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

Concurrent non-ketotic hyperglycinemia and propionic acidemia in an eight year old boy

This is the first reported case of a patient with both non-ketotic hyperglycinemia and propionic acidemia. At 2 years of age, the patient was diagnosed with non-ketotic hyperglycinemia by elevated glycine levels and mutations in the GLDC gene (paternal allele: c.1576_1577insC delT and c.1580delGinsCAA; p.S527Tfs*13, and maternal allele: c.1819G\u3eA; p.G607S). At 8 years of age after having been placed on ketogenic diet, he became lethargic and had severe metabolic acidosis with ketonuria. Urine organic acid analysis and plasma acylcarnitine profile were consistent with propionic acidemia. He was found to have an apparently homozygous mutation in the PCCB gene: c.49C\u3eA; p.Leu17Met. The patient was also treated with natural protein restriction, carnitine, biotin, and thiamine and had subjective and biochemical improvement

Doxycycline for Malaria Chemoprophylaxis and Treatment: Report from the CDC Expert Meeting on Malaria Chemoprophylaxis

Doxycycline, a synthetically derived tetracycline, is a partially efficacious causal prophylactic (liver stage of Plasmodium) drug and a slow acting blood schizontocidal agent highly effective for the prevention of malaria. When used in conjunction with a fast acting schizontocidal agent, it is also highly effective for malaria treatment. Doxycycline is especially useful as a prophylaxis in areas with chloroquine and multidrug-resistant Plasmodium falciparum malaria. Although not recommended for pregnant women and children < 8 years of age, severe adverse events are rarely reported for doxycycline. This report examines the evidence behind current recommendations for the use of doxycycline for malaria and summarizes the available literature on its safety and tolerability

Real-time SLAM with Piecewise-planar Surface Models and Sparse 3D Point Clouds

Abstract — This paper reports on the use of planar patches as features in a real-time simultaneous localization and mapping (SLAM) system to model smooth surfaces as piecewise-planar. This approach works well for using observed point clouds to correct odometry error, even when the point cloud is sparse. Such sparse point clouds are easily derived by Doppler velocity log sensors for underwater navigation. Each planar patch contained in this point cloud can be constrained in a factorgraph-based approach to SLAM so that neighboring patches are sufficiently coplanar so as to constrain the robot trajectory, but not so much so that the curvature of the surface is lost in the representation. To validate our approach, we simulated a virtual 6-degree of freedom robot performing a spiral-like survey of a sphere, and provide real-world experimental results for an autonomous underwater vehicle used for automated ship hull inspection. We demonstrate that using the sparse 3D point cloud greatly improves the self-consistency of the map. Furthermore, the use of our piecewise-planar framework provides an additional constraint to multi-session underwater SLAM, improving performance over monocular camera measurements alone. I

Building 3D mosaics from an Autonomous Underwater Vehicle, Doppler velocity log, and 2D imaging sonar

AbstractThis paper reports on a 3D photomosaicing pipeline using data collected from an autonomous underwa-ter vehicle performing simultaneous localization and mapping (SLAM). The pipeline projects and blends 2D imaging sonar data onto a large-scale 3D mesh that is either given a priori or derived from SLAM. Compared to other methods that generate a 2D-only mosaic, our approach produces 3D models that are more structurally representative of the environment being surveyed. Additionally, our system leverages recent work in underwater SLAM using sparse point clouds derived from Doppler velocity log range returns to relax the need for a prior model. We show that the method produces reasonably accurate surface reconstruction and blending consistency, with and without the use of a prior mesh. We experimentally evaluate our approach with a Hovering Autonomous Underwater Vehicle (HAUV) performing inspection of a large underwater ship hull. I

High-resolution underwater robotic vision-based mapping and three-dimensional reconstruction for archaeology

Documenting underwater archaeological sites is an extremely challenging problem. Sites covering large areas are particularly daunting for traditional techniques. In this paper, we present a novel approach to this problem using both an autonomous underwater vehicle (AUV) and a diver-controlled stereo imaging platform to document the submerged Bronze Age city at Pavlopetri, Greece. The result is a three-dimensional (3D) reconstruction covering 26,600 m2 at a resolution of 2 mm/pixel, the largest-scale underwater optical 3D map, at such a resolution, in the world to date. We discuss the advances necessary to achieve this result, including i) an approach to color correct large numbers of images at varying altitudes and over varying bottom types; ii) a large-scale bundle adjustment framework that is capable of handling upward of 400,000 stereo images; and iii) a novel approach to the registration and rapid documentation of an underwater excavations area that can quickly produce maps of site change. We present visual and quantitative comparisons to the authors' previous underwater mapping approaches

Concurrent non-ketotic hyperglycinemia and propionic acidemia in an eight year old boy

This is the first reported case of a patient with both non-ketotic hyperglycinemia and propionic acidemia. At 2 years of age, the patient was diagnosed with non-ketotic hyperglycinemia by elevated glycine levels and mutations in the GLDC gene (paternal allele: c.1576_1577insC delT and c.1580delGinsCAA; p.S527Tfs*13, and maternal allele: c.1819G>A; p.G607S). At 8 years of age after having been placed on ketogenic diet, he became lethargic and had severe metabolic acidosis with ketonuria. Urine organic acid analysis and plasma acylcarnitine profile were consistent with propionic acidemia. He was found to have an apparently homozygous mutation in the PCCB gene: c.49C>A; p.Leu17Met. The patient was also treated with natural protein restriction, carnitine, biotin, and thiamine and had subjective and biochemical improvement