A simulation study of the control algorithm for a ball screw type motor-driven power steering system

Abstract The power steering system for vehicles is becoming essential for supporting the driver's steering efforts, especially for manoeuvring in parking lots. Although hydraulic power steering has been widely used for years, it is not efficient enough. The problems associated with a hydraulic power steering system can be solved by using a motor-driven power steering (MDPS) system. In this study, a dynamic model and a control algorithm for a ball screw type MDPS system have been derived and analysed by using discrete modelling technology. To improve the comfort level while steering and power steering characteristics, an additional scheme is added to the conventional power boosting control algorithm. Through simulations, the effects of the control gain on the steering angle gain in the frequency domain were verified. The steering returnability and steering torque phase lag in on-centre handling tests were also verified.