Advancing artificial animals

technology feature Robot meets real. Credit: Illustration: E. Dewalt / Springer Nature; background image: Getty Advancing artificial animals A human can’t easily infiltrate another species’ social group to examine and influence what makes the animals tick. But the right robot can open up a clever way in. Alla Katsnelson W hen Maurizio Porfiri set out a decade ago to build a robot that could control how a group of animals behaved, he envisioned using it in the wild to perform environmental functions such as steering fish away from danger. “If there was an oil spill or a natural disaster, then you could use the robot as kind of a sheepdog for driving the fish away from the polluted region,” he says. His team first embarked on the project from a distinctly engineering point of view—what they cared about was whether or not the fish could be directed from one place to another by the robotic device. But their interest soon veered in a more philosophical direction. “As we were doing the experiments, we got interested in what’s going on in their heads,” says Porfiri, a mechanical engineer at New York University Tandon School of Engineering. “How do they perceive the mimicry of the robot? How do they respond to it? And, does their response depend on their personality?” These are the questions Porfiri investigates today with zebrafish, his species of choice, and a workshop for building any manner of robotic rig. He and a handful of other researchers working at the intersection of biology and robotics are exploring the intriguing possibilities and the inherent challenges of creating robot versions of animals that can interact with their flesh and blood counterparts. There’s a lot to be learned from letting robots loose in a group of behaving animals. For one thing, to understand animal behavior—be it directional decision-making in fish, communication in honeybees, or shelter-seeking in cockroaches—researchers implicitly or explicitly create a conceptual model of it. Recreating that behavior in a robot through cues convincing enough that the robot is accepted by its unmechanized peers provides a way of validating that model, says JoséHalloy, professor of physics at the UniversitéParis Diderot, who has built robotic cockroaches, chicks, and now zebrafish. Such robots allow researchers to probe animals’ reactions to different variables in highly standardized ways. For example, it can be tough to tease out how an animal’s size affects how it interacts with its conspecifics, notes Porfiri, since size is usually accompanied by other factors such Lab Animal | VOL 47 | AUGUST 2018 | 201–204 | www.nature.com/laban as age and fitness, which can in turn affect behavior. “With a robot, you can keep everything the same, and just change the size.” Engineering robotic interlopers that can have sustained social interactions with their target organisms isn’t easy, however. “At the end of the day it has to be accepted by the animal,” says Halloy. Invariably, researchers encounter limitations—often unexpected ones—in biological knowledge. Which specific cues would make the artificial creatures most realistic to the real ones? What kinds of information should be programmed in the algorithms that would allow the robots to dynamically interact with the animals? Then there are the seemingly more mundane issues: Can the programs that ensure the robot doesn’t bump into animals, or the walls of a testing space, run in parallel with those that govern its higherorder interactions? Will the hum of the motor be too loud? Follow the cues Animal-inspired design has long been a theme in robotics, but much of it involves creating robots for human use—or simply 201 technology feature for human fascination. Think the fantastical creations of the companies Boston Dynamics and Festo, mimicking everything from ants, fleas and spiders to dogs, cheetahs and kangaroos. Since about the early 1990s, researches have also designed robots that mimic features of specific animals in order to investigate how they perform certain behaviors. For example, bioroboticist Barbara Webb at the University of Edinburgh creates robotic insects to study complex behaviors, such as how ants navigate. Auke Ijspeert, at the Swiss Federal Institute of Technology in Lausanne, uses robotic salamanders to explore how the modeled animal’s neural circuitry supported its evolutionary shift from aquatic to terrestrial locomotion. But only in the last decade have researchers begun to study how animals interact with robotic versions of themselves. One root of such efforts stretches decades back to ethologists such as Nikolaas Tinbergen, who shared the 1973 Nobel Prize in Physiology or Medicine for showing he could elicit instinctual behaviors, such as fighting, from fish using wooden dummies that carried species-specific cues. That work revealed that artificial animals could trick the real ones into interacting with them if they conveyed the right signals. Robotics, however, opens another dimension because the possibilities for interaction can go both ways and are significantly more complex. In 2007, Halloy and his colleagues created cockroach robots that could integrate into a Waggle and roll: Tim Landgraf's robotic bees don't need to look like an actual bee to perform a convincing waggle dance. Credit: T. Landgraf, Free University Berlin 202 The robots and the bees: Evolutionary algorithms can learn from the animals, and encourage specific behaviors. Credit: EU FET project ASSISIbf (project coordinator: T. Schmickl) social group of real roaches and influence its dynamics1. Cockroaches aren’t very visual, so their mechanized brethren didn’t have to look like them. Instead, the researchers made a concoction of chemicals that Halloy calls Cockroach Chanel #5, essentially rebuilding the olfactory cue through which cockroaches communicate. Cockroaches tend to scurry out of the light, so the team created two shelters in a well-lit enclosed space, one invitingly dark and the other a bit brighter. When the natural roaches and their four robot relatives were first released into the enclosure, group social dynamics prevailed and both gravitated to the darker shelter. But when the robo-roaches were programmed to prefer the lighter shelters, they could lure the insects to follow them there. The robots allowed the researchers to test their understanding of the animals’ behavior by pushing it into a direction that wouldn’t naturally arise, Halloy says. Animal-robot encounters in the lab can also reveal gaps in researchers’ understanding of behaviors, says Tim Landgraf, who heads the Biorobotics Lab at Free University Berlin. About a decade ago, Landgraf set out to create a robot that could communicate with honeybees using the waggle dance, a form of encoded communication these pollinators use to tell their hive-mates the distance and the location of forage sites. The waggle dance has been studied for decades; indeed, Austrian ethologist Karl von F (...truncated)