Type of Document Master's Thesis Author Nickell, Christopher Lee Author's Email Address email@example.com URN etd-09122005-121951 Title Modular Modification of a Buoyant AUV for Low-Speed Operation Degree Master of Science Department Aerospace and Ocean Engineering Advisory Committee
Advisor Name Title Woolsey, Craig A. Committee Chair Schaub, Hanspeter Committee Member Stilwell, Daniel J. Committee Member Keywords
- Autonomous Underwater Vehicle
- Moving Mass
- Internal Actuation
Date of Defense 2005-09-09 Availability unrestricted AbstractConventional streamlined autonomous underwater vehicles (AUVs) with a single thruster and stern planes are typically trimmed to be somewhat buoyant or heavy in water. To
maintain depth, they must generate a constant hydrodynamic force which requires that they swim at a constant pitch angle. Although tail fins are the typical mechanism for
generating this control moment, they become ineffective at low speeds. To enable an existing AUV to travel at lower speeds, one may easily incorporate a modular moving mass
actuator. In some cases, it may also be advantageous to include a fixed wing.
The equations of motion and equilibrium conditions to regulate depth are derived, and the effectiveness and low-speed efficiency of a fixed wing is evaluated. The effect of the
vertical offset of the moving mass is analyzed to establish the relation between the control angle and the moving mass linear position.
A description of the design of a one degree of freedom moving mass actuator module and preliminary experiments using the Virginia Tech Miniature AUV is provided. Data is
presented for a series of fixed MMA position experiments as well as a dynamic position test. The results illustrate the effectiveness of a moving mass actuator at generating
low-speed control moments. With the collected data, parameter identification is performed to get an estimate of the hydrodynamic parameters.
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