MEMS Gyroscope Elastic Mass Segmentation for Signal Noise
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Solution Overview
Problem
MEMS gyroscopes face degraded signal-to-noise ratio and altered dynamic due to spurious components caused by constructional imperfections and misalignment of elastic constraints, leading to inaccurate detection of angular rates.
Innovation Solution
A microelectromechanical gyroscope design featuring a substrate with a stator sensing structure, a driving mass, a transduction mass, and a movable sensing structure, where the masses are elastically coupled to prevent unwanted movements and capacitively coupled to attenuate spurious displacements, ensuring that only Coriolis-induced displacements are effectively detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single mass is used in the gyroscope, then the device complexity is reduced, but spurious components from misalignment degrade the signal-to-noise ratio
Solution Approach 1:
The single mass is divided into multiple masses (first mass, second mass, third mass) connected by elastic constraints. This segmentation allows each mass to be precisely positioned and constrained independently, reducing misalignment errors and spurious components while maintaining overall structural coherence.
Solution Approach 2:
Elastic constraints are introduced as intermediary elements between the masses and substrate. These elastic constraints act as mediators that precisely control the motion of each mass, eliminating misalignment issues that would occur with direct rigid mounting, thereby improving the signal-to-noise ratio.
2Manufacturing precision
If elastic constraints are made more rigid to prevent misalignment, then manufacturing precision improves, but the dynamic response of the mass oscillation deteriorates
Solution Approach 1:
The elastic constraints are designed with specific mechanical properties that allow them to provide precise alignment (high effective stiffness in lateral directions) while maintaining appropriate oscillation characteristics (controlled stiffness in motion directions). By carefully selecting and tuning the elastic constraint parameters, both alignment precision and oscillation dynamics are optimized simultaneously.
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 design significantly improves the signal-to-noise ratio by attenuating spurious contributions, allowing for more accurate detection of angular rates with reduced interference from imperfections in the elastic constraints.
Implementation Method 1
The third mass is capacitively coupled to the stator sensing structure
Implementation Method 2
a first mass elastically coupled to the substrate and movable with respect to the substrate in a first direction
Implementation Method 3
When the gyroscope turns about an axis perpendicular to the driving direction and to the sensing direction at an angular rate, on account of the motion in the driving direction, the mass is subject to a Coriolis force and moves in the sensing direction
Data Source
AI summary
A microelectromechanical gyroscope includes: a substrate; a stator sensing structure fixed to the substrate; a first mass elastically constrained to the substrate and movable with respect to the substrate in a first direction; a second mass elastically constrained to the first mass and movable with respect to the first mass in a second direction; and a third mass elastically constrained to the second mass and to the substrate and capacitively coupled to the stator sensing structure, the third mass being movable with respect to the substrate in the second direction and with respect to the second mass in the first direction.