Longitudinal Control Design and Performance Evaluation for the Nereus 11,000 m Underwater Vehicle

This paper reports the predicted performance of a flight-control system for Nereus, a new underwater vehicle designed for oceanographic operations to 11,000 m depth. We investigated three operating configurations: (a) a vectored thrust dynamic foil configuration suited for zero speed hover through intermediate speeds; (b) a level flight mode suited to modest climb angles, and (c) a pitching flight mode suited to high speed operation. We report the terrain-following performance attained by each in simulation. Our simulations employ a simple non- linear longitudinal plane dynamics model supplemented at low angles of attack by a high-fidelity model provided to us by Vehicle Control Technologies of Reston VA. Terrain-following performance is specified as an operating envelope that describes attainable climb angle versus forward speed for a given height- above-bottom tolerance.