Three-Dimensional Sensor Calibration with Fixed-Camera Spatial Mapping
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Solution Overview
Problem
Conventional calibration techniques for three-dimensional distance sensors are processing-intensive, require mechanical accuracy, and struggle with focus shifts and optimal exposure conditions, necessitating multiple pattern changes and manual labor.
Innovation Solution
A method using an external camera with a fixed position to correlate image positions of a projection pattern with spatial positions, eliminating the need for calibration patterns and relying on machine accuracy for calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration techniques are used, then calibration can be performed, but processing complexity and time increase significantly
Solution Approach 1:
The patent extracts the calibration pattern recognition step from the calibration process. By using an external camera to directly capture the projection pattern and calculate spatial positions without requiring pattern identification, the method eliminates processing-intensive pattern matching while maintaining calibration accuracy.
Solution Approach 2:
The patent replaces mechanical calibration procedures (physical pattern placement, manual alignment) with a computational approach using an external camera to directly measure spatial positions. This substitution of mechanical operations with optical-mechanical measurement reduces both time and processing complexity.
2Measurement precision
If multiple calibration patterns are used, then calibration accuracy can be improved, but device complexity and manual labor increase
Solution Approach 1:
The patent makes the external camera perform multiple functions: it captures the projection pattern, determines spatial positions of light points, and provides reference data for calibration. This single device replaces what would otherwise require multiple specialized calibration artifacts and procedures.
Solution Approach 2:
The external camera system performs self-calibration by autonomously capturing images and calculating spatial positions without requiring manual intervention for pattern placement or alignment. The system serves itself by using the projection pattern as both the calibration target and the measurement reference.
3Measurement precision
If mechanical accuracy is required for calibration, then measurement precision can be maintained, but ease of operation decreases
Solution Approach 1:
The patent replaces mechanical alignment and positioning requirements with an optical measurement system. The external camera captures spatial positions directly through imaging, eliminating the need for precise mechanical placement of calibration patterns and reducing operational complexity.
Data Source
AI summary
An example method includes controlling a projecting subsystem of a distance sensor to project a projection pattern onto a target object, wherein the projection pattern comprises a plurality of points of light, 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, 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.