Electric power steering system

An electric power steering system, comprising:

• a steering mechanism for converting a rotational movement of a steering wheel to a steering movement of a road wheel;
• a steering torque sensor for detecting a steering torque applied to the road wheel;
• an electric motor for providing an assisting force for causing the steering movement of the road wheel;
• and
• a control unit for providing a control variable for the electric motor;
• the control unit including
• a target control base value determining unit for determining a target control base value for the electric motor at least according to a steering torque applied to the steering wheel,
• a correction value determining unit that modifies the target control base value so as to determine a retuning force that urges the steering wheel toward a neutral position, and forwards the modified target control base value to a drive unit for the electric motor,
• wherein the correction value determining unit modifies the target control base value so as to cause the electric motor to produce a relatively large returning force when a rotational direction of the steering wheel agrees with a direction of the steering torque applied to the road wheel, and a relatively small returning force when a rotational direction of the steering wheel disagrees from a direction of the steering torque applied to the road wheel.