Sensorless control of Electric Power Assisted Steering system

This paper deals with the sensorless control of Electric Power-Assisted Steering (EPAS) system with the permanent magnet synchronous motor (PMSM) using sliding mode techniques. Using steering wheel angle and motor currents measurements, two cascaded sliding mode observers with unknown inputs are designed. The whole observer generates the driver torque needed to determine the amount of the assistance and the other pieces of information needed to implement the controller. H-in nity sliding mode control is designed to generate the basic assist torque, improve damping characteristics of EPAS and attenuate the mismatched disturbances. Simulation results show the effectiveness of the proposed control.