The Experts below are selected from a list of 10701 Experts worldwide ranked by ideXlab platform
Fumin Zhang - One of the best experts on this subject based on the ideXlab platform.
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spiraling motion of underwater Gliders modeling analysis and experimental results
Ocean Engineering, 2013Co-Authors: Shaowei Zhang, Aiqun Zhang, Fumin ZhangAbstract:This paper presents a thorough approach characterizing the spiraling motion of underwater Gliders. The dynamic model for underwater Gliders, steered by a single internal movable and rotatable mass, is established. Spiraling motions are equilibria of the dynamics, for which equations are derived and then solved by a recursive algorithm with fast convergence. This theoretical method is applied to the Seawing underwater Glider whose hydrodynamic coefficients are computed using computational fluid dynamics (CFD) software packages. In a recent experiment in the South China Sea, the Seawing Glider produced a spiraling motion against strong ocean current, agreeing with theoretical predictions. Hence the recursive algorithm may be used to compute control input to achieve desired spiraling motion for underwater Gliders in practice.
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motion parameter optimization and sensor scheduling for the sea wing underwater Glider
IEEE Journal of Oceanic Engineering, 2013Co-Authors: Fumin Zhang, Aiqun Zhang, Wenming Jin, Yu TianAbstract:Underwater Gliders adjust buoyancy to generate gliding motion through water columns using a pair of wings. Various types of underwater Gliders have been developed and have been tested as efficient long-distance, long-duration ocean sampling platforms. We introduce the Chinese Sea-Wing underwater Glider and develop methods to increase its gliding range by optimizing the steady motion parameters to save energy. The methods are based on a model that relates gliding range to steady gliding motion parameters as well as energy consumption. A sensor scheduling strategy accounts for the distributed features of vertical profiles so that the sampling resolution is adjusted to reduce energy consumption of sensing. The effect of the proposed methods to increase gliding range is evaluated on the Sea-Wing Glider. The proposed methods may be applicable to other types of underwater Gliders.
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peer reviewed technical communication motion parameter optimization and sensor scheduling for the sea wing underwater Glider
2013Co-Authors: Fumin Zhang, Aiqun Zhang, Wenming Jin, Yu TianAbstract:Underwater Gliders adjust buoyancy to generate gliding motion through water columns using a pair of wings. Various types of underwater Gliders have been developed and have been tested as efficient long-distance, long-duration ocean sampling platforms. We introduce the Chinese Sea-Wing under- water Glider and develop methods to increase its gliding range by optimizing the steady motion parameters to save energy. The methods are based on a model that relates gliding range to steady gliding motion parameters as well as energy consumption. A sensor scheduling strategy accounts for the distributed features of vertical profiles so that the sampling resolution is adjusted to reduce energy consumption of sensing. The effect of the proposed methods to increase gliding range is evaluated on the Sea-Wing Glider. The proposed methods may be applicable to other types of underwater Gliders.
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real time modelling of tidal current for navigating underwater Glider sensing networks
Procedia Computer Science, 2012Co-Authors: Xiaolin Liang, Dongsik Chang, Fumin ZhangAbstract:Ocean models that are able to provide accurate and real-time prediction of ocean currents will improve the performance of Glider navigation. In this paper, we propose a novel approach to compute a model for ocean currents at higher resolution than existing approaches. By focusing on a small area and incorporating measurements from multiple Gliders, we are able to perform real-time computation of the model, which can be used to improve performance of underwater Glider navigation in the ocean. Our model uses a lower resolution, larger scale dataset generated from existing models to initialize the computation. We have also demonstrated incorporating data streams from high frequency (HF) radar measurements of surface currents. Glider navigation performance using the proposed ocean currents model is demonstrated in a simulated flow field based on data collected off the coast of Georgia, USA.
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cooperative control for ocean sampling the Glider coordinated control system
IEEE Transactions on Control Systems and Technology, 2008Co-Authors: Derek A Paley, Fumin Zhang, Naomi Ehrich LeonardAbstract:The Glider coordinated control system (GCCS) uses a detailed Glider model for prediction and a simple particle model for planning to steer a fleet of underwater Gliders to a set of coordinated trajectories. The GCCS also serves as a simulation testbed for the design and evaluation of multivehicle control laws. In this brief, we describe the GCCS and present experimental results for a virtual deployment in Monterey Bay, CA and a real deployment in Buzzards Bay, MA.
G Griffiths - One of the best experts on this subject based on the ideXlab platform.
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underwater Glider reliability and implications for survey design
Journal of Atmospheric and Oceanic Technology, 2014Co-Authors: Mario P Brito, D A Smeed, G GriffithsAbstract:It has been 20 years since the concept of Autonomous Oceanographic Sampling Network (AOSN) was first introduced. This vision has been brought closer to reality with the introduction of undersea Gliders. Whilst in terms of functionality the undersea Glider has shown to be capable of meeting the AOSN vision, in terms of reliability there is no community-wide hard evidence on whether persistent presence is currently being achieved. This paper studies the reliability of undersea Gliders in order to assess the feasibility of using these platforms for future AOSN. The data used is taken from 205 deployments of Gliders by 12 European laboratories between 2008 and 2012. Risk profiles were calculated for two makes of deep underwater Glider; there is no statistically significant difference between them. Regardless of make the probability of a deep undersea Glider surviving a 90 day mission without pre-mature mission end is approximately 0.5. The probability of a shallow undersea Glider surviving 30 day mission without premature mission end is 0.59. This implies that to date factors other than the energy available are preventing undersea Gliders achieving their maximum capability. This reliability information was used to quantify the likelihood of two reported undersea Glider surveys meeting the observation needs for a period of 6 months and to quantify the level of redundancy needed to in order to increase the likelihood of meeting the observation needs.
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an assessment of the use of ocean Gliders to undertake acoustic measurements of zooplankton the distribution and density of antarctic krill euphausia superba in the weddell sea
Limnology and Oceanography-methods, 2014Co-Authors: Damien Guihen, Sophie Fielding, Eugene J Murphy, Karen J Heywood, G GriffithsAbstract:A calibrated 120 kHz single-beam echo-sounder was integrated into an ocean Glider and deployed in the Weddell Sea, Southern Ocean. The Glider was deployed for two short periods in January 2012, in separate survey boxes on the continental shelf to the east of the Antarctic Peninsula, to assess the distribution of Antarctic krill (Euphausia superba). During the Glider missions, a research vessel undertook acoustic transects using a calibrated, hull-mounted, multi-frequency echo-sounder. Net hauls were taken to validate acoustic targets and parameterize acoustic models. Krill targets were identified using a thresholded schools analysis technique (SHAPES), and acoustic data were converted to krill density using the stochastic distorted-wave Born approximation (SDWBA) target strength model. A sensitivity analysis of Glider pitch and roll indicated that, if not taken into account, Glider orientation can impact density estimates by up to 8-fold. Glider-based, echo-sounder–derived krill density profiles for the two survey boxes showed features coherent with ship-borne measurements, with peak densities in both boxes around a depth of 60 m. Monte Carlo simulation of Glider subsampling of ship-borne data showed no significant difference from observed profiles. Simulated Glider dives required at least an order of magnitude more time than the ship to similarly estimate the abundance of krill within the sample regions. These analyses highlight the need for suitable sampling strategies for Glider-based observations and are our first steps toward using autonomous underwater vehicles for ecosystem assessment and long-term monitoring. With appropriate survey design, Gliders can be used for estimating krill distribution and abundance.
Naomi Ehrich Leonard - One of the best experts on this subject based on the ideXlab platform.
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cooperative control for ocean sampling the Glider coordinated control system
IEEE Transactions on Control Systems and Technology, 2008Co-Authors: Derek A Paley, Fumin Zhang, Naomi Ehrich LeonardAbstract:The Glider coordinated control system (GCCS) uses a detailed Glider model for prediction and a simple particle model for planning to steer a fleet of underwater Gliders to a set of coordinated trajectories. The GCCS also serves as a simulation testbed for the design and evaluation of multivehicle control laws. In this brief, we describe the GCCS and present experimental results for a virtual deployment in Monterey Bay, CA and a real deployment in Buzzards Bay, MA.
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underwater Glider system study
Scripps Institution of Oceanography, 2003Co-Authors: Scott A Jenkins, Naomi Ehrich Leonard, Douglas E Humphreys, Jeff Sherman, Jim Osse, Clayton Jones, J Graver, Ralf Bachmayer, Ted Clem, Paul J CarrollAbstract:The goals of this study are to determine how to advance from present capabilities of underwater Glider (and hybrid motorGlider) technology to what could be possible within the next few years; and to identify critical research issues that must be resolved to make such advancements possible. These goals were pursued by merging archival flight data with numerical model results and system spreadsheet analysis to extrapolate from the present state-of-the–art in underwater (UW) Gliders to potential future technology levels. Using existing underwater Gliders (legacy Gliders) as calibration, this merger approach was applied to six basic Glider types that were conceived to satisfy the requirements of five functional classes. Functional classes were posed based on an evaluation of the attributes and limitations of underwater Gliders in the context of a broad range of potential Navy needs in the littoral and deep-water regimes. Those functional classes included: Depth- Unlimited Roaming; Depth-Limited Roaming; Virtual Station Keeping; Payload Delivery; Level-Flight Hybrids.
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underwater Glider dynamics and control
2002Co-Authors: Naomi Ehrich LeonardAbstract:Abstract : My long-term goal is to help improve versatility of underwater Gliders as individual or networked platforms for ocean sampling and other applications by contributing to the development of a methodology for designing and analyzing high-performance, cost-effective underwater Glider controllers.
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Model-based feedback control of autonomous underwater Gliders
IEEE Journal of Oceanic Engineering, 2001Co-Authors: Naomi Ehrich Leonard, Joshua G. GraverAbstract:We describe the development of feedback control for autonomous underwater Gliders. Feedback is introduced to make the Glider motion robust to disturbances and uncertainty. Our focus is on buoyancy-propelled, fixed-wing Gliders with attitude controlled by means of active internal mass redistribution. We derive a nonlinear dynamic model of a nominal Glider complete with hydrodynamic forces and coupling between the vehicle and the movable internal mass. We use this model to study stability and controllability of glide paths and to derive feedback control laws. For our analysis, we restrict to motion in the vertical plane and consider linear control laws. For illustration, we apply our methodology to a model of our own laboratory-scale underwater Glider
Xiaobo Tan - One of the best experts on this subject based on the ideXlab platform.
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miniature underwater Glider design and experimental results
IEEE-ASME Transactions on Mechatronics, 2014Co-Authors: Feitian Zhang, John Thon, Cody Thon, Xiaobo TanAbstract:The concept of gliding robotic fish combines gliding and fin-actuation mechanisms to realize energy-efficient locomotion and high maneuverability. Such robots hold strong promise for mobile sensing in versatile aquatic environments. In this paper, we present the design and implementation of a miniature Glider, a key enabling component for gliding robotic fish. The steady-state glide equation is first presented and then solved numerically for given net-buoyancy and movable mass displacement. Scaling analysis is conducted to understand the tradeoff between the glide performance and energy cost. Comprehensive design for the Glider is provided. Experimentation and modeling analysis are further conducted to investigate the impacts of movable mass displacement, net buoyancy, and wing size on the gliding performance.
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miniature underwater Glider design modeling and experimental results
International Conference on Robotics and Automation, 2012Co-Authors: Feitian Zhang, John Thon, Cody Thon, Xiaobo TanAbstract:The concept of gliding robotic fish combines gliding and fin-actuation mechanisms to realize energy-efficient locomotion and high maneuverability, and holds strong promise for mobile sensing in versatile aquatic environments. In this paper we present the modeling and design of a miniature fish-like Glider, a key enabling component for gliding robotic fish. The full dynamics of the Glider is first derived and then reduced to the sagittal plane, where the lift, drag, and pitch moment coefficients are obtained as linear or quadratic functions of the attack angle based on computational fluid dynamics (CFD) analysis. The model is used to design the Glider by accommodating stringent constraints on dimensions yet meeting the desired specification on speed. A fully untethered prototype of underwater Glider is developed, with a weight of 4 kg and length of 40 cm. With a net buoyancy of 20 g, it realizes a steady gliding speed of 20 cm/s. The volume and net buoyancy of this Glider are less than 10% and 5%, respectively, of those of reported Gliders in the literature, and its speed per unit net buoyancy is over 9 times of those other vehicles. Experimental results have shown that the model is able to capture well both the steady glide behavior under different control inputs, and the dynamics during transients.
Damien Guihen - One of the best experts on this subject based on the ideXlab platform.
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an assessment of the use of ocean Gliders to undertake acoustic measurements of zooplankton the distribution and density of antarctic krill euphausia superba in the weddell sea
Limnology and Oceanography-methods, 2014Co-Authors: Damien Guihen, Sophie Fielding, Eugene J Murphy, Karen J Heywood, G GriffithsAbstract:A calibrated 120 kHz single-beam echo-sounder was integrated into an ocean Glider and deployed in the Weddell Sea, Southern Ocean. The Glider was deployed for two short periods in January 2012, in separate survey boxes on the continental shelf to the east of the Antarctic Peninsula, to assess the distribution of Antarctic krill (Euphausia superba). During the Glider missions, a research vessel undertook acoustic transects using a calibrated, hull-mounted, multi-frequency echo-sounder. Net hauls were taken to validate acoustic targets and parameterize acoustic models. Krill targets were identified using a thresholded schools analysis technique (SHAPES), and acoustic data were converted to krill density using the stochastic distorted-wave Born approximation (SDWBA) target strength model. A sensitivity analysis of Glider pitch and roll indicated that, if not taken into account, Glider orientation can impact density estimates by up to 8-fold. Glider-based, echo-sounder–derived krill density profiles for the two survey boxes showed features coherent with ship-borne measurements, with peak densities in both boxes around a depth of 60 m. Monte Carlo simulation of Glider subsampling of ship-borne data showed no significant difference from observed profiles. Simulated Glider dives required at least an order of magnitude more time than the ship to similarly estimate the abundance of krill within the sample regions. These analyses highlight the need for suitable sampling strategies for Glider-based observations and are our first steps toward using autonomous underwater vehicles for ecosystem assessment and long-term monitoring. With appropriate survey design, Gliders can be used for estimating krill distribution and abundance.
