Study Of Vehicle Electric Power Steering System

An ideal steering system is not only easy to handle and more effective, but also provides the best steering feel to the driver. A conventional hydraulic power steering system uses power to supplement the force requirement to steer the wheel based on a fixed assist ratio of the driver's input. So a conventional hydraulic power steering system is capable of providing power-assisted steering, but it is difficult to supply the best steering feel. Electric power steering system (EPS) is more appropriate to realize an ideal steering than a conventional hydraulic power steering system, because it is easy to optimize the steering system characteristic by adjust parameters of the system's controller. This paper presents an improved PD control method, which is based on double fuzzy sets and auto-tuning techniques, and an "H-infinity control" method in order to obtain ideal EPS assist steering characteristics. Simulations and experiments of these control methods are carried out in this paper. The results show that the steering system with improved PD controller and H-infinity controller are easy to handle, more effective, robust and can supply the best steering feel. In the other word, the steering with improved PD controller and H-infinity controller are ideal steering systems.