Accelerometer Noise Measurement Using MEMS Emulator

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional methods for determining the noise level of accelerometers are hindered by environmental noise interference during fabrication, making it difficult to accurately measure noise levels without isolating the device from ambient vibrations.

Innovation Solution

The proposed solution involves using a MEMS emulator component to generate an emulated output based on an estimate of Brownian noise, allowing the accelerometer to produce an output without exposure to external environmental inputs, thereby isolating the noise sources and enabling accurate noise level determination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the accelerometer is exposed to environmental input during measurement, then the measurement process is simple and fast, but the noise level measurement is contaminated by environmental noise vibrations

Engineering Contradiction:

Improvemeasurement speedVSAvoidnoise level measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The measurement process is segmented into two distinct phases: a calibration phase where environmental noise is characterized, and a measurement phase where the accelerometer is tested. This segmentation allows the system to separate environmental noise effects from the accelerometer's intrinsic noise, enabling accurate noise level measurement without requiring complete isolation from environmental inputs.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A noise estimation component acts as an intermediary between the environmental noise and the measurement system. This component processes the relationship between environmental inputs and sensor output to estimate and subtract environmental noise contributions, thereby isolating the accelerometer's intrinsic noise level without requiring physical isolation from environmental vibrations.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the accelerometer is isolated from environmental input, then the noise level measurement is accurate, but the measurement process becomes complex and time-consuming

Engineering Contradiction:

Improvenoise level measurement accuracyVSAvoidmeasurement system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system uses the accelerometer itself to characterize environmental noise by measuring its response to environmental inputs during calibration. The same accelerometer then uses this self-characterized noise profile to compensate for environmental effects during measurement, eliminating the need for external noise characterization equipment or complex isolation mechanisms.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Physical isolation mechanisms are replaced with a signal processing approach. Instead of mechanically isolating the accelerometer from environmental vibrations, the system uses digital signal processing and noise estimation algorithms to subtract environmental noise effects, simplifying the physical measurement setup while maintaining accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If conventional measurement approaches are used, then the measurement process is simple, but environmental noise prevents accurate determination of accelerometer noise level

Engineering Contradiction:

Improvemeasurement simplicityVSAvoidnoise level measurement accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system implements feedback by continuously using the calibrated noise profile to correct subsequent measurements. The noise estimation component processes the relationship between environmental inputs and sensor output in real-time, providing feedback that compensates for environmental noise effects and maintains measurement accuracy throughout the measurement process.

Inventive Principle:

Principle #23Feedback

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 effectively separates and measures noise sources, including Brownian noise, allowing for precise determination of the noise level of accelerometers even in environments with significant environmental noise, enhancing the accuracy and efficiency of the measurement process.

Implementation Method 1

estimating a first noise generated by operation of the MEMS component

Methodology Applied

Scientific EffectBrownian motion: Brownian Motion

Data Source

PatentUS11255876B2Measuring a noise level of an accelerometer

Publication Date: 2022.02.22 INVENSENSE INC

AI summary

A method of measuring noise of an accelerometer can comprise exposing the accelerometer comprising a micro-electro-mechanical system (MEMS) component coupled to an application specific integrated circuit component (ASIC), to an external environmental input, with the MEMS component being configured to provide a first output to the ASIC based on the external environmental input. The method can further comprise estimating a first noise generated by operation of the MEMS component, and replacing the first output provided to the ASIC from the MEMS component, with a second output generated by a MEMS emulator component, with the second output comprising the first noise. Further, the method can include generating an output of the accelerometer based on the second output processed by the ASIC.