Simulation-Based Validation of Navigation Filter Software for a Shallow Water AUV Navigation System (SANS)

This is a NAVAL POSTGRADUATE SCHOOL MONTEREY CA report procured by the Pentagon and made available for public release. It has been reproduced in the best form available to the Pentagon. It is not spiral-bound, but rather assembled with Velobinding in a soft, white linen cover. The Storming Media report number is A351803. The abstract provided by the Pentagon follows: Navigation filter software is currently being developed for an inertial navigation system without rotating gyros. This system shall replace the navigation system that is currently used in the Phoenix Autonomous Underwater Vehicle of the Naval Postgraduate School. The filter combines acceleration sensors, angular rate sensors, a water speed sensor, a magnetic compass and a GPS system. The harmonization of the sensors is performed by gain matrices. The filter code must be tested for correctness and evaluated, and optimal values for the gain matrices must be found. Both factors directly influence the accuracy of the computed positions, and thus the quality of AUV navigation. in this thesis, the Kalman filter code is tested by experimentation with a simulation of a submarine. Two versions of the code are available, both written in LISP and C++. Test runs are performed in different simulated sea-states (water current), with and without noise added to the sensors, and with different values for the gain matrices. Based on the experiments, the Kalman filter code seems to be correct and stable. Noise is the most important determinant of the filter performance. The results can be optimized by careful fine tuning of the gain matrices.