MEMS Gyroscope Anti-Phase Drive and Coupling Link Vibration Rejection
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Solution Overview
Problem
Existing multi-axis MEMS gyroscopes face challenges in accurately measuring angular velocities due to external forces like linear accelerations and vibrations, which cause measurement errors through Coriolis forces and cross-coupling of drive and sense forces.
Innovation Solution
A MEMS gyroscope design featuring a shared drive system with first and second drive masses driven in anti-phase, coupled with in-plane and out-of-plane proof masses. The out-of-plane proof masses are connected via a coupling link to reject linear and rotational vibrations, enhancing vibration rejection and shock robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a shared drive system with coupled proof masses is used to reduce device complexity, then device complexity is reduced, but measurement precision deteriorates due to cross-coupling of drive and sense forces between different sense axes
Solution Approach 1:
The gyroscope structure is segmented into independent sense axes with separate drive and sense structures for each axis. This segmentation isolates the drive and sense movements of different sense axes, preventing cross-coupling interference while maintaining overall system functionality. Each sense axis operates independently with its own proof masses and sensing elements.
Solution Approach 2:
The drive and sense structures are extracted and separated into distinct functional components for each sense axis. The drive structure for one sense axis is separated from the sense structure of another axis, eliminating the cross-coupling effect. This extraction allows each axis to be optimized independently for its specific function.
2Area of stationary object
If proof masses are coupled within a common structure to reduce device area, then device area is reduced, but measurement precision deteriorates due to cross-coupling of drive and sense forces between different sense axes
Solution Approach 1:
The common structure is segmented into separate functional zones for each sense axis, with dedicated drive and sense regions. This segmentation allows the proof masses to be spatially separated into distinct groups for different sense axes, reducing cross-coupling while maintaining compact overall device area through efficient spatial arrangement.
Solution Approach 2:
The structure transitions from a planar two-dimensional layout to a three-dimensional configuration, utilizing vertical stacking and out-of-plane arrangements. This dimensional change allows drive and sense structures of different sense axes to be separated in the third dimension, reducing cross-coupling effects while maintaining a compact footprint area.
3Device complexity
If a shared drive system is used to reduce device complexity, then device complexity is reduced, but reliability deteriorates due to susceptibility to external vibrations and linear accelerations
Solution Approach 1:
The shared drive system is segmented into independent drive subsystems for each sense axis, with separate drive proof masses and actuation mechanisms. This segmentation isolates the vibration response of each axis, preventing vibration from one axis from affecting the measurement accuracy of other axes, thereby improving reliability under vibrational conditions.
Solution Approach 2:
Vibration isolation mechanisms and decoupling elements are introduced as intermediary components between the drive structures and sense structures. These intermediaries act as vibration filters and isolation elements, protecting the sensitive sense measurements from external vibrations and linear accelerations while allowing the drive functionality to operate.
4Area of stationary object
If proof masses are coupled within a common structure to reduce device area, then device area is reduced, but reliability deteriorates due to susceptibility to external vibrations and linear accelerations
Solution Approach 1:
The coupled proof mass structure is segmented into separate proof mass groups for different sense axes, with isolation elements between them. This segmentation reduces the transmission of vibration forces between axes while maintaining the compact area benefits of the coupled structure through efficient spatial arrangement of the segmented components.
Solution Approach 2:
The proof masses are arranged in a three-dimensional configuration rather than a planar layout, utilizing vertical separation and out-of-plane positioning. This dimensional arrangement reduces the coupling of vibration forces between different sense axes while maintaining a compact device footprint, improving reliability under vibration.
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 proposed design effectively rejects external vibrations and balances drive oscillations, improving the accuracy and precision of angular velocity measurements by decoupling drive motion from sense motion and reducing the impact of unwanted vibrations.
Implementation Method 1
a first drive mass that is driven in a first direction along a first axis and a second drive mass that is driven parallel to the first axis in anti-phase to the first drive mass
Implementation Method 2
responsive to an angular velocity about an out-of-plane axis to cause a first in-plane Coriolis force perpendicular to the first drive motion
Implementation Method 3
a coupling link between the first out-of-plane proof mass and the second out-of-plane proof mass. The coupling link causes the first out-of-plane proof mass and the second out-of-plane proof mass to reject a linear vibration and a rotational vibration
Data Source
AI summary
A MEMS gyroscope may have first and second drive masses configured to be driven in anti-phase. The gyroscope also includes first and second out-of-plane proof masses coupled to the first and second drive masses, respectively. The first and second out-of-plane proof masses may be driven in anti-phase to each other. The first and second out-of-plane proof masses may each include a driven mass and a sense mass, and may be responsive to an angular velocity about an out-of-plane axis to cause a respective in-plane Coriolis forces perpendicular to their respective drive motions. The gyroscope also includes a coupling link between the sense masses of first and second out-of-plane proof masses, which results in rejection of undesired vibrations.