Researchers at Georgia Tech and Duke University have created a wirelessly powered robot swarm. Their demo robot swarm consists of five robots performing a line following task, each consuming 200mW. The fundamental design looks quite straight-forward, relying on a robot arena surface equipped with a transmit coil and robots with a receiving coil positioned between their wheel base close to the ground.
A circulating current in the transmit coil generates a magnetic flux which transfers power to the robots via inductive-coupling. The technology is great news for people working with swarms of dozens or hundreds of robots which currently require laborous connection and deconnection to charging stations. Details of the setup used, including a detailed description and circuit diagrams, are available online
Links:Surface Based Wireless Power Transmission and Bidirectional Communication for Autonomous Robot Swarms (PDF)Video