Composite Vibratory In-Plane Accelerometer Frequency Adaptation
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Solution Overview
Problem
Vibratory inertial sensors face challenges in maintaining sensitivity when the sense mass is driven at a frequency that is not its optimal sensing frequency, particularly in systems with a single drive mechanism for multiple sensors, where allowing the sense mass to respond to accelerations at a frequency other than its drive frequency is necessary to maintain sensitivity.
Innovation Solution
A composite mass system is implemented, where the sense mass is mechanically coupled to a drive mass with springs having different spring constants, allowing the sense mass to respond to inertial forces at a frequency different from its drive frequency, while the drive mass is driven at its own resonant frequency, using time-domain switching to generate outputs based on currents from the sense mass motion and determining time intervals to calculate inertial parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the sense mass is driven at a single drive frequency by a single drive mechanism, then the system can be simplified and multiple sensors can share the drive mechanism, but the sense mass cannot maintain optimal sensitivity when the drive frequency differs from its resonant frequency
Solution Approach 1:
The mass system is segmented into a drive mass and a sense mass that are mechanically coupled but have different resonant frequencies. The drive mass is driven at its resonant frequency while the sense mass responds at its own resonant frequency, allowing each mass to operate optimally at different frequencies simultaneously.
Solution Approach 2:
The drive mass serves multiple functions: it acts as both the driven element (responding to drive signals at its resonant frequency) and the driving element (transmitting forces to the sense mass). This multi-functionality allows a single drive mechanism to effectively drive the sense mass at its optimal frequency.
2Adaptability or versatility
If the sense mass is mechanically coupled to the drive mass with springs having different spring constants, then the sense mass can respond at a different frequency than the drive mass, but the system complexity increases
Solution Approach 1:
The spring constants of the coupling springs are specifically selected to create different resonant frequencies for the drive mass and sense mass. By changing the physical parameters (spring constants) of the coupling elements, the system achieves frequency differentiation without complex mechanical structures.
3Measurement precision
If time-domain switching is used to generate outputs based on sense mass motion, then inertial parameters can be accurately determined, but the signal processing complexity increases
Solution Approach 1:
The system replaces complex continuous analog signal processing with simpler time-domain switching and digital time interval measurement. Instead of processing continuous analog signals, the system uses switching elements to generate digital outputs based on time intervals, simplifying the signal processing architecture.
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 the sense mass to maintain sensitivity and accurately measure inertial parameters at frequencies other than its drive frequency, enhancing the system's ability to detect a range of accelerations without compromising sensitivity.
Implementation Method 1
the sense mass is configured to respond to an inertial force in a first direction at a second frequency, while the drive mass is configured to be driven in the first direction at a first frequency
Implementation Method 2
the drive mass can be mechanically coupled to the sense mass with coupling springs compliant in the first direction
Implementation Method 3
A first time-domain switch is configured to generate an output based on a first current generated in part by motion of the sense mass
Data Source
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AI summary
Systems and methods are described herein for detecting and measuring inertial parameters, such as acceleration. In particular, the systems and methods relate to vibratory inertial sensors implementing time-domain sensing techniques. Within a composite mass sensor system, a sense mass may oscillate at a frequency different from its actuation frequency, allowing flexibility when integrating the sensor into drive systems without sacrificing sensitivity.