September 15, 2014
Well, we knew it had to happen someday. A DARPA-funded robotic cheetah has been released into the wild, so to speak. A new algorithm developed by MIT researchers now allows their quadruped to run and jump — while untethered — across a field of grass.
The Pentagon, in an effort to investigate technologies that allow machines to traverse terrain in unique ways (well, at least that’s what they tell us), has been funding (via DARPA) the development of a robotic cheetah. Back in 2012, Boston Dynamics’ version smashed the landspeed record for the fastest mechanical mammal of Earth, reaching a top speed of 28.3 miles (45.5 km) per hour.
Researchers at MIT have their own version of robo-cheetah, and they’ve taken the concept in a new direction by imbuing it with the ability to run and bound while completely untethered.
MIT News reports:
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.
“Many sprinters, like Usain Bolt, don’t cycle their legs really fast,” Kim says. “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.”
Kim says 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.
“Most robots are sluggish and heavy, and thus they cannot control force in high-speed situations,” Kim says. “That’s what makes the MIT cheetah so special: You can actually control the force profile for a very short period of time, followed by a hefty impact with the ground, which makes it more stable, agile, and dynamic.”
This particular model, which weighs just as much as a real cheetah, can reach speeds of up to 10 mph (16 km/h) in the lab, even after clearing a 13-inch (33 cm) high hurdle. The MIT researchers estimate that their current version may eventually reach speeds of up to 30 mph (48 km/h).
It’s an impressive achievement, but Boston Dynamics’ WildCat is still the scariest free-running bot on the planet.