openDog Dog Robot #9 | Kinematic Model XYZ | James Bruton

openDog Dog Robot #9 | Kinematic Model XYZ | James Bruton

You can get your openDog merchandise from:

Part 9 of my openDog open source hardware & software Dog Robot. It’s now time to derive and calculate the inverse-kinematic model for the robot so we can make it perform useful movements around each foot.

My open source robot dog project. It includes everything from 3D printing to coding, including a lot of CNC cutting and installing all the electronics myself.

If you want your very own four-legged friend to play fetch with and go on long walks then this is the perfect project for you. This way a dog can literally just be for Christmas. The full CAD is available at the link below for anyone that’s keen to build their own.


No MacArthur grant yet. But while I’m still waiting by the phone for that call, maybe you might patronise me with your Patreon-age. Or, if you’re all out of digital cash just comment on one of my hilarious Instagram pics, pop me a Tweet or generally yell in my direction.


Huge thanks to my patrons, without whom my standard of living would drastically decline. Like, inside out Farm Foods bag decline. Plus a very special shoutout to Aleph Objects, Inc who keep me in LulzBot 3D printers and support me via Patreon.

Why not join my community, who are mostly made up of actual geniuses. There’s a Facebook group and everything:


Former toy designer, current YouTube maker and general robotics, electrical and mechanical engineer, I’m a fan of doing it yourself and innovation by trial and error. My channel is where I share some of my useful and not-so-useful inventions, designs and maker advice. Iron Man is my go-to cosplay, and 3D printing can solve most issues – broken bolts, missing parts, world hunger, you name it.

XRobots is the community around my content where you can get in touch, share tips and advice, and more build FAQs, schematics and designs are also available.


The majority of the music and SFX used in my videos is from Epidemic Sound

50 replies
  1. yadaroni
    yadaroni says:

    There are several similar projects that I’m aware of that people have done, but I’ve never heard of one person designing and building every aspect of such a build by themselves. Hats off to you buddy, this is some amazing work.

  2. Orbis92
    Orbis92 says:

    Thank you so much. Within minutes this is now my favorite youtube "series". I have to catch up and watch the older videos. Great work so far. I learned I lot from this kinematic video(s) so far

  3. Neil Gordon
    Neil Gordon says:

    Please would you tell us how many person-hours have been invested in Open Dog’s development so far, including those made by any other contributors to the project.

  4. defender yogo
    defender yogo says:

    Always apply golden ratio in design whenever possible 😀 And do tell us when it is going to fight the Boston BigDog

  5. JonEilertsen (HellsatanX)
    JonEilertsen (HellsatanX) says:

    Spot, the boston dynamics dog robot has another axis of movement, each leg can rotate horizontally around its own axis

  6. Matt Mars
    Matt Mars says:

    Fantastic project loving watching it 🙂
    Couple of tiny things.
    One, re code, it should all be easily scalable, so while your waiting on the new legs, why not just put in the actual leg length and run it, see how it goes , what can be learnt ?
    Also, I haven’t followed the maths, I like the , if it’s zero, make it .1, simple fix,
    But why not have, if it’s zero then out put correct value for this special case , else do normal calculations…
    (Just removes a tiny, glitch in the heart of the system:)
    (Auth ‘A Brief History of Timelessness’ )

  7. Julian HG
    Julian HG says:

    My OpenDog mug has arrived! it’s possibly the finest mug i have EVER drunk from. i will never drink from anything else, ever!

  8. Chase Quijano
    Chase Quijano says:

    I’m a freshman in high school and I just had a quiz on triangles, when I was studying for it I looked at the EXACT same website you did, pretty weird.

  9. Rashad Glover
    Rashad Glover says:

    I have all of the big dog photos in high-resolution from every possible angle . I 3-D scanned the original big dog and the first atlas robot for proportion purposes for a project that I was working on that I gave up on. If you need my files & my high resolution images from every possible angle let me know? my email is my name at Gmail.

  10. D.B.
    D.B. says:

    This looks a lot more menacing in real life! Had the pleasure to see it in action today at the tct show 🙂 Keep up the good work and thanks for the chat too!

  11. Christopher Paton
    Christopher Paton says:

    Amazing Work James, starting to build one myself but want to edit some of the cad. I’m using Solidworks and STEP files arn’t editable, is it possible to get a repo of each single part?

  12. Travis Piper
    Travis Piper says:

    This is going very well can’t wait to see what’s next for it! Maybe some type of claw at the front or something to pick up objects?

  13. Brain Mind
    Brain Mind says:

    Hi James, can you please tell me why you decided to go with ball screws for actuation rather than hydraulics? It seems to me hydraulics would be a cleaner design and have faster response times.


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