  A group of cooperative aerial robots can be deployed to efficiently patrol a
terrain, in which each robot flies around an assigned area and shares
information with the neighbors periodically in order to protect or supervise
it. To ensure robustness, previous works on these synchronized systems propose
sending a robot to the neighboring area in case it detects a failure. In order
to deal with unpredictability and to improve on the efficiency in the
deterministic patrolling scheme, this paper proposes random strategies to cover
the areas distributed among the agents. First, a theoretical study of the
stochastic process is addressed in this paper for two metrics: the \emph{idle
time}, the expected time between two consecutive observations of any point of
the terrain and the \emph{isolation time}, the expected time that a robot is
without communication with any other robot. After that, the random strategies
are experimentally compared with the deterministic strategy adding another
metric: the \emph{broadcast time}, the expected time elapsed from the moment a
robot emits a message until it is received by all the other robots of the team.
The simulations show that theoretical results are in good agreement with the
simulations and the random strategies outperform the behavior obtained with the
deterministic protocol proposed in the literature.
