Research On Torque Feedback Of Steering System Based On Driving Simulator

Steering system is one of the important parts of the vehicle,and its performance directly affects the handling and stability of the vehicle.The steering system can provide the driver with road feeling feedback,which is convenient for the driver to master the contact information between the current vehicle tire and the road surface and make correct steering operation in time.The torque feedback of the steering system is the most important part of the road feeling,which is mainly reflected in the hand feeling of the steering wheel.There are many factors affecting the feedback torque of steering system,among which system friction and power assistance are the most important factors.At present,in most steering system dynamics models and dynamics simulation software,friction is ignored or simply set as a fixed value,and the power assistance adopts the way of looking up the table,so the expression of these two key links is not accurate.Therefore,this paper studies and analyzes the dynamic model of the steering system in detail,and establishes a more accurate feedback torque model to calculate the steering wheel torque.With the rapid development of computer and virtual reality technology,driving simulator technology is more mature and more applied to the research and development of automobile technology.The driving simulator realizes the closed-loop research of "person-vehicle-road",considers the subjective factors of people,and can get more ideal research results.Combined with the high-precision modeling research project of the steering system of the research group,this paper studies the torque feedback of the steering system based on the driving simulator.The main work contents are as follows:（1）Dynamic analysis and research of steering system.Taking the electric power steering system as the research object,its composition,working principle and classification are introduced.Simplifying the mechanical structure of EPS system and establishing the dynamic equation can achieve high simulation accuracy,less parameters and easy to obtain through steering test.The dry friction model of force controlled damper is used to express the system friction,and the damping characteristics are expressed by the velocity difference at both ends of the damper,which can show the influence of velocity on friction,and the calculation results are more accurate.The steering assist control model including assist,alignment and damping control is designed,which can well represent the assist characteristics of EPS system.The Bogie Test and parameter identification are carried out,and the parameter information required by the model is obtained.（2）Vehicle model construction and joint simulation scheme design.VICarRealTime software is used to build the whole vehicle model and briefly describe each subsystem,with emphasis on the basic steering system model and advanced steering system model of the software itself.Simulink is used to build the dynamic model of external steering system,and the joint simulation scheme with the whole vehicle model is designed.（3）Model validation and simulator application.The handling and stability test of the real vehicle is carried out,and the simulation under the same working conditions is carried out.The simulation results are compared with the test data to verify the accuracy of the steering system model in the state of no assistance and with assistance respectively.The results show that the calculation results of the dynamic model of the external steering system are more accurate than the basic steering system model of the software itself,simpler than the advanced steering system model of the software itself,and can achieve the ideal simulation effect.After that,the model is connected to the desktop driving simulator to get the feedback of the steering wheel force feeling close to the actual vehicle.（4）Research on influencing factors of subjective evaluation sense of force based on driving simulator.According to the subjective evaluation content of handling and stability,the evaluation items and indexes related to the torque feedback of steering system are selected.Design subjective evaluation test items and determine the corresponding scoring method.Some factors that have great influence on the feedback torque of the steering system are selected,and the four factor and three-level orthogonal test is carried out by using the orthogonal test method,and the subjective score is given.The range method is used to analyze the test results,the influence degree of each factor on each evaluation index is obtained,and the influence reasons are analyzed.