Vehicle stability control of electric vehicle with slip-ratio and cornering stiffness estimation

Electric vehicles have attractive potential in vehicle stability control. In traction control systems, it is generally required to detect vehicle speed in order to obtain the slip- ratio. However, it is hard to measure vehicle speed directly. In the first part of this paper, novel estimation method of slip-ratio is proposed without detecting the vehicle speed. The estimation accuracy is improved by considering the driving resistance. Based on this estimation, a slip-ratio controller is developed with feedback linearization. In the second part, a simple DYC is proposed which can identify the front and rear cornering stiffness independently without slip-angle observer. The advantages of proposed methods are verified by simulations and experiments with an electric vehicle which has two in-wheel motors.