Research On Differential Control Of Wheel Driven Light Commercial Vehicle Chassis

The hub drive is a new type of arrangement that integrates the drive motor into the wheel hub of the car.It changes the form of the centralized arrangement of the conventional pure electric vehicle motor,and the drive wheel and brake torque of the drive wheel can be independently controlled.Since the wheel-driven electric vehicle chassis eliminates the conventional mechanical differential,how to coordinate the differential steering relationship between the drive motor and each drive wheel becomes a key issue in determining the steering stability and driving safety of the vehicle.This research originated from the industry commissioned topic "In-wheel motor driven pure electr^ic light vehicle chassis and key technology research and development" aiming to develop pure electric wheel drive chassis for light commercial vehicles,to achieve differential control of the whole vehicle and improve steering stability.The work highlighted in this study is as follows:First,the platform concept is adopted to propose an expandable wheel drive chassis design for light commercial vehicles.Based on the characteristics of the hub motor drive chassis,combined with the electric vehicle parameter matching method,the parameter matching calculation of the vehicle and the power system ensures the rationality of the chassis parameters.The ADAMS/CAR software was used to establish a multi-body dynamics model for subsequent simulation analysisSecond,the mathematical model of vehicle dynamics is calculated,combined with the principle of electronic differential steering control,and the differential steering control strategy proposed by PID closed-loop feedback control is adopted.The strategy calculates the ideal yaw rate based on the longitudinal travel speed of the vehicle and the steering wheel angle.The difference between the ideal yaw rate and the actual yaw rate is obtained by the PID controller and the additional torque is added to the correct one.Driving the wheel to achieve differential steering control.Based on the above control method,the differential control strategy model is established in MATLAB/Simulink,and the joint simulation model is composed with the vehicle multi-body dynamics model.Third,based on the three conditions of steady-state rotation,steering return and steering portability,the steering stability test of the wheel-driven prototype was carried out.The combined simulation results are used to evaluate the effectiveness of the above modeling method and differential control method.The results show that the test has a total score of 86.46,and the steering stability is good.The simulation and experimental results are similar in overall,and the joint simulation model has higher accuracy.In addition,the differential control strategy using PID closed-loop feedback method can better ensure the vehicle's manipulation.stability.Fourth,the co-simulation is 'used to analyze the steering characteristics of the differential control.Combined with the evaluation method of steering stability,the evaluation index which can accurately reflect the movement characteristics of the hub drive chassis is established;the steering wheel angle and the yaw rate are selected in three conditions of double shift line condition,serpentine condition and steering wheel angle step.The response of the body roll angle and lateral acceleration is used as the evaluation index.The steering characteristics of the hub drive chassis are analyzed,and the joint simulation model is established and simulated.The analysis results show that the four evaluation,indexes of the three working conditions have different degrees of reduction after adding the differential control strategy,which verifies that the differential control strategy improves the steering stability and driving safety of the whole vehicle.