Navigation is a critical requirement for the operation of autonomous underwater vehicles (AUVs). In this paper we present acoustic navigation results for the Odyssey II AUV obtained by using a Kalman filter that integrates dead-reckoning with acoustic range measurements made to an array of acoustic beacons pre-deployed in the operating environment. Because spurious acoustic measurements due to multipath propagation are common, initialization and outlier rejection techniques are addressed. The navigation algorithm has been extensively tested by post-processing of real data acquired by Odyssey II during field operations in a variety of environments. These include the Charles River Basin, the Atlantic Ocean (1.5 km off the Florida coast), and the Pacific Ocean (375 km off the Oregon coast). Our results show improved performance over prior techniques based exclusively on fix computation and dead reckoning.

This paper presents an algorithm which allows an AUV to reset its localization (position and orientation) and to estimate the water current while moving in the vicinity of two acoustic beacons. The algorithm is based on a Kalman filter which integrates the measurements provided by an ultra short base line array located in the vehicle, a Doppler log, a depthmeter and an attitude and heading reference system. After such an estimation phase, the vehicle can start to dead reckon away from the beacons in the best conditions and come back for a reset when necessary. Various considerations about the algorithm allow us to introduce the concept of 'navigation supervisor' currently under development at IFREMER. This study is conducted based on the work previously done for implementation of high-level intelligent control and mission programming.