Robots by the dozen are prohibitively expensive, so actually testing how large swarms would work together is often limited to computer simulations. That's where Harvard's Kilobots are beginning to bear fruit – at a cost of US$14 each in batches of a thousand, they're a tenth the cost of their cheapest competitor. At such bargain-basement prices, Michael Rubenstein, Christian Ahler, and Radhika Nagpal at the Self-Organizing Systems Research Group have begun to build their own little robot army.
A single Kilobot communicates with its neighbors by pulsing its infrared LED, which shines and reflects off the floor beneath it. Any Kilobot within 10 cm will pick up the message with an infrared photodiode receiver. They move around on their stilt-like legs by simply vibrating.
Back in 2011 when the project first came to our attention, we saw how 29 Kilobots could demonstrate some interesting collective behaviors. In one experiment, the robots acted like ants foraging for food, and in another they played follow-the-leader, effectively forming a jittery little conga line.
Now the group has published some videos where up to 100 Kilobots intermingle, a feat that would have been reserved for computer simulations just a few years ago. In the first video, the Kilobots have been programmed to seek out light using a visible light sensor on each robot.
100 Kilobots move towards a light source
In the next video, the robots' movements have been constrained by objects with different shapes, showing how the robots can work together to move large objects. They even manage to get the job done when tasked with moving a wiggling shape.
Collective transport with 100 Kilobots
You can keep an eye on future Kilobot experiments at the Self-Organizing Systems Research Group's YouTube channel.