Research On Coordinated Control Of Differential Power And Lateral Stability For Distributed Drive Electric Vehicles

Electric vehicles are the products of the three major development trends in the world today:energy conservation,environmental protection and safety.At the same time,their emergence can alleviate the problem of environmental pollution and energy shortage.Therefore,the mainstream development of the automobile industry today is electric vehicles.Among them,distributed drive electric vehicles have the characteristics of independent and controllable wheel torque,which can make more dynamic control of electric vehicles,which has become a hot spot in dynamic analysis and control direction.This paper first studies the differential power steering control of distributed drive electric vehicles,and then studies its yaw stability.Finally,the two dynamic control are coordinated to lay the foundation for the coordinated research of multi-control systems.Firstly,the basic principle of differential power steering is analyzed,and the vehicle steering system model and the ideal power assist characteristic model are established to obtain the ideal steering wheel torque during the vehicle steering.Combining the fuzzy PID control strategy with the variable universe method,the three PID control parameters are adjusted according to the torque deviation and the deviation change rate to realize the adaptive control of the left and right steering wheel torque difference.The torque distribution control calculates the driving or braking torque of the left and right wheels based on the torque difference between the left and right wheels and the wheel driving torque.The design of the optimal slip ratio control method of the wheel is used to ensure the stability of the vehicle.The digital simulation results based on CarSim and MATLAB/Simulink prove that the vehicle steering lightness improvement under the variable universe fuzzy PID control is up to 43.5%,which is better than the traditional PID control,and the rms error of the yaw rate and the expected value is only 0.212 rad./s,and the wheel slip rate is lower.Then,the basic principle of yaw moment control is analyzed,and the linear two-degree-of-freedom model is established to obtain the ideal yaw rate of the vehicle.Based on the running state of the steady-state steering of the vehicle,the vehicle yaw rate is used as the control target,and the sliding mode is used.The control algorithm designed the yaw moment control system of the distributed drive electric vehicle,and compared with the traditional PID control algorithm.The results show that the error of the yaw rate and the expected value under the control of no control,PID control and sliding mode variable structure are both The square roots were 0.039 rad/s,0.021 rad/s,and 0.015 rad/s,respectively,which improved by 46.2%and 61.5%,respectively.And the PID control and sliding mode variable structure control is improved by 14.9%and 10.4%with respect to the maximum value of the centroid side angle.It shows that the designed sliding mode variable structure controller can effectively improve the stability of the vehicle.Finally,based on CarSim and Matlab/Simulink software,a dynamic joint simulation model of distributed drive electric vehicles is established.At the same time,according to the basic principles of differential power steering control and yaw moment control and their interconnection,the two are coordinated and controlled.The yaw stability control is the main part,and the joint coordinated control system of differential power steering is partially considered.The hardware-in-the-loop test is carried out by using double-shift line and steering wheel angle sine wave input form.The test results show that the designed differential power steering and yaw moment coordination control algorithm can take into account the vehicle's power-assisting ability under the premise of ensuring vehicle stability.