Control apparatus

A control apparatus controlling a motor of an electric power steering system including:

• an input shaft that is connected to a steering member configured to be turned by a driver;
• a column shaft that is connected to the input shaft at a position opposite to the steering member;
• a turning device that includes a rack and pinion mechanism converting a rotational motion of the column shaft into a reciprocating motion, and turns a wheel;
• and the motor that generates assist torque assisting turning of the steering member, the control apparatus comprising:
• a reliability computation portion that computes a reliability according to an abnormality detection state for at least one of
• a current sensor detecting an energization current to the motor,
• a torque sensor detecting a steering torque, and
• a rotational angle sensor detecting a rotational angle of the motor;
• a steering-shaft load estimation portion that estimates a steering shaft load using
• a current corresponding value corresponding to a detection value from the current sensor,
• a torque corresponding value corresponding to a detection value from the torque sensor, and
• a rotational angle corresponding value corresponding to a detection value from the rotational angle sensor;
• and
• a weight changing portion that changes a weighting of a corresponding value from among the current corresponding value, the torque corresponding value and the rotational angle corresponding value, according to the reliability computed by the reliability computation portion,
• wherein the corresponding value corresponds to one sensor having a detected abnormality from among the current sensor, the torque sensor and the rotational angle sensor.