Micromechanical Inertial Sensor Tilting Mass Anchor Design

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Solution Overview

Problem

Current yaw rate sensors face challenges in maintaining sensitivity while improving robustness against environmental influences such as shock and vibration, which can lead to adhesion issues and reduced sensitivity due to the external sensor structures' tendency to stick or become stuck.

Innovation Solution

A rotation rate sensor design with a drive and detection arrangement where the masses are arranged symmetrically around a center, with one mass at a greater distance from the center capable of tilting out of the plane under Coriolis force, connected to the substrate via external springs that support resetting this tilting, reducing the impact of environmental influences and maintaining sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If external sensor structures are positioned far from the anchor point to increase sensitivity, then measurement sensitivity is improved, but the tendency to adhesion to substrate surface increases

Engineering Contradiction:
ImprovesensitivityVSAvoidadhesion tendency
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent introduces a support structure (anchor element) as an intermediary between the mass and the substrate. This mediator provides mechanical support and prevents direct contact between the mass and substrate, eliminating adhesion while preserving the mass's position far from the anchor for high sensitivity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The support structure acts as a preventive measure against adhesion before it occurs. By providing continuous mechanical support through the anchor element, the system prevents the mass from adhering to the substrate under shock or vibration conditions.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Measurement precision

If external sensor structures are positioned far from the anchor point to increase sensitivity, then measurement sensitivity is improved, but shock resistance decreases

Engineering Contradiction:
ImprovesensitivityVSAvoidshock resistance
Core Design Contradiction:
Measurement precisionVSStrength

Solution Approach 1:

The anchor element serves as a mediator that provides mechanical support to the mass positioned far from the anchor. This intermediary structure absorbs and distributes shock forces, protecting the sensitive measurement components while maintaining the geometric configuration needed for high sensitivity.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If the mass is allowed to tilt freely under Coriolis force for accurate rotation measurement, then measurement accuracy is improved, but the tendency to adhesion to substrate increases

Engineering Contradiction:
Improverotation measurement accuracyVSAvoidadhesion tendency
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The support structure provides localized support at the anchor point while allowing the mass to tilt freely at its position. This local quality approach enables the mass to have the freedom of movement needed for accurate rotation measurement while the anchored location prevents adhesion to the substrate.

Inventive Principle:
Principle #3Local quality

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 design enhances the sensor's robustness against shock and vibration, reducing tilting by approximately 15-60% and minimizing adhesion issues, thereby maintaining sensitivity and improving linearity and noise reduction.

Implementation Method 1

The oscillating mass is set into a resonant movement, so that an oscillating velocity vector or an oscillating moment of inertia is impressed.

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 2

An acting Coriolis force leads to a corresponding orthogonal deflection movement of the oscillating mass (coupled) and can therefore be detected.

Methodology Applied
Scientific EffectCoriolis force: Coriolis Force

Implementation Method 3

characterized in that that of the two masses (3, 4) which is at a greater distance from the center is connected to the substrate via at least two connecting means (7), such that the resetting of the tilting from the xy plane is supported by the connecting means (7).

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2937666B1Micromechanical inertial sensor for measuring rotation rates
Publication Date: 2016.12.14 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP2937666B1 patent drawingFigure 1~2
  • EP2937666B1 patent drawingFigure 3A~4
  • EP2937666B1 patent drawingFigure 5~6C

AI summary

The invention relates to a rotation rate sensor for detecting a rotation Ω about which the sensor is rotated, wherein the sensor comprises a substrate and a drive and detection arrangement which is located substantially planarly in an xy-plane above the substrate surface, wherein the drive and detection arrangement comprises a drive mass (4) and a detection mass (3) which are arranged symmetrically around a center (Z) of the detection arrangement at different distances from this center and whose vibration modes can be partially transmitted to each other and are partially decoupled, wherein the primary motion of the drive mass is not or only partially detected by the detection mass or the drive mass cannot be tilted or deflected out of the xy-plane or only partially, wherein the rotation Ω is detected by thisthat a tilting of the detection mass out of the plane of the drive and detection arrangement is detected, wherein the mass (3, 4) that has a greater distance from the said center can tilt out of the said plane under the influence of Coriolis force, characterized in that the said tiltable mass (3, 4) is connected to the substrate via symmetrically arranged external anchors (7) such that the return of the said tilting is supported by the external anchors (7).