Bradley E. Bishop and Daniel J. Stilwell
United States Naval Academy

Control Techniques for Platoons of Underwater Vehicles

In this talk, cooperating professors present methods for control of cooperating robots, consisting of two convergent methods for the control of platoons (or swarms) of cooperating autonomous underwater vehicles. The two distinct techniques that will be presented approach the problem from opposite directions, first asking what we can hope to accomplish with fully centralized control and then focusing on techniques for generating decentralized controllers that will approach the performance of a centralized scheme.

We initially cast the vehicle platoon as a redundant manipulator, allowing us to bring to bear all of the well-established tools of redundant manipulator control to assist in real-time motion planning and formation synthesis. We develop a novel technique for optimizing the null space of the platoon Jacobian function so that secondary tasks can be achieved with locally maximal system resources. This fundamentally new approach to platoon modeling allows us to build sophisticated centralized platoon behaviors based on sound control theoretic techniques without the necessity for off-line motion planning, nor even advanced computational capabilities.

We then present basic results on the use of decentralized control theory to aid in understanding how platoons of vehicles might cooperate underwater. Of fundamental importance to our work is the severely limited communications channel available underwater. We highlight a particular solution that arises from the decentralized control framework: a broadcast-only communications structure in which the total communications bandwidth is independent of the number of vehicles in the platoon.