Design of vehicle stability control of distributed-driven electric vehicle based on optimal torque allocation
This paper presented a hierarchical vehicle-stability-control design based on the longitudinal force distribution optimization for the handling and stability control of the distributed-driven electric vehicle. The 8-DOF vehicle model and the three-layer control system were developed. By selecting the sideslip angle and the yaw rate as the state variables and introducing the virtual control to decouple two control variables, the upper controller adopted the integral 2-DOF vehicle model to calculate the equivalent yaw moment for the vehicle stability. Under the restrictions of the vehicle actuators, the middle controller utilized the linear quadratic optimization (LQR) method to optimize the distribution of the front and rear steering angles and the tire longitudinal forces. The sliding-mode-based slip controller in the lower layer was also designed to reallocate the wheel torques. A simulation test was carried out to verify the effectiveness of the proposed design. Results show that the control system can make the vehicle follow the expectation effectively and enhance the vehicle handling and stability in extreme conditions with high speed as well as its active safety under the actuator failures.