Dual-axis tuning fork gyroscope with coupled resonant structure

Solution Overview

Problem

Existing MEMS gyroscopes require multiple resonant structures to sense yaw rate in two orthogonal directions, leading to manufacturing variations in resonance frequencies and increased chip area and power consumption due to the need for separate detecting and control circuitry.

Innovation Solution

A dual-axis yaw rate sensing unit utilizing a single mechanical resonant structure with four open-ended tuning forks mechanically coupled together, allowing simultaneous sensing of yaw rate in two axial directions with a common frequency and phase, and employing capacitive, piezoelectric, or piezoresistive elements for driving and sensing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If two individual vibrating gyroscopes are placed on the same chip to sense yaw rate in two orthogonal directions, then the sensing capability in multiple directions is achieved, but the chip area and power consumption increase due to separate detecting and control circuitry

Engineering Contradiction:

Improvesensing capability in multiple directionsVSAvoidchip area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent merges two separate vibrating gyroscope structures into a single integrated resonant structure with four tuning forks arranged in two orthogonal pairs. This consolidation allows the system to sense yaw rate in both X and Y directions using one unified mechanical structure, thereby reducing chip area while maintaining multi-directional sensing capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single resonant structure with four tuning forks serves multiple functions simultaneously: it acts as both the driving structure and the sensing structure for two orthogonal directions. The structure is designed to vibrate in both X and Y directions, enabling one structure to perform the work of two separate gyroscopes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If two individual vibrating gyroscopes are placed on the same chip to sense yaw rate in two orthogonal directions, then the sensing capability in multiple directions is achieved, but the power consumption increases due to separate detecting and control circuitry

Engineering Contradiction:

Improvesensing capability in multiple directionsVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by stationary object

Solution Approach 1:

The patent merges two separate vibrating gyroscope structures into a single integrated resonant structure with four tuning forks arranged in two orthogonal pairs. This consolidation allows the system to sense yaw rate in both X and Y directions using one unified mechanical structure, thereby reducing chip area while maintaining multi-directional sensing capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single resonant structure with four tuning forks serves multiple functions simultaneously: it acts as both the driving structure and the sensing structure for two orthogonal directions. The structure is designed to vibrate in both X and Y directions, enabling one structure to perform the work of two separate gyroscopes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If two individual vibrating gyroscopes are placed on the same chip to sense yaw rate in two orthogonal directions, then the sensing capability in multiple directions is achieved, but separate detecting and control circuitry are required

Engineering Contradiction:

Improvesensing capability in multiple directionsVSAvoiddetecting and control circuitry

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges two separate vibrating gyroscope structures into a single integrated resonant structure with four tuning forks arranged in two orthogonal pairs. This consolidation allows the system to sense yaw rate in both X and Y directions using one unified mechanical structure, thereby reducing chip area while maintaining multi-directional sensing capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single resonant structure with four tuning forks serves multiple functions simultaneously: it acts as both the driving structure and the sensing structure for two orthogonal directions. The structure is designed to vibrate in both X and Y directions, enabling one structure to perform the work of two separate gyroscopes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Area of stationary object

If a single resonant structure is used to sense yaw rate in two orthogonal directions, then chip area and power consumption are reduced, but manufacturing variations in resonance frequency occur

Engineering Contradiction:

Improvechip areaVSAvoidresonance frequency consistency

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The single resonant structure is segmented into four identical tuning forks arranged in two orthogonal pairs. Each tuning fork is mechanically coupled to the others through a common anchor structure, creating a modular system where identical components can be manufactured with reduced individual variation impact on the overall resonance frequency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces asymmetric mechanical coupling through the common anchor structure that connects the four tuning forks. This asymmetric anchoring arrangement compensates for manufacturing variations by creating a balanced mechanical system where the coupling forces distribute stress evenly across all forks, stabilizing the overall resonance frequency despite individual fork variations.

Inventive Principle:

Principle #4Asymmetry

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 reduces chip space requirements and power consumption by enabling simultaneous sensing of yaw rate in two axes with a single resonant structure, improving signal-to-noise ratio and simplifying the manufacturing process.

Implementation Method 1

the Coriolis force may change the stress on micromechanical beam contained therein

Methodology Applied

Scientific EffectCoriolis force: Coriolis Force

Implementation Method 2

The change in stress may be measured, for example, using principles of piezoelectronics or piezioresistance

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 3

capacitive, piezoelectric, or piezoresistive elements for driving and sensing

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 4

capacitive, piezoelectric, or piezoresistive elements for driving and sensing

Methodology Applied

Scientific EffectPiezoresistive effect: Piezoresistive Effect

Data Source

PatentUS7401517B2Dual-axis yaw rate sensing unit having a tuning fork gyroscope arrangement

Publication Date: 2008.07.22 ROBERT BOSCH GMBH

AI summary

A dual-axis tuning fork gyroscope includes four open-ended tuning forks arranged coplanarly in two opposite pairs, a first pair of open-ended tuning forks being arranged opposite one another along a first axis, a second pair of open-ended tuning forks being arranged opposite one another along a second axis, the first axis and the second axis being perpendicular to one another. The four open-ended tuning forks are mechanically coupled together so that all four tuning forks vibrate in the same manner in terms of frequency and phase.