REMEMBER Weebles, the toy figures that famously wobbled but never fell down? Well, if you crossed one with a miniature helicopter you鈥檇 end up with something like the US army鈥檚 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 , a pair of robotics engineers at Georgia Institute of Technology in Atlanta.
The army wants this capability because today鈥檚 military robots, which run on small tank-style tracks, cannot cope with irregular surfaces and obstacles such as rubble or boulders. 鈥淭hey usually have trouble and get stuck with even low obstacles and walls a couple of feet high,鈥� says Costello. Small helicopters are one alternative, but continuous flying drains the batteries fast.
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So their answer 鈥� which Costello freely admits is Weeble-inspired 鈥� 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 aluminium base. All this is encased in a spherical cage made of strong carbon-fibre spars (see diagram).
To steer in flight, the robot swings a weight to tilt in the direction it needs to hop (Journal of Guidance, Control and Dynamics, ). Whichever way it lands, the weight of the base rights it.
But might repeated hopping harm the craft? 鈥淔rom a crashworthiness point of view this concept looks perfectly feasible,鈥� says a spokesman for the Impact Centre at Cranfield University in Bedfordshire, UK. 鈥淭here should be no problem with the vehicle surviving hundreds of impacts, which is roughly equivalent to dropping a mobile phone from waist height.鈥�
