Researchers regularly take a look at nature how they solve certain problems. Bionicists - an artificial word from biology and technology - have already recreated location systems such as that of dolphins or copied the caustic bars and developed the Velcro fastener from them. Leonardo da Vinci was already inspired for his aircraft from birds. But why shouldn't that work the other way around? Can technical solutions give deeper insight into unresolved biological phenomena?
A team from the Technical University of Delft, the French Centre national de la recherche scientifique (CNRS) and the University of Aix-Marseille has now shown that drones can estimate the direction of gravity by using their sensors to visually detect the movements around them and combine them with modeling their own movement, i.e. predicting how they will move. These results, which the researchers have published in the journal "Nature", are an important step on the way to the development of tiny autonomous drones. In addition, it may be possible to explain how flying insects can be distinguished from each other above and below. This shows how the synergy between robotics and biology can lead to technological advances and new biological research approaches.
While drones usually use accelerometers to estimate the direction of gravity, the way flight insects do was so far a mystery because they have no specific sense of acceleration. The scientists therefore examined the optical flow, that is, the way an individual perceives movements in relation to its environment. It is the visual impression that runs over our retina when we move. For example, if we sit in one train, the trees pass faster next to the tracks than the mountains further away. However, the optical river alone is not enough for an insect to recognize the direction of gravity. The research team then discovered that the combination of the optical river with a prediction of the movement makes it very possible to develop a feeling for gravity.
The researchers' experiments with flying robots show that this principle leads to a stable but slightly oscillating bearing control. According to the scientists, the vibrations are actually strongly reminiscent of the flight of insects. However, checking the assumption could be difficult because it affects brain processes that are difficult to monitor during the flight of an animal. "This hypothesis can theoretically explain how flying insects determine gravity, but we still need confirmation from the biological experiment that they actually use this mechanism," said the researchers, according to a message from the institutions involved.
