Decentralized Navigation for Multiple Underwater Vehicles
Johns Hopkins University
Since their creation in the 1990s, autonomous underwater vehicles (AUVs) have been used to create maps of the ocean using a variety of oceanographic sensors. Recently, the advent of reliable, low-cost autonomous underwater vehicles is enabling the collection of scientific data sets that are impractical or impossible to collect with a single vehicle. The geospatial accuracy of these data sets is predicated on navigation accuracy of these vehicles, but we currently lack robust real-time multi-vehicle navigation algorithms. Because salt water is impervious to GPS signals, navigation underwater typically relies on acoustics. Traditional techniques for navigating underwater vehicles, designed for single-vehicle operations, do not scale well to multi-vehicle operations. To address these limitations we explore single-beacon navigation and decentralized estimation techniques.In this talk I will describe the acoustic communications (Acomms) system developed by myself and collaborators to combine acoustic communication and navigation for single-beacon navigation. The Acomms system has been installed on three Wood Hole Oceanographic Institution vehicles--Puma, Jaguar, and Nereus--and deployed in four sea trials around the world including in the Mariana Trench. I will describe two single-beacon acoustic navigation algorithms for underwater vehicles--a centralized algorithm, based on the extended Kalman filter (EKF), and a decentralized algorithm, based on the extended information filter (EIF)--and finish with a few sea stories from the Mariana Trench field trials.
Dr. Sarah E. Webster received a B. S. in Mechanical Engineering from the Massachusetts Institute of Technology in February 2000. Subsequently, she worked as an engineer at Woods Hole Oceanographic Institution (2000-2004) where she designed and built archaeological excavation technology for remotely operated underwater vehicles (ROVs). In August 2004, she enrolled in the Mechanical Engineering Ph.D. program at Johns Hopkins University where she designed an acoustic communication system for combined communication and navigation of underwater vehicles that has been deployed on three underwater vehicles during several scientific expedition around the world, including in the Mariana Trench. Dr. Webster completed her dissertation entitled "Decentralized Single-Beacon Acoustic Navigation: Combined Communication and Navigation for Underwater Vehicles" in June 2010.