Why would a researcher build robots that look and act like bats?

Search and rescue missions often take place in areas that are difficult for humans to navigate due to extreme weather, rugged terrain, or dangerous conditions such as smoke or dust.

A researcher at Worcester Polytechnic Institute (WPI) wants to send bat-inspired robots on these tasks instead of humans.

Nitin Sanket, a professor at WPI, has developed small flying robots with his team that can fit in the palm of a hand and use ultrasound — just like bats. These robots use AI-powered software to filter out noise from ultrasound signals collected by the devices, allowing them to detect obstacles within a two-metre radius.

“Search and rescue is done on foot,” Sanket told TechCrunch. “There are a lot of people out on foot with flashlights in really harsh conditions and putting their lives on the line to save others. We thought drones were the answer because they can cover a lot of ground very quickly. They can be agile and fast.”

Sanket has always been fascinated by aerial robots and drones and how the technology can be updated to suit real-world situations. During his doctoral program, his advisor challenged him to create the smallest robot possible, which led to his research into taking cues from biology to build smaller machines.

“We had to reimagine what a drone would be at that point, which was going back to biology, because biology does that way better than we can today,” Sankett said. “How can insects or birds do this with very limited computation and not-so-good sensors? Their eyes aren’t that good, and their brains are really small, but they can still do these amazing feats of flight. So we started looking into that, and that’s what led to my doctoral thesis.”

Sanket has built a prototype of a robotic beehive made up of small drones that can pollinate flowers. Despite his efforts, he realized that this application might have been a huge success and began thinking about areas where biology-based robots could urgently make a difference, which led him to his current project.

For search and rescue robots, the main challenge was to build something that contained the necessary sensors and flight technology without making the robot too large, expensive, or power-hungry.

Sanket said they turned to ultrasonic sensors used in automatic faucets because they require very little power. While this approach worked, the propellers they made on the robots made a lot of noise, which put an increased burden on the sensor’s ability to detect obstacles.

To solve this problem, they turned to bats.

“Bats have these special tissues in their nose, ears and mouth that change thickness and density adaptively to modify the way they hear and chirp sound,” Sankett said. “We were like, ‘Okay, this is pretty cool.’ Can we do something like this? We designed a 3D-printed structure to put in front of the robot, which essentially does the same thing [functionally, as] “What the bat does is change the shape of the sound itself.”

Now that they can operate the robots, they are working on their next challenge: improving their speed.

“We, as humans, like to try to imitate a lot of the things that the human brain does,” Sankett said. “We tend to forget how amazing other animals are, which are much smaller than us. Especially insects and birds, which are much smaller, they can actually do amazing feats of navigation, which I think we don’t see very often. I think we should think more as scientists and not just pure engineers.”