This paper addresses the autonomous underwater vehicle (AUV) positioning by means of a single mobile acoustic beacon. It is assumed that beacon is towing by autonomous surface vehicle (ASV) in the operation area and its coordinates are determining by means of GPS. As the range measurement allows to localize AUV only in radial direction, the algorithm of beacon motion relative AUV is suggested. According with this algorithm, the mobile beacon moves in a circle around the moving AUV. Presented simulation results verify that using such technique allows to hold position error in desired bounds and to achieve adequate navigation accuracy of AUV.
Navigation support is a critical importance for successful execution of the missions by autonomous underwater vehicle (AUV). That is the reason why one of the main problems facing the researchers is development of reliable and precise navigation systems for AUV. Commonly AUV uses integrated positioning system (IPS) which based on reckoning navigation system or/and inertial navigation system (INS). IPS fuses data from many different sensors namely depth meter, Doppler velocity log (DVL), attitude and angular velocity sensors (heading, pitch and roll), global positioning system (GPS) receiver etc. The main disadvantage of INS and reckoning navigation system is performance degrading as time goes by. Hence, to guarantee long-term stable operation of AUV it is necessary to periodically correct its coordinates by means of any drift-free positioning system. Since seawater is opaque to the radio waves, GPS can be used by AUV only for surface position fix. The modern underwater robotics is confronted with tasks, demanding not only accuracy but also high mobility and cost effectiveness from underwater robotic system. Among these are search and inspection of stretched objects (e.g. pipe lines, cables etc.), ecological monitoring and many other underwater investigations.
