Enhancement of the inertial navigation system for the Florida Atlantic University autonomous underwater vehicles

This thesis describes a new Inertial Navigation System (INS), designed for use on the latest generation of Autonomous Underwater Vehicle (AUV), the Morpheus AUVs, developed by the Department of Ocean Engineering. The INS makes use of a high precision Inertial Measurement Unit (IMU) along with a Doppler Velocity Log (DVL), a GPS/DGPS system and a flux gate magnetic compass to estimate the position of the vehicle during a mission. Extensive data processing methods are used in order to reduce the sources of error most critical to the navigation estimation. Accelerometers and gyroscopes are used to estimate the vehicle attitude in a complementary filter; a standard Kalman filter performs yaw rate bias estimation, whereas a second, extended Kalman filter, provides position estimation of the vehicle in real time, while also correcting for heading errors. Overall the INS is capable of providing the Morpheus with 1% navigation accuracy over an hour.