Calibration Method for Measurement Probe System Delay
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Solution Overview
Problem
Existing calibration methods for measurement probes on machines fail to accurately determine the relative delay between capturing machine position data and probe data, leading to synchronization issues and errors in coordinate measurements.
Innovation Solution
A method involving moving the measurement probe at a known speed along a path that includes changes in direction, allowing for the comparison of machine position data and probe data to determine the relative time delay, which is distinct from touch probe delays and accounts for system delays in both data capture processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing calibration methods are used for measurement probes, then the calibration process is simple, but the relative delay between machine position data and probe data capture cannot be accurately determined
Solution Approach 1:
The probe is moved along a predetermined path with known changes in direction before actual measurement. This preliminary movement pattern is designed to create identifiable transitions in the data that will later be used to calculate the relative delay between machine position and probe data capture, allowing accurate synchronization without complex real-time adjustments
Solution Approach 2:
The calibration method uses the captured machine position data and probe data to calculate the relative delay, then applies this delay information to synchronize the data streams. This feedback loop continuously refines the synchronization accuracy by comparing actual measured positions with expected positions and adjusting the timing alignment accordingly
2Manufacturing precision
If probe data and machine position data are captured without synchronization, then data capture is independent and simple, but coordinate measurements contain synchronization errors
Solution Approach 1:
A calibration path with predetermined direction changes is executed before actual measurement to establish the relative delay between data capture systems. This preliminary action allows the system to pre-calculate synchronization parameters, eliminating the need for time-consuming real-time adjustments during actual coordinate measurement operations
Solution Approach 2:
The calibration process introduces an intermediary step that calculates the relative delay between machine position data and probe data capture. This intermediary calculation acts as a mediator that aligns the two data streams in time, allowing accurate coordinate measurements to be obtained by simply applying the calculated delay correction rather than through complex real-time synchronization
Data Source
Figure 1
Figure 2a~2c
Figure 3~4
AI summary
A method is described for calibrating apparatus comprising a measurement probe (4) mounted on a machine, such as a machine tool. The machine is arranged to capture machine position data (x,y,z;70;80) indicative of the position of the measurement probe and the measurement probe is arranged to capture probe data (a,b,c;72;82) indicative of the position of a surface relative to the measurement probe (4). The measurement probe (4) is an analogue or scanning probe having a deflectable stylus (14). The first step of the method involves moving the measurement probe (4) at a known speed relative to an artefact (30;40,42) whilst capturing probe data (a,b,c;72;82) and machine position data (x,y,z;70;80). In particular, the measurement probe (4) is moved along a path that enables probe data (a,b,c;72;82) to be captured that is indicative of the position of one or more points on the surface of the artefact relative to the measurement probe (4). The path includes at least one change in the direction of probe movement that can be identified from the machine position data and the probe data. A second step of the method comprises comparing the machine position data (x,y,z;70;80) and the probe data (a,b,c;72;82) and determining from that data the relative delay in capturing probe data and machine position data (i.e. the so-called system delay).