Battery Pack Weld Location Detection Using Frame Reference Features
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Solution Overview
Problem
Conventional vision systems used in laser welding struggle to locate weld points on cylindrical battery cells, particularly when these points are obscured by components like busbars, foils, or current collectors, as they rely on visible features which are not always accessible.
Innovation Solution
A frame with visual and positional reference features, such as stubs or arcs, is used to guide the vision system in determining weld points, allowing it to interpolate lines and arcs to accurately position welds on obscured regions of the battery cells, while the processing circuitry generates welding control signals for precise welding operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional vision system is used to locate weld points on battery cells, then the system can detect visible features, but it cannot locate weld points that are obscured by busbars, foils, or current collectors
Solution Approach 1:
The patent introduces a frame with visual reference features (stubs, arcs, or other detectable markers) as an intermediary element. These reference features are positioned in known geometric relationships to the obscured weld points, allowing the vision system to detect the frame features and calculate the hidden weld point locations through geometric interpolation rather than directly viewing the weld targets themselves.
Solution Approach 2:
The frame creates a visible copy or representation of the spatial relationships that exist between visible and obscured features. By detecting the reference features in the frame and using known geometric transformations, the system reconstructs the positions of obscured weld points without directly observing them, effectively copying the spatial information from visible to hidden domains.
2Measurement precision
If multiple cameras and assembly stages are used to achieve accurate weld point positioning, then measurement precision improves, but device complexity and cycle time increase
Solution Approach 1:
The patent combines multiple measurement functions into a single frame structure. Instead of using separate cameras and assembly stages to achieve positioning, the frame integrates visual reference features that encode multiple geometric relationships in one structure, allowing a single vision system to determine positions of multiple weld points simultaneously through geometric calculations.
Solution Approach 2:
The frame with its reference features is prepared in advance with known geometric relationships to the weld points. This preliminary setup eliminates the need for complex real-time measurement systems, as the geometric information is pre-encoded in the frame structure itself, allowing the vision system to directly calculate weld point positions from detected frame features.
3Measurement precision
If multiple cameras and assembly stages are used to achieve accurate weld point positioning, then measurement precision improves, but cycle time increases
Solution Approach 1:
The frame allows the vision system to continuously determine weld point positions in a single operational sequence. By encoding all necessary geometric information in the frame structure, the system eliminates the need for multiple sequential measurement stages, maintaining continuous productive action throughout the positioning process.
Data Source
AI summary
A frame is described for positioning a battery using a vision system to determine at least one weld point on the battery. The frame includes at least one visual reference feature detectable by the vision system. The reference feature is used by the vision system to determine the weld point(s). For example, the at least one visual reference feature includes a pair of stubs that define a line, and the at least one weld point is determined based on the line. In a further example, the pair of stubs correspond to respective batteries, which are arranged adjacent to one another within the frame. In a further example, respective centers of the stubs are lined up along a center line extending from respective centers of respective end faces of the respective batteries. The vision system includes vision circuitry, processing circuitry coupled to the vision circuitry, and a weld system.