Stacked Unit Load Removal Using Identification Mark Positioning
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Solution Overview
Problem
Existing methods for removing a unit load from a stack in transfer stations face challenges such as difficulty in recognizing unit load edges using image recognition and inability to determine the absolute position of unit loads, leading to unreliable results, especially in poor lighting conditions.
Innovation Solution
A method involving a gripping unit of an automatic transfer device that uses identification marks on unit loads, captured by an image capturing device and evaluated to determine the absolute position relative to unit load edges, allowing precise alignment and removal of unit loads, even in poor lighting conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If image recognition is used to capture unit load edges, then the method can identify unit loads, but the recognition proves difficult and yields reliable results only under perfect conditions
Solution Approach 1:
The patent introduces identification marks as an intermediary element between the unit loads and the image recognition system. These marks serve as reliable mediators that can be consistently detected by the camera, regardless of lighting conditions or unit load appearance variations. The marks translate the complex task of edge detection into a simpler task of mark recognition, resolving the contradiction between measurement precision and reliability.
Solution Approach 2:
The identification marks are designed with specific visual characteristics (contrasting colors, distinct patterns) that make them easily distinguishable from the unit loads themselves. This visual differentiation ensures that the image recognition system can reliably detect the marks without being confused by variations in unit load appearance, lighting conditions, or background elements, thereby improving both accuracy and reliability.
2Loss of information
If barcodes are arranged on unit loads to store height information, then lifting height can be determined, but the absolute position of unit loads in the stack cannot be determined
Solution Approach 1:
The patent transitions from one-dimensional barcode information (storing only height data) to two-dimensional spatial information by placing identification marks at specific positions on unit load faces. The image recognition system captures the spatial coordinates of these marks, providing absolute position information in both horizontal and vertical dimensions. This dimensional expansion resolves the information loss while maintaining relatively simple system complexity.
3Measurement precision
If identification marks are arranged at defined positions on unit loads, then precise position determination is achieved, but the system must handle both identifiable and non-identifiable loads
Solution Approach 1:
The system implements a feedback mechanism where the image recognition unit continuously monitors unit load positions and identifies loads with or without marks. When non-identifiable loads are detected, the system can adjust its operation accordingly, such as using alternative detection methods or alerting operators. This feedback loop maintains high precision for identifiable loads while providing adaptability to handle mixed scenarios, resolving the contradiction between precision and versatility.
Data Source
AI summary
A method for removing a unit load from a stack by means of an automatic transfer device includes capturing an image of the stack by means of an image capturing unit, which image is evaluated by means of an evaluation unit in order to recognize an identification mark arranged on the unit load and identify the unit load. The unit load data assigned to the unit load are read out from a database, from which unit load data an edge position of the unit load can be computed. The transfer device can be controlled on the basis of the edge position in order to remove the unit load. The present disclosure further relates to a transfer station with a transfer device and a computer-implemented method for generating a movement specification for the automatic transfer device.