Provided is an electric assisted power steering apparatus having a structure able to disconnect a worm shaft from any malfunctioning motor of motors connected to opposite end portions of the worm shaft, thereby preventing the worm shaft from rotating heavily or failing to rotate. Even in the case in which the worm shaft is disconnected from the malfunctioning motor, a target rotation speed of the properly-operating motor is increased to prevent sudden changes in auxiliary torque occurring on a steering shaft, thereby promoting the safety of a driver. Torque required for the worm shaft is distributed to the two motors, thereby increasing the rotation speeds of the motors and reducing the size and fabrication costs of the motors.

A motor control circuit for an electric motor of an electric power assisted steering system comprises a switching circuit comprising a plurality of electrical switches, a current demand signal generator which converts the torque demand signal into a current demands signal; and a fault mode motor current controller that is responsive to an error signal that represents the difference between the current demand signal and the actual current flowing in the motor and is operable in the event of a fault where one phase is open-circuit to drive the remaining two phases as a single combined phase by generating a single voltage demand signal that is representative of the voltage to be applied across the combined phases, the voltage signal being in turn fed into a drive circuit for the switches that generates pulse width modulated switching signals for the switching circuit required to apply the voltage across the combined phases.

A motor vehicle for piloted driving including a front axle steering system and a rear axle steering system. In the active, trouble-free driving state with a piloted driving, the driving task for steering the front axle is performed by a front axle steering control which automatically controls the front axle steering system. A failure of the automatic front axle steering control is automatically recognized with a failure recognition device and the vehicle steering is taken over by the rear axle steering system. The motor vehicle is equipped with a device for controlled wheel-selective brake intervention. In case of a failure of the automatic front axle steering control, this device is controlled in such a way that an automatic centering of the front axle steering system is performed by wheel-selective braking interventions.

A motor control circuit for an electric motor of an electric power assisted steering system of the kind in which a measurement of torque carried by a part of the steering system is used to produce a torque demand signal indicative of a torque to be applied to the steering system by the motor. The motor control circuit includes a current controller is responsive to an error signal that represents the difference between a current demand signal and an actual current signal, and a noise reduction circuit adapted to identify an operating condition of the system in which the motor is stationary or rotating at a very low speed, and in the event that the operating condition is identified the noise reduction circuit is adapted to reduce the response of the controller to variations in the error signal.

A first microcomputer is configured to identify the cause (a content of the abnormality) of a communication abnormality based on a combination of whether communication through a first communication line is established, whether communication through a second communication line is established, and whether a second clock is normal. Specifically, the first microcomputer separately determines whether the communication abnormality between the first microcomputer and a second microcomputer is simply due to an abnormality in the first communication line and the second communication line, or due to stop of a function of the second microcomputer. The second microcomputer is configured to identify the cause of the communication abnormality based on a combination of whether the communication through the first communication line is established, whether the communication through the second communication line is established, and whether a first clock is normal.

A controller for a steering device includes an electronic control unit configured to control the steering device. The electronic control unit is configured to acquire an action force and to calculate a basic reaction force based on the acquired action force. The action force includes at least two of axial forces of a plurality of types and a tire force. The axial forces of a plurality of types are applied to a turning shaft that is connected to turning wheels. The tire force is applied to the turning wheels. The electronic control unit is configured to, when one predetermined force of the acquired action force is abnormal, calculate the basic reaction force such that a contribution proportion of the predetermined force to the basic reaction force is lower than a contribution proportion when the predetermined force is not abnormal.

One of objects of the present invention is to provide a power steering apparatus capable of improving accuracy of abnormality detection. A power steering apparatus includes a steering mechanism configured to transmit a rotation of a steering wheel to a turning target wheel, an electric motor configured to provide a steering force to the steering mechanism, a torque sensor configured to detect a steering torque generated on the steering mechanism, and a control unit configured to calculate, based on the steering torque, an instruction signal for controlling driving of the electric motor and output the instruction signal to the electric motor. The control unit includes a steering direction signal reception portion configured to receive a steering direction signal indicating a rotational direction of the steering wheel, and an abnormality detection circuit configured to carry out detection of an abnormality in the power steering apparatus based on a change in the steering torque in a predetermined region including a region in which the steering direction signal is switched.

Provided is an electric power steering device capable of continuing control while ensuring a satisfactory level of a steering feeling of a driver at a time of occurrence of failure of one motor winding set. A control part is configured to detect a failure of each component of the electric power steering device, and when control is continued with field-weakening control by a normal motor winding and an inverter circuit depending on the detected failure, restrict a d-axis current based on a torque ripple that occurs in a steering wheel of a vehicle with respect to the field-weakening control of a state in which the failure has not occurred.

A motor control unit that is connected to a motor release switch which includes FETs and is disposed between an inverter and a motor, including: a control section to detect an assist state of the inverter, to turn-ON or turn-OFF a control of the inverter based on a detection result and to detect whether abnormality is existed or not; a motor rotational speed detecting section to detect a motor rotational speed; an energy calculating section to calculate an energy based on the motor rotational speed; a judging section to turn-OFF all of the FETs of the motor release switch when the energy is within an area of safety operation; and a state detecting section to detect whether abnormality is existed or not based on information from an abnormality detecting section that detects abnormality of the sensors and the inverter, wherein the control section turns-ON the control of the inverter when the state detecting section does not detect abnormality and turns-OFF the control of the inverter when the state detecting section detects abnormality.

Provided are a motor driving control apparatus and a steering system. The motor driving control apparatus includes an inverter circuit configured to supply a motor driving power to a motor for steering assist, a motor control circuit configured to control operation of the inverter circuit according to whether a control power is input, and a switch circuit configured to control whether to input the control power to the motor control circuit in response to a control signal. When a failure occurs inside or outside the steering system, the apparatus and steering system can immediately stop motor driving for steering assist and thereby prevent a vehicle accident.