• MIT Biomimetic Robotics Laboratory members pose with the MIT cheetah robot in Killian Court. (Top row, from left) Deborah Ajilo, Negin Abdolrahim Poorheravi,John Patrick Mayo,Justin Cheung, Sangbae Kim, Shinsuk Park, Kathryn L. Evans, and Matt Angle. (Bottom row, from left) Will Bosworth, Joao Luiz Almeida Souza Ramos, Sehyuk Yim, Albert Wang, Meng Yee Chuah, and Hae Won Park.

    MIT Biomimetic Robotics Laboratory members pose with the MIT cheetah robot in Killian Court. (Top row, from left) Deborah Ajilo, Negin Abdolrahim Poorheravi,John Patrick Mayo,Justin Cheung, Sangbae Kim, Shinsuk Park, Kathryn L. Evans, and Matt Angle. (Bottom row, from left) Will Bosworth, Joao Luiz Almeida Souza Ramos, Sehyuk Yim, Albert Wang, Meng Yee Chuah, and Hae Won Park.

    Photo: Jose-Luis Olivares/MIT

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  • The custom, high-torque-density motors and amplifier

    The custom, high-torque-density motors and amplifier

    Photo: Jose-Luis Olivares/MIT

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  • The face of the MIT cheetah-bot

    The face of the MIT cheetah-bot

    Photo: Jose-Luis Olivares/MIT

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  • MIT cheetah-bot experiment in Briggs Field. (From left) Sehyuk Yim, Joao Luiz Almeida Souza Ramos, Wyatt L Ubellacker, Sangbae Kim, Xu Sun, and Hae Won Park.

    MIT cheetah-bot experiment in Briggs Field. (From left) Sehyuk Yim, Joao Luiz Almeida Souza Ramos, Wyatt L Ubellacker, Sangbae Kim, Xu Sun, and Hae Won Park.

    Photo: Jose-Luis Olivares/MIT

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  • The MIT cheetah-bot in Killian Court

    The MIT cheetah-bot in Killian Court

    Photo: Jose-Luis Olivares/MIT

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Bound for robotic glory

Run, Cheetah, Run

New algorithm enables MIT cheetah robot to run and jump, untethered, across grass. Watch Video


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Speed and agility are hallmarks of the cheetah: The big predator is the fastest land animal on Earth, able to accelerate to 60 mph in just a few seconds. As it ramps up to top speed, a cheetah pumps its legs in tandem, bounding until it reaches a full gallop.

Now MIT researchers have developed an algorithm for bounding that they’ve successfully implemented in a robotic cheetah — a sleek, four-legged assemblage of gears, batteries, and electric motors that weighs about as much as its feline counterpart. The team recently took the robot for a test run on MIT’s Killian Court, where it bounded across the grass at a steady clip.

In experiments on an indoor track, the robot sprinted up to 10 mph, even continuing to run after clearing a hurdle. The MIT 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.

“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.”

Kim says what makes the robot so dynamic is a custom-designed, high-torque-density electric motor, designed by Jeffrey Lang, the Vitesse Professor of Electrical Engineering at MIT. These motors are controlled by amplifiers designed by David Otten, a principal research engineer in MIT’s Research Laboratory of Electronics. The combination of such special electric motors and custom-designed, bio-inspired legs allow force control on the ground without relying on delicate force sensors on the feet.  

Kim and his colleagues — research scientist Hae-Won Park and graduate student Meng Yee Chuah — will present details of the bounding algorithm this month at the IEEE/RSJ International Conference on Intelligent Robots and Systems in Chicago.

See the MIT cheetah-bot in action, and learn how it works.

Video: Melanie Gonick/MIT

Toward the ultimate gait

The act of running can be parsed into a number of biomechanically distinct gaits, from trotting and cantering to more dynamic bounding and galloping. In bounding, an animal’s front legs hit the ground together, followed by its hind legs, similar to the way that rabbits hop — a relatively simple gait that the researchers chose to model first.

“Bounding is like an entry-level high-speed gait, and galloping is the ultimate gait,” Kim says. “Once you get bounding, you can easily split the two legs and get galloping.”

As an animal bounds, its legs touch the ground for a fraction of a second before cycling through the air again. The percentage of time a leg spends on the ground rather than in the air is referred to in biomechanics as a “duty cycle”; the faster an animal runs, the shorter its duty cycle.

Kim and his colleagues developed an algorithm that determines the amount of force a leg should exert in the short period of each cycle that it spends on the ground. That force, they reasoned, should be enough for the robot to push up against the downward force of gravity, in order to maintain forward momentum.

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.”  

In experiments, the team ran the robot at progressively smaller duty cycles, finding that, following the algorithm’s force prescriptions, the robot was able to run at higher speeds without falling. Kim says the team’s algorithm enables precise control over the forces a robot can exert while running.

By contrast, he says, similar quadruped robots may exert high force, but with poor efficiency. What’s more, such robots run on gasoline and are powered by a gasoline engine, in order to generate high forces.

“As a result, they’re way louder,” Kim says. “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.”

This work was supported by the Defense Advanced Research Projects Agency.


Topics: Biomechanics, Robots, Robotics, Algorithms, Research Laboratory for Electronics, School of Engineering, Defense Advanced Research Projects Agency (DARPA), Mechanical engineering

Comments

Removing the high-pitch noise from the gasoline engine makes this MUCH more friendly. Great job!

amazing..

Really MIT is this the best use of your time.....a project for Disney?

I bought 200 480 grain solid projectiles for my 458 SOCOM after reading this article. It's that unnerving.

Soon to be adapted by the military and eventually used to kill.

Thanks MIT.

It is nice to claim this robot as untethered but that in itself is not a new feat, it is how long it will run untethered... That is the key and there is no mention of that.

Have we learned nothing from sci-fi movies?
Bad bad bad idea folks.

It's the Decepticon, Ravage!

"This work was supported by the Defense Advanced Research Projects Agency."

Great, the Terminator is going to get its own pack of hunting cats (dogs next).

There are so many people that fully understand the cheetah, that live in the cheetah areas, and also realize that cheetahs run fast for a short time, not a long time. 30 mph is not very fast, and you need to look at animals that run fast for a long time. Also employ some people from the third world that are out there and understand it. You at MIT are a bunch of instant experts, it will take you 20 years to figure out, what some third worlder already knows. Instant experts from MIT and other college boy places abound and they are always so amazed at what to many to count third worlders already know. When working in the third world, as I have on over 16 occasions, I am no longer amazed at meeting people with iq's above 180, the problem is there are few if any opportunities, so these very smart people, are just farmers, fisherman, hunters, whatever. Get real MIT instant experts, utilize the people that already know.

"Our robot can be silent and as efficient as animals."

At 30 mph, they're nowhere near as efficient as animals.

Coming soon to subjugate you.

So none of your brilliant boys and girls ever read Fahrenheit 451? Or you did and just couldn't help yourselves.

Or you could just ride a horse.

Can it turn?

Weak!

Very cool!

As a fellow engineer I understand just how difficult this is. Congrats!

Just the first step in eventually building a terminator. Skynet baby...

Yeah - I'm thinking since DARPA funded the project that transportation is NOT what they have in mind for this thing.

I like GOD's version better. Call me when it can catch a gazelle convert it's flesh into new muscles. reproduces itself and doesn't need to be plugged in to a wall socket for two hours.
Oh never mind, I'll be in eternity praising my Lord Jesus Christ by then.

This might not end well...

Hmmm. this has already been done a couple years ago. How is it they are saying this is new and never been done?

Are you Sarah Conner?

Humans will soon be targets of these robots. When they start shooting guns watchout.

Very cool. Congratulations. I will be interested to see how far the cheetah emulation can be taken.

Coming soon to a police department near you.

Now let's see it turn.

Absolutely Amazing!

I love the caption "Actual Cheetah" at 1:04 like we would confuse it with their robot! lmao

The robot is cool and shows promise, but it isn't that good yet.

Cool.

Interesting, but can it kill?
Otherwise, you are wasting taxpayers money.

Gotta change that background music. It makes this sound like something cheezy when it's really all pretty interesting.

MIT Students: Great work. Can you recover the IRS's emails for them, too?

Of course this new technology has, "military weaponization" written all over it.

Can you say, "Skynet", Cyberdine Systems", or "Terminator"?

Bow to your new cheetah overlords.

never thought i would live to see robots move life like--- or a computer. that could be made, that would do actual reasoning for itself --- now both are here. the terminator movies plot seemed so stupid to me--at the time--- but that was yesterday

You are not allowed to play cards in Africa.
.
.
.
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Too many cheetahs.

How about a Thorium engine?

Terminator was a warning folks.

So what is the point of all this stupidity? So we can have robots take over the world some day?

Nobody likes a cheetah.

For a second, I thought Cheeto-bot.................DAMMIT! GET ON THAT NOW MIT(at least it couldn't be used as a weapon.......yet).

Can we train them to eat democrats?

It's cool but needs to have flex in its spine like a real animal. It runs like it has a bad back. They are definitely on to something here.

An incredible accomplishment....but I know danged well these things will be used by humans, against other humans. People simply can't help themselves from exerting power over another. Wow things are REALLY going to get bloody soon....I mean much more than today

Very cool. Congrat's to the development team. Amazing. Now let's see it chase fast prey as well.

Cheetahs might be able to accelerate to 60 mph in just a few seconds, but after a quarter mile or so they'll be back to a crawl. Horses are fastest over any reasonable time or distance.

Is this a replacement for the Cheetos Cheetah? Not cool enough.

I only count 3 women. Isn't that Intelligence Inequality?

Nice, but where do you mount the kegerator?

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