Cooperative caging using autonomous aquatic surface vehicles

We present a study on the use of cooperative robots to execute a caging mission on the water´s surface. In particular, we consider the problem of using two robotic boats (under-actuated autonomous surface vessels) connected with a floating rope, to `capture´ a floating object from a known location on the water´s surface and ´shepherd´ it to a designated position. This paper focuses on the cooperative control strategy of the two vessels. Each vessel´s behavior is governed by a supervisor software module that handles the communication with the other vessel and controls all elementary tasks that compose the overall mission. The elementary tasks, specifically developed for under-actuated vessels, are arranged by priority, and merged using a behavior-based approach, namely the Null-Space based Behavioral control. The proposed technique is validated by field experiments with two autonomous robotic boats on the surface of a lake.