Ring Gyroscope Central Spring Structure for Vibration Robustness
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Solution Overview
Problem
Conventional MEMS gyroscope designs are prone to sensitivity issues due to parasitic modes that easily couple with external shocks and vibrations, leading to spurious responses and reduced accuracy in angular rate measurements.
Innovation Solution
A compact ring-type gyroscope structure with a specific central spring arrangement that positions the cos2θ resonance modes at the lowest frequencies, effectively eliminating parasitic modes and enhancing robustness against external mechanical excitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional ring structure is used, then the gyroscope can detect angular rate, but parasitic modes couple easily to external shocks and vibrations causing spurious responses
Solution Approach 1:
The patent changes the frequency parameters of the ring structure by introducing a central spring structure that modifies the resonance frequencies. The cos2θ modes are positioned at the lowest frequencies while parasitic modes are pushed to higher frequencies, creating a frequency separation that reduces coupling between operational modes and external vibrations.
Solution Approach 2:
The ring structure is segmented by introducing a central spring structure that divides the rigid ring into multiple connected segments. This segmentation allows independent control of different vibrational modes and enables the cos2θ modes to be isolated at specific frequencies while suppressing parasitic modes.
2Volume of moving object
If the gyroscope structure is made compact, then device size is reduced, but the Coriolis force becomes even smaller making signals minuscule compared to other electrical signals
Solution Approach 1:
The patent optimizes the dimensional parameters of the compact ring structure to maximize the Coriolis effect while maintaining small size. The central spring structure is designed with specific geometric parameters that enhance the coupling efficiency and signal amplitude despite the reduced scale of the device.
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 significantly reduces the gyroscope's sensitivity to external shocks and vibrations, improving the accuracy of angular rate measurements while maintaining a compact and lean design.
Implementation Method 1
The planar resonators are typically excited into a cos2θ resonance mode that exists as a degenerate pair of vibration modes at a mutual angle of 45°
Implementation Method 2
MEMS gyroscopes use the Coriolis effect to measure the angular rate. When a mass is moving in one direction and rotational angular velocity is applied, the mass experiences a force in orthogonal direction as a result of the Coriolis force
Data Source
Figure 1
Figure 2~3
Figure 4A~4C
AI summary
A ring gyroscope structure with central spring structure that prefers prefers 26-modes and makes them low in frequency. The flexing resonance modes that tend to couple to external mechanical excitation are clearly higher that the 26-modes. The described structure is thus very robust against external mechanical shocks and vibrations.