Engineering news
Engineers from Harvard University have created miniature robots, nicknamed RoboBees, that are able to land and perch on surfaces, rather than hover, in order to conserve energy.
Moritz Graule, first author of the paper and student at Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), said the research will help to create small drones that are able to stay in the air for extended periods of time without the need for too much additional energy.
"A lot of different animals use perching to conserve energy," said Kevin Ma, co-author of the paper. "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."
Instead, the team turned to electrostatic adhesion - the same basic science that causes a static-charged balloon to stick to a wall.
When you rub a balloon on a wool jumper, the balloon becomes negatively charged. If the charged balloon is brought close to a wall, that negative charge forces some of the wall's electrons away, leaving the surface positively charged. The attraction between opposite charges then causes the balloon to stick to the wall.
"In the case of the balloon, however, the charges dissipate over time, and the balloon will eventually fall down," said Graule. "In our system, a small amount of energy is constantly supplied to maintain the attraction."
The RoboBee, created at the Harvard Microrobotics Lab, uses an electrode patch and a foam mount that absorbs shock. The entire mechanism weighs 13.4mg, bringing the total weight of the robot to about 100mg - similar to the weight of a real bee. When the electrode patch is supplied with a charge, the robot 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, offering to dramatically extend the operational life of the robot. Reducing the robot's power requirements is critical for the researchers, as they work to integrate on-board batteries on untethered RoboBees.
Currently 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.
"There are more challenges to making a robust, robotic landing system but this experimental result demonstrates a very versatile solution to the problem of keeping flying microrobots operating longer without quickly draining power," said Ma.