MEMS Gyroscope Proof Mass Segmentation for 3-Axis Sensing
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Solution Overview
Problem
Existing MEMS gyroscope devices face challenges in measuring angular velocity in three axes with high accuracy and efficiency, particularly in maintaining a compact design while effectively suppressing common mode drive motion and ensuring orthogonal sense motion.
Innovation Solution
The MEMS gyroscope device incorporates two pairs of proof masses that move in perpendicular in-plane directions and orthogonal out-of-plane directions, utilizing pivot structures and common mode drive spring structures to achieve anti-phase motion, ensuring efficient sense motion parallel to electrodes and a single drive frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two pairs of proof masses are used to measure angular velocity in three axes, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The device divides the proof masses into two separate pairs, with each pair dedicated to measuring angular velocity around a specific axis. This segmentation allows independent optimization of each measurement pair while maintaining overall system functionality, resolving the contradiction between enhanced measurement capability and structural complexity
Solution Approach 2:
Each proof mass pair is designed to perform multiple functions: measuring angular velocity around its designated axis while also contributing to common mode vibration suppression. This multi-functionality reduces the need for additional separate components, thereby managing device complexity while improving measurement precision
2Reliability
If pivot structures are used to enable anti-phase motion, then common mode drive motion suppression is improved, but device complexity increases
Solution Approach 1:
The pivot structures are positioned asymmetrically relative to the proof masses, creating inherent mechanical advantage for generating anti-phase motion. This asymmetric configuration naturally suppresses common mode drive motion without requiring additional active control mechanisms, thereby improving reliability while limiting the increase in device complexity
3Measurement precision
If proof masses are driven in perpendicular in-plane directions, then orthogonality of sense motion is improved, but manufacturing precision requirements increase
Solution Approach 1:
The drive mechanisms for each proof mass pair are designed with locally optimized geometries that inherently guide motion along perpendicular in-plane directions. By incorporating directional guidance features directly into the local structure of each drive mechanism, the system achieves high sense motion orthogonality while reducing the overall manufacturing precision requirements through distributed local constraints
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 design enhances the accuracy and efficiency of angular velocity measurement in three axes, maintains a compact structure, and suppresses common mode drive motion, improving the overall performance of the MEMS gyroscope device.
Implementation Method 1
the first pair of proof masses are driven to slide back and forth past one another in a first in-plane directional axis, and the first pair of proof masses move in a third directional axis that is normal to the plane in response to angular velocity in the second directional axis
Implementation Method 2
the second pair of proof masses are driven to move toward and away from one another in a second in-plane directional axis that is perpendicular to the first directional axis, and the third and fourth proof masses move in the third directional axis in response to angular velocity in the first directional axis
Implementation Method 3
utilizing pivot structures and common mode drive spring structures to achieve anti-phase motion, ensuring efficient sense motion parallel to electrodes and a single drive frequency
Data Source
AI summary
A microelectromechanical system (MEMS) gyroscope device includes a substrate having a surface parallel to a plane; first and second proof masses driven to slide back and forth past one another in a first directional axis of the plane, where the first and second proof masses respectively have a first and second recess in a respective side closest to the other proof mass; a pivot structure coupled to the first proof mass within the first recess and to the second proof mass within the second recess; an anchor between the first and second recesses and coupled to a mid-point of the pivot structure; and third and fourth proof masses driven to move toward and away from one another in a second directional axis of the plane that is perpendicular to the first directional axis; where the proof masses move in response to angular velocity in one or more directional axes.