Networked Sensor Swarm of Underwater Drifters

Abstract

Although coastal waters play a crucial part in the ecosystem and economy, detailed monitoring of these areas has been difficult. This multi-institutional project presents a novel technology, where a large number of autonomous underwater vehicles organize themselves as a swarm, forming a dense four-dimensional spatio-temporal sampling system. The system's unique strength is that it consists of drifters that float with the coastal currents, thereby monitoring phenomena in their own moving frame of reference and allowing for revolutionary sampling densities due to relatively low vehicle cost.

To achieve this powerful new technology, the drifter swarm has to operate as an intelligent distributed collective, made possible by the cyber backbone of networked information sharing, location finding and swarm control. By its very nature, a networked drifter swarm is heavily affected by both the physical ocean environment, i.e. the currents, and the challenging underwater propagation medium. The cyber components are designed in way that is tightly matched to these physical factors. In addition to being tightly coupled to the physical world, these cyber challenges are also highly intertwined, necessitating research that is distinctly collaborative.

To support underwater communication links, a low-cost low-rate modem is being developed and preliminary sea-trials have been encouraging. Networking protocols, such as time synchronization and medium access, have been proposed that are optimized for the specifics of the propagation medium. In addition, position finding algorithms combine local information sharing, sensor data and correlations from current- induced motion behavior. A centralized solution allows for optimum post-facto data annotation, while a distributed algorithm is designed to support real-time formation control. In December 2011, the power of the localization algorithms was shown during sea-trials; and follow-up tests are planned for the second part of 2012. Formation control is being designed for the swarm to self-organize in advantageous configurations by taking advantage the spatio-temporal variability of the current flow field.

The resources of the project are also leveraged in various outreach activities. This includes participation in the 'Envision' event organized by the Society of Women Engineers at UCSD over the past two years, and pioneering a STEM related program with the Girl Scouts in San Diego County. This past summer, PI Jaffe ran a one week workshop on the use of the floats for 8 high school and junior high school teachers who took part in various activities related to the project, including at-sea experiments. In addition to participating in this workshop as well, PIs Schurgers and Kastner are faculty leaders in the COSMOS program; its goal is to expose and motivate young and creative high-school students to various disciplines including computer science and engineering.

Award ID: 1035828