Robot Camera Calibration Using a Shared Pattern Reference
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Solution Overview
Problem
Existing robot systems face challenges in calibrating external cameras installed separately from the robot arm, as they require the hand-end camera to be positioned at multiple locations, necessitating extensive robot arm movement and time-consuming operations, limiting their applicability when the camera is not at the robot arm's tip end.
Innovation Solution
A robot system with a first camera installed on the robot arm or its base and a second camera positioned separately, where the control device uses the first camera to image a calibration pattern and acquire data, allowing for efficient calibration of the second camera by capturing images from outside its field of view, enabling quick and accurate calibration before starting work.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hand-end camera is installed at the tip end of the robot arm and the robot arm is moved to multiple positions for calibration, then the external camera can be calibrated, but the calibration process takes considerable time and the method cannot be applied when the camera is installed at a place other than the tip end
Solution Approach 1:
The calibration pattern is positioned at a calibration position that can be imaged by both the first camera (on the robot) and the second camera (external) before the robot arm moves to perform work. This preliminary positioning eliminates the need for moving the robot arm to multiple calibration positions, significantly reducing calibration time while maintaining accuracy
Solution Approach 2:
A calibration pattern serves as an intermediary object that enables calibration of the external camera. The pattern is imaged by both the first camera (with known calibration data) and the second camera, allowing the processor to calculate the external camera's calibration data by comparing the images and using the known first camera calibration data as a reference
2Measurement precision
If the robot arm is moved to a plurality of positions and orientations to calibrate the external camera, then calibration data can be obtained, but the operation of the robot arm is indispensable and calibration takes considerable time
Solution Approach 1:
The system performs calibration imaging at a single predetermined calibration position before work begins, rather than requiring the robot arm to move to multiple positions during work. This preliminary action at a fixed position dramatically improves calibration efficiency while maintaining the ability to obtain accurate calibration data through dual-camera imaging
Solution Approach 2:
The first camera mounted on the robot serves dual functions: it images the work area during normal operation and images the calibration pattern during calibration. This multi-functionality eliminates the need for separate calibration equipment and robot movements, improving both efficiency and productivity
Data Source
AI summary
A robot system includes a robot including a robot arm and a first camera, a second camera installed separately from the robot, and a control device which controls the robot and the second camera. The first camera has already been calibrated in advance, and a first calibration data which is the calibration data between the coordinate system of the robot and the coordinate system of the first camera is known. The control device (i) images a calibration pattern with the first camera to acquire a first pattern image and images a calibration pattern with the second camera to acquire a second pattern image, and (ii) executes calibration process for obtaining a second calibration data which is the calibration data between the coordinate system of the robot and the coordinate system of the second camera using the first pattern image, the second pattern image, and the first calibration data.