Research On Control Strategy Of Active Steering System Based On Electric Power Steering System

With the advent of the fourth industrial revolution,the automotive industry is moving towards a new round of technological change with the trend of automation,intelligence and electrification,especially the automatic driving technology which has attracted much attention in recent years.The automatic driving vehicle mainly includes three parts: vehicle environment perception,bottom control execution and route decision making,and the steering control in the bottom control is the key to accomplish automatic driving.Based on the traditional electric power steering system(EPS)platform,this thesis launches the research on active steering control of automatic driving vehicle.The main contents of this thesis are as follows:First of all,the electric power steering system is classified,and the tubular electric power steering system(C-EPS)is selected as the actuator of automatic driving active steering,and the operating principle and key components of C-EPS in active steering are introduced.Then the dynamic analysis of C-EPS is carried out,at the basic of which this thesis build-up the mathematical model of active steering system.At the same time,considering that the active steering is provided by the motor torque to overcome the steering resistance and drive the front wheel to rotate,this thesis analyzes the steering resistance moment of the vehicle,and establishes the steering resistance moment model.Secondly,considering that the active steering system is a complex time-varying nonlinear system and the control effect of traditional control algorithm is poor,the overall design scheme of double closed-loop feedback control based on vehicle steering angle and motor current is developed.The position loop adopts the traditional PID controller;the current loop adopts the fuzzy adaptive PID controller,and designs the reasonable membership function and parameter adaptive rules for the active steering system,and then uses the Matlab toolbox to generate the fuzzy rule derivation table to complete the design of the controller.Then,based on the mathematical model and control algorithm framework of the active steering system,the simulation models of each module and controller of the steering system are built based on matlabgsimulink platform,and the simulation experiment platform is completed by integrating them.Finally,the simulation model is used as the carrier to carry out the active steering simulation experiment under various conditions to verify the effectiveness of the control algorithm.The experimental results show that,under the control of the double closedloop control feedback algorithm proposed in this paper,the steering system can not only keep following the target steering angle in real time and accurately,but also has good dynamic and static characteristics,and successfully completes the performance index of vehicle active steering.At the same time,compared with the traditional control algorithm,the control algorithm designed in this paper has better stability and robustness.