A team of scientists has just built the first robot that looks and flies like a bat. They named it, of course, Bat Bot.
Bat Bot is nothing short of an engineering marvel. It weighs in at only 3.3 ounces—about as heavy of two golf balls. With a silicone membrane stretched over its carbon-fiber skeleton, a head crammed with an on-board computer and sensors, and five micro-sized motors strung along its backbone, Bat Bot is capable of autonomous, flapping flight. Designed by trio of roboticists led by Soon-Jo Chung at Caltech, it was unveiled today in the journal Science Robotics.
What makes Bat Bot so remarkable is just how damn hard it was to mimic a bat's natural flight. If flying was an art form, bats would make fixed wing-pilots looks like they're finger painting. That's because with each flap of their wings, "bats use more than 40 active and passive joints, [alongside] the flexible membranes of their wings," says Chung. In addition, bats take advantage of a whole suite of other hard-to-imitate biological tricks, such as bones that adaptively deform each wing-beat.
"Arguably, bats have the most sophisticated powered flight mechanism among animals," the roboticists write in their paper.
Bat Bot performs four main components of bat wing movement - the shoulder, elbow, and wrist bend, and the side-to-side tail swish.
To build Bat Bot, Chung's team first had to dispense with the fantasy that they could just mechanize flapping bat wings, joint by joint. "It's impractical, or impossible, to incorporate [all 40] of these joints in the robot's design," says Chung. Even with today's most advanced robotic technology, you'd just end up with a heavy, clunky robot that would never make it off the ground.
Instead, the trio pored over biological studies of bat flight, including a extremely helpful 2008 study on bat joints authored by the biologist and Discovery Channel host Dan Riskin. Scouring the studies, they sought to understand which of these 40 joints they could dispense with and which were absolutely vital.
"Arguably, bats have the most sophisticated powered flight mechanism among animals."
In the end, Chung's flying robot has a total of nine joints. And while Bat Bot is a seriously advanced piece of machinery, it is still a pretty simple bat. For example, Bat Bot's carbon-fiber "fingers" don't have knuckles or knuckle joints. And bat bot doesn't actively twist its wrists like a normal bat does.
There are other simplifications too. While bats' wing membranes can have different levels of stiffness in different places, Bat Bot's hyper-thin silicone membrane (which Chung's team built themselves) is uniformly flexible.
Nevertheless, Bat Bot's elegant flight looks almost indistinguishable from its biological cousin. It fluidly and independently tucks and extends its wrists, shoulders, elbows, and legs as it glides through the air. If you aren't a biologist, then you'll be hard pressed to spy the mechanical differences between Bat Bot's flapping and the real thing.
Even cooler, Bat Bot is not remote controlled. Leveraging a lightweight suite of sensors and computers, it can autonomously perform a flapping glide, bank turns, and sharp dives. But Bat Bot is not perfect—yet. It can't yet ascend in the air; it can only flap its way through a controlled glide. Escalating flight, as well as a bat's quintessential upside-down perch, are two capabilities Chung's team is working on right now.
Rousettus aegyptiacus's flight characteristics inspired those of Bat Bot.
Bat Bot's sheer complexity makes you wonder: Why wrangle with the complex and fickle flight of bats in the first place when we already have nimble flying robots on the market, such as those drone quadcopters?
Chung's team argues that Bat Bot's softness and lack of rapid-spinning propellers make it safer around humans than other flying robots. Chung imagines that future incarnations of Bat Bot could fly about new building sites mid-construction, perching on beams to snap photos, or to spy mistakes or other structural flaws. If one bumps into a construction worker, no problem.
Having once taken a rogue quadcopter to the face, I can attest to their assertion that propeller-to-forehead impact with humans is really painful and should be avoided at all cost.
Perhaps it would be easier just to build a safer quadcopter. But hey, we're not here to question this plucky robot. Bat Bot's raison d'être is even more straightforward. First, Bat Bot is awesome. Second, we figure Bat Bot is highly effective nightmare fuel for those already afraid of bats, and what's not to love about that?