Now, 'cheetah robot' that runs and jumps across grass

Researchers have developed an algorithm that enables their "cheetah robot" to run and jump, untethered, across grass.

MIT researchers' sleek, four-legged assemblage of gears, batteries, and electric motors that weighs about as much as its feline counterpart bounded across the grass at a steady clip and sprinted up to 10 mph, even continuing to run after clearing a hurdle.

The researchers estimate that the current version of the robot may eventually reach speeds of up to 30 mph.

The key to the bounding algorithm is in programming each of the robot's legs to exert a certain amount of force in the split second during which it hits the ground, in order to maintain a given speed: In general, the faster the desired speed, the more force must be applied to propel the robot forward. Sangbae Kim, an associate professor of mechanical engineering at MIT, hypothesizes that this force-control approach to robotic running is similar, in principle, to the way world-class sprinters race.

Kim said that many sprinters, like Usain Bolt, don't cycle their legs really fast and they actually increase their stride length by pushing downward harder and increasing their ground force, so they can fly more while keeping the same frequency.

The researcher said that by adapting a force-based approach, the cheetah-bot is able to handle rougher terrain, such as bounding across a grassy field. In treadmill experiments the team found that the robot handled slight bumps in its path, maintaining its speed even as it ran over a foam obstacle.

The researcher added that MIT cheetah's force profile can be controlled for a very short period of time, followed by a hefty impact with the ground, which makes it more stable, agile, and dynamic.