In 2013, a Carnegie Mellon University team called “Epiphany” released a small game on the Ouya, an Android-based micro-console developed via Kickstarter.
They called their game “It Takes Two,” and in it, a circle and a square must maneuver through their world while tethered together. The players could choose to hinder the other or cooperate as they solved various challenges.
Well, researchers are doing something similar, but they’re using robots rather than video game shapes.
Princeton engineers paired small robot toys with a flexible tether, with amazing results. The bots explored enclosed spaces, easily solved mazes, and rounded loose objects into patterns.
Published in the Proceedings of the National Academy of Sciences, the researchers found that connecting the robots with a flexible polymer tether enabled them to exhibit morphological computation, where physical characteristics, rather than digital calculation, can be harnessed to solve complex problems.
There are applications outside of toys. For example, scientists are trying to control swarms of robots for everything from surveillance systems to space exploration applications, often teaching each robot to respond to simple cues from its neighbors like a fish swimming in a school. The Princeton team wanted to explore whether it was possible to control groups of robots that lack computing power and only respond to physical input.
The toy bots are small robots called bristlebots, featuring flexible legs and a vibrating internal motor that drives their insectile motion. They lack computer control, relying on mechanical friction to direct them. The bots are used in scientific experiments to stand in for gas particles and bacteria.
A PAIR OF TETHERED BOTS SOLVES A MAZE AT PRINCETON ENGINEERING. Credit: Princeton University
The team wanted to see if they could create complex behavior without using lights or other outside instructions, leveraging mechanical intelligence to solve problems the same way a hand grasps a ball.
The answer was a flexible tether created with a 3D printer. Using cameras to track the bots, they developed mathematical models that predicted bots’ behavior based on variables including the bot force and the tether’s length and flexibility. They attached a tether to the front edge of each rectangular microbot. As they increased the polyester’s flexibility, the tethers began to buckle as the bots pushed, buckling into a U-shaped curve. The tether connecting the bots controlled the pair’s direction by preventing either from skittering in a random direction. They then calculated the angle that allowed the bots to move forward in a controlled direction with the greatest speed.
The researchers moved on to obstacles and found that when running into a wall, the U-shaped tether flattens, causing one of the paired bots to scoot along the wall. Eventually, the curve in the tether reappears, pointing in a different direction, and the pair navigates away from the wall—key to the pair’s ability to navigate mazes.
The team also examined the bots’ ability to squeeze through openings and developed ways to use the bots to gather loose objects on a tabletop into separate groups. They will keep working on the tether system and explore other behaviors and arrangements with larger numbers of tethered bots and drones moving in three dimensions.
While Epiphany’s “It Takes Two” is no longer available on the Ouya, you can download it for the PC from the team’s website. Look for the “Download Now” image in the carousel.
