Robot Welding Start Control With Dual External Force Thresholds
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Solution Overview
Problem
Existing robot welding systems face issues where setting a high external force detection threshold for safety can allow minor forces during welding initiation, leading to potential adverse effects on the robot and welding process due to continuous external forces, risking incorrect emergency stops.
Innovation Solution
A robot control device with separate thresholds for stopping the robot and welding wire feed, allowing controlled initiation of welding by independently managing external forces, and including a restart mechanism to resume welding if initiation fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the external force detection threshold is increased to prevent false emergency stops during welding initiation, then the reliability of safety control is improved, but the robot and welding torch may be adversely affected by continuous external forces acting during start of welding
Solution Approach 1:
The patent segments the external force threshold into two distinct thresholds: a first threshold for robot emergency stop control and a second threshold for welding wire feed control. This segmentation allows different response levels for different severity levels of external force, preventing false emergency stops while protecting against harmful continuous forces during welding initiation.
Solution Approach 2:
The patent applies different threshold values (first threshold and second threshold) for different control functions (robot stop control and wire feed control). This local quality approach allows the system to have high sensitivity for robot safety while being less sensitive for wire feed control during welding initiation, resolving the contradiction between safety reliability and preventing adverse effects.
2Ease of operation
If the external force detection threshold is set high to allow temporary external forces during welding start, then false emergency stops are prevented, but continuous external forces during welding start can adversely affect the robot and welding torch
Solution Approach 1:
The patent implements dynamic threshold selection based on the welding state. During welding initiation, the second threshold (for wire feed control) is applied, which is higher than the first threshold, allowing temporary external forces that occur during normal welding start. This dynamic adjustment ensures smooth welding initiation while maintaining protection against harmful continuous forces through the first threshold for robot safety.
Data Source
AI summary
A robot control device according to one embodiment of the present disclosure is capable of appropriately starting welding and controls a robot that performs welding of a welded object by using a welding torch that feeds a welding wire. The robot control device comprises: a welding command unit that commands the welding; an external force acquisition unit that acquires a value of external force acting on the robot; a robot stopping unit that stops operation of the robot if a value acquired by the external force acquisition unit is a first threshold value or greater; and a wire stopping unit that stops feeding of the welding wire if a value acquired by the external force acquisition unit is a second threshold value or greater at the beginning of the welding.