Design and Analysis of a Novel Underwater Glider - RoBuoy

Abstract

Underwater gliders are special class of autonomous underwater vehicles (AUVs) proven to be power efficient with better range and endurance compared to the conventional underwater robots. Most of the existing underwater gliders use `change of mass' based variable buoyancy (VB) method in which the overall system architecture and construction are complex. A novel underwater glider RoBuoy based on the `change of volume' concept of variable buoyancy method is presented here. RoBuoy uses actuated metallic bellows to change the volume which makes the system simple and modular in construction without any compromise in the performance. It uses minimal number of parts compared to the existing gliders which reduces the overall complexity of the system. Also, most of the conventional gliders use the external fluid for its working which may result in corrosion or fouling of parts and requires frequent maintenance. In the proposed glider, all the vital parts required for its working, apart from the sensing payloads are enclosed inside the hull, thereby increasing the durability. In this paper, a detailed design of RoBuoy is discussed with its possible modes of operation. An integrated mathematical model considering the individual dynamics of the actuator, hull/fuselage, and the wings has been developed and the open loop performance of the glider is studied at different input conditions. An experimental prototype has been designed and fabricated based on optimized dimensions, with the required mechatronic system. Experiments have been conducted and the results prove the feasibility of the concept.