Robot Joint Lubricant Life Evaluation Using Heat-Based Temperature Estimation
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Solution Overview
Problem
Existing life evaluating devices for lubricants in machines with motors and transmission mechanisms fail to accurately estimate lubricant temperature and life due to reliance on friction coefficients alone, neglecting motor heat values and air cooling effects.
Innovation Solution
A life evaluating device that calculates motor heat values based on motor current and speed, frictional heat values based on rotating speed and friction coefficients, and estimates lubricant temperature by combining these with air cooling heat dissipation, enabling accurate lubricant life evaluation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If lubricant temperature is estimated based only on friction coefficients, then the evaluation method is simple, but the temperature estimation accuracy is insufficient
Solution Approach 1:
The patent combines multiple heat source calculations (motor heat value from current, frictional heat value from coefficient of friction) with air cooling heat dissipation to comprehensively estimate lubricant temperature. This merging of multiple factors resolves the contradiction by maintaining reasonable complexity while significantly improving temperature estimation accuracy.
2Measurement precision
If motor heat value and air cooling effects are included in temperature estimation, then temperature estimation accuracy improves, but calculation complexity increases
Solution Approach 1:
The patent segments the temperature estimation into distinct calculation components: motor heat value calculation from current, frictional heat value calculation from coefficient of friction, and air cooling heat dissipation. This segmentation allows each component to be calculated independently and then combined, improving accuracy while managing complexity through modular calculation.
3Device complexity
If friction coefficient alone is used for lubricant life evaluation, then the evaluation process is simple, but the life evaluation accuracy is insufficient
Solution Approach 1:
The patent uses motor current as feedback to calculate motor heat value, which is then integrated with frictional heat value and air cooling effects to estimate lubricant temperature and predict remaining life. This feedback mechanism enables dynamic, accurate life evaluation that adapts to actual operating conditions while maintaining a systematic evaluation process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise estimation of lubricant temperature and life, accounting for motor heat and air cooling, thus providing reliable predictions for lubricant replacement times.
Implementation Method 1
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
Implementation Method 2
a frictional-heat-value calculating unit that calculates a frictional heat value in the transmission mechanism on the basis of rotating speed of the at least one motor and a coefficient of friction of the transmission mechanism
Implementation Method 3
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
Data Source
AI summary
A device for estimating a temperature of a lubricant in a transmission that transmits power from a motor to a robot joint includes a thermometer and a processor. The processor includes hardware configured to: receive, as input from the motor, a current value of the motor and calculate, as output, a motor heat value based thereon; receive, as input from the motor and the transmission, a rotating speed of the motor and a frictional torque of the transmission, and calculate, as output, a frictional heat value in the transmission based on the rotating speed of the motor and at least one of the frictional torque of the transmission and at least one coefficient of friction of the transmission; and receive, as input from the thermometer, the room temperature, the frictional heat value, and the motor heat value and estimate, as output, the estimated temperature of the lubricant based thereon.