Engineering › Ocean Engineering

Underwater Vehicles and Communication Systems

Works Count: 52158

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Description

This cluster of papers focuses on the research challenges, advancements, and applications in underwater acoustic sensor networks and communication. It covers topics such as propagation models, AUV navigation, localization techniques, energy-efficient routing, underwater gliders, autonomous underwater vehicles, and wireless sensor networks for oceanographic research.

Keywords

Underwater Acoustic Sensor Networks; Acoustic Communications; Underwater Gliders; Autonomous Underwater Vehicles; Localization Techniques; Wireless Sensor Networks; Channel Models; Energy-Efficient Routing; Underwater Robotics; Oceanographic Research

Verification of a six-degree of freedom simulation model for the REMUS autonomous underwater vehicle

2001-01-01

Timothy Prestero

Improving the performance of modular, low-cost autonomous underwater vehicles (AUVs) in such applications as long-range oceanographic survey, autonomous docking, and shallow-water mine countermeasures requires improving the vehicles' maneuvering precision and … Improving the performance of modular, low-cost autonomous underwater vehicles (AUVs) in such applications as long-range oceanographic survey, autonomous docking, and shallow-water mine countermeasures requires improving the vehicles' maneuvering precision and battery life. These goals can be achieved through the improvement of the vehicle control system. A vehicle dynamics model based on a combination of theory and empirical data would provide an efficient platform for vehicle control system development, and an alternative to the typical trial-and-error method of vehicle control system field tuning. As there exists no standard procedure for vehicle modeling in industry, the simulation of each vehicle system represents a new challenge. Developed by von Alt and associates at the Woods Hole Oceanographic Institute, the REMUS AUV is a small, low-cost platform serving in a range of oceanographic applications. This thesis describes the development and verification of a six degree of freedom, non-linear simulation model for the REMUS vehicle, the first such model for this platform. In this model, the external forces and moments resulting from hydrostatics, hydrodynamic lift and drag, added mass, and the control inputs of the vehicle propeller and fins are all defined in terms of vehicle coefficients. This thesis describes the derivation of these coefficients in detail. The equations determining the coefficients, as well as those describing the vehicle rigid-body dynamics, are left in non-linear form. to better simulate the inherently non-linear behavior of the vehicle. Simulation of the vehicle motion is achieved through numeric integration of the equations of motion. The simulator output is then checked against vehicle dynamics data collected in experiments performed at sea. The simulator is shown to accurately model the motion of the vehicle.

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VBF: Vector-Based Forwarding Protocol for Underwater Sensor Networks

2006-01-01

Peng Xie , Jun‐Hong Cui , Li Lao

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Underwater acoustic system analysis

1984-04-01

William S. Burdic

The challenges of building scalable mobile underwater wireless sensor networks for aquatic applications

2006-05-01

Jun‐Hong Cui , Jiejun Kong , Mário Gerla +1 more

The large-scale mobile underwater wireless sensor network (UWSN) is a novel networking paradigm to explore aqueous environments. However, the characteristics of mobile UWSNs, such as low communication bandwidth, large propagation … The large-scale mobile underwater wireless sensor network (UWSN) is a novel networking paradigm to explore aqueous environments. However, the characteristics of mobile UWSNs, such as low communication bandwidth, large propagation delay, floating node mobility, and high error probability, are significantly different from ground-based wireless sensor networks. The novel networking paradigm poses interdisciplinary challenges that will require new technological solutions. In particular, in this article we adopt a top-down approach to explore the research challenges in mobile UWSN design. Along the layered protocol stack, we proceed roughly from the top application layer to the bottom physical layer. At each layer, a set of new design intricacies is studied. The conclusion is that building scalable mobile UWSNs is a challenge that must be answered by interdisciplinary efforts of acoustic communications, signal processing, and mobile acoustic network protocol design.

AUV Navigation and Localization: A Review

2014-01-01

Liam Paull , Sajad Saeedi , Mae Seto +1 more

Autonomous underwater vehicle (AUV) navigation and localization in underwater environments is particularly challenging due to the rapid attenuation of Global Positioning System (GPS) and radio-frequency signals. Underwater communications are low … Autonomous underwater vehicle (AUV) navigation and localization in underwater environments is particularly challenging due to the rapid attenuation of Global Positioning System (GPS) and radio-frequency signals. Underwater communications are low bandwidth and unreliable, and there is no access to a global positioning system. Past approaches to solve the AUV localization problem have employed expensive inertial sensors, used installed beacons in the region of interest, or required periodic surfacing of the AUV. While these methods are useful, their performance is fundamentally limited. Advances in underwater communications and the application of simultaneous localization and mapping (SLAM) technology to the underwater realm have yielded new possibilities in the field. This paper presents a review of the state of the art of AUV navigation and localization, as well as a description of some of the more commonly used methods. In addition, we highlight areas of future research potential.

Multi-AUV Control and Adaptive Sampling in Monterey Bay

2006-10-01

E. Fiorelli , Naomi Ehrich Leonard , Pradeep Bhatta +3 more

Operations with multiple autonomous underwater vehicles (AUVs) have a variety of underwater applications. For example, a coordinated group of vehicles with environmental sensors can perform adaptive ocean sampling at the … Operations with multiple autonomous underwater vehicles (AUVs) have a variety of underwater applications. For example, a coordinated group of vehicles with environmental sensors can perform adaptive ocean sampling at the appropriate spatial and temporal scales. We describe a methodology for cooperative control of multiple vehicles based on virtual bodies and artificial potentials (VBAP). This methodology allows for adaptable formation control and can be used for missions such as gradient climbing and feature tracking in an uncertain environment. We discuss our implementation on a fleet of autonomous underwater gliders and present results from sea trials in Monterey Bay in August, 2003. These at-sea demonstrations were performed as part of the Autonomous Ocean Sampling Network (AOSN) II project

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A new optimization method: Dolphin echolocation

2013-04-23

A. Kaveh , Neda Farhoudi

Statistical Characterization and Computationally Efficient Modeling of a Class of Underwater Acoustic Communication Channels

2013-10-01

Parastoo Qarabaqi , Milica Stojanovic

Underwater acoustic channel models provide a tool for predicting the performance of communication systems before deployment, and are thus essential for system design. In this paper, we offer a statistical … Underwater acoustic channel models provide a tool for predicting the performance of communication systems before deployment, and are thus essential for system design. In this paper, we offer a statistical channel model which incorporates physical laws of acoustic propagation (frequency-dependent attenuation, bottom/surface reflections), as well as the effects of inevitable random local displacements. Specifically, we focus on random displacements on two scales: those that involve distances on the order of a few wavelengths, to which we refer as small-scale effects, and those that involve many wavelengths, to which we refer as large-scale effects. Small-scale effects include scattering and motion-induced Doppler shifting, and are responsible for fast variations of the instantaneous channel response, while large-scale effects describe the location uncertainty and changing environmental conditions, and affect the locally averaged received power. We model each propagation path by a large-scale gain and micromultipath components that cumulatively result in a complex Gaussian distortion. Time- and frequency-correlation properties of the path coefficients are assessed analytically, leading to a computationally efficient model for numerical channel simulation. Random motion of the surface and transmitter/receiver displacements introduce additional variation whose temporal correlation is described by Bessel-type functions. The total energy, or the gain contained in the channel, averaged over small scale, is modeled as log-normally distributed. The models are validated using real data obtained from four experiments. Specifically, experimental data are used to assess the distribution and the autocorrelation functions of the large-scale transmission loss and the short-term path gains. While the former indicates a log-normal distribution with an exponentially decaying autocorrelation, the latter indicates a conditional Ricean distribution with Bessel-type autocorrelation.

Recent advances in high-speed underwater acoustic communications

1996-04-01

Milica Stojanovic

In recent years, underwater acoustic (UWA) communications have received much attention as their applications have begun to shift from military toward commercial. Digital communications through UWA channels differ substantially from … In recent years, underwater acoustic (UWA) communications have received much attention as their applications have begun to shift from military toward commercial. Digital communications through UWA channels differ substantially from those in other media, such as radio channels, due to severe signal degradations caused by multipath propagation and high temporal and spatial variability of the channel conditions. The design of underwater acoustic communication systems has until recently relied on the use of noncoherent modulation techniques. However, to achieve high data rates on the severely band-limited UWA channels, bandwidth-efficient modulation techniques must be considered, together with array processing for exploitation of spatial multipath diversity. The new generation of underwater communication systems, employing phase-coherent modulation techniques, has a potential of achieving at least an order of magnitude increase in data throughput. The emerging communication scenario in which the modern underwater acoustic systems mill operate is that of an underwater network consisting of stationary and mobile nodes. Current research focuses on the development of efficient signal processing algorithms, multiuser communications in the presence of interference, and design of efficient modulation and coding schemes. This paper presents a review of recent results and research problems in high-speed underwater acoustic communications, focusing on the bandwidth-efficient phase-coherent methods. Experimental results are included to illustrate the state-of-the-art coherent detection of digital signals transmitted at 30 and 40 kb/s through a rapidly varying one-mile shallow water channel.

Autonomous Oceanographic Sampling Networks

1993-01-01

Thomas Curtin , James G. Bellingham , Josko Catipovic +1 more

Spatially adaptivesampling is necessary to resolve evolving gradients with sparsely distributed sensors. Spatially adaptivesampling is necessary to resolve evolving gradients with sparsely distributed sensors.

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Collective Motion, Sensor Networks, and Ocean Sampling

2007-01-01

Naomi Ehrich Leonard , Derek A. Paley , François Lekien +3 more

This paper addresses the design of mobile sensor networks for optimal data collection. The development is strongly motivated by the application to adaptive ocean sampling for an autonomous ocean observing … This paper addresses the design of mobile sensor networks for optimal data collection. The development is strongly motivated by the application to adaptive ocean sampling for an autonomous ocean observing and prediction system. A performance metric, used to derive optimal paths for the network of mobile sensors, defines the optimal data set as one which minimizes error in a model estimate of the sampled field. Feedback control laws are presented that stably coordinate sensors on structured tracks that have been optimized over a minimal set of parameters. Optimal, closed-loop solutions are computed in a number of low-dimensional cases to illustrate the methodology. Robustness of the performance to the influence of a steady flow field on relatively slow-moving mobile sensors is also explored

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Underwater Gliders for Ocean Research

2004-06-01

Daniel L. Rudnick , Russ E. Davis , Charles C. Eriksen +2 more

Underwater gliders are autonomous vehicles that profile vertically by controlling buoyancy and move horizontally on wings. Gliders are reviewed, from their conception by Henry Stommel as an extension of autonomous … Underwater gliders are autonomous vehicles that profile vertically by controlling buoyancy and move horizontally on wings. Gliders are reviewed, from their conception by Henry Stommel as an extension of autonomous profiling floats, through their development in three models, and including their first deployments singly and in numbers. The basics of glider function are discussed as implemented by University of Washington in Seaglider, Scripps Institution of Oceanography in Spray, and Webb Research in Slocum. Gliders sample in the archetypical modes of sections and of "virtual moorings." Preliminary results are presented from a recent demonstration project that used a network of gliders off Monterey. A wide range of sensors has already been deployed on gliders, with many under current development, and an even wider range of future possibilities. Glider networks appear to be one of the best approaches to achieving subsurface spatial resolution necessary for ocean research.

A survey of dynamic positioning control systems

2011-04-01

Asgeir J. Sørensen

Slotted FAMA: a MAC protocol for underwater acoustic networks

2006-05-01

Marcal Molins , Milica Stojanovic

Long propagation delays and low bit rates of underwater acoustic networks make these systems fundamentally different from the packet radio networks. As a consequence, many of the network protocols designed … Long propagation delays and low bit rates of underwater acoustic networks make these systems fundamentally different from the packet radio networks. As a consequence, many of the network protocols designed for radio channels are either not applicable, or have extremely low efficiency over underwater acoustic channels. These facts necessitate a dedicated design of protocols for an underwater acoustic network. A medium access control (MAC) protocol suitable for an underwater acoustic network is proposed and analyzed. The protocol is based on a channel access discipline called floor acquisition multiple access (FAMA) which combines both carrier sensing (CS) and a dialogue between the source and receiver prior to data transmission. During the initial dialogue, control packets are exchanged between the source node and the intended destination node to avoid multiple transmissions at the same time. Special attention is paid to the networks that are not fully connected, in which nodes can be hidden from each other. The new protocol uses time slotting and is thus called slotted FAMA. Time slotting eliminates the need for excessively long control packets, thus providing savings in energy. Protocol performance in throughput and delay is assessed through simulation of a mobile ad hoc underwater network, showing the existence of optimal power level to be used for a given user density.

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Multicarrier Communication Over Underwater Acoustic Channels With Nonuniform Doppler Shifts

2008-04-01

Baosheng Li , Shengli Zhou , Milica Stojanovic +2 more

Underwater acoustic (UWA) channels are wideband in nature due to the small ratio of the carrier frequency to the signal bandwidth, which introduces frequency-dependent Doppler shifts. In this paper, we … Underwater acoustic (UWA) channels are wideband in nature due to the small ratio of the carrier frequency to the signal bandwidth, which introduces frequency-dependent Doppler shifts. In this paper, we treat the channel as having a common Doppler scaling factor on all propagation paths, and propose a two-step approach to mitigating the Doppler effect: 1) nonuniform Doppler compensation via resampling that converts a "wideband" problem into a "narrowband" problem and 2) high-resolution uniform compensation of the residual Doppler. We focus on zero-padded orthogonal frequency-division multiplexing (OFDM) to minimize the transmission power. Null subcarriers are used to facilitate Doppler compensation, and pilot subcarriers are used for channel estimation. The receiver is based on block-by-block processing, and does not rely on channel dependence across OFDM blocks; thus, it is suitable for fast-varying UWA channels. The data from two shallow-water experiments near Woods Hole, MA, are used to demonstrate the receiver performance. Excellent performance results are obtained even when the transmitter and the receiver are moving at a relative speed of up to 10 kn, at which the Doppler shifts are greater than the OFDM subcarrier spacing. These results suggest that OFDM is a viable option for high-rate communications over wideband UWA channels with nonuniform Doppler shifts.

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Challenges for efficient communication in underwater acoustic sensor networks

2004-07-01

Ian F. Akyildiz , Dario Pompili , Tommaso Melodia

Ocean bottom sensor nodes can be used for oceanographic data collection, pollution monitoring, offshore exploration and tactical surveillance applications. Moreover, Unmanned or Autonomous Underwater Vehicles (UUVs, AUVs), equipped with sensors, … Ocean bottom sensor nodes can be used for oceanographic data collection, pollution monitoring, offshore exploration and tactical surveillance applications. Moreover, Unmanned or Autonomous Underwater Vehicles (UUVs, AUVs), equipped with sensors, will find application in exploration of natural undersea resources and gathering of scientific data in collaborative monitoring missions. Underwater acoustic networking is the enabling technology for these applications. Underwater Networks consist of a variable number of sensors and vehicles that are deployed to perform collaborative monitoring tasks over a given area.In this paper, several fundamental key aspects of underwater acoustic communications are investigated. Different architectures for two-dimensional and three-dimensional underwater sensor networks are discussed, and the underwater channel is characterized. The main challenges for the development of efficient networking solutions posed by the underwater environment are detailed at all layers of the protocol stack. Furthermore, open research issues are discussed and possible solution approaches are outlined.

SLOCUM: an underwater glider propelled by environmental energy

2001-01-01

Doug Webb , Philippe Simonetti , C. Jones

SLOCUM is a small gliding AUV of 40 000-km operational range which harvests its propulsive energy from the heat flow between the vehicle engine and the thermal gradient of the … SLOCUM is a small gliding AUV of 40 000-km operational range which harvests its propulsive energy from the heat flow between the vehicle engine and the thermal gradient of the temperate and tropical ocean. The design of both the glider and the thermal engine are discussed including the design genesis and approach, field trial results, concept strength, and limitations and potential use.

The autonomous underwater glider "Spray"

2001-01-01

J. Sherman , Russ E. Davis , W. Brechner Owens +1 more

A small (50-kg, 2-m long) underwater vehicle with operating speeds of 20-30 cm/s and ranges up to 6000 km has been developed and field tested. The vehicle is essentially an … A small (50-kg, 2-m long) underwater vehicle with operating speeds of 20-30 cm/s and ranges up to 6000 km has been developed and field tested. The vehicle is essentially an autonomous profiling float that uses a buoyancy engine to cycle vertically and wings to glide horizontally while moving up and down. Operational control and data relay is provided by GPS navigation and two-way communication through ORBCOMM low-Earth-orbit satellites. Missions are envisioned with profile measurements repeated at a station or spaced along a transect. The initial instrument complement of temperature, conductivity, and pressure sensors was used to observe internal waves and tides in the Monterey underwater canyon.

A survey of practical issues in underwater networks

2006-01-01

Jim Partan , Jim Kurose , Brian Neil Levine

Article Share on A survey of practical issues in underwater networks Authors: Jim Partan University of Massachusetts, Amherst, MA & Woods Hole Oceanographic Institution, Woods Hole, MA University of Massachusetts, … Article Share on A survey of practical issues in underwater networks Authors: Jim Partan University of Massachusetts, Amherst, MA & Woods Hole Oceanographic Institution, Woods Hole, MA University of Massachusetts, Amherst, MA & Woods Hole Oceanographic Institution, Woods Hole, MAView Profile , Jim Kurose University of Massachusetts, Amherst, MA University of Massachusetts, Amherst, MAView Profile , Brian Neil Levine University of Massachusetts, Amherst, MA University of Massachusetts, Amherst, MAView Profile Authors Info & Claims WUWNet '06: Proceedings of the 1st ACM international workshop on Underwater networksSeptember 2006 Pages 17–24https://doi.org/10.1145/1161039.1161045Online:25 September 2006Publication History 298citation1,265DownloadsMetricsTotal Citations298Total Downloads1,265Last 12 Months11Last 6 weeks2 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access

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The state of the art in underwater acoustic telemetry

2000-01-01

Daniel Kilfoyle , A. B. Baggeroer

Progress in underwater acoustic telemetry since 1982 is reviewed within a framework of six current research areas: (1) underwater channel physics, channel simulations, and measurements; (2) receiver structures; (3) diversity … Progress in underwater acoustic telemetry since 1982 is reviewed within a framework of six current research areas: (1) underwater channel physics, channel simulations, and measurements; (2) receiver structures; (3) diversity exploitation; (4) error control coding; (5) networked systems; and (6) alternative modulation strategies. Advances in each of these areas as well as perspectives on the future challenges facing them are presented. A primary thesis of this paper is that increased integration of high-fidelity channel models into ongoing underwater telemetry research is needed if the performance envelope (defined in terms of range, rate, and channel complexity) of underwater modems is to expand.

On the relationship between capacity and distance in an underwater acoustic communication channel

2006-01-01

Milica Stojanovic

Path loss of an underwater acoustic communication channel depends not only on the transmission distance, but also on the signal frequency. As a result, the useful bandwidth depends on the … Path loss of an underwater acoustic communication channel depends not only on the transmission distance, but also on the signal frequency. As a result, the useful bandwidth depends on the transmission distance, a feature that distinguishes an underwater acoustic system from a terrestrial radio one. This fact influences the design of an acoustic network: a greater information throughput is available if messages are relayed over multiple short hops instead of being transmitted directly over one long hop.We asses the bandwidth dependency on the distance using an analytical method that takes into account physical models of acoustic propagation loss and ambient noise. A simple, single-path time-invariant model is considered as a first step. To assess the fundamental bandwidth limitation, we take an information-theoretic approach and define the bandwidth corresponding to optimal signal energy allocation -- one that maximizes the channel capacity subject to the constraint that the transmission power is finite. Numerical evaluation quantifies the bandwidth and the channel capacity, as well as the transmission power needed to achieve a pre-specified SNR threshold, as functions of distance. These results lead to closed-form approximations, which may become useful tools in the design and analysis of acoustic networks.

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Phase-coherent digital communications for underwater acoustic channels

1994-01-01

Milica Stojanovic , Josko Catipovic , J.G. Proakis

High-speed phase coherent communications in the ocean channel are made difficult by the combined effects of large Doppler fluctuations and extended, time-varying multipath. In order to account for these effects, … High-speed phase coherent communications in the ocean channel are made difficult by the combined effects of large Doppler fluctuations and extended, time-varying multipath. In order to account for these effects, we consider a receiver which performs optimal phase synchronization and channel equalization jointly. Since the intersymbol interference in some underwater acoustic channels spans several tens of symbol intervals, making the optimal maximum-likelihood receiver unacceptably complex, we use a suboptimal, but low complexity, decision feedback equalizer. The mean squared error multiparameter optimization results in an adaptive algorithm which is a combination of recursive least squares and second-order digital phase and delay-locked loops. The use of a fractionally spaced equalizer eliminates the need for explicit symbol delay tracking. The proposed algorithm is applied to experimental data from three types of underwater acoustic channels: long-range deep water, long-range shallow water, and short-range shallow water channels. The modulation techniques used are 4- and 8-PSK. The results indicate the feasibility of achieving power-efficient communications in these channels and demonstrate the ability to coherently combine multiple arrivals, thus exploiting the diversity inherent in multipath propagation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>

High bandwidth underwater optical communication

2008-01-09

Frank Hanson , Stojan Radic

We report error-free underwater optical transmission measurements at 1 Gbit/s (10(9) bits/s) over a 2 m path in a laboratory water pipe with up to 36 dB of extinction. The … We report error-free underwater optical transmission measurements at 1 Gbit/s (10(9) bits/s) over a 2 m path in a laboratory water pipe with up to 36 dB of extinction. The source at 532 nm was derived from a 1064 nm continuous-wave laser diode that was intensity modulated, amplified, and frequency doubled in periodically poled lithium niobate. Measurements were made over a range of extinction by the addition of a Mg(OH)(2) and Al(OH)(3) suspension to the water path, and we were not able to observe any evidence of temporal pulse broadening. Results of Monte Carlo simulations over ocean water paths of several tens of meters indicate that optical communication data rates >1 Gbit/s can be supported and are compatible with high-capacity data transfer applications that require no physical contact.

Underwater Acoustic Communications and Networking: Recent Advances and Future Challenges

2008-03-01

Mandar Chitre , Shiraz Shahabudeen , Milica Stojanovic

The past 30 years have seen a growing interest in underwater acoustic communications because of its applications in marine research, oceanography, marine commercial operations, the offshore oil industry and defense. … The past 30 years have seen a growing interest in underwater acoustic communications because of its applications in marine research, oceanography, marine commercial operations, the offshore oil industry and defense. Continued research over the years has resulted in improved performance and robustness as compared to the initial communication systems. In this paper, we aim to provide an overview of the key developments in point-to-point communication techniques as well as underwater networking protocols since the beginning of this decade. We also provide an insight into some of the open problems and challenges facing researchers in this field in the near future.

On the relationship between capacity and distance in an underwater acoustic communication channel

2007-10-01

Milica Stojanovic

Path loss of an underwater acoustic communication channel depends not only on the transmission distance, but also on the signal frequency. As a result, the useful bandwidth depends on the … Path loss of an underwater acoustic communication channel depends not only on the transmission distance, but also on the signal frequency. As a result, the useful bandwidth depends on the transmission distance, a feature that distinguishes an underwater acoustic system from a terrestrial radio one. This fact influences the design of an acoustic network: a greater information throughput is available if messages are relayed over multiple short hops instead of being transmitted directly over one long hop. We asses the bandwidth dependency on the distance using an analytical method that takes into account physical models of acoustic propagation loss and ambient noise. A simple, single-path time-invariant model is considered as a first step. To assess the fundamental bandwidth limitation, we take an information-theoretic approach and define the bandwidth corresponding to optimal signal energy allocation -- one that maximizes the channel capacity subject to the constraint that the transmission power is finite. Numerical evaluation quantifies the bandwidth and the channel capacity, as well as the transmission power needed to achieve a pre-specified SNR threshold, as functions of distance. These results lead to closed-form approximations, which may become useful tools in the design and analysis of acoustic networks.

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Sparse Channel Estimation for Multicarrier Underwater Acoustic Communication: From Subspace Methods to Compressed Sensing

2009-12-11

Christian Berger , Shengli Zhou , James C. Preisig +1 more

In this paper, we investigate various channel estimators that exploit channel sparsity in the time and/or Doppler domain for a multicarrier underwater acoustic system. We use a path-based channel model, … In this paper, we investigate various channel estimators that exploit channel sparsity in the time and/or Doppler domain for a multicarrier underwater acoustic system. We use a path-based channel model, where the channel is described by a limited number of paths, each characterized by a delay, Doppler scale, and attenuation factor, and derive the exact inter-carrier-interference (ICI) pattern. For channels that have limited Doppler spread we show that subspace algorithms from the array processing literature, namely Root-MUSIC and ESPRIT, can be applied for channel estimation. For channels with Doppler spread, we adopt a compressed sensing approach, in form of Orthogonal Matching Pursuit (OMP) and Basis Pursuit (BP) algorithms, and utilize overcomplete dictionaries with an increased path delay resolution. Numerical simulation and experimental data of an OFDM block-by-block receiver are used to evaluate the proposed algorithms in comparison to the conventional least-squares (LS) channel estimator. We observe that subspace methods can tolerate small to moderate Doppler effects, and outperform the LS approach when the channel is indeed sparse. On the other hand, compressed sensing algorithms uniformly outperform the LS and subspace methods. Coupled with a channel equalizer mitigating ICI, the compressed sensing algorithms can effectively handle channels with significant Doppler spread.

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Research challenges and applications for underwater sensor networking

2006-01-01

John Heidemann , Wei Ye , Jack Wills +2 more

This paper explores applications and challenges for underwater sensor networks. We highlight potential applications to off-shore oilfields for seismic monitoring, equipment monitoring, and underwater robotics. We identify research directions in … This paper explores applications and challenges for underwater sensor networks. We highlight potential applications to off-shore oilfields for seismic monitoring, equipment monitoring, and underwater robotics. We identify research directions in short-range acoustic communications, MAC, time synchronization, and localization protocols for high-latency acoustic networks, long-duration network sleeping, and application-level data scheduling. We describe our preliminary design on short-range acoustic communication hardware, and summarize results of high-latency time synchronization

Leading-edge tubercles delay stall on humpback whale (Megaptera novaeangliae) flippers

2004-03-16

David Miklosovic , Mark M. Murray , Laurens E. Howle +1 more

The humpback whale (Megaptera novaeangliae) is exceptional among the baleen whales in its ability to undertake acrobatic underwater maneuvers to catch prey. In order to execute these banking and turning … The humpback whale (Megaptera novaeangliae) is exceptional among the baleen whales in its ability to undertake acrobatic underwater maneuvers to catch prey. In order to execute these banking and turning maneuvers, humpback whales utilize extremely mobile flippers. The humpback whale flipper is unique because of the presence of large protuberances or tubercles located on the leading edge which gives this surface a scalloped appearance. We show, through wind tunnel measurements, that the addition of leading-edge tubercles to a scale model of an idealized humpback whale flipper delays the stall angle by approximately 40%, while increasing lift and decreasing drag.

Data collection, storage, and retrieval with an underwater sensor network

2005-11-02

Iuliu Vasilescu , Keith Kotay , Daniela Rus +2 more

In this paper we present a novel platform for underwater sensor networks to be used for long-term monitoring of coral reefs and fisheries. The sensor network consists of static and … In this paper we present a novel platform for underwater sensor networks to be used for long-term monitoring of coral reefs and fisheries. The sensor network consists of static and mobile underwater sensor nodes. The nodes communicate point-to-point using a novel high-speed optical communication system integrated into the TinyOS stack, and they broadcast using an acoustic protocol integrated in the TinyOS stack. The nodes have a variety of sensing capabilities, including cameras, water temperature, and pressure. The mobile nodes can locate and hover above the static nodes for data muling, and they can perform network maintenance functions such as deployment, relocation, and recovery. In this paper we describe the hardware and software architecture of this underwater sensor network. We then describe the optical and acoustic networking protocols and present experimental networking and data collected in a pool, in rivers, and in the ocean. Finally, we describe our experiments with mobility for data muling in this network.

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Seaglider: a long-range autonomous underwater vehicle for oceanographic research

2001-01-01

Charles C. Eriksen , T. James Osse , R.D. Light +5 more

Seagliders are small, reusable autonomous underwater vehicles designed to glide from the ocean surface to a programmed depth and back while measuring temperature, salinity, depth-averaged current, and other quantities along … Seagliders are small, reusable autonomous underwater vehicles designed to glide from the ocean surface to a programmed depth and back while measuring temperature, salinity, depth-averaged current, and other quantities along a sawtooth trajectory through the water. Their low hydrodynamic drag and wide pitch control range allow glide slopes in the range 0.2 to 3. They are designed for missions in a range of several thousand kilometers and durations of many months. Seagliders are commanded remotely and report their measurements in near real time via wireless telemetry. The development and operation of Seagliders and the results of field trials in Puget Sound are reported.

Underwater acoustic sensor networks: research challenges

2005-02-03

Ian F. Akyildiz , Dario Pompili , Tommaso Melodia

A survey of techniques and challenges in underwater localization

2011-09-09

Hwee-Pink Tan , Roee Diamant , Winston K.G. Seah +1 more

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Underwater acoustic networks

2000-01-01

E. Sozer , Milica Stojanovic , J.G. Proakis

With the advances in acoustic modem technology that enabled high-rate reliable communications, current research focuses on communication between various remote instruments within a network environment. Underwater acoustic (UWA) networks are … With the advances in acoustic modem technology that enabled high-rate reliable communications, current research focuses on communication between various remote instruments within a network environment. Underwater acoustic (UWA) networks are generally formed by acoustically connected ocean-bottom sensors, autonomous underwater vehicles, and a surface station, which provides a link to an on-shore control center. While many applications require long-term monitoring of the deployment area, the battery-powered network nodes limit the lifetime of UWA networks. In addition, shallow-water acoustic channel characteristics, such as low available bandwidth, highly varying multipath, and large propagation delays, restrict the efficiency of UWA networks. Within such an environment, designing an UWA network that maximizes throughput and reliability while minimizing the power consumption becomes a very difficult task. The goal of this paper is to survey the existing network technology and its applicability to underwater acoustic channels. In addition, we present a shallow-water acoustic network example and outline some future research directions.

Adaptive multichannel combining and equalization for underwater acoustic communications

1993-09-01

Milica Stojanovic , Josko Catipovic , J.G. Proakis

A theoretically optimal multichannel receiver for intersymbol interference communication channels is derived, and its suboptimal versions with linear and decision feedback equalizer are presented. A practical receiver based on any … A theoretically optimal multichannel receiver for intersymbol interference communication channels is derived, and its suboptimal versions with linear and decision feedback equalizer are presented. A practical receiver based on any of these structures encounters difficulties in the underwater acoustic channels in which the extended time-varying multipath is accompanied by phase instabilities. A receiver that overcomes these problems by jointly performing adaptive mean-squared error diversity combining, multichannel carrier-phase synchronization and decision feedback equalization is proposed. Its performance is demonstrated on the experimental telemetry data from deep and shallow water long-range acoustic channels. Presented results indicate superior quality of coherent PSK and QAM reception obtained through joint equalization of very few channels.

Monte-Carlo-Based Channel Characterization for Underwater Optical Communication Systems

2012-12-07

Chadi Gabriel , Mohammad‐Ali Khalighi , Salah Bourennane +2 more

We consider channel characterization for underwater wireless optical communication (UWOC) systems. We focus on the channel impulse response and, in particular, quantify the channel time dispersion for different water types, … We consider channel characterization for underwater wireless optical communication (UWOC) systems. We focus on the channel impulse response and, in particular, quantify the channel time dispersion for different water types, link distances, and transmitter/receiver characteristics, taking into account realistic parameters. We use the Monte Carlo approach to simulate the trajectories of emitted photons propagating in water from the transmitter towards the receiver. During their propagation, photons are absorbed or scattered as a result of their interaction with different particles present in water. To model angle scattering, we use the two-term Henyey–Greenstein model in our channel simulator. We show that this model is more accurate than the commonly used Henyey–Greenstein model, especially in pure sea waters. Through the numerical results that we present, we show that, except for highly turbid waters, the channel time dispersion can be neglected when working over moderate distances. In other words, under such conditions, we do not suffer from any inter-symbol interference in the received signal. Lastly, we study the performance of a typical UWOC system in terms of bit-error-rate using the simple on–off-keying modulation. The presented results give insight into the design of UWOC systems.

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Underwater sensor networks: applications, advances and challenges

2011-11-28

John Heidemann , Milica Stojanovic , Michele Zorzi

This paper examines the main approaches and challenges in the design and implementation of underwater wireless sensor networks. We summarize key applications and the main phenomena related to acoustic propagation, … This paper examines the main approaches and challenges in the design and implementation of underwater wireless sensor networks. We summarize key applications and the main phenomena related to acoustic propagation, and discuss how they affect the design and operation of communication systems and networking protocols at various layers. We also provide an overview of communications hardware, testbeds and simulation tools available to the research community.

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Underwater acoustic communication channels: Propagation models and statistical characterization

2009-01-01

Milica Stojanovic , James C. Preisig

Acoustic propagation is characterized by three major factors: attenuation that increases with signal frequency, time-varying multipath propagation, and low speed of sound (1500 m/s). The background noise, although often characterized … Acoustic propagation is characterized by three major factors: attenuation that increases with signal frequency, time-varying multipath propagation, and low speed of sound (1500 m/s). The background noise, although often characterized as Gaussian, is not white, but has a decaying power spectral density. The channel capacity depends on the distance, and may be extremely limited. Because acoustic propagation is best supported at low frequencies, although the total available bandwidth may be low, an acoustic communication system is inherently wideband in the sense that the bandwidth is not negligible with respect to its center frequency. The channel can have a sparse impulse response, where each physical path acts as a time-varying low-pass filter, and motion introduces additional Doppler spreading and shifting. Surface waves, internal turbulence, fluctuations in the sound speed, and other small-scale phenomena contribute to random signal variations. At this time, there are no standardized models for the acoustic channel fading, and experimental measurements are often made to assess the statistical properties of the channel in particular deployment sites.

Soft Robotic Grippers for Biological Sampling on Deep Reefs

2016-01-20

Kevin C. Galloway , Kaitlyn P. Becker , Brennan Phillips +5 more

This article presents the development of an underwater gripper that utilizes soft robotics technology to delicately manipulate and sample fragile species on the deep reef. Existing solutions for deep sea … This article presents the development of an underwater gripper that utilizes soft robotics technology to delicately manipulate and sample fragile species on the deep reef. Existing solutions for deep sea robotic manipulation have historically been driven by the oil industry, resulting in destructive interactions with undersea life. Soft material robotics relies on compliant materials that are inherently impedance matched to natural environments and to soft or fragile organisms. We demonstrate design principles for soft robot end effectors, bench-top characterization of their grasping performance, and conclude by describing

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Underwater Optical Wireless Communication

2016-01-01

Hemani Kaushal , Georges Kaddoum

Underwater wireless information transfer is of great interest to the military, industry, and the scientific community, as it plays an important role in tactical surveillance, pollution monitoring, oil control and … Underwater wireless information transfer is of great interest to the military, industry, and the scientific community, as it plays an important role in tactical surveillance, pollution monitoring, oil control and maintenance, offshore explorations, climate change monitoring, and oceanography research. In order to facilitate all these activities, there is an increase in the number of unmanned vehicles or devices deployed underwater, which require high bandwidth and high capacity for information transfer underwater. Although tremendous progress has been made in the field of acoustic communication underwater, however, it is limited by bandwidth. All this has led to the proliferation of underwater optical wireless communication (UOWC), as it provides higher data rates than the traditional acoustic communication systems with significantly lower power consumption and simpler computational complexities for short-range wireless links. UOWC has many potential applications ranging from deep oceans to coastal waters. However, the biggest challenge for underwater wireless communication originates from the fundamental characteristics of ocean or sea water; addressing these challenges requires a thorough understanding of complex physio-chemical biological systems. In this paper, the main focus is to understand the feasibility and the reliability of high data rate underwater optical links due to various propagation phenomena that impact the performance of the system. This paper provides an exhaustive overview of recent advances in UOWC. Channel characterization, modulation schemes, coding techniques, and various sources of noise which are specific to UOWC are discussed. This paper not only provides exhaustive research in underwater optical communication but also aims to provide the development of new ideas that would help in the growth of future underwater communication. A hybrid approach to an acousto-optic communication system is presented that complements the existing acoustic system, resulting in high data rates, low latency, and an energy-efficient system.

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A Survey of Underwater Optical Wireless Communications

2016-10-19

Zhaoquan Zeng , Shu Fu , Huihui Zhang +2 more

Underwater wireless communications refer to data transmission in unguided water environment through wireless carriers, i.e., radio-frequency (RF) wave, acoustic wave, and optical wave. In comparison to RF and acoustic counterparts, … Underwater wireless communications refer to data transmission in unguided water environment through wireless carriers, i.e., radio-frequency (RF) wave, acoustic wave, and optical wave. In comparison to RF and acoustic counterparts, underwater optical wireless communication (UOWC) can provide a much higher transmission bandwidth and much higher data rate. Therefore, we focus, in this paper, on the UOWC that employs optical wave as the transmission carrier. In recent years, many potential applications of UOWC systems have been proposed for environmental monitoring, offshore exploration, disaster precaution, and military operations. However, UOWC systems also suffer from severe absorption and scattering introduced by underwater channels. In order to overcome these technical barriers, several new system design approaches, which are different from the conventional terrestrial free-space optical communication, have been explored in recent years. We provide a comprehensive and exhaustive survey of the state-of-the-art UOWC research in three aspects: 1) channel characterization; 2) modulation; and 3) coding techniques, together with the practical implementations of UOWC.

Underwater optical wireless communications, networking, and localization: A survey

2019-06-27

Nasir Saeed , Abdulkadir Çelik , Tareq Y. Al-Naffouri +1 more

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Exploration of underwater life with an acoustically controlled soft robotic fish

2018-03-21

Robert K. Katzschmann , Joseph DelPreto , Robert MacCurdy +1 more

A soft robot fish swims independently in three dimensions and enables studies of aquatic life in natural coral reef habitats. A soft robot fish swims independently in three dimensions and enables studies of aquatic life in natural coral reef habitats.

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Advancements in the field of autonomous underwater vehicle

2019-04-15

Avilash Sahoo , Santosha K. Dwivedy , P. S. Robi

Fundamentals and Applications of Ultrasonic Waves

2010-05-26

J.D.N. Cheeke

Ultrasonics: An Overview Introduction Ultrasonics in Nature Historical Development Physical Acoustics Low-Frequency Bulk Acoustic Wave Applications Surface Acoustic Waves Piezoelectric Materials High-Power Ultrasonics Medical Ultrasonics Acousto-Optics Underwater Acoustics and Seismology … Ultrasonics: An Overview Introduction Ultrasonics in Nature Historical Development Physical Acoustics Low-Frequency Bulk Acoustic Wave Applications Surface Acoustic Waves Piezoelectric Materials High-Power Ultrasonics Medical Ultrasonics Acousto-Optics Underwater Acoustics and Seismology Introduction to Vibrations and Waves Vibrations Wave Motion Bulk Waves in Fluids One-Dimensional Theory of Fluids Three-Dimensional Model Introduction to the Theory of Elasticity A Short Introduction to Tensors Strain Tensor Stress Tensor Thermodynamics of Deformation Hooke's Law Other Elastic Constants Bulk Acoustic Waves in Solids 1D Model of Solids Wave Equation in Three Dimensions Material Properties Viscoelastic Solids Finite Beams: Radiation, Diffraction, and Scattering Radiation Scattering Focused Acoustic Waves Radiation Pressure Doppler Effect Reflection and Transmission of Ultrasonic Waves at Interfaces Introduction Reflection and Transmission at Normal Incidence Oblique Incidence: Fluid-Fluid Interface Fluid-Solid Interface Solid-Solid Interface Rayleigh Waves Introduction Rayleigh Wave Propagation Fluid-Loaded Surface Lamb Waves Potential Method for Lamb Waves Fluid-Loading Effects Acoustic Waveguides Introduction: Partial Wave Analysis Waveguide Equation: SH Modes Lamb Waves Rayleigh Waves Layered Substrates Multilayer Structures Free Isotropic Cylinder Waveguide Configurations Crystal Acoustics Introduction Group Velocity and Characteristic Surfaces Piezoelectricity Cavitation and Sonoluminescence Bubble Dynamics Multibubble Sonoluminescence Single Bubble SL Bulk Acoustic Wave Transducers, Delay Lines, and Oscillators Bulk Acoustic Wave Transducers Bulk Acoustic Wave Delay Lines Quartz Crystal Resonators Silicon Oscillators Surface Acoustic Wave Transducers, Analog Signal Processing, and Mobile Applications Introduction Basic Components Materials and Technology Signal Processing Saw Applications Saw Wireless Communication to Coded Devices Microacoustics: RF MEMS, FBAR, and CMUT Introduction Overview of MEMS Technology Rf MEMS FBAR CMUT Capacitive Transducers Acoustic Sensors Thickness-Shear Mode Resonators Saw Sensors SH-Type Sensors Flexural Plate Wave Sensors CMUT Chem/Biosensor FBAR Liquid Sensors Thin-Rod Acoustic Sensors Gravimetric Sensitivity Analysis and Comparison Physical Sensing of Liquids Chemical Gas Sensors Taste Sensing: Electronic Tongue Biosensing Perspectives in Acoustic Sensors Focused Beam Acoustic Microscopy Introduction Resolution Acoustic Lens Design Contrast Mechanisms and Quantitative Measurements Applications of Acoustic Microscopy Near-Field Acoustic Microscopy Introduction Scanning Tunneling Microscope Atomic Force Microscope Ultrasonic AFM Contact Resonance Force Microscopy Mechanical Diode Effect Microscopy Acoustic Wave Probe Microscopy Other Probe Microscopies Perspectives Nondestructive Evaluation of Materials Introduction Surfaces Plates Layered Structures Adhesion Thickness Gauging Process Control Structural Health Monitoring Time Reversal Mirrors Non/Loosely Contacting NDE Techniques Laser Ultrasonics Electromagnetic Acoustic Transducers Air-Coupled Transducers Resonant Ultrasound Spectroscopy Appendix A: Bessel Functions Appendix B: Acoustic Properties of Materials Appendix C: Complementary Laboratory Experiments

An Overview of Recent Advances in Coordinated Control of Multiple Autonomous Surface Vehicles

2020-06-23

Zhouhua Peng , Jun Wang , Dan Wang +1 more

Autonomous surface vehicles (ASVs) are marine vessels capable of performing various marine operations without a crew in a variety of cluttered and hostile water/ocean environments. For complex missions, there are … Autonomous surface vehicles (ASVs) are marine vessels capable of performing various marine operations without a crew in a variety of cluttered and hostile water/ocean environments. For complex missions, there are increasing needs for deploying a fleet of ASVs instead of a single one to complete difficult tasks. Cooperative operations with a fleet of ASVs offer great advantages with enhanced capability and efficacy. Despite various application potentials, coordinated motion control of ASVs pose great challenges due to the multiplicity of ASVs, complexity of intravehicle interactions and fleet formation with collision avoidance requirements, and scarcity of communication bandwidths in sea environments. Coordinated control of multiple ASVs has received considerable attention in the last decade. This article provides an overview of recent advances in coordinated control of multiple ASVs. First, some challenging issues and scenarios in motion control of ASVs are presented. Next, coordinated control architecture and methods of multiple ASVs are briefly discussed. Then, recent results on trajectory-guided, path-guided, and target-guided coordinated control of multiple ASVs are reviewed in detail. Finally, several theoretical and technical issues are suggested to direct future investigations including network-based coordination, event-triggered coordination, collision-free coordination, optimization-based coordination, data-driven coordination of ASVs, and task-region-oriented coordination of multiple ASVs and autonomous underwater vehicles.

DBR: Depth-Based Routing for Underwater Sensor Networks

2008-01-01

Hai Yan , Zhijie Shi , Jun‐Hong Cui

Energy-Efficient MAC Protocol for Underwater Sensor Networks Using CSMA/CA, TDMA, and Actor–Critic Reinforcement Learning (AC-RL) Fusion

2025-06-25

Wazir Ur Rahman , Gang Qiao , Feng Zhou +5 more | Acoustics

Due to the dynamic and harsh underwater environment, which involves a long propagation delay, high bit error rate, and limited bandwidth, it is challenging to achieve reliable communication in underwater … Due to the dynamic and harsh underwater environment, which involves a long propagation delay, high bit error rate, and limited bandwidth, it is challenging to achieve reliable communication in underwater wireless sensor networks (UWSNs) and network support applications, like environmental monitoring and natural disaster prediction, which require energy efficiency and low latency. To tackle these challenges, we introduce AC-RL-based power control (ACRLPC), a novel hybrid MAC protocol that can efficiently integrate Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)-based MAC and Time Division Multiple Access (TDMA) with Actor–Critic Reinforcement Learning (AC-RL). The proposed framework employs adaptive strategies, utilizing adaptive power control and intelligent access methods, which adjust to fluctuating conditions on the network. Harsh and dynamic underwater environment performance evaluations of the proposed scheme confirm a significant outperformance of ACRLPC compared to the current protocols of FDU-MAC, TCH-MAC, and UW-ALOHA-QM in all major performance measures, like energy consumption, throughput, accuracy, latency, and computational complexity. The ACRLPC is an ultra-energy-efficient protocol since it provides higher-grade power efficiency by maximizing the throughput and limiting the latency. Its overcoming of computational complexity makes it an approach that greatly relaxes the processing requirement, especially in the case of large, scalable underwater deployments. The unique hybrid architecture that is proposed effectively combines the best of both worlds, leveraging TDMA for reliable access, and the flexibility of CSMA/CA serves as a robust and holistic mechanism that meets the desired enablers of the system.

Direct Forward-Looking Sonar Odometry: A Two-Stage Odometry for Underwater Robot Localization

2025-06-24

Wenhao Xu , Jianmin Yang , Jinghang Mao +3 more | Remote Sensing

Underwater robots require fast and accurate localization results during challenging near-bottom operations. However, commonly used methods such as acoustic baseline localization, dead reckoning, and sensor fusion have limited accuracy. The … Underwater robots require fast and accurate localization results during challenging near-bottom operations. However, commonly used methods such as acoustic baseline localization, dead reckoning, and sensor fusion have limited accuracy. The use of forward-looking sonar (FLS) images to observe the seabed environment for pose estimation has gained significant traction in recent years. This paper proposes a lightweight front-end FLS odometry to provide consistent and accurate localization for underwater robots. The proposed direct FLS odometry (DFLSO) includes several key innovations that realize the extraction of point clouds from FLS images and both image-to-image and image-to-map matching. First, an image processing method is designed to rapidly generate a 3-D point cloud of the seabed using FLS image, enabling pose estimation through point cloud matching. Second, a lightweight keyframe system is designed to construct point cloud submaps, which utilize historical information to enhance global pose consistency and reduce the accumulation of image-matching errors. The proposed odometry algorithm is validated by both simulation experiments and field data from sea trials.

A Reinforcement Learning-Based Path Optimization for Autonomous Underwater Vehicle Mission Execution in Dynamic Marine Environments

2025-06-24

Hyo‐Won Ahn , Seong Sik Ahn , Eun-Hwan Roh +6 more | Journal of KIISE

Underwater Modulation Classification Using Discrete Wavelet Transform and Genetic Algorithm

2025-06-24

Ali Çimen , Erdoğan Aldemir , Timur Düzenli̇ | International Journal of Pioneering Technology and Engineering

Underwater wireless optical communication systems face significant challenges due to the heterogeneous nature of the underwater environment and the attenuation of optical signals caused by absorption and scattering. These effects … Underwater wireless optical communication systems face significant challenges due to the heterogeneous nature of the underwater environment and the attenuation of optical signals caused by absorption and scattering. These effects restrict the data transfer capacity and transmission distance, resulting in communication errors. Different modulation techniques are used to minimize the effects of these parameters. Automatic modulation classification plays a critical role in terms of effective management of spectrum resources. In this study, underwater wireless optical communication channels are modulated with different modulation techniques, and the signals are transformed into the discrete wavelet space, resulting in approximation and detail coefficients that are used as feature vectors for training machine learning algorithms. In addition, optimized classification features are determined for different signal-to-noise ratios and different transmission distances using the genetic algorithm. The results show that the approximation and detail coefficient energies provide higher classification performance in the classification of modulated signals according to statistical features such as mean, variance, and standard deviation. According to simulation results, an average classification accuracy of 82% has been obtained using the proposed discrete wavelet transform and genetic algorithm-based technique, which demonstrates high classification accuracy for noisy underwater channels.

Vibration and noise reduction of underwater gliders with a novel wing integrating flexible cladding and phononic crystals

2025-06-24

Meijie Zhang , Peng Wang , Jun Chen +7 more | Ocean Engineering

Motion Characteristics Analysis of a Novel Autonomous Underwater Vehicle Deployable Capture Mechanism

2025-06-23

Guoxing Zhang , Renjie Luo , Jinwei Guo +2 more | Chinese Journal of Mechanical Engineering

Abstract The study of capture mechanisms with high capture adaptability is the key to improving the efficiency of autonomous underwater vehicle (AUV) retrieval and release. This study aims to develop … Abstract The study of capture mechanisms with high capture adaptability is the key to improving the efficiency of autonomous underwater vehicle (AUV) retrieval and release. This study aims to develop a capture mechanism for the launch and recovery of AUV and elucidate its kinematic characteristics. Initially, based on the principles of deployment and retraction for AUV capture movements, a design scheme for a novel foldable and deployable capture mechanism is proposed. Subsequently, a detailed analysis of the Degrees of Freedom (DoFs) for enveloping and grasping movements is conducted according to screw theory. Additionally, the structural design of the actuation units for the capture mechanism is thoroughly discussed. Motion screw topology diagram is utilized to construct the kinematic model. On this basis, kinematic simulation verification of the capture mechanism is performed. The theoretical analysis revealed that the DoF for enveloping and grasping movements are 6 and 2, respectively. By appropriately configuring the actuation mechanism, enveloping and grasping movements can be achieved with a single actuation. The displacement and velocity curves of the capture mechanism were smooth, with no interference occurring. Vibration test results validate the reliability of the capture mechanism. The research work provides a valuable reference for the development of novel capture equipment for AUVs.

Reinforcement Learning‐Based Model Predictive Path Integral Control for Obstacle Avoidance of Autonomous Underwater Vehicles

2025-06-23

Jintao Zhao , Tao Liu , Junhao Huang | Journal of Field Robotics

ABSTRACT Autonomous underwater vehicles (AUVs) face substantial challenges in obstacle avoidance due to the complex, dynamic nature of underwater environments and inherent sensing limitations. This study introduces a novel optimization … ABSTRACT Autonomous underwater vehicles (AUVs) face substantial challenges in obstacle avoidance due to the complex, dynamic nature of underwater environments and inherent sensing limitations. This study introduces a novel optimization framework that addresses these challenges by synergistically integrating advanced sampling strategies with reinforcement learning (RL) and model predictive path integral (MPPI) algorithms. The proposed framework strategically leverages the complementary strengths of both approaches: MPPI's proficiency in short‐term trajectory prediction combined with RL's exploratory capabilities and end‐to‐end training paradigm. This integration enables AUVs to rapidly adapt to environmental perturbations, make efficient real‐time obstacle avoidance decisions, continuously adjust to increasingly complex underwater scenarios, and achieve long‐term safe navigation objectives. To evaluate the efficacy of this RL‐MPPI hybrid approach, comprehensive numerical simulations were conducted across diverse underwater environmental conditions, encompassing both static and dynamic obstacles. The simulation results demonstrate enhanced adaptability and responsiveness in complex underwater environments, improved predictive accuracy and stability in obstacle avoidance maneuvers, and effective navigation through static and dynamic underwater scenarios while maintaining robust predictive characteristics. Quantitatively, the proposed method reduces the average cost value by 9.3% and average execution time by 2.9% compared with traditional MPPI in water‐free environments. Furthermore, in the presence of unknown water flow, it achieves a 7.2% reduction in average cost value and a 1.6% decrease in average execution time. This study contributes to the advancement of underwater robotics by offering a robust, adaptive, and computationally efficient approach to collision prevention for AUVs. The proposed framework demonstrates considerable promise for enhancing AUV capabilities in safe and efficient navigation through increasingly challenging underwater environments.

Reinforcement Learning Applications in Unmanned Underwater Vehicles: A Review

2025-06-23

Z. F. Tian , Sai Deng , Zhengxing Wu +1 more | Journal of Marine Science and Application

The Design and Optimization Technology of Propulsion Systems for Operative Underwater Robots

2025-06-20

Chen Guo | Applied and Computational Engineering

The importance of underwater robots is evident in ocean exploration, resource development, and environmental monitoring. However, the harsh underwater environment requires higher efficiency, stability, and intelligence from their propulsion systems. … The importance of underwater robots is evident in ocean exploration, resource development, and environmental monitoring. However, the harsh underwater environment requires higher efficiency, stability, and intelligence from their propulsion systems. The challenges faced by operational underwater robots today include low propulsion efficiency, poor adaptability to extreme environments, and a lack of sufficient autonomous control capabilities. To address these issues, this paper reviews the definition, requirements, core technologies, and key performance indicators of underwater robot propulsion systems by analyzing relevant literature from 2016 to 2024. It emphasizes optimization strategies aimed at enhancing propulsion efficiency, fault diagnosis and identification, reliability, durability, and adaptive control. Besides, it summarizes the current technical challenges and provides a reference for subsequent research. The results show that optimizing the propulsion system of operational underwater robots relies primarily on bionic design, new materials, adaptive control, deep learning, and fault diagnosis technologies to enhance propulsion efficiency, stability, durability, and environmental adaptability. However, optimizing the propulsion system involves challenges such as energy control, cost, and multi-objective optimization. Future research should prioritize efficient, low-energy propulsion, multi-modal perception, and intelligent adaptive control to advance underwater robot technology.

Design of a Cable Deployment and Retrieval System for a 1500-Meter Marine Winch

2025-06-20

Haobo Zhao , Hui Kong | Academic Journal of Science and Technology

To investigate the stress distribution and dynamic variation patterns of deep-sea winch systems during submersible cable towing operations and ensure operational safety, a novel dual-specification winch compatible with two distinct … To investigate the stress distribution and dynamic variation patterns of deep-sea winch systems during submersible cable towing operations and ensure operational safety, a novel dual-specification winch compatible with two distinct cable types was designed. The technical scheme, structural characteristics, and key parameters of the winch are introduced in detail. Simulation analyses are conducted based on both the physical model and the numerical simulation model established for the cable storage winch and cable management system. A systematic analysis of the stress and deformation of the cable storage winch and cable management system is carried out to verify the accuracy of the proposed models, providing a theoretical reference for the mechanical design and optimization of deep-sea winch systems.

A Q-learning-based trust model in underwater acoustic sensor networks (UASNs)

2025-06-19

Mehdi Hosseinzadeh , Amir Haider , Amir Masoud Rahmani +6 more | Ad Hoc Networks

Active stabilization optimization of underwater manipulator end-effector for the base swaying compensation

2025-06-19

Chong Shen , Yichen Wang , Fanghao Huang +2 more | International Journal of Intelligent Robotics and Applications

Finite-time prescribed performance with fixed-time disturbance rejection for underwater glider heading control

2025-06-19

Hanzhi Yang , Nina Mahmoudian | Ocean Engineering

OTA and DO-CCII Based Floating Memtranstor Emulator with Electronically Tunability Property

2025-06-19

Umut Engin Ayten , Muzaffer Çayır , Shahram Mınaeı +1 more | Circuits Systems and Signal Processing

Design and depth control of bionic mantis shrimp underwater robot with miniaturized low-cost sinking and floating system

2025-06-18

Yidong Xu , Gang Cheng , Chuanyu Wu +4 more | Ocean Engineering

Prescribed‐Time Disturbance‐Observing Chainlike Filtering Approach to Double‐Sided Event‐Driven Formation Tracking of Underactuated Underwater Vehicles With Kinematic and Kinetic Disturbances

2025-06-18

Hyeong Jin Kim , Sung Jin Yoo | International Journal of Robust and Nonlinear Control

ABSTRACT This paper investigates the distributed prescribed‐time formation tracking problem for uncertain multiple six‐degree‐of‐freedom underactuated underwater vehicles operating in dynamic state and input‐triggered environments. A critical challenge lies in addressing … ABSTRACT This paper investigates the distributed prescribed‐time formation tracking problem for uncertain multiple six‐degree‐of‐freedom underactuated underwater vehicles operating in dynamic state and input‐triggered environments. A critical challenge lies in addressing the nondifferentiability of event‐triggered state variables during recursive control design while estimating both kinematic and kinetic disturbances within a predefined time frame. To overcome these challenges, we propose a novel prescribed‐time disturbance‐observing chainlike filter (PDCF) capable of estimating intermittently triggered state signals and external disturbances in three‐dimensional operational spaces. Based on the PDCF, a distributed prescribed‐time formation tracking strategy is developed, featuring double‐sided event‐triggered mechanisms that dynamically update thresholds based on formation tracking errors. This approach ensures efficient control input and state update processes. Auxiliary signals are introduced into the control design to address the underactuated dynamics and input saturation problems further. A rigorous theoretical analysis guarantees the practical prescribed‐time stability of the closed‐loop system while preventing Zeno behavior. Finally, the comparative simulation results demonstrate the effectiveness and robustness of the proposed method, highlighting its capacity to achieve the desired formation tracking with enhanced resource efficiency.

Discrete-time nonlinear stochastic controller design for autonomous underwater vehicles under Bernoulli-distributed asynchronous time delays

2025-06-18

L. Guo , Jian Ma , Fang Wang | Ships and Offshore Structures

Fast Swimming Robot Fish Under Countercurrent, Complex Trajectory, and Heavy Load Environments

2025-06-17

Zhaohui Yang , Yixiang He , Haoran Xing +2 more | Journal of Field Robotics

ABSTRACT The present study proposes a new design for a robot fish which is propelled by periodic vibrations of a flexible‐soft coupled beam. This unique, flexible‐soft coupled beam can display … ABSTRACT The present study proposes a new design for a robot fish which is propelled by periodic vibrations of a flexible‐soft coupled beam. This unique, flexible‐soft coupled beam can display the first and second‐order mode oscillations, which are capable of effectively mimicking the swings of the fish tail, resulting in fast swimming of the robot fish. Firstly, the nonlinear dynamic model for the coupled beam is established based on the absolute node coordinate formulation. The effect of length and stiffness parameters on natural frequency and mode shape of the coupled beam is explored to obtain the linear dynamic characteristics of the fish tail. To reach the maximum vibration amplitude, the optimal values for position, frequency, and magnitude of the applied force and the length and stiffness parameters are determined. In the following, the control system uses a communication mode to receive signals from a wireless communication module, and an inertial sensor is designed. The fuzzy PID algorithm is employed to control vibrations of the coupled beam to realize the swimming forward and turning around of the robot fish. Finally, through 3D printing and the opening mold technique, the robot fish is fabricated with an overall size of 130 × 125 × 70 mm 3 . Swimming experiments are performed to display the propulsion speed and force of the robot fish. It shows that the swimming speed of 1.17 BL/s can be achieved, which is much higher than most of the previously designed robot fish in BCF mode. In addition, the experiments indicate that the robot fish has an excellent swimming performance even in countercurrent, complex trajectories, and heavy load environments. The present study offers a delicate design and a precise theory of the flexible‐soft coupled beam‐based fish tail for fast swimming of the robot fish.

Research on the Elastic Loss Characteristics of Acoustic Echoes from Underwater Corner Reflector

2025-06-17

Yi Luo , Dawei Xiao , Jingzhuo Zhang +1 more | Sensors

The underwater corner reflector is a "concave" elastic structure, and its acoustic echo exhibits large elastic loss, which affects its practical use. To study the acoustic echo elastic loss characteristics … The underwater corner reflector is a "concave" elastic structure, and its acoustic echo exhibits large elastic loss, which affects its practical use. To study the acoustic echo elastic loss characteristics of underwater corner reflectors, based on the characteristics of small concave elastic structures of underwater corner reflectors, theoretical calculations were performed using the method of a combination of finite element and boundary element. Taking the underwater rigid corner reflector as the benchmark, the acoustic echo differences between similar types of underwater elastic corner reflectors were compared. The regular acoustic echo elastic loss of underwater corner reflectors was analyzed, and verified through pool experiments. The results show that, whether single-grid or multi-grid corner reflector, the actual acoustic echoes of underwater corner reflectors conform to the characteristics of elastic bodies, which differ significantly from rigid bodies and exhibit obvious elastic loss. The elastic loss mainly manifests as reduced target strength (TS), narrower directional pattern width, and poorer frequency stability of target strength, which is detrimental to practical use. This study provides assistance in proposing targeted methods to suppress elastic loss.

Enabling the Ocean Internet of Things with Renewable Marine Energy

2025-06-16

Mathew Topper , Nicolas Jarnoux , Ronan Costello +3 more | International Marine Energy Journal

Marine renewable energy can play an integral role in reducing the cost and complexity of collecting data from the oceans and enhancing its exploitation. The processing and transmission of data … Marine renewable energy can play an integral role in reducing the cost and complexity of collecting data from the oceans and enhancing its exploitation. The processing and transmission of data at sea may be modelled as an 'internet of things' (IoT) application. The 'thing' is any offshore device which can collect and process data in situ, while the 'internet' represents the medium for transmitting data. IoT is differentiated from other internet-based communication paradigms by the constraints on the system. These constraints are typically limited energy budgets and computing power, intermittent and low-bandwidth connectivity, and limited physical access. While land-based IoT applications are already well served by a wide selection of hardware and software components, the needs of offshore IoT applications are not well served. Utilizing marine energy can advance the adoption of IoT at sea by providing in-situ energy generation, whilst also benefitting from the same technology. The Sustainable Energy Authority of Ireland funded 'BlueBox' project aims to overcome barriers to entry for applying IoT technologies to offshore sensing by developing Ocean IoT (OIoT) hardware and software solutions. Features of the BlueBox system include modular offshore-focussed hardware, no-code configuration and control of peripherals (such as sensors and actuators), duplex transmission of data using multiple media, serverless cloud server architecture, and an edge computing framework. This paper presents an overview of BlueBox, tank tests for system validation of a prototype wave-energy powered ocean-observing platform, and a discussion of future applications of the technology.

Distributed collaborative seabed terrain matching method using distance measurements for autonomous underwater vehicles

2025-06-14

Shijie Wu , Shuai Chang , Kaixuan Wang +2 more | Ocean Engineering

AI-Driven Adaptive Communications for Energy-Efficient Underwater Acoustic Sensor Networks

2025-06-14

Aziz Ur Rehman , Laura Galluccio , Giacomo Morabito | Sensors

Underwater acoustic sensor networks, crucial for marine monitoring, face significant challenges, including limited bandwidth, high delay, and severe energy constraints. Addressing these limitations requires an energy-efficient design to ensure network … Underwater acoustic sensor networks, crucial for marine monitoring, face significant challenges, including limited bandwidth, high delay, and severe energy constraints. Addressing these limitations requires an energy-efficient design to ensure network survivability, reliability, and reduced operational costs. This paper proposes an artificial intelligence-driven framework aimed at enhancing energy efficiency and sustainability in applications of marine wildlife monitoring in underwater sensor networks, according to the vision of implementing an underwater acoustic sensor network. The framework integrates intelligent computing directly into underwater sensor nodes, employing lightweight AI models to locally classify marine species. Transmitting only classification results, instead of raw data, significantly reduces data volume, thus conserving energy. Additionally, a software-defined radio methodology dynamically adapts transmission parameters such as modulation schemes, packet length, and transmission power to further minimize energy consumption and environmental disruption. GNU Radio simulations evaluate the framework effectiveness using metrics like energy consumption, bit error rate, throughput, and delay. Adaptive transmission strategies implicitly ensure reduced energy usage as compared to non-adaptive transmission solutions employing fixed communication parameters. The results illustrate the framework ability to effectively balance energy efficiency, performance, and ecological impact. This research contributes directly to ongoing development in sustainable and energy-efficient underwater wireless sensor network design and deployment.

Underwater glider persistent coverage using deep reinforcement learning for ocean observation

2025-06-14

Jiayi Liu , Xiang Jin , Jin Yao +2 more | Ocean Engineering

Cryptography-Based Secure Underwater Acoustic Communication for UUVs: A Review

2025-06-13

Qian Zhou , Qing Ye , Chengzhe Lai +1 more | Electronics

Unmanned Underwater Vehicles (UUVs) play an irreplaceable role in marine exploration, environmental monitoring, and national defense. The UUV depends on underwater acoustic communication (UAC) technology to enable reliable data transmission … Unmanned Underwater Vehicles (UUVs) play an irreplaceable role in marine exploration, environmental monitoring, and national defense. The UUV depends on underwater acoustic communication (UAC) technology to enable reliable data transmission and support efficient collaboration. As the complexity of UUV missions has increased, secure UAC has become a critical element in ensuring successful mission execution. However, underwater channels are inherently characterized by high error rates, limited bandwidth, and signal interference. These problems severely limit the efficacy of traditional security methods and expose UUVs to the risk of data theft and signaling attacks. Cryptography-based security methods are important means to protect data, effectively balancing security requirements and resource constraints. They provide technical support for UUVs to build secure communication. This paper systematically reviews key advances in cryptography-based secure UAC technologies, focusing on three main areas: (1) efficient authentication protocols, (2) lightweight cryptographic algorithms, and (3) fast cryptographic synchronization algorithms. By comparing the performance boundaries and application scenarios of various technologies, we discuss the current challenges and critical issues in underwater secure communication. Finally, we explore future research directions, aiming to provide theoretical references and technical insights for the further development of secure UAC technologies for UUVs.

Estimation of Manoeuvrability and Depth Control for an Underwater Vehicle near Free Surface by Free-Running Model Tests

2025-06-13

Kunhang Yun , Sungrok Cho , Yeongjun Lee +1 more | Journal of the Society of Naval Architects of Korea

Aquisição e leitura dos parâmetros contidos na água para aplicação em um sistema hidropônico

2025-06-12

Igor da Silva Ferreira , Moises Hamsses Sales de Sousa | DELOS Desarrollo Local Sostenible

Este trabalho aborda o desenvolvimento e a aplicação de um sistema automatizado de baixo custo para o cultivo hidropônico, com foco em regiões de clima tropical. A introdução destaca a … Este trabalho aborda o desenvolvimento e a aplicação de um sistema automatizado de baixo custo para o cultivo hidropônico, com foco em regiões de clima tropical. A introdução destaca a importância de otimizar os processos de cultivo para enfrentar desafios como o desperdício de recursos e a variação climática. O objetivo do estudo foi criar um protótipo que monitorasse automaticamente variáveis cruciais, como temperatura, pH, umidade e turbidez da solução nutritiva. A metodologia envolveu a construção e programação de um microcontrolador ATMEGA 328p, integrado a sensores específicos para coletar dados em tempo real do sistema. Os resultados demonstraram que o protótipo foi eficaz em analisar os parâmetros da água para o desenvolvimento das plantas, contribuindo para um aumento da produtividade e uma economia significativa de água. O estudo concluiu que a automação do cultivo hidropônico é uma solução viável e vantajosa, especialmente para pequenos e médios agricultores, promovendo maior sustentabilidade e eficiência no uso dos recursos. As limitações identificadas incluem a necessidade de conhecimento técnico para operação e a aplicação restrita a ambientes controlados. Pesquisas futuras podem explorar a integração com tecnologias avançadas, como a Internet das Coisas e inteligência artificial, para aprimorar ainda mais a funcionalidade do sistema.

Trajectory tracking control of autonomous underwater vehicles based on a predefined time control strategy

2025-06-12

Yang Liu , Longjin Wang , Shun An +2 more | Measurement Science and Technology

Abstract This paper investigates the problem of trajectory tracking control of underactuated autonomous underwater vehicles (AUVs) with predefined time convergence. To this end, a predefined time nonlinear disturbance observer (PTNDO) … Abstract This paper investigates the problem of trajectory tracking control of underactuated autonomous underwater vehicles (AUVs) with predefined time convergence. To this end, a predefined time nonlinear disturbance observer (PTNDO) is designed with the aim of accurately estimating unknown external disturbances. This observer is capable of capturing the dynamic influences on the AUV in real time to support the subsequent control strategy. By setting the time parameters reasonably, the convergence time of the system can be set in advance, thus ensuring that the desired tracking effect is achieved within a specific time. In addition, a predefined time backstepping controller (PTBC) is designed for the problem of AUV trajectory tracking. Theoretical analysis shows that the upper limit of its convergence time is only determined by a constant, which simplifies the parameter tuning process and enhances the practicability compared with the existing finite/fixed time control methods. The effectiveness and superiority of the proposed method are verified through further simulation studies, which show that the control strategy has good trajectory tracking performance.

Design of hand-Sized Torpedo-Like Fish Robot with the Dynamics and Hydrodynamics Analysis

2025-06-06

Farah Abbas Naser | Journal of Applied Nonlinear Dynamics

Biogeography-Based Optimization Algorithm for Cooperative Task Allocation and Search and Rescue of Unmanned Boats

2025-06-04

Xiangchu Feng , Bowei Xing , Dong Han | Advances in transdisciplinary engineering

This paper addresses the problem of path planning and task allocation for cooperative search and rescue (SAR) missions of unmanned boats in a typical SAR scenario. Firstly, a system model … This paper addresses the problem of path planning and task allocation for cooperative search and rescue (SAR) missions of unmanned boats in a typical SAR scenario. Firstly, a system model for cooperative SAR of unmanned boats is established, including environmental model, task model, unmanned boat model, and task model, to the complex maritime SAR environment and task requirements. Then, the task allocation process is divided into two core stages, which are applied to the cooperative SAR mission of unmanned boats Through simulation experiments, the performance of BLSA algorithm and other intelligent optimization algorithms in terms of search and rescue efficiency, path length, and computation time is compared and. The results show that the BLSA algorithm has significant advantages in solving the cooperative SAR problem of unmanned boats, which can improve the search and rescue efficiency, shorten search and rescue time, and provide new solutions for maritime rescue tasks.