New Control Method of Four-Wheel Independent Driving Electric Vehicles for Anti-Slip Purposes 2020-01-1420
The performance of electric vehicles could be enhanced by more flexible drivetrain configurations combined with advanced control method. Based on the four wheel independent driving and front and rear axle modular steering configuration, which was proposed by our research group last year, the problem of slippery under close-to-limit conditions are further discussed and simulated. A new torque vectoring method based on obtainable parameters and variables in real driving situations is introduced to reduce the sideslip when turning on low friction coefficient surfaces or with high speed. This method is developed from a comprehensive index, which reflects the stability and maneuverability, by adding additional torques when stability could not be compensated enough by basic torque vectoring. Besides, an improvement of adding a simu-Torsen differential mechanism is made to the model of the vehicle, which enables another control method with the same purpose as before. This method is combined with the torque vectoring and the active control to switch on the simu-Torsen differential mechanism. All the control methods were validated with a real SUV based Simulink model. The vehicle responses with each control method and without such controllers are compared to describe its strengths in detail. Both control method could help the vehicle keep the designated speed and turning curvature without losing its attitude or severe sideslip or even rollover. The method with simu-Torsen differential mechanism would have a better robustness as it is designed to be able to be operated manually during system malfunction while the other one could reduce the wear and tear of the tyres.
Chen Liu, Gangtie Zheng
University of Cambridge, Tsinghua University