Research On Sliding Mode Control Strategy Of Four-wheel Active Steering By Wire Based On Multi-agent

Four wheel steering technology is an active chassis control technology that improves the vehicle’s handling stability and driving safety by changing the steering angles of the front and rear wheels,as well as the left and right wheels.The control strategy of the fourwheel active steering vehicle studied in this paper is mainly based on the vehicle lateral dynamics characteristics and control considerations.Aiming at the multi actuator coupling,tire nonlinear characteristics,modeling uncertainty,interference,etc.in the four-wheel active steering system,a multi-agent based Sliding mode control method for the four-wheel active steering system is proposed.Sliding mode control has strong anti-interference ability,and Sliding mode control can improve the robustness of the system.In response to the shortcomings of existing technologies,the purpose of this new design is to propose a finite time steering control strategy based on multi-agent event triggering,in order to ensure that the four-wheel steering system tracks the ideal yaw rate in a finite time and achieve stability control of the entire vehicle.(1)Based on the principles of automotive dynamics and geometry,a model of a four wheel independent steering system was established,achieving dimensionality reduction of the model.Considering four independent wheel steering systems as four heterogeneous agents,a topology structure of the four independent wheel steering system was established based on the communication and hardware connections between the four independent wheel steering systems.(2)Aiming at the unknown uncertainty in the active steering system,a four wheel active steering sliding mode controller based on multi-agent is proposed to overcome the unknown parameter fluctuations of the vehicle and the disturbance from the external environment.Through the cooperation of four wheels,the actual sideslip angle and yaw rate of the center of mass can track their ideal values in a limited time under different road adhesion conditions,Improve the active safety and handling stability of the entire vehicle during driving.(3)In the vehicle control system,a sliding mode observer for the center of mass sideslip angle is proposed based on the known yaw rate to address the issue of difficult acquisition of the center of mass sideslip angle,achieving estimation of the center of mass sideslip angle.We have built a hardware in the loop test bench for the controller and conducted experimental verification on the method proposed in this paper.