Three-Axis MEMS Gyroscope Decoupling for Lower Sense-Mode Errors
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Solution Overview
Problem
Existing MEMS gyroscopes suffer from weak coupling among mass structures, leading to excessive errors due to superimposed sense modes of the three axes, which affect displacement ratio and stability.
Innovation Solution
A fully decoupled three-axis MEMS gyroscope design featuring symmetrically arranged mass blocks and decoupling structures, including inner and outer coupling rings, flexible beams, and decoupling members, allowing independent detection of XYZ axes with anti-phase vibration modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an orthogonally arranged four-mass three-axis gyroscope structure is used, then the gyroscope can detect angular velocity in three axes, but the sense modes of the three axes are coupled with each other causing excessive errors
Solution Approach 1:
The gyroscope is divided into four independent mass blocks (X1, X2, Y1, Y2) arranged symmetrically, with each mass block independently connected to the base through elastic beams. This segmentation allows each mass block to sense angular velocity in a specific direction independently, eliminating mode coupling while maintaining three-axis detection capability
Solution Approach 2:
The patent employs asymmetric arrangement of mass blocks and driving members, where mass blocks are positioned at specific locations and driving members are arranged in a non-uniform pattern. This asymmetric design creates independent sensing modes for each axis while maintaining the overall symmetric structure necessary for balanced detection performance
2Reliability
If mass blocks are elastically connected to the base, then the gyroscope can detect angular velocity, but the coupling between different modal motions increases errors
Solution Approach 1:
The patent introduces elastic beams as intermediary elements connecting mass blocks to the base, and driving members as intermediary structures that transmit driving forces. These intermediaries are strategically positioned to decouple modal motions while maintaining necessary mechanical connections, thereby reducing error propagation between different sensing modes
3Volume of moving object
If driving members are arranged close together, then the gyroscope structure is compact, but the coupling between adjacent driving members increases
Solution Approach 1:
The patent arranges driving members in a three-dimensional configuration around the central axis, with driving members positioned at different radial distances and angular positions. This spatial distribution in multiple dimensions allows compact overall structure while maintaining sufficient separation between adjacent driving members to minimize coupling effects
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 enhances stability, shock resistance, and detection accuracy by reducing coupling between mass blocks, minimizing orthogonal errors, and suppressing parasitic modes, thereby improving angular velocity detection precision.
Implementation Method 1
two X mass blocks symmetrically arranged in two of the avoiding intervals oppositely arranged and elastically connected to the coupling structure and the driving member
Implementation Method 2
When an angular velocity 2 is applied, the gyroscope transfers energy to the sensitive mode due to the Coriolis Effect, causing the vibrating disk to swing out-of-plane under relative drive
Data Source
AI summary
Provided is a fully decoupled MEMS gyroscope, including a base, a sensing unit elastically connected to the base, and a driving unit coupled with the sensing unit and driving the sensing unit to move. The base includes a coupling anchor point located at a center of a rectangle and a coupling structure elastically connected to the coupling anchor point. The driving unit includes four driving members located at inner positions of four corners of the rectangle. The sensing unit includes two X mass blocks symmetrically arranged in two of the avoiding intervals, two Y mass blocks symmetrically arranged in the other two of the avoiding intervals, four Z mass blocks elastically connected to the adjacent driving members and located at the four corners of the rectangle, and four Z detection decoupling members elastically connected to the adjacent Z mass blocks and elastically connected to each other around the rectangle.