Scientists are building a robotic bee that can fly in all directions

Photo credit: WSU.

With four carbon fiber and Mylar wings, and four lightweight actuators to control each wing, the Bee++ prototype is the first to stably fly in all directions.

Washington State University researchers have developed a robotic bee that can fly completely in all directions.

With four carbon fiber and Mylar wings, and four lightweight actuators to control each wing, the Bee++ prototype is the first to stably fly in all directions.

This includes that tricky twisting motion known as yaw, with the Bee++ fully achieving the six degrees of free motion exhibited by a typical flying insect.

Led by Néstor O. Pérez-Arancibia, Flaherty Associate Professor at WSU’s School of Mechanical and Materials Engineering, the researchers report on their work in the diary, IEEE Transactions on Robotics. Pérez-Arancibia will present the results later this month at the IEEE International Conference on Robotics and Automation.

Researchers have been trying to develop artificial flying insects for more than 30 years, Pérez-Arancibia said. They could one day be used for many applications, including artificial pollination, confined space search and rescue, biological research or environmental monitoring, even in hostile environments.

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

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

Researchers first developed a two-winged robotic bee, but it was restricted in its movement. In 2019, Pérez-Arancibia and two of his graduate students first built a four-winged robot that was light enough to take off. To perform two maneuvers known as pitching or rolling, the researchers make the front wings flap differently than the rear wings when pitching, and make the right wings flap differently than the left wings when rolling, creating a torque that turns the robot from its two horizontal ones main axes.

But being able to control the complex yaw motion is hugely important, he said. Without them, robots get out of control and can’t focus on one point. Then they crash.

“If you can’t control yaw, you’re extremely limited,” he said. “If you’re a bee, here’s the flower, but if you can’t control yaw, you’re constantly spinning while trying to get there.”

The availability of all movement degrees is also of crucial importance for evasive maneuvers or the pursuit of objects.

“The system is extremely unstable and the problem is very serious,” he said. “For many years there have been theoretical ideas about how to control yaw, but due to operational limitations nobody has been able to implement them.”

In order for their robot to rotate in a controlled manner, the researchers took inspiration from insects and moved the wings so that they flap in an angled plane. They also increased the frequency at which their robot can flap its wings per second – from 100 to 160 times per second.

“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.

With a weight of 95 mg and a wingspan of 33 millimeters, the Bee++ is still larger than real bees, which weigh around 10 milligrams.

Unlike real insects, it can only fly autonomously for about five minutes at a time and is therefore mostly tied to a power source via a cable. Researchers are also working on developing other types of insect robots, including caterpillars and water striders.

Pérez-Arancibia’s former graduate students at the University of Southern California, Ryan M. Bena, Xiufeng Yang, and Ariel A. Calderón, co-authored the article.

The work was funded by the National Science Foundation and DARPA. The WSU Foundation and the Palouse Club have also provided support through WSU’s Cougar Cage program.

Written by Tina Hilding.


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