Shape of things to comeArmy heli-UAV hops to avoid obstacle trouble
The U.S. Army funds development of a hopping rotochute — a UAV designed to travel deep into obstacle-ridden spaces such as caves and rubble-laden buildings to video what it finds
We do not know how many of our readers would remember Weebles, the toy figures that wobbled but never fell down. Paul Marks writes that if you crossed one with a miniature helicopter, you would end up with something like the U.S. army’s forthcoming reconnaissance craft: the hopping rotochute.
This self-righting probe is designed to travel deep into obstacle-ridden spaces such as caves and rubble-laden buildings to video what it finds. It is being developed for the Army Research Lab in Aberdeen, Maryland, by Eric Beyer and Mark Costello, two robotics engineers at Georgia Institute of Technology in Atlanta.
The army wants this capability because today’s military robots, which run on small tank-style tracks, cannot cope with irregular surfaces and obstacles such as rubble or boulders. “They usually have trouble and get stuck with even low obstacles and walls a couple of feet high,” says Costello. Small helicopters are one alternative, but continuous flying drains the batteries fast.
So their answer — which Costello freely admits is Weeble-inspired — is a rotor-powered, bottom-heavy, self-righting vehicle that spends most of its time on the ground, thus conserving battery power. Instead of flying around, it hops, using a pair of contra-rotating rotors (to avoid the need for a tail rotor) mounted on an aluminum base. All this is encased in a spherical cage made of strong carbon-fiber spars.
To steer in flight, the robot swings a weight to tilt in the direction it needs to hop. Whichever way it lands, the weight of the base rights it.
Might repeated hopping harm the craft? “From a crashworthiness point of view this concept looks perfectly feasible,” says a spokesman for the Impact Center at Cranfield University in Bedfordshire, United Kingdom. “There should be no problem with the vehicle surviving hundreds of impacts, which is roughly equivalent to dropping a mobile phone from waist height.”
-read more in Walton R. Williamson et al., “Fault Detection and Isolation for Deep Space Satellites,” Journal of Guidance, Control, and Dynamics 32, no. 5 (September–October 2009) (DOI: 10.2514/1.41331)
