CMM Probe Update-Rate Switching to Reduce Thermal Drift
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Solution Overview
Problem
Coordinate measuring machines (CMMs) experience power-on drift due to thermal instability of measuring probes, leading to measurement errors during the warm-up period, which is time-consuming and undesirable for efficient measurement operations.
Innovation Solution
A measuring system with a measuring probe that switches between a slower and faster update rate to reduce power-on drift by lowering electrical power dissipation, using a controller to switch between modes based on proximity to the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the measuring probe operates with a high update rate continuously, then measurement precision and response time are improved, but power consumption increases causing thermal drift and measurement errors
Solution Approach 1:
The patent applies dynamics by making the update rate adjustable rather than fixed. The control circuit dynamically changes the update rate based on the probe's operational state: using a first update rate during movement modes and a second update rate during measurement modes. This dynamic adjustment optimizes the balance between measurement precision and power consumption, preventing thermal drift while maintaining accuracy when needed.
Solution Approach 2:
The patent changes the operational parameter (update rate) based on the operational mode. The control circuit receives mode indication signals and adjusts the update rate parameter accordingly - switching between a higher update rate for measurements and a lower update rate for movement. This parameter change reduces power consumption during non-measurement periods, preventing thermal drift while preserving measurement precision when required.
2Stability of the object's composition
If the measuring probe operates with a low update rate to reduce power consumption, then thermal stability is improved, but measurement response time and precision deteriorate
Solution Approach 1:
The system dynamically adjusts the update rate based on real-time operational mode detection. When the probe is in measurement mode (contact with workpiece), the control circuit switches to a higher second update rate to ensure fast response and high precision. When in movement mode, it switches to a lower first update rate to conserve power and maintain thermal stability. This dynamic switching resolves the contradiction between stability and speed.
Solution Approach 2:
The update rate parameter is changed based on operational requirements. The control circuit monitors the operational mode and adjusts the update rate parameter - using a lower value for thermal stability during movement and a higher value for fast response during measurement. This conditional parameter change ensures both thermal stability and measurement responsiveness are maintained at appropriate times.
3Measurement precision
If the measuring probe uses a single high update rate for all operations, then measurement accuracy is maintained, but power consumption increases causing warm-up drift
Solution Approach 1:
The patent implements periodic action by alternating between different update rates based on operational phases. Instead of continuously operating at high update rate, the system periodically switches to a lower update rate during movement modes, reducing power consumption and minimizing warm-up drift. When measurement mode is detected, it returns to the higher update rate to ensure accuracy. This periodic switching between rates prevents continuous high power consumption while maintaining measurement accuracy when needed.
Solution Approach 2:
The update rate parameter is conditionally changed based on operational mode. The control circuit receives mode indication signals and adjusts the parameter - using a lower update rate during movement to reduce power consumption and warm-up drift, and a higher update rate during measurement to maintain accuracy. This conditional parameter adjustment resolves the contradiction between maintaining accuracy and reducing warm-up time.
4Speed
If the measuring probe operates continuously at high power to maintain readiness, then response time is improved, but thermal drift and measurement errors increase
Solution Approach 1:
The system dynamically adjusts operational intensity based on detected mode. The control circuit monitors for measurement mode conditions and only activates the high update rate (high power mode) when actually needed for measurements. During movement modes, it operates at low power with reduced update rate. This dynamic response ensures fast response time during measurements while maintaining reliability by avoiding thermal drift during non-measurement periods.
Solution Approach 2:
The update rate parameter is changed based on operational necessity. The control circuit switches to a higher parameter value (faster update rate) only during measurement modes when response time is critical, and uses a lower parameter value during movement modes to reduce power consumption and prevent thermal drift. This conditional parameter adjustment maintains both response time and measurement reliability.
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
Reduces power-on drift and measurement errors by optimizing power consumption and maintaining thermal stability, enabling efficient and accurate measurement operations.
Implementation Method 1
at least one detection element capable of detecting a movement of the contact portion as corresponding to a contact with a workpiece
Implementation Method 2
a signal processing circuit for processing an output of the detection element. The signal processing circuit processes a sensor signal from the detection element to output a measurement signal
Data Source
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AI summary
A measuring system includes a measuring probe with a contact portion that contacts a workpiece to be measured. The measuring probe operates with a first update rate during at least part of a moving mode, wherein the moving mode includes movement of the measuring probe such that the contact portion is moved away from the workpiece and/or is moved at a distance from the workpiece that is equal to or greater than a threshold distance. The measuring probe operates with a second update rate (i.e., which is faster than the first update rate) during at least part of a measuring mode, wherein the measuring mode includes movement of the measuring probe such that the contact portion is moved toward the workpiece for obtaining a measurement. In various implementations, the combined use of the first and second update rates effectively reduces power-on drift of the measuring probe.