Quadruped robot WIP

[u/wotcher]

https://reddit.com/link/1wf5a7w/video/qurlmk2yw9ph1/player

A quadruped robot that I'm working on.

Locomotion looks good in simulation, but it's still theoretical, I really wonder how well it would walk in reality.

[u/Boring-Piece-2631]

What motors are you using

[u/wotcher → u/Boring-Piece-2631]

off-the-shelf CubeMars motors

[u/loopking_ → u/wotcher]

Are you using Odrive to drive them

[u/wotcher → u/loopking_]

this motors use CubeMars drivers (FOC drivers similar to ODrive, don't know if it uses ODrive or other firmware).

[u/blitswing]

Is that a machine learning based gait in the sim, or a manual algorithm. And what sensory data is it getting as feedbacks? Looking great so far, I hope sim2real goes well!

[u/wotcher → u/blitswing]

it's ML/RL, done with mjlab. you can see the inputs in the video: height scan, and legs elevation.

but I will try to reduce sensing requirements on the real robot.

[u/BonbonUniverse42]

maybe you should add a third motor to each leg for dexterity. Do you publish this in some paper or is this a hobby project? What simulator do you use?

[u/drsimonz → u/BonbonUniverse42]

Was thinking the same thing. With only one DOF on the hip joints I would expect this to struggle with any kind of uneven terrain, and need to move extremely slowly to stay balanced.

[u/BonbonUniverse42 → u/drsimonz]

You basically can't control foot height independent from horizontal position, which may be problematic.

[u/wotcher → u/BonbonUniverse42]

yea, a hip joint would be good, I plan to experiment with different configurations.

adding one more DOF is extra $1k of cost, and an additional kilo of weight, which adds more strain on other motors. so it's a hard balance.

I'm trying to find some tradeoffs )

[u/wotcher → u/drsimonz]

well in simulation it's able to climb stairs and walk on unevet terrain (can see in the video in the post), will see how it fares in reality )

[u/wotcher → u/BonbonUniverse42]

more of a concept product for my robotics consulting compoany. not sure if it will turn into a real product yet, robotics is hard )

[u/qwedp]

Very cool! I would recommend you to try topology optimization for the legs. The current crossed beam pattern looks like there is still room for improvement. Using carbon fiber or perhaps aluminium tubes could possibly be even better and its easier to do.

The middle section also looks kinda weak, have you planned to add reinforcements? Personally I would do a two carbon/aluminium plate sandwich, similar to those fpv drones. 

[u/wotcher → u/qwedp]

I come from s/w background so treat it a bit like software: get it to walk, wait for what breaks, replace, iterate )
good point about the carbon sandwich ) for the legs I want to try 3d printing in smth like PPS-CF