Design, Development and Application of Test Bench for Electrically Controlled Steering Systems 2018-01-0702

This essay aims to develop an electrically controlled steering test bench and lay a solid foundation for the development of steering system. The first part mainly introduces the function, structure and working principle of the test bench. For the hardware system, it includes the steering system, fixture, sensors as well as a frameless disk motor for carrying out automatic motor input, and a dual linear motor system selected as the road resistance simulation actuator. As for the software, MATLAB/Simulink, CarSim, RTI and ControlDesk are used. Therefore, with the help of real-time simulation platform, researchers can not only build control strategy and dynamic model but also control the experiment and tune parameters in real-time. The second part of the essay aims to identify both electric and mechanical parameters of R-EPS system by carrying out tests on the proposed test bench. As parameters are successfully identified, the feasibility of the test bench is also verified. In the third part, control strategies of EPS are proposed. An improved assist curve, whose road feel intensity is continuous in every point is designed thoroughly, thus providing smooth steering feel to drivers. Returnability control strategy and damping control strategy are also designed in detail, so as to improve returnability as well as reduce overshoot and oscillation. Several joint simulations are carried out based on the identified parameters, and through comparison, the results show that the proposed strategies are effective and can greatly improve handling stability.