Double-layer Dynamic Decoupling Control System for the Yaw Stability of Four Wheel Steering Vehicle

Abstract

The four-wheel steering (4WS) is an efficient method to improve the manoeuvrability of electric vehicle with the tendency of understeer, by providing the sufficient steering angles. Because of the various kinds of driving environments, the inner coupling between the active front and rear wheels of the 4WS vehicle is a challenging problem, which usually results in unstable yaw stability of the vehicle. In order to solve this coupling problem, this paper presents a double-layer dynamic decoupling control system (DDDCS), which consists of an upper part-dynamic decoupling unit (DDU) and a lower part-steering control unit (SCU). The DDU is presented to solve the dynamic coupling problem between the active front and rear wheels, and separately establishes two decoupled models by the diagonal decoupling method. The SCU is designed to obtain the decoupled control signals by the model predictive controller, then, the yaw stability of 4WS vehicle can be guaranteed. The results of the simulation show that the proposed DDDCS has good decoupling performance and stable yaw performance for 4WS vehicle.