Researchers have taken inspiration from a mosquito's ability to fly and land in the dark to develop a new collision-avoidance sensory system that has been tested on a quadcopter. The international team of scientists, led by Professor Richard Bomphrey at the Royal Veterinary College (RVC) in London, looked at the sensory mechanism in the male Culex quinquefasciatus mosquito and found a way to mimic the insect's ability to use airflow to detect obstacles.
As most campers can latest, one of the maddening things about sleeping outdoors is how it's often impossible to know if a mosquito has landed on you until after it has made off with its meal. There are a number of reasons for this, but an important one is that mosquitoes can land very lightly even in pitch darkness.
They manage this thanks to mechanosensing, which is a responsivity to mechanical stimuli that allows them to sense obstacles without using their eyes. Unlike bats, which navigate by means of a biological sonar system, mosquitoes use a combination of their wings, antennae, and airflow.
According to the team, mosquitoes fly by beating their elongated wings very rapidly, producing fast jets of air that provide lift. If these jets encounter an obstacle, these airflow patterns change shape, which can be detected by an array of receptors at the base of the mosquito's antennae called the Johnston’s organ. This allows the insect to build a picture of its surroundings using "aerodynamic imaging," allowing it to map where the ground and other obstacles are located.
To learn how the mosquito does this, the team made high-speed recordings of its flight and then analyzed it using computational fluid dynamics simulations. They found that the Johnston's organs were ideally located for measuring the pattern changes because the pressure differences were the greatest above the mosquito's head, and that they worked best at low altitude.
The mosquito is exploiting the ground effect, which is the increased lift and aerodynamic drag generally experienced by aircraft when flying under two wing-lengths from the ground. When the simulation took this into account, the researchers found that the Culex mosquito could detect surfaces more than 20 wing lengths away – much farther than previously thought.
The team then used these findings to provide a miniature quadcopter with aerodynamic imaging by fitting it with a bio-inspired sensor device. This device consisted of an array of probe tubes connected to differential pressure sensors placed for maximum sensitivity. After a series of test flights, the quadcopter was then allowed to fly autonomously.
The team found that the quadcopter could detect surfaces at a sufficient distance to avoid the ground or walls with little or no data processing, In addition, the new system is said to be lightweight, power-efficient, and scalable.
"It's important to understand how such a significant group of insects navigate around the world," says Bomphrey. "If we are to live in a future where ever more work is done by flying vehicles and drones, it could be useful to take some inspiration from mosquitoes to make our machines safer when operating close to buildings or other infrastructure.
"There is no reason to stop at small fliers, this surface detection capability could be scaled-up to helicopters, making them a little safer when flying in treacherous, low-visibility conditions."
The research was published in Science and the ground detection capabilities of the quadcopter are demonstrate din the video below.
Source: University of Leeds
