Robot Calibration System Using Segmented Laser Reflectors
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Solution Overview
Problem
Off-line teaching of robots often results in position calibration errors due to assembly errors and gravitational influences, leading to operational failures, as the actual position of the robot's distal end differs from the simulated position.
Innovation Solution
A measurement system with reflectors mounted on the robot's distal end, a laser head, and a head driving device, controlled by a robot control apparatus that uses calibration operation programs to accurately position the robot at multiple measurement points, ensuring precise calibration by preventing overlap of incident ranges and adjusting for gravitational deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple reflectors are mounted at the distal end portion of the robot to enable position measurement, then measurement capability is improved, but the risk of measuring unintended reflectors increases
Solution Approach 1:
The incident ranges of multiple reflectors are arranged in different directions so that each reflector's measurement zone is segmented and separated from others. This prevents the laser beam from accidentally hitting unintended reflectors while maintaining the ability to measure positions accurately at multiple orientations.
Solution Approach 2:
Each reflector is given a specific directional incident range tailored to its intended measurement purpose. The incident ranges are locally optimized for different spatial directions, ensuring that each reflector responds only to laser beams from its designated direction, thus preventing cross-measurement errors.
2Adaptability or versatility
If the laser head orientation is changed dynamically during measurement, then measurement flexibility is improved, but the time required for calibration increases
Solution Approach 1:
The incident ranges of all reflectors are pre-configured in different directions during system setup. This preliminary arrangement allows the measurement system to directly select and measure from the appropriate reflector based on the current robot orientation, eliminating the need for dynamic laser head reorientation and reducing calibration time.
Solution Approach 2:
The system dynamically selects which reflector to measure based on the current robot position and orientation, rather than physically reorienting the laser head. This dynamic selection approach maintains measurement flexibility while significantly reducing the time required for calibration.
3Measurement precision
If the robot is controlled to move gradually to compensate for gravitational deflection, then measurement accuracy is improved, but the complexity of control increases
Solution Approach 1:
The system uses feedback from the measured positions to calculate and compensate for gravitational deflection effects. By continuously monitoring position deviations and applying corrections based on pre-characterized gravitational influence data, the system achieves high measurement accuracy without requiring complex real-time control mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This system enables accurate calibration of the robot's position, reducing errors to less than 1 mm, improving operational reliability and efficiency by minimizing the time required for calibration and preventing unintended reflector measurement.
Implementation Method 1
a laser head which emits a laser beam toward the reflectors and receives a reflected light from the reflectors
Data Source
AI summary
A measurement system includes a plurality of reflectors of a robot, a measurement apparatus having a laser head which emits a laser beam toward the reflectors and which receives a reflected light from the reflectors, a head driving device which changes orientation of the laser head, and a robot control apparatus which controls the robot based on the calibration operation program and which sequentially places the distal end portion of the robot at a plurality of measurement positions for conducting calibration. The robot control apparatus conducts a head drive control process of receiving controller coordinate data of any one of the plurality of reflectors, which is used at the time of sequentially placing the distal end portion of the robot at plurality of measurement positions, and sending a control signal for changing the orientation of the laser head to the head driving device by using the received controller coordinate data.