MEMS Gyroscope Elastic Coupling Noise Rejection

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Solution Overview

Problem

Existing microelectromechanical gyroscopes are not perfectly immune to external acceleration noise and centrifugal acceleration, due to variations in mechanical characteristics of sensing masses and elastic elements, leading to poor noise rejection and potential errors in angular acceleration detection.

Innovation Solution

Mechanical coupling of sensing masses via elastic elements to couple their vibration modes, and a geometrical configuration of electrodes to compensate for centrifugal acceleration effects, allowing for improved noise rejection and reduced errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sensing masses are independently suspended via elastic elements, then the structure is simple and manufacturing is easy, but noise rejection is poor due to variations in mechanical characteristics

Engineering Contradiction:

Improvenoise rejectionVSAvoidstructural complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the suspension function with the coupling function by introducing elastic coupling elements that simultaneously connect sensing masses to each other and to the substrate. This combining of functions improves noise rejection through mechanical coupling while avoiding the need for completely separate suspension and coupling systems.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The elastic coupling elements act as intermediary components between the sensing masses and the substrate, providing both suspension and mechanical coupling. These intermediary elements enable the sensing masses to be mechanically coupled for noise rejection while still maintaining their suspension function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If sensing masses are mechanically coupled via elastic elements, then noise rejection is enhanced, but the device complexity increases

Engineering Contradiction:

Improvenoise rejectionVSAvoidnumber of elastic elements

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The elastic coupling elements are designed to perform multiple functions simultaneously: suspending the sensing masses from the substrate and providing mechanical coupling between adjacent sensing masses. This multi-functionality reduces the need for separate components and minimizes the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent optimizes the mechanical parameters of the elastic coupling elements, such as their stiffness and dimensions, to achieve effective noise rejection. By carefully selecting and tuning these parameters, the system achieves improved noise rejection without requiring excessive numbers of complex components.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If traditional electrode configuration is used, then manufacturing is simple, but centrifugal acceleration effects cause detection errors

Engineering Contradiction:

Improveangular acceleration detection accuracyVSAvoidelectrode configuration complexity

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent employs an asymmetric electrode configuration where electrodes are positioned at specific locations and oriented at particular angles to counterbalance centrifugal acceleration effects. This asymmetric arrangement creates electrical fields that compensate for the spurious signals generated during rotation, improving measurement precision.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The electrode configuration is designed in advance to produce electric fields that preemptively counteract the centrifugal acceleration effects. By pre-positioning electrodes and applying appropriate voltages, the system compensates for expected errors before they affect the measurement, maintaining detection accuracy.

Inventive Principle:

Principle #9Preliminary anti-action

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

Significantly enhances noise rejection by approximately 100 times and minimizes the impact of centrifugal acceleration, ensuring accurate detection of angular accelerations.

Implementation Method 1

first and second elastic coupling elements coupling the first sensing mass to the second sensing mass

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

first and second elastic anchorage elements anchoring the driving mass to a substrate

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 3

first and second elastic supporting elements, respectively suspending the first sensing mass and the second sensing mass within the driving mass

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS9278847B2Microelectromechanical gyroscope with enhanced rejection of acceleration noises

Publication Date: 2016.03.08 STMICROELECTRONICS SRL

AI summary

An integrated microelectromechanical structure is provided with a driving mass, anchored to a substrate via elastic anchorage elements and designed to be actuated in a plane with a driving movement; and a first sensing mass and a second sensing mass, suspended within, and coupled to, the driving mass via respective elastic supporting elements so as to be fixed with respect thereto in said driving movement and to perform a respective detection movement in response to an angular velocity. In particular, the first and the second sensing masses are connected together via elastic coupling elements, configured to couple their modes of vibration.