The steering force from the steering wheel is sent to the column shaft. The torque sensor measures the difference between the force applied to the column shaft and the resistance to turning the wheels due to road friction, and converts it to a voltage signal which is sent to the EPS control unit. Based on this signal, the EPS control unit controls the current to the EPS motor. The EPS motor rotates the worm gear which engaged to the worm wheel gear which is part of the column shaft. This becomes the assist force in the steering system.