Washington State University (WSU) researchers have developed a robotic bee that can fly fully in all directions like a real bee, marking a significant development in robotics.
The Bee++ prototype is the first to fly stably in all directions, including the tricky twisting motion known as yaw. The robot consists of four wings made out of carbon fiber and mylar, as well as four lightweight actuators that can control the wing independently. This design enables the Bee++ to achieve the six degrees of free movement that a typical flying insect displays.
The research was led by Néstor O. Pérez-Arancibia, Flaherty associate professor in WSU’s School of Mechanical and Materials Engineering, who has been working on developing artificial flying insects for more than 30 years. The artificial flying insects could someday be used for many applications, including artificial pollination, search and rescue efforts in tight spaces, biological research, or environmental monitoring, including in hostile environments. But just getting the tiny robots to take off and land required the development of controllers that act the way an insect brain does.
Their initial work was focused on developing a two-winged robotic bee, but it was limited in its movement. In 2019, Pérez-Arancibia and his team achieved a breakthrough by building a four-winged robot light enough to take off.
To do two maneuvers known as pitching or rolling, the researchers make the front wings flap in a different way than the back wings for pitching and the right wings flap in a different way than the left wings for rolling, creating torque that rotates the robot about its two main horizontal axes.
But being able to control the complex yaw motion is tremendously important. Without it, robots spin out of control, unable to focus on a point, and then they crash. 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,” Pérez-Arancibia said. “For many years, people had theoretical ideas about how to control yaw, but nobody could achieve it due to actuation limitations.”
To allow their robot to twist in a controlled manner, the researchers took a cue from insects and moved the wings to flap in an angled plane. They also increased the frequency of wing flapping from 100 to 160 times per second, generating the necessary lift and agility for stable flight.
The Bee++ weighs 95 milligrams with a 33-millimeter wingspan, which is much more than the naturally occurring bees that weigh around 10 milligrams. The robotic bee can only fly autonomously for about five minutes at a time, so it is mostly tethered to a power source through a cable.
The research team is also working to develop other types of insect robots, including crawlers and water striders.
- Ryan M. Bena, Xiufeng Yang, Ariel A. Calderón, Néstor O. Pérez-Arancibia. High-Performance Six-DOF Flight Control of the Bee++: An Inclined-Stroke-Plane Approach. IEEE Transactions on Robotics, 2023; DOI: 10.1109/TRO.2022.3218260