Tiny planes and subs could be the next hurricane hunters
Kamran Mohseni envisages a day when the unmanned vehicles in his laboratory at the University of Florida will swarm over, under and through hurricanes to help predict the strength and path of the storms.
The tiny, autonomous craft – some fly, others dart under the waves – can spy on hurricanes at close range without getting blown willy-nilly, while sensors on board collect and send in real time the data scientists need to predict the intensity and trajectory of storms: pressure, temperature, humidity, location and time.
Mohseni said people always ask him how the miniature flying machines – just 15 centimetres long and about the weight of an iPod Nano – can take on one of the monster storms.
“Our vehicles don’t fight the hurricane; we use the hurricane to take us places,” said Mohseni, professor in the department of mechanical and aerospace engineering and the department of electrical and computer engineering.
The aerial and underwater vehicles can be launched with commands from a laptop hundreds of kilometres from the eye of a hurricane. Mohseni and a team of graduate students use mathematical models to predict regions in the atmosphere and ocean that can give the vehicles a free ride towards their destination. Once in the vicinity, they can be powered off to wait for a particular current of wind or water.
When they detect the current they need for navigation, they power back on, slip into the current, then power off again to conserve fuel as the current carries them to a target location. In essence, they can go for a fact-gathering ride on hurricane winds and waters.
The devices are a departure from current technology, which uses hurricane reconnaissance aircraft to punch through a storm’s eye wall and release dropsondes, sensors that free-fall and might or might not collect helpful data. Underwater data are even more difficult to collect today, although just as important, considering that the warm, moist air on the ocean surface provides fuel for hurricanes.
Mohseni’s vehicles, even launched hundreds at a time, also reduce the cost of hurricane reconnaissance. “We are going the opposite direction,” said Mohseni, director of his university’s new Institute for Networked Autonomous Systems. “We don’t have anything that is super duper. We have cheap sensors, but with a lot of them you can significantly increase the accuracy of your measurements.”
The prototypes produced at the institute are about R2 500 apiece and are too small and lightweight to cause damage when they hit something, a big consideration in hurricane-force winds and waves. Mohseni does not use a landing strip to test the aerial vehicles; he just tells them to crash, picks them up and flies them again. The carbon fibre shell of the aerial vehicles is wafer-thin but resilient.
The vehicles also are smart. Mohseni developed a co-operative control algorithm that allows them to form a network and learn from the data they take in, for example, by adjusting their course when needed. This feature makes them useful for applications beyond hurricanes, for example measuring in extreme environments such as the polar ice caps.
Although advances in microfabrication, communications, computer processing and computation have helped boost development of the vehicles, Mohseni has drawn inspiration from biomimicry. He had been studying fluid dynamics, working on propulsion, when a biologist mentioned that jellyfish navigate in much the same way as the mechanical system Mohseni wanted to develop. After studying jellyfish, cuttle-fish and squid, Mohseni developed a mathematical model of their thrust and used that model to develop the motors for his underwater sensor vehicles. He now has small submarines capable of autonomous docking using technology mimicking jellyfish and squid, and the sea creatures are common fixtures in his laboratory.
Source: University of Florida