Disturbance Torque Filter for Robot Failure Diagnosis
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Solution Overview
Problem
Conventional failure diagnosis methods for robots are prone to inaccurate diagnoses due to one-off abnormal values caused by sudden load changes during emergency shutdowns, leading to frequent false alarms and decreased accuracy.
Innovation Solution
A failure diagnosis device that calculates the change from a reference value for each disturbance torque measurement and excludes values with changes equal to or larger than a predetermined threshold, accumulating only stable data to improve diagnosis accuracy without requiring a costly production management system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed threshold is used to diagnose failures based on disturbance torque, then the diagnosis system is simple to implement, but the diagnosis accuracy deteriorates due to one-off abnormal values from emergency shutdowns
Solution Approach 1:
The system performs preliminary actions by detecting emergency shutdown events and identifying one-off abnormal values before they affect the failure diagnosis. By proactively removing these abnormal values from the disturbance torque data, the system ensures that subsequent diagnosis is based on accurate, representative data, thereby maintaining high diagnosis accuracy without requiring complex additional hardware
Solution Approach 2:
The invention extracts and removes one-off abnormal values from the disturbance torque measurements by comparing each value against a reference value and threshold. This extraction process isolates the harmful abnormal values caused by emergency shutdowns, allowing them to be excluded from the failure diagnosis calculation, thus improving measurement precision while keeping the system configuration relatively simple
2Reliability
If emergency stop information is acquired by cooperating with a production management system, then complete emergency stop information can be obtained, but large amounts of investments and maintenance costs are generated
Solution Approach 1:
The robot control device performs self-service by using its own internal resources (processor, memory, and existing disturbance torque measurement capabilities) to detect and handle emergency shutdown events. The system monitors its own operation status, identifies abnormal values, and performs corrections autonomously without requiring external production management systems, thereby achieving reliable emergency stop detection while minimizing system complexity and investment costs
Solution Approach 2:
The robot control device exhibits multi-functionality by combining its existing disturbance torque measurement function with emergency shutdown detection and abnormal value removal functions. This universal approach allows a single device to perform multiple tasks that would traditionally require separate systems, eliminating the need for additional production management system infrastructure while maintaining reliable emergency stop information acquisition
Data Source
AI summary
A failure diagnosis device applicable to a mechanical device provided with a motor as a source to drive a motion axis, and configured to acquire a moving position of the motion axis and a disturbance torque value applied to the motion axis every predetermined period, and to diagnose that a failure is occurring when the disturbance torque value is larger than a failure determination threshold, includes a disturbance torque selector configured to calculate a change from a reference value of each of the acquired disturbance torque values, and to accumulate the disturbance torque values except each disturbance torque value having the change from the reference value equal to or larger than a predetermined threshold, and a failure diagnosis unit configured to diagnose a failure of the mechanical device by using the disturbance torque values accumulated by the disturbance torque selector.