Research On Electric Power Steering Control Strategy Of Automobile

With the development of the automotive industry,automotive electric power steering(EPS system)has become a key research object for researchers.The EPS system can adjust the steering assist according to parameters such as steering wheel torque and vehicle speed,improve the road feeling when the car is driving at high speed,and the portability during low-speed driving.At the same time,it also reduces the impact of uneven roads and the inside of the system on the steering system,and improves the car operation stability and safety.First of all,the structure and working principle of EPS system are elaborated in detail.The EPS is analyzed and the dynamic model of each EPS component is established,including the steering wheel model,sensor model,assist motor model and rack and pinion steering gear.The model laid the foundation for the analysis of control strategies.Secondly,the characteristics of linear,polygonal and curvilinear assisted characteristic curves are studied in this paper.Here,this article selects the linear power assist characteristic curve,sets the related parameters of the linear equation,and designs the linear assist force characteristic curve according to the driver steering characteristic.This article studies EPS control strategies and uses assist,return,and damping controls.The SMC control and PID control algorithms are used to assist the control.Through the comparison of simulation experiments,the power assistance characteristics of the two assisted control strategies are analyzed.For the steering wheel return operation there is a lack of positive and back positive overshoot phenomenon,this paper uses PID control algorithm to solve and verify the relevant experiments.In addition,in order to prevent the steering from being too light when driving at high speed,this paper uses the damping control method of reverse current.Then,use MATLAB/Simulink software to build the simulation model of EPS structure and control strategy.Then set the vehicle parameter settings,road environment,output,input parameters and simulation conditions in the CarSim software.Afterwards,after completing the joint simulation model of CarSim and Simulink,the experimental validation of steering portability,steering dynamics,backlash and damping control was performed.Finally,for the assisted control strategy and the positive control strategy adopted in this paper,the hardware-in-the-loop experimental platform is used to verify the research control strategy,including the transition to portable experiments,low-speed and high-speed recovery experiments.