After more than a decade of development, Harvard’s insect-sized flying robot, RoboBee, has successfully learned to land using dragonfly-inspired legs and improved flight controls. The researchers see RoboBee as a potential substitute for endangered bees, assisting in the pollination of plants. From a report: RoboBee is a micro flying robot that Harvard has been developing since 2013. As the name suggests, it is the size of a bee, capable of flying like a bee and hovering in mid-air. Its wings are 3 cm long and it weighs only 0.08 g. The weight was reduced by using light piezoelectric elements instead of motors. Piezoelectric elements change shape when an electric current flows through them. The researchers were able to make RoboBee flap its wings 120 times per second by turning the current on and off, which is similar to actual insects.
While RoboBee exhibited flight capabilities comparable to those of a bee, the real problem was landing. Being too light and having short wings, it could not withstand the air turbulence generated during landing. It is easy to understand if you think about the strong winds generated when a helicopter approaches the ground. Christian Chan, a graduate student at Harvard who participated in the research, said, “Until now, it was a matter of shutting off the robot while it attempted to land and praying for a proper touchdown.”
To ensure RoboBee’s safe landing, it was important to dissipate energy just before touchdown. Hyun Nak-Seung, a professor at Purdue University who participated in the development of RoboBee, explained, “For any flying object, the success of landing depends on minimizing speed just before impact and rapidly dissipating energy afterward. Even for tiny flapping like RoboBee’s, the ground effect cannot be ignored, and after landing, the risk of bouncing or rolling makes the situation more complex.” The findings have been published in the journal Science Robotics.
