CMM Probe Distance Adjustment Using Beam-Pattern Feedback
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Solution Overview
Problem
Current methods for controlling the distance between a non-contact probe head of a Coordinate Measuring Machine (CMM) and a work piece are inefficient, especially during manual measurements of unknown work pieces, leading to inaccurate and time-consuming data collection.
Innovation Solution
The method involves providing nominal steering commands and probe distance target data to automatically control the distance between the probe head and the work piece. This is achieved by projecting a primary measuring beam, acquiring a secondary measuring beam pattern, and deriving surface information and probe distance information in real-time to adjust the distance accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If manual steering commands are used to control the probe head movement, then flexibility in measuring unknown work pieces is improved, but measurement accuracy and consistency deteriorate due to operator variability
Solution Approach 1:
The system implements feedback by continuously deriving probe distance information from the secondary measuring beam pattern and comparing it with target distance data. Distance adjustment steering commands are generated based on this feedback to maintain optimal probe-work piece distance, eliminating operator variability while preserving manual steering flexibility for unknown geometries.
Solution Approach 2:
The patent replaces manual mechanical steering with an automated optical measurement and control system. The probe head position and distance are controlled through automated derivation of distance information from beam patterns and generation of steering commands, substituting human operator control with an automated optical-mechanical system that maintains both flexibility and precision.
2Device complexity
If the probe head distance to the work piece is not automatically controlled, then device complexity is reduced, but measurement consistency and quality deteriorate
Solution Approach 1:
The system performs self-service by automatically deriving probe distance information from the acquired secondary measuring beam pattern without requiring external distance sensors or complex additional hardware. The control system uses the measurement data itself to determine distance and generate adjustment commands, maintaining measurement consistency while minimizing added device complexity.
3Measurement precision
If full surface measurement data is processed in real-time to control probe distance, then measurement accuracy is improved, but processing time and productivity deteriorate
Solution Approach 1:
The system extracts only the essential distance information from the complete secondary measuring beam pattern data. Instead of processing the entire surface measurement dataset, the control system derives probe distance information by analyzing specific characteristics of the beam pattern, thereby maintaining accurate distance control while significantly reducing processing time and preserving productivity.
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 enhances the accuracy, robustness, and efficiency of CMM measurements by maintaining optimal probe head-work piece distance, even for complex geometries, thereby reducing operator effort and measurement time.
Implementation Method 1
projecting a primary measuring beam pattern onto the work piece, wherein the primary measuring beam pattern providing a plurality of measurement points, and acquiring a secondary measuring beam pattern, wherein the secondary measuring beam pattern originating from an interaction of the primary measuring beam with the work piece
Data Source
Figure 1a~1b
Figure 1c~2
Figure 3
AI summary
The invention relates to method for controlling a distance between a non-contact measurement probe head of a CMM and a work piece during a measurement. The method comprises the steps of 1.) providing steering commands to steer the work piece and/or the probe head through a measuring path comprising measuring positions, 2.) performing at a measuring position a measuring step comprising a.) providing distance adjustment steering commands to set the distance between the probe head and the work piece, b.) projecting a primary measuring beam pattern onto the work piece, c.) acquiring a secondary measuring beam pattern originating from an interaction of the primary measuring beam with the work piece, d.) deriving surface information based on the secondary measuring beam pattern, e.) deriving information regarding the distance between the probe head and the work piece, f.) deriving a distance deviation based on a distance target the derived distance information, g.) providing the distance deviation for a distance adjustment performed at a subsequent measuring position.