Modeling and Simulation Research on the Electric Power Steering System for a Passenger Car

In order to expand the product design and development capabilities of Electric Power Steering (EPS) system, a passenger car’s simulation model integrated with EPS system model will be made. Some analytical investigation is conducted in this paper. Through simplifying the architecture model of EPS system, the mathematical equation expressions of steering wheel and column, worm gear reducer, rack and pinion, steer-wheels, brushed DC electrical motor, and ECU assistance and compensation laws will be described. A number of tests on the EPS full system and subsystems and components will be executed. The tests’ results will be used as the input parameters of the model, and then be used for model validations. After that, the EPS system model will be created. Since the most important part of control logic strategy is the top secret of steering assembly supplier and it could’t be provided to OEM in details or not even a black-box model directly. Accordingly a look-up tables controller model based on test datas will be developed in this paper. After the EPS model is validated, the chassis model integrated with it will be built, where the suspension characteristics are generated from K&C test rig. And the integrated chassis model will be validated by several typical handling maneuvers that focus on both objective and subjective evaluations. The following sensitivity analysis will find out the metrics influenced by which parameters of the controller to improve handling performance and driving feeling.