Agile Robot Inspired By Fruit Flies
Written by Harry Fairhead   
Saturday, 15 September 2018

Developed in order to study the aerodynamics of fruit-fly maneuvers, the DelFly Nimble is a novel flapping wing robot with exceptional flight characteristics. It is the latest in a series of micro air vehicles from MAVLab at the Delft University of Technology.

The DelFly Project dates from 2005 when a group of 11 students designed the original to participate in an international MAV competition in Germany. Having won the Symposium for Bachelor thesis projects of the faculty of Aerospace Engineering of TUDelft, the team built the first DelFly I with a wingspan of 50 cm and a weight of 21 grams. The competition jury was very impressed by its unique design which let it fly both fast and slow (near hover) while also carrying a camera onboard.


The follow-up design, the DelFly II in 2007was smaller and lighter and capable of hovering, and the following year an even small model, the DelFly Micro, weighing only 3.07 grams with a wingspan of 10 cm was achieved, capable of flights of up to 3 minutes by controlling thrust roll and pitch. Because it had also a camera onboard, it was declared by Guinness Book of Records 2009 as the “Smallest camera-equipped aircraft in the world”.


The DelFly Explorer, designed in 2013, was the first flapping wing MAV that could perform autonomous flight. It carries a stereo vision system with processing onboard which is used to avoid obstacles. It is also equipped with a barometer to maintain its height. This combination of sensors enables the 20 grams DelFly Explorer to perform a take-off, to ascend to a chosen height and to fly around for up to 9 minutes without the need of external control. 

The 2018 DelFly Nimble is the first  tailless design and, unlike the previous designs, is controlled by its independently actuated wings, which makes it very agile and allows flight in any direction. It features on the cover of the latest issue of the print magazine Science, for a study in collaboration with Experimental Zoology Group of Wageningen UR, in which researchers discovered and described a new aerodynamic phenomenon helping fruit flies to evade dangers:

We have programmed the robot such that it mimics the hypothesized control actions of fruit flies during these rapid banked turns: simultaneous rotations around its forward-pointing (roll) and transversal (pitch) axes. The robot was able to replicate these maneuvers with a remarkable level of similarity, including the rotation around its third, vertical (yaw) axis.


We have previously reported on biologically inspired robots whose designs implement something that looks like an animal and moves like that animal, see for example Festo's Flying Fox And Spider Robots Are Worth Seeing. In this case robotics has been employed to study a phenomenon that it hard to observe.

The abstract of the paper by Karásek et al. explains that insect flight is hard to study by virtue of it being so fast and agile:

Insects are among the most agile natural flyers. Hypotheses on their flight control cannot always be validated by experiments with animals or tethered robots. To this end, we developed a programmable and agile autonomous free-flying robot controlled through bio-inspired motion changes of its flapping wings. Despite being 55 times the size of a fruit fly, the robot can accurately mimic the rapid escape maneuvers of flies, including a correcting yaw rotation toward the escape heading. Because the robot’s yaw control was turned off, we showed that these yaw rotations result from passive, translation-induced aerodynamic coupling between the yaw torque and the roll and pitch torques produced throughout the maneuver. The robot enables new methods for studying animal flight, and its flight characteristics allow for real-world flight missions. 

The DelFly Nimble is both lightweight, making it inherently safe, and highly agile. It is a programmable and natural-looking robot and is will no doubt find uses that call for these characteristics.


More Information

The DelFly Project

A tailless aerial robotic flapper reveals that flies use torque coupling in rapid banked turns by Matěj Karásek et al. Science, Vol 361, Iss 6407,2018
DOI: 10.1126/science.aat0350

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Last Updated ( Saturday, 15 September 2018 )