Sigma-point Unscented Kalman Filter used for AUV navigation

This paper presents an implementation of the Sigma-point Unscented Kalman Filter (SP-UKF) used in the simulated task of open-water navigation of two types of AUV. The first simulated vehicle is a large cruise-type vehicle modeled after the Instituto Superior Tecnico, Lisbon vehicle Infante. The second is a small, almost fully actuated vehicle with tunnel thrusters modeled after the SSC Pacific, San Diego vehicle CETUS II. The SP-UKF shows itself, after properly taking care of implementation details, to be a robust methodology which allows for efficient and correct navigation, aided by several typical sensors (DVL, USBL hydroacoustic localization systems, AHRS). The influence of currents on the navigation, and the ability of estimating the current components is also researched. The navigation fix is fed back to the low-level control loops aboard each vehicles to achieve sane and rational navigation of the waterspace that follows stably and robustly the command signals.