Electric power steering apparatus

An electric power steering apparatus comprising:

• a steering member which is configured to be operated by a driver when turning a turning wheel of a vehicle;
• a steering torque detector for detecting a steering torque which is inputted by the driver to a steering shaft attached to the steering member based on torsion information of a torsion bar portion constituting at least a part of the steering shaft;
• a steering angle detector for detecting a steering angle of the steering member;
• a steering assist motor for applying a steering assist force to the steering member via the steering shaft in order to adjust the steering torque inputted by the driver;
• and
• a drive control unit for performing drive control of the steering assist motor based on at least the steering torque detected by the steering torque detector and the steering angle detected by the steering angle detector,
• wherein the steering angle detector is provided on a side of the steering member relative to a position where the steering torque detector is provided on the steering shaft
• wherein the electric power steering apparatus further comprises a steering information processing unit, which estimates a torsion angle of the steering shaft based on a detection result by the steering torque detector, and calculates a correction amount of the steering angle for compensating a torsion amount of the steering shaft based on the estimated torsion angle of the steering shaft, and then calculates a steering angle after a correction for compensating the torsion amount of the steering shaft based on the steering angle detected by the steering angle detector and the calculated correction amount of the steering angle, and
• wherein the drive control unit includes a steering reaction force characteristics storage unit for storing hysteresis characteristics related to a steering reaction force which is generated by driving the steering assist motor and is associated with a change of the steering angle after the correction in a case where the steering angle is increased or decreased by steering the steering member, and performs drive control of the steering assist motor based on the steering angle after the correction and the hysteresis characteristics stored in the steering reaction force characteristics storage unit.