Balanced Runners Synchronizing Anti-Phase Motion in MEMS Gyroscopes
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Solution Overview
Problem
Microelectromechanical systems (MEMS) gyroscopes face challenges in achieving synchronous, anti-phase motion of multiple proof masses while rejecting unwanted motion and acceleration sensitivity, leading to inaccuracies in rotation detection.
Innovation Solution
The implementation of linearly moving mechanical couplers, referred to as 'runners,' which couple multiple proof masses to enforce synchronous, anti-phase motion and inhibit in-phase motion, ensuring balanced operation and reduced acceleration sensitivity by moving in opposite directions to prevent net momentum and quadrature motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple proof masses are mechanically coupled together to provide synchronous motion, then rotation detection capability is improved, but acceleration sensitivity increases causing measurement inaccuracies
Solution Approach 1:
The patent employs proof masses arranged in anti-phase configurations where masses move in opposite directions. When acceleration occurs, the inertial forces generated by masses moving in opposite directions cancel each other out, effectively counterbalancing the harmful acceleration effects while maintaining synchronous motion for rotation detection.
Solution Approach 2:
The patent uses asymmetric coupling mechanisms and non-uniform mass distributions to create motion patterns where the coupled masses exhibit different acceleration responses. This asymmetry allows the system to differentiate between rotational motion (desired signal) and linear acceleration (harmful interference) by exploiting the different motion characteristics of the coupled masses.
2Measurement precision
If proof masses are coupled to enforce synchronous anti-phase motion, then rotation detection is improved, but unwanted in-phase motion and quadrature motion are not sufficiently rejected
Solution Approach 1:
The patent divides the coupled mass system into multiple independent proof masses that are mechanically linked through coupling elements. Each mass can move independently in anti-phase, and the coupling elements are designed to enforce anti-phase motion while naturally rejecting in-phase motion through their mechanical configuration, thereby maintaining stable synchronous motion patterns.
Solution Approach 2:
The patent introduces coupling elements as intermediary components between the proof masses. These couplers are designed to transmit motion in an anti-phase manner while blocking or rejecting in-phase motion and quadrature motion, acting as mechanical filters that enforce the desired motion pattern and improve rejection of unwanted motion modes.
3Measurement precision
If couplers are used to couple proof masses together, then synchronous anti-phase motion is achieved, but device complexity increases
Solution Approach 1:
The patent employs flexible coupling elements and thin-film mechanical structures to connect the proof masses. These flexible couplers provide the necessary mechanical linkage for enforcing anti-phase motion while maintaining a compact, integrated structure that minimizes device complexity. The flexible nature of these elements allows for simple fabrication processes and compact packaging.
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 solution enables MEMS gyroscopes to accurately detect rotation with reduced sensitivity to linear and angular accelerations, improving the accuracy and precision of rotation detection by ensuring anti-phase motion and momentum balance.
Implementation Method 1
a first coupler coupling the first and second proof masses together and configured to move linearly when the first proof mass moves in a first direction and the second proof mass moves in a second direction opposite the first direction
Implementation Method 2
a first proof mass coupled to the substrate by a first tether and configured to move linearly, and a second proof mass coupled to the substrate by a second tether and configured to move linearly
Implementation Method 3
When the gyroscope experiences rotation, the proof mass additionally moves along an axis different than the drive axis, sometimes referred to as the sense axis
Data Source
AI summary
Micromachined inertial devices are presented having multiple linearly-moving masses coupled together by couplers that move in a linear fashion when the coupled masses exhibit anti-phase motion. The couplers move in opposite directions of each other, such that one coupler on one side of the movable masses moves in a first linear direction and another coupler on the opposite side of the movable masses moves in a second linear direction opposite the first linear direction. The couplers ensure proper anti-phase motion of the masses.