Servomotor control device, and servomotor control system

• US 10,152,042 B2
• Filed: 04/16/2018
• Issued: 12/11/2018
• Est. Priority Date: 04/26/2017
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: Shinoda, Shougo, Ikai, Satoshi
• Primary Examiner(s): Santana, Eduardo Colon
• Assistant Examiner(s): Agared, Gabriel
• Application Number:
  US15/953,861
• Publication Number:
  US 20180314228A1
• Time in Patent Office: 239 Days
• Field of Search: 318565
• CPC Class Codes: G05B 19/402 characterised by control arrangements for positioning, e.g. centring a tool relative to a hole in the workpiece, additional detection means to correct position G05B19/19 takes precedence
• CPC Class Codes: G05B 19/404 characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia G05B19/19, G05B19/41 take precedence
• CPC Class Codes: G05B 2219/37506 Correction of position error
• CPC Class Codes: G05B 2219/41166 Adaptive filter frequency as function of oscillation, rigidity, inertia load

Abstract

A servomotor control device includes: a servomotor, detection unit, driven body, connection mechanism, and motor control unit, in which the motor control unit includes: a force estimation section that estimates a drive force acting on the driven body at a connection part between the connection mechanism and the driven body; a correction amount generation section that generates a correction amount for correcting the position command value, based on the drive force estimated and a constant for correction; and a rigidity estimation section that gradually increases the constant for correction in a state suspending generation of the position command value, and estimates a magnitude of rigidity of the connection mechanism based on the constant for correction when a variation point occurs in behavior of rotation position information of the servomotor detected, drive force estimated, or correction amount generated.

Claims

1. A servomotor control device, comprising:

a servomotor;

a detection unit that detects a rotation position of the servomotor;

a driven body that is driven by the servomotor;

a connection mechanism that connects the servomotor and the driven body to transmit power of the servomotor to the driven body; and

a motor control unit that controls the servomotor based on a position command value,

wherein the motor control unit includes;

a force estimation section that estimates a drive force acting on the driven body at a connection part between the connection mechanism and the driven body;

a correction amount generation section that generates a correction amount for correcting the position command value, based on the drive force estimated by the force estimation section and a constant for correction; and

a rigidity estimation section that gradually increases the constant for correction of the correction amount generation section in a state suspending generation of the position command value, and estimates a magnitude of rigidity of the connection mechanism based on the constant for correction when a variation point occurs in behavior of rotation position information of the servomotor detected by the detection unit, drive force estimated by the force estimation section, or correction amount generated by the correction amount generation section.

2. The servomotor control device according to claim 1, wherein the rigidity estimation section defines a time when a local maximum appears in the behavior of the rotation position information of the servomotor detected by the detection unit, the drive force estimated by the force estimation section, or the correction amount generated by the correction amount generation section, as the variation point.

3. The servomotor control device according to claim 1, wherein the rigidity estimation section:

defines when a local maximum appears in the behavior of the rotation position information of the servomotor detected by the detection unit, the drive force estimated by the force estimation section, or the correction amount generated by the correction amount generation section, and a difference between the local maximum and a value during change in the constant for correction becomes at least a predetermined value, or a predetermined multiple of a difference between the value during change in the constant for correction and a convergence value after change in the constant for correction, as the variation point;

or

defines when a local maximum appears in the behavior of the rotation position information of the servomotor detected by the detection unit, drive force estimated by the force estimation section, or correction amount generated by the correction amount generation section, and a difference between the local maximum and a value during change in the constant for correction becomes at least a predetermined value, as the variation point.

4. The servomotor control device according to claim 1, wherein the behavior is a change with elapse of time.

5. The servomotor control device according to claim 1, wherein the motor control unit further includes a deterioration detection section that detects deterioration of the connection mechanism based on the magnitude of rigidity estimated by the rigidity estimation section.

6. The servomotor control device according to claim 5, wherein the deterioration detection section detects deterioration of the connection mechanism, when the magnitude of rigidity estimated by the rigidity estimation section has declined to no more than a predetermined first threshold.

7. The servomotor control device according to claim 1, wherein the motor control unit further includes:

a storage section that stores a plurality of magnitudes of rigidity estimated by the rigidity estimation section at every predetermined time interval or indefinite time interval, as rigidity data; and

a rigidity variation detection section that detects a change and variation in the rigidity of the connection mechanism, based on the rigidity data stored in the storage section.

8. The servomotor control device according to claim 1, wherein the motor control unit further includes:

a communication section that performs communication with another servomotor control device;

a storage section that stores rigidity data of its own device in which a plurality of magnitudes of rigidity of its own device estimated by the rigidity estimation section at every predetermined time interval or indefinite time interval and operating amounts are associated, and stores rigidity data of another device, in which a plurality of magnitudes of rigidity of another device at every predetermined time interval or indefinite time internal and operating amounts are associated, acquired by the communication section; and

an operating amount estimation section that derives a trend for change in rigidity based on the rigidity data of another device stored in the storage section, and estimates a remaining operable amount of the connection mechanism until the magnitude of rigidity declines to no more than a predetermined second threshold, based on the trend for change in rigidity thus derived, and the rigidity data of its own device stored in the storage section.

9. The servomotor control device according to claim 1, wherein the motor control unit further includes:

a storage section that stores rigidity data of its own device in which a plurality of magnitudes of rigidity of its own device estimated by the rigidity estimation section at every predetermined time interval or indefinite time interval and operating amounts are associated, and stores in advance trend data indicating a trend for change in rigidity of the connection mechanism; and

an operating amount estimation section that estimates a remaining operable amount of the connection mechanism until the magnitude of rigidity declines to no more than a predetermined second threshold, based on the trend for change in rigidity indicated by the trend data stored in the storage section, and the rigidity data of its own device stored in the storage section.

10. The servomotor control device according to claim 5, wherein the motor control unit further includes a notification section that notifies of information indicating the deterioration detected by the deterioration detection section.

11. The servomotor control device according to claim 7, wherein the motor control unit further includes a notification section that notifies of information indicating at least one of the change and variation in rigidity detected by the rigidity variation detection section.

12. The servomotor control device according to claim 8, wherein the motor control unit further includes a notification section that notifies information indicating the operable amount estimated by the operating amount estimation section.

13. The servomotor control device according to claim 10, wherein the notification section is a display device that displays information.

14. The servomotor control device according to claim 1, wherein the motor control unit further includes:

a communication section that sends a plurality of magnitudes of rigidity estimated by the rigidity estimation section at every predetermined time interval or indefinite time interval as rigidity data to an external storage section, and acquires the rigidity data stored in the external storage section; and

a rigidity variation detection section that detects a change and variation in rigidity of the connection mechanism, based on the rigidity data acquired by the communication section from the external storage section.

15. The servomotor control device according to claim 1, wherein the motor control unit further includes:

a communication section that sends rigidity data of its own device, in which a plurality of magnitudes of rigidity of its own device estimated by the rigidity estimation section at every predetermined time interval or indefinite time interval and operating amounts are associated, to an external storage section, and acquires the rigidity data of its own device and rigidity data of another device, in which a plurality of magnitudes of rigidity at every predetermined time interval or indefinite time interval and operating amounts are associated, stored in the external storage section; and

an operating amount estimation section that derives a trend for change in rigidity based on the rigidity data of another device acquired by the communication section from the external storage section, and estimates a remaining operable amount of the connection mechanism until the magnitude of rigidity declines to no more than a predetermined second threshold, based on the trend for change in rigidity thus derived and the rigidity data of its own device acquired by the communication section from the external storage section.

16. A servomotor control system comprising:

the servomotor control device according to claim 14; and

a server device that is connected to the servomotor control device and includes the external storage section.