Sensor Device Acousto-Mechanical Coupling for Distributed Acoustic Sensing
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Solution Overview
Problem
Existing remote sensing technologies, particularly distributed acoustic sensing (DAS), face limitations in monitoring additional environmental parameters along linear assets like pipelines and telecommunication networks, as they primarily focus on acoustic and vibrational data, lacking flexibility and versatility in sensor deployment and data collection.
Innovation Solution
A sensor device comprising a sensor element, processor, and actuator that produces mechanical vibrations, allowing for indirect coupling to an elongate fibre optic cable, enabling flexible and modular deployment along the fibre for monitoring various environmental parameters, including ambient light, temperature, and digital data, using acousto-mechanical signals that can be detected by the DAS system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If distributed acoustic sensing (DAS) is used to monitor linear assets, then acoustic and vibrational data can be detected along the fibre, but the system lacks the ability to monitor additional environmental parameters such as temperature, light, and digital data
Solution Approach 1:
The patent makes the fibre optic cable serve multiple functions: it acts as both the transmission medium for DAS acoustic/vibrational sensing and as a communication channel for transmitting encoded environmental data from sensor devices. This multi-functionality allows temperature, light, and digital data monitoring alongside acoustic sensing without requiring separate infrastructure
Solution Approach 2:
The patent introduces sensor devices as intermediary components that couple to the fibre optic cable. These sensor devices contain sensors for environmental parameters and actuators that convert sensor outputs into acoustic signals modulated onto the fibre, enabling indirect monitoring of environmental parameters through the DAS system
2Ease of operation
If traditional point sensors are deployed along the fibre, then specific locations can be monitored, but the system lacks flexibility in sensor placement and deployment
Solution Approach 1:
The sensor devices are designed to be self-contained units that autonomously sense environmental parameters, process the data through an onboard processor, encode the information acoustically, and transmit it via the fibre optic cable. This self-service capability eliminates the need for complex external deployment infrastructure and allows flexible placement at any location along the fibre
Solution Approach 2:
The patent divides the monitoring system into discrete, independent sensor devices that can be deployed individually at various locations along the fibre optic cable. Each sensor device is a self-contained module with sensor element, processor, and actuator, allowing flexible segmentation of the monitoring coverage without requiring continuous sensor arrays
3Reliability
If fibre optic cables are modified with mirrors, reflectors, or gratings to enhance sensing, then sensing performance improves, but the fibre can no longer be used for standard DAS applications
Solution Approach 1:
The patent introduces sensor devices as intermediary components that couple to the fibre optic cable. These sensor devices contain sensors for environmental parameters and actuators that convert sensor outputs into acoustic signals modulated onto the fibre, enabling indirect monitoring of environmental parameters through the DAS system
Solution Approach 2:
The patent applies local modifications only at specific sensor device locations rather than throughout the entire fibre. The sensor devices couple locally to the fibre at discrete points, leaving the majority of the fibre length unmodified and suitable for standard DAS applications
4Ease of manufacture
If acoustic signals are transmitted through the fibre to convey sensor data, then existing fibre infrastructure can be utilized, but noise interference may affect signal detection
Solution Approach 1:
The patent replaces direct electrical or optical signal transmission through the fibre with acoustic signal transmission. The sensor devices generate acoustic vibrations that modulate the fibre optic cable, and these acoustic signals are detected by the DAS system. This mechanical/acoustic approach leverages the fibre's existing acoustic sensing capability while avoiding electromagnetic interference
Solution Approach 2:
The DAS system provides distributed sensing feedback along the fibre length, allowing the system to detect and distinguish between acoustic signals generated by sensor devices and ambient noise. The coherent detection and signal processing capabilities enable discrimination of the modulated acoustic signals from background interference
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 solution provides enhanced sensing capabilities along fibre optic cables, allowing for the monitoring of diverse environmental parameters with flexible sensor placement, improved noise resilience, and extended operational periods, even in challenging access conditions, using existing fibre infrastructure.
Implementation Method 1
an actuator adapted to produce mechanical vibration in response to the received drive signal
Implementation Method 2
In distributed acoustic sensing, Rayleigh backscattering is normally used. Due to random inhomogeneities in standard optic fibres, a small amount of light from a pulse injected into a fibre is reflected back from every location along the length of the fibre
Implementation Method 3
An alternative approach to DAS is based on heterodyne interferometry. In this approach light which has passed through a given section of fibre is interfered with light that has not
Data Source
AI summary
A plurality of sensors output information into a distributed acoustic sensing (DAS) system via acousto-mechanical signals. The sensors are coupled to the optic fibre at the centre of the DAS system indirectly, the acousto-mechanical signal being transmitted via an intermediary body, such as the ground or a conduit.