A new experimental drone can fly in the air as needed, then morph into a motorized wheel and roll on the ground to save energy. It could one day find use in applications such as searching disaster sites for victims trapped in the rubble.
Designed by robotics Master's student Kazuki Sugihara and colleagues at The University of Tokyo, the drone is known as the Delta – that's (sort of) an acronym for "Deformable Multilinked Multirotor with Rolling Locomotion Ability in Terrestrial Domain."
The device's ring-shaped body is made of three curved, linked segments.
Each one of these is equipped with its own motor/propeller module, which is mounted on a rod that spans the width of the segment. The module is able to swivel around the rod (sort of like a clothespin swiveling around a clothesline), allowing it to point toward the "hub" of the ring, the rim of the ring, or out to either side.
When the drone is flying, its body is oriented parallel to the ground, with all three of the thrust-vectoring propellers facing upward.
If necessary, it can uncouple one or more of the links between its segments, letting it open out of its ring shape while in flight. As is the case with other multilinked drones we've seen, this shape-changing capability could allow the Delta to fly through gaps by making itself narrow, among other possibilities.
And while flying is certainly the fastest way of traversing otherwise impassable terrain, keeping the entire weight of the drone airborne does consume a lot of battery power. That's why it can also roll like a wheel.
To do so, the Delta lands flat on one side, then swivels its propellers so that their combined thrust pushes the drone up to sit perpendicular to the ground. The prop angles are then continuously tweaked by an onboard microprocessor, allowing them to roll the drone forward, keep it from falling over, and turn it left or right.
The scientists now plan on adapting the Delta to roll over rougher surfaces, and to be capable of assessing terrain via cameras and other onboard sensors. A paper on their research can be accessed via arXiv.
And while we have previously seen other drones that can alternate between aerial and ground travel modes, Sugihara and colleagues state that most of those vehicles require separate actuators for the propellers and the wheels or legs, which add weight and complexity.
Source: The University of Tokyo
