Distributed formation control of 6-DOF autonomous underwater vehicles networked by sampled-data information under directed topology

In this paper, a sampled-data networking strategy is investigated for the formation problem of multiple 6-DOF autonomous underwater vehicles (AUVs) in the presence of external disturbances. Unlike the common condition in most literatures associated with multiple vehicles, where the information is assumed to be exchanged continuously, in our proposed strategy, the position and orientation information of the multiple AUVs is exchanged according to a discrete-time sequence, which is more applicable to current technologies for underwater communications. More precisely, this strategy can be modeled by a sample-and-hold mechanism and is capable of both uniform and non-uniform sampling cases. In particular, it has a potential advantage from an energy perspective, since communication reduction always leads to less energy consumption. By model transformation, distributed controllers are designed based on input-to-state stability (ISS) property to ensure that both configuration formation and rendezvous-type formation can be achieved. An optimization procedure is also presented to calculate the maximum allowable sampling period. Finally, a numerical example is provided to illustrate the effectiveness and applicability of the theoretical results.