Fiber Optic Accelerometer Transducer with Flap Strain Amplification
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Solution Overview
Problem
Traditional accelerometers require preamplifiers and electronic telemetry, which are bulky and costly, especially in remote applications, and existing fiber optic accelerometers face limitations due to large optical fiber lengths and limited bend diameters, making them unsuitable for compact designs.
Innovation Solution
A transducer with a base and outer flaps that translates acceleration into strain using a fiber optic sensor, where the flaps' geometry and configuration enhance strain sensitivity and minimize cross-axis and longitudinal acceleration responses, allowing for a compact and sensitive accelerometer design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional electrical accelerometers use a magnetic mass supported by a spring with an induction coil, then acceleration can be sensed by measuring electromotive force, but the system requires preamplifiers and electronic telemetry that are bulky and costly
Solution Approach 1:
The patent replaces the traditional electrical sensing system (magnetic mass, induction coil, preamplifier) with a fiber optic sensing system that uses optical waves instead of electrical signals. The fiber optic sensor detects acceleration through optical path length changes, eliminating the need for electronic preamplifiers and reducing system complexity.
Solution Approach 2:
The patent introduces a fiber optic cable as an intermediary element that couples the reaction mass to the sensing system. This optical intermediary transmits acceleration information as optical signals, replacing the direct electrical measurement approach and enabling remote sensing without bulky electronics at the sensor location.
2Measurement precision
If fiber optic accelerometers use large coils of tens of meters of optical fiber, then acceleration can be measured, but the large amount of fiber and limited bend diameter limit the design to fairly large sizes
Solution Approach 1:
The patent segments the fiber optic path into distinct functional sections: a sensing region where the fiber is coupled to the reaction mass, and a transmission region where the fiber connects to the light source and detector. This segmentation allows the sensing region to be compact while the transmission fiber can be routed efficiently, reducing overall device size.
Solution Approach 2:
The patent arranges the fiber optic components in a three-dimensional configuration where the fiber is coupled to the reaction mass in a compact volume. By utilizing spatial arrangement and dimensional optimization, the design achieves compact size while maintaining the necessary optical path length for sensitive acceleration measurement.
3Measurement precision
If a fiber optic segment is positioned between a base and a ridged reaction mass to pinch the fiber, then acceleration can be measured by light modulation, but the design requires precise positioning and alignment
Solution Approach 1:
The patent designs the fiber optic coupling mechanism to serve multiple functions: it provides mechanical coupling between the reaction mass and base, enables optical signal transmission, and facilitates acceleration sensing. This multi-functionality reduces the need for separate alignment features and simplifies manufacturing.
Solution Approach 2:
The patent uses a flexible fiber optic cable that can accommodate slight misalignments and deformations during assembly and operation. The flexibility of the fiber allows for easier positioning and reduces the stringent alignment requirements compared to rigid optical components.
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 solution enables a compact, sensitive, and cost-effective accelerometer that effectively measures acceleration without the need for preamplifiers, offering improved sensitivity and reduced size constraints compared to traditional and existing fiber optic systems.
Implementation Method 1
elongation of the sensor can be measured by providing light pulses at a known interval in the fiber optic and collecting the reflected pulses. Elongation of the fiber optic sensor region causes a measurable delay in the pulses
Implementation Method 2
The outer flaps are capable of translating acceleration in the predefined direction to strain in the strain sensor
Data Source
AI summary
An accelerometer has a substantially linear strain sensor with a transducer joined to the strain sensor. The transducer has a base that provides rigidity perpendicular to a preferred measurement direction. A plurality of outer flaps are joined to the base supporting the strain sensor. The outer flaps are capable of translating acceleration in the predefined direction to strain in the strain sensor. Two centermost flaps are positioned on either side of the center line of the transducer. Struts are joined between a lower portion of one the centermost flap and an uppermost portion of the nearest outer flap. The struts enhance strain by linking outer flap motion to the centermost flaps. Bridges are joined between each two adjacent outer flaps supporting the strain sensor.