Servo - December 2016

SWARMS FOLDING One of the biggest challenges with swarms of robots is manufacturing and deploying the swarm itself.

Even if the robots are relatively small and simple, you’re still dealing with a whole bunch of them, and every step in building the robots or letting them loose is multiplied over the entire number of bots in the swarm. If you’ve got more than a few robots to handle, it starts to get crazy.

The dream for swarm robotics is to be able to do away with all of that, and just push a button and have your swarm somehow magically appear. We’re not quite there yet, but getting awful close.

Researchers from the Wyss Institute for Biologically Inspired Engineering at Harvard presented a paper recently demonstrating an autonomous collective robotic swarm that can be manufactured in a single flat composite sheet. On command, they’ll rip themselves apart from each other, fold themselves up into origami structures, and head off on a mission en masse.

The sheet itself consists of six layers, which are all automatically laser machined. A pre-stretched polystyrene (or PSPS) layer (a kind of shape-memory polymer) is in the center, sandwiched between layers of copper circuits etched into polyimide sheets, with paper substrates for support. The PSPS is where the magic happens.

When heated above 100°C (which can be done by running a 2. 5 ampere current through the copper circuitry), it shrinks, which is what powers the robot’s self-folding behaviors.

Otherwise, each robot consists of some discrete electrical components that have to be placed by hand, but according to co-author, Michael Tolley, “We foresee straightforward ways to automate these steps.” Self-folding robots that use shape-memory polymers have been done before, but the challenge with them is to accurately control the folding. To address that issue, the The final thing that sets these self-folding bots apart is their ability to go from a single continuous sheet to a swarm of discrete robots. Self-folding joints that are designed to prevent folding causes the PSPS to instead rip itself apart allowing each robot to split off by itself, where its vibration motors can help it buzz along flat surfaces seeking sources of light.