Linear motion observers for ASC/AUV tandems based on single range readings

This paper proposes novel cooperative navigation strategies for an Intervention Autonomous Underwater Vehicle (I-AUV) working in tandem with an Autonomous Surface Craft (ASC). The proposed solutions rely on single range readings and two different scenarios are considered: in the first, the I-AUV is assumed to be moving in the presence of unknown constant ocean currents and the ASC transmits its inertial position and velocity, while the I-AUV measures its velocity relative to the water; in the second case, the ASC transmits its inertial position and the I-AUV is assumed to measure its velocity relative to the ASC. Necessary and sufficient observability conditions are derived for both problems and globally asymptotically stable (GAS) filters are developed. Although inspired in marine robotics, the proposed methods apply to other mobile platforms as they are based on the general motion kinematics in 3-D. Finally, to assess the performance of the proposed solutions, realistic simulation results are presented and discussed.