Parallelogram based leg design

So,  I've been watching James Bruton's build of the GNK droid on his Patreon campeign.  I was quite impressed with it and I think he has some great ideas.  Turns out parallelograms are an interesting choice for legs. By stacking 2 parallelograms on top of each other you can create a leg with a hip, knee and ankle.  Regardless of the angle of each of the joints, the orientation of the hip and knee and ankle will always be parallel to the ground.  Pretty awesome.  So..  I had some 3/4" PVC pipe hanging around and a few worm gear motors to play around with.  After a few 3D printed parts to pull things together.. I have my first movements!


I'll update as the build goes on.. just wanted to share with the community a bit more about the direction that I'm going with the InMoov legs..

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pedrosenarego's picture


Nice one kwaters!!! do you know any video where we can see this already working?




ambroise's picture

leg amby

hello guys i see your idea leg

i am working to build to leg

you can see my idea here


it is my idea for knee

MdG_NL's picture

18Amp Servo driver (DC motor based)

Hi Kevin,

Here the info which I sended yesterday via the shoutbox:


MdG_NL: it's servo electronic which can handle 18Amp !

MdG_NL: this can be interesting for your legs:
kwatters: @mdg, does it use pwm to control and a separate pot for feedback? hardware controller for dc motors to make your own servo??
Yes, it works like a normal servo, it's just the servo-driver part with a external potentiometer.
It looks it's a 10Kohm potentiometer, I will check it later this day. (I've one set @ home :) )
You can change this for a better potentiometer.