Energy-efficient underwater surveillance by means of hybrid aquacopters
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Authors
Dillard, Chase H.
Subjects
AquaQuad
path planning
rapidly-exploring random tree
unscentedKalman filter
nonlinear estimation
time-difference of arrival
dilution of precision
path planning
rapidly-exploring random tree
unscentedKalman filter
nonlinear estimation
time-difference of arrival
dilution of precision
Advisors
Dobrokhodov, Vladimir
Jones, Kevin
Date of Issue
2014-12
Date
Dec-14
Publisher
Monterey, California: Naval Postgraduate School
Language
Abstract
This thesis develops algorithms in support of a prototype hybrid air-water quadcopter platform: the AquaQuad. We consider the scenario in which AquaQuads with underwater acoustic sensing capabilities are tracking a submerged target from the surface of the ocean using sparse distributed measurements. Multiple nonlinear estimation filters are evaluated for the tracking scenario, resulting in the selection of the unscentedKalman filter (UKF). Geometric positioning effects on estimators are explored through analysis of the horizontal dilution of precision metric. The UKF is then implemented in real-time on quadrotors using time-difference of arrival pseudo-measurements in an instrumented Vicon lab space. The AquaQuads will primarily drift, but possess battery-limited flight capabilities. To increase on-station time, we seek to maximize use of the environment. In addition to solar energy, we take advantage of ocean currents that traditional autonomous platforms seek to reject. A novel sampling-based approach for path-planning is therefore created and lab-tested. The new algorithm, Dead-Reckoning Rapidly-Exploring Random Tree Star (DR-RRT*), combines the infinite-time optimality guarantees of RRT* with the unique AquaQuad mobility requirements. The DR-RRT* develops obstacle-free paths to a goal by linking brief flight and energy-efficient drift segments together, resulting in an energy savings of 27 percent over direct flight.
Type
Thesis
Description
Series/Report No
Department
Mechanical and Aerospace Engineering (MAE)
Organization
Identifiers
NPS Report Number
Sponsors
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Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.