  We present the Robotic Overlay coMmunicAtioN prOtocol (ROMANO), a
lightweight, application layer overlay communication protocol for a unified
sensing and control abstraction of a network of heterogeneous robots mainly
consisting of low power, low-compute-capable robots. ROMANO is built to work in
conjunction with the well-known MQ Telemetry Transport for Sensor Nodes
(MQTT-SN) protocol, a lightweight publish-subscribe communication protocol for
the Internet of Things and makes use its concept of "topics" to designate the
addition and deletion of communication endpoints by changing the subscriptions
of topics at each device. We also develop a portable implementation of ROMANO
for low power IEEE 802.15.4 (Zigbee) radios and deployed it on a small testbed
of commercially available, low-power, and low-compute-capable robots called
Pololu 3pi robots. Based on a thorough analysis of the protocol on the real
testbed, as a measure of throughput, we demonstrate that ROMANO can guarantee
more than a $99.5\%$ message delivery ratio for a message generation rate up to
200 messages per second. The single hop delays in ROMANO are as low as 20ms
with linear dependency on the number of robots connected. These delay numbers
concur with typical delays in 802.15.4 networks and suggest that ROMANO does
not introduce additional delays. Lastly, we implement four different
multi-robot applications to demonstrate the scalability, adaptability, ease of
integration, and reliability of ROMANO.
