[![](https://spectrum.ieee.org/media-library/wide-angle-close-up-picture-of-a-silver-quadrupedal-robot-with-red-3d-printed-boots-standing-on-a-foam-pad-with-a-ladder-in-the-background.jpg?id=27656568&width=4032&height=3024)](https://spectrum.ieee.org/mini-cheetah-robots-feline-skills)

^{( October 14, 2021; IEEE Spectrum )}

Falls being bad is not a problem unique to robots, and it's not surprising that quadrupeds in nature have already solved it. Or at least, it's already been solved by cats, which are able to reliably land on their feet to mitigate fall damage. To teach quadrupedal robots this trick, roboticists from the University of Notre Dame have been teaching a Mini Cheetah quadruped some mid-air self-righting skills, with the aid of boots full of nickels.

Cats manage to land on their feet by curving their back and twisting in a way that conserves angular momentum. Figure skaters control the speeds of their spin using the same principle. This is more challenging for a *Cheetah* robot, though, because the spine is rigid and the legs are engineered to be light-weight. The boots full of nickels give the legs the weight they need to solve the problem, and a neural network that's trained in a simulated environment lets it choreograph the motion in a fraction of a second. Here's a video of the robot in action.
Read the rest from IEEE Spectrum: [Boots Full of Nickels Help Mini Cheetah Land on its Feet](https://spectrum.ieee.org/mini-cheetah-robots-feline-skills) **_Reference_**: - [Mini Cheetah, the Falling Cat: A Case Study in Machine Learning and Trajectory Optimization for Robot Acrobatics](https://arxiv.org/abs/2109.04424) - ( September 9, 2021; arXiv; [Vince Kurtz](https://wireless.nd.edu/people/current-students/vincent-kurtz/), [He Li](https://www.linkedin.com/in/he-li-8915a6206/), [Patrick M. Wensing](http://sites.nd.edu/pwensing/), and [Hai Lin](https://www3.nd.edu/~hlin1/) ) ---

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