Micromachined Gyroscope Symmetrical Assemblies Vibration Control
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Solution Overview
Problem
Existing micromachined gyroscopes with a tuning fork architecture are sensitive to attachment conditions and external perturbations due to unbalanced detection modes, while double tuning-fork designs are larger, more complex, and prone to parasitic vibration modes from etching defects.
Innovation Solution
A gyroscope with two symmetrical moving assemblies connected by a coupling structure, where each assembly has two moving elements, allowing vibration energy transfer in orthogonal directions, with a second moving element connected to prevent movement in one direction and linked via flexible beams for balanced detection, reducing size and complexity while controlling vibration modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a double tuning-fork design is used to achieve dynamic balance, then sensitivity and robustness improve, but device size and structural complexity increase
Solution Approach 1:
The gyroscope structure is divided into two separate moving assemblies (first and second), each containing tuning fork elements. This segmentation allows independent optimization of each assembly while achieving overall dynamic balance, reducing the complexity compared to a single large double tuning-fork structure.
Solution Approach 2:
Two moving assemblies are combined in a symmetrical configuration around the sensitive axis. The first and second moving assemblies work together to achieve dynamic balance, merging their functions to improve sensitivity while maintaining manageable complexity through symmetry.
2Reliability
If a double tuning-fork design is used to counterbalance detection movement, then robustness against perturbations improves, but manufacturing cost and complexity increase
Solution Approach 1:
Within each moving assembly, the tuning fork elements are positioned asymmetrically relative to the sensitive axis (at different radial distances). This asymmetric positioning within symmetrical assemblies creates the necessary dynamic balance, achieving robustness without requiring the more complex double tuning-fork structure.
Solution Approach 2:
The radial positioning parameters of the tuning fork elements are optimized differently for each assembly (first assembly at one radial distance, second assembly at another). By changing these positional parameters, dynamic balance is achieved with simpler manufacturing requirements compared to identical double tuning-fork structures.
3Ease of manufacture
If traditional tuning fork architecture is used, then manufacturing simplicity is maintained, but detection mode becomes unbalanced and sensitive to attachment conditions
Solution Approach 1:
The second moving assembly acts as a counterweight to the first moving assembly, with elements positioned to create opposing moments around the sensitive axis. This counterbalancing approach achieves detection balance while maintaining the manufacturing simplicity of standard tuning fork architectures.
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 gyroscope achieves balanced detection with increased sensitivity and reduced parasitic modes, making it less expensive and easier to produce, while maintaining precise velocity measurements and robustness against etching defects.
Implementation Method 1
When the gyroscope rotates at a certain angular velocity about its sensitive axis, the composition of the forced vibration with the angular rotation vector generates, by the Coriolis effect, forces that set the moving assemblies into natural vibration perpendicular to the excitation vibration and to the rotation axis.
Data Source
AI summary
A gyroscope having a vibrating structure, produced by micromachining in a thin planar wafer, the gyroscope including two symmetrical moving assemblies that are coupled by a coupling structure connecting the two assemblies so as to allow mechanical vibration energy to be transferred between them, each moving assembly including a first moving element connected to the coupling structure and able to vibrate with two degrees of freedom in orthogonal directions Ox and Oy of the plane of the wafer, and a second moving element adjacent the first moving element, capable of vibrating only in the Oy direction and connected to the first moving element via linkage element, wherein the linkage element allow the transmission, in phase opposition, to the second moving element of the vibration movement of the first moving element in the Oy direction.