Shepherd: a portable testbed for the batteryless IoT

Collaboration of batteryless nodes is essential to their success in replacing traditional battery-based systems. Energy-harvesting sensor nodes experience spatio-temporal fluctuations of energy availability. These fluctuations become especially critical when sensor nodes do not have sufficient energy storage to compensate for them. Understanding the challenges and opportunities of operating groups of batteryless sensor nodes requires to record and reproduce spatio-temporal characteristics of real energy environments. We thus present Shepherd, a testbed for the batteryless IoT. Shepherd allows to record synchronized energy traces with a resolution of 3 μA and 50μV at a rate of 100 kHz, and to faithfully replay these traces to any number of sensor nodes to study their behavior. We release Shepherd as an open-source tool for the community, facilitating research into time synchronization, wireless networking, and other distributed algorithms for batteryless systems.