MEMS Inertial Sensor Direct Relative Movement Detection

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Solution Overview

Problem

Inertial sensors face performance degradation due to inaccuracies generated by complex processing operations required for detecting relative movements of seismic bodies, which are affected by parasitic movements and differing detector gains, particularly in applications like vehicle piloting and navigation.

Innovation Solution

A MEMS inertial sensor design featuring a frame with seismic bodies connected by elastic means, transducers with integral electrodes for direct measurement of relative movements, and a control unit for signal transmission through semiconductor layers with conduction paths, eliminating the need for external connections that could cause disturbances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If complex processing operations are used to detect relative movements of seismic bodies, then measurement capability is achieved, but measurement precision deteriorates due to processing inaccuracies

Engineering Contradiction:
Improvedetection accuracyVSAvoidprocessing operations
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the complex processing operations from the detection system. By using electrodes directly integrated with the seismic bodies to measure relative movements, the system removes the need for separate processing steps that introduced inaccuracies, achieving direct measurement of the physical quantity of interest

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces electrodes as an intermediary element that directly couples the seismic bodies to the measurement system. These electrodes serve as a mediator that translates mechanical movements into electrical signals without requiring complex processing, thereby improving measurement precision while reducing system complexity

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If detectors with different gains are used to detect seismic body movements, then detection coverage is improved, but measurement precision deteriorates due to parasitic movements

Engineering Contradiction:
Improvedetection coverageVSAvoidmeasurement accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent merges the detection functions into a unified system where electrodes directly attached to seismic bodies measure relative movements. This combination eliminates the need for multiple detectors with different gains, as the direct measurement approach inherently compensates for variations and eliminates parasitic movement components

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If external connection means are used to transmit measurement signals, then signal transmission is achieved, but reliability deteriorates due to disturbances in seismic body movements

Engineering Contradiction:
Improvesignal transmission stabilityVSAvoidexternal connection means
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the electrodes with the seismic bodies themselves, creating an integrated structure where the measurement elements are part of the measured object. This eliminates external connections that could disturb seismic body movements, thereby improving reliability without adding device complexity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The seismic bodies serve their dual function of both being the object of measurement and providing the electrical connection path through integrated electrodes. This self-service approach eliminates the need for separate external connection means, reducing disturbances and improving signal transmission stability

Inventive Principle:
Principle #25Self-service

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

Simplifies the detection of relative movements, reducing processing inaccuracies and enhancing sensor performance by directly measuring seismic body movements within the suspension plane, thereby improving attitude and speed detection capabilities.

Implementation Method 1

a control unit connected to the transducers by electrical conduction means

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

seismic bodies connected to said frame by elastic means of the sensor to be movable in a plane of suspension

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3071933B1Sensor including moving masses and means for detecting relative movements of the masses
Publication Date: 2020.07.01 SAFRAN ELECTRONICS & DEFENSE (FR)
  • EP3071933B1 patent drawingFigure 1~2
  • EP3071933B1 patent drawingFigure 3~4
  • EP3071933B1 patent drawingFigure 5

AI summary

The invention relates to a MEMS inertial sensor, including a frame to which at least a first seismic body and a second seismic body are connected by resilient means such as to be movable in a suspension plane, transducers to keep the seismic bodies vibrating and determine a movement of the seismic bodies in the suspension plane, and a control unit connected to the transducers by electrical conduction means. The transducers comprise at least one electrode rigidly connected to the first seismic body and one electrode rigidly connected to the second seismic body, the two electrodes being arranged such as to allow direct measurement of the relative movement of the seismic bodies relative to one another in the suspension plane.