Wire-controlled Front-wheel Steering Electric Wheel Drive Vehicle Extreme Working Conditions Drift Avoidance Control

The advantages of the steer-by-wire system and the electric wheel drive system include fast response and precise control.The steer-by-wire system can quickly rotate the wheels to the desired angle position,while the electric wheel drive system can accurately provide driving/braking torque to the wheels.Studying tire saturation characteristics during vehicle steering has always been a focus of the academic community to achieve fast and stable obstacle avoidance control of the entire vehicle.Therefore,this article uses a steer-by-wire electric wheel drive car to study the vehicle’s steady-state drift obstacle avoidance problem under extreme conditions.The main content is divided into four parts:(1)Building models for the steering motor and steer-by-wire system,electric wheel drive system,magic tire model,and multi-degree-of-freedom coupled model of the entire vehicle;selecting the angle step response condition to simulate and verify the entire vehicle model,using the Car Sim vehicle model as a reference to verify the reliability of the built vehicle model.(2)Analyzing the collaborative control role of the steer-by-wire system and the electric wheel drive system during the vehicle drifting process,clarifying the dynamic change law of the vehicle during drifting process;designing a steady-state drift tracking controller to track and control the parameters of the vehicle in a stable drifting state;selecting multiple vehicle speed and road adhesion coefficient conditions to simulate and verify the steady-state drift tracking controller,verifying the tracking and control effect of the controller on the vehicle drifting state parameters.(3)A driving risk field model was established using the potential field method.Then,the driving risk field was transformed into an objective function,and an optimized solution was obtained using the model predictive control algorithm for path planning and control under straight line conditions.During obstacle avoidance,the potential field method was used for model prediction and co-control with the steady-state drift algorithm to fully utilize the tire force during the vehicle turning process.Finally,the steady-state drift obstacle avoidance strategy was simulated and verified.(4)A controller was designed and constructed for testing on a closed-loop platform.The stable drifting avoidance algorithm developed in the previous section was selected and tested in various driving scenarios to verify the effectiveness and reliability of the proposed control strategy for achieving stable avoidance of obstacles under extreme driving conditions.During obstacle avoidance,the potential field method prediction and the stable drifting algorithm are used in a coordinated manner to make full use of the tire force during vehicle steering.Finally,the stable drifting avoidance strategy is simulated and verified.This study proposes a stable drifting avoidance control strategy for the problem of emergency obstacle avoidance in vehicles under extreme driving conditions.Through simulation verification results in various driving scenarios and closed-loop testing of the controller,the proposed strategy can accurately control the steering angle of the front wheels and the degree of saturation of the tire force on the rear wheels,enabling the vehicle to quickly and stably avoid obstacles during emergency situations.The research results of this paper provide theoretical reference for the study of tire performance in electric vehicles with steer-by-wire system under extreme driving conditions.