Apparatus and method for detecting neutral steering angle of steering wheel system for vehicle

An apparatus and method for detecting a neutral steering angle of a steering wheel system for a vehicle through which the vehicle runs straight are disclosed in which when a neutral proximity signal (E3) is outputted which indicates that a steering angle of the steering wheel falls in a predetermined angular range placed in a proximity to the neutral steering angle, a deviation quantity (angle value) between the steering angle received from a steering angle sensor (1) at a time when the neutral proximity signal is outputted and neutral steering angle is derived, updates, and stored as a final value irrespective of on and off of a vehiclar ignition switch. In addition, when the neutral proximity steering angle is received at a first time when the ignition switch has been turned on, the neutral steering angle is reproduced from the steering angle at that time and the final value of the deviation quantity.