Stability control based on three-dimensional portraits for four-wheel-independent-drive EV

Abstract

In this paper, a two-stage expectation stability controller was proposed for driving stability of four wheel independent drive electric vehicles. The proposed controller has three levels. There were three steps to the stability control of the vehicle. First, the three-dimensional state portraits were drawn based on the 14DOFs vehicle model and used the stem equation to find two-stage expectation. The surface was derived from the analysis of the tire-road adhesion divides the portraits into safe areas and unsafe areas. Second, the stability controller with sliding mode algorithm was designed. When the state parameter is in the unsafe areas, the safe boundary surface is taken as the first-stage expectation; after the system enters the safe areas, the stem is taken as the second-stage expectation. Then the fuzzy algorithm is applied to distribute the control demand of yaw moment to generate the torques of each in-wheel motor. Finally, simulation verification is performed in Simulink-CarSim co-simulation environment. The simulation results show that the designed control strategy can improve the lateral stability while the loss of longitudinal speed is within 3.25%.