Design and analysis of an improved Wave Glider recovery system

摘要

The Sensor Hosting Autonomous and Remote Craft (SHARC) Wave Glider system is an autonomous surface vehicle widely used for long-duration at-sea data collection and acoustic monitoring. The system is manufactured by Liquid Robotics Inc. (LRI) and consists of two components (1) a surface float housing sensors, batteries, solar panels, and communication systems, and (2) a submerged propulsor (glider) containing six hinged hydrofoils. A third component, a submerged body housing additional sensors, may be towed behind the propulsor. While system launch is relatively straight forward, recovery of the system is challenging and incurs high risk. Challenges include (1) the Wave Glider system contains multiple components, (2) forward motion of the system cannot easily be arrested, and (3) the ship conducting recovery operations often has a high freeboard. Need for an improved recovery system is desired, particularly for the United States Naval Oceanographic Office (NAVOCEANO), as current recovery methods require personnel in small boats or swimmers in the water to control the vehicle and attach lifting lines. These procedures are hazardous to both personnel and equipment and are limited to low sea states. This project, conducted by a team of five undergraduate students and two advisers, designed and evaluated multiple alternatives as viable recovery solutions. Based on design and operational requirements, the final proposed solution is two-part. The first is a remotely actuated inflatable lift bag attached to the stern of the submerged propulsor that will halt forward movement when inflated; and the second is a vertical cable loop mounted on the surface float to facilitate lifting of the float, propulsor and towed payloads. The proposed solution was demonstrated to be feasible and met all design requirements, with an emphasis on simplicity.