Stability Control System Design For Distributed Drive Electric Bus

City bus belongs to commercial vehicle,due to its own structural characteristics,it is easy to lose stability and cause serious traffic accidents.Therefore,more and more attention has been paid to the stability control system applied to commercial vehicles.In recent years,distributed electric buses have been popularized because of their flexible control and efficient transmission.As a new public transport vehicle,there are few stability control systems that consider the independent drive/braking control characteristics of each drive wheel in distributed electric buses.Based on university-enterprise cooperation production electric bus project,this paper takes the distributed rear-drive electric bus as the research object,establishes the whole vehicle dynamics model,and designs the stability coordination control system of the distributed rear-drive electric bus,including vehicle parameter estimation,drive anti-skid control,yaw stability control and roll stability control module.Considering the obvious variation of the vehicle mass and the four-wheel vertical load,the least square method was used to estimate the vehicle mass,and the four-wheel vertical load was estimated according to the vehicle driving dynamics equation,which provided a foundation for the implementation of the subsequent control strategy.In the roll stability control strategy,the lateral load transfer rate is used as the index to judge whether the passenger car will roll over or not.Fuzzy control is used to calculate the additional yaw moment and brake the target wheel.The controller takes the sideslip and sideslip velocity error as input.The designed yaw stability control strategy takes yaw angular velocity and centroid lateral deflection angle as the indexes to evaluate the yaw stability of passenger cars,and adopts fuzzy control algorithm to design the controller.The designed acceleration slip control strategy takes the slip rate deviation of the drive wheel as input and calculates the target wheel driving torque that can provide the maximum adhesion through sliding mode control.The coordinated control strategy is designed to coordinate the working interval of each strategy according to different vehicle driving conditions.By using MATLAB/Simulink and Truck Sim joint simulation,a variety of vehicle driving conditions and road conditions were designed,and the parameter estimation and stability coordination control strategies were verified by software in the loop.The simulation results show that the estimated results of vehicle mass and four-wheel vertical load fit well with the actual value,and the average maximum error is within3%.For the split road and butt road,the designed acceleration slip control strategy can effectively reduce the torque of the drive wheel.For high speed and low adhesion condition,the designed yaw stability control strategy can effectively reduce the amplitude of yaw angular velocity and the deflection angle of the center of mass.For high speed and high adhesion condition,the roll stability control strategy can effectively reduce the rolling tendency of vehicles and ensure the stability of vehicles.The NI PXIe-8880 real-time control cabinet and the NI PXI-8512 board were used to communicate with DSP controller,driver control mechanism and executive mechanism by CAN for HIL test to verify the feasibility of the algorithm,real-time performance and stability of controller communication.The HIL test results are in good agreement with the simulation results.