Abstract: A correction value calculating section 70 is provided with a pinion shaft torsion angle correction value calculating section 74 and a pinion shaft torsion angular velocity correction value calculating section 75 for calculating a correction value in consideration with the transmission characteristic of the steering assist torque from the electric motor 6 to the steerable vehicle wheel 9. Therefore, the electric motor 6 can generate the steering assist torque compensating for the influence by the transmission characteristic of the steering assist torque from the electric motor 6 to the steerable vehicle wheel 9 by correcting a target value defined by a detection value of the torque sensor 3 with the correction value.

Abstract: In an electric power steering system installed in a vehicle and designed to generate, by a motor, assist torque for assisting the driver's turning effort of the steering wheel, a self-aligning torque determiner determines a value of self aligning torque applied to the vehicle. A commanded-value generator determines a value of an assist ratio based on a predetermined relationship between a variable of the self aligning torque and a variable of the assist ratio. The assist ratio represents a ratio of share of torque by the motor for compensating the self aligning torque. The commanded-value generator generates, based on the self aligning torque and the value of the assist ratio, a commanded value for the assist torque. An assist torque determiner determines the assist torque based on the commanded value for the assist torque generated by the commanded-value generator.

Abstract: A control unit estimates reverse transfer torque transferred from tires to a steering wheel and calculates an assist gain based on the reverse transfer torque. The control unit calculates basic assist torque demand by multiplying torsion torque detected by a torque sensor by the assist gain. The control unit further calculates assist torque command by adding compensation for stabilization. Since the assist gain is determined based on the reverse transfer torque, actual assist torque is generated in accordance with the force transferred from the road surface. Thus, a driver can operate the steering wheel while feeling the force from the road surface.

Abstract: The control apparatus for an electric power steering system is designed to satisfy the first spec that a first relation characteristic between speed of the electric motor to generate steering assist force and the steering wheel torque is the same as a basic relation characteristic in which the electric motor is driven in accordance with a basic assist amount calculated on the basis of the measured steering torque not corrected by an assist compensation amount calculated depending on the operating state of the electric power steering system, and to satisfy the second spec that a second relation characteristic between speed of the electric motor and a road surface reaction force is such that speed of the electric motor is suppressed compared to a case where the electric motor is driven in accordance with the basic relation characteristic.

Abstract: In a steering system, a generator generates a first commanded value for assist torque, and a converter converts a second commanded value for the assist torque to a commanded current value. A current controller controls a drive current for driving a motor for generating the assist torque. A characteristic limiter is functionally interposed between a commanded-value generator and a converter, and limits, to a preset characteristic range, a characteristic of a functional downstream of the converter in the steering system. The functional downstream of the converter in the steering system includes a steering mechanism including the motor. The commanded-value generator inputs, to the characteristic limiter, the first commanded value. The characteristic limiter determines the second commanded current value for the assist torque based on the characteristic of the functional downstream and the first commanded value.

Abstract: In an electric power steering system installed in a vehicle and designed to generate, by a motor, assist torque for assisting the driver's turning effort of the steering wheel, a self-aligning torque determiner determines a value of self aligning torque applied to the vehicle. A commanded-value generator determines a value of an assist ratio based on a predetermined relationship between a variable of the self aligning torque and a variable of the assist ratio. The assist ratio represents a ratio of share of torque by the motor for compensating the self aligning torque. The commanded-value generator generates, based on the self aligning torque and the value of the assist ratio, a commanded value for the assist torque. An assist torque determiner determines the assist torque based on the commanded value for the assist torque generated by the commanded-value generator.

Abstract: In an electric power assisting system for a vehicle, a control unit receives an input shaft rotation angle detected by an input shaft rotation angle sensor and an output shaft rotation angle detected by an output shaft rotation angle sensor. The control unit controls rotation of a motor based on the detected two rotation angles. The control unit differently controls the rotation of the motor whether torque is applied from a steering wheel side or from a road surface side.

Abstract: A correction value calculating section 70 is provided with a pinion shaft torsion angle correction value calculating section 74 and a pinion shaft torsion angular velocity correction value calculating section 75 for calculating a correction value in consideration with the transmission characteristic of the steering assist torque from the electric motor 6 to the steerable vehicle wheel 9. Therefore, the electric motor 6 can generate the steering assist torque compensating for the influence by the transmission characteristic of the steering assist torque from the electric motor 6 to the steerable vehicle wheel 9 by correcting a target value defined by a detection value of the torque sensor 3 with the correction value.

Abstract: A control unit estimates reverse transfer torque transferred from tires to a steering wheel and calculates an assist gain based on the reverse transfer torque. The control unit calculates basic assist torque demand by multiplying torsion torque detected by a torque sensor by the assist gain. The control unit further calculates assist torque command by adding compensation for stabilization. Since the assist gain is determined based on the reverse transfer torque, actual assist torque is generated in accordance with the force transferred from the road surface. Thus, a driver can operate the steering wheel while feeling the force from the road surface.

Abstract: In an electric power assisting system for a vehicle, a control unit receives an input shaft rotation angle detected by an input shaft rotation angle sensor and an output shaft rotation angle detected by an output shaft rotation angle sensor. The control unit controls rotation of a motor based on the detected two rotation angles. The control unit differently controls the rotation of the motor whether torque is applied from a steering wheel side or from a road surface side.