Research on steering coordination control strategy for distributed drive electric vehicles

The key problems of the steering system and vehicle handling stability of distributed drive electric vehicles are studied in the paper. According to the performance of the distributed drive electric vehicle, a seven-degree-of-freedom is established to match the parameters with the model of CarSim software. Based on the maneuverability improvement control algorithm of the active front wheel system [Active Front Steering (AFS)]/differential power steering system coupling redundancy between differential drive assist steering (DDAS), a AFS/DDAS system coordination control strategy is formulated to reduce the influence of undesirable cross-pendulum moments on vehicle stability. Through the requirements for vehicle stability, a distributed control strategy for the steering stratification of electric vehicles is developed. In the upper layer, the direct transverse moment controller is designed by the linear quadratic regulator algorithm, and the stability control area is divided into a stable region, a transition region, and an unstable region according to the center-of-mass deviation angle. Then the weights of the three subsystems are determined by judging the control area of the vehicle. The lower controller distributes the additional torque from the final calculation of the upper controller to the driving wheels through an allocation algorithm. Finally, using the CarSim/Simulink simulation platform and the dSPACE hardware-in-the-loop real-time simulation platform, the effectiveness and real-time performance of the steering coordination control strategy are verified by simulation experiments under typical working conditions, such as double shift line, step, and sinusoid.