MEMS Gyroscope Decoupling Three-Axis Detection
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Solution Overview
Problem
Conventional MEMS gyroscopes for three-axis detection suffer from coupled sense modes and excessive errors due to superimposed errors between axes, leading to inaccurate angular velocity measurements.
Innovation Solution
A MEMS gyroscope design featuring a substrate with anchor and coupling structures, symmetrically arranged driving pieces, and decoupling mass blocks that form a rectangular frame, allowing independent detection of three axes by decoupling vibrations and reducing quadrature errors through differential drive and sense modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional MEMS gyroscope uses orthogonally arranged mass blocks for three-axis detection, then three-axis detection capability is achieved, but sense modes of the three axes become coupled and errors are superimposed resulting in excessive detection errors
Solution Approach 1:
The sensing unit is segmented into four independent sensing regions, each responsible for detecting angular velocity along one of the three axes. Each region contains specifically positioned mass blocks (X and Y mass blocks for in-plane detection, Z mass blocks for out-of-plane detection) that are spatially separated and independently coupled to the substrate through coupling structures. This segmentation prevents the sense modes of different axes from coupling with each other, allowing independent detection of three axes without error superposition.
Solution Approach 2:
Different regions of the sensing unit are designed with locally optimized structures tailored to specific detection needs. The X and Y mass blocks are positioned in avoiding spaces between coupling structures for in-plane angular velocity detection, while Z mass blocks are positioned at specific locations for out-of-plane detection. Each local region has customized coupling structures (first coupling beams, second coupling beams) that provide appropriate mechanical properties for that specific sensing function, thereby achieving high-precision three-axis detection without cross-axis interference.
2Adaptability or versatility
If four mass blocks are used for three-axis detection, then three-axis detection is enabled, but the structure causes sense modes to be coupled and errors to superimpose
Solution Approach 1:
The coupling structures serve multiple functions simultaneously: they provide mechanical support for the mass blocks, enable elastic coupling between mass blocks and substrate, create avoiding spaces for positioning, and provide pathways for signal transmission. The first coupling beams and second coupling beams not only support the X, Y, and Z mass blocks but also define the avoiding spaces and establish the mechanical connection to the substrate through anchor point structures. This multi-functionality reduces the need for additional separate components, thereby managing device complexity while achieving three-axis detection.
3Reliability
If conventional three-axis gyroscope design is used, then angular velocity detection is achieved, but quadrature errors and interference between axes increase detection errors
Solution Approach 1:
The coupling structures act as intermediaries between the mass blocks and the substrate, providing controlled elastic connections that isolate the sense modes of different axes. The first coupling beams connect the X and Y mass blocks to the substrate, while the second coupling beams connect the Z mass blocks to the substrate. These intermediary coupling structures prevent direct mechanical coupling between mass blocks of different axes, thereby eliminating quadrature errors and interference between axes while maintaining reliable angular velocity detection capability.
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 stability and accuracy of three-axis detection by reducing interference between axes, minimizing coupling errors, and enabling anti-phase motion, thereby improving the overall detection precision and bias stability.
Implementation Method 1
When an angular velocity Ω is applied, the MEMS oscillating gyroscope transfers energy and is switched to a sense mode due to the Coriolis effect, which indirectly drives a vibrating disk to oscillate out-of-plane.
Data Source
AI summary
A MEMS gyroscope for three-axis detection relates to the technical field of gyroscope and includes a substrate, a sensing unit elastically connected with the substrate, and a driving unit coupled with the sensing unit and driving the sensing unit to move. The substrate includes anchor point structures respectively located at four corners of the substrate and four coupling structures respectively elastically connected with the four anchor point structures. An avoiding space is formed between two adjacent coupling structures. The driving unit includes two driving pieces separately elastically connected with adjacent coupling structures. The two driving pieces are symmetrically arranged and are frame-shaped. The sensing unit includes four X and Y mass blocks, two Z mass blocks elastically connected with the driving pieces, and two decoupling mass blocks. The two decoupling mass blocks are elastically connected. The MEMS gyroscope is differentially driven, which realizes differential detection and reduces quadrature error.