Steering device for vehicle

A vehicle steering device comprising:

• a steering mechanism that steers a wheel of a vehicle upon steering operation of a steering handle;
• an electric motor that is supplied with source power from an electric power source device and that generates assist force that assists in the steering operation of the steering handle;
• a steering torque detection unit that detects steering torque that a driver of the vehicle inputs to the steering handle;
• a control value computation unit that stores an assist characteristic that sets a motor control value that corresponds to the steering torque, and computes the motor control value based on the assist characteristic;
• a motor control unit that controls driving of the electric motor so that if the motor control value is larger, a larger assist force is generated, based on the motor control value computed by the control value computation unit;
• an electric power source abnormality detection unit that detects abnormality of source power supply capability of the electric power source device;
• an abnormality-time steering operation determination unit that determines whether or not a steering operation that satisfies a pre-set steering operation criterion condition has been started if the abnormality of the source power supply capability of the electric power source device has been detected by the electric power source abnormality detection unit;
• and
• a control value reduction unit that reduces the motor control value that corresponds to the steering torque by one step, if the abnormality-time steering operation determination unit determines that the steering operation that satisfies the steering operation criterion condition has been started,
• wherein the abnormality-time steering operation determination unit determines that the steering operation that satisfies the steering operation criterion condition has been started, if the steering torque detected by the steering torque detection unit is greater than a pre-set reference value.