Researchers build bee robot that can twist

PULLMAN, Wash. – Researchers from Washington State University have successfully developed a robotic bee capable of full flight in all directions. This innovative creation marks a significant achievement in the field of robotics.

The Bee++ prototype, designed by Washington State University researchers, incorporates four wings constructed from carbon fiber and mylar, along with four lightweight actuators that independently control each wing. This design enables the robotic bee to achieve stable flight in all directions, including the challenging yaw motion. Notably, the Bee++ successfully emulates the six degrees of free movement observed in natural flying insects, showcasing its ability to maneuver with agility. This achievement marks a significant advancement in robotic flight capabilities.

The groundbreaking work on the development of the robotic bee, named Bee++, was led by Néstor O. Pérez-Arancibia, who holds the position of Flaherty associate professor in WSU’s School of Mechanical and Materials Engineering. The researchers have documented their findings in the journal IEEE Transactions on Robotics. Additionally, Pérez-Arancibia is scheduled to present the results at the upcoming IEEE International Conference on Robotics and Automation at the end of this month. This presentation will provide an opportunity to share their groundbreaking achievements with the wider robotics community.

According to Pérez-Arancibia, the development of artificial flying insects has been a research pursuit spanning over three decades. These robotic insects hold potential for various applications in the future. For instance, they could be employed in artificial pollination, facilitating the pollination process in situations where natural pollinators are scarce. Additionally, they could assist in search and rescue operations in confined spaces, where human access is challenging. Furthermore, their use in biological research and environmental monitoring, even in hostile environments, presents promising opportunities. The multifaceted applications of artificial flying insects highlight their potential to contribute to diverse fields.

But just getting the tiny robots to take off and land required development of controllers that act the way an insect brain does.

“It’s a mixture of robotic design and control,” he said. “Control is highly mathematical, and you design a sort of artificial brain. Some people call it the hidden technology, but without those simple brains, nothing would work.”

Initially, the researchers focused on developing a two-winged robotic bee, but it had limited mobility. In 2019, Pérez-Arancibia and two of his PhD students achieved a significant breakthrough by constructing a four-winged robot that was light enough to achieve liftoff. To execute specific maneuvers such as pitching or rolling, the researchers devised a distinct flapping pattern for the front wings compared to the back wings for pitching, and for the right wings compared to the left wings for rolling. This differential flapping creates torque, enabling the robot to rotate about its two primary horizontal axes. This innovative approach enhances the robot’s agility and control during flight.

Pérez-Arancibia emphasizes the significance of effectively controlling the complex yaw motion in robotic flight. This capability is crucial as it allows the robot to maintain stability and focus on specific points or targets during its flight. Without proper control of yaw, robots can spiral out of control and lose their ability to navigate accurately. This lack of control often leads to crashes and hampers the robot’s functionality. Therefore, the successful implementation of yaw control in the robotic bee’s design is a significant achievement, enabling precise maneuvering and enhancing the robot’s overall flight capabilities.

“If you can’t control yaw, you’re super limited,” he said. “If you’re a bee, here is the flower, but if you can’t control the yaw, you are spinning all the time as you try to get there.”

Having all degrees of movement is also critically important for evasive maneuvers or tracking objects.

“The system is highly unstable, and the problem is super hard,” he said. “For many years, people had theoretical ideas about how to control yaw, but nobody could achieve it due to actuation limitations.”

To achieve controlled twisting movement in their robot, the researchers drew inspiration from insects. They implemented a design where the wings flap in an angled plane, mimicking the natural motion of insect wings. This design adaptation allows the robot to twist in a controlled manner, enhancing its maneuverability. Additionally, the researchers increased the frequency of wing flapping from 100 to 160 times per second. This higher flapping rate enables the robot to generate the necessary lift and agility required for stable flight and precise movements. By incorporating these design modifications, the researchers have made significant strides in emulating the flight capabilities of insects in their robotic bee.

“Part of the solution was the physical design of the robot, and we also invented a new design for the controller – the brain that tells the robot what to do,” he said.

The Bee++ has a weight of 95 mg and a wingspan of 33 millimeters, making it larger than real bees that typically weigh around 10 milligrams. While real insects can fly autonomously for extended periods, the Bee++ has a limited autonomous flight time of approximately five minutes. As a result, it is often connected to a power source through a tether cable. The researchers are not solely focused on robotic bees but are also engaged in developing other types of insect-inspired robots, such as crawlers and water striders. This diversification of their research aims to explore and harness the unique locomotion and capabilities found in different types of insects.

The article co-authored by Pérez-Arancibia features his former PhD students, Ryan M. Bena, Xiufeng Yang, and Ariel A. Calderón, from the University of Southern California. The research project received funding from the National Science Foundation (NSF) and the Defense Advanced Research Projects Agency (DARPA). Additionally, support for the project was provided by the WSU Foundation and the Palouse Club through WSU’s Cougar Cage program. These funding sources have played a crucial role in supporting and advancing the research efforts behind the development of the robotic bee and its associated technologies.

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