Dual-Pattern Optical 3D Dimensioning Thermal Stability
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Solution Overview
Problem
Optical 3D dimensioning systems face accuracy losses due to variations in projector-camera pair positions and orientations caused by thermal changes, structural deformations, and material thermal expansion differences, which are difficult to control or correct with calibration.
Innovation Solution
A dual-pattern optical dimensioning system using a single piece optical component with a light collimator, splitter, and pattern generators producing interlaced or complementary patterns, along with a processing system to detect and analyze these patterns, minimizing the impact of thermal expansions and orientation variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is used to correct position and orientation variations, then measurement precision is improved, but reliability deteriorates due to non-calibratable variations from shock, vibration, and thermal changes
Solution Approach 1:
The patent changes the geometric parameters of the triangular system by introducing adjustable spacers between the camera module and projector, allowing the baseline distance to be modified. This enables the system to adapt to thermal expansions and mechanical deformations by recalibrating the physical dimensions of the rig rather than relying solely on software correction, thereby maintaining measurement precision under varying environmental conditions
Solution Approach 2:
The patent performs preliminary calibration by measuring the actual baseline distance with a laser distance meter and adjusting the spacers before operation. This pre-adjustment compensates for expected thermal expansions and mechanical variations, ensuring the system maintains reliability and accuracy without requiring continuous correction during operation
2Ease of manufacture
If multiple materials with different thermal expansion coefficients are used in camera module construction, then ease of manufacture is improved, but measurement precision deteriorates due to differential thermal expansion causing pattern image position changes
Solution Approach 1:
The patent applies local quality by using different spacer materials with appropriate thermal expansion coefficients for specific locations in the rig. The spacers are strategically positioned at critical joints where differential expansion occurs, and their material composition is selected to compensate for the thermal expansion differences between the camera module's silicon sensor, glass lens, and plastic parts, thereby maintaining pattern image position accuracy while allowing the use of multiple materials for ease of manufacture
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
The system achieves improved accuracy and robustness in 3D dimensioning by using interlaced or complementary patterns that are less affected by thermal changes and material expansions, maintaining precision despite camera focusing and distortion variations.
Implementation Method 1
a light collimator component orientated to receive light from the light emitting assembly and output collimated light
Implementation Method 2
a light splitter component orientated to receive the collimated light and split the collimated light into a first light beam and a second light beam
Implementation Method 3
a first pattern generator component orientated to produce a first pattern using the first light beam. The single piece optical component further comprises a second pattern generator component orientated to produce a second pattern using the second light beam
Data Source
AI summary
An optical dimensioning system includes one or more light emitting assemblies configured to project one or more predetermined patterns on an object; an imaging assembly configured to sense light scattered and/or reflected off the object, and to capture an image of the object while the patterns are projected; and a processing assembly configured to analyze the image of the object to determine one or more dimension parameters of the object. The light emitting assembly may include a single piece optical component configured for producing a first pattern and second pattern. The patterns may be distinguishable based on directional filtering, feature detection, feature shift detection, or the like. A method for optical dimensioning includes illuminating an object with at least two detectable patterns; and calculating dimensions of the object by analyzing pattern separate of the elements comprising the projected patterns. One or more pattern generators may produce the patterns.