Let’s get this out of the way first. Yes, the robot cheetah is a military-funded project, supported by the Defense Advanced Research Projects Agency (DARPA). So when the machines rise up and you see one of these things running you down with a lightweight machine gun mounted on its back, feel free to have a patriotic twinge of pride at what your tax dollars have accomplished.
The robot cheetah that Massachusetts Institute of Technology (MIT) researchers have developed with this defense money is a huge leap forward in robotic animal technology. You may have seen other running robots of this type, but those were noisy, clunky monstrosities powered by gasoline engines or tethers. The robot cheetah is a quiet, autonomous system that uses electric motors.
“Our robot can be silent and as efficient as animals. The only things you hear are the feet hitting the ground. This is kind of a new paradigm where we’re controlling force in a highly dynamic situation. Any legged robot should be able to do this in the future,” said researcher Sangbae Kim, an associate professor of mechanical engineering at MIT.
The robot cheetah runs at 10 miles an hour, one-sixth the speed of its real world counterpart. It can also jump hurdles up to 33 centimeters. The team hopes to get the cheetah running at 30 miles an hour eventually.
Real cheetahs gallop, which is an asymmetrical high speed gate where the legs move independently. The team chose to make their robot use a symmetrical bounding gait, where both the front legs bounce of the ground together, followed by the hind legs, because it was easier to model as a first step.
“Once you get bounding, you can easily split the two legs and get galloping,” Kim said.
The trick with to get the robot bounding at high speed was working out an algorithm that told it just how much force to apply in the split second its legs touch the ground.
“Once I know how long my leg is on the ground and how long my body is in the air, I know how much force I need to apply to compensate for the gravitational force,” Kim says. “Now we’re able to control bounding at many speeds. And to jump, we can, say, triple the force, and it jumps over obstacles.”
The robot’s light weight and ability to adjust the force of its running makes it more stable and better at handling rough terrain.
The robot is far from off the shelf parts. To make it do what they needed, the team used a high-torque-density electric motor, designed by Jeffrey Lang, the Vitesse Professor of Electrical Engineering at MIT, and also created custom designed legs.
Okay, okay, so I know this was designed as a weapon, but I’m really hoping it trickles down to civilian use, and that they make a model sturdy enough to carry people around. Who wouldn’t want to ride the back of a robot cheetah?