investigation performed by the Institute for Traffic Accident Research and Data Analysis in Japan suggests that ESP can reduce single-vehicle accidents by 35%, head-on collisions with other vehicles by 30%, and the number of casualties per year resulting from single-vehicle crashes and head-on collisions by 35% [5]. As a result, the U.S. National Highway Traffic Safety Administration has mandated that ESP be implemented on all passenger cars and light trucks by 2012 [6]. Another recent development in the automotive industry is the electric vehicle (EV), which has attracted a great deal of interest as an environmentally- and energy-conscious means of providing personal transportation. Thanks to substantial improvements in electric motor and battery technologies, EVs now have driving performance metrics that make them viable alternatives to traditional internal combustion engine vehicles in some markets. Furthermore, EVs are more versatile platforms on which to apply advanced motion control techniques, since the motor torque and speed can be generated and controlled quickly and precisely. In fact, the torque response of an electric motor is on the order of a few milliseconds and, therefore, responds 10 to 100 times faster than the internal combustion engines and hydraulic braking systems in use today [7]. The use of small but powerful direct-drive in-wheel motors allows for the implementation of the most advanced torque vectoring system possible, in which any desired torque distribution between the four wheels can be realized. Such a platform also represents the most advanced all- SAE Int. J. Passeng. Cars - Electron. Electr. Syst. | Volume 2 | Issue 1 109Downloaded from SAE International by University of Minnesota, Tuesday, July 31, 2018wheel-drive (AWD) system, generating the optimal amount of traction on each tire by controlling the speed of the motors. The Hy-wire concept car de