Chassis Coordinated Control for Full X-by-Wire Four-Wheel-Independent-Drive Electric Vehicles

Abstract

In this paper, a full X-by-wire chassis coordination control scheme is proposed by synthetically utilizing the Direct Yaw-moment Control, Active Front Steering, Anti-Slip Regulation and Active Roll Control to improve the longitudinal, yaw and roll stability. First, a vehicle state prediction module is established to predict vehicle yaw and roll stability and to generate three reference vehicle states, i.e., the desired roll angle, yaw rate and longitudinal velocity. Then, a decentralized event-triggered discrete sliding mode control scheme is developed to track these reference states by coordinating the X-by-wire subsystems based on their respective effective working areas. For yaw rate control, dynamic torque regulation factors are introduced to prevent wheel slip and lock-up based on real-time slip ratio feedback. Under longitudinal driving conditions, a robust sliding mode control and a hybrid control-based method are used under emergency acceleration or braking conditions. The hardware-in-the-loop (HIL) tests under the slalom, double lane change and fish hook tests show that the proposed chassis coordinated control scheme can comprehensively improve vehicle ride comfort, handling performance, longitudinal and lateral stability, and rollover prevention ability.