Life evaluating device and robot system

Patent metadata

Field	Value
Publication number	US-11045960-B2
Application number	US-201916444869-A
Country	US
Kind code	B2
Filing date	Jun 18, 2019
Priority date	Jul 10, 2018
Publication date	Jun 29, 2021
Grant date	Jun 29, 2021

Abstract

Provided is a life evaluating device that evaluates the life of a lubricant in a machine including a motor and a transmission mechanism that is lubricated by the lubricant and transmits power of the motor to a movable unit. The life evaluating device includes a motor-heat-value calculating unit that calculates a motor heat value on the basis of a current value of the motor, a frictional-heat-value calculating unit that calculates a frictional heat value in the transmission mechanism on the basis of rotating speed of the motor and a coefficient of friction of the transmission mechanism, a lubricant-temperature estimating unit that estimates temperature of the lubricant on the basis of the calculated frictional heat value and the calculated motor heat value, and a life estimating unit that estimates the life of the lubricant on the basis of the estimated temperature of the lubricant and information concerning impurities in the lubricant.

First claim

The invention claimed is:

1. A life evaluating device that evaluates a life of a lubricant in a machine including at least one motor and at least one transmission mechanism that is lubricated by the lubricant and transmits power of the at least one motor to a movable unit, the life evaluating device comprising:
a motor-heat-value calculating unit that calculates a motor heat value on the basis of a current value of the at least one motor;
a frictional-heat-value calculating unit that calculates a frictional heat value in the at least one transmission mechanism on the basis of rotating speed of the at least one motor and a coefficient of friction of the at least one transmission mechanism;
a lubricant-temperature estimating unit that estimates temperature of the lubricant on the basis of the frictional heat value calculated by the frictional-heat-value calculating unit and the motor heat value calculated by the motor-heat-value calculating unit; and
a life estimating unit that estimates the life of the lubricant on the basis of the temperature of the lubricant estimated by the lubricant-temperature estimating unit and information concerning impurities included in the lubricant;
wherein the life estimating unit estimates a life amount of the lubricant according to an equation described below:
Sg=m∫A k dt

Where, Sg represents a life use amount of the lubricant, A represents a constant set in advance, k is (T−T0)/Δ, when an estimated temperature T of the lubricant >T0 and is 0 when the estimated temperature T≤T0, Δ represents a difference from the temperature T0 at which the life use amount Sg is A times, and m represents a coefficient set according to an amount of the impurities included in the lubricant.

2. The life evaluating device according to claim 1 , wherein the motor-heat-value calculating unit calculates the motor heat value on the basis of the current value of the at least one motor and the rotating speed of the at least one motor.

3. The life evaluating device according to claim 1 , further comprising an air-cooling-heat-dissipation-amount calculating unit that calculates an air cooling heat dissipation amount on the basis of moving speed of the at least one transmission mechanism, wherein
the lubricant-temperature estimating unit estimates the temperature of the lubricant on the basis of the air cooling heat dissipation amount calculated by the air-cooling-heat-dissipation-amount calculating unit.

4. The life evaluating device according to claim 1 , further comprising a residual-life calculating unit that calculates a residual life on the basis of the life estimated by the life estimating unit.

5. The life evaluating device according to claim 1 , further comprising a replacement-date calculating unit that calculates an estimated replacement date on the basis of the life estimated by the life estimating unit.

6. The life evaluating device according to claim 1 , wherein the lubricant-temperature estimating unit estimates the temperature of the lubricant according to an equation described below:
T=T 0 +D 1 ×(Σ E i ×W 1i ) D 5 +D 2 ×(Σ F i ×W 2i ) D 6 +D 3 ×W 3 +D 4 ×W 4

Where, T represents an estimated temperature of the lubricant, T 0 represents a room temperature, i represents an axis affecting a target axis lubricant temperature including a target axis, D 1 , D 2 , D 3 , D 4 , D 5 , and D 6 represent coefficients identified by executing operations in various patterns in experiments in advance and acquiring data of temperatures of the lubricant, room temperatures, heat values, moving speeds of a reducer, and heat values of another heat generation source in the respective patterns, W 3 represents an air cooling heat dissipation amount, W 4 represents a heat value of the other heat generation source, E i represents a coefficient of the motor heat value W li , and F i represents a coefficient of the frictional heat value W 2i , and each of Ei and Fi represents a constant identified by executing operations in various patterns in experiments in advance and acquiring data of temperatures of the lubricant, room temperatures, heat values, moving speeds of the reducer, and heat values of the other heat generation source in the respective patterns or is a constant set in advance.

7. The life evaluating device according to claim 1 , wherein the lubricant-temperature estimating unit generates, according to machine learning using the frictional heat value and the motor heat value, a learned model for estimating temperature of the lubricant from the frictional heat value and the motor heat value.

8. The life evaluating device according to claim 1 , comprising a storing unit that stores a learned model generated by machine learning using the frictional heat value and the motor heat value, wherein
the lubricant-temperature estimating unit estimates the temperature of the lubricant using the learned model on the basis of the frictional heat value and the motor heat value.

9. The life evaluating device according to claim 7 , wherein the machine learning is supervised learning using teacher data in which the frictional heat value and the motor heat value are set as input data and a measured value of the temperature of the lubricant is set as a label and the input data and the label are associated with each other.

10. A robot system comprising:
a robot including the at least one motor comprising one or more motors, one or more movable units, and the at least one transmission mechanism comprising one or more transmission mechanisms that are lubricated by the lubricant and transmit power of the motors to the movable units;
a control device that controls the motors of the robot; and
the life evaluating device according to claim 1 .

Assignees

• Fanuc Corp

Inventors

• Guo Wei
• Nakagawa Hiroshi

Classifications

• B25J19/0062 Primary

  Lubrication means · CPC title

• F16N2260/18

  necessity of changing oil · CPC title

• B25J19/0095

  Means or methods for testing manipulators · CPC title

• F16N29/04

  enabling a warning to be given; enabling moving parts to be stopped · CPC title

• F16N2270/50

  Condition · CPC title