Electric power steering system

An electric power steering system comprising:

• steering torque detecting means for detecting a steering torque of a steering shaft;
• an electric motor which generates an assist torque for assisting a driver's steering effort required for steering the vehicle and a counter-assist torque for increasing the driver's steering effort, the assist torque and the counter-assist torque being applied to a steering mechanism;
• and
• control means for outputting a drive command to the electric motor in accordance with the detected steering torque, the drive command being for causing the electric motor to generate the counter-assist torque when the detected steering torque is a transitional torque.

A method of operating an electric power steering system, comprising:

• detecting a steering torque of a steering shaft;
• generating an assist torque for assisting a driver's steering effort required for steering the vehicle and a counter-assist torque for increasing the driver's steering effort by using an electric motor, the assist torque and the counter-assist torque being applied to a steering mechanism;
• and
• outputting a drive command from a controller to the electric motor in accordance with the detected steering torque, the drive command being for causing the electric motor to generate the counter-assist torque when the detected steering torque is a transitional torque.