Control device and control method for internal combustion engine

1. A control device for an internal combustion engine, comprising:

a controller that controls a control object device based on an output value of a relative angle sensor configured to detect a relative angle of an output shaft of an actuator, and an output value of an absolute angle sensor configured to detect an absolute angle of a drive shaft coupled to the output shaft of the actuator via a speed reducer, wherein

the control device corrects an output value of the absolute angle sensor based on an absolute angle of the drive shaft that is obtained from an output value of the relative angle sensor using, as a reference point, an output value of the absolute angle sensor at start-up of the internal combustion engine, and an output value of the absolute angle sensor.

2. The control device for the internal combustion engine according to claim 1 , wherein

the control device corrects the output value of the absolute angle sensor based on a deviation between the absolute angle of the drive shaft that is obtained from the output value of the relative angle sensor using, as the reference point, the output value of the absolute angle sensor at the start-up of the internal combustion engine, and the output value of the absolute angle sensor.

3. The control device for the internal combustion engine according to claim 2 , wherein

the deviation is obtained within a control range of the control object device.

4. The control device for the internal combustion engine according to claim 2 , wherein

the deviation is obtained based on a first value that is obtained when the control object device is displaced from one to the other of the control range, and a second value that is obtained when the control object device is displaced from the other to the one of the control range.

5. The control device for the internal combustion engine according to claim 4 , wherein

the deviation is obtained by averaging the first value and the second value.

6. The control device for the internal combustion engine according to claim 2 , wherein

the deviation is obtained per reference angle of the drive shaft.

7. The control device for the internal combustion engine according to claim 2 , wherein

when the deviation is beyond a predetermined range, the actuator is diagnosed to be abnormal.

8. The control device for the internal combustion engine according to claim 1 , wherein

the control object device is a variable compression ratio mechanism that changes a volume of a combustion chamber of the internal combustion engine, thereby making a compression ratio variable.

9. The control device for the internal combustion engine according to claim 1 , further comprising a stopper mechanism that restricts rotation of the drive shaft at at least one of an upper limit and a lower limit of the control range of the control object device,

wherein the reference point is corrected based on an absolute angle detected by the absolute angle sensor in a state where the rotation of the drive shaft is restricted by the stopper mechanism.

10. A control method for an internal combustion engine, comprising:

controlling the internal combustion engine using a control device that controls a control object device based on an output value of a relative angle sensor configured to detect a relative angle of an output shaft of an actuator, and an output value of an absolute angle sensor configured to detect an absolute angle of a drive shaft coupled to the output shaft of the actuator via a speed reducer, wherein

the control device corrects an output value of the absolute angle sensor based on an absolute angle of the drive shaft that is obtained from an output value of the relative angle sensor using, as a reference point, an output value of the absolute angle sensor at start-up of the internal combustion engine, and an output value of the absolute angle sensor.