Abstract:
Closed loop control of an underwater vehicle in an acoustic position net requires an
accurate hydrodynamic model of the vehicle. The model is essential to the control
algorithm design process. Further, it is an integral part of the observer used to
generate complete state estimates from the position measurements. An experimental
apparatus and numerical analysis technique for vehicle system identification during
the thruster induced hover limit cycle are described. Detailed comparisons to other
techniques are made and extension of the technique to four degrees of freedom with
coupling is discussed. A model of the Remotely Operated Vehicle Hylas is determined.
The model determined by the system identification procedure is then used in the
designs of a state estimator and controller for trajectory following by the vehicle.
The algorithms are initially evaluated in a numerical simulation. Tests are made for
stability, trajectory following performance, and accuracy of the state estimator under
varying system and environmental conditions.
Finally, the results of vehicle trials are presented. System stability and accurate
trajectory following under the control of the algorithms are demonstrated using ROY
Hylas. The high accuracy level of the simulation is also demonstrated by the trials
and directions for continued research are discussed.
