Electrically operated power steering system

An electrically operated power steering system on a motor vehicle having steerable road wheels, comprising:

• manual steering force generating means for generating a manual steering torque;
• an electric motor for generating an assistive torque to assist the manual steering torque generated by said manual steering force generating means;
• steering torque detecting means for detecting the manual steering torque generated by said manual steering force generating means and producing a manual steering torque signal indicative of the detected manual steering torque;
• steering angle detecting means for detecting a steering angle for the motor vehicle and producing a steering angle signal indicative of the detected steering angle;
• target steering torque signal generating means, operably coupled to said steering angle detecting means, for generating a target steering torque signal representing a target steering torque based on the steering angle signal produced by said steering angle detecting means;
• calculating means, operably coupled to said target steering torque signal generating means and said steering torque detecting means, for calculating the difference between said target steering torque signal and said manual steering torque signal;
• and
• motor drive signal generating means, operably coupled to said calculating means, for generating a motor drive signal to be supplied to said electric motor for driving said electric motor based on the difference between said target steering torque signal and said manual steering torque signal, wherein a direction for determining said target steering torque is the same as a direction of said detected steering angle.