Whether they use wheels, treads, or even legs, robots often have trouble extricating themselves from situations they may encounter on a space mission.
Their design can also prevent them from easily navigating around certain obstacles. The chances of hitting a roadblock only increase when human control is removed, as in the case of autonomous robots. Hopping robots inspired by the clumsy jumping of grasshoppers could prove to be the answer to giving robots unprecedented mobility for exploring other planets, gathering battlefield intelligence, and assisting police during standoffs or surveillance operations.
The hopping robots, developed by researchers at the Department of Energy’s Sandia National Laboratories, use combustion-driven pistons to make leaps as high as 20ft. When the combustion chamber fires, a piston punches the ground, propelling the hopper into the air.
One of the Sandia hopping robots is contained inside a grapefruit-sized plastic shell shaped like an egg so that the hopper rights itself after each jump with the piston facing towards the ground, but slightly askew. A pre-programmed microprocessor inside the hopper reads an internal compass, and a gimbal mechanism rotates the offset-weighted internal workings so that the hopper rolls around until it is pointed in the desired direction.
The tiny hopper jumps about 3ft in the air and 6ft from its starting point on each jump and, theoretically, could last about 4,000 hops on a single tank of gas, which is about 20g of fuel. Each hopping cycle is about five seconds. Another hopper, about the size of a coffee can, is able to jump 10-20ft in the air and theoretically could achieve 100 hops on a tank of fuel.
Rush Robinett of Sandia’s Intelligent Systems and Robotics Center (ISRC) conceived the idea of a hopping robot as he was catching grasshoppers to use for trout fishing. “I noticed they jump around in a random fashion, hit the ground in an arbitrary orientation, right themselves, and jump again,” he says. “I said to myself: ‘I can make a robot do that.’”
“Most mobile robots are designed to steer directly to a spot very efficiently,” says ISRC senior scientist Barry Spletzer. “But over long distances you don’t need that kind of precision. With a hopper you have time to make corrections after each jump, so it doesn’t need to steer while it’s the air. Once we determined that semi-random mobility was OK, we knew a hopper was possible.”