Stanford Pupper: low-cost quadruped robot

Re:Stanford Pupper: low-cost quadruped robot by Animats on Sunday May 03, 2020 @06:24PM (#23062388)

It's fun seeing these. As batteries and motors get better, they get more agile.

I'm disappointed that there's no force feedback. They're still using dumb PWM servos, which is a 1970s technology. There are better servos, from Dynamixel, where you get info back. There was a project called OpenServo [1] to smarten up dumb servos by developing tiny new controller boards for cheap RC servos. But that project seems to be defunct.

There are lots of good legged toy robots in the $300-$400 range, but without good feedback you can't do Boston Dynamics type stuff.

[1] https://hackaday.io/project/158267-openservo-20

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Re:Stanford Pupper: low-cost quadruped robot by NathanKau on Sunday May 03, 2020 @06:51PM (#23062547)

We've found you can actually do a lot with dumb servos and orientation feedback and get visually similar results to Spot. For instance, we get hopping, trotting, strafing, turning + strafing, walking. What it can't do is prancing or a flying trot. But we think it's totally worth it since a good-enough servo is around $20, while similarly sized torque-controllable servo (excluding dynamixels, which don't actually have torque control), runs about $400 each. DJI did actually come out recently with their M3508 and M2006 which we're starting to play with, and we think we can build a torque-controllable pupper for about $1.5k.

The main limitation I think for servo robots with kinematic (position-control) controllers is speed. We're moving around 0.8m/s max, while the new Unitree A1 is something like 3.5m/s.

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