In the GIF below, we see Bluebots trying another task: a search mission. This behavior is a bit more complicated, guided by a few separate guidelines in the algorithm. The first step is known as distribution; the algorithm guides the robots to keep away from each other. It scatters them in search of their target, a red LED at the bottom of the tank. “If everyone spreads and maximizes their distances, they get better coverage, and the chances of them finding the source increase,” Berlinger says.
When one Bluebot stumbles upon the red LED, it starts flashing its own blue LEDs, a sign to its comrades that it has found the target. When another robot sees the blue flashing, its algorithm switches from the distribution guideline to an aggregation guideline that collects the robots around the target. “Once they see the source themselves, they also start flashing their LEDs to amplify the signal,” says Berlinger. ‘Parallel actions can greatly accelerate that search mission. If a single robot had to search for the source, it would take about ten times as long as the seven robots. ‘
This is the power of the crowd: A team of Bluebots in constant communication – and an extremely simple form of communication – can work together to accomplish a mission. “I find it an extremely challenging problem to do these experiments,” says roboticist Robert Katzschmann of the research university ETH Zurich, who developed his own robotic fish but was not involved in this new research. “So I’m very impressed with the fact that they set it up, because it looks a lot easier than it actually is.”
“Now,” Katzschmann adds, “the question is, do real fish really do it this way?” Vision is certainly an important tool for teaching fish, but like other animals, their perception is ‘multimodal’. That is, their vision works in conjunction with their other senses, in this case a fish organ known as the lateral line. This series of sensory cells, running from head to tail along a fish’s side, detects subtle changes in water pressure, which can complement the vision to keep it in sync with its peers as the school moves around.
However, it is clear that these researchers achieved impressive complex swarming behaviors with vision alone. And as cameras become cheaper and more sophisticated, it will enable researchers to give their Bluebots a better picture of their environment. “I really want to get rid of the blue LEDs and literally just have patterns on the fish and be able to do more,” says Harvard robot Radhika Nagpal, a co-author on the page. Perhaps the Bluebot will one day be able to hit the open sea, where it must visually detect obstacles such as coral so as not to crash. It can even search for invasive species such as the lionfish by searching for its distinctive shaped morphology, as it has not yet developed LEDs to guide the Bluebot.