Robot Touch-Probe Calibration for Workpiece Frame Alignment
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Solution Overview
Problem
Existing robot calibration methods require high operator interaction, leading to time-consuming and inaccurate processes, especially when maintaining the positional relationship between a robot and a work object with relative movement.
Innovation Solution
A method involving a robot system with a touch probe that measures and stores coordinates from multiple locations on a work object's surfaces to calculate the orientation and origin of the work object frame of reference relative to the robot frame of reference, using a motion control module, calculation module, and memory module to determine the positional relationship efficiently and accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual movement method is used for robot calibration, then the robot can be calibrated to reach desired positions, but the process becomes extremely time consuming and inaccurate due to high operator interaction
Solution Approach 1:
The patent replaces manual mechanical positioning with an automated touch probe system. The touch probe automatically touches multiple predetermined locations on the work object to collect coordinate data, eliminating the need for manual operator interaction and mechanical positioning adjustments.
Solution Approach 2:
The system performs self-calibration by automatically collecting data from multiple touch locations and computing the transformation matrix between robot coordinates and work object coordinates without requiring external operator intervention at each measurement point.
2Measurement precision
If multiple touch locations are measured on work object surfaces, then the orientation and origin of work object frame can be calculated accurately, but the measurement and data collection process becomes more complex
Solution Approach 1:
The calibration process is segmented into three independent surface measurements (first surface, second surface, third surface), each contributing specific coordinate data. This segmentation allows the complex problem of determining 3D orientation and origin to be broken down into manageable surface-by-surface measurements.
Solution Approach 2:
The touch probe serves as an intermediary device that bridges the robot coordinate system and the work object coordinate system. By touching multiple predetermined locations, it collects intermediate coordinate data that is then processed to determine the transformation relationship between the two reference frames.
Data Source
AI summary
A method for calibration of work piece mounted in a predetermined manner to a work object and a robot system using the same. The work object has a first surface, a second surface and a third surface, and wherein the work object frame of reference is defined by a first coordinate line, a second coordinate line, and a third coordinate line at intersections of the first surface, the second surface and the third surface converging on a point. The method includes: touching a first number of locations on the first surface of the work object positioned by the robot touch probe to measure their actual locations on the first surface in the robot frame of reference, and storing the measured first coordinates for the measured locations; touching a second number of locations on the second surface of the work object positioned by the robot touch probe to measure their actual locations on the second surface in the robot frame of reference, and storing the measured second coordinates for the measured locations; touching a third number of locations on the third surface of the work object positioned by the robot touch probe to measure their actual locations on the third surface in the robot frame of reference, and storing the measured third coordinates for the measured locations; calculating orientation and origin of the work object frame of reference from the robot frame of reference based on the measured first, second and third coordinates for the measured locations, where the work object is positioned in the robot cell. The method provides all the necessary data to determine orientation and origin of the actual work object frame of reference relative to the robot frame of reference. The method also enables the robot to perform machine operations accurately at locations on a work object.