Holding Apparatus Positional Deviation Correction via Force Feedback
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Solution Overview
Problem
Industrial robots face challenges in accurately positioning and holding diverse shapes and sizes of workpieces due to finger warping, which causes positional deviations, especially when switching between position and force control modes.
Innovation Solution
A method for controlling a holding apparatus that calculates and corrects positional deviations of workpieces by using holding force information and correction factors, allowing the fingers to adjust their relative postures and positions to maintain precise placement across various workpiece shapes and sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position control is used to hold workpieces, then positioning precision is improved, but finger warping causes positional deviations that reduce accuracy
Solution Approach 1:
The control apparatus calculates the actual holding force applied by each finger and uses this feedback to compute correction amounts for positional deviations. The system continuously monitors holding force and adjusts finger positions accordingly to compensate for warping effects, maintaining positioning accuracy despite the mechanical deformation.
Solution Approach 2:
The system changes the control parameter from simple position control to a composite control that incorporates holding force information. By calculating correction amounts based on actual holding force values and predetermined correction factors, the system adapts the control parameters to compensate for finger warping and maintain positioning precision.
2Adaptability or versatility
If force control is used to hold workpieces, then adaptability to different workpiece shapes is improved, but positioning accuracy deteriorates due to finger warping
Solution Approach 1:
The control apparatus uses feedback from holding force sensors to calculate actual holding forces and determines correction amounts for positional deviations. This feedback mechanism allows the system to maintain positioning accuracy while adapting to different workpiece shapes through force control, as the correction amounts are dynamically adjusted based on actual holding conditions.
Solution Approach 2:
The system dynamically adjusts finger positions based on real-time holding force measurements. By calculating correction amounts that vary with the actual holding force and workpiece characteristics, the system enables adaptive positioning that maintains accuracy across different workpiece shapes and sizes while under force control.
3Manufacturing precision
If the robot hand structure is made rigid to prevent warping, then positioning accuracy is improved, but the ability to handle diverse workpiece shapes and sizes is reduced
Solution Approach 1:
Instead of making the hand structure rigid, the system uses feedback from holding force measurements to calculate and apply correction amounts for positional deviations. This allows the flexible hand structure to maintain positioning accuracy by dynamically compensating for warping effects through control calculations rather than mechanical rigidity.
Solution Approach 2:
The invention replaces mechanical rigidity with a computational control system. Rather than designing a rigid hand structure to prevent warping, the system substitutes mechanical stiffness with software-based correction that calculates positional deviations from holding force data and applies appropriate corrections, thereby maintaining both flexibility and positioning accuracy.
4Measurement precision
If correction factors are predetermined for different holding forces, then correction accuracy is improved, but device complexity increases
Solution Approach 1:
The system performs preliminary calibration to determine correction factors for different holding forces before actual operation. These predetermined correction factors are stored and retrieved during operation, allowing accurate correction without real-time complex calculations. The preliminary action of creating lookup tables simplifies the operational control while maintaining high correction accuracy.
Data Source
AI summary
A method of controlling a holding apparatus configured to hold plural kinds of target objects by plural fingers in plural relative postures includes calculating, on a basis of information about holding force of the fingers in a relative posture for a target object, an amount of positional deviation of the target object held by the fingers, and correcting, on a basis of the amount of positional deviation calculated in the calculating, a position of the target object held by the fingers.