We have seen robots climbing stairs while avoiding obstacles, and opening and holding doors for their robo-peers, but Mini Cheetah, MIT’s new droid is the very first four-legged robot able to do a backflip!
Mini Cheetah, the Lego-like gymnast
Researchers at MIT’s Department of Mechanical Engineering are constantly working on stuff that never fails to impress us. This time it is a rather small and lightweight four-legged robot. Mini Cheetah weights only twenty pounds, which might be a key element behind is capabilities.
The flexible quadruped runs faster than an average human walks; it swings and bends like a yogi and uses its rotating limbs to maintain perfect balance. Additionally, it emerges fast with a kung-fu-esque motion after being kicked to the ground performing an elbow-swing maneuver.
Mini Cheetah is driven by three identical electric motors on each of its legs. Using off-the-shelf parts in the building of the robot helped to keep its cost low, thus, in case of a malfunction or accident for that matter -gymnastics is a dangerous activity- each element of the robot is easily replaceable.
‘You could put these parts together, almost like Legos’, says lead developer Benjamin Katz. He designed the motors appropriating widely available tech used initially in drones. The three motors per legs design enable a surprisingly big range of motion.
Thanks to its high torque and low weight, Mini Cheetah is fast and dynamic while maneuvering, and it handles anything rough terrain can throw at it without breaking a limb or a gearbox.
‘When it's running, its feet are only on the ground for something like 150 milliseconds at a time, (…) it can do really dynamic stuff like jump in the air with every step, or run with two feet on the ground at once.’ - technical associate Mr. Katz describes Mini Cheetah’s skillset still himself being excited about what he has just developed.
Experiment, and let others do the same!
Mr. Katz and his co-author Jared Di Carlo (an undergraduate at MIT) took a class together, taught by EECSProfessor Russ Tedrake which inspired them to try to program the performance of a backflip.
So they optimized the Mini Cheetah’s program specifying all the torques of each individual motors, as well as the period between the start and stop on every twelve motors, and, as Katz remembers: ‘The first time we tried it, it miraculously worked!’
Katz and Di Carlo built Mini Cheetah in the lab of associate professor Snagbae Kim. The researchers will present their work at the International Conference on Robotics and Automation in May. They are building more Mini Cheetahs in order to loan them out to other research labs. Professor Kim believes in the open platforms and their potential to accelerate research.
‘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.’
The young inventors never stop going beyond. They are currently working on a landing controller so that the robot would be able to steadily land on its feet after a big throw.
‘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. - said Mr. Katz.