Imagine a robot that can transform between "flying drone" and "wheeled rover" configurations. It could potentially be quite useful, but only if it works in real-world conditions. The ATMO bot was designed to do just that, by performing its transformation in mid-air.
Its name an acronym for Aerially Transforming Morphobot, ATMO was created by a team of engineers at the California Institute of Technology (Caltech). The device builds upon the technology utilized in a previous Caltech robot, the M4 (Multi-Modal Mobility Morphobot).
That particular robot flew like a regular quadcopter drone when airborne, with its four shrouded propellers spread out horizontally. Once it landed, those props folded inward, until they sat at a downwards right angle relative to the rest of the robot's body. They then served as motorized wheels, with the shrouds forming the rubber-treaded rims.
While it's a clever design, it and others like it have one flaw. If there are rocks, tufts of grass or other protruding obstacles in the landing area, they may prevent the propellers from folding all the way in. The solution to that problem is to have the robot land with its props/wheels already almost completely down.
That's where ATMO comes in.
Although each of its propellers still has its own motor for flight, just a single central motor is used to move a single joint that folds those props in (or out). The setup isn't as simple as it sounds, however.
As the propeller angle changes, and as the air pushed down by the props starts deflecting off the approaching ground, the flight characteristics of ATMO change accordingly. For this reason, the scientists had to develop a special algorithm that compensates for those changing variables by continuously adjusting the thrust delivered by each propeller.
As a result, the drone is able to perform stable "dynamic wheel landings" with its wheels/props already down. It can then zip off across the ground, with one belt drive on each side spinning up the wheels. Steering is managed via a differential that independently varies the speed of those drives.
"Here we introduce a dynamic system that hasn't been studied before," says Ioannis Mandralis, lead author of a paper on the study. "As soon as the robot starts morphing, you get different dynamic couplings – different forces interacting with one another. And the control system has to be able to respond quickly to all of that."
The paper was recently published in the journal Communications Engineering. You can see ATMO in mighty morphin' action, in the video below.
Source: Caltech
