Cooperative control of multiple surface vessels in the presence of ocean currents and parametric model uncertainty

Abstract

SUMMARYThis paper addresses the problem of cooperative path-following of multiple autonomous vehicles. Stated briefly, the problem consists of steering a group of vehicles along specified paths while keeping a desired spatial formation. For a given class of autonomous surface vessels, it is shown how Lyapunov-based techniques and graph theory can be brought together to design a decentralized control structure, where the vehicle dynamics and the constraints imposed by the topology of the inter-vehicle communication network are explicitly taken into account. To achieve path-following for each vehicle, a nonlinear adaptive controller is designed that yields convergence of the trajectories of the closed-loop system to the path in the presence of constant unknown ocean currents and parametric model uncertainty. The controller derived implicitly compensates for the effect of the ocean current without the need for direct measurements of its velocity. Vehicle cooperation is achieved by adjusting the speed of each vehicle along its path according to information exchanged on the positions of a subset of the other vehicles, as determined by the communication topology adopted. Global stability and convergence of the closed-loop system are guaranteed. Illustrative examples are presented and discussed.

On mixed-initiative planning and control for Autonomous underwater vehicles

“…Recent work [12] shows more interest along similar lines. Multi-vehicle planning in the oceanographic context has continued to revolve along waypoint based low-level control [13]. Multiple glider deployments [14] have also been demonstrated, again using simple waypoint-based methods.…”

Relaxing the planar assumption: 3D state estimation for an autonomous surface vessel

“…Fossen [2011] presents a comprehensive point-mass model for surface vessels, which is adopted both in our approach and in the aforementioned 2D approaches. Some works mention the use of commercial state estimation devices on ASVs [Subramanian et al, 2006, Neal et al, 2012, Almeida et al, 2010, which produce attitude estimates. However, it is not clear what the measured quantities are, and only little information on the performance of such solutions is provided.…”

Artificial Neural Networks in Coordinated Control of Multiple Hovercrafts with Unmodeled Terms

“…In [13], a cooperative path following methodology was proposed under the assumption that the communication among a group of fully-actuated surface vehicles is undirected and continuous. A coordinated path following with a switching communication topology was designed in [14], while a null-space-based behavioral control technique was proposed in [15,16].…”