Triangulation Sensor Array for Shiny Part Inspection
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Solution Overview
Problem
Current automatic inspection methods for manufactured parts, particularly ammunition cases and threaded fasteners, face challenges such as the obscuration of laser lines due to inter-reflection, difficulty in measuring shiny surfaces with complex geometry, and the need for part rotation, which increases inspection time and complexity.
Innovation Solution
A high-speed, triangulation-based 3-D method and system that uses angularly-spaced sensor heads to generate focused lines of radiation, sense reflected lines, and process 2-D profile signals to obtain a 360° panoramic composite 3-D view of parts without requiring part rotation, identifying defects like cracks, splits, and thread profile parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional laser triangulation is used to inspect shiny surfaces, then measurement is possible, but inter-reflection obscures the laser lines making measurement difficult
Solution Approach 1:
The patent employs asymmetric illumination angles where the laser beam is projected at a specific angle (e.g., 45 degrees) relative to the surface normal, rather than perpendicular incidence. This asymmetric arrangement ensures that specular reflections are directed away from the detector, preventing inter-reflection obscuration while maintaining measurement capability on shiny surfaces
Solution Approach 2:
The patent introduces an intermediary optical element (such as a beam splitter or dichroic mirror) that separates the illumination path from the detection path. This intermediary component allows the laser beam to illuminate the surface while directing only the diffusely reflected light to the detector, blocking the direct specular reflection path and eliminating inter-reflection interference
2Measurement precision
If parts are rotated during inspection to view all surfaces, then complete inspection is achieved, but inspection time increases
Solution Approach 1:
The patent transitions from a single-point or single-line measurement approach to a two-dimensional array of sensors that capture the entire surface simultaneously. This dimensional expansion allows complete 360-degree surface inspection without mechanical rotation, as all sensor elements detect different angular positions at the same time
Solution Approach 2:
The patent creates multiple optical copies of the measurement function through an array of sensors, each capturing a different angular view of the part. This parallel copying approach eliminates the need for sequential rotation and measurement, as all angular information is acquired simultaneously through the sensor array
3Measurement precision
If multiple sensor heads are used to inspect complex surfaces, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent divides the measurement task into multiple segments by using an array of sensors, each responsible for detecting light from a specific angular direction. This segmentation allows comprehensive surface coverage while maintaining manageable complexity, as each sensor element is a simple, identical component rather than a complex single sensor
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
Enables efficient, high-speed inspection and sorting of parts with improved accuracy and reduced inspection time by overcoming inter-reflection challenges and eliminating the need for part rotation, effectively identifying defects and thread parameters on complex surfaces.
Implementation Method 1
delivering the focused lines onto a plurality of exterior side surfaces of the part during motion of the part relative to the focused lines to obtain corresponding arrays of reflected lines of radiation
Implementation Method 2
Each of the sensor heads is configured to generate focused lines of radiation and to sense corresponding reflected lines of radiation
Data Source
AI summary
High-speed, triangulation-based, 3-D method and system for inspecting manufactured parts and sorting the inspection parts are provided. A plurality of angularly-spaced, triangulation-based, sensor heads are located at an imaging station to simultaneously deliver focused lines of radiation onto a plurality of exterior side surfaces of the part during motion of the part relative to the focused lines to obtain corresponding arrays of reflected lines of radiation. The sensor heads simultaneously sense their corresponding arrays of reflected lines to obtain corresponding sets of 2-D profile signals. Each set of profile signals represent a 3-D view of one of the exterior side surfaces and the sets of 2-D profile signals represent a 360° panoramic composite 3-D view of the outer peripheral surface of the part.