Axisymmetric Vibratory Gyroscope Scale Factor Calibration
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Solution Overview
Problem
Existing methods for calibrating the scale factor of axisymmetric vibratory gyroscopes are inadequate for operational use, as they lack precision and stability, especially in varying temperature environments, and often require additional sensors or disrupt the device's operation during calibration.
Innovation Solution
A method that involves measuring and storing an initial scale factor, then calculating a corrected scale factor using a modulated quadrature control signal or frequency-modulated amplitude control signal, allowing for real-time calibration while the device is in use, using a combination of amplitude and precession control signals to stabilize and correct the scale factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If temperature compensation methods (tabulation or polynomial calculation) are used to correct the scale factor, then temperature variations can be compensated, but aging effects are not taken into account and precision is inadequate
Solution Approach 1:
The patent applies preliminary action by performing calibration before operational use to establish an initial scale factor, then using real-time measurement of a measurable quantity during operation to calculate corrections. This preliminary calibration provides a baseline that accounts for manufacturing variations, and the subsequent real-time measurements capture aging and temperature effects that occur during actual use.
Solution Approach 2:
The patent implements feedback by continuously measuring a measurable quantity (such as resonant frequency or vibration characteristics) during operational use and using this measurement to calculate corrections to the scale factor. The computation unit receives the measured value, compares it against the stored initial value, and applies real-time corrections, creating a closed-loop system that adapts to changing conditions including temperature and aging.
2Measurement precision
If calibration is performed before operational use using appropriate means, then the scale factor can be determined, but the method cannot be carried out while the sensor is in use unless another sensor is available
Solution Approach 1:
The patent applies self-service by enabling the gyroscope to calibrate itself during operational use without requiring external calibration equipment or additional sensors. The system uses its own operational characteristics (measuring a measurable quantity from its own vibration or resonant behavior) to determine corrections to its scale factor, making the calibration process autonomous and continuously available during normal operation.
Solution Approach 2:
The patent ensures continuity of useful action by allowing calibration to occur during operational use rather than requiring a separate calibration phase. The gyroscope maintains its measurement function while simultaneously performing calibration, so the useful action of measuring angular velocity continues uninterrupted while the scale factor is being refined based on real-time measurements.
3Measurement precision
If frequency modulation measurement is used for calibration, then scale factor precision of 0.05% can be achieved, but the resonant frequency stability versus temperature is insufficient for outdoor thermal environments
Solution Approach 1:
The patent uses an intermediary approach by measuring a measurable quantity that is less sensitive to temperature variations than the resonant frequency itself. Rather than directly relying on resonant frequency measurements which are temperature-sensitive, the system measures a derived quantity (such as the ratio of amplitudes, phase differences, or other operational characteristics) that serves as a more stable intermediary for determining scale factor corrections in varying thermal environments.
4Measurement precision
If amplitude control signal processing with exponential evolution observation is used, then calibration can be performed, but the amplitude and scale factor vary significantly during calibration and the device is not operational
Solution Approach 1:
The patent applies partial action by using small, controlled modulations of the resonator's operating parameters rather than large amplitude variations. Instead of dramatically changing the amplitude to observe exponential evolution, the system uses subtle measurements of operational characteristics during normal operation, allowing calibration to proceed with minimal disruption to the device's operational state and maintaining continuous functionality.
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 precision and reliability of readings during operation by providing a stable and accurate scale factor correction, even in thermal environments, without rendering the device non-operational during calibration.
Implementation Method 1
The resonator is set into vibration at its resonant frequency by an amplitude control signal
Implementation Method 2
The orientation of the vibration is controlled by a precession control signal
Implementation Method 3
The excitation of mechanical vibrations of both the principle mode (antinode) and the precession mode (node) is produced by electrical oscillators (electromagnetic or electrostatic oscillators)
Data Source
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AI summary
The invention relates to gyroscopic instruments. The method for calibrating the scale factor of a hydraulic angular velocity sensor or an axisymmetric vibratory gyroscope, which method uses a control amplitude signal, a control precessional signal CP and a control quadrature signal CQ for exciting the vibration of a resonator on a resonant frequency, involves a first step of pre-calibration which consists of measuring and recording an initial scale factor and the value of an initial control signal, and a second step of measuring the value of the current control signal and establishing a scale factor SF that is corrected on the basis of a proportional relationship involving the initial scale factor SF°, the initial value of the control signal Y° and the current value of the control signal Y° according to the formula SF=SF°Y/Y°.