The University of Tokyo has found a new approach to an old problem. The university's Department of Mechano-Informatics puts out some really interesting robotic projects that focus generally on assistive humanoids and intelligent robotic systems. This time, they wanted a robot that could vary its locomotion method by the situation. Who wouldn't want a drone to be as versatile as possible? Flying is great but isn't always feasible; rolling is nice, too, but you can't do that in water, etc.
MUWA, the Multi-field Universal Wheel for Air-land vehicle with quad variable-pitch propellers, tackles this issue rather elegantly and relatively simply. By using variable pitch rotors instead of the typical fixed-pitch versions that most quadcopters use, the students have gained additional control allowing the system to roll along the edge of its wheel-shaped body. Not only this, but the body is bouyant, so the vehicle can float on the top of water as well.
According to an article at IEEE Spectrum, the variable pitch propellers can shift up to 20 degrees, enabling its unique ability to stand on edge and roll. At first glance this may not seem like that useful of a feature, but it is easy to imagine scenarios where this might be important. Imagine trying to navigate inside a building where the chances of finding doors always propped wide open enough to fly through might be rare. Rolling allows the "footprint" to be reduced enough to fit through gaps that would be too small for humans. Rolling also uses much less energy as it doesn't have to support its weight in the air constantly.
At some point, you may be able to find more information on the University's website for the lab, but right now there is no mention of MUWA.
This design does seem quite nice. I immediately thought of the Gimbal, the crashing robot we covered recently, but quickly realized that even though the Gimbal can both fly and roll, it can not change its footprint, because it is a perfect sphere.