Bats have long captured the imaginations of scientists and engineers
with their unrivaled agility, but their complex wing motions pose
significant technological challenges for those seeking to recreate
their flight in a robot.
Chung, associate professor of aerospace and Bren Scholar at Caltech,
holds the Bat Bot.
The key flight mechanisms of bats now have been recreated with
unprecedented fidelity in the Bat Bot—a self-contained robotic bat
with soft, articulated wings, developed by researchers at Caltech
and the University of Illinois at Urbana-Champaign (UIUC).
"This robot design will help us build safer and more efficient
flying robots, and also give us more insight into the way bats fly,"
says Soon-Jo Chung, associate professor of aerospace and Bren
Scholar in the Division of Engineering and Applied Science at
Caltech, and Jet Propulsion Laboratory research scientist. (Caltech
manages JPL for NASA.)
Chung, who joined the Caltech faculty in August 2016, developed the
robotic bat, along with his former postdoctoral associate Alireza
Ramezani from UIUC and Seth Hutchinson, a professor of electrical
and computer engineering at the UIUC and Ramezani's co-advisor.
Chung is the corresponding author of a paper describing the bat that
was published on February 1 in Science Robotics, the newest member
of the Science family of journals published by the American
Association for the Advancement of Science.
The Bat Bot weighs only 93 grams and is shaped like a bat with a
roughly one-foot wingspan. It is capable of altering its wing shape
by flexing, extending, and twisting at its shoulders, elbows,
wrists, and legs. Arguably, bats have the most sophisticated powered
flight mechanism among animals, which includes wings that have the
capability of changing shape. Their flight mechanism involves
several different types of joints that interlock the bones and
muscles to one another, creating a musculoskeletal system that is
capable of movement in more than 40 rotational directions.
"Our work demonstrates one of the most advanced designs to date of a
self-contained flapping-winged aerial robot with bat morphology that
is able to perform autonomous flight," Ramezani says.
One of the key challenges was to create wings that change shape
while flapping, the way a biological bat's do. Conventional
lightweight fabrics, like nylon and Mylar, are not stretchable
enough. Instead, the researchers developed a custom ultra-thin (56
microns), silicone-based membrane that simulates stretchable, thin
aerial robots have the potential to be significantly more energy
efficient than current flying robots because their flexible wings
amplify the motion of the robot's actuators. When a bat—or the Bat
Bot—flaps its wings, the wing membranes fill up with air and deform.
At the end of the wings' downward flapping motion, the membranes
snap back to their usual shape and blast out the air, creating a
huge amplification in power for the flap.
The design has potential applications for environments where more
traditional quadrotor drones—which have four spinning rotors—could
collide into objects or people, causing damage or injury.
The study is titled "A Biomimetic Robotic Platform to Study Flight
Specializations of Bats." This research was funded by the National
Science Foundation's National Robotics Initiative.