Acoustic motion estimation and guidance for unmanned underwater vehicles

The problem of navigation, guidance and control of Unmanned Underwater Vehicles (UUVs) is addressed in this paper. A task-function based guidance system and an acoustic motion estimation module have been integrated with a conventional UUV autopilot within a two-layered hierarchical architecture for closed-loop control. The design of the guidance system is based on suitable Lyapunov functions that can handle the different manoeuvres involved in approaching a target. Range and bearing information provided by a pencil beam profiling sonar are processed by an Extended Kalman Filter based algorithm for motion estimation in a structured environment. The resulting Navigation Guidance and Control (NGC) system has been tested on Roby2, the UUV testbed developed at the Istituto Automazione Navale of Italy's National Research Council. The experimental set-up as well as modalities and results are discussed.