Fiber Optic Accelerometer With Folded Flap Transducer
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Solution Overview
Problem
Traditional accelerometers require preamplifiers and electronic telemetry, which are bulky and expensive, especially in remote applications, and existing fiber optic accelerometers face limitations due to large fiber lengths and limited bend diameters, making them unsuitable for compact designs.
Innovation Solution
An accelerometer with a transducer featuring a substantially linear configuration and flaps that translate acceleration into strain, using a fiber laser sensor to measure strain, which eliminates the need for preamplification and electronic telemetry, and incorporates a lever arm to enhance sensitivity and bandwidth.
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 which are bulky and expensive
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 interference to measure acceleration. The fiber optic sensor detects strain directly through optical path length changes, eliminating the need for electrical preamplification and electronic telemetry components.
Solution Approach 2:
The patent introduces a fiber optic sensor as an intermediary between the acceleration event and the measurement system. The fiber optic acts as a mediator that converts mechanical acceleration into optical signal changes through strain-induced path length variations, which can be detected without electronic preamplification.
2Measurement precision
If fiber optic accelerometers use large coils of tens of meters of optical fiber, then acceleration can be measured through light modulation, but the large fiber length and limited bend diameter limit the accelerometer size
Solution Approach 1:
The patent segments the fiber optic path into multiple sections arranged in a folded configuration within a compact housing. Instead of using a single long coil of fiber, the fiber is divided into segments that are strategically positioned to achieve the required optical path length while maintaining a small overall device volume.
Solution Approach 2:
The patent transitions from a one-dimensional linear fiber arrangement to a three-dimensional folded configuration. The fiber optic is routed through multiple dimensions within the housing, creating a compact structure that achieves long optical path length without requiring large device volume.
3Ease of manufacture
If fiber optic sensor systems are used to remove preamplification requirements, then system expense is reduced, but very low sensitivity accelerometers based on optical waveguide misalignment require large sizes
Solution Approach 1:
The patent employs a folded fiber optic configuration that utilizes three-dimensional spatial arrangement to achieve compact size. The fiber is routed through multiple dimensions within the housing, allowing long optical paths to be contained in a small volume, thus maintaining sensitivity while reducing size.
Solution Approach 2:
The patent nests the fiber optic path within a compact housing structure, where the fiber is folded back on itself multiple times within the available space. This nesting approach allows the fiber to occupy minimal volume while still achieving the required optical path length for sensitive acceleration measurement.
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 provides a compact, sensitive, and cost-effective accelerometer that effectively measures acceleration by converting it into strain without the need for preamplifiers, offering improved cross-axis and longitudinal isolation and increased sensitivity through the use of a fiber laser sensor and lever arm design.
Implementation Method 1
A piece of fiber optic is provided that has a Bragg grating written in the fiber optic at either end of a sensing region. The sensing region is mounted to an object being measured, and elongation of the sensor can be measured by providing light pulses at a known interval in the fiber optic and collecting the reflected pulses.
Implementation Method 2
elongation of the sensor can be measured by providing light pulses at a known interval in the fiber optic and collecting the reflected pulses
Implementation Method 3
The flaps translate acceleration in a predefined direction to strain in the strain sensor
Implementation Method 4
Acceleration is sensed by measuring the electromotive force induced in the induction coil by movement of the magnetic mass
Implementation Method 5
Piezoceramic transducers use a piezoelectric effect to produce a low voltage output in response to force
Data Source
AI summary
An accelerometer is provided including a strain sensor with a substantially linear configuration. The strain sensor is mounted on a transducer such that the strain sensor extends laterally across the transducer. The transducer has a base and a plurality of flaps joined at a first end to the base and supporting the strain sensor at a second end. The flaps translate acceleration in a predefined direction to strain in the strain sensor. Further embodiments have flaps defining an interrupted surface with greater height at the center and flaps that have features for enhancing the strain caused by acceleration.