Thread by @chubicki

Indeed I have! Theo Jansen's walking sculptures actually have strong parallels to a popular control method for making #robots walk.

Thread:

https://twitter.com/Gretchen6205/status/1117159687567208448

Theo Jansen (@StrandBeests) is a Dutch Artist who builds amazing mechanical art pieces called "kinetic sculptures." When the wind spins the crank on the side, the mechanism walks! Jansen carefully arranged and sized the sculpture's connecting sticks to make the walking motion.

But if you want a different walking motion, you need a whole new mechanism! That's impractical for robots. So instead of connecting physical sticks, as Dr. Jessy Grizzle from @UMRobotics shows, you can connect them virtually using motors & software, or "Virtual Constraints." [1]

Grizzle and colleagues @EECSatMI showed that this "virtual constraint" idea can be applied really broadly. They used the bipedal #robot, MABEL [2], to show they could control it to walk, run, and even recover from unseen obstacles. [3,4]

The *mathy* name for this idea is "Hybrid Zero Dynamics" or HZD. It's key for lots of control algorithms for walking robots [5,6] & a lot of my own work, too [7]. So the parallels between clever mechanisms (like Jansens') and algorithms are strong and interesting!

End thread!

References:
[1] ieeexplore.ieee.org/abstract/docum…
[2] ieeexplore.ieee.org/abstract/docum…
[3] bit.ly/2ID9Y8H
[4] ieeexplore.ieee.org/abstract/docum…
[5] arxiv.org/pdf/1809.07279…
[6] ieeexplore.ieee.org/abstract/docum…
[7] ieeexplore.ieee.org/abstract/docum…

Addendum... and it's not just for robots. Now, researchers are also developing HZD for control of robotic prosthetic limbs and exoskeletons.

[1] ieeexplore.ieee.org/abstract/docum… @doctorBobG
[2] ieeexplore.ieee.org/abstract/docum… @AMBER_lab
[3] ieeexplore.ieee.org/abstract/docum… @ayonga @ayush1292 @OmarHarib