Patent ID: 8738229

Claim:
An electric power steering device, comprising: a steering force assist device, the steering force assist device having a motor as a drive source and applying to a steering system an assist force for assisting steering operation; a control device, wherein the control device controls the operation of the steering force assist device and computes a basic component of the assist force to be generated by the steering force assist device based on a detected steering torque; a determining device that determines whether a vehicle is traveling forward in a straight line; and a computing device that computes a compensation component for increasing the assist force based on an integration of the steering torque, wherein the control device superimposes the compensation component on the basic component when the determining device determines that the vehicle is traveling forward in a straight line, the computing device is configured to determine a steering torque determination value that changes in accordance with the magnitude of the steering torque, and to compute the compensation component based on an integration of the steering torque determination value, and the computing device is configured to determine the steering torque determination value by: setting the steering torque determination value to zero in a range where the absolute value of the steering torque is less than or equal to a predetermined threshold value, and computing the steering torque determination value such that, in a range where the absolute value of the steering torque is greater than the predetermined threshold value, the greater the absolute value of the steering torque, the greater the absolute value of the steering torque determination value becomes.