Robot Joint Gearbox Fault Diagnosis Using Torque Time-Series
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Solution Overview
Problem
Current robot systems lack the ability to accurately diagnose issues within the speed reduction mechanism, specifically identifying which speed-reduction elements are faulty, leading to inefficient maintenance and increased costs due to the need for replacing entire mechanisms rather than individual faulty components.
Innovation Solution
A robot system equipped with a determination unit that calculates time-series data on input and output torques, along with reduction ratios, to determine which speed-reduction elements are problematic, allowing for targeted maintenance by identifying issues at each element within the speed reduction mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque sensors and time-series data analysis are implemented to diagnose speed-reduction elements, then diagnostic precision is improved, but device complexity increases
Solution Approach 1:
The speed reduction mechanism is divided into multiple discrete speed-reduction elements (gears, shafts, bearings). Each element is individually diagnosed by analyzing torque fluctuations at specific frequency components corresponding to its rotational speed. This segmentation allows precise identification of faulty elements without requiring a complete system overhaul.
Solution Approach 2:
A determination unit acts as an intermediary between the torque sensor and the diagnostic conclusion. This unit processes raw torque data, performs frequency analysis, compares measured frequencies with calculated rotational frequencies of each speed-reduction element, and identifies faulty elements. The intermediary simplifies the diagnostic process by automating the complex analysis.
2Reliability
If entire speed reduction mechanisms are replaced instead of individual elements, then reliability is improved, but loss of substance increases
Solution Approach 1:
The faulty speed-reduction element is extracted and replaced individually from the otherwise functional speed reduction mechanism. The determination unit identifies the specific element (e.g., a particular gear or bearing) that is malfunctioning, allowing only that element to be removed and replaced while retaining all other healthy components. This reduces waste of functional parts.
Solution Approach 2:
Instead of discarding the entire speed reduction mechanism when one element fails, the healthy elements are recovered and retained in the system. Only the specific faulty element is discarded and replaced. This approach recovers the value of functional components and reduces material waste.
3Reliability
If entire speed reduction mechanisms are replaced instead of individual elements, then reliability is improved, but loss of time increases
Solution Approach 1:
The faulty speed-reduction element is extracted and replaced individually from the otherwise functional speed reduction mechanism. The determination unit identifies the specific element (e.g., a particular gear or bearing) that is malfunctioning, allowing only that element to be removed and replaced while retaining all other healthy components. This segmentation enables faster maintenance by avoiding unnecessary disassembly and reassembly of the entire mechanism.
Solution Approach 2:
The determination unit performs preliminary diagnosis by analyzing torque data to identify the faulty element before maintenance begins. This preliminary identification allows maintenance personnel to prepare the specific replacement part in advance and directly replace only the identified faulty element, significantly reducing on-site maintenance time compared to replacing entire mechanisms.
Data Source
AI summary
A robot system includes a robot that includes one or more joints, and a determination unit that is connected to the robot. The joints each include a motor, a speed reduction mechanism that reduces a speed of revolution of the motor; and a torque sensor capable of measuring an output torque of the speed reduction mechanism. The speed reduction mechanism includes a plurality of speed-reduction elements each of which reduces the speed of revolution of the motor at a predetermined reduction ratio. The determination unit calculates time-series data about an input torque to the speed reduction mechanism, and determines the speed reduction mechanism that has a problem, on the basis of time-series data about the number of revolutions of the motor, the calculated time-series data about the input torque, time-series data about the output torque measured by the torque sensor, and the reduction ratio of each of the speed-reduction elements.