Active Ranging Scanner Assembly Inspection
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Solution Overview
Problem
Existing methods for assembly completeness inspection of large structures like car bodies of railway vehicles are time-consuming and inefficient, particularly when dealing with steel structures, as they require extensive photography and struggle with accurately reflecting strip patterns, and fail to account for assembly tolerances.
Innovation Solution
The use of an active ranging scanner, such as a LIDAR scanner, to create a 3D model of the assembled structure, which is then compared to a CAD-generated 3D model, allowing for quick and accurate inspection by subdividing the models to account for tolerances and identifying missing parts through a best fit algorithm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a digital camera is moved around the structure to take numerous pictures of small sections, then assembly completeness can be inspected, but the inspection process becomes very time consuming
Solution Approach 1:
The patent divides the large assembled structure into multiple smaller sections or regions of interest. Instead of capturing the entire structure in one go or moving a camera around, the inspection system focuses on segmented areas independently, allowing parallel processing and faster inspection while maintaining completeness.
Solution Approach 2:
The patent transitions from 2D camera imaging to 3D active ranging scanning. By using depth information and spatial coordinates from multiple scanning positions, the system creates a comprehensive 3D representation of the assembled structure, enabling complete inspection without physically moving a camera around the object.
2Measurement precision
If a strip pattern is projected onto the structure sections for picture capture, then high quality pictures can be obtained, but the method is not well adapted to steel structures because strip patterns are not well reflected by steel
Solution Approach 1:
The patent replaces the optical projection and reflection-based strip pattern method with active ranging technology using laser scanners. Instead of relying on visual reflection of projected patterns, the system uses time-of-flight or phase-shift laser ranging to directly measure distance and create 3D point clouds, which works effectively on all surfaces including non-reflective steel surfaces.
3Reliability
If the entire structure is scanned to ensure complete inspection, then all mounting parts can be detected, but the complexity of processing and comparing large quantities of data increases
Solution Approach 1:
The patent segments both the physical structure into measurable sections and the resulting point cloud data into corresponding spatial regions. This segmentation allows the system to process and compare data region-by-region rather than handling the entire structure's data as one massive dataset, reducing computational complexity while maintaining complete coverage.
Solution Approach 2:
The patent applies different processing strategies to different regions based on their specific characteristics. High-priority areas with critical mounting parts receive more detailed processing and comparison, while less critical areas use streamlined processing. This localized approach optimizes the balance between detection reliability and processing complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables fast, automated, and reliable completeness inspection of large assembled structures, including steel surfaces, by eliminating the need for extensive photography and effectively handling assembly tolerances, thereby improving inspection efficiency and accuracy.
Implementation Method 1
an active ranging scanner such as a LIDAR scanner can scan the whole structure with a laser beam
Implementation Method 2
an active ranging scanner such as a LIDAR scanner can scan the whole structure with a laser beam from a few different positions
Data Source
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AI summary
A method for completeness inspection of an assembled structure to check whether said structure has all the mounted parts comprising: a) Scanning the whole assembled structure with an active ranging scanner, thus obtaining a 3D picture (100); b) Obtaining a 3D model (200) of the whole structure based on CAD data; c) Subdividing said 3D picture into a number of smaller picture comparison areas (104) and said 3D model into a number of smaller corresponding model comparison areas (204) using a best fit algorithm, thus obtaining a set of final picture comparison areas and corresponding final model comparison areas; d) For each final model comparison area, identifying desired mounting parts located therein and searching for mounted parts in the corresponding final picture comparison area that match said desired mounting parts; and e) Identifying the desired mounting parts, which have no matching mounted part in the final picture comparison areas, as missing from the assembled structure.