Design of Four Wheel Steering and Direct Yaw Moment Control for Unmanned Vehicle with Path Tracking Controller in Extreme Maneuvers

This paper concentrates on the path tracking and dynamic control of unmanned four-wheel steering (4WS) and four-wheel independent drive (4WID) vehicles in extreme maneuvers with high lateral acceleration. First, an adaptive model predictive control (AMPC) controller is utilized to track the target path. And to improve the lateral force response and zeroize sideslip, a sliding mode (SMC) 4WS controller is built to control the steering angle of wheels considering the Ackermann geometry. For direct yaw moment control (DYC), another SMC controller is designed for the additional yaw moment to track the target yaw rate, and the friction ellipses of wheels are considered in the allocation of wheel torques to average the utilization of adhesion. Moreover, to evaluate these control strategies in transient and steady states, several maneuvers including ISO 3888-1 and 3888-2 are built in CarSim, and the improvements of 4WS and DYC are verified separately. Results have proved that 4WS together with DYC can strengthen the response of lateral forces and yaw rate, and the path following performance as well as the vehicle stability are improved.