Multi-Mode Coriolis Gyroscope Resonator with 32 Electrodes
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Solution Overview
Problem
MEMS gyroscopes face limitations in both resolution and range due to the constraints of analog-to-digital converters, and are sensitive to environmental factors like temperature and vibration, making them unsuitable for high-performance applications in weapon, space, and vehicle systems.
Innovation Solution
A Coriolis Vibratory Gyroscope (CVG) with a resonator exhibiting N-fold rotational symmetry, where N is a power of 2, and featuring 16 pairs of differential electrodes around its perimeter, capable of oscillating along n=1 and n=2 modes, with a control circuit that maintains phase differences and uses coarse sensitivity measurements as a bias for higher sensitivity readings, allowing for both high resolution and range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a gyroscope is designed to operate at high angular rates, then the range is improved, but the resolution deteriorates
Solution Approach 1:
The gyroscope employs multiple resonant modes (n=1 and n=2 modes) segmented across different frequency ranges. The n=1 modes handle lower angular rates with high resolution, while the n=2 modes extend the measurement range to higher angular rates. This segmentation allows the system to achieve both high resolution and wide range simultaneously by assigning different modes to different operational regimes.
2Ease of manufacture
If known MEMS gyroscopes are used, then the cost and simplicity are improved, but the environmental sensitivity worsens
Solution Approach 1:
The gyroscope utilizes a composite structure combining silicon resonator elements with specialized electrode configurations and multi-mode mechanical designs. This composite approach, while more complex than simple MEMS, provides enhanced environmental robustness through the synergistic combination of different structural components that collectively resist temperature and vibration effects better than conventional single-mode MEMS gyroscopes.
3Measurement precision
If high-resolution ADC is used to improve resolution, then the measurement precision is improved, but the device complexity and cost worsen
Solution Approach 1:
Instead of using a single high-resolution ADC, the system segments the measurement function across multiple resonant modes with different sensitivities. The n=1 modes provide high-resolution measurements for low angular rates, while n=2 modes cover higher rates. This segmentation allows the use of multiple lower-resolution ADCs or simpler conversion circuits, reducing overall system complexity and cost while maintaining high effective resolution through the multi-mode approach.
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
The CVG achieves a high resolution of 19 bits and a wide measurement range, reducing environmental sensitivity and enhancing performance in applications requiring precise angular rate detection.
Implementation Method 1
The Coriolis effect causes the vibrating object to for example exert a force on its support, and by measuring this force the rate of rotation can be determined.
Implementation Method 2
a control circuit that maintains phase differences and uses coarse sensitivity measurements as a bias for higher sensitivity readings
Data Source
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AI summary
An angular sensor, comprising a Coriolis vibratory gyroscope (CVG) resonator, capable of oscillating along a first pair of normal n=1 modes comprising a first normal mode and a second normal mode; and a second pair of normal n=2 modes comprising a third normal mode and a fourth normal mode; the sensor further comprising one drive electrode and one sense electrode aligned along an anti-nodal axis of each mode; and a pair of bias tune electrodes aligned with an anti-nodal axis of each mode if no drive and sense electrode pair is aligned with said anti-nodal axis.