Research On EPS Calibration Method Based On Steering Dynamics

Electric power steering(EPS)is a power steering system that directly relies on the motor to provide auxiliary torque.Compared to traditional hydraulic power steering(HPS),it has more energy saving and environmental protection advantages.Therefore,electric power steering has become the current automobile.One of the important signs of advanced products and electrification is being widely popularized in the global automotive industry.The main reason for the difficulty of the current popularization of electric power steering is that it is easier to calibrate the power-assisted characteristics,but it is difficult to calibrate the driving feel.It is necessary to conduct field tests on the actual car based on the experience of the car assessor.The amount of engineering is large and requires various Manufacturers have accumulated for a long time,so their prices are still high,and they are currently popularized in high-end models.Classic EPS controllers usually include a basic booster table and other dynamic correction methods,and the basic booster table mainly relies on the experience of engineers to obtain a large number of real vehicle field tests through tuning in the later stages of product development.After investigation,it was found that the basic booster table should include complicated non-linear factors such as someone's driving intention and vehicle dynamics,but there is no detailed theoretical analysis of this in the published literature.Aiming at this problem,this article attempts to explore the theoretical relationship between the basic booster table,driving intention,and dynamic characteristics,analyzes the theoretical mechanism of the basic booster table,and proposes to use the lateral movement trend and steering angle of the car as intermediate variables.The basic booster table is decomposed into three parts: driving style setting,chassis dynamic steady-state characteristics and steering dynamic steady-state characteristics,and applied to engineering calibration,which greatly reduces the difficulty of calibration.The main research contents of this article are as follows:First,modeling research on electric power steering system.First,the classic EPS control strategy is studied,and the basic booster table model and the dynamic correction model are established.Second,the steering system dynamics is analyzed and studied,and the steering system model is established.The model is used to accurately describe and express the model,and to assist in the subsequent steady state.The mechanism analysis of the characteristics provides a basis for research.Second,the mechanism of EPS basic booster.According to the theoretical relationship between the basic booster table and driving intention and dynamic characteristics,the theoretical mechanism of the basic booster table is analyzed.The steering angle and the lateral movement trend of the car are used as intermediate variables.The EPS basic booster table is decomposed into driving style settings.The three parts,chassis dynamic steady state characteristics and steering dynamic steady state characteristics,are expressed to provide a theoretical basis for the design of the EPS basic booster table and reduce the design difficulty.Third,research on the simulation calibration method of EPS basic booster.According to the researched theoretical method,the international standard test is used to measure the chassis dynamic steady-state characteristics and steering dynamic steady-state characteristics respectively to obtain the corresponding characteristics;on this basis,the driving style is set based on subjective and objective evaluations.Finally got the basic booster table.The driving simulator test verification shows that the method in this paper can maintain a good and consistent driving feeling in the full speed range,and has good adaptability to working conditions,which reduces the difficulty of designing and calibrating the EPS basic booster table during the development of automotive products.