Vibrating Micro-Sensor Vacuum Loss Detection

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Solution Overview

Problem

Micro-sensors with vibrating resonators face challenges in maintaining accuracy due to vacuum deterioration, leading to signal-to-noise ratio degradation and loss of precision, with existing solutions lacking effective fault diagnosis and degradation prognosis, particularly in critical applications like avionics where reliability is paramount.

Innovation Solution

A continuity parameter is defined to monitor the frequency measurement of a vibrating element, allowing early detection and quantification of vacuum loss, integrated into the sensor's self-testing system using available signals and minimal additional code, enabling real-time monitoring of vacuum quality and measurement reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a vibrating resonator is used for precise measurement, then measurement precision is improved, but reliability deteriorates due to vacuum deterioration and undetected degradation

Engineering Contradiction:
Improvemeasurement precisionVSAvoidreliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent implements preliminary action by continuously monitoring the quality factor Q and continuity parameter before vacuum deterioration significantly impacts measurement precision. The system detects early signs of vacuum loss through Q-factor degradation and anticipates measurement reliability issues before they occur, allowing preventive action to be taken.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies feedback by using the measured quality factor Q and continuity parameter to provide real-time information about vacuum conditions and sensor health. This feedback loop enables the system to adjust or alert operators about deteriorating vacuum conditions that would otherwise go undetected until measurement precision is compromised.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If vacuum is maintained for high quality factor, then measurement precision is improved, but device complexity increases due to vacuum sealing requirements

Engineering Contradiction:
Improvequality factorVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces mechanical vacuum monitoring systems with electrical measurement techniques. Instead of using mechanical sensors or complex vacuum gauges, the system uses electrical measurements of the resonator's quality factor Q and continuity parameter to infer vacuum conditions, thereby reducing mechanical complexity while maintaining precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The resonator itself serves as the vacuum indicator through its quality factor Q. The system uses the resonator's inherent electrical characteristics to monitor vacuum conditions without requiring separate vacuum sensing mechanisms, allowing the measurement element to perform dual functions: sensing and vacuum monitoring.

Inventive Principle:
Principle #25Self-service

3Reliability

If additional monitoring systems are added for fault detection, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improvefault detection capabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements universality by designing the monitoring system to use the same electrical signals and processing circuits already present in the resonator measurement system. The quality factor Q measurement and continuity parameter calculation reuse existing signal paths, amplifiers, and digital processing resources, allowing fault detection without adding dedicated monitoring hardware.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the vacuum monitoring and fault detection functions with the primary measurement system. The continuity parameter Qc and quality factor Q measurements are integrated into the existing signal processing chain, combining multiple monitoring objectives into a unified measurement architecture that avoids redundant components.

Inventive Principle:
Principle #5Merging (Combining)

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 approach enables real-time detection and anticipation of sensor degradation, providing valuable information on measurement reliability without disrupting operational functionality, ensuring accurate data in critical applications like avionics.

Implementation Method 1

a particular resonance mode of the vibrating resonator is used, controlled by an excitation circuit comprising an automatic gain control loop. An external physical quantity applied to the vibrating resonator is thus converted into a variation of the resonance frequency

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 2

controlled by an excitation circuit comprising an automatic gain control loop. Circuit 22 and setpoint C are designed to cause the vibrating element (or vibrating elements) of the resonator to oscillate with a predetermined oscillation amplitude A0

Methodology Applied
Scientific EffectAutomatic gain control: Feedback

Data Source

PatentEP2864735B1Sensor with a vibrating member in a cavity, with integrated anomaly detection
Publication Date: 2016.08.24 THALES SA
  • EP2864735B1 patent drawingFigure 1~2b
  • EP2864735B1 patent drawingFigure 3~4
  • EP2864735B1 patent drawingFigure 5~6

AI summary

The invention concerns vibrating micro-systems, and in particular but not exclusively pressure, acceleration or angular speed micro-sensors with a resonator in a vacuum cavity. The resonator (10) having a vibrating member is placed in an oscillating circuit controlled by a servo loop, the oscillating circuit providing an oscillation signal y(t) at a resonance frequency Fp representing the measurement of a physical quantity. The resonance frequency is calculated by means of a pulse count during a time window. The sensor further comprises means for calculating a continuity parameter Pc representing the variations in the result of the resonance frequency calculation during successive time windows, and means for comparing parameter Pc to a threshold in order to deduce therefrom a piece of information on the deterioration in the accuracy of the sensor.