Patent attributes
A steering angle calculation circuit of an ECU includes a neutral point calculation circuit, a correction amount calculation circuit, an adder, and an absolute angle calculation circuit. When started, the neutral point calculation circuit calculates a motor neutral point from a steering angle detected through a steering sensor and a motor rotation angle detected through a relative angle sensor. The correction amount calculation circuit calculates a correction angle that is a difference between a conversion value and an actual value of the motor rotation angle with respect to the steering angle. The conversion value is obtained by converting the steering angle in terms of the motor rotation angle by taking into account a theoretical specific stroke. The adder calculates a final motor neutral point by adding the correction angle calculated by the correction amount calculation circuit to the motor neutral point calculated by the neutral point calculation circuit.
