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.