The RoboBee, pioneered at the Harvard Microrobotics Lab, uses an electrode patch and a foam mount that absorbs shock. The entire mechanism weighs 13.4 mg, bringing the total weight of the robot to about 100mg — similar to the weight of a real bee. The robot takes off and flies normally. 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. Credit: Harvard Microrobotics Lab/Harvard University
New system extends the lives of flying microrobots. Call them the RoboBats. In a recent article in Science, Harvard roboticists demonstrate that their flying microrobots, nicknamed RoboBees, can now perch during flight to save energy – like bats, birds or butterflies. “Many applications for small drones require them to stay in the air for extended periods,” said Moritz Graule. “Unfortunately, smaller drones run out of energy quickly. We want to keep them aloft longer without requiring too much additional energy.”
“A lot of different animals use perching to conserve energy,” said Kevin Ma. “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.
When you rub a balloon on a wool sweater, 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, pioneered at the Harvard Microrobotics Lab, uses an electrode patch and a foam mount that absorbs shock. The entire mechanism weighs 13.4 mg, bringing the total weight of the robot to about 100mg – similar to the weight of a real bee. The robot takes off and flies normally. 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 destabilizing forces during disengagement, which is crucial for a robot as small and delicate as ours,” said Graule.
The patch requires about 1000X 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 onboard batteries on untethered RoboBees. 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.
“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.
Video: https://www.youtube.com/watch?v=GJecMPiEGuA https://www.seas.harvard.edu/news/2016/05/using-static-electricity-robobees-can-land-and-stick-to-surfaces
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