Design of a Simulation Environment for Testing the Control of Electric Power Steering Systems

The control of the driver’s steering torque of electromechanical power steering systems is state of the art. However, due to nonlinear characteristics and degrees of freedom of the plant which are unconsidered in the control design, the challenge still is the robust implementation of this control approach. Therefore, a new control approach was presented in previous papers that solves this robustness problems. In this paper, the control approach is analyzed in an augmented simulation environment. It is demonstrated that this control approach ensures a high robustness even when simulating critical driving situations. In addition, the control approach allows a nearly unconstrained design of the steering feel.

Based on a detailed nonlinear model of an electromechanical power steering, a reduced linearized model for the design of an optimal state space controller and an optimal state space observer is derived. Furthermore, a feeling system is presented. It determines the requested steering torque that the driver should feel at the steering wheel. This feeling system allows that the driver can experience an almost freely configurable steering feel. Moreover, a vehicle model with tire models and a driver model are added to the control system. Thus, real driving situations can be simulated. The results of the analysis of these real driving situations are presented in this paper. It is shown that the control approach ensures good dynamic characteristics and good robustness characteristics.