Located along the Charles River in Cambridge, Ma, the Massachusetts Institute of Technology is one of the top private research universities in the world.  One of the areas MIT is perhaps best known for is their advanced science, engineering, and robotics research labs.  One such lab at MIT is the Biomimetic Robotics Laboratory directed by Professor Sangbae Kim, who is also an Associate Professor of Mechanical Engineering at MIT.  In the Biomimetic Lab Professor Kim’s research focuses on robot design based off of the biology of animals.  Recently a project from his lab received a lot of media attention because of a video they posted featuring robotic cheetahs playing soccer.

The four limbed robots they designed were inspired by Sangbae’s favorite animal the cheetah, and the lab has been working on these robots for a while now.  In fact, there have been three versions of the MIT Cheetah robots including the latest model the MIT Mini Cheetah.  The early models were large, complex designs.  Whereas the Mini Cheetah weighs only 20lbs and is built with off the shelf parts.  The students behind the Mini Cheetah, Benjamin Katz and Jared Di Carlo, used motors and parts that were meant for drones to build the Mini Cheetah.  This led to a light weight, robust, highly maneuverable, and inexpensive final product.

A lot of programing went into the design of these drone like robots.  The Mini Cheetah is powered by 12 coordinating drone motors that allow each of the limbs to work independently and in tandem.  If something goes wrong with one of the motors or limbs, they can easily and cheaply be switched out.  Katz compared the build of the Mini Cheetah to Legos, you just quickly snap and go.  Algorithms were written that allow the Mini Cheetah to make more than 30 decisions per second.  These algorithms provide the drone with it’s flexibility and maneuverability.  The Mini Cheetah can run up to 5mph forwards, backwards, and laterally.  If knocked to the ground the robot can automatically flex or bend it’s joints to flip over and right it’s self.  One of the reasons they decided to build the Mini Cheetah according to Katz is that, “it makes it so easy to experiment and just try crazy things, because the robot is super robust and doesn’t break easily, and if it does break, it’s easy and not very expensive to fix.”

One of the experiments they decide to test out on the Mini Cheetah was to see if it could do backflips.  First they tested out the robot’s speed by racing it through hallways and over uneven ground.  Then they wrote an algorithm to have the Cheetah showcase it’s range of motion and flexibility with yoga like stretches and poses.  This was followed by the program to have the robot flip back over after being knocked down.  All of this led Katz and Di Carlo to wonder if the Mini Cheetah could take on the greater force and technicality of performing a backflip.  Katz said, “We thought it would be a good test of robot performance, because it takes a lot of power, torque, and there are huge impacts at the end of a flip.  The first time we tried it, it miraculously worked.  This is super exciting.  Imagine Cheetah 3 doing a backflip — it would crash and probably destroy the treadmill. We could do this with the Mini Cheetah on a desktop.”

In the video Katz released you can see the Mini Cheetahs in action as they prance around a leaf strewn, grassy field.  The robots run around each other, travel with a soccer ball, pass the ball back and forth, hop around, get knocked over and flip back up, and of course complete 360 degree back flips.  The min robots have a cuteness about them as they play.  It’s hard to remember that they are machines being controlled through detailed computer programing because they almost look like a group of strange puppies playing together.

Katz went on to compare the Mini Cheetahs to dogs himself as he expressed his hope to have more of them built and shared with other robotics research labs.  He said, “Eventually, I’m hoping we could have a robotic dog race through an obstacle course, where each team controls a Mini Cheetah with different algorithms, and we can see which strategy is more effective.  That’s how you accelerate research.”  From the video it seems like the work being done in Professor Kim’s lab is more recreational than educational, but that is far from the truth.

Countless hours of research and development went into each facet of designing the Mini Cheetah.  With each experiment the robot progressed.  Katz was so impressed with the Mini Cheetah’s ability to flip that they are now working to find an even greater challenge for the robot.  He went on to say, “We’re working now on a landing controller, the idea being that I want to be able to pick up the robot and toss it, and just have it land on its feet.  Say you wanted to throw the robot into the window of a building and have it go explore inside the building. You could do that.”  And that is how you transition a tool that looks like just a really cool toy robot into an actionable working tool.  Ideally the Mini Cheetah could one day be used the way drones are to inspect areas for safety.  But there is nothing wrong with having a little robotic fun getting to that goal.

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