ABSTRACT

A nonlinear, 6 degree-of-freedom maneuvering dynamics and control simulator for the Theseus autonomous underwater vehicle (AUV) has been validated against several sets of full scale trials and independent predictive methods. The vehicle hydrodynamic coefficients are estimated with standard theoretical and empirical methods augmented with towing tank test results. The control algorithm implemented in the simulator is the same as the one used in the actual vehicle. A propulsion model makes it possible to optimize vehicle range and transit speeds as the battery capacity changes during the mission. The simulated vehicle response compares well against full scale sea trials data. The paper discusses the simulator validation and its use for vehicle design and mission applications.

INTRODUCTION

In 1992, Defence Research Establishment Pacific (now amalgamated with Defence Research Establishment Atlantic (DREA)) contracted ISE Research Ltd. (ISER) to build an AUV capable of laying cable under Arctic ice. ISER designed and built the Theseus AUV shown in Figure 1 for a 450 km range, a cruising speed of 2 m/s, a working depth of 1000 m, and with variable ballast tanks fore and aft. With a 2.44 m long by 1.12 m diameter payload bay and additional ballast tanks to correct for deploying cable, Theseus can lay up to 220 km of fiber-optic cable in its current configuration. The vehicle has a modular design for ease of transport, fault-tolerant control software, navigational accuracy to better than 0.5% of distance traveled (cross track error is much better), acoustic and fiber-optic telemetry systems, and terminal acoustic homing (Ferguson et al, 1995). In April 1995, Theseus went on its first Arctic mission in the ice covered waters offEllesmere Island, Canada. The successful trial verified launch and recovery procedures, tested all vehicle systems in an under-ice environment (navigation, telemetry, cable deployment, etc.)

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