A framework for a hierarchical model of cooperation between unmanned airplanes

In this article we propose a framework for a hierarchical model for cooperation between unmanned airplanes in large groups. We argue that the swarm approach to cooperation between a large number of mobile robots is ineffective when robots can be equipped with efficient communication, precise location hardware and with complex control algorithms. The proposed model, analogous to the organisation of a team of people, is an intermediate solution, between the swarm approach and central control. The bottom layer of the model includes unmanned airplanes that perform tasks related to the mission goals, such as capturing images, looking for objects through image analysis, etc. These airplanes are organised in teams, and each team is controlled by the superior airplane. Two top layers are ground-based: the central computer and the human operator, and their functions are mostly defining the goals, planning and optimisation of the mission. We present two examples of response to events, related to failure or loss of an airplane. We discuss how the proposed model can manage possible interruptions of communication and security issues, and how collision avoidance can be implemented. Finally, we point out that, although the control structure is different than in the swarm approach, swarm intelligence can still be used to optimise missions.