3D Sensor Calibration with Detection Windows and External Camera
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Solution Overview
Problem
Conventional calibration methods for three-dimensional distance sensors are processing-intensive, require manual labor, and struggle with accurate detection of calibration targets and projection patterns due to focus shifts and differing exposure conditions, limiting measurement accuracy.
Innovation Solution
A method using detection windows established through image processing techniques, combined with an external camera, to correlate image and spatial positions of projection pattern points, reducing the need for mechanical accuracy and optimizing post-calibration distance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration methods are used to ensure accurate detection of calibration targets and projection patterns, then measurement accuracy is improved, but processing intensity and manual labor requirements increase significantly
Solution Approach 1:
The patent establishes detection windows for each point in the projection pattern before actual distance measurement begins. These windows are pre-calculated based on the geometric relationship between the projecting subsystem and imaging subsystem, allowing the system to quickly locate points within predefined regions during calibration and operation, thereby reducing processing intensity while maintaining detection accuracy
Solution Approach 2:
The patent divides the image space into multiple detection windows, each corresponding to a specific point in the projection pattern. This segmentation allows the system to process each point independently within its designated window rather than analyzing the entire image, significantly reducing computational complexity and manual intervention requirements while preserving measurement precision
2Measurement precision
If conventional calibration methods are used to account for focus shifts and exposure conditions, then measurement accuracy is improved, but device complexity and processing requirements increase
Solution Approach 1:
The patent changes the approach from adjusting focus and exposure parameters during calibration to establishing detection windows based on geometric parameters. The detection windows are calculated using the known positions of the projecting subsystem and imaging subsystem, transforming the calibration problem from one requiring complex parameter adjustments to one solved through geometric computation, thereby reducing device complexity while maintaining measurement accuracy
3Measurement precision
If manual calibration procedures are used to ensure accurate point detection, then measurement precision is improved, but time consumption and productivity decrease
Solution Approach 1:
The patent enables the system to automatically establish detection windows and locate projection pattern points without manual intervention. The processing system automatically calculates window positions based on the geometric relationship between subsystems and autonomously performs point detection within these windows during calibration and operation, eliminating time-consuming manual procedures while maintaining detection accuracy
Data Source
AI summary
An example method includes controlling the projecting subsystem of a distance sensor to project a projection pattern onto a target object, controlling an imaging subsystem of the distance sensor to capture a first image of the projection pattern on the target object and an external camera having a fixed position to capture a second image of the projection pattern on the target object, calculating an image position of a first point of the plurality of points on an image sensor of the imaging subsystem, using a previously established detection window to locate the first point in the first image, calculating a spatial position of the first point on the target object, based on the second image, and storing the image position and the spatial position together as calibration data for the distance sensor.