Patent attributes
When a braking operation amount is reduced, a stiffness value representing a ratio of variation in actual pressing force of a friction member to a variation in actual position of an electric motor are sequentially computed. The actual position when the stiffness value changes from being higher than or equal to a predetermined value to being lower than the predetermined value is stored as a candidate position. When a duration during which the stiffness value is lower than the predetermined value is shorter than a clearance corresponding value corresponding to a transmission member clearance in a state where the candidate position is stored, the candidate position is deleted. When the duration during which the stiffness value is lower than the predetermined value exceeds the clearance corresponding value, the stored candidate position is determined as a reference position at which the friction member and the rotary member begin contacting each other.
