Control of an Electric Power Assisted Steering system using reference model

This paper presents a new control strategy of Electric Power Assisted Steering (EPAS) systems to ensure several control objectives. First, a reference model is employed to generate ideal motor angle that can guarantee the control objectives, assist torque generation, fast response to driver's torque command, vibration attenuation, supplying road information to the driver, improving steering wheel returnability and free control performance. Second, a sliding mode control law is used to track the desired motor angle. Finally, a sliding mode observer with unknown inputs and robust differentiators are designed to implement the reference model. Simulation results show that the proposed control structure can satisfy the desired performance.