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- Title
- Hydrodynamic analysis of underwater bodies for efficient station keeping in shallow waters with surface waves.
- Creator
- Bradley, Matthew, Ananthakrishnan, Palaniswamy, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
To determine the effect of body shape on the response of underwater vehicles to surface waves in shallow water, the wave radiation hydrodynamic forces are evaluated for a family of (i) prolate spheroidal hull forms and (ii) cylindrical bodies with hemispherical nose and conical tail sections by systematically varying the geometric parameters but keeping displacement constant. The added-mass and wave damping coefficients are determined using a frequency-domain, simple-source based boundary...
Show moreTo determine the effect of body shape on the response of underwater vehicles to surface waves in shallow water, the wave radiation hydrodynamic forces are evaluated for a family of (i) prolate spheroidal hull forms and (ii) cylindrical bodies with hemispherical nose and conical tail sections by systematically varying the geometric parameters but keeping displacement constant. The added-mass and wave damping coefficients are determined using a frequency-domain, simple-source based boundary integral method. Results are obtained for a range of wave frequencies and depths of vehicle submergence all for a fixed water depth of 10 m. With the wave exciting force and moment determined using the Froude-Krylov theory, the response transfer functions for heave and pitch are then determined. The heave and pitch response spectra in actual littoral seas are then determined with the sea state modeled using TMA spectral relations. Results show that vehicle slenderness is a key factor affecting the hydrodynamic coefficients and response. The results show two characteristics that increase the radiation hydrodynamic forces corresponding to heave and pitch motions: namely, vehicle length and further-away from mid-vehicle location of the body shoulder. The opposite is true for the oscillatory surge motion. By utilizing these observed characteristics, one can design the lines for maximum radiation forces and consequently minimum hull response for the critical modes of rigid-body motion in given waters and vehicle missions. In the studies carried out in the thesis, a hull with a long parallel middle body with hemispherical nose and conical tail sections has better heave and pitch response characteristics compared prolate spheroid geometry of same volume. The methodology developed herein, which is computationally efficient, can be used to determine optimal hull geometry for minimal passive vehicle response in a given sea.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00004084, http://purl.flvc.org/fau/fd/FA00004084
- Subject Headings
- Oceanographic submersibles -- Hydrodynamics, Surface waves (Oceanography) -- Mathematical models, Wave motion, Theory of
- Format
- Document (PDF)
- Title
- Damage detection for autonomous underwater vehicles.
- Creator
- Rae, Graeme John Stuart., Florida Atlantic University, Dunn, Stanley E., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A method of on-line monitoring AUV onboard systems is described. This algorithm determines deviations from normal operating conditions based on a damage level calculated from recursive least squares system identification performed on the system under consideration, followed by a gradient detection technique which extracts significant changes in identified model parameters System damage types are characterized together with likely system responses to such failures. Extensive testing of the...
Show moreA method of on-line monitoring AUV onboard systems is described. This algorithm determines deviations from normal operating conditions based on a damage level calculated from recursive least squares system identification performed on the system under consideration, followed by a gradient detection technique which extracts significant changes in identified model parameters System damage types are characterized together with likely system responses to such failures. Extensive testing of the algorithm is performed using several simulated AUV on-board systems undergoing different types of failures while carrying out different mission scenarios.
Show less - Date Issued
- 1993
- PURL
- http://purl.flvc.org/fcla/dt/12331
- Subject Headings
- Submersibles--Automatic control, Fault-tolerant computing, Algorithms--Data procedssing
- Format
- Document (PDF)
- Title
- Distributed processing tools for autonomous underwater vehicles.
- Creator
- Jade, Prashanth., Florida Atlantic University, Ganesan, Krishnamurthy
- Abstract/Description
-
Software for Autonomous Underwater Vehicles (AUVs) is usually complex. It involves several complicated tasks such as controller, path planner, map builder, and sensor processor. Distributed processing is unavoidable for such a complex software system with real-time response requirements. Once these processes are distributed over several computers, it is essential that they have some mechanism to communicate to each other to share information. Each process might communicate with several of the...
Show moreSoftware for Autonomous Underwater Vehicles (AUVs) is usually complex. It involves several complicated tasks such as controller, path planner, map builder, and sensor processor. Distributed processing is unavoidable for such a complex software system with real-time response requirements. Once these processes are distributed over several computers, it is essential that they have some mechanism to communicate to each other to share information. Each process might communicate with several of the other processes. Interprocess communication becomes an important issue. This thesis discusses the design and implementation of a generic distributed toolkit that facilitates the development of distributed software for AUVs. This toolkit makes the details ofinterprocess communication transparent to the programmers involved in the AUV software development. The toolkit provides efficient direct communication between processes and does not impose any constraints on the architecture of the distributed software. Conventional techniques for monitoring/debugging of sequential programs are not applicable for distributed processes. This is because the correctness of a real-time distributed program is determined not only by its "logical" correctness but also its "timing" correctness. Monitoring mainly comprises of observation of the system during its operation. Debugging is mostly a graphical "post-mortem" analyses of the dumps generated by the distributed program. This thesis also presents the design of a window based generic graphical monitoring/ debugging tool.
Show less - Date Issued
- 1992
- PURL
- http://purl.flvc.org/fcla/dt/14871
- Subject Headings
- Submersibles, Electronic data processing--Distributed processing, Real-Time data processing, Debugging in computer science
- Format
- Document (PDF)
- Title
- Digital signal processing for a high-resolution three-dimensional sonar imaging system for autonomous underwater vehicles.
- Creator
- Cao, Ping., Florida Atlantic University, Cuschieri, Joseph M., Sudhakar, Raghavan, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
In this dissertation, the digital signal processing techniques required for a 3-D sonar imaging system are examined. The achievable performance of the generated images is investigated by using a combination of theoretical analysis, computer simulation and field experiments. The system consists of a forward looking sonar, with separate projector and receiver. The projector is a line source with an 80 degrees by 1.2 degree beam pattern, which is electronically scanned within a 150 degree sector...
Show moreIn this dissertation, the digital signal processing techniques required for a 3-D sonar imaging system are examined. The achievable performance of the generated images is investigated by using a combination of theoretical analysis, computer simulation and field experiments. The system consists of a forward looking sonar, with separate projector and receiver. The projector is a line source with an 80 degrees by 1.2 degree beam pattern, which is electronically scanned within a 150 degree sector. The receiver is a multi element line array, where each transducer element has a directivity pattern that covers the full sector of view, that is 150 degrees by 80 degrees. The purpose of this sonar system is to produce three dimensional (3-D) images which display the underwater topography within the sector of view up to a range of 200 meters. The principle of operation of the proposed 3-D imaging system differs from other commonly used systems in that it is not based on the intensity of backscatter. The geometries of the targets are obtained from the delay and direction information that can be extracted from the signal backscatter. The acquired data is further processed using an approach based on sequential Fourier transforms to build the 3-D images. With careful selection of the system parameters, the generated images have sufficient quality to be used for AUV tasks such as obstacle avoidance, navigation and object classification. An approach based on a sophisticated two dimensional (2-D) autoregressive (AR) model is explored to further improve the resolution and generate images with higher quality. The real time processing requirements for image generation are evaluated, with the use of dedicated Digital Signal Processing (DSP) chips. A pipeline processing model is analyzed and developed on a selected system.
Show less - Date Issued
- 1992
- PURL
- http://purl.flvc.org/fcla/dt/12317
- Subject Headings
- Sonar, Signal processing--Digital techniques, Three-dimensional display systems, Submersibles
- Format
- Document (PDF)
- Title
- Development of Internet-based data management and retrieval schemes for AUV applications.
- Creator
- Bayard, Gildas Yann., Florida Atlantic University, An, Edgar
- Abstract/Description
-
The rapid increase in the amount of data gathered by Autonomous Underwater Vehicles (AUV) leads to a global data management issue. Indeed, this large data collection effort is only interesting if the data collected can be easily retrieved and analyzed by many researchers. The main contribution of this thesis is the design of data management and retrieval schemes useful to the whole AUV community that both simplify the access and treatment of the data collected. This is achieved by the use of...
Show moreThe rapid increase in the amount of data gathered by Autonomous Underwater Vehicles (AUV) leads to a global data management issue. Indeed, this large data collection effort is only interesting if the data collected can be easily retrieved and analyzed by many researchers. The main contribution of this thesis is the design of data management and retrieval schemes useful to the whole AUV community that both simplify the access and treatment of the data collected. This is achieved by the use of a self-describing standard data format (Hierarchical Data Format) and the use of Internet browsers' file download ability. Recent developments in Sun's Java applet technology have been used to provide a user-friendly Graphical User Interface (GUI) so that the user can select data files according to a large number of parameters (what variables have been collected, when and where).
Show less - Date Issued
- 1999
- PURL
- http://purl.flvc.org/fcla/dt/15687
- Subject Headings
- Submersibles--Data processing, Java (Computer program language), Application software--Development
- Format
- Document (PDF)
- Title
- Modular application server design for AUV data network access and distributed processing.
- Creator
- Delarue, Alexandre G., Florida Atlantic University, Smith, Samuel M.
- Abstract/Description
-
Autonomous Underwater Vehicles (AUV) collect a large volume of scientific data in every mission, using the onboard sensors, and store them in log files. The accessibility of these data is limited. Specific tools are required to extract the data to be processed on the user workstation with the installed analysis tools and scripts. The objective is to standardize and simplify the way data can be retrieved and processed from anywhere by anybody. The design of a server that manages the access to...
Show moreAutonomous Underwater Vehicles (AUV) collect a large volume of scientific data in every mission, using the onboard sensors, and store them in log files. The accessibility of these data is limited. Specific tools are required to extract the data to be processed on the user workstation with the installed analysis tools and scripts. The objective is to standardize and simplify the way data can be retrieved and processed from anywhere by anybody. The design of a server that manages the access to the data and to the applications that process them has been considered. Everything can then be done through the use of a single Java client executed on any Java compliant computer. Analysis tools are downloaded on the fly when needed and do not require any installation. New tools can be integrated into the application server in the form of plugins developed with an appropriate Java Library.
Show less - Date Issued
- 2000
- PURL
- http://purl.flvc.org/fcla/dt/12676
- Subject Headings
- Submersibles--Data processing, Java (Computer program language), Client/server computing
- Format
- Document (PDF)
- Title
- Performance and limitations of acoustic positioning using a tetrahedral ultra-short baseline array and an acoustic modem source transmitting frequency-hopped sequences.
- Creator
- Mohamed, Asif I., Florida Atlantic University, Beaujean, Pierre-Philippe, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The operation of unmanned underwater vehicles requires communications with other nearby vehicles as well as accurate positioning to prevent duplication of work, collisions and other mishaps. This thesis details the integration of an ultra-short baseline positioning system with four transducers arranged as a tetrahedron for use with the FAU Dual Purpose Acoustic Modem. The source position is estimated by processing coherently a series of frequency-hopped pulses to obtain a set of bearings,...
Show moreThe operation of unmanned underwater vehicles requires communications with other nearby vehicles as well as accurate positioning to prevent duplication of work, collisions and other mishaps. This thesis details the integration of an ultra-short baseline positioning system with four transducers arranged as a tetrahedron for use with the FAU Dual Purpose Acoustic Modem. The source position is estimated by processing coherently a series of frequency-hopped pulses to obtain a set of bearings, optimally combined through maximum likelihood estimation of the azimuth and elevation. A simulation has been implemented and experiments have been performed in a calibration tank. Model and experiments confirm that the accuracy of this system improves with the number of pulses and the signal-to-noise ratio. A mean positional error of 5.51% can be obtained with an SNR of 20 dB and a single processed pulse, the error decreases to 2.84% using six processed pulses.
Show less - Date Issued
- 2006
- PURL
- http://purl.flvc.org/fcla/dt/13412
- Subject Headings
- Underwater navigation, Remote submersibles, Computer integrated manufacturing systems, Acoustical engineering, Underwater acoustics--Instruments
- Format
- Document (PDF)
- Title
- A graphical Windows(c)-based cable and underwater system simulation software.
- Creator
- de Baudreuil, Jean., Florida Atlantic University, Driscoll, Frederick R.
- Abstract/Description
-
Underwater systems behavior prediction has become an important success factor in the design and implementation of marine systems. Most marine systems involve cables for mooring, deployment, recovery, or towing; however, estimating the response of these systems is difficult because of their non-linear behavior. Thus, numerical models are used to simulate submerged cabled systems. At FAU, many mission specific cable simulations have been developed, but no single, all encompassing software...
Show moreUnderwater systems behavior prediction has become an important success factor in the design and implementation of marine systems. Most marine systems involve cables for mooring, deployment, recovery, or towing; however, estimating the response of these systems is difficult because of their non-linear behavior. Thus, numerical models are used to simulate submerged cabled systems. At FAU, many mission specific cable simulations have been developed, but no single, all encompassing software package exists. This thesis develops a Windows(c) based software package to quickly and easily create FEA models of underwater cabled systems and simulate their response. The model is based on a discrete finite element analysis using linear elements. The software provides fully integrated and interactive Graphical User Interfaces with a 3-dimensional graphical display of the model, and integrates adapted data analysis and visualization tools. The software provides an easy and efficient way to simulate an underwater system involving cables.
Show less - Date Issued
- 2005
- PURL
- http://purl.flvc.org/fcla/dt/13232
- Subject Headings
- Oceanographic submersibles--Computer simulation, Computer software--Development, Simulation methods, Cables, Submarine
- Format
- Document (PDF)
- Title
- Software development of a hardware-in-the-loop simulation and a three-dimensional viewer for autonomous underwater vehicles.
- Creator
- Mahieu, Frederi., Florida Atlantic University, An, Edgar, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
This thesis describes the development of the hardware-in-the-loop simulation for FAU Autonomous Underwater Vehicles. The development was based on the existing simulation platform. For more efficiency and flexibility, this simulation package was ported to Linux. The hardware-in-the-loop simulation enables developers to connect the vehicle directly to a remote simulator. This kind of simulation is used to test the actual software components embedded in the vehicle system. The simulation package...
Show moreThis thesis describes the development of the hardware-in-the-loop simulation for FAU Autonomous Underwater Vehicles. The development was based on the existing simulation platform. For more efficiency and flexibility, this simulation package was ported to Linux. The hardware-in-the-loop simulation enables developers to connect the vehicle directly to a remote simulator. This kind of simulation is used to test the actual software components embedded in the vehicle system. The simulation package was enhanced by the addition of a 3D viewer. This thesis describes the whole development process, from feasibility study and implementation to qualification phases. This viewer is platform independent and designed to be connected to the simulator. It renders the AUV moving in a virtual environment. This tool can be used during all development steps, from tuning phases to post-mission analysis.
Show less - Date Issued
- 2000
- PURL
- http://purl.flvc.org/fcla/dt/15778
- Subject Headings
- Oceanographic submersibles--Computer simulation, Computer software--Development, Simulation methods, Three-dimensional display systems
- Format
- Document (PDF)
- Title
- Communications for a tethered underwater submersible.
- Creator
- Vulih, S., Clayton, David L., Harbor Branch Oceanographic Institute
- Date Issued
- 1980
- PURL
- http://purl.flvc.org/FCLA/DT/3183665
- Subject Headings
- Remote submersibles, Radio --Transmitters and transmission, Electric filters, Automatic control, Radio frequency modulation, Signal theory (Telecommunication), Sonar
- Format
- Document (PDF)
- Title
- Observations from research submersibles of megafaunal distribution on the continental margin off central eastern Florida.
- Creator
- Avent, R. M., Stanton, F. G.
- Date Issued
- 1979-06-26
- PURL
- http://purl.flvc.org/fcla/dt/3358625
- Subject Headings
- Johnson-Sea-Link II (Submarine), Submersibles, Continental shelf--Florida, Hydrographic surveying, Continental margins--Florida
- Format
- Document (PDF)
- Title
- Dynamics and Control of Autonomous Underwater Vehicles with Internal Actuators.
- Creator
- Li, Bo, Su, Tsung-Chow, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
This dissertation concerns the dynamics and control of an autonomous underwater vehicle (AUV) which uses internal actuators to stabilize its horizontalplane motion. The demand for high-performance AUVs are growing in the field of ocean engineering due to increasing activities in ocean exploration and research. New generations of AUVs are expected to operate in harsh and complex ocean environments. We propose a hybrid design of an underwater vehicle which uses internal actuators instead of...
Show moreThis dissertation concerns the dynamics and control of an autonomous underwater vehicle (AUV) which uses internal actuators to stabilize its horizontalplane motion. The demand for high-performance AUVs are growing in the field of ocean engineering due to increasing activities in ocean exploration and research. New generations of AUVs are expected to operate in harsh and complex ocean environments. We propose a hybrid design of an underwater vehicle which uses internal actuators instead of control surfaces to steer. When operating at low speeds or in relatively strong ocean currents, the performances of control surfaces will degrade. Internal actuators work independent of the relative ows, thus improving the maneuvering performance of the vehicle. We develop the mathematical model which describes the motion of an underwater vehicle in ocean currents from first principles. The equations of motion of a body-fluid dynamical system in an ideal fluid are derived using both Newton-Euler and Lagrangian formulations. The viscous effects of a real fluid are considered separately. We use a REMUS 100 AUV as the research model, and conduct CFD simulations to compute the viscous hydrodynamic coe cients with ANSYS Fluent. The simulation results show that the horizontal-plane motion of the vehicle is inherently unstable. The yaw moment exerted by the relative flow is destabilizing. The open-loop stabilities of the horizontal-plane motion of the vehicle in both ideal and real fluid are analyzed. In particular, the effects of a roll torque and a moving mass on the horizontal-plane motion are studied. The results illustrate that both the position and number of equilibrium points of the dynamical system are prone to the magnitude of the roll torque and the lateral position of the moving mass. We propose the design of using an internal moving mass to stabilize the horizontal-plane motion of the REMUS 100 AUV. A linear quadratic regulator (LQR) is designed to take advantage of both the linear momentum and lateral position of the internal moving mass to stabilize the heading angle of the vehicle. Alternatively, we introduce a tunnel thruster to the design, and use backstepping and Lyapunov redesign techniques to derive a nonlinear feedback control law to achieve autopilot. The coupling e ects between the closed-loop horizontal-plane and vertical-plane motions are also analyzed.
Show less - Date Issued
- 2016
- PURL
- http://purl.flvc.org/fau/fd/FA00004738, http://purl.flvc.org/fau/fd/FA00004738
- Subject Headings
- Dynamics., Remote submersibles--Design and construction., Ocean engineering., Fluid dynamics., Nonlinear control theory., Differentiable dynamical systems.
- Format
- Document (PDF)
- Title
- Development of an intelligent fuzzy obstacle avoidance system using SONAR modeling and simulation.
- Creator
- Bouxsein, Philip A., Florida Atlantic University, An, Edgar
- Abstract/Description
-
Response time to a threat or incident for coastline security is an area needing improvement. Currently, the U.S. Coast Guard is tasked with monitoring and responding to threats in coastal and port environments using boats or planes, and SCUBA divers. This can significantly hinder the response time to an incident. A solution to this problem is to use autonomous underwater vehicles (AUVs) to continuously monitor a port. The AUV must be able to navigate the environment without colliding into...
Show moreResponse time to a threat or incident for coastline security is an area needing improvement. Currently, the U.S. Coast Guard is tasked with monitoring and responding to threats in coastal and port environments using boats or planes, and SCUBA divers. This can significantly hinder the response time to an incident. A solution to this problem is to use autonomous underwater vehicles (AUVs) to continuously monitor a port. The AUV must be able to navigate the environment without colliding into objects for it to operate effectively. Therefore, an obstacle avoidance system (OAS) is essential to the activity of the AUV. This thesis describes a systematic approach to characterize the OAS performance in terms of environments, obstacles, SONAR configuration and signal processing methods via modeling and simulation. A fuzzy logic based OAS is created using the simulation. Subsequent testing of the OAS demonstrates its effectiveness in unknown environments.
Show less - Date Issued
- 2006
- PURL
- http://purl.flvc.org/fcla/dt/13390
- Subject Headings
- Fuzzy logic, Submersibles--Automatic control, Neural networks (Computer science), Underwater acoustics--Computer simulation, Sonar--Computer simulation
- Format
- Document (PDF)
- Title
- Optical Characterization ofPort Everglades Focusing on Underwater Visibility.
- Creator
- Whipple, Dustin E., Frisk, George V., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The development of an unmanned underwater vehicle at Florida Atlantic University with onboard optical sensors has prompted the temporal and spatial optical characterization of Port Everglades, with in-situ measurements of the turbidity, conductivity, and temperature. Water samples were collected for laboratory analysis where attenuation and absorption were measured with a bench top spectrometer. All of the measurements showed a high degree of variability within the port on a temporal and...
Show moreThe development of an unmanned underwater vehicle at Florida Atlantic University with onboard optical sensors has prompted the temporal and spatial optical characterization of Port Everglades, with in-situ measurements of the turbidity, conductivity, and temperature. Water samples were collected for laboratory analysis where attenuation and absorption were measured with a bench top spectrometer. All of the measurements showed a high degree of variability within the port on a temporal and spatial basis. Correlations were researched between the measured properties as well as tide and current. Temporal variations showed a high correlation to tidal height but no relation was found between turbidity and current, or salinity. Spatial variations were primarily determined by proximity to the port inlet. Proportionality constants were discovered to relate turbidity to scattering and absorption coefficients. These constants along with future turbidity measurements will allow the optimization of any underwater camera system working within these waters.
Show less - Date Issued
- 2007
- PURL
- http://purl.flvc.org/fau/fd/FA00012569
- Subject Headings
- Oceanographic submersibles--Mathematical models, Image processing--Digital techniques, Optical pattern recognition, Port Everglades (Fort Lauderdale, Fla)
- Format
- Document (PDF)
- Title
- Variability of cold-water coral mounds in a high sediment input and tidal current regime, Straits ofFlorida.
- Creator
- Correa, T.B.S., Grasmueck, M., Eberli, G.P., Reed, John K., Verwer, K., Purkis, S.
- Date Issued
- 2012
- PURL
- http://purl.flvc.org/fau/fd/FA00007166
- Subject Headings
- Florida, Straits of, Cold-water corals, Deep sea corals, Submersibles--Automatic control, Underwater vehicles, Great Bahama Bank (Bahamas), Morphology
- Format
- Document (PDF)
- Title
- Development of a morphing autonomous underwater vehicle for path and station keeping in complex current environments.
- Creator
- Meneses, Andrea M., Su, Tsung-Chow, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
This thesis explores the feasibility of using morphing rudders in autonomous underwater vehicles (AUVs) to improve their performance in complex current environments. The modeling vehicle in this work corresponds to the Florida Atlantic University's Ocean EXplorer (OEX) AUV. The AUV nonlinear dynamic model is limited to the horizontal plane and includes the effect of ocean current. The main contribution of this thesis is the use of active rudders to successfully achieve path keeping and...
Show moreThis thesis explores the feasibility of using morphing rudders in autonomous underwater vehicles (AUVs) to improve their performance in complex current environments. The modeling vehicle in this work corresponds to the Florida Atlantic University's Ocean EXplorer (OEX) AUV. The AUV nonlinear dynamic model is limited to the horizontal plane and includes the effect of ocean current. The main contribution of this thesis is the use of active rudders to successfully achieve path keeping and station keeping of an AUV under the influence of unsteady current force. A constant ocean current superimposed with a sinusoidal component is considered. The vehicle's response is analyzed for a range of current frequencies.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00004137, http://purl.flvc.org/fau/fd/FA00004137
- Subject Headings
- Autonomous robots -- Design and construction, Fracture mechanics, Manipulation (Mechanism) -- Control, Remote submersibles -- Design and construction, Vehicles, Remotely piloted -- Design and construction
- Format
- Document (PDF)
- Title
- Design and Deployment Analysis of Morphing Ocean Structure.
- Creator
- Li, Yanjun, Su, Tsung-Chow, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
As humans explore greater depths of Earth’s oceans, there is a growing need for the installation of subsea structures. 71% of the earth’s surface is ocean but there are limitations inherent in current detection instruments for marine applications leading to the need for the development of underwater platforms that allow research of deeper subsea areas. Several underwater platforms including Autonomous Underwater Vehicles (AUVs), Remote Operated Vehicles (ROVs), and wave gliders enable more...
Show moreAs humans explore greater depths of Earth’s oceans, there is a growing need for the installation of subsea structures. 71% of the earth’s surface is ocean but there are limitations inherent in current detection instruments for marine applications leading to the need for the development of underwater platforms that allow research of deeper subsea areas. Several underwater platforms including Autonomous Underwater Vehicles (AUVs), Remote Operated Vehicles (ROVs), and wave gliders enable more efficient deployment of marine structures. Deployable structures are able to be compacted and transported via AUV to their destination then morph into their final form upon arrival. They are a lightweight, compact solution. The wrapped package includes the deployable structure, underwater pump, and other necessary instruments, and the entire package is able to meet the payload capability requirements. Upon inflation, these structures can morph into final shapes that are a hundred times larger than their original volume, which extends the detection range and also provides long-term observation capabilities. This dissertation reviews underwater platforms, underwater acoustics, imaging sensors, and inflatable structure applications then proposes potential applications for the inflatable structures. Based on the proposed applications, a conceptual design of an underwater tubular structure is developed and initial prototypes are built for the study of the mechanics of inflatable tubes. Numerical approaches for the inflation process and bending loading are developed to predict the inflatable tubular behavior during the structure’s morphing process and under different loading conditions. The material properties are defined based on tensile tests. The numerical results are compared with and verified by experimental data. The methods used in this research provide a solution for underwater inflatable structure design and analysis. Several ocean morphing structures are proposed based on the inflatable tube analysis.
Show less - Date Issued
- 2016
- PURL
- http://purl.flvc.org/fau/fd/FA00004752, http://purl.flvc.org/fau/fd/FA00004752
- Subject Headings
- Air-supported structures--Design and construction., Remote submersibles--Design and construction., Tensile architecture., Fluid mechanics., Structural dynamics., Ocean engineering., Adaptive control systems.
- Format
- Document (PDF)
- Title
- Simulator and location-aware routing protocol for mobile ad hoc acoustic networks of AUVs.
- Creator
- Carlson, Edward A., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Acoustic networks of autonomous underwater vehicles (AUVs) show great promise, but a lack of simulation tools and reliance on protocols originally developed for terrestrial radio networks has hindered progress. This work addresses both issues. A new simulator of underwater communication among AUVs provides accurate communication modeling and flexible vehicle behavior, while a new routing protocol, location-aware source routing (LASR) provides superior network performance. The new simulator...
Show moreAcoustic networks of autonomous underwater vehicles (AUVs) show great promise, but a lack of simulation tools and reliance on protocols originally developed for terrestrial radio networks has hindered progress. This work addresses both issues. A new simulator of underwater communication among AUVs provides accurate communication modeling and flexible vehicle behavior, while a new routing protocol, location-aware source routing (LASR) provides superior network performance. The new simulator was used to evaluate communication without networking, and then with networking using the coding or dynamic source routing (DSR) protocols. The results confirmed that a network was essential to ensure effective fleet-wide communication. The flooding protocol provided extremely reliable communication but with low message volumes. The DSR protocol, a popular routing protocol due to its effectiveness in terrestrial radio networks, proved to be a bad choice in an acoustic environment: in most cases, it suffered from both poor reliability and low message volumes. Due to the high acoustic latency, even moderate vehicle speeds caused the network topology to change faster than DSR could adapt. DSR's reliance on shortest-path routing also proved to be a significant disadvantage. Several DSR optimizations were also tested; most proved to be unhelpful or actually harmful in an underwater acoustic network. LASR was developed to address the problems noted in flooding and DSR. LASR was loosely derived from DSR, most significantly retaining source routes and the reply/request route discovery technique. However, LASR added features which proved, in simulation, to be significant advantages -- two of the most effective were a link/route metric and a node tracking system. To replace shortest-path routing, LASR used the expected transmission count (ETX) metric., This allowed LASR to make more informed routing decisions which greatly increased performance compared to DSR. The node tracking system was the most novel addition: using only implicit communication coupled with the use of time-division multiple access (TDMA), the tracking system provided predicted node locations. These predictions made it possible for LASR to proactively respond to topology changes. In most cases, LASR outperformed flooding and DSR in message delivery reliability and message delivery volume.
Show less - Date Issued
- 2009
- PURL
- http://purl.flvc.org/FAU/187208
- Subject Headings
- Ad hoc networks (Computer networks), Computer network protocols, Routers (Computer networks), Mobile communication systems, Design and construction, Remote submersibles, Design and construction
- Format
- Document (PDF)
- Title
- Task allocation and path planning for acoustic networks of AUVs.
- Creator
- Deng, Yueyue, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
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Controlling the cooperative behaviors of a fleet of autonomous underwater vehicles in a stochastic, complex environment is a formidable challenge in artificial intelligence. The complexity arises from the challenges of limited navigation and communication capabilities of underwater environment. A time critical cooperative operation by acoustic networks of Multiple Cooperative Vehicles (MCVs) necessitates a robust task allocation mechanism and an efficient path planning model. In this work, we...
Show moreControlling the cooperative behaviors of a fleet of autonomous underwater vehicles in a stochastic, complex environment is a formidable challenge in artificial intelligence. The complexity arises from the challenges of limited navigation and communication capabilities of underwater environment. A time critical cooperative operation by acoustic networks of Multiple Cooperative Vehicles (MCVs) necessitates a robust task allocation mechanism and an efficient path planning model. In this work, we present solutions to investigate two aspects of the cooperative schema for multiple underwater vehicles under realistic underwater acoustic communications: a Location-aided Task Allocation Framework (LAAF) algorithm for multi-target task assignment and a mathematical programming model, the Grid-based Multi-Objective Optimal Programming (GMOOP), for finding an optimal vehicle command decision given a set of objectives and constraints. We demonstrate that, the location-aided auction strategies perform significantly better than the generic auction algorithm in terms of effective task allocation time and information bandwidth requirements. In a typical task assignment scenario, the time needed in the LAAF algorithm is only a fraction compared to the generic auction algorithm. On the other hand; the GMOOP path planning technique provides a unique means for multi-objective tasks by cooperative agents with limited communication capabilities. Under different environmental settings, the GMOOP path planning technique is proved to provide a method with balance of sufficient expressive power and flexibility, and its solution algorithms tractable in terms of mission completion time, with a limited increase of overhead in acoustic communication. Prior to this work, existing multi-objective action selection methods were limited to robust networks where constant communication available., The dynamic task allocation, together with the GMOOP path planning controller, provides a comprehensive solution to the search-classify tasks for cooperative AUVs.
Show less - Date Issued
- 2010
- PURL
- http://purl.flvc.org/FAU/1927865
- Subject Headings
- Computer network protocols, Routers (Computer networks), Remote submersibles, Design and construction, Mobile communication systems, Design and construction, Ad hoc networks (Computer networks)
- Format
- Document (PDF)