Automatic Needle Position Calibration via Optical Deviation Detection
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Solution Overview
Problem
Manual calibration of needle position in automatic sewing machines is labor-intensive and limited by human judgment, leading to inaccuracies and the need for repeated calibration for different sewing programs and pallets.
Innovation Solution
An automatic calibration method using an image capturing device and a controller to determine the deviation of the needle position relative to the coordinate system by analyzing images of a pallet with a reference mark and a test hole, allowing for precise adjustment of the needle position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual calibration is performed by operator adjustment, then the calibration process can be completed, but the accuracy is limited to about +/-0.2 mm and requires repeated adjustments for different pallets
Solution Approach 1:
The patent replaces the manual mechanical adjustment system with an automated optical measurement system. An image capturing device takes photographs of the pallet and needle position, and a controller automatically processes these images to calculate and adjust the needle position coordinates, eliminating the need for manual visual inspection and adjustment by the operator.
Solution Approach 2:
The patent creates a visual copy (photograph) of the actual needle and pallet position. The image capturing device produces a photograph that is processed by the controller to determine the needle position relative to the pallet, replacing direct visual inspection with image-based measurement and analysis.
2Adaptability or versatility
If manual calibration is performed for each pallet, then the calibration can be adapted to specific pallets, but the process becomes labor intensive and time consuming
Solution Approach 1:
The system performs self-calibration by automatically capturing images of the pallet and needle, processing these images through the controller, and calculating the corrected needle position coordinates without requiring operator intervention. The system serves itself by completing the entire calibration process autonomously for each different pallet.
Solution Approach 2:
The patent changes the calibration parameters automatically by calculating corrected X and Y coordinates of the needle based on image analysis. The controller processes the photograph to determine the actual needle position and generates updated coordinate parameters that adapt to each specific pallet configuration.
3Reliability
If the needle position is not accurately calibrated, then the sewing machine can operate, but the workpiece may be sewed inappropriately even if the X-Y table is controlled according to the sewing program
Solution Approach 1:
The patent introduces an intermediary calibration system consisting of the image capturing device and controller that mediates between the needle position and the coordinate system. This intermediary automatically measures and corrects the needle position, ensuring accurate correspondence between the programmed coordinates and actual needle location without requiring complex manual adjustment mechanisms.
Data Source
AI summary
A method for automatic calibration of a needle position relative to a coordinate system of a sewing machine includes: controlling a X-Y table to move a pallet to bring a sheet under a needle, lowering the needle to penetrate the sheet to form a needle hole and raising the needle, controlling the X-Y table to move the pallet to bring a reference mark and the test hole into an FOV of an image capturing device, obtaining an image of the pallet which contains the reference mark and the needle hole, determining an amount of separation of the needle hole from the reference mark in the image, and calibrating the needle position relative to the coordination system based on the amount of separation thus determined and a reference distance.