A Software Architecture for a Small Autonomous Underwater Vehicle Navigation System

This thesis documents the development of an interim Small Autonomous Underwater Vehicle AUV Navigation System SANS, a self-contained, externally mountable navigation package. The purpose of SANS is to determine the position of a submerged object of interest located by an AUV. The volume of SANS must not exceed 120 cubic inches and total system accuracy of 10.0 meters rms or better is required. An Inertial Navigation System INS is implemented to compute the ascent path during transit from an object of interest to the surface. INS hardware components include miniature spin gyroscopes, a compass and a depth transducer interfaced through an analog to digital converter. Global Positioning System GPS is used to determine the AUVs location after reaching the surface. The reciprocal of the ascent vector is applied to the AUVs GPS position to accurately determine the location of the target of interest. A primarily object- oriented software architecture is implemented here with extensive software testing to verify the proper operation of key modules. The objective of this thesis is to quantify the adequacy of the selected components in meeting these requirements and to develop a breadboard design demonstrating the basic functions of the interim SANS. This research concludes that the components selected for the interim SANS meet the accuracy requirements provided the AUV maintains a climb angle which is equal to or steeper than 12 degrees from a typical mission depth of 20 meters.