High Speed Contact Detector Trigger Timing
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Solution Overview
Problem
Current coordinate measuring machines (CMMs) face challenges in accurately determining the timing for coordinate measurements due to false triggers and signal delays, which can lead to inconsistent and inaccurate modeling of workpiece shapes.
Innovation Solution
A high-speed contact detector system that uses real-time probe characteristic measurements to generate trigger signals for coordinate measurements, eliminating false triggers and signal delays by setting a trigger time based on earlier measurements and accounting for processing delays, and optionally using a halt signal for confirmation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If contact detection characteristics are measured at a rapid pace (1000-2000 times per second), then the ability to capture contact events is improved, but false triggers and signal delays occur leading to measurement inaccuracies
Solution Approach 1:
The system performs preliminary measurements of contact detection characteristics and uses these earlier measurements to set the trigger time for coordinate measurement. This preliminary action allows the system to account for processing delays and signal transmission times before the actual measurement is taken, thereby eliminating false triggers and improving measurement accuracy while maintaining high detection speeds.
Solution Approach 2:
The system uses feedback from preliminary contact detection measurements to adjust and set the optimal trigger time for coordinate measurement. By continuously monitoring contact characteristics and using this information to determine when to trigger measurements, the system compensates for signal delays and processing times, resolving the contradiction between high-speed detection and measurement precision.
2Stability of the object's composition
If a threshold amount of deflection is used to determine when to measure coordinates, then consistency between measurements is improved, but false triggers occur due to signal delays and processing times
Solution Approach 1:
The system takes preliminary measurements of contact detection characteristics before the actual coordinate measurement is triggered. These preliminary measurements allow the system to establish the trigger time in advance, accounting for known processing and signal transmission delays. This ensures that the threshold-based triggering is more reliable and less prone to false triggers caused by timing issues.
Solution Approach 2:
The system creates a temporal copy or prediction of when the threshold will be reached based on preliminary measurements. Instead of waiting for the actual threshold crossing event, the system uses the preliminary data to predict and set the trigger time, effectively creating a virtual representation of the contact event that accounts for all processing delays before the actual measurement is taken.
3Productivity
If the probe is moved rapidly to probe multiple positions, then measurement efficiency is improved, but the timing for accurate coordinate capture becomes difficult to determine
Solution Approach 1:
For each probing position, the system performs preliminary contact detection measurements and uses these to set the precise trigger time for coordinate capture. This preliminary action at each position allows the system to maintain accurate timing even when moving rapidly between multiple positions, as each measurement point is independently optimized based on its own preliminary data.
Solution Approach 2:
The system maintains continuous contact detection measurements throughout the rapid probing process, ensuring that useful data is collected at every position without interruption. This continuous measurement approach allows the system to efficiently transition between multiple positions while maintaining accurate timing for each coordinate capture, as the preliminary measurements are continuously updated throughout the probing sequence.
Data Source
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AI summary
A workpiece is measured by a contact detector. The contact detector is moved relatively towards a workpiece. A characteristic of the contact detector that changes as the contact detector contacts the workpiece is measured at a plurality of times. A projected time when the characteristic of the contact detector will meet a predetermined threshold is extrapolated from the characteristic measured the plurality of times and using a processor of a computer. A trigger is set to measure coordinates of the workpiece at the projected time. Coordinates of the workpiece are measured at the projected time based on the set trigger.