Driving over smooth ground using wheels is one of the most efficient forms of locomotion possible. It takes relatively little power to keep a wheeled vehicle moving across flat ground, particularly if friction and drag can be reduced. But smooth, flat ground isn’t always available, which is one reason why drones have become so popular. Unfortunately, drone flight is very inefficient and requires a great deal of power. That’s why researchers from Israel’s Ben-Gurion University of the Negev Bio-Inspired and Medical Robotics Lab have developed a robot that can drive and fly.
The benefits of this robot, called FSTAR (Flying Sprawl-Tuned Autonomous Robot), are substantial. In its drone configuration, it can fly over rough terrain or to reach elevated areas. Once it arrives at suitable terrain, it can transform into a wheeled robot to drive efficiently. Each of the rotors and wheels is mounted at the end of an arm, and the angle of that arm can be changed to switch between the flying mode and driving mode. While its driving, that arm angle can also be adjusted to squeeze through a narrow opening, fit under a low overhang, or travel over rougher terrain.
A robot that can drive and fly is hardly a new concept, but FSTAR stands out because the same motors are used for both modes. Those motors are the kind of brushless DC motors that are common among drones, but they also simultaneously drive the robot’s wheels. That does mean that the wheels are turning while the robot is flying, and that the rotors are spinning while it is driving. But the wheels don’t seem to affect flight performance much, and the rotors are spinning too slowly while driving to provide any lift. For now, FSTAR is just a 3D-printed prototype, but this style of robot could eventually be very useful in search and rescue operations where the terrain can be unpredictable.