A novel class of small low-cost unmanned underwater vehicles (UUVs) is beginning to perform oceanographic, environmental assessment, and national security missions that are faster and less expensive than previous methods such as large high-cost UUVs, human-piloted vehicles, and human divers. A significant limitation of small low-cost UUVs is their low-cost navigation systems which presently limit them to missions requiring comparatively low-precision navigation. This project is developing new methods for high-accuracy navigation with low-cost sensors to provide dramatically improved navigation accuracy for low-cost UUVs. The three-part approach (1) employs Doppler sonar velocity measurement and low-cost low-power inertial measurement units to estimate attitude; (2) develops nonlinear model-based state estimators employing a full nonlinear model of the vehicle's second order plant dynamics; and (3) utilizes underwater acoustic modem networks to provide simultaneous acoustic communication and acoustic range and range-rate data, and employ these data for improved underwater vehicle navigation. Experimental validation of these methods includes full-scale experimental trials with two disparate testbed underwater vehicles. Dissemination of the results includes research publications and more general public outreach. This project involves hands-on training and mentoring of undergraduate students and graduate students. The undergraduates will be involved in the research, and will also serve as mentors in a program which provides introductory engineering experiences for middle school girls in the Baltimore area through half-day weekend programs on the Johns Hopkins University campus. This research will enable UUVs to perform missions requiring high navigation accuracy that are presently considered either impractical or infeasible with existing low-cost UUVs.
