Optimal Operation Point Detection Based on Force Transmitting Behavior for Wheel Slip Prevention of Electric Vehicles

The optimal wheel slip prevention control of ground vehicles aims at maintaining the operation point around the optimal one to achieve the maximum adhesion utilization, which contributes not only to ensure the adhesion stability but also to obtain the optimal traction performance, particularly being useful for the low grip conditions. However, the uncertainty of tire-road contacts brings great challenges for the optimal operation point determination. This paper proposes a novel methodology for the online search of the optimal operation point under uncertain low grip conditions. First, the force transmitting behavior is analyzed in the stable adhesion state and the unstable slipping state. Then, a determination law to identify the optimal operation point via investigating the adhesion force is proposed, which functions during the transient process from the stable region to the unstable region under the action of an increasing drive force. The adhesion force is estimated using the wheel rotational speed and the wheel drive torque. Both the simulation and experimental results verify the effectiveness of the proposed methodology.