  Swarms of autonomous surface vehicles equipped with environmental sensors and
decentralized communications bring a new wave of attractive possibilities for
the monitoring of dynamic features in oceans and other waterbodies. However, a
key challenge in swarm robotics design is the efficient collective operation of
heterogeneous systems. We present both theoretical analysis and field
experiments on the responsiveness in dynamic area coverage of a collective of
22 autonomous buoys, where 4 units are upgraded to a new design that allows
them to move 80\% faster than the rest. This system is able to react on
timescales of the minute to changes in areas on the order of a few thousand
square meters. We have observed that this partial upgrade of the system
significantly increases its average responsiveness, without necessarily
improving the spatial uniformity of the deployment. These experiments show that
the autonomous buoy designs and the cooperative control rule described in this
work provide an efficient, flexible, and scalable solution for the pervasive
and persistent monitoring of water environments.
