Research On Modeling And Control Strategy Of Active Front Wheel Steering System

As an important part of automobile chassis system and an important link of human-vehicle interaction interface,steering system plays an important role in vehicle handling stability,comfort and safety.Automobile "intelligent","power" and "sharing" for Active control of vehicle Steering system and the development of Active safety technology put forward higher requirements,and Active Front Steering(AFS-Active Front Steering)technology can realize auto variable transmission ratio the driving stability of the operation,control and the trajectory tracking and automatic driving lane keeping control,gradually become the research focus in the automobile Steering system.Therefore,based on the EPS-Electric Power Steering system,the control strategy of the active front wheel Steering system is studied.The main work of this paper is as follows:(1)Proposed a new structure scheme of active front wheel steering system based on conventional EPS system,analyzed its structure and working principle,and conducted modeling and model verification tests for the steering system;The linear two degree of freedom(dof)lateral dynamics equation of the underactuated active front wheel steering system in fixed ground coordinate system is derived.(2)The control of the active front wheel steering system is divided into EPS control and AFS control.The control logic and control strategy of the active front wheel steering system are analyzed respectively.A constrained following control method for underactuated system with inequality constraints is proposed and applied to the trajectory tracking and lane keeping control strategy design of AFS system.(3)The corresponding simulation analysis and experimental verification were carried out on the designed control strategy.Through frequency domain and time domain simulation,the effectiveness of the stability control strategy under the EPS basic power mode is analyzed.Of AFS system through MATLAB/Simulink platform,the control strategy has carried on the simulation analysis,the results show that the proposed including inequality constraints of the underactuated system constraints following control method can achieve effective active front wheel steering system of trajectory tracking and lane keeping control target,improve the car's active steering and active safety performance.