Pitch reduction and traction enhancement of an EV by real-time brake biasing and in-wheel motor torque control

This paper focuses on pitch control in braking and traction enhancement in acceleration. During braking the vehicle pitches, which greatly determines the ride comfort; on the other hand, during acceleration an optimum value of wheel slip is desired for better traction. In the first part, we control the vehicle pitch of a Fox electric vehicle by real-time brake biasing. We begin with determining side view swings arm centre positions as a function of wheel travel for both front and rear suspensions. Next using these instantaneous centres, vehicle pitch point is determined and the mathematical model for vehicle pitching is developed. Finally, a PD controller is developed which minimises vehicle pitch using brake biasing. In the second part, the motor torques are controlled by maintaining a constant wheel slip at which maximum longitudinal force is generated. The results show significant reduction in vehicle pitch and better tracking of desired velocity profile.