Robot-Vision Calibration With Iterative Error Map Compensation
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Solution Overview
Problem
Robotic manipulators in industrial setups experience accuracy degradation over time, leading to potential failures in high-precision operations, especially in vision-guided setups, due to the lack of regular and expensive calibration procedures.
Innovation Solution
An iterative calibration system that uses low-cost in-process 2D sensing devices to iteratively adjust robot kinematic parameters and correct hand-eye transformations, utilizing existing sensors within the robotic cell to improve accuracy without requiring additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If regular calibration procedures are performed to maintain robotic accuracy, then positioning precision is improved, but operational time and cost increase
Solution Approach 1:
The system performs self-calibration using its own vision system and existing sensors to detect and correct positioning errors autonomously during operational periods, eliminating the need for external calibration specialists and reducing calibration time while maintaining precision
Solution Approach 2:
The vision system continuously monitors robot positioning and provides real-time feedback on deviations from expected positions, enabling dynamic correction of kinematic parameters without stopping operations, thus maintaining precision without sacrificing operational time
2Measurement precision
If expensive specialized calibration equipment is used to maintain accuracy, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The system uses the robot's existing vision system and sensors for multiple purposes: normal operation guidance, positioning error detection, and calibration measurements, eliminating the need for specialized calibration equipment and reducing overall system complexity while maintaining calibration precision
Solution Approach 2:
The robot calibrates itself using its own built-in vision system and sensors rather than requiring external specialized equipment, reducing device complexity and cost while achieving the necessary calibration precision through self-diagnosis and self-correction
3Productivity
If high-precision robotic operations are performed without frequent calibration, then productivity is improved, but positioning accuracy deteriorates
Solution Approach 1:
The vision-based error detection and correction operates continuously during robot operation without interrupting productive tasks, allowing the system to maintain positioning accuracy throughout extended operational periods without frequent calibration stops
Solution Approach 2:
Real-time vision monitoring provides continuous feedback on positioning errors during operations, enabling dynamic adjustment of kinematic parameters to maintain accuracy while keeping the robot productive, thus resolving the trade-off between throughput and precision
Data Source
AI summary
A method of calibrating a robotic arm which includes perform iterative eye-in-hand and robot calibration, using a calibrated end of arm camera with known intrinsic parameters and a static target, to obtain eye-in-hand transformations and robotic parameters. The method further uses robotic parameters to estimate pose of end of arm, for eye-to-hand calibration, to obtain eye-to-hand transformations and calculates final error compensation based on the robotic parameters, eye-to-hand transformations, and eye-in-hand transformations. In one embodiment, the method calculates a robot positioning error map function, the robot positioning error map function used to adjust movement parameters for the robotic arm.