[convolvatron]

that is a really great encoder trick. I wouldn't have thought it was that good, but it clearly is.

[Animats]

What their video demonstrates is mostly same-direction repeatability, not absolute static accuracy. They can correct for with backlash at individual motors, but not slop or bend in the linkages.

This uses DC motors. If you use modern 3-phase servomotors, you know more of what the motor is doing.