Abstract

In this paper, we focus on the problem of locating a scuba diver in distress using a sensor network. Without GPS reception, submerged divers in distress will transmit SOS messages using underwater acoustic communication. The study goal is to enable the quick and reliable location of a diver in distress by his fellow scuba divers. To this purpose, we propose a distributed scheme that relies on the propagation delay information of these acoustic SOS messages in the scuba divers’ network to yield a range and bearing evaluation to the diver in distress by any neighboring diver. We formalize the task as a non-convex, multi-objective graph localization constraint optimization problem. The solution finds the best configuration of the nodes’ graph under constraints in the form of upper and lower bounds derived from the inter-connections between the graph nodes/divers. Considering the need to rapidly propagate the SOS information, we flood the network with the SOS packet, while also using rateless coding to leverage information from colliding packets, and to utilize time instances when collisions occur for propagation delay evaluation. Numerical results show a localization accuracy on the order of a few meters, which contributes to quickly locating the diver in distress. Similar results were demonstrated in a controlled experiment in a water tank, and by playback data from a sea experiment for five network topologies.

Highlights

  • In the last decade, ocean exploration has considerably increased, as has the involvement of human divers performing maintenance work and site surveys

  • We offer a second alternative, referred to as conditional graph localization (GL) (CGL), whose output is the solution of an optimization problem that takes into account some upper and lower bounds on D (i )

  • We suggested an efficient distributed GL algorithm for estimating the relative location of a diver in distress, to enable timely assistance provided by fellow divers

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Summary

A Graph Localization Approach for Underwater Sensor

A Graph Localization Approach for Underwater Sensor Network to Assist a Diver in Distress. Hatter Department of Marine Technologies, University of Haifa, Haifa 3498838, Israel. 14th Workshop on Positioning, Navigation and Communications (WPNC). This journal version includes a different formalization of the problem, consideration of packet collisions, and a demonstration of results from a sea experiment

Introduction
State-of-the-Art for Underwater Network Localization
System Model
Key Idea
Position of the SOS Source
Finding the Coordinate Representation of the Graph
Matching of Coordinates
SOS Propagation
Estimation of the Propagation Delay
SOS Decoding
ToA Estimation
Performance Evaluation
Numerical Simulations
Tests in Water Tank
Data from a Sea Experiment
Findings
Conclusions
Full Text
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