Research On Controller Desgin And Test System Of Automotive Electric Power Steering System

With the rapid development of the country and the continuous improvement of people’s living standards,people select the car to travel as preferred means of transportation,as time goes on,people have higher requirements for driving experience.The steering system has played a key role in the stability,comfort and safety of the car.At the same time,the steering system has changed from the initial purely mechanical steering to the later hydraulic power steering and electronically controlled hydraulic power steering,and then to the popular electric power steering system.The electric power steering system has been widely used for its advantages such as energy-saving,environmentally friendly,easy to control,available software adjustable,simple structure,small size,and easy to maintenance.Firstly,this article discusses the development history and current situation of the automobile electric power steering system(EPS),and then studies the EPS power-assisted mode and curve design principles,and designs a new type of EPS double-layer controller for a certain vehicle model.The upper controller adopts Fuzzy theoretical to design,a constant membership function is designed for each membership level of the target current to achieve accurate output of the target current of the booster motor and achieve a good boosting effect.The lower-level controller designs a sliding mode controller based on the exponential approach law to track the working current of the booster motor,Achieve the purpose of eliminate errors caused by external interference,and optimize the motor current follow ability.The results show the dynamic response speed of the sliding mode controller is more than 10 times that compare to the traditional PID control,and it is more stable.The EPS system is divided into four parts for dynamic analysis,a simulation model is established and verify the correctness of the model,and then co-simulated with the Car Sim car model that is closer to the actual vehicle to verify its boosting effect,which can satisfy the driver’s steering portability,And then simulate the test field experiment,input the step signal and pulse signal to the steering wheel,analyze the body roll angle,yaw rate and lateral acceleration of the whole vehicle,and verify the influence of the designed EPS controller on the stability of the whole vehicle.The results show that under the control of this controller,the car can maintain good stability and ride comfort under any driving conditions.Develop EPS performance test system using Labview software,the software needs to log in and verify to ensure the safety of data,and data can be collected and replayed after success.The collection interface display data waveforms using a friendly visual graphic interface,and there are status prompts and real-time data.The display is easy to use and connect.The computer is connected with USB3202 data acquisition to test performance on the automobile test bench named Changhe.The test signal is stable and high-precision,which can meet the performance test requirements of the industrial field.