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“Hated in the Nation,” an episode of Netflix’s dystopian sci-fi series “Black Mirror,” predicted it: Thousands of robotic bees buzz from flower to flower, pollinating plants to make up for declining insect populations. And while the episode’s robots eventually turn against their human inventors, killing over 387,000 people by ramming their artificial stingers into victims’ heads, the MIT scientists working on perfecting today’s aerial robots likely believe we don’t need to worry about that.
Well, for now.
Despite the show’s foreboding take on robotic bees, researchers at the Massachusetts Institute of Technology are one step closer to perfecting the artificial aerial critters. In a paper published March 15, a group of researchers at MIT showed that using resilient muscle-like actuators and self-repairing technology can vastly improve the robustness of robotic bees.
“Insects flying are incredibly difficult to understand,” said Kevin Chen, an assistant professor at MIT, head of the institute’s Soft and Micro Robotics Laboratory, and the senior author of the paper. “The aerodynamic principles that insects use are very different than, for example, airplanes or other flying objects. So trying to build a scale flying robot definitely gives us tools to understand the insects.”
Historically, Chen says, research has focused on how to perfect flight controllability and collision prevention for flying robots. But he says this emphasis on controllability is unlike what we see in nature, as bees bump into things all the time and can continue to fly. In fact, studies show that bees can lose up to 40% of their wings and continue to buzz through the air: It’s their ability to continue flight after taking hits and bumps that makes them such resilient flyers.
So the MIT researchers sought to emulate that resiliency, looking for ways to repair and recover the flying robots after puncturing the wings.
The mix of graduate students and professors turned to a type of soft artificial muscle, called dielectric elastomer actuators (DEAs), that can withstand punctures and bumps, continuing to flap the robot’s wings. The muscle-like material is made from layers of elastomer stuffed between electrodes. And when met with voltage, the electrodes squeeze the elastomer, rapidly flapping the wings.
“The unique aspect about our robot is the actuators are soft. They’re sort of soft artificial muscles,” Chen said. “And if you look at a … video of the robot operating, the soft artificial muscle shrinks and elongates … very similar to muscles. And the main contribution of the … work published last week was trying to incorporate [a] similar level of robustness into those artificial muscles.”
Using the DEAs, the scientists then performed two types of robustness tests — damaging the wings with minor and major punctures, or injuries. When the elastomer received a minor injury, using the voltage used to power the wings, the robot engages in a process called self clearing. Essentially, when presented with a small defect, the voltage burns out and disconnects the local electrode near the defect, isolating it from the rest of the robot. And because of this, the rest of the robot continues to function as normal.
When presented with a major injury — a larger puncture that allows air into the robot — the researchers used a laser to surgically remove the defect. This isolated the larger defect, leaving only a minor injury that could then be isolated by the self clearing process.
“You have a major point of damage, then use the laser to cut around that damage. So effectively … the laser creates a minor injury that surrounds the major injury. And the minor injury can be auto-healed … [and] isolated from the rest of the actuator,” Chen said. “So the idea is that then the minor injury isolates the major injury and then the minor injury isolates themselves, which is equivalent to isolating the major injury. So in some sense, we use the analogy of using a laser to perform a small surgery on the soft artificial muscle.”
To actually see if the robots had improved resilience, the researchers used two types of tests. One incorporated electroluminescent particles into the actuator, which only light up if the specific part of the actuator is functioning. The other was to see if the robot could fly. And because of the soft, muscular actuator, along with its self clearing isolating process, the damaged bees took flight at levels incredibly similar to the undamaged ones.
Chen says this work, specifically the resilient muscle-like actuator, can be used in the future for robots flying in tight spaces where they will likely be damaged. And that it can be used in various types of robotic applications like jumping robots, and even for cleaning oceans.
“We are looking for not only incorporating these artificial muscles in a robot, but a wide range of other robotic systems,” Chen said. “Our longer term goal is to really create artificial muscle that behaves and feels exactly like muscles.”
But at least from an art-reflects-life standpoint, let’s just hope that when the actuator is incorporated into bees, that they aren’t too resilient.
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