Toroidal Ring Gyroscope with Distributed Suspension for High Q-Factor
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Solution Overview
Problem
Achieving high-Q factor in compact micromachined gyroscopes is challenging due to support losses, thermo-elastic dissipation, and viscous damping, limiting their performance in rate sensitivity and stability.
Innovation Solution
A toroidal ring gyroscope with a robust outer perimeter anchor and distributed suspension system, which concentrates vibrational energy inward and prevents it from propagating to the outer anchor, combined with parametric drive for amplitude control to reduce drifts, enhancing scale factor stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a compact micromachined gyroscope is designed, then the device size is reduced, but the Q-factor decreases due to support losses and thermo-elastic dissipation
Solution Approach 1:
The gyroscope is segmented into a proof mass portion and a suspension system with multiple arms, where each arm is independently supported at its base. This segmentation isolates the vibrational energy to specific regions and reduces energy loss through the support structures, achieving high Q-factor (>100,000) in a compact device.
Solution Approach 2:
The suspension arms are designed with varying properties along their length, with the proof mass concentrated at the distal end and the support located at the base. This local differentiation optimizes the distribution of vibrational energy, confining it to the proof mass region while minimizing losses at the support points, thereby maintaining high Q-factor in a small volume.
2Measurement precision
If a high-Q factor is achieved in a compact gyroscope, then rate sensitivity improves, but the device complexity increases due to distributed suspension system
Solution Approach 1:
The gyroscope employs asymmetric suspension arms with different orientations and properties, where each arm is supported independently at its base rather than through a central anchor. This asymmetric configuration reduces coupling between vibrational modes and minimizes support losses, achieving high Q-factor and rate sensitivity while maintaining manageable device complexity.
3Stability of the object's composition
If parametric drive is used for amplitude control, then scale factor stability improves, but the device complexity increases
Solution Approach 1:
The gyroscope employs parametric drive with periodic modulation of the drive amplitude at twice the resonant frequency to maintain constant oscillation amplitude. This periodic action compensates for amplitude drift and improves scale factor stability (by 14 times according to the patent) while using a relatively simple control mechanism that modulates the drive signal rather than requiring complex mechanical adjustments.
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 solution achieves a Q-factor of over 100,000 at a compact size, improving scale factor stability by 14 times and maintaining better than 20 ppm stability without compensation or temperature stabilization, suitable for high-g environments.
Implementation Method 1
a capacitive gap between the electrode assembly and the innermost portion of the distributed suspension system, the electrode assembly further configured for driving the distributed suspension system into oscillation by electrostatic forces
Implementation Method 2
The vibrational energy in the introduced design is concentrated towards the innermost ring, and the device is anchored at the outer perimeter. The distributed support structure prevents vibrational motion propagating to the outer anchor, which helps trap the vibrational energy within the gyroscope and provides a Q-factor of >100,000
Implementation Method 3
Coriolis Vibratory Gyroscopes (CVGs) can be divided into two broad categories based on the gyroscope's mechanical element: Degenerate mode gyroscopes which have x-y symmetry (Δf=0 Hz ideal)
Data Source
AI summary
A toroidal ring gyroscope with a robust outer perimeter anchor and a distributed suspension system. The vibrational energy in the design is concentrated towards the innermost ring, and the device is anchored at the outer perimeter. The distributed support structure prevents vibrational motion propagating to the outer anchor, which helps trap the vibrational energy within the gyroscope and provides a Q-factor of >100,000 at a compact size of 1760 μm. Due to the parametric pumping effect, energy added to each mode is proportional to the existing amplitude of the respective mode. As a result, errors associated with finding the orientation of the standing wave and x-y drive gain drift are bypassed. The toroidal ring gyroscope can be fabricated using any standard silicon on insulator process. Due to the high Q-factor and robust support structure, the device can potentially be instrumented in high-g environments that require high angular rate sensitivity.