Robot bees have learned how to not only fly but also land. After more than 10 years of development, the robot bees successfully landed safely with their long legs following their flap of wings, indicating that the day for practical application may not be far off.
Robert Wood, a professor at Harvard University, said on the 17th, "The ultra-small flying robot RoboBee has developed technology that helps it land smoothly and gracefully from the air to the ground." The research findings were published that day in the international journal Science Robotics.
RoboBee is an ultra-small flying robot being developed by Harvard University since 2013. As its name suggests, it is the size of a bee, capable of flying like a bee and hovering in the air. The wings measure 3 cm and weigh only 0.08 g. It reduced its weight by using a lightweight piezoelectric element instead of a motor.
A piezoelectric element changes shape when current flows through it. The research team was able to make RoboBee flap its wings 120 times per second by turning the current on and off. This is comparable to the level of actual insects.
While RoboBee demonstrated flying capabilities comparable to those of bees, the real challenge was landing. Its very light weight and short wing length made it unable to withstand the air vortex generated during landing. It is easy to understand when considering the strong wind that arises when a helicopter approaches the ground.
Christian Chan, a graduate student at Harvard involved in the research, said, "Until now, when RoboBee attempted to land, we were at a level of just shutting off the robot above the ground and hoping for a proper landing."
To ensure RoboBee's safe landing, it was crucial to disperse energy just before landing. Hyun Nak-sung, a professor at Purdue University who participated in the development of RoboBee, explained that "the success of landing for any flying object relies on minimizing speed just before impact and quickly dispersing energy after impact," adding that "even small flapping like that of RoboBee can't ignore the ground effect, and post-landing can result in bouncing or rolling, complicating the issue further."
The Harvard research team drew inspiration from nature to give RoboBee a safe landing. They mimicked the graceful landing of the crane fly. Crane flies appear from spring to autumn and are often mistaken for giant mosquitoes, but they are harmless insects. Crane flies have long jointed legs that can absorb shock upon landing. Their size was similar to that of RoboBee.
The research team observed crane fly specimens at the Harvard Museum of Comparative Zoology, created prototypes with various leg structures, and optimized the design by determining the best position for leg joints and segments. They also improved the performance of control devices that reduce speed when approaching the ground. With the legs of a crane fly, RoboBee landed on the ground more stably than before.
Alyssa Hernandez, a research team member, said, "RoboBee is a great platform for exploring the boundaries between biology and robotics," noting, "We can continue to improve the robot by drawing inspiration from the incredible diversity of insects."
The Harvard research team plans to use RoboBee to help maintain ecological balance in place of endangered bees. Currently, a declining bee population due to the effects of global warming is occurring worldwide. According to the Food and Agriculture Organization (FAO), 71 out of the 100 major crops rely on bees for pollination. This implies that the disappearance of bees could lead to food crises.
The Harvard research team believes that RoboBee can assist in the pollination of plants in place of bees. The leading researcher, Professor Robert Wood, stated, "The long-term goal is complete autonomous flight, but until then, we are experimenting with wired methods to address issues with electrical and mechanical components," adding, "Imagine RoboBee swarms buzzing around in future vertical farms or gardens."
References
Science Robotics (2025), DOI : https://doi.org/10.1126/scirobotics.adq3059