Controller for electric motor

• US 20070205738A1
• Filed: 01/30/2007
• Published: 09/06/2007
• Est. Priority Date: 01/31/2006
• Status: Active Grant

• Current Assignee: Fanuc Ltd (Fanuc Corporation)
• Original Assignee: Fanuc Ltd (Fanuc Corporation)
• Inventors: Iwashita, Yasusuke, Maeda, Kazuomi, Toyozawa, Yukio
• Granted Patent: US 7,479,750 B2
• Time in Patent Office: Days
• US Class Current: 318/568.100
• 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 2219/41036 Position error in memory, lookup table for correction actual position
• CPC Class Codes: G05B 2219/41059 Play in gear, screw backlash, lost motion
• CPC Class Codes: G05B 2219/41077 Self tuning, test run, detect, compute optimal backlash, deformation compensation

Abstract

A controller including a learning control unit for determining learning data based on a positional deviation between a target-position command commanding superimposed-type motion including repetitive motion and a positional fed-back variable obtained from an output portion of an electric motor; and an operation control section for controlling the electric motor based on a corrected positional deviation. The learning control unit includes a first learning section for periodically determining, based on the positional deviation, and storing, first learning data according to a first learning period; a learning-data correcting section for correcting the first learning data to eliminate an influence of a local change included in the target-position command or the positional fed-back variable and periodically arising according to a period different from the first learning period; and a positional-deviation correcting section for correcting the positional deviation by using corrected learning data.

Claims

1. A controller comprising:

a learning control unit for determining learning data based on a positional deviation between a target-position command commanding superimposed-type motion including repetitive motion and a positional fed-back variable obtained from an output portion of an electric motor, storing the learning data, and correcting the positional deviation by using the learning data; and

an operation control section for controlling an operation of the electric motor based on a corrected positional deviation obtained in said learning control unit;

said learning control unit comprising;

a first learning section for determining, based on said positional deviation, and storing first learning data in a periodic manner according to a first learning period;

a learning-data correcting section for correcting said first learning data in a manner as to eliminate an influence of a local change included in at least one of said target-position command and said positional fed-back variable, said local change arising in a periodic manner according to a period different from said first learning period; and

a positional-deviation correcting section for correcting said positional deviation by using corrected learning data obtained by correcting said first learning data in said learning-data correcting section.

2. A controller as set forth in claim 1, wherein said learning-data correcting section comprises a second learning section for determining, based on said positional deviation, and storing second learning data different from said first learning data in a periodic manner according to a second learning period corresponding to said period of said local change, a correction calculating section for adding said second learning data to said first learning data, and an input switching section for allowing said positional deviation to be input to either one of said first learning section and said second learning section in a switchable manner.

3. A controller as set forth in claim 2, wherein said learning-data correcting section further comprises an output switching section for selectively intercepting an output of said second learning data from said second learning section.

4. A controller as set forth in claim 2, wherein said second learning period corresponds to a period of a disturbance arising in said positional fed-back variable.

5. A controller as set forth in claim 2, wherein said target-position command includes a first positional component repeated in accordance with a period corresponding to said first learning period and a second positional component repeated in accordance with a period corresponding to said second learning period;

and wherein said first learning section determines said first learning data based on a first positional deviation with regard to said first positional component and said second learning section determines said second learning data based on a composite positional deviation with regard to a composite position of said first positional component and said second positional component.

6. A controller as set forth in claim 1, wherein said target-position command includes a first positional component repeated in accordance with a period corresponding to said first learning period and a second positional component repeated in accordance with said period of said local change;

wherein said learning-data correcting section comprises a second positional-deviation estimating section for estimating a second positional deviation with regard to said second positional component, a first positional-deviation calculating section for calculating a first positional deviation with regard to said first positional component based on said second positional deviation and said positional deviation between said target-position command and said positional fed-back variable, and a correction calculating section for adding said second positional deviation to said first learning data; and

wherein said first learning section determines said first learning data based on said first positional deviation.

7. A controller as set forth in claim 6, wherein said learning-data correcting section further comprises a second learning section for determining, based on said second positional deviation, and storing a second learning data different from said first learning data in a periodic manner according to a second learning period corresponding to said period of said local change;

and wherein said correction calculating section adds said second learning data, in place of said second positional deviation, to said first learning data.

8. A controller as set forth in claim 6, wherein said target-position command is previously decomposed into said first positional component and said second positional component, said second positional component being input to said second positional-deviation estimating section.

9. A controller as set forth in claim 6, wherein said learning-data correcting section further comprises a second positional-component estimating section for estimating said second positional component based on said target-position command, said second positional-deviation estimating section estimating said second positional deviation based on said second positional component estimated in said second positional-component estimating section.

10. A controller as set forth in claim 6, wherein said second positional-deviation estimating section estimates said second positional deviation by referring to said second positional component included in said target-position command.