Online Phase Calibration for Drift-Stable Clearance Sensing
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Solution Overview
Problem
Existing phase calibration techniques for sensor systems, such as those used in measuring clearance between rotating components like turbine blades, face inaccuracies due to geometry changes and are not adaptable for online calibration, especially in high-accuracy applications requiring precise phase references.
Innovation Solution
The implementation of online relative and absolute phase calibration systems that utilize multiple excitation signals, phase detectors, and processors to determine phase-to-voltage transfer functions, allowing for real-time calibration and compensation for environmental and component drifts without relying on absolute phase references.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If factory calibration techniques are used, then initial measurement accuracy is achieved, but the system cannot adapt to online calibration needs and drift occurs during operation
Solution Approach 1:
The system transitions from static factory calibration to dynamic online calibration by continuously monitoring phase measurements and automatically adjusting calibration parameters during operation. The calibration system adapts to changing conditions in real-time, maintaining accuracy without requiring manual intervention or shutdowns.
Solution Approach 2:
The patent implements feedback mechanisms where phase measurement data is continuously analyzed and fed back to the calibration system. This feedback loop enables automatic detection of drift and triggers recalibration operations, ensuring the system maintains measurement precision while adapting to operational changes.
2Measurement precision
If phase references are injected for calibration, then phase accuracy is improved, but the system becomes unsuitable for very high accuracy applications requiring 0.1 degree precision
Solution Approach 1:
The patent removes the phase reference injection component from the calibration system. Instead of relying on external phase references that limit accuracy to approximately 1 degree, the system extracts calibration information directly from the sensor measurements themselves, enabling sub-0.1 degree precision by eliminating the reference-induced error source.
Solution Approach 2:
The calibration system performs self-calibration by using the sensor's own measurements as the calibration source. The system extracts calibration data from the phase measurements without requiring external phase references, enabling the sensor to calibrate itself and achieve very high accuracy limited only by the sensor's intrinsic precision.
3Measurement precision
If controlled clearance change calibration is performed, then system gain is measured, but exhaustive calibration steps are required and variations after factory calibration are not accounted for
Solution Approach 1:
The patent performs calibration continuously at a reduced level during normal operation rather than requiring exhaustive periodic calibration steps. By continuously monitoring phase measurements and performing incremental calibration adjustments, the system maintains accuracy without requiring time-consuming complete recalibration cycles, thus reducing calibration time while preserving measurement precision.
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
Enables accurate and adaptive phase calibration during operation, independent of component aging, temperature, and environmental effects, ensuring high precision and reliability in clearance measurements.
Implementation Method 1
at least two sensors coupled to respective ones of the at least one excitation source via a transmission line
Implementation Method 2
a capacitance probe employed to measure distance between two objects. The probe is located on one of the objects and measures a capacitance with respect to the other object
Implementation Method 3
each of the two phase detectors are configured to output a respective voltage representing a phase difference between respective ones of the reflected signals and respective ones of the excitation signals
Data Source
AI summary
A system for online relative phase calibration is provided. The system includes at least one excitation source configured to generate multiple excitation signals. The system also includes at least two sensors coupled to respective ones of the at least one excitation source via a transmission line, wherein the two sensors are configured to receive respective ones of the excitation signals. The system further includes at least two phase detectors configured to receive at least two reflected signals from the two sensors via the transmission line, wherein each of the two phase detectors are configured to output a respective voltage representing a phase difference between respective ones of the reflected signals and respective ones of the excitation signals. The system also includes a switch coupled to the sensors and the phase detectors, the switch configured to switch the phase detectors between the sensors at a pre-determined switching interval. The system further includes a calibration module coupled to the phase detectors, wherein the calibration module is configured to receive and process the respective voltage from the at least two phase detectors to generate respective calibrated voltage signals, wherein the calibration module is further configured to and match the calibrated voltage signals of each of the phase detectors.