Speed Reducer Abnormality Diagnosis via Dynamic Threshold Adjustment
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Solution Overview
Problem
Existing methods for diagnosing speed reducer abnormalities in machine tools with tool changers struggle to accurately predict issues when tools are replaced, due to changes in inertia and disturbance torque, leading to false detection.
Innovation Solution
A machine tool system that includes a controller capable of estimating disturbance torque and adjusting thresholds based on tool mass arrangements, load waveforms, or total mass and centroid position patterns to accurately diagnose speed reducer abnormalities, even when tools are replaced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If disturbance torque is estimated by an observer based on torque command and speed feedback, then abnormality of speed reducer can be accurately diagnosed, but false detection occurs when tools are replaced due to changes in inertia
Solution Approach 1:
The threshold value is made dynamic rather than fixed. The controller dynamically adjusts the threshold value based on the actual tool mass arrangement detected in the tool magazine. This allows the diagnosis system to adapt to changing inertia conditions when tools are replaced, preventing false detection while maintaining accurate abnormality diagnosis.
Solution Approach 2:
The threshold parameter is changed according to the tool mass arrangement. Instead of using a constant threshold, the system calculates and applies different threshold values corresponding to different tool configurations. This parameter change enables the system to accommodate variations in moment of inertia caused by different tool placements.
2Device complexity
If a fixed threshold is used for abnormality diagnosis, then the diagnosis method is simple, but false detection occurs when tool mass arrangement changes
Solution Approach 1:
The threshold parameter is changed according to the tool mass arrangement. Instead of using a constant threshold, the system calculates and applies different threshold values corresponding to different tool configurations. This parameter change enables the system to accommodate variations in moment of inertia caused by different tool placements.
Solution Approach 2:
The system automatically detects the tool mass arrangement and self-adjusts the threshold value without requiring manual intervention. The controller reads the actual tool masses from storage, calculates the appropriate threshold, and applies it automatically, enabling the system to adapt to changing conditions on its own.
3Reliability
If tool mass arrangement is detected and threshold is dynamically adjusted, then false detection is prevented, but system complexity increases
Solution Approach 1:
The system automatically detects the tool mass arrangement and self-adjusts the threshold value without requiring manual intervention. The controller reads the actual tool masses from storage, calculates the appropriate threshold, and applies it automatically, enabling the system to adapt to changing conditions on its own.
Solution Approach 2:
The system implements feedback by continuously monitoring the tool mass arrangement and using this information to adjust the threshold value. The controller receives feedback about which tool is placed in which position, calculates the corresponding threshold from stored data, and applies it to the abnormality diagnosis process.
Data Source
AI summary
Tool mass arrangement patterns of masses of tools loaded onto tool holding parts of a tool magazine and thresholds, which are associated with the patterns and used to diagnose the abnormality of a speed reducer, are stored after associating the patterns with the thresholds. In addition, the masses of the tools loaded onto the respective tool holding parts are stored. Further, a tool mass arrangement pattern similar to a stored tool mass arrangement, among the stored tool mass arrangement patterns, is selected, and a threshold associated with the selected tool mass arrangement pattern is set as a threshold to be used to diagnose the abnormality of the speed reducer.