Six degree of freedom vehicle controller design for the operation of an unmanned underwater vehicle in a shallow water environment.
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Authors
Hajosy, Michael F.
Subjects
Advisors
Yoerger, Dana R.
Date of Issue
1994-09
Date
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
Closed loop control of an unmanned underwater vehicle (UUV) in the dynamically
difficult environment of shallow water requires explicit consideration of the highly
coupled nature of the governing non-linear equations of motion. This coupling between
an UUV's six degrees of freedom (6 DOF) is particularly important when attempting
complex maneuvers such as coordinated turns (e.g. simultaneous dive and heading
change) or vehicle hovering in such an environment. Given the parameter and modelling
uncertainties endemic to these equations of motion, then a robust 6 DOF sliding controller employing six-element vector sliding surfaces provides a framework in which satisfactory
UUV control can be achieved in shallow water. The vehicle equations of motion are developed and cast in a form that is amenable
to non-linear sliding control design. A complete 6 DOF sliding controller with vector
sliding surfaces is then formulated via a Lyapunov-like analysis. The sliding controller
is then modified via a weighted least-squares approach to work with a particular UUV
which has only 4 DOF control authority available. The modified controller is shown to work well for a variety of commanded UUV maneuvers in the presence of significant
environmental disturbances and vehicle hydrodynamic parameter uncertainties via
numerical simulation. Use of the signals generated by the controller are shown to be of
utility in vehicle buoyancy control.
Type
Thesis
Description
Series/Report No
Department
Ocean Engineering
Mechanical Engineering
Organization
Identifiers
NPS Report Number
Sponsors
Funding
Format
95 leaves.
Citation
Distribution Statement
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.