Two-Axis MEMS Gyroscope Using Orthogonal Proof Masses

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Solution Overview

Problem

Inertial measurement systems require multiple expensive and sensitive gyroscopes to measure rotation about three orthogonal axes, leading to high complexity and cost.

Innovation Solution

A two-axes MEMS gyroscope system utilizing two proof masses, drive and sense components, and Coriolis sense electrodes, with a processing device to determine rotation rates about two orthogonal axes, reducing the need for multiple sensors by using comb capacitors and modulation frequencies to demodulate signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If three separate gyroscopes are used to measure rotation about three orthogonal axes, then measurement completeness is improved, but device complexity and cost increase

Engineering Contradiction:

Improvemeasurement completenessVSAvoidsensor complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple gyroscope functions into a single integrated device. One gyroscope measures rotation about the Z-axis while another measures rotation about the Y-axis, and these are integrated with additional proof masses and sensing elements to potentially measure multiple axes simultaneously, reducing the total number of separate sensors needed from three to two or fewer

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The gyroscope device is designed to perform multiple measurement functions. The first gyroscope can measure rotation about the Z-axis, and the second gyroscope can measure rotation about the Y-axis, with the ability to potentially measure rotation about the X-axis as well, making each device universal for multiple axes rather than dedicated to a single axis

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If three separate gyroscopes are used to measure rotation about three orthogonal axes, then measurement completeness is improved, but cost increases

Engineering Contradiction:

Improvemeasurement completenessVSAvoidsystem cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent employs MEMS (Micro-Electro-Mechanical Systems) technology which uses inexpensive materials and fabrication processes. The proof masses, drive components, and sense electrodes are manufactured using standard semiconductor fabrication techniques that are significantly cheaper than traditional mechanical gyroscopes, enabling cost-effective production of multi-axis measurement systems

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If multiple expensive and sensitive gyroscopes are used, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improverotation measurement precisionVSAvoidsensor complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical gyroscope systems with MEMS-based gyroscopes that use electrostatic drive and sense components. The mechanical rotation sensing is substituted with capacitance changes detected by electric fields, reducing mechanical complexity while maintaining measurement precision through electrical sensing mechanisms

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating parameters and detection methods. Instead of measuring mechanical rotation directly with traditional gyroscopes, the system uses proof masses that respond to Coriolis forces, detects motion through capacitance changes, and processes signals through electronic modulation and demodulation at specific frequencies, achieving precision through electrical parameter changes rather than mechanical measurements

Inventive Principle:

Principle #35Parameter changes

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 system effectively measures rotation rates about two orthogonal axes with reduced complexity and cost, leveraging MEMS technology to simplify sensor configurations and lower expenses.

Implementation Method 1

two Coriolis sense electrodes sensitive to out-of-plane proof mass motion, two Coriolis sense electrodes sensitive to in-plane proof mass motion

Methodology Applied

Scientific EffectCoriolis force: Coriolis Force

Implementation Method 2

The two drive components and the two drive sense components form comb capacitors with respective proof masses

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS7703324B2MEMS tuning fork gyro sensitive to rate of rotation about two axes

Publication Date: 2010.04.27 HONEYWELL INTERNATIONAL INC

AI summary

A two-axes rate sensing MEMS system. The system includes two proof masses, two drive components, two drive sense components, two orthogonal sets of substrate electrodes, and a processing device. The processing device is in signal communication with the two proof masses, the two sense components, or the two sets of substrate electrodes. The processing device determines the rate of rotation about two orthogonal axes based on signals received from the two proof masses, the two sense components, or the two substrate electrodes. Rotation about one axis will induce proofmass motion in the plane of the substrate. Rotation about an orthogonal axis will induce proofmass motion out-of-plane of the proofmasses. The sensing scheme independently detects these proof mass motion, which can infer rate of rotation.