关键词: 轮毂电机独立驱动汽车, 行驶稳定性, 滑模变结构控制, 转矩分配

Abstract: Aiming at the characteristics of decoupling and controllable wheel torque of four-wheel-independent-driven electric vehicles, the influence of the vehicle force during the steering process on the lateral stability of the four in-wheel independent-drive electric vehicle is analyzed, and the steering stability control strategy of the four in-wheel independent drive electric vehicle is proposed, which provides an idea for the torque coordinated control of four-wheel independent-drive vehicles for the improvement of vehicle lateral stability. Based on the idea of model tracking control, the controller is designed by the hierarchical structure. The controller includes a reference model, an upper controller, and a bottom control allocator. A 2 degrees of freedom model with centroid deflection is used as the reference model to design a novel nonlinear sliding mode variable structure motion upper controller. This method could realize the decoupling control of vehicle yaw rate and sideslip angle to a certain extent, and avoid large changes of yaw rate and sideslip angle, thus ensuring vehicle stability. In the bottom control allocator, the optimal allocation method based on maximizing tire stability margin is adopted. In Carsim, a four-wheel hub motor electric vehicle model was built and Simulink was used to build a control strategy model to carry out Carsim/Simulink joint simulation. The double lane change test results show that the sliding mode variable structure controller has better convergence, and the allocation module can realize the optimal distribution of the four wheel torque, which can increase the stability of the vehicle under the limit condition. The study will provide theoretical support for the distributed coordinated control of wheel motor independent-drive vehicle.

Key words: in-wheel motor independent-drive vehicle, lateral stability, sliding mode variable structure control, torque allocation