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Conference on Lasers and Electro-Optics (CLEO)

作者： Beckett Colson Anna P. M. Michel Woods Hole Oceanographic Institution Woods Hole MA USA Massachusetts Institute of Technology Cambridge MA USA MIT-WHOI Joint Program in Oceanography/Applied Ocean Science & Engineering Cambridge and Woods Hole MA USA

The measurement of dissolved carbon dioxide is important for understanding many ocean processes. Here we present the design and field deployment of a TDLAS sensor for the measurement of dissolved carbon dioxide.

ISBN: (纸本)9781943580910

关键词： Spectroscopy Semiconductor lasers Oceans Instruments Sea measurements Measurement by laser beam Carbon dioxide

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Adaptive multi-altitude search and sampling of sparsely distributed natural phenomena

Adaptive multi-altitude search and sampling of sparsely dist...

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IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

作者： Jessica E. Todd Seth McCammon Yogesh Girdhar Nicholas Roy Dana Yoerger Department of Aeronautics and Astronautics MIT-WHOI Joint Program in Applied Ocean Science and Engineering at the Woods Hole Oceanographic Institution (WHOI) Massachusetts Institute of Technology (MIT) Applied Ocean Physics and Engineering Department Woods Hole Oceanographic Institution Woods Hole MA USA Department of Aeronautics and Astronautics Massachusetts Institute of Technology

ISBN: (数字)9798350377705

ISBN: (纸本)9798350377712

In this paper, we propose a novel method for autonomously seeking out sparsely distributed targets in an unknown underwater environment. Our Sparse Adaptive Search and Sample (SASS) algorithm mixes low-altitude observations of discrete targets with high-altitude observations of the surrounding substrates. By using prior information about the distribution of targets across substrate types in combination with belief modelling over these substrates in the environment, high-altitude observations provide information that allows SASS to quickly guide the robot to areas with high target densities. A maximally informative path is autonomously constructed online using Monte Carlo Tree Search with a novel acquisition function to guide the search to maximise observations of unique targets. We demonstrate our approach in a set of simulated trials using a novel generative species model. SASS consistently outperforms the canonical boustrophedon planner by up to 36% in seeking out unique targets in the first 75-90% of time it takes for a boustrophedon survey. Additionally, we verify the performance of SASS on two real world coral reef datasets.

关键词： Surveys Adaptation models Monte Carlo methods Adaptive systems Marine vegetation Substrates Intelligent robots

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Corrigendum to “Non-linear singularity formation for circular vortex sheets”

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Quarterly of Applied Mathematics 2024年第2期82卷 449-450页

作者： Murray, Ryan Wilcox, Galen Department of Mathematics North Carolina State University Raleigh NC 27607 MIT-WHOI Joint Program in Oceanography/Applied Ocean Science & Engineering Cambridge MA 02139 and Woods Hole MA 02543

Abstract: This paper serves as a short corrigendum, describing an error in the derivation of the linearized equation. The main theorems remain correct, but they are based upon an incorrect linearization of the Birkhoff-Rott equation and hence are not directly applicable to the original physical problem.

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A Low-Cost Entangling Drifter for Sargassum Tracking: Design and Experimental Evaluation

A Low-Cost Entangling Drifter for Sargassum Tracking: Design...

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OCEANS

作者： Chase Pixa Kevin Manganini Alyson Myers Anna PM Michel MIT-WHOI Joint Program in Applied Ocean Science and Engineering Cambridge USA Applied Ocean Physics and Engineering Woods Hole Oceanographic Institution USA Fearless Fund Washington D.C. USA

Since 2011, Sargassum, a free-floating macroalgae, has been causing significant ecological and economic damage to coastal regions in the Northern Equatorial Atlantic due to its voluminous blooms. To better understand the fate and effects of Sargassum, approaches are needed to track its transport. Here we developed a low-cost drifter, designed to entangle with Sargassum, to aid in its tracking providing in situ movement data to ground-truth models and supplementing gaps in satellite imaging. The results of 27 drifter designs and five days of field trials are presented. The successful entanglement and tracking with the Sargassum demonstrated here can guide future studies to further our understanding of the movement of Sargassum in the great Atlantic Sargassum belt (GASB).

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Improved vehicle based multibeam bathymetry using sub-maps and SLAM

Improved vehicle based multibeam bathymetry using sub-maps a...

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2005 IEEE/RSJ International Conference on Intelligent Robots and Systems

作者： C. Roman H. Singh MIT/WHOI Joint Program in Applied Ocean Science and Engineering Massachusetts Institute of Technology Cambridge MA USA Department of Applied Ocean Physics and Engineering Woods Hole Oceanographic Institution Woods Hole MA USA

This paper presents an algorithm to improve sub-sea acoustic multibeam bottom mapping based on the simultaneous mapping and localization (SLAM) methodology. Multibeam bathymetry from underwater water vehicles can yield valuable large scale terrain maps of the sea door, but the overall accuracy of these maps is typically limited by the accuracy of the vehicle position estimates. The solution presented here uses small bathymetric patches created over short time scales in a sub-mapping context. These patches are registered with respect to one another and assembled in a single coordinate frame to produce a more accurate terrain estimate and provide improved renavigation of the vehicle trajectory. The mapping is implemented using a delayed state extended Kalman filter (EKF) and results are shown for a real world multibeam data set collected at the mid-Atlantic ridge using the JASON ROV.

关键词： Simultaneous localization and mapping Terrain mapping Marine vehicles Underwater vehicles Underwater acoustics Large-scale systems Yield estimation Assembly Delay Remotely operated vehicles

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Visually augmented navigation in an unstructured environment using a delayed state history

Visually augmented navigation in an unstructured environment...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： R. Eustice O. Pizarro H. Singh MIT/WHOI Joint Program in Applied Ocean Science and Engineering Massachusetts Institute of Technology Cambridge MA USA Department of Applied Ocean Physics and Engineering Woods Hole Oceanographic Institution Woods Hole MA USA

This work describes a framework for sensor fusion of navigation data with camera-based 5 DOF relative pose measurements for 6 DOF vehicle motion in an unstructured 3D underwater environment. The fundamental goal of this work is to concurrently estimate online current vehicle position and its past trajectory. This goal is framed within the context of improving mobile robot navigation to support sub-sea science and exploration. Vehicle trajectory is represented by a history of poses in an augmented state Kalman filter. Camera spatial constraints from overlapping imagery provide partial observation of these poses and are used to enforce consistency and provide a mechanism for loop-closure. The multi-sensor camera + navigation framework is shown to have compelling advantages over a camera-only based approach by: 1) improving the robustness of pairwise image registration, 2) setting the free gauge scale, and 3) allowing for a unconnected camera graph topology. Results are shown for a real world data set collected by an autonomous underwater vehicle in an unstructured undersea environment.

关键词： Navigation Delay History Cameras Underwater vehicles Robot vision systems Sensor fusion Motion measurement Mobile robots Robustness

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Micro-bathymetric mapping using acoustic range images

Micro-bathymetric mapping using acoustic range images

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OCEANS

This work focuses on the creation of high resolution micro-bathymetric maps using a high frequency pencil beam sonar. These maps typically cover areas of 10's to 100's of square meters. Data is collected using a sonar mounted to an underwater vehicle that can be positioned at discrete locations on the sea floor or flown in a survey pattern above the bottom. Specifically, we are focused on improving the accuracy of these terrain maps by merging sonar pings taken from multiple vantage points over the same location. This requires the adaption of data registration techniques to handle errors related to the sonar sensor. The registration can also be modified to incorporate the navigation data available from an instrumented underwater vehicle. A two axis scanning sonar was used to gather data in the form of densely sampled range images. The data registration works on the 3D projection of these range images in a scan-matching manner. Through this process regions occluded in a single scan are filled with data available from other scans and individual pings which show a poor return are removed. Refined estimates of the scan vantage points are also generated during the registration. The initial estimates of these locations are provided by navigation data. The practical application of this work complements photographic mapping when visibility is limited. It also provides additional measurements which can be used to improve vehicle navigation.

关键词： Sonar navigation Sonar measurements Remotely operated vehicles Underwater vehicles Sea floor Underwater acoustics Layout Oceans Acoustical engineering Acoustic beams

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Enabling Under-Ice Geochemical Observations with a Size, Weight, and Power-Constrained Robot

arXiv

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arXiv 2022年

作者： Horowitz, Jess Preston, Victoria Michel, Anna P.M. Mechanical Engineering Massachusetts Institute of Technology Cambridge United States MIT-WHOI Joint Program Massachussetts Institute of Technology Cambridge United States Applied Ocean Physics and Engineering Woods Hole Oceanographic Institution Woods Hole United States

Estimates of greenhouse gas emissions from Arctic estuarine environments are dominated by in situ summer-time ice-free dissolved gas measurements due to the logistical ease of performing field observations in these conditions. Recent evidence in coastal Arctic environments, however, has demonstrated that dissolved methane (CH4) and carbon dioxide (CO2) are strongly seasonally variable, and at least one significant gas ventilation event occurs during the spring freshet. Whether the Arctic serves as a source or sink of greenhouse emissions has significant implications on modeling climate change and its feedback mechanisms. To enable higher resolution spatiotemporal measurements of dissolved gases in typically undersampled conditions, remotely operated vehicles (ROVs) can be used to extract near continuous water samples below ice before and during the spring freshet. Here, we present a size, weight, and power-constrained (SWAP) underwater vehicle (UV) and novel geochemical sampling system suitable for taking under-ice geochemical observations and demonstrate the proposed system in a field-analog setting for Arctic estuarine studies. Copyright © 2022, The Authors. All rights reserved.

关键词： Carbon dioxide

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Exactly Sparse Delayed-State Filters

Exactly Sparse Delayed-State Filters

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IEEE International Conference on Robotics and Automation (ICRA)

作者： R.M. Eustice H. Singh J.J. Leonard MIT/WHOI Joint Program in Applied Ocean Science and Engineering Woods Hole Oceanographic Institution Woods Hole MA USA Department of Applied Ocean Physics and Engineering Woods Hole Oceanographic Institution Woods Hole MA USA Department of Ocean Engineering Massachusetts Institute of Technology Cambridge MA USA

This paper presents the novel insight that the SLAM information matrix is exactly sparse in a delayed-state framework. Such a framework is used in view-based representations of the environment which rely upon scan-matching raw sensor data. Scan-matching raw data results in virtual observations of robot motion with respect to a place its previously been. The exact sparseness of the delayed-state information matrix is in contrast to other recent feature based SLAM information algorithms like Sparse Extended Information Filters or Thin Junction Tree Filters. These methods have to make approximations in order to force the feature-based SLAM information matrix to be sparse. The benefit of the exact sparseness of the delayed-state framework is that it allows one to take advantage of the information space parameterization without having to make any approximations. Therefore, it can produce equivalent results to the “full-covariance” solution.

关键词： Delay Simultaneous localization and mapping Navigation Cameras Oceans Information filters Sparse matrices Information filtering Remotely operated vehicles Robot vision systems

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A technique for generating synthetic acoustic fields in shallow water

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The Journal of the Acoustical Society of America 2005年第S1期76卷 S11-S11页

作者： Michael S. Wengrovitz George V. Frisk MIT/WHOI Joint Program in Oceanography/Oceanographic Engineering Woods Hole MA 02543 Woods Hole Oceanographic Institution Woods Hole MA 02543

A numerical scheme for generating both the trapped mode and continuum portions of acoustic fields for a horizontally stratified ocean and bottom is presented. The technique is based on the fact that the branch line integral corresponding to the continuum portion of the field can be performed by Hankel transforming a modified Green's function. The modified Green's function is obtained by removing the pole contributions from the actual Green's function. The continuum portion is then added to the trapped mode portion to form the total synthetic field. The technique has the advantage that it is fast, accurate, and can be used for a more general geoacoustic model than the Pekeris waveguide. Synthetic results for several examples are presented and discussed.

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