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This paper presents an integrated underwater navigational algorithm for autonomous underwater vehicles using two movable surface acoustic reference stations which can transmit data packet to the AUV via acoustic modem with synchronous timer. This paper proposes a measurement model with the two range measurements that can improve the performance of an IMU-DVL (inertial measurement unit - Doppler velocity...
In order to get reliable communication no matter under the water or above the surface, a kind of multi channel and distributed wireless communication network architecture for UUVs was presented. This network architecture includes underwater communication, surface communication and internal communication. Underwater communication is acoustic modem, and the surface communication consists of RF, Wi-Fi,...
In an underwater environment signal propagation for the acoustic channel is subject to major multipath effect. Therefore, most underwater communication schemes require that the position of the transmitter or receiver is fixed while using directional antennas in order to ensure high signal-to-noise ratio. However, such a requirement hinders node discovery and ad-hoc formation of underwater networks...
In this paper, we address the challenging topic of target detection and tracking in underwater environments, proposing a behavior-based algorithm suitable for both fixed and moving targets. Taking into account the stringent constraints of the acoustic underwater channel, we apply this method to fleets of collaborative AUVs. The resulting control strategy is able to benefit from the behavior-based...
Cooperative navigation for multi-UUV is localizing all members of a team of UUVs by proprioceptive and exteroceptive sensors through acoustic link among UUVs. In the Leader-Fellow structure, the master UUV is equipped with high accuracy sensors, the slave UUV is equipped with low precision sensors added with underwater sonar which provide relative observations between UUVs. The slaver gets the position...
Doppler Velocity Logs (DVLs) have become increasingly popular as navigation tools on remotely-operated vehicles, autonomous underwater vehicles, and human-occupied vehicles for over a decade. Using acoustic measurements to capture bottom tracking velocity measurements, DVLs can provide updated velocities which can in turn be used to calculate distance traveled. Thus, DVLs can perform as fundamental...
In this paper, we compare communication schemes in scenarios of interest for underwater networks where multiple nodes collaborate towards the accomplishment of a target detection and tracking task. We consider two specific cases: in Scenario 1, a mobile Autonomous Underwater Vehicle (AUV) i) collects data from a set of fixed sensors deployed on the seafloor or ii) transmits data to the same nodes...
We consider cooperative positioning using acoustic range measurements for underwater sensor networks, including networks formed by autonomous unmanned underwater vehicles (UUVs). Severe multipath scattering from the seabed and ocean surface can result in inaccurate range measurements. In an inhomogeneous medium, such as sea water, the direct path is not necessarily the strongest path or the first...
The maximum potential for underwater exploration rests within the use of multiple Autonomous Underwater Vehicles (AUVs) and tasks involving human diver-AUV coordination. Such tasks require dependable underwater wireless communications, which normally utilize the rapidly varying acoustic channel. Rigorous testing of underwater acoustic communication systems is necessary to develop a dependable network,...
Underwater testbeds are key tools for performance evaluation of underwater communication and coordination algorithms to enable swarming of autonomous vehicles. We describe a demonstration of underwater vehicle team formation and steering algorithms using our underwater testbed. The tesdbed allows the user to configure ocean currents and underwater communication parameters so to study properties of...
Today a large number of autonomous underwater vehicles (AUVs) are evaluated or operated all over the world. Most of them use their own control systems created by the vehicle's manufacturer or scientists of different research areas. The Fraunhofer Application Center System Technology currently owns three underwater vehicles (both AUVs and remotely operated vehicles, ROVs), a forth is under development...
Missions involving multiple Autonomous Underwater Vehicles (AUVs) are gaining increasing popularity with the advent of better control mechanisms and availability of acoustic modems that allow for cooperative networked tasks to be carried out by Unmanned Underwater Vehicles (UUVs). However, high costs associated with offshore testing and the lack of useful tools to accurately simulate multi-AUV tasks...
Unmanned underwater vehicles have various missions within civilian, military and academic sectors. They have the ability to explore areas unavailable to manned assets and to perform duties that are risky to humans. In particular, UUVs have the ability to perform bearings-only tracking in shallow areas near shorelines. This article compares a Logarithmic Polar Coordinates EKF (LPC-EKF) and Logarithmic...
We consider the problem of reconstructing 3D models of underwater objects from multiview images and propose a low complexity algorithm to achieve this without loss in accuracy as compared to existing work. We utilize bicubic interpolation as a substitute for Gaussian decomposition to arrive at multiresolution images. We use Kolmogorov modeling to generate disparity maps from various views and hence...
We wish to exploit the complementary characteristics of marine sensor networks and autonomous vehicles through interaction and cooperation to achieve tasks that neither can accomplish alone - large-scale, long duration perception of the environment and response to changes in that environment. We outline and experimentally evaluate a new programming and communications framework that supports the integration...
Underwater communications are critical to applications of remotely operated vehicles (ROV) and autonomous underwater vehicles (AUV) to both entertainment and research purposes. Among others, underwater video transmission is rather difficult due to the demand of high data rate (bandwidth) transmission through the water medium which leads to large attenuation for electromagnetic (EM) waves. In this...
This paper presents and experimentally validates two closed-form underwater acoustic positioning methods with experimental data from an Ultra-Short Base Line (USBL) system developed from scratch. The prototype underwater positioning device that is being developed is planned to be extensively used within the framework of the European TRIDENT project. Both positioning methods compute the localization...
This paper reports the development and experimental evaluation of a novel navigation system for underwater vehicles that employs Doppler sonar, synchronous clocks, and acoustic modems to achieve simultaneous acoustic communication and navigation. The system reported herein, which is employed to renavigate the vehicle in post-processing, forms the basis for a vehicle-based real-time navigation system...
As unmanned marine vehicles rapidly establish themselves as powerful and reliable tools in an ever increasing number of tasks, the focus of research has shifted towards simultaneous operation of coordinated fleets of vehicles. The GREX project joins this development effort with a comprehensive and ambitious development plan. This paper gives account of the first sea trials experience involving a fleet...
Swarms of underwater autonomous vehicles (UAVs) are being increasingly used in civilian and military applications. Formations of UAVs are being utilized to detect mine-like objects and oilfields, collect water quality information, detect intruders, and in navigation assistance applications, among others. This paper introduces a new data link layer for underwater communications suitable for non-synchronized...
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