Coordinated Control Strategy of EPS and TCS for Four-Wheel Drive Vehicle

Focusing on the coupled dynamics between electric power steering (EPS) system and traction control system (TCS) and in order to improve the steering stability and dynamic performance of the four-wheel drive vehicle, a hierarchical coordinated control strategy of EPS and TCS was proposed. Firstly, a high-order and nonlinear dynamic model was built based on an eight-degree of freedom vehicle model. The control strategy of EPS and TCS was introduced shortly and respectively. The upper coordinated controller was designed without a change in EPS and TCS controller. Based on the feedback of status information and control logic of the vehicle system, the upper coordinated controller modified the decision of EPS and TCS controller and coordinated the coupled effect between EPS and TCS, which realized the vehicle's optimal comprehensive performance. Finally, the off-line simulation experiments for coordinated control strategy were carried out under different working conditions. The results show that the coordinated control strategy of EPS and TCS can effectively improve the vehicle steering stability and longitudinal acceleration performance, thus the effectiveness of the proposed control strategy is verified.