Monocular Vision Measurement of CNC Contouring Error at High Traverse Speed
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Solution Overview
Problem
Existing methods for measuring high-dynamic large-range arbitrary contouring errors in CNC machine tools are limited, as they often rely on single-dimensional measurements, have restricted measurement ranges, and struggle with high-traverse speed conditions, leading to reduced accuracy and inability to assess dynamic performance effectively.
Innovation Solution
A monocular vision six-dimensional measurement method is developed, utilizing a measurement fixture and system with a small field of view and priori knowledge to enhance measurement accuracy, representing machine tool motion contours with reference primitives and computing six-dimensional errors through datum transformation, allowing for precise interpolation contour analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an R-test measurement method is used, then the measurement accuracy is high, but the measurement range is small with unidirectional ranges less than 12 mm
Solution Approach 1:
The patent extends measurement from limited linear ranges to large 3D spatial volumes by using multiple cameras to capture coordinates of multiple points distributed in space, achieving both high accuracy and large measurement range simultaneously
2Device complexity
If a monocular vision method with limited camera bandwidth is used, then the measurement system is simple, but the shooting frame frequency cannot be improved resulting in blurring effect at high traverse speed
Solution Approach 1:
The patent uses stroboscopic illumination that flashes at specific intervals synchronized with the camera exposure, creating periodic lighting that freezes motion at high speeds without requiring high frame frequency from the camera
Solution Approach 2:
The patent introduces stroboscopic light as an intermediary between the moving object and camera, using the light's temporal characteristics to capture sharp images of high-speed motion without increasing camera frame frequency
3Ease of manufacture
If a two-dimensional measurement method is used, then the measurement cost is reduced, but three-dimensional computation of contouring error cannot be realized
Solution Approach 1:
The patent combines multiple 2D camera views to reconstruct 3D spatial coordinates of measurement points, achieving three-dimensional measurement capability while using simple monocular cameras that keep costs low
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 method enhances measurement accuracy and range, breaking through speed limitations, enabling six-dimensional measurement of large-range arbitrary contouring errors with improved dynamic performance assessment and reduced operational complexity and costs.
Implementation Method 1
a high-brightness short-time light-emitting unit (9) is fixed to grooves on both sides of the base (10)
Data Source
AI summary
A monocular vision six-dimensional measurement method for high-dynamic large-range arbitrary contouring error of a CNC machine tool of the present invention belongs to the field of dynamic error detection of machine tools, and relates to a six-dimensional measurement method for high-dynamic large-range arbitrary contouring error of a CNC machine tool using a monocular vision measurement technology with short-time stroboscopic illumination and a priori standard plate. The method designs a measurement fixture and a measurement system, and uses a monocular vision pose algorithm to improve both the visual measurable dimension and range of interpolated contour in combination with priori knowledge. In light of the principle of error distribution, a small field of view is used to enhance the measurement accuracy of the coded primitives in the images. Then, by traversing all the acquired images using the proposed method, we can obtain the six-dimensional motion contour; and the six-dimensional contouring error caused by the imperfect machine interpolation can be computed by comparing the measured contour with the nominal one. The method enhances the measurable dimension of the vision technology through the monocular vision pose algorithm in combination with a datum transformation method, and realizes the six-dimensional measurement of large-range arbitrary contouring error of the CNC machine tool under the small field of view.