  Motivated by real-world applications of unmanned aerial vehicles, this paper
introduces a decentralized control mechanism to guide steering control of
autonomous agents maneuvering in the vicinity of multiple moving entities (e.g.
other autonomous agents) and stationary entities (e.g. fixed beacons or points
of references) in a three-dimensional environment. The proposed control law,
which can be perceived as a modification of the three-dimensional constant
bearing (CB) pursuit law, provides a means to allocate simultaneous attention
to multiple entities. We investigate the behavior of the closed-loop dynamics
for a system with one agent referencing two beacons, as well as a two-agent
mutual pursuit system wherein each agent employs the beacon-referenced CB
pursuit law with regards to the other agent and a stationary beacon. Under
certain assumptions on the associated control parameters, we demonstrate that
this problem admits circling equilibria with agents moving on circular orbits
with a common radius, in planes perpendicular to a common axis passing through
the beacons. As the common radius and distances from the beacon are determined
by the choice of parameters in the pursuit law, this approach provides a means
to engineer desired formations in a 3-dimensional setting.
