Power assisted steering systems provide a gear reduction of approximately 25:1 between a steering wheel and a steering mechanism and approximately 625:1 between an electric motor and a steering mechanism. The system is back-driveable from the steering mechanism. In one embodiment, the gear reduction is provided primarily by three planetary gear sets, with the remainder provided by axis transfer gearing. In another embodiment, the gear reduction is provided primarily by a cycloidal gear set, with the remainder provided by axis transfer gearing.

A drive force control system to increase a yaw rate greater than the yaw rate achieved by rotating a steering wheel to a maximum angle. A target yaw rate is calculated based on a steering angle of the steering wheel. A first predetermined torque and a second predetermined torque are calculated based on a difference between the target yaw rate and an actual yaw rate. When the steering angle of the steering wheel exceeds a first predetermined angle, a first correction torque to correct the first predetermined torque and a second correction torque to correct the second predetermined torque are calculated n accordance with the steering torque.

A stator core is a stack body of plural plates. Each plate includes an annular back yoke part, plural top-connected tooth parts, plural top-separated tooth parts, plural magnetic path parts and plural top open parts. The top-connected tooth part and the top-separated tooth part protrude from the back yoke part in a radial direction. The top magnetic path part connects top ends of two top-connected tooth parts. The top open part is open to a rotor side at both sides of the top end of the top-separated tooth part. The stator core includes a back yoke, plural teeth, plural partially-connected parts and plural open parts. Each partially-connected part is formed of plural top magnetic path parts and top open parts, which extend in an axial direction. Each open part is formed of only the plural top open parts, which extend continuously in the axial direction.

A motor controller for driving an interior permanent magnet (IPM) motor has a current feedback control unit that calculates a q-axis current restriction value based on a dq-axis voltage instruction value and a dq-axis current detection value, so that a power source current flowing in an inverter circuit is controlled to be equal to or lower than a target power source current. Provided that a torque current proportional to an output torque of the motor is defined as a torque current, a torque current converter converts the q-axis current restriction value to a torque current restriction value by using a d-axis current detection value. A torque current instruction value restrictor restricts a torque current instruction value with the torque current restriction value. A dq-axis current converter converts a post-restriction torque current instruction value to a d-axis current instruction value and a q-axis current restriction value.

Assist torque or reaction force torque with little unnatural feeling to a driver is applied. An ECU includes: a control amount calculation section that calculates a control amount for controlling magnitude of the assist torque or the reaction force torque with reference to steering torque applied to a steering member; and a control amount correction section that corrects the control amount calculated by the control amount calculation section with reference to a lateral G of a vehicle body, a steering angle of the steering member, and a steering angle speed of the steering member.

The present invention relates to a helical toothed belt including: a back portion in which a tension member is buried; and a plurality of tooth portions, in which: the plurality of tooth portions have a tooth pitch of 2 mm or more and less than 4 mm, in a case where the tooth pitch of the plurality of tooth portions is 2 mm or more and less than 3 mm, the back portion has a thickness of 0.4 mm or more and 1.2 mm or less, in a case where the tooth pitch of the plurality of tooth portions is 3 mm or more and less than 4 mm, the thickness of the back portion is 0.6 mm or more and 1.8 mm or less; and the tension member is a twisted cord including a high-strength glass fiber or a carbon fiber.

A steering control device that can more appropriately transmit a road-surface reaction force to a steering wheel is provided. The steering control device feedback controls a steering angle to a target steering angle that is a target value of the steering angle. The steering control device includes an estimated axial force computation circuit that computes an estimated axial force so as to reflect a road-surface reaction force in a reaction force generated by a reaction force actuator. The estimated axial force computation circuit computes the estimated axial force by causing a friction compensation amount computation circuit and an efficiency compensation gain computation circuit to compensate an initial estimated axial force computed by an initial estimated axial force computation circuit.

A drive force control system to increase a yaw rate greater than the yaw rate achieved by rotating a steering wheel to a maximum angle. A target yaw rate is calculated based on a steering angle of the steering wheel. A first predetermined torque and a second predetermined torque are calculated based on a difference between the target yaw rate and an actual yaw rate. When the steering angle of the steering wheel exceeds a first predetermined angle, a first correction torque to correct the first predetermined torque and a second correction torque to correct the second predetermined torque are calculated in accordance with the steering torque.

A steering system in a vehicle includes a plurality of subsystems provided with a control unit. The control unit includes a storage unit storing steer angle information regarding a steer angle of one of a steering mechanism and a steered mechanism when the steering mechanism or the steered mechanism stops, an abnormality determiner determining abnormality of the motor rotation detection value and the detection circuit in the plurality of subsystems at a start time of a motor based on a comparison of at least two parameters, and a steer angle calculator calculating the steer angle based on the parameters having been determined by the abnormality determiner as not abnormal.

A motor control device is provided. In this motor control device, a first switching circuit group and a second switching circuit respectively provided between first and second microcomputers and first and second power converters receive drive signals generated by the microcomputers included in the own system and other drive signals generated by a microcomputer other than the microcomputers of the own system, select the own drive signal or the other drive signal according to selection signal from the microcomputers of the own system, and output the selected drive signal to the power converter of the own system. The first and second microcomputers output the selection signals to the switching circuit groups of the own system so as to select the own drive signal when the microcomputers are operating normally, and output the selection signal so as to select the other drive signal when a monitoring circuit of the system detects an faulty in the microcomputers.