Shift range control device

A shift range control device for switching a shift range by controlling driving of a motor, the shift range control device comprising:

• an angle calculation unit configured to acquire a motor rotation angle signal outputted from a motor rotation angle sensor, which detects a rotation position of the motor, and calculate a motor angle;
• a signal acquisition unit configured to acquire output shaft signals, which are output from an output shaft sensor for detecting a rotation position of an output shaft to which rotation of the motor is transmitted, values of the output shaft signals changing in steps in accordance with the rotation position of the output shaft;
• a learning unit configured to learn a position correction value, which is used to calculate a motor angle target value;
• a storage unit configured to store the position correction value;
• a target setting unit configured to set the motor angle target value according to a target shift range by using the position correction value;
• a drive control unit configured to control the driving of the motor such that the motor angle becomes the motor angle target value;
• an abnormality check unit configured to check whether the output shaft signals are available to be used, wherein
• the learning unit is configured to learn, as the position correction value, a normal state time correction value calculated based on at least one of a first reference angle and a second reference angle when at least one of the output shaft signals is available to be used at time of turning on of a start switch, the first reference angle is the motor angle at time when the output shaft signal changes in response to the rotation of the motor in a first direction, and the second reference angle is the motor angle at time when the output shaft signal changes in response to the rotation of the motor in a second direction opposite to the first direction;
• and
• the target setting unit is configured to set the motor angle target value by using the normal state time correction value stored in the storage unit during a period from a time point at which all of the output shaft signals are determined to be unavailable to be used until a time point at which the start switch is turned off;
• the output shaft is rotatable integrally with a rotation member which is formed with a plurality of valley sections, to which an engagement member is engaged according to a shift range, and ridge sections provided between the valley sections;
• the output shaft signal changes stepwise so as to have different values between before and after movement when the engagement member moves to the valley section which is adjacent to the engagement member;
• assuming that the first direction is a rotation direction of the rotation member when switching from a P-range to a range other than the P-range and the valley section at a P-range side of the ridge section is a P-range side valley section;
• the output shaft signals change values thereof at least at one position when the engagement member is at a predetermined position between a center of the P-range side valley section and a top of the ridge section;
• and
• the first reference angle is the motor angle at time of a change of the values of the output shaft signals when the engagement member moves from the center of the P-range side valley section toward the top of the ridge section.