Robot Force Control for Foreign Matter Detection in Workpiece Fixing
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Solution Overview
Problem
Foreign matter adhering to or caught between a workpiece and a fixing mechanism in a robot system can lead to reduced machining accuracy of the workpiece.
Innovation Solution
A robot controller equipped with a force detection unit that corrects the workpiece's position and posture relative to a fixing mechanism, using force and moment thresholds to detect and remove foreign matter, ensuring accurate machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a robot supplies a workpiece to a fixing mechanism without foreign matter detection, then the supply process is simple and fast, but machining accuracy deteriorates due to foreign matter caught between the workpiece and fixing mechanism
Solution Approach 1:
The patent implements feedback control by using a force detection unit to monitor forces during workpiece supply, comparing detected forces against threshold values to detect foreign matter presence, and automatically controlling the robot to remove foreign matter or adjust positioning, thereby maintaining machining accuracy through closed-loop feedback
Solution Approach 2:
The patent replaces complex mechanical inspection systems with a force detection unit that uses force sensing to indirectly detect foreign matter. Instead of mechanical probes or visual inspection systems, the invention uses force thresholds to infer the presence of foreign objects, simplifying the detection mechanism while maintaining high precision
2Measurement precision
If force control is used to correct workpiece position and posture, then positioning accuracy is improved, but the risk of foreign matter causing abnormal forces increases
Solution Approach 1:
The patent applies preliminary anti-action by establishing force threshold values before the workpiece supply process begins. These thresholds represent the maximum acceptable forces during normal operation, and when exceeded, trigger automatic corrective actions to prevent foreign matter from compromising positioning accuracy
Solution Approach 2:
The force detection unit continuously monitors forces during position and posture correction, providing real-time feedback to the control system. When abnormal forces indicating foreign matter are detected, the system automatically adjusts the correction process or halts operation to prevent compromised positioning
Data Source
AI summary
A control device and method for preventing machining precision from deteriorating due to foreign matter sandwiched between a workpiece and a fixing mechanism. The control device controls a robot configured to provide the workpiece to the fixing mechanism and that has a force detection unit for detecting force and moment applied to the workpiece. The control device includes a function for performing a force control to correct the position of the workpiece relative to the fixing mechanism while the robot supplies the workpiece to the fixing mechanism, and then correct the orientation of the workpiece relative to the fixing mechanism; and a function for determining that foreign matter is wedged between the workpiece and the fixing mechanism if, during correction of the position of the workpiece, the force detection unit detects that the moment acting in the direction that the orientation of the workpiece is corrected exceeds a threshold value.