A Robust Wheel Slip Control Design with Radius Dynamics Observer for EV

In order to improve the safety and dynamic performance of electric vehicles equipped with four in-wheel electric motors, and prevent the wheels from locking or slipping when braking or accelerating, a new longitudinal control strategy which combines ASR traction and ABS braking control is proposed using an observation algorithm of effective radius for four wheel of electric vehicle. Using the electric motor torques as the unique actuator signal sources, this combined ASR/ABS can act as acceleration slip regulation (ASR) by preventing the wheels from slipping during acceleration and as an antilock braking system (ABS) by preventing the wheels from getting locked during braking. A variation of effective radius of the wheel’s tire can have an incidence on the longitudinal and lateral control. Moreover, the wheel effective radius observer based on high order sliding mode approach using the information of the electric motor torques and the angular velocities is used in the combined ASR/ABS systems. First, adjusting the motor torque and based on Fuzzy logic control, the acceleration slip regulation (ASR) is designed to maintain the wheel slip in the optimal range using the angular acceleration and slip rate. Second, for limiting the wheel slip by adjusting the motor torque the sliding mode control is used. Several Matlab/Simulink simulation tests will be carried out to validate the effectiveness of the proposed controller.