| 摘要 |
PROBLEM TO BE SOLVED: To provide a technology capable of alleviating mishandling of a steering wheel on a road of a low coefficient of friction μ and ensuring a sufficient assist force on a road of a high coefficient of friction μ even when a failure occurs in torque detection means.SOLUTION: An electric power steering system includes: an electric motor that applies an assist force to handling of a steering wheel of a vehicle; a torque sensor that detects a steering torque of the steering wheel; steering angle detection means that detects a steering angle which is a rotation angle of the steering wheel; a sensor failure detector 27 that detects a failure of the torque sensor; and a sensor failure-time current determiner 28 that, when the sensor failure detector 27 detects a failure, determines a basic assist force, which serves as a base of the assist force, on the basis of the steering angle detected by the steering angle detection means, and controls the electric motor so that the electric motor can provide the assist force whose basic assist force has been corrected according to the acceleration of the steering angle.SELECTED DRAWING: Figure 3 |
