Fusing Hydroacoustic Absolute Position Fixes With AUV On-Board Dead Reckoning

This paper presents an implementation of the Sigma-point Unscented Kalman Filter (SP-UKF) used in the simulated task of open-water navigation of a large cruise-type autonomous underwater vehicle (AUV), the NPS*, Aries. Open-water navigation is conducted on the basis of rate gyros, the AHRS**, , which includes accelerometers and a triaxial magnetic compass, and the DVL***, . All sensors function at many times the sampling time of the control loops, and therefore are available (with even the possibility of median or other filtering) at every sample time. Additionally, to correct for unavoidable dead reckoning drift, an inverted USBL**** system is used to sporadically fuse an absolute navigation fix with the projected solution of the dead reckoning navigation. The entire simulation environment includes a detailed dynamical model of the vehicle, non-stationary, non-Gaussian measurement noise generators, sporadic sensor failure and sliding mode controllers for heading, pitch and forward speed.