1. A motor control device comprising:
a command generation unit (6) that outputs a drive command signal as a command to a drive unit (1) including a drive mechanism (2) driven by a motor (3);
a movement detection unit (5) that detects a position or speed of the drive unit (1) and outputs a movement detection signal;
a drive-current detection unit (7) that detects a drive current supplied to the motor (3) and outputs a drive-current detection value;
a control unit (4) that receives the drive command signal and the movement detection signal as inputs to generate a drive-force command signal, and supplies the drive current according to the drive-force command signal and the drive-current detection value;
a friction-characteristics estimation unit (8) that receives a drive force signal representing a drive force of the motor (3) and the movement detection signal as inputs to output a friction-characteristics estimate value;
a temperature-information acquisition unit (11) that acquires a temperature of the drive unit (1) or a temperature of a part whose temperature changes according to the temperature of the drive unit (1) and outputs a temperature information value;
a friction modeling unit (9) in which a reference friction model whose characteristics change according to the temperature of the drive unit (1) or the temperature of the part whose temperature changes according to the temperature of the drive unit (1) is set, which outputs reference friction characteristics based on the temperature information value; and
a friction-variation analysis unit (10) that outputs a friction variation value based on variation of the friction-characteristics estimate value with respect to the reference friction characteristics.
2. The motor control device as claimed in claim 1, wherein the friction-variation analysis
unit (10) outputs a friction variation value that represents a variation amount of the
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friction-characteristics estimate value with respect to the reference friction characteristics in percentage.
3. The motor control device as claimed in claim 1, comprising a temperature-friction model generation unit (15) that calculates the reference friction model based on the temperature information value and the friction-characteristics estimate value and sets the reference friction model to the friction modeling unit (9).
4. The motor control device as claimed in claim 1, wherein the temperature-information acquisition unit (11) is attached to the movement detection unit (5).
5. The motor control device as claimed in claim 1, wherein the temperature-information acquisition unit (11) is attached to the drive unit (1).
6. The motor control device as claimed in claim 1, wherein
the control unit (4a) includes a current control unit (42a),
the current control unit (42a) generates a drive-voltage command value based on the drive-force command signal and the drive-current detection value, and supplies the drive current calculated using the drive-voltage command value to the motor (3), and
the temperature-information acquisition unit (11a) estimates and outputs a temperature of the motor (3) based on the drive-voltage command value and the drive-current detection value without acquiring a temperature of the drive unit or a temperature of a part whose temperature changes according to the temperature of the drive unit.
7. The motor control device as claimed in claim 1, comprising:
a friction-force signal generation unit (18) that outputs a friction force signal based on the drive force signal and the movement detection signal; and
a reference friction-value generation unit (19) that outputs a reference friction value based on the reference friction characteristics and the movement detection signal, wherein
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the friction-variation analysis unit (10a) outputs the friction variation value based on a variation amount of a friction force signal with respect to the reference friction value, instead of the reference friction characteristics.
8. The motor control device as claimed in claim 1, comprising:
a plurality of temperature-friction storage units (12, 13, 14) that store a temperature value and friction characteristics at a specified temperature; and
a temperature-friction model generation unit (15) that calculates a reference friction model whose friction characteristics change according to a temperature change, by an approximate calculation based on the friction characteristics at a plurality of temperature values stored in the temperature-friction storage units, and sets the reference friction model to the friction modeling unit (9a).
9. The motor control device as claimed in claim 8, comprising a temperature–friction
automatic setting unit (16) that automatically sets the plurality of temperature-friction
storage units (12a, 13a, 14a) based on the temperature information value and the friction-
characteristics estimate value in a set period.
10. The motor control device as claimed in claim 8, wherein the temperature-friction model generation unit (15) calculates a reference friction model that passes through a point expressed by a temperature value and friction characteristics stored in at least one of the temperature-friction storage units, by an approximate calculation.
11. A motor control device comprising:
a command generation unit (6) that outputs a drive command signal as a command to a drive unit (1) including a drive mechanism (2) driven by a motor (3);
a movement detection unit (5) that detects a position or speed of the drive unit (1) and outputs a movement detection signal;
a drive-current detection unit (7) that detects a drive current supplied to the motor and outputs a drive-current detection value;
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a control unit (4) that receive the drive command signal and the movement detection signal as inputs to generate a drive-force command signal, and supplies the drive current according to the drive-force command signal and the drive-current detection value;
a friction-characteristics estimation unit (8) that receives a drive force signal representing a drive force of the motor (3) and the movement detection signal as inputs to output a friction-characteristics estimate value;
a continuous-operation counter unit (20) that outputs a continuous-operation counter value that monotonously increases at a time of a continuous operation;
a reference friction modeling unit (9b) in which a reference friction model whose characteristics change according to the continuous-operation counter value is set, which outputs reference friction characteristics based on the continuous-operation counter value; and
a friction-variation analysis unit (10) that outputs a friction variation value based on variation of the friction-characteristics estimate value with respect to the reference friction characteristics.
12. The motor control device as claimed in claim 11, wherein the continuous-operation counter unit (20) outputs a continuous-operation counter value that monotonously increases from start of a continuous operation in response to each passage of a unit time.
13. The motor control device as claimed in claim 11, wherein the continuous-operation counter unit (20) outputs a continuous-operation counter value that monotonously increases in response to a certain number of times of operations from start of a continuous operation.
14. The motor control device as claimed in claim 1, comprising a friction-abnormality diagnosis unit (21), wherein
the friction-abnormality diagnosis unit (21) compares the friction variation value with a preset normal value range, to determine whether the friction variation value is normal or abnormal, and outputs a friction-abnormality diagnosis signal.
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15. The motor control device as claimed in claim 1, comprising a friction-abnormality diagnosis unit (21a), wherein
the friction-abnormality diagnosis unit (21a), in which a normal value range defined by an upper limit and a lower limit is set, compares the friction variation value with the normal value range, and when the friction variation value exceeds the upper limit, outputs a friction-abnormality increase diagnosis signal, and when the friction variation value falls below the lower limit, outputs a friction-abnormality decrease diagnosis signal.
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