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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...
Underwater Wireless Sensor Networks (UWSNs) are expected to support a variety of civilian and military applications. Sensed data can only be interpreted meaningfully when referenced to the location of the sensor, making localization an important problem. In terrestrial WSNs, this can be achieved through a series of message exchanges (via RF communications) between each sensor and Global Positioning...
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,...
Mobile swarms of autonomous underwater vehicles (AUV) have exciting potential for extending current AUV applications and adding new possibilities to the working environment of the oceans. For swarm operations to occur, fast reliable communication between all vehicles within the swarm is needed. The challenge for underwater communication is the very different and unique characteristics of the channel...
Underwater sensor network (USN) enables various services implemented over terrestrial wireless sensor network previously and underwater robot control service is one of the applications of USN. For wirelessly controlling an underwater robot, development of an underwater acoustic modem for transmitting robot control frame as well as analysis of the robot control protocol should be carried out properly...
The research being conducted in the Center for Secure and Resilient Maritime Commerce (CSR), a DHS National Center of Excellence for Port Security examines some basic science issues and emerging technologies to improve the security of ports and inland waterways, as well as coastal and offshore operations. This research follows a layered approach utilizing above water and underwater surveillance techniques...
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...
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...
Hermes is a two-way half-duplex underwater acoustic modem developed to transfer large amounts of information from an underwater asset to a surface operator, while being able to send command-and-control information to the underwater asset. In addition, this communication system must operate in very challenging environments such as busy ports and very shallow waters. Hermes must also provide the ability...
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,...
Communication underwater is severely limited when compared to communications in air because water is essentially opaque to electromagnetic radiation except in the visible band. Even in the visible band, light penetrates only a few hundred meters in the clearest waters and much less in waters made turbid by suspended sediment or high concentrations of marine life. Consequently, acoustic techniques...
This paper discusses the autonomy framework proposed for the mobile instruments such as Autonomous Underwater Vehicles (AUVs) and gliders. Paper focuses on the challenges faced by these clusters of mobile platform in executive tasks such as adaptive sampling in the hostile underwater environment. Collaborations between these mobile instruments are essential to capture the environmental changes and...
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...
Combination of optical and acoustic sensors to compensate the strengths and weaknesses of each sensor modality is a topic of increasing interest in applications involving autonomous underwater vehicles (AUV). In this work, an opti-acoustic system composed by a single camera and a multibeam sonar is proposed, providing a simulation environment to validate its potential use in 3D reconstruction. Since...
This paper presents two novel cooperative adaptive algorithms for the management of autonomous underwater vehicles (AUV) as mobile nodes of an ad- hoc underwater network. The proposed approaches are distributed and take explicitly into account the communication constraints among the agents. The overall mission goal for the AUV team is to defend an asset using detection sonars while maintaining the...
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...
Underwater Wireless Sensor Networks (UWSN) experience severe communication problems due to large acoustic or electromagnetic (EM) signal attenuation. The propagation of acoustic signals in submarine media is possible with very low frequency signal carriers only, therefore reduced bandwidth, low transmission rates, thus extending transmission duration and diminishing battery life. Requirements to increase...
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...
In this paper, we propose a cooperative localization algorithm based on extended Kalman filter (EKF) for multiple underwater vehicles. Research on cooperative localization of multiple underwater vehicles is an important topic to solve the navigation problem in long range and deep sea. We investigate the improvement in navigation accuracy. In the cooperative localization structure, one master underwater...
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...
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