Machine Tool Geometric Error Calibration Using Photogrammetry
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current machine tool calibration methods are time-consuming due to the need for manual operator intervention to locate the calibration tool within the work volume, which limits industrial interest despite improving precision.
Innovation Solution
The method employs photogrammetric techniques to automatically determine the spatial position of the calibration tool using vision means, allowing the head with a gauge to move autonomously to the reference patterns, reducing calibration time by capturing multiple images from different orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual control is used to bring the head closer to the calibration tool, then the position gauge can precisely measure the reference patterns, but the calibration process becomes slow and time-consuming
Solution Approach 1:
The vision means captures images and determines the approximate spatial position of the calibration tool before the head moves to it. This preliminary positioning action eliminates the need for slow manual movement and searching, allowing the head to directly move to the correct location for precise measurement.
Solution Approach 2:
The patent replaces the manual mechanical control system with an automated vision-based system. The vision means uses optical fields to detect and determine the position of reference markers, substituting the manual mechanical positioning process with an automated optical-mechanical system that is both faster and more precise.
2Productivity
If photogrammetric techniques are used to automatically determine the spatial position of the calibration tool, then the calibration time is reduced, but the system complexity increases due to the addition of vision means
Solution Approach 1:
The vision means serves multiple functions: it captures images of the work volume, identifies reference markers, determines their spatial positions, and provides this information to the control unit. By making the vision system multi-functional, the patent reduces the need for separate dedicated components for each function, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The vision means automatically captures images and processes the spatial position information without requiring external manual intervention. The system serves itself by using the captured images to directly determine marker positions and guide the head movement, eliminating the need for additional control systems or manual operations.
3Measurement precision
If multiple images are captured from different orientations, then the precision in determining the spatial position of reference markers is improved, but the calibration time increases
Solution Approach 1:
The vision means captures multiple images from different orientations in a periodic sequence rather than continuously. This periodic capture approach allows the system to collect sufficient data for precise 3D position determination while minimizing the total time spent on image capture and processing.
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 approach significantly reduces the total calibration time while maintaining precision in geometric error correction, enabling the improved positioning to compensate for the time spent on calibration.
Implementation Method 1
The invention proposes the use of photogrammetric techniques to determine the approximate spatial position of the calibration tool within the work volume of the machine
Data Source
Figure 1
AI summary
The present invention relates to a method for calibrating the geometric errors of a machine tool with a head (5) which uses a position gauge (6) and a calibration tool (7) with reference patterns (8), the method comprising the steps of: arranging reference markers (9,10) in the tool (7) and in the head (5); using vision means (11) to capture at least one image of the work volume of the machine, the markers (9,10) being observable in said work volume; determining a spatial position for each one of the markers (9,10) using the image; determining the approximate spatial positions of the patterns (8) according to the spatial position of each one of the markers (9,10); moving the head (5) to the tool (7); determining the actual spatial positions of the patterns (8) by means of the position gauge (6); and correcting the geometric errors by processing the information of the approximate and actual spatial positions of the patterns (8).