Two-Arm Hand-Eye Calibration With a Moving Camera and Small Pattern
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Solution Overview
Problem
Conventional hand-eye calibration methods for two-armed robots are inefficient and difficult to diagnose when the robot base is fixed, especially during simple motion, as they require an optimized geometric relationship between the robot and a pattern, which is challenging to achieve with a camera mounted on both arms.
Innovation Solution
A hand-eye calibration system where a camera is mounted on one arm of a two-armed robot, and a small pattern is mounted on the other arm, allowing for the movement of both the camera and the robot to acquire posture information and images repeatedly, enabling effective hand-eye calibration by matching the coordinate information of the small pattern with the checkerboard coordinates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a camera is mounted on both arms of a two-armed robot to perform hand-eye calibration, then the geometric relationship between robot and pattern can be optimized, but the system complexity and difficulty of diagnosis increase
Solution Approach 1:
The patent extracts one camera from the dual-camera configuration and mounts it only on one arm of the two-armed robot. This simplifies the system by removing unnecessary complexity while maintaining calibration effectiveness. The single camera on one arm, combined with a pattern on the other arm, achieves the required geometric relationship without the complications of dual-camera synchronization and coordination.
2Stability of the object's composition
If the robot base is fixed during calibration, then stability is maintained, but the efficiency and diagnosability of calibration decrease
Solution Approach 1:
The patent introduces dynamic movement capabilities during calibration by allowing the robot arm with the camera to move to multiple predetermined positions. This dynamic approach replaces static fixed-base calibration with a mobile calibration method that maintains stability through controlled positioning while significantly improving efficiency and diagnosability through repeated measurements at different locations.
Solution Approach 2:
The calibration process employs periodic action by moving the camera-equipped robot arm to multiple predetermined positions in a systematic sequence. This periodic movement pattern allows for repeated measurements at different locations, improving both the efficiency and diagnosability of the calibration process while maintaining overall system stability through controlled, repetitive motion cycles.
3Measurement precision
If a large checkerboard pattern is used for calibration, then measurement accuracy is improved, but the space requirement and setup complexity increase
Solution Approach 1:
The patent uses a small pattern that can be mounted on the robot arm itself, effectively creating a movable copy of the calibration target. This small pattern, when combined with the camera's movement to multiple positions, achieves the same calibration accuracy as a large stationary checkerboard would provide, while requiring minimal space and reducing setup complexity.
Data Source
AI summary
A hand-eye calibration system and method are provided. The system includes a robot on which a small pattern is mounted, a camera configured to photograph the robot, a memory, and a processor configured to move the robot, acquire posture information of the moved robot, acquire an image from the camera, move the camera after performing the robot movement, the posture information acquisition, and the image acquisition a first predetermined number of times, and perform hand-eye calibration for the robot based on the posture information and the images, which are obtained by repeatedly performing of the robot movement, the posture information acquisition, the image acquisition, and the camera movement.