MAVLab TU Delft / YouTube
MAVLab TU Delft / YouTube

Dutch engineers have created an easy flying robot, which allows you to study the mechanisms underlying the flight of insects. Despite the absence of the tail, it can control the movement around the vertical axis with the help of the movements of the wings, creating torques along the remaining axes. Experiments with the robot allowed to confirm the hypothesis that the Drosophila and some other insects use a similar mechanism during sharp turns. The article is published in  Science .

Insects know how to perform extremely fast and accurate maneuvers, helping them avoid dangers or catch prey. Scientists studying insect flight mechanisms and engineers seeking to replicate them in artificial devices have to rely on direct observations, as well as the theoretical models and experimental aircraft developed on their basis. Some developments in the field of flyers using insect-like mechanisms are already there, but almost always their movements are limited due to wires, insufficient capacitive battery or other factors.

A group of engineers from Delft University of Technology and Wageningen University, led by Guido de Croon, created a research robot capable of autonomously flying for five minutes.

It is made according to the scheme of a flywheel with two pairs of wings attached to a common base. The wingspan of the robot is 33 centimeters, and its mass is 28.2 grams. Since the apparatus is devoid of the tail, as in insects, control of the direction of motion occurs solely with the help of wings.

Each pair of wings is driven by a separate motor, connected to the wings through several gears. To control the torque on three axes, engineers used several mechanisms. The roll (motion around the longitudinal axis) is set by changing the frequency of the strokes on one of the pairs of wings, which leads to a change in thrust and the inclination of the robot to one side. Change of pitch (movement around the transverse axis) occurs by simultaneous rotation of the upper edge of pairs of wings relative to the base of the robot. Due to this, pairs of wings become disposed asymmetrically and the robot tilts in the opposite direction relative to them. To control the yaw (movement around the vertical axis), engineers added a swivel mechanism to the bottom of the robot,

The engineers decided to demonstrate the suitability of the robot to study insect movements by examining the sharp turns that the fruit flies commit during an escape from predators. In several papers, a hypothesis has been advanced that these Drosophila maneuvers are performed in two stages. During the first phase, the Drosophila is rotated by a combination of torque around the longitudinal and transverse axes, without using a vertical axis, and, in fact, does not control the direction due to the fact that the information from the visual system does not arrive quickly enough. In the second phase, she uses the received visual information in order to stabilize her movement and compensate for the “skid” that has arisen.During the experiments, the robot simulated the maneuvers of the fruit fly. Despite the 55-fold difference in size, speed and overload during the turn were comparable. The tests showed that the robot with the completely disabled function of direct control of movement around the vertical axis was able to repeat the trajectory of flight of Drosophila described in other studies. Thus, the researchers showed that Drosophila can use pitch and roll changes to create torque that rotates around the vertical axis.

Also, the researchers conducted experiments with the included system of turning the lower edges of the wings to control the yaw, so that they managed to remove the “skid” that appears at the end of the maneuver both in the robot and in the fruit fly. Nevertheless, the speed of the whole maneuver did not increase from this, which, according to the researchers, also indirectly indicates that the Drosophila do not actively control movement around the vertical axis during the turn.Over the years, engineers from Harvard University have been working on creating winged robots similar to live organisms. They created a robocop, capable of sticking to leaves and diving under water and using a wire to feed. And recently they demonstrated the flight of a fully autonomous robot with a mass of 190 milligrams, receiving energy from the laser beam.