Sonar-based guidance of unmanned underwater vehicles

This paper addresses the problem of the design and coordination of guidance and sonar-based motion estimation algorithms for unmanned underwater vehic les. In the framework of a two-layered hierarchical architecture uncoupling the system's dynamics and kinematics, a couple of guidance laws for approa ching a target with the desired orientation and following an environmental feature have been designed with Lyapunov-based techniques. Suitable acousti c-based estimators of the corresponding operational variables have been des igned and integrated with the guidance and control system. A finite state m achine combined with a suitable interface for event generation allows the c oordinated execution of basic guidance and motion estimation tasks to carry out more complex functions. Experimental results of pool trials of a proto type unmanned underwater vehicle executing free-space maneuvering, wall-fol lowing, tasks and the more complex mission of following the perimeter of th e trial pool are reported and discussed.