Engineering news
It takes a huge amount of energy to lift even the smallest drones into the air, which means that until battery technology improves, they’re limited to short flight times of 20 or 30 minutes at a time. Because they use rotor blades, they also need a lot of room to manoeuvre, which limits what they can do.
However, a team at MIT are looking to change that by developing unmanned aerial vehicles that can both fly and drive around on land. This would open up possibilities for drones that can fly into inaccessible areas and then move around on the ground when they get there to pick up objects or people.
A team of researchers from the university’s Computer Science and Artificial Intelligence Laboratory have presented a new paper detailing a system of eight miniature drones that can fly and drive through a city-like setting.
“The ability to both fly and drive is useful in environments with a lot of barriers, since you can fly over ground obstacles and drive under overhead obstacles,” said lead author Brandon Araki. “Normal drones can't maneuver on the ground at all. A drone with wheels is much more mobile while having only a slight reduction in flying time.”
There was a 14 % reduction in the distance the drones could fly when wheels were added, but this was more than offset by the added distance from being able to travel on land, as driving is much more energy efficient than flying.
The researchers design a path-planning algorithm for the drones to navigate a model city build of cardboard and fabric. The environment featured ‘no-fly zones,’ parking spots and landing pads, and the drones were able to switch between road and air to make their way around.
“This work provides an algorithmic solution for large-scale, mixed-mode transportation and shows its applicability to real-world problems,” said Jingjin Yu, a computer science professor at Rutgers University who was not involved in the research.
According to Daniela Rus, director of the CSAIL lab which conducted the research, adding wheels to drones could be a better way of developing flying cars, rather than adding wings to existing road vehicles. "As we begin to develop planning and control algorithms for flying cars, we are encouraged by the possibility of creating robots with these capabilities at small scale," she said.
"While there are obviously still big challenges to scaling up to vehicles that could actually transport humans, we are inspired by the potential of a future in which flying cars could offer us fast, traffic-free transportation,” she continued.
At last week’s Paris Air Show, there were a number of potential flying car models on display, including Aeromobil’s 4.0, which uses an internal combustion engine like a road car. The biggest challenge is resolving differences between the automotive and aerospace industries, vehicle development engineer Imran Muhammad told Professional Engineering at the show. “We have to combine them and that is the biggest challenge. We have to do crash testing as automotive and then other testing as aerospace.”
Airbus were showing of a concept for an electric helicopter with four-rotors, inspired by drones. But, one of the biggest challenges with scaling up these drones is battery technology. Steve Wright, a lecturer in avionics at the University of the West of England, told PE the problem of storing energy is “absolutely the weakest link” when it comes to building drones.
“We've got enough power, what we haven't got is enough ability to store it,” he said. “If instead of 15 minutes they could do two hours, suddenly it's one of those things where you cross a threshold, and suddenly you're able to do things with them in the real world.”
Without wheels, the MIT team's tiny drones could fly for approximately 104 metres. With them, they managed 90 metres of flight, plus 252 metres of driving. Drones that take to the roads to maximise efficiency could prove a counter-intuitive solution to the energy problem.