Enhancement of Steering Feel of Electric Power Assist Steering System Using Modeling Reference Control

This paper presents a torque overlay control algorithm to improve the steering feel of an electric power assist steering system. A feedback control strategy is employed in which the proposed control algorithm utilizes a reference model to generate a target steering feel to be tracked. The proposed torque overlay control algorithm consists of three main components: reference model, rack force estimator, and tracking controller. A dynamic electric power assist steering (EPAS) model, which takes estimated rack force from a rack force estimator as input, is used as a reference model to produce a target steering feel. A sliding mode controller is used as a tracking controller to control the system output to follow the reference signal. The performance of the proposed control system is evaluated through simulation, which shows that the proposed control system is effective in enhancing the steering feel of electric power assist steering.