Self-compensating Resonantly Vibrating Accelerometer with Neural Network Processing
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Solution Overview
Problem
Conventional accelerometers face challenges in accurately measuring acceleration while being immune to dynamic environmental changes such as temperature, pressure, and cross-axis accelerations, due to cross-coupling spectral features that were previously obscured by noise but now revealed by improved noise floors.
Innovation Solution
The design incorporates identical vibrating sensors driven at multiple resonant mode frequencies, with a proof mass applying loads that cause difference frequencies to vary monotonically with acceleration, and a processing module that compensates for environmental variations using statistical or machine learning algorithms, including neural networks, to generate robust acceleration measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional accelerometers use single-frequency operation, then device complexity is low, but measurement precision deteriorates due to cross-coupling spectral features
Solution Approach 1:
The patent segments the vibrational response into multiple distinct resonant modes (e.g., fundamental mode at frequency f1 and higher-order modes at frequencies f2, f3, etc.). Each mode is excited and detected separately, allowing the system to resolve cross-coupling spectral features that would otherwise overlap and degrade measurement precision in single-frequency operation.
Solution Approach 2:
The system employs periodic excitation at multiple discrete resonant frequencies, alternating between different mode excitations. This periodic multi-frequency action allows the accelerometer to systematically probe different vibrational modes and extract acceleration information while avoiding the cross-coupling interference that plagues single-frequency operation.
2Adaptability or versatility
If accelerometers operate in dynamically changing environments, then adaptability is improved, but measurement precision deteriorates due to temperature and pressure variations
Solution Approach 1:
The patent exploits changes in resonant frequency parameters as environmental indicators. By monitoring how the resonant frequencies f1, f2, f3 shift in response to temperature and pressure variations, the system can compensate for environmental effects and maintain measurement precision across dynamically changing conditions.
Solution Approach 2:
The system implements feedback by continuously monitoring the resonant frequencies of multiple vibrational modes and using this information to adjust and compensate for environmental variations. The measured frequency shifts feed back into the processing algorithm to correct acceleration measurements, maintaining precision despite environmental changes.
3Measurement precision
If multiple vibrational modes are used, then measurement precision is improved through cross-coupling suppression, but device complexity increases
Solution Approach 1:
The patent employs a universal excitation and detection approach where the same basic circuitry and sensor structure handle multiple vibrational modes. The excitation circuit can generate multiple frequencies, and the detection circuit can resolve multiple resonant responses, allowing a single multi-functional system to achieve cross-coupling suppression without proportionally increasing complexity.
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 results in acceleration measurements with reduced bias and scale factor variations, achieving immunity to dynamic environmental changes and improving measurement accuracy.
Implementation Method 1
Each vibrating sensor exhibits a corresponding set of fundamental and higher-order vibrational modes, each characterized by a corresponding fundamental or higher-order resonant mode frequency
Implementation Method 2
The first excitation-and-detection circuit drives the first vibrating sensor at a first selected resonant mode frequency f1
Implementation Method 3
acceleration of the apparatus in a first direction along a sensing axis causes the proof mass to apply tensile and compressive loads to the first and second vibrating sensors, respectively
Data Source
AI summary
An inventive accelerometer includes a proof mass and a pair of vibrating sensors. Excitation-and-detection circuits drive vibrational modes of one sensor at resonant frequencies f1, F1, and F′1, and drive those same vibrational modes of the other sensor at resonant frequencies f2, F2, and F′2. Compressive or tensile loads oppositely applied by the proof mass to the vibrating sensors cause difference frequencies Δf=f1−f2, ΔF=F1−F2, and ΔF′=F′1−F′2 to vary monotonically with acceleration of the apparatus along a sensing axis. A measurement of acceleration can be generated based at least in part on a linear or nonlinear function of one or more or all of f1, f2, F1, F2, F′1, or F′2, and can be generated using a trained neural network.