Abnormality detection device and abnormality detection method
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Solution Overview
Problem
Existing abnormality detection devices for movable apparatuses, such as multi-axis robots, face challenges in accurately detecting abnormalities when the movement of joint shafts is small, as the change in disturbance torque may be insufficient to exceed a constant threshold, leading to inaccurate detection.
Innovation Solution
An abnormality detection device that includes a control unit capable of executing an integrated action by adding a necessary action to a predetermined routine operation, allowing for more precise abnormality detection by analyzing disturbance torque levels through a signal input from sensors, using a formula to calculate an abnormality level and determining abnormalities based on this analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant threshold is used for disturbance torque comparison, then the detection method is simple, but the abnormality detection accuracy deteriorates when movement is small
Solution Approach 1:
The patent applies dynamics by making the threshold adaptive rather than constant. The threshold is dynamically adjusted based on the relationship between joint shaft movement amount and disturbance torque. When movement is small, the threshold is lowered to maintain detection sensitivity, while when movement is large, the threshold is raised to avoid false positives. This dynamic adjustment resolves the contradiction between simple detection method and accurate abnormality detection.
Solution Approach 2:
The patent changes the threshold parameter based on operating conditions. Specifically, the threshold is modified according to the joint shaft movement amount - using a first threshold when movement exceeds a reference value and a second (lower) threshold when movement is below the reference value. This parameter change allows the system to maintain high detection accuracy across different operation scenarios while keeping the overall method relatively simple.
2Productivity
If the robot performs routine operations with small joint shaft movements, then the operational efficiency is maintained, but the disturbance torque change becomes insufficient for abnormality detection
Solution Approach 1:
The system dynamically adjusts the detection threshold based on the actual movement amount during routine operations. When the robot performs operations with small joint shaft movements, the threshold is automatically lowered to a second threshold value, ensuring that even small disturbance torque changes caused by abnormalities can be detected. This maintains both operational efficiency and detection reliability.
Solution Approach 2:
The patent performs preliminary classification of operation types based on joint shaft movement amounts before applying the appropriate threshold. By pre-establishing reference values and classification criteria, the system can quickly determine whether to use the first or second threshold without real-time complex calculations, thus maintaining operational efficiency while ensuring reliable abnormality detection for each operation type.
Data Source
AI summary
An abnormality detection device of detecting an abnormality of a robot which executes an operation such as welding on a target object, includes a control unit including a signal input unit to which a detection signal is input, the detection signal being obtained when a state of the robot is detected by a sensor, so that the control unit detects an abnormality of the robot in accordance with the detection signal. The control unit outputs a control signal to the robot so as to execute an integrated action in which a necessary action necessary for detecting an abnormality is added to a predetermined action in which the operation is not executed on the target object. The control unit detects the abnormality of the robot in accordance with the detection signal detected when the integrated action is executed.