# US 11,559,896 B2 · Failure prediction system

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- Number: US 11,559,896 B2
- Document ID: US11559896B2
- Status: Granted
- Kind: B2
- Application number: 16/908,450
- Filed: 2020-06-22
- Published: 2021-01-28
- Granted: 2023-01-24
- Earliest claimed: 2019-07-25
- Assignees: Fanuc Corporation
- Applicants: Fanuc Corporation
- Inventors: Takahiro Aoyagi; Norio Takei; Shinji Kurihara
- Web page: https://patentgrep.com/patent/US11559896B2

## CPC

- B25J 9/1674: {characterised by safety, monitoring, diagnostic}
- B25J 13/085: {Force or torque sensors (B25J13/082, B25J13/084 take precedence)}
- G05B 2219/42311: Store working torque profiles as function of time, position, compare with real torque
- B25J: MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES ({manipulators specially adapted for use in surgery A61B34/70; manipulators used in cleaning hollow articles B08B9/04}; manipulators associated with rolling mills B21B39/20; manipulators associated with forging machines B21J13/10; {manipulators associated with picking-up and placing mechanisms B23P19/007}; means for holding wheels or parts thereof B60B30/00; {vehicles with ground-engaging propulsion means, e.g. walking members B62D57/02, B62D57/032; devices for picking-up and depositing articles or materials between conveyors B65G47/90, B65G47/91; manipulators with gripping or holding means for transferring packages B65H67/065}; cranes B66C; {manipulators used in the protection or supervision of pipe-line installations F17D5/00; walking equipment adapted for nuclear steam-generators F22B37/006}; manipulators specially adapted for, or associated with, nuclear reactors G21C; {apparatus used for handling wafers during manufacture or treatment of semiconductor H10P72/50})
- G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G)

## Abstract

A failure prediction system includes: a processor, the processor being configured to: collect torque values of a drive axis of a robot that is operating in accordance with a given work program; derive an evaluation formula approximating a time change of the torque value which is most recent from among the collected torque values set a failure threshold that is the torque value at which it is determined that failure of the drive axis occurs, based on the evaluation formula and the time change of the torque value when the drive axis reached failure in the past; and calculate an estimated value for the torque value when a prediction time set in advance has elapsed in the evaluation formula, and determines whether failure of the drive axis is predicted within the prediction time according to comparison between the estimated value and the failure threshold.

## Claims

### Claim 1

A failure prediction system comprising:
a processor, the processor being configured to:
collect torque values of a drive axis of a robot that is operating in accordance with a given work program;
derive an evaluation formula approximating a variation of the torque value which is most recent from among the collected torque values;
set a failure threshold that is the torque value for determining occurrence of failure of the drive axis based on the evaluation formula and the variation of the torque value observed when the drive axis reached failure in the past; and
calculate, with the evaluation formula, an estimated torque value at a time when a prediction time set in advance has elapsed, and determines whether failure of the drive axis is predicted within the prediction time according to comparison between the estimated torque value and the failure threshold.

### Claim 2 (depends on 1)

The failure prediction system according to claim 1, wherein the processor defines, as the failure threshold, a value arrived at by multiplying a constant decided based on the time change of the torque value when the drive axis reached failure, by a value arrived at by substituting into the evaluation formula a time decided based on the time change of the torque value when the drive axis reached failure in the past.

### Claim 3 (depends on 1)

The failure prediction system according to claim 1, wherein the processor resets the torque values collected, during a change of the work program, and then newly collects the torque values.

### Claim 4 (depends on 1)

The failure prediction system according to claim 1, wherein the processor displays the torque value that is most recent on a graph, and in a case of the processor determining that failure of the drive axis is predicted, displays an indicator thereof.

### Claim 5 (depends on 4)

The failure prediction system according to claim 4, wherein the processor displays, on the graph, a line indicating a time of the torque value that is last when the processor determines that failure of the drive axis is predicted.