"Many applications for small drones require them to stay in the air for extended periods," explained Moritz Graule, researcher at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering at Harvard University. "Unfortunately, smaller drones run out of energy quickly. We want to keep them aloft longer without requiring too much additional energy."
The team found inspiration in nature and simple science.
"A lot of different animals use perching to conserve energy," said Kevin Ma, Ph.D., postdoctoral researcher at SEAS and the Wyss Institute. "But the methods they use to perch, like sticky adhesives or latching with talons, are inappropriate for a paperclip-size microrobot, as they either require intricate systems with moving parts or high forces for detachment."
The RoboBee has been updated to include an electrode patch and a foam mount that absorbs shock. When the electrode patch is supplied with a charge, it can stick to almost any surface, from glass to wood to a leaf. To detach, the power supply is simply switched off.
"One of the biggest advantages of this system is that it doesn’t cause destabilising forces during disengagement, which is crucial for a robot as small and delicate as ours," said Graule.
The patch requires about 1000 times less power to perch than it does to hover, dramatically extending the operational life of the robot. Reducing the robot’s power requirements is critical for the researchers, as they work to integrate onboard batteries on untethered RoboBees.
"The use of adhesives that are controllable without complex physical mechanisms, are low power, and can adhere to a large array of surfaces is perfect for robots that are agile yet have limited payload — like the RoboBee," added Robert Wood, Ph.D., Professor of Engineering and Applied Sciences at SEAS. "When making robots the size of insects, simplicity and low power are always key constraints."
Right now, the RoboBee can only perch under overhangs and on ceilings, as the electrostatic patch is attached to the top of the vehicle. Next, the team hopes to change the mechanical design so that the robot can perch on any surface.
