16 research outputs found
Advances in Simultaneous Localization and Mapping in Confined Underwater Environments Using Sonar and Optical Imaging.
This thesis reports on the incorporation of surface information into a probabilistic simultaneous localization and mapping (SLAM) framework used on an autonomous underwater vehicle (AUV) designed for underwater inspection. AUVs operating in cluttered underwater environments, such as ship hulls or dams, are commonly equipped with Doppler-based sensors, which---in addition to navigation---provide a sparse representation of the environment in the form of a three-dimensional (3D) point cloud. The goal of this thesis is to develop perceptual algorithms that take full advantage of these sparse observations for correcting navigational drift and building a model of the environment. In particular, we focus on three objectives. First, we introduce a novel representation of this 3D point cloud as collections of planar features arranged in a factor graph. This factor graph representation probabalistically infers the spatial arrangement of each planar segment and can effectively model smooth surfaces (such as a ship hull). Second, we show how this technique can produce 3D models that serve as input to our pipeline that produces the first-ever 3D photomosaics using a two-dimensional (2D) imaging sonar. Finally, we propose a model-assisted bundle adjustment (BA) framework that allows for robust registration between surfaces observed from a Doppler sensor and visual features detected from optical images. Throughout this thesis, we show methods that produce 3D photomosaics using a combination of triangular meshes (derived from our SLAM framework or given a-priori), optical images, and sonar images. Overall, the contributions of this thesis greatly increase the accuracy, reliability, and utility of in-water ship hull inspection with AUVs despite the challenges they face in underwater environments.
We provide results using the Hovering Autonomous Underwater Vehicle (HAUV) for autonomous ship hull inspection, which serves as the primary testbed for the algorithms presented in this thesis. The sensor payload of the HAUV consists primarily of: a Doppler velocity log (DVL) for underwater navigation and ranging, monocular and stereo cameras, and---for some applications---an imaging sonar.PhDElectrical Engineering: SystemsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/120750/1/paulozog_1.pd
NASA Tech Briefs, Winter 1980
Topics include: NASA TU Services: Technology Utilization services that can assist you In learning about and applying NASA technology; New Product Ideas: A summary of selected innovations of value to manufacturers for the development of new products; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Life Sciences; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences
Advanced Automation for Space Missions
The feasibility of using machine intelligence, including automation and robotics, in future space missions was studied
Obiter Dicta
"Stitched together over five years of journaling, Obiter Dicta is a commonplace book of freewheeling explorations representing the transcription of a dozen notebooks, since painstakingly reimagined for publication. Organized after Theodor Adornoâs Minima Moralia, this unschooled exercise in aesthetic thoughtâgleefully dilettantish, oftentimes dangerously close to the epigrammaticâinterrogates an array of subject matter (although inescapably circling back to the curiously resemblant histories of Western visual art and instrumental music) through the lens of drive-by speculation. Erick Verranâs approach to philosophical inquiry follows the brute-force literary technique of Jacques Derrida to exhaustively favor the material grammar of a signifier over hand-me-down meaning, juxtaposing outer semblances with their buried systems and our etched-in-stone intuitions about color and illusion, shape and value, with lessons stolen from seemingly unrelatable disciplines.
Interlarded with extracts of Ludwig Wittgenstein but also Wallace Stevens, Cormac McCarthy as well as Roland Barthes, this cache of incidental remarks eschews whatâs granular for the biggest picture available, leaving below the hyper-specialized fields of academia for a birdâs-eye view of their crop circles. Obiter Dicta is an unapologetic experiment in intellectual dot-connecting that challenges much long-standing wisdom about everything from illuminated manuscripts to Minecraft and the evolution of European music with lyrical brevity; that is, before jumping to the next topic.
Infrastructure and the Remaking of Asia
Infrastructure and the Remaking of Asia offers a new understanding of how technological innovation, geopolitical ambitions, and social change converge and cross-fertilize one another through infrastructure projects in Asia. This volume powerfully illustrates the multifaceted connections between infrastructure and three global paradigm shifts: climate change, digitalization, and Chinaâs emergence as a superpower. Drawing on fine-grained analyses of airports, highways, pipelines, and digital communication systems, the book investigates infrastructure both âfrom above,â as perceived by experts and decision makers, and âfrom below,â as experienced by middlemen, laborers, and everyday users. In so doing, it provides groundbreaking insights into infrastructureâs planning, production, and operation.
Focusing on cities and regions across Asia, the volume combines ten tightly interwoven case studies, from the Bosphorus to Beijing and from the Indonesian archipelago to the Arctic. Written by leading global infrastructure experts in the fields of anthropology, architecture, geography, history, science and technology studies, and urban planning, the book establishes a dialogue between scholarly approaches to infrastructure and the more operational perspective of the professionals who design and build it. This multidisciplinary method sheds light on the practitionersâ mindset, while also attending to the materiality and agency of the infrastructures that they create. Infrastructure and the Remaking of Asia is conceived as an act of translation: linking up relatedâyet thus far disconnectedâresearch across a variety of academic disciplines, while making those insights accessible to a wider audience of students, infrastructure professionals, and the general public
NASA Tech Briefs, October 1993
Topics include: Sensors; esign and Engineering; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication technology; Mathematics and Information Sciences; Life Sciences; Books and Reports
Examination of volcanism and impact cratering on terrestrial bodies
Thesis (Ph.D.) University of Alaska Fairbanks, 2023Exploring and expanding our understanding of the planets (i.e., planetary science) encompasses a vast array of topics and disciplines. This dissertation concentrates on the surficial processes of and examination of terrestrial planets, primarily via the study of volcanism and impact cratering. The first project starts with an exploration of NIR remote sensing techniques as applied to Venus. This work found that NIR remote sensing at the clement conditions just beneath the cloud deck provide vastly improved imaging capability. This improved visibility is most notable for the tesserae, regions of Venus of great interest to the scientific community. Radar imagery and derived data products were then used to survey 21 mid-sized volcanoes on the surface of Venus. Similar to volcanoes at larger diameters, the midsized volcanoes of Venus are significantly flatter than those on other terrestrial bodies. Several of these volcanoes also show deformation that requires a negligibly thin lithosphere some time after the emplacement of the construct. The third project then evaluates the hazards involved with safely placing a lander on the Venusian tesserae and examines potential methods by which to detect and then avoid these hazards. Safely placing a suite of scientific instruments on tesserae is necessary to answer long-standing questions about Venus. Current technologies put relevant hazards at the edge of detection (i.e., zero fault tolerance) and can execute divert maneuvers of only a few tens of meters. Investment in hazard detection and avoidance technologies is necessary to bring safety margins to acceptable levels; data from future missions - while helpful - will be insufficient to select safe landing zones prior to launch. Oblique impact cratering is a ubiquitous event (approximately half of all impacts are at 45 or less). Our poor understanding of this process leaves a significant amount of information buried and waiting to be uncovered. Low-velocity oblique impact experiments were conducted at John's Hopkins University's Applied Physics Laboratory Planetary Impact Lab to better understand the oblique impact process and prepare for high velocity experiments at similar impact angles. These experiments also sought to understand the effect of target tilt, which is currently necessary at existing experimental facilities in order to simulate changes in impact angle smaller than 15°. These experiments show that target tilt significantly amplifies oblique characteristics (e.g., aspect ratio, butterfly ejecta). The time-delayed and spatially offset transference of energy from the impactor to the target is important in determining the excavation process and final crater morphology and ejecta distribution
Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14
Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences