Extension coordinated control of four wheel independent drive electric vehicles by AFS and DYC

In this paper, a new extension coordinated controller was proposed for driving stability and handling performance of four wheel independent drive electric vehicles. The proposed controller has three levels. The upper control level uses a new extension coordinated controller to find the weights of a active front wheel steering controller (AFS) and a direct yaw moment controller (DYC). Moreover, considering the different vehicle speed, the road adhesion coefficient and the wheel steering angle, a phase plane method was used to provide the dynamic stability boundary for the switching control strategy of AFS and DYC. The medium control level used the triple-step nonlinear method to calculate the additional front wheel angle and additional yaw moment required by the lower control level. The additional front wheel angle and additional yaw moment was applied to the steering motor and the four wheel drive motor, respectively. In order to obtain the target wheel force, the four wheel drive torque was optimized based on a quadratic programming method. The proposed extension coordinated controller was performed in the CarSim/Simulink co-simulation platform, hardware-in-loop (HIL) and vehicle test. The results showed that the proposed controller can effectively improved both the stability and handling performance.