Even the most intelligent robot is useless without power.
While advanced robots like Honda’s Asimo regularly astonish audiences with their dexterity, the power-hungry humanoid needs a change of battery after only 40 minutes.
For future robots to perform useful tasks, such as undertaking construction work or exploring disaster zones, they will need smarter ways to keep their batteries topped up when they are out of reach of a mains-powered battery charger, or an obliging human.
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“No robot can be truly autonomous if it cannot revive itself after its battery has expired,” says Trung Dung Ngo, a robotics researcher at Aalborg University in Denmark. Too much research, he says, is directed at giving robots behavioural autonomy, instead of energy autonomy. “They must have a means to self-power,” he says.
So Ngo and his colleague Henrik Schioler have come up with a plan whereby a sizeable “mother ship” robot will continually replace and charge up batteries for swarms of smaller robots. It does this using its own very large battery, supplemented by solar or fuel cells.
The fully charged small robots leave the mother ship and go off to perform their programmed tasks. Then, as their batteries begin to run low, they send out a wireless distress call to the mother ship and all the other robots (Advanced Robotic Systems International, vol 3, p 313).
If the mother ship can reach the flagging robot, it will donate a charged battery from its store of spares in exchange for the dying one. It then charges up the old battery ready for reuse by another robot. But if the smaller robots are out of reach, searching under the rubble of a destroyed building or inspecting an enclosed area for example, Ngo envisages them deciding among themselves who has the most power to spare and donating one of its spares, so that each has enough power to go back to the mother ship for fresh batteries. This allows the robots to complete complex tasks without having to waste time recharging.
Ngo has built a prototype swarm of four robots and a mother ship, and says his idea works. He hopes to test the idea on a much larger scale.
“It’s an important area they are addressing here,” says Chris Melhuish of the Bristol Robotics Laboratory in the UK, whose team is developing EcoBot, a robot that gets energy by eating dead flies. “And it’s one that will get more important as we develop more applications where robots have to get out and do their own thing.”
