I’ve been looking for a new motor control project to tackle that is both interesting, and a bit more unique than another Ascento clone. Looking around, I was surprised at the current paucity of robots capable of more advanced juggling feats. There are quite a few that can manage 3 balls, and nearly none I’ve found that can manage more, with the exception of Nathan Peterson’s inclined ball roller. I figure that I have access to lots of factory second moteus controllers, which are capable of quite demanding control applications, so I should be able to put something together.

This is what I’ve got so far:

This is a single 6 DoF Stewart platform controlled by 6 moteus r4.11s with mj5208s acting as the servos. A pi3hat and power_dist are nestled inside a 3d printed hexagon. M4 push rods with tie rod ends connect the servo horns to the upper platform, which has an indent to “catch” the ball. At this point, all I’ve done is some simple open loop toss behaviors without any fine tuning or aiming. It can reliably catch and toss some 50g micro juggling balls up to around 30cm, and can throw (but not catch) up to around 80cm.

My intention is to first get this to be able to throw and catch at higher throws, then do some basic 1 hand patterns with 2 or maybe 3 balls. Once I get that working, then I’ll add in a second platform to make the second hand and see what I can pull off. I’ve got an rpi global shutter camera with the intent to do visual tracking of the balls if necessary, but we’ll see how accurate I can get the tosses just open loop first.

The hackaday project page with an overview is here.