Patent ID: 7565947
Filing Date: 2009-07-28
Classification: B60W,B62D

Abstract:
1. A method of detecting the presence or absence of an abnormality using a vehicular steering system having a steering mechanism for steering steerable road wheels of a vehicle in accordance with a steering wheel to be steered by a driver of said vehicle and an auxiliary steering angle superposition mechanism with an electrically controllable rotational member, said method comprising: detecting a steering angle of said steering wheel operated by said driver as a steering wheel angle; detecting an auxiliary steering angle to be superposed by said auxiliary steering angle superposition mechanism using an auxiliary steering angle detection section; detecting the traveling state of said vehicle; setting a transmission characteristic between said detected steering wheel angle and said detected steered angle of said steerable road wheels in accordance with the traveling state of said vehicle; calculating a target auxiliary steering angle to be superposed by said auxiliary steering angle superposition mechanism in accordance with said transmission characteristic; driving said auxiliary steering angle superposition mechanism so as to make said auxiliary steering angle detected by said auxiliary steering angle detection section coincide with said target auxiliary steering angle; and detecting the presence or absence of abnormality of said auxiliary steering angle detection section; wherein said auxiliary steering angle detection section includes: a rotation angle sensor that outputs sin θ and cos θ corresponding to a rotation angle of said rotational member as detection signals; a rotation angle calculation section that calculates the rotation angle of said rotational member based on said detection signals; a multi-revolution counting section that counts the number of revolutions of said rotational member based on said rotation angle; and an auxiliary steering angle calculation section that calculates said auxiliary steering angle based on said rotation angle and said number of revolutions; wherein the presence or absence of abnormality of said auxiliary steering angle detection section is detected by monitoring said detection signals.