Acoustic Vector Sensor Using MEMS Accelerometer and Microphones
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing airborne acoustic vector sensors face challenges in accurately measuring acoustic intensity due to sensitivity losses and structural resonance issues, particularly at low frequencies, and require complex calibration processes to achieve reliable particle velocity and pressure measurements.
Innovation Solution
The development of an improved acoustic vector sensor (AIVS) using a triaxial MEMS accelerometer and MEMS microphones mounted within a lightweight solid body, supported by a suspension system, which applies calibrated amplitude and phase adjustments to minimize sensitivity losses and structural resonances, allowing for accurate measurement of airborne acoustic particle velocity and intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional airborne acoustic vector sensor is used, then particle velocity measurement is achieved, but sensitivity losses occur particularly at low frequencies
Solution Approach 1:
The patent changes the physical parameters of the sensor by using a triaxial accelerometer with significantly reduced mass (less than 1 gram, preferably less than 0.5 grams) compared to traditional sensors. This parameter change in mass enables the sensor to respond more effectively to low-frequency acoustic waves while maintaining measurement precision across the full frequency range.
Solution Approach 2:
The patent employs a composite structure combining a lightweight accelerometer with a suspension system consisting of flexible supports or springs. This composite design allows the sensor to maintain structural integrity while minimizing mass and reducing structural resonance, thereby improving low-frequency sensitivity without sacrificing measurement accuracy.
2Reliability
If the sensor mass is reduced to improve low-frequency sensitivity, then sensitivity at low frequencies improves, but structural resonance issues arise
Solution Approach 1:
The patent introduces a suspension system as an intermediary between the lightweight accelerometer and the external environment. This suspension system isolates the sensor mass from structural vibrations and resonance, allowing the sensor to achieve high low-frequency sensitivity without being adversely affected by structural resonance.
Solution Approach 2:
The patent uses flexible supports or spring elements as the suspension system, which act as flexible connections between the sensor mass and the mounting structure. These flexible elements are designed to have natural frequencies well below the acoustic measurement range, effectively filtering out structural resonance while permitting acoustic-induced motion of the lightweight sensor.
3Measurement precision
If complex calibration processes are applied, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent enables the sensor system to perform self-calibration by utilizing the known relationship between the accelerometer and microphone measurements. The processing system automatically determines calibration factors by analyzing the coupled measurements, eliminating the need for complex external calibration procedures while maintaining high measurement accuracy.
Solution Approach 2:
The patent implements a feedback mechanism where the processing system continuously analyzes the relationship between accelerometer-derived particle velocity and microphone-derived acoustic pressure to automatically adjust and refine calibration factors. This feedback-based calibration approach simplifies the overall process while ensuring accurate acoustic intensity estimation.
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
The AIVS achieves enhanced sensitivity and reduced structural resonance, enabling accurate measurement of acoustic intensity across a broader frequency range while reducing costs, making it suitable for applications like drone tracking in urban environments.
Implementation Method 1
a MEMS-based acoustic vector sensor for measuring airborne acoustic particle velocity and intensity using a triaxial MEMS accelerometer and one or more MEMS microphones
Implementation Method 2
one or more MEMS microphones mounted within the lightweight solid body
Implementation Method 3
The accelerometer is mounted within or upon a lightweight solid body with density close to that of air, which in turn is supported by a suspension system within a framework
Data Source
AI summary
An airborne acoustic vector sensor for simultaneously measuring triaxial particle acceleration in three dimensions and pressure includes a triaxial MEMS accelerometer sensitive to an Earth gravitational field. The airborne acoustic vector sensor includes one or multiple MEMS microphones sensitive to sound pressure and overlapping the accelerometer in frequency. The airborne acoustic vector sensor includes a solid body having a density approximating a density of air. The accelerometer is mounted in or upon the solid body. The airborne acoustic vector sensor includes a suspension system supporting the accelerometer and solid body within a framework.