Precision Maritime Inshore Navigation with a Tightly-Coupled Sensor System

This paper describes an integrated sensor system for precision maritime surface navigation in tightly confined harbor environments. The system tightly integrates GPS, inertial, image and laser measurements with an onboard electronic charting system to provide accurate bearing and/or range measurements to known navigational aids, allowing robust and accurate piloting relative to navigation aids and hazards. The system provides the ability to input automatic visual fixes into an ECDIS-N electronic charting system with little operator involvement. The system architecture is described, navigation integration and automatic calibration techniques are derived, and results reported. In the summer of 2002, two of the systems, integrated with an onboard electronic charting system, were tested at sea near Annapolis, MD. The results of the trials showed the ability of the system to improve the accuracy by a factor of 10 over current visual fix methods. At the same time, the system improves the frequency and timeliness of visual fixes while reducing crew workload when compared with current piloting techniques.