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RoboBee Can Now Pivot on a Dime

Since becoming the first insect-inspired robot to take flight, Harvard University’s famous little robotic bee, dubbed RoboBee, has achieved novel perching, swimming, and sensing capabilities, among others.

More recently RoboBee has hit another milestone: precision control over its heading and lateral movement, making it much more adept at maneuvering. As a result, RoboBee can hover and pivot better in midair, more similarly to its biological inspiration, the bumblebee. The advancement is described in a study published this past December in IEEE Robotics and Automation Letters.

“One particularly exciting area is assisted agriculture, as we look forward to applying these vehicles in tasks such as pollination, attempting to replicate the feats of biological insects and birds,” says Rebecca McGill, a Harvard Ph.D. candidate in materials science and mechanical engineering who helped codesign the new RoboBee flight model.

The increased level of flight control will be useful in a variety of situations where precision flight is required. Consider the requirement to explore sensitive or risky areas—a task for which RoboBee would be ideally suited—or the necessity for a big group of flying robots to move in swarms.

In a variety of situations where precision flight is required, the increased level of control over flight will be advantageous. Consider the requirement to investigate sensitive or risky areas—a task that RoboBee could excel at—or the necessity for a huge group of flying robots to move in swarms.

“One particularly exciting area is assisted agriculture, as we look forward to applying these vehicles in tasks like pollination, attempting to achieve the feats of biological insects and birds,” says Rebecca McGill, a Harvard Ph.D. candidate in materials science and mechanical engineering who helped codesign the new RoboBee flight model.

But, for good reason, achieving precision control with a flapping-winged robot has proven difficult. Helicopters, drones, and other fixed-wing vehicles can adjust their direction and lateral movement by tilting their wings and blades and including rudders and tail rotors. In order to help the robot rotate while standing in midair, flapping robots must move their wings up and down at varied speeds. A force known as yaw torque is produced by this type of rotary movement.

However, to generate the needed yaw torque to spin the body, flapping-wing micro-aerial vehicles (FWMAVs) like RoboBee must carefully balance the upstroke and downstroke rates inside a single fast-flapping cycle. “In FWMAVs, this makes yaw torque difficult to create,” McGill explains.

McGill and her team devised a new model to analyse how different flapping signals associated with flight affect forces and torques, allowing them to determine the ideal yaw torque (along with thrust, roll torque, and pitch torque) combination in real time.

“The model improves our understanding of how much yaw torque is produced by different flapping signals, giving better, controllable yaw performance in flight,” explains McGill.

In the team’s study, they tested the new model through 40 different flight scenarios with RoboBee, while varying the control inputs and observing the thrust and torque response for each flight. With its new model, the RoboBee was able to fly in a circle while keeping its gaze focused on the center point, mimicking a scenario in which the vehicle focuses a camera on a target while circling around it.

“Our experimental results revealed that yaw torque filtering can be mitigated sufficiently…to achieve full control authority in flight,” says Nak-seung Patrick Hyun, a postdoctoral fellow at Harvard who was also involved in the study. “This opens the door to new maneuvers and greater stability, while also allowing utility for onboard sensors.”

Advances like this, according to McGill and Hyun, will not only assist robots in the field with jobs like pollination and emergency response but will also give humans greater insights into biology. “flapping-wing robots are exciting because they allow us to explore and learn about insect and bird flight mechanisms through imitation, creating a ‘two-way’ path of discovery towards both robotics and biology,” says Hyun, who adds that the team is particularly interested in studying aggressive aerial maneuvers with their new RoboBee flight model.

What do you think?

Written by Emma Ava

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