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Harvard’s RoboBee Takes Flight with Improved Landing Mechanics

The Harvard RoboBee, a remarkable achievement in micro-robotics, has demonstrated impressive flight capabilities, including hovering, diving, and general aerial maneuverability. However, effective landing techniques were needed to complement its flight abilities.

Engineers at the Harvard Microrobotics Laboratory have drawn inspiration from nature to enhance the RoboBee’s landing mechanism. Newly developed landing gear, modeled after the structure and functionality of crane flies, promises to improve the robot’s ability to transition smoothly from air to ground.

In a recent publication in Science Robotics, Robert Wood, the Harry Lewis and Marlyn McGrath Professor of Engineering and Applied Sciences at the John A. Paulson School of Engineering and Applied Sciences (SEAS), led the implementation of jointed legs that facilitate gentler landings. These updates, alongside an upgraded control system, allow the RoboBee to decelerate effectively before touchdown, achieving a soft landing.

Protecting the intricate piezoelectric actuators, which serve as the robot’s energy-efficient “muscles” for flight, is crucial, as they are vulnerable to damage from hard landings. The RoboBee’s lightweight design, weighing merely a tenth of a gram and sporting a wingspan of 3 centimeters, contributes to its landing challenges. Previous models faced significant instability, generating ground effects similar to turbulence caused by helicopter blades.

Christian Chan, a graduate student and co-first author of the study, explained the previous landing approach: “In earlier attempts, we’d cut off power just above the ground and let it drop, hoping it would stabilize.” The recent advancements in the controller allow for better adaptation to these ground effects, a focus led by Nak-seung Patrick Hyun, a former postdoctoral researcher. Hyun conducted controlled landing tests on various surfaces, including leaves and rigid materials.

“Ensuring a safe landing for any flying vehicle hinges on reducing speed before impact and managing energy during the landing,” stated Hyun, who is now an assistant professor at Purdue University. He emphasized that even small wing movements of the RoboBee can lead to significant ground effect challenges, particularly when landing is involved.

The team leveraged the crane fly’s design—an insect known for its graceful landings and short flights—to conceptualize their new leg designs. With similar size and proportions, the crane fly’s long, jointed legs were deemed effective in absorbing impact and offering stability during landings. Carrying out studies based on observations from Harvard’s Museum of Comparative Zoology, the researchers created prototypes that mirror the crane fly’s leg structure.

Alyssa Hernandez, a postdoctoral researcher with a background in biology and insect locomotion, noted, “The RoboBee serves as a unique vehicle to bridge the gap between biology and robotics. By looking to the diverse world of insects for inspiration, we can continue to refine the robot while simultaneously utilizing it for biological inquiry.” This symbiotic relationship offers new avenues for research and development.

Currently, the RoboBee operates through tethered control systems, which the team aims to eventually replace with onboard electronics for enhanced autonomy in flight and control. Wood articulated the vision for these advancements: “Our long-term goal focuses on creating a fully autonomous vehicle. However, until we solve electrical and mechanical challenges associated with tethered devices, achieving safe landings remains a crucial milestone.”

The potential applications of the RoboBee extend beyond aviation. Future uses may include environmental monitoring, disaster response, and even artificial pollination, painting a picture of RoboBees facilitating the growth of urban gardens and vertical farms.

This research received funding through the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE 2140743.

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