AUV navigation: increased robustness and efficiency by fusion of active and passive modes

We describe the positioning system of MAUVE, a miniaturized inexpensive underwater platform dedicated to the surveillance of coastal regions. MAUVE can navigate in three distinct modes (active, passive and inertial). In active mode position is directly observed, but energy consumption is non-negligible. In passive mode one component of position is not observable, however, it requires no additional energy. In inertial mode, positioning basically integrates on-board proprioceptive measures, leading to a strictly increasing error. We show that, by critically interleaving the use of these three modes, efficient tracking of a pre-specified trajectory can be achieved with a minimal penalty in consumed energy. Additionally, the paper proposes an autonomy monitoring indicator that flags the situations where vehicle recuperation can be in danger.