This paper describes a distributed formation control algorithm that takes into consideration some practical issues that arise from implementation (namely, the presence of input disturbances), seeking its application to multirotor vehicles. The proposed control algorithm is then validated in an indoor experimental setup.
Formation control of multi-vehicle systems is an important research topic in the coordinated motion of teams of autonomous vehicles. Moving in formation can have several advantages on the overall system, such as increased redundancy and robustness, and reduced cost . This problem presents several challenges, related not only to the lack of total information by each vehicle, but also to the desire to use a distributed, or a decentralized approach. In decentralized approaches, each agent makes its own decisions independently from the others. Therefore, a central controller, coordinator, or supervisor does not exist, making the problem more challenging. Despite the challenges, a decentralized approach is still the one that presents more potential applications, as it provides scalability and robustness to the system.
This topic has been the subject of increased interest over the past couple of decades. On one hand, this interest is driven by the wide variety of tasks that can benefit from the use of cooperative teams of vehicles, such as: i) aerial cinematography, to shoot from several perspectives, simultaneously; ii) precision agriculture, since tasks can be accomplished faster by using teams of vehicles, and iii) mapping and surveying. On the other hand, advances in technology have led to an increase in computation, sensing, actuation, and communication capabilities, allowing for the implementation of these concepts in real-world operation of large-scale systems.
An excellent survey on the topic of formation control can be found in . There, the authors distinguish the formation control approach into three main categories: position-, displacement-, and distance-based approaches. Position-based approaches consider that each vehicle measures its absolute state and therefore can take its position in the formation, without the need to interact with other vehicles. Although simple, this approach is the most demanding with respect to the sensing capabilities of each vehicle. Displacement-based approaches, studied for example in  and , consider that the agents can only measure relative quantities (e.g., measurement of the relative position, or displacement, to another agent), and that they have the same sense of orientation. However, it is necessary to have more interactions between agents, in order to overcome the reduced sensing capability. Finally, distance-based approaches, studied for example in , assume that agents only have access to relative measurements and moreover do not share a sense of orientation. Therefore, formations are stabilized based only on interagent distances, not accounting for orientation. This approach is the less demanding in terms of sensing capability of the agents. However, it requires more interactions between the agents and the use of more elaborate control laws.
Orientadores: Rita Cunha e Pedro Batista
Institute for Systems and Robotics, LARSyS, Instituto Superior Técnico, Universidade de Lisboa, Portugal
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