Wheel in the Sky Keeps on Turning

Traveling by air is the fastest way to get around. There is no need to take indirect paths, and there are no forests, hills, or other obstacles standing in the way to slow you down. For this reason, aerial drones can go where no other robots can, and they can get there faster. That is, until they exhaust their energy supplies. Staying up in the air requires a lot of power, yet drones must limit the weight of the batteries they carry to stay airborne. For this reason, flight times are relatively short.

This is a major limitation that prevents drones from being deployed for a wide range of applications that they might otherwise be perfect for. Until a new innovation comes along that significantly extends the capacity of batteries, developers will have to get creative to keep drones operating longer. One popular method that is being explored currently is multimodal robots. If a drone can operate on both land and in the air, it can save energy by traveling on the ground until the going gets too tough, then take to the air only when necessary.

But as you might expect, combining both capabilities into one vehicle adds a lot of complexity and weight. That, in turn, hinders the performance of both modes of locomotion. An interesting robot design recently described by researchers at the Singapore University of Technology and Design looks like it might change this present paradigm, however. Their wheel-shaped robot can roll along the ground and take to the sky, and because of the way that it reuses parts, it is lightweight and efficient.

Called the Aerial and Terrestrial mode Operating Mono-wing (ATOM), the device is about the size of a basketball and weighs just 124 grams. ATOM’s defining characteristic is its unique structure. It takes the form of a lightweight wire frame shaped like a snare drum with a single wing inside. The internal blade resembles the seed of a maple tree — those helicopter-like samaras that spin as they fall — providing lift when ATOM rotates in flight mode.

To roll on the ground, ATOM uses its outer frame as a wheel. When it is time to fly, it tips slightly to begin spinning its body, transforming into a mono-wing drone. This dual-use of components eliminates the need for separate mechanisms for each mode, saving both weight and energy. The robot is powered by just two small actuators and a pair of rotors that provide thrust in both land and air modes. Additional components include small circuit boards and a lightweight battery that keeps everything running.

While most hybrid robots are only energy-efficient in one of their operating modes, ATOM is able to maintain efficiency on both land and in the air. In terrestrial mode, it achieves particularly low energy consumption and can navigate a variety of surfaces, even climbing slopes with up to a 15° incline before it has to take to the air.

ATOM may be only a stopgap measure, but until better energy storage technologies are developed, it could make it practical to use drones for many more applications. With minimal components and maximum versatility, ATOM could very well be the model for the next generation of adaptable drones.