Arc Welding Robot Control for False Contact Stop Suppression
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Solution Overview
Problem
Collaborative robots used in arc welding often experience unnecessary process stoppages due to erroneous contact detection of external forces, which are not safety-threatening but trigger the contact stop function.
Innovation Solution
A robot control device that includes an operation stop unit, an instruction unit, and a detection sensitivity adjustment unit, which decreases the sensitivity of external force detection after the start of the welding process to minimize false triggers during the initial stages of arc welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensitivity of external force detection is increased to improve safety monitoring, then the robot can detect actual contact forces more accurately, but the frequency of erroneous contact detection increases causing unnecessary process stoppages
Solution Approach 1:
The patent applies dynamics by making the detection threshold adjustable rather than fixed. The threshold is dynamically changed based on the welding state: a first threshold is used during welding execution, and a second threshold is used during standby periods. This dynamic adjustment allows the system to maintain high sensitivity during welding while reducing false detections during idle times, thereby resolving the contradiction between safety monitoring accuracy and process continuity.
Solution Approach 2:
The patent changes the detection parameter (threshold value) based on different operational phases. By switching between a first threshold value during welding execution and a second threshold value during standby periods, the system optimizes detection sensitivity to match the actual operational context. This parameter change strategy prevents erroneous stoppages while maintaining effective safety monitoring during critical welding operations.
2Reliability
If the contact stop function is activated to stop robot operation upon detecting external force, then safety is improved, but the welding process is interrupted by false stoppages during retry operation
Solution Approach 1:
The contact stop function is dynamically controlled by adjusting the detection threshold based on welding state. During retry operation and standby periods, the second threshold reduces false positive detections that would trigger unnecessary stoppages. During actual welding execution, the first threshold ensures safety protection is maintained. This dynamic control resolves the contradiction between safety protection and process interruption.
Solution Approach 2:
The system performs preliminary classification of external forces by comparing them against context-dependent thresholds before triggering the contact stop function. By preliminarily evaluating whether the detected force is genuine or erroneous based on the current welding state, the system avoids unnecessary process interruptions while maintaining safety protection when truly needed.
3Reliability
If the robot continuously monitors external force during welding, then safety is enhanced, but false detections during wire supply retry operation cause unnecessary stoppages
Solution Approach 1:
The monitoring sensitivity is dynamically adjusted based on the welding operational phase. During wire supply retry operation and standby periods, the second threshold reduces false detections that would disrupt operation smoothness. During active welding execution, the first threshold ensures continuous safety monitoring. This dynamic adjustment resolves the contradiction between safety monitoring and operation smoothness.
Solution Approach 2:
The system applies different detection characteristics to different operational phases. By using a second threshold specifically during standby and retry operations, and a first threshold during welding execution, the system tailors the monitoring quality to the local operational context. This local differentiation maintains safety monitoring effectiveness while ensuring smooth retry operations without false stoppages.
Data Source
AI summary
Provided is a robot control device that can suppress the stoppage of operations due to the detection of a contact error. The robot control device controls a robot that implements welding in association with contact with a to-be-welded object, said device comprising: an action stoppage unit that stops the action of the robot if detected that the robot has been subjected to an external force equal to or greater than a threshold; an instructing unit that instructs a welding power supply device to start welding; and a detection sensitivity adjustment unit that lowers the sensitivity at which as external force is detected at the action stoppage unit during a period of time from the point in time at which the instructing unit instructs the welding power supply device to start welding until a prescribed wait time has elapsed.