Efficient control based on a verified model for an autonomous underwater vehicle : a case study of Autonomous Benthic Explorer

Abstract

The Autonomous Benthic Explorer (ABE) is an unmanned underwater vehicle being developed for scientific study of the deep ocean sea:floor. ABE will be completely autonomous from the surface which means that the lifetime of the mission will depend largely on how the vehicle is controlled. An accurate system model is critical for the controller development and trajectory planning. A model of the ABE vehicle dynamics is formulated for surge, heave and pitch motions. These motions in the lon,gitudinal plane are particularly important for the basic ABE trajectories of forward flight, depth changes and maneuvers involving both. A scale model of the ABE vehicle was towed to determine the lift/drag relationships to nonzero angles of attack. The experimental results are used in conjunction with traditional analytical techniques to generate a model of the longitudinal dynamics. The ABE model was studied in simulation over anticipated vehicle trajectories. A proportional plus derivative controller and a sliding mode controller were developed for tracking control. The power consumptions for different controllers and trajectories are examined. The results of this study will be incorporated in the final ABE design.