Multi-Axis Machine Tool Calibration Using Integrated Kinematic Error Modeling
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Solution Overview
Problem
Current calibration methods for multi-axis machine tools are limited in accuracy and convenience, as they typically focus on optimizing one rotation axis at a time, requiring extensive measurements and not accounting for the global behavior of the machine tool, making them less effective for compensating positioning errors across multiple axes.
Innovation Solution
A calibration method that measures a calibration ball's position at different rotating axes positions, using a kinematic model and optimization algorithm to combine positioning errors from multiple axes, generating a compensation model that accounts for the entire kinematic chain, allowing for accurate compensation of translational and rotational movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If calibration methods focus on optimizing one rotation axis at a time, then the calibration process becomes simpler and more manageable, but the calibration quality and positioning accuracy for multi-axis machine tools is limited
Solution Approach 1:
The patent combines the calibration of multiple rotation axes into a single integrated measurement process. Instead of calibrating each axis separately, the method simultaneously measures positioning errors across all rotation axes by moving a calibration object through multiple axes and capturing errors in a comprehensive measurement dataset, thereby achieving both operational simplicity and high calibration quality
Solution Approach 2:
The calibration method uses a universal measurement approach that works for all rotation axes simultaneously. The measurement system is designed to capture positioning errors for multiple axes in a single calibration run, making the calibration process multi-functional and applicable to the entire multi-axis system rather than requiring separate specialized procedures for each axis
2Device complexity
If kinematic errors are determined based on subsets of positioning errors from individual axes, then the measurement process becomes less complex, but the accuracy of error identification is reduced
Solution Approach 1:
The patent merges the measurement data from all rotation axes into a unified kinematic error identification process. By combining positioning errors from multiple axes measured simultaneously, the method achieves accurate identification of kinematic errors for the entire system while maintaining manageable process complexity through automated data processing
3Manufacturing precision
If extensive measurements are conducted to achieve accurate calibration across multiple axes, then calibration quality improves, but measurement time increases
Solution Approach 1:
The calibration method implements continuous measurement across all rotation axes simultaneously rather than performing sequential measurements. The measurement system continuously captures positioning errors as the calibration object moves through the multi-axis workspace, eliminating idle time between axis calibrations and achieving comprehensive calibration accuracy without excessive measurement time
Solution Approach 2:
The method performs preliminary setup by defining a calibration object with known geometric features that can be measured from multiple angles and positions. This preliminary preparation enables the subsequent simultaneous measurement of all rotation axes to proceed efficiently without requiring extensive sequential adjustments during the actual calibration process
Data Source
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AI summary
The present invention relates to a calibration method for numerical controlled machine tools (1), which uses a kinematic model to generate a compensation model for the positioning error occurring with the movement of the linear (X, Y, Z) and rotation axes (B, C, A) of a machine tool (1). The calibration method measures the positions of a calibration ball (6) with a measurement sequence which includes the combined movement of the calibration ball (6) around two rotation axes (C, B or C, A), wherein the measurements around a first rotation axis (C) include at least two rotational position movements around a second axis (B or A).