An innovative insect-inspired flying robot, created by TU Delft scientists from the Micro Air Vehicle Laboratory (MAVLab), was recently showcased in the September 14 th issue of Science.
Experiments with the world's first autonomous, free-flying and agile flapping-wing robot have provided insights into how fruit flies control aggressive escape maneuvers. In addition, the robot’s extraordinary flight qualities will pave the way for new drone applications.
DelFly, in forward flight. (credit: MAVLab TU Delft)
Flying animals both power and regulate flight by flapping their wings. This allows small natural flyers such as insects to hover near a flower, but also to quickly escape danger, which everyone would have observed when trying to swat a fly.
Animal flight has always interested biologists, who not only research their complex wing motion patterns and aerodynamics, but also their sensory and neuro-motor systems during such swift maneuvers. Recently, flying animals have also become a source of stimulation for robotics scientists, who try to build lightweight flying robots that are agile, power-efficient, and even scalable to insect sizes.
Novel highly agile flying robot
TU Delft scientists from the MAVLab have created a novel insect-inspired flying robot; so far unrivaled in its performance, and but still having a simple and easy-to-create design. As in flying insects, the robot’s flapping wings, beating 17 times per second, not only produce the lift force required to stay airborne but also control the flight via minor modifications in the wing motion. Inspired by fruit flies, the robot’s control mechanisms have been shown to be very effective, enabling it not only to hover on the spot and fly in any direction but also be extremely agile.
“The robot has a top speed of 25 km/h and can even perform aggressive manoeuvres, such as 360-degree flips, resembling loops and barrel rolls”, says Matěj Karásek, the first author of the study and the robot’s main designer. “Moreover, the 33 cm wingspan and 29 gram robot has, for its size, excellent power efficiency, allowing 5 minutes of hovering flight or more than a 1 km flight range on a fully charged battery.”
Research on fruit fly escape maneuvers
Besides being a novel, autonomous micro-drone, the robot’s flight performances, integrated with its programmability also make it well-suited for study into insect flight. To this end, TU Delft has partnered with Wageningen University.
“When I first saw the robot flying, I was amazed at how closely its flight resembled that of insects, especially when manoeuvring. I immediately thought we could actually employ it to research insect flight control and dynamics”, says Prof. Florian Muijres from the Experimental Zoology group of Wageningen University & Research. As a result of Prof. Muijres’ earlier work on fruit flies, the team planned to program the robot to imitate the hypothesized control actions of these insects during high-agility escape maneuvers, such as those used when one tries to swat them.
The robot’s maneuvers closely resembled those seen in fruit flies. The robot was even able to exhibit how fruit flies control the turn angle to maximize their escape performance.
“In contrast to animal experiments, we were in full control of what was happening in the robot’s “brain”. This allowed us to identify and describe a new passive aerodynamic mechanism that assists the flies, but possibly also other flying animals, in steering their direction throughout these rapid banked turns”, adds Karásek.
Potential for future applications
Insect-inspired drones have a high potential for novel applications, as they are light-weight, safe around humans and are able to fly more efficiently than more traditional drone designs, especially at smaller scales.
However, until now, these flying robots had not realized this potential since they were either not agile enough—such as our DelFly II—or they required an overly complex manufacturing process.”
Prof. Guido de Croon, MAVLab Scientific Leader
The robot in this research, named the DelFly Nimble, builds on proven manufacturing approaches, uses off-the-shelf parts, and its flight endurance is sufficiently long to be of interest for real-world applications.
The DelFly Nimble will be further advanced within the TTW project, ‘As nimble as a bee’, which is a partnership between TU Delft and Wageningen University, sponsored by the Dutch science foundation NWO.