Improving in Traction Performance of Motor-Assisted-All-Wheel-Drive Vehicle by Using Acceleration Based Slip Ratio Control

Abstract

A new method of slip ratio control to improve traction for all-wheel-drive vehicle utilizing vehicle acceleration together with the time derivative of the slip ratio is proposed. This control method automatically suppresses the increase of slip ratio whenever it is over the optimum, such as in case where the target slip ratio becomes higher than the optimum. The control is based on vehicle acceleration for adaptability to all-wheel-drive vehicles, where conventional wheel speed based control had difficulty when all-wheel went into a wheel spin. The new control method was implemented into an electrical-motor-assisted-all-wheel-drive vehicle and showed improved low-friction-traction performance.