Research On Control Strategy And Simulation Of Automobile Electric Power Steering System

In recent years,with the rapid development of the automobile industry,the automobile has become an indispensable means of transport for the family,and its popularization rate has been significantly improved compared to previous years.The steering system of the automobile can provide better protection for the safe driving of the automobile as a driver's auxiliary steering system.As a new important automotive system,the main function of the EPS(Electric Power Steering)system is to help the driver to perform the corresponding operation of the assisted motor,so as to complete the steering.However,in this process,the characteristics of the ratio between the speed and the torque of the steering wheel,the real-time control of the motor controller,and the external environment during steering will all have a greater impact on the steering of the automobile.Therefore,it is necessary to carry out in-depth research on the three aspects of the entire EPS system.First of all,the basic principle and the basic structure of the EPS system are studied deeply.At the same time,the characteristics and process of the electric drive of the EPS system are analyzed in detail,including the analysis of the signal at the input,change and output.At the same time,the advantages and disadvantages of the old and current steering systems on the market are also understood.Aiming at the problems of the large phantom of the steering wheel and lack of consideration of driving conditions in the assist characteristics,the corresponding improvement design is carried out.Secondly,the assist characteristic of EPS system is improved.The assist characteristic is the control characteristic of the driver when turning the steering wheel.For example,the steering wheel is rotated at the same angle,and the different characteristics of the automobiles will lead to different steering angles.In the assist characteristic associated with the EPS system,the steering wheel torque and automobile speed are mainly considered,when the automobile is turning at low speed,the basic assist characteristic needs to meet the assist motor to provide greater power.When the automobile is turning at high speed,the assist motor provides less power.According to this rule,a assist characteristic curve of double break-point type is designed in this thesis.Its steering characteristic is proved by the simulation experiment platform.On this basis,the control performance of the steering motor is analyzed,and the motor controller is designed by using adaptive sliding mode algorithm.The design process of the controller is described in detail.Through the simulation experiment platform,the robustness and stability of the controller are tested under different automobile speed and steering wheel torque.Finally,the influence of the driving conditions on the steering of the automobile is considered during the normal driving process.The steering compensation control strategy of EPS system is put forward.At the same time,the design processes of high-speed collision avoidance,low-speed with full load,bumpy road and the compensation control strategy in the crosswind are described.The simulation platform is built by simulink software,and different control strategies are simulated under different driving conditions.The simulation results show that the compensation control strategy of the EPS system can effectively improve the driving safety and improve the driving strategy,which provides a theoretical basis for the new type of EPS system.