Jaki ma udzwig ten robot. Da się nim przenieść powiedzmy lekarstwa, albo wodę? wystarczyłby np. 2 litry wody + kanapka. Wtedy można było by to coś wykorzystać do transportu a ludzie zapewne chieli by zając się programowaniem. Gotowe moduły mógłbys sprzedawać jak Józef Prusa swoje drukarki

Amazing project!  Are you planning on making the models available at some point?  I'd love to experiment with the design.

Please read the "Files:" section of the Description

I really like your design. Do you have any posts I could read about why you chose to use capstans over wobblers?

Wobblers?! 

Haha, it's a funny name I've heard is slang for cycloidal gearboxes, another small way to get a big reduction. I know that harmonic drives (which now sums up the 3 compact low-to-zero backlash gearboxes I know of) can be annoying due to the constantly changing flexion of one component, which can drive up costs. I think yours is the first capstan quad I've seen, and I'd love your thoughts on why capstans over cycloidal drives. I can send you some links to cycloidal drive quads if you haven't seen that design.

@David Greenberg You could compare against many things, cycloids aren't even a worthwhile comparison cause the range of reduction ratios they offer has very little overlap with what u get with capstans. First the ratio - you need less than 1:9 to have a proper Quasi Direct Drive actuator, to achieve the torque transparency required to apply advanced controllers like the MIT mini cheetah one. (this is not true for all scales, but at this scale it is). So here cycloids are out of question already - just because of the ratio - they are also bad for many other reasons I won't get into. The only worthwhile comparison is to the planetary gearboxes in the actuators used in MIT mini cheetah and all similar bots. A planetary reducer is a better solution, it might be the best available - but only if you can fabricate your bot in metal. I decided to limit myself to 3D printing - and when we consider 3D printed planetary gearboxes - they would need to be really bulky, contain a lot of bearings and would wear quickly, plus will never be truly 0 backlash. A Cable drive can be as efficient as a planetary (also as torque transparent) - and at the same time, it does not suffer because of the limits of 3D printing. There are no contact spots that are under loads as high as the loads on teeth of a planetary gearbox. Thanks to this a highly torque transparent yet lightweight and robust to high dynamic loads can be manufactured using only 3D printing.

Your reasoning makes a lot of sense. If you have any references on other downsides of cycloids, I'd be interested in reading, especially as to whether the downsides are fabrication or control related.

@David Greenberg the downsides are mainly low efficiency, and high massif higher efficiency is attempted (you could easily fit 50 bearings into a cycloidal gearbox if you want all contact to be rolling contact). I have experience making cycloids, they are good for robotics, even cobot-style robotics - but legs need much more than that in terms of torque transparency.

This is amazing! I had a very similar design in my mind for a long time, but never had the time to realize it. I'm an engineer working in haptics where capstan drives are used quite often and I am conviced that they are very nicely applicable to quadruped robots. So I am really stoked to see your amazing implementation of this kind of transmission. Looking already forward to seeing your next progress update! 

really cool work . !i wish i could afford to make one :(

I did my best to go as low with the price as i could, while still making a true high performance BLDC based quadruped. Below ~2400usd you need to go with hobby servos or dynamixels. There are also cheaper bldc options if you're willing to solder your own ESC's - take a look at the open dynamics initiative 

Nice design, I appreciate the attempt to keep it affordable.

Thanks :D was trying my best!