Achieving variable formation shapes for sweep operations using rendezvous cones

Abstract

This paper proposes guidance laws to achieve and maintain different shapes of formations of UAVs in order to perform efficient sweep operations. Such sweep operations need to be performed for applications such as surveillance, crop spraying, cloud seeding, etc. While performing such sweep operations, the relative positioning of the UAVs needs to be such that neighboring UAVs are close enough to ensure that they are able to communicate with each other, while also maintaining the shape of the formation. This paper assumes that the communication region of each UAV is not necessarily omni-directional. Such anisotropic communication regions can occur when the UAVs use directional (beam-forming) antennas for communication purposes. This paper facilitates sweep operations in such scenarios by developing guidance laws that guide a UAV into the communication footprint of another UAV, when the communication footprint is more elongated in one direction compared to other directions. In order to achieve this, the concept of a rendezvous cone is used. The rendezvous cone of a UAV represents the set of its velocity directions that will lead the UAV on a path to rendezvous with (that is, move into the communication footprint of) another UAV. The rendezvous cone is used to determine nonlinear analytical guidance laws that enable multiple UAVs to come together to achieve a formation prior to performing a sweep, and additionally, enable changes in the formation shape while the sweep is being performed.