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The autonomous underwater vehicle has proven to be a useful tool for ocean research. However detailed seafloor observations such as microscopic analysis of sand grain structure or study of microbial colonies require a platform with stable footing on the seafloor, which cannot be provided by a cruising type AUV. In this research the authors propose a new class of AUV, capable of landing to provide...
This paper describes an effort to adapt a fleet of autonomous underwater vehicles (AUVs) for the measurement of the magnetic signature of surface ships. Currently, two such vehicles have been upgraded with the necessary navigation and measurement hardware to perform magnetic measurements. Initial testing has been performed at the Naval Acoustic Research Detachment at Lake Pend Oreille, Idaho. Two...
Developing algorithms and parameterizing controllers for autonomous underwater vehicles are tasks which needs excessive testing. Therefore, we developed an environment and a tool chain for these difficult and mostly expensive tasks. This tool chain consist of different steps for implementing algorithms from the idea to mission ready. These steps include rapid prototyping, simulation testing, testing...
The thermocline is a vertical transition layer in the water column with a strong impact on marine biology, since it affects phytoplankton concentration and, hence, primary production. AUVs can play an important role in understanding this relationship, by sampling the relevant data, usually describing yo-yo patterns spanning the whole water column. In this paper we describe a reactive behavior implemented...
This paper discusses possible behaviours for single and multiple AUVs in bistatic and multistatic active sonar configurations respectively. With a mixture of theoretical exposition, simulation and actual sea trial results the possibility of making a mobile networked system which behaves in an optimal manner is discussed. For a single AUV it is shown that an information theoretic approach yields a...
This paper presents a novel approach based on Jacobi shape theory and geometric reduction for formation control of autonomous underwater vehicles (AUVs). We consider a three degree-of-freedom (DOF) dynamic model for the horizontal motion of each AUV that has control inputs over surge force and yaw moment. By using the Jacobi transform, the horizontal dynamics of AUVs are expressed as dynamics for...
The paper studies the observability properties of the relative localization of two Autonomous Underwater Vehicles (AUVs) equipped with depth sensors, linear/angular velocity sensors, and communication devices with range measurement. The conditions that ensure observability of the linearized model and locally weak observability of the nonlinear system are derived. An Extended Kalman Filter is then...
A novel artificial-potential approach is presented for planning the minimum-exposure paths of multiple vehicles in a dynamic environment containing multiple mobile sensors, and multiple fixed obstacles. This approach presents several advantages over existing techniques, such as the ability of computing multiple minimum-exposure paths online, while avoiding mutual collisions, as well as collisions...
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...
To take measurements in space and time from the undersampled vast ocean, it is necessary to employ multiple autonomous underwater vehicles, such as gliders, that communicate and coordinate with each other. These vehicles need to form a team in a specific formation, steer through the 3D region of interest, and take application-dependent measurements such as temperature and salinity. In this paper,...
Due to its significant potential applications, underwater chemical plume exploration and source localization via an autonomous underwater vehicle (AUV) is currently a hot subject both in AUV and oceanic engineering research communities. Chemical plume including buoyant stem and non-buoyant part such as deep-sea hydrothermal plume is a typical dynamic 3D feature in the ocean environment; therefore,...
This paper addresses the problem of synchronized path following of multiple under-actuated autonomous underwater vehicles (AUVs). The dedicated control laws are categorized into two envelopes, one is steering individual vehicle to trace along predefined paths, and the other is ensuring tracked paths of multiple vehicles to be synchronized, by means of decentralized speed adaption under the constraints...
Autonomous Underwater Vehicle (AUV) are moving to a new phase with the development of light intervention systems. New vehicles will be equipped with lightweight manipulators and operate around subsea infrastructures. One of the key capabilities to safely perform such mission is robust and accurate autonomous localisation, i.e. the ability for the AUV to estimate correctly its position and orientation...
This work proposes a control algorithm to stabilize a circular formation of AUVs tracking a time-varying center. We also consider the problem of uniform distribution of all the agents along the circle from two approaches: all-to-all and limited communication. We tackle with this communication constraint using a cooperative control strategy which includes the Laplacian matrix of the communication graph...
This paper presents the design and implementation of a mission control system (MCS) for an autonomous underwater vehicle (AUV) based on Petri nets. In the proposed approach the Petri nets are used to specify as well as to execute the desired autonomous vehicle mission. The mission is easily described using an imperative programming language called mission control language (MCL) that formally describes...
Although the equations describing the longitudinal motions of autonomous underwater vehicles are typically nonlinear, the linearized equations are still employed to design the depth controller by the traditional analysis methods in engineering for the sake of simplicity. The reduction of the nonlinearity losts the dynamics near the singular points which may be responsible for the sudden climb or dive...
A motion control strategy consisting of both position and speed control was designed for different work assignments of Autonomous Underwater Vehicles (AUV). To provide a form that will be suitable for simulation and control purposes, a general mathematical model of underwater vehicles was derived based on the six degrees of freedom nonlinear equations of motion. An improved S-surface controller based...
The paper describes a localization system for autonomous underwater vehicles (AUV). It uses a DVL (Doppler velocity log) sensor and AHRS (attitude and heading reference system) sensor to measure AUV's depth, attitude and velocities relative to the bottom. A mechanically scanning imaging sonar (MSIS) is employed to obtain acoustic images of objects in underwater environment. In order to estimate optimally...
In this paper, an improved Takagi-Sugeno (T-S) Fuzzy Neural Network (FNN) based on modified learning is proposed for the motion control of Autonomous Underwater Vehicles (AUV). Aiming to improve the control precision and adaptability of T-S fuzzy model, a fuzzy objective is used to update the fuzzy rules and the proportion factor on-line. A modified learning of network is developed by back-propagating...
Path planning is basis for any autonomous underwater vehicle to implement completely cruising in subsea environment and path tracking is important technology as well, especially for multi-AUV (Autonomous underwater vehicle) cruising with a fleet formate. In this paper, algorithms path planning and path tracking are addressed for an open frame AUV. Fast Marching algorithm is applied to solve problems...
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