Patent ID: 8219277

Claim:
An electric power steering apparatus comprising: a steering force assisting device that applies assisting force for assisting steering operation to a steering system using a motor as a driving source; a torque detector that detects a steering torque transmitted via a steering shaft; and a controller that controls the steering force assisting device on the basis of the steering torque, wherein the torque detector includes two sensor elements that respectively have inverse output characteristics from each other; and a failure detector that detects a failure of each sensor element, wherein the torque detector calculates the steering torque on the basis of output voltages of the two sensor elements, the output voltages being input as two independent sensor signals, when the total value of the two output voltages falls outside a predetermined range, the torque detector determines that a failure has occurred in at least one of the sensor elements, the torque detector determines if either one of the output voltages falls outside a predetermined output range, if the torque detector determines that both of the output voltages do not fall outside the predetermined output range, then the torque detector determines if either one of the output voltages has steeply varied over time to exceed a range caused by the steering operation, and the torque detector determines that a failure has occurred in the respective one of the sensor elements corresponding to either one of the output voltages determined to fall outside the predetermined output range or determined to steeply vary over time, and then the torque detector calculates a temporary torque on the basis of the other one of the output voltages.