Research On Stability Control Strategy For Distributed Drive Vehicles In Straight Driving

With the advancement of science and technology and the development of society,electric vehicles are playing an increasingly important role in people’s daily lives.Most electric vehicles employ four-wheel independent drive,which differs from traditional mechanically connected gasoline cars,as it utilizes electronic control to independently regulate the output torque of each tire.Electric vehicles offer advantages such as simpler structure,reduced noise,lower environmental pollution,and increased intelligence compared to fuel-powered vehicles.However,due to the adoption of hub motors in most four-wheel independent drive electric vehicles,where the vehicle’s power,transmission,and braking functions are integrated into a single motor design,the rational distribution of torque for each hub motor on different road surfaces has become a hot topic in current electric vehicle research..(1)This study performs parameter identification on an actual vehicle and subsequently establishes a four-wheel independent drive vehicle dynamics model in the Carsim vehicle dynamics simulation software based on the identified parameters.Then,an electric motor model is built in Matlab/Simulink.Once the electric vehicle simulation model is constructed based on the actual vehicle,the vehicle’s acceleration performance and straight-line driving capability are validated through simulations.(2)Based on the different lateral force conditions acting on the vehicle when it deviates from its intended path and considering the tire slip ratio,an analysis is conducted to outline the factors and operating conditions that affect the straight-line stability of the vehicle.Ultimately,the control variables for the entire coordinated control strategy are determined as vehicle speed,yaw rate,and tire slip ratio.These variables are selected based on their significant influence on the vehicle’s stability during straight-line driving.(3)Build the control strategy for the simulated vehicle model.The control strategy in this paper is mainly based on the GA-BP algorithm to optimize the proportional integral and differential parameters of the PID controller.The control system is mainly composed of upper and lower controllers.The upper controller includes the vehicle speed Tracking controller,yaw rate controller and ASR drive anti-skid controller respectively correct and control the vehicle speed,yaw rate and slip rate in real time.The lower controller is compos ed of a torque distribution controller,which mainly coordinates and distributes the three torques generated by the upper controller to the four wheels.(4)The GA-BP-PID-based control strategy,no control strategy and BP-PID control strategy are coupled with the vehicle model,and the vehicle motion parameters controlled by the three simulation strategies are analyzed in depth under different working conditions.The final simulation results show that under the conditions of high and low adhesion coefficient road surfaces and static and steady-state errors of the motor,the speed tracking ability of the simulated vehicle based on the GA-BP-PID control strategy is better without overshooting,and the vehicle generated The yaw rate and the amount of deviation are the smallest;on the open road with the largest degree of deviation of the simulated vehicle,the final deviation of the vehicle under no control strategy and BP-PID control strategy is 11.52 m and 0.37 m,GABP-PID The final deviation of the simulated vehicle under the control strategy is 0.28 m.Therefore,under the action of the GA-BP-PID control strategy,the stability of the simulated vehicle has been significantly improved,and the safety has also been further enhanced.Finally,the dynamic characteristics of the simulated vehicle and the experimental vehicle are compared through the snake test to verify the accuracy of the simulated vehicle model.