Autonomous Underwater Gliders

Office of Naval Research N000141010022, collaboration with C. Woolsey
(Office of Naval Research DURIP N000140810827)

Undersea gliders are highly efficient, winged autonomous underwater vehicles (AUVs) which locomote by modulating their buoyancy and their attitude. The exceptional endurance of undersea gliders can be attributed to two key characteristics: robustness and efficiency. Both of these characteristics owe to the vehicles' reliance on gravity (weight and buoyancy) for propulsion and attitude control. Undersea gliders are robust because their directional control effectors (a system of moving masses) are housed internally, where they are protected from damage and corrosion. Undersea gliders are efficient because they spend most of their time in stable, steady motion, expending control energy only when changing their equilibrium state. While undersea gliders locomote with remarkable efficiency, even greater energy savings can be realized through the design of clever behaviors. For example, a control system which effects a desired state of steady motion directly, using advance knowledge of the required actuator configuration, will be more efficient than a control system which merely reacts to errors in the desired state of motion through feedback. The primary objective of the proposed work is to implement and evaluate a combined feedforward/feedback motion control system which maintains a prescribed steady motion corresponding to a desired speed, turn rate, and glide path angle. The secondary objective of the proposed work is to implement and evaluate some recently developed maneuvering strategies aimed at enhancing glider eciency. Our ultimate aim is to develop implementable, energy-efficient motion control strategies that further improve the inherent efficiency of these vehicles. The primary outcomes of the proposed experimental research program will be the experimental evaluation of proposed behaviors for existing undersea gliders.