Title page for ETD etd-04242009-143215


Type of Document Dissertation
Author Petrich, Jan
URN etd-04242009-143215
Title Improved Guidance, Navigation, and Control for Autonomous Underwater Vehicles: Theory and Experiment
Degree PhD
Department Electrical and Computer Engineering
Advisory Committee
Advisor Name Title
Stilwell, Daniel J. Committee Chair
Abbott, A. Lynn Committee Member
Lindner, Douglas K. Committee Member
Neu, Wayne L. Committee Member
Woolsey, Craig A. Committee Member
Keywords
  • Flow Field Identification
  • Equivalent Models
  • Autonomous Underwater Vehicles
  • System Identification
  • Uniform Observability
  • Gyroscope Calibration
  • Pitch and Yaw Coupling
  • H∞ Control
  • Persistence of Excitation
Date of Defense 2009-04-17
Availability unrestricted
Abstract
This dissertation addresses attitude control and inertial navigation of autonomous underwater vehicles (AUVs). We present theoretical justification for using simplified models, derive system identification algorithms, and verify our results through extensive field trials. Although this research focuses on small AUVs with limited instrumentation, the results are useful for underwater vehicles of any size.

For attitude control of aircraft systems, second-order equivalent pitch-axis models are common and extensively studied. However, similar analysis has not been performed for the pitch-axis motion of underwater vehicles. In this dissertation, we study the utility and the limitations of second-order approximate models for AUVs. We seek to improve the flight performance and shorten the time required to re-design a control algorithm when the shape, mass-distribution, and/or net buoyancy of an AUV/payload configuration changes.

In comparison to commonly implemented AUV attitude controllers, which neglect roll motion and address pitch and yaw dynamics separately, we derive a novel linear time-varying model that explicitly displays the coupling between pitch and yaw motion due to nonzero roll angle and/or roll rate. The model facilitates an H∞ control design approach that explicitly addresses robustness against those coupling terms and significantly reduces the effect of pitch and yaw coupling.

To improve AUV navigation, we investigate algorithms for calibrating a triaxial gyroscope using angular orientation measurements and formally define AUV trajectories that are persistently exciting and for which the calibration coefficients are uniformly observable. To improve AUV guidance, we propose a near real-time ocean current identification method that estimates a non-uniform flow-field using only sparse flow measurements.

Files
  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  PhD_Dissertation_JanPetrich.pdf 2.76 Mb 00:12:47 00:06:34 00:05:45 00:02:52 00:00:14

Browse All Available ETDs by ( Author | Department )

dla home
etds imagebase journals news ereserve special collections
virgnia tech home contact dla university libraries

If you have questions or technical problems, please Contact DLA.