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Here's next week's video, early for Patrons. This one goes out publicly on Tuesday 8th.

This is something I've been meaning to try for a while, and it's been suggested a few times. There will hopefully be an openDog V3 with Cycloidal drives in though at some point.

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Previews only

Constant-Torque Spring-Balanced Actuator - PREVIEW VERSION

I've often been asked about adding springs to openDog to balance the actuators and assist with power saving. However, this would also make it harder to take steps as the feet lift off the ground. But what if we could develop a constant-torque spring-balanced actuator which didn't require more and more force the more the spring stretches? You can support me on Patreon or buy my Merchandise: *************************** Patreon: https://www.patreon.com/xrobots Merchandise: https://teespring.com/stores/james-bruton *************************** Affiliate links - I will get some money of you use them to sign up or buy something: *************************** Matterhackers 3D printing supplies: http://www.matterhackers.com?aff=7500 Music for your YouTube videos: http://share.epidemicsound.com/xrobots *************************** Other socials: *************************** Instagram: https://www.instagram.com/xrobotsuk Facebook: https://www.facebook.com/xrobotsuk/ Twitter: https://twitter.com/xrobotsuk *************************** CAD and Code for my projects: https://github.com/XRobots 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 Lulzbot, Inc who keep me in LulzBot 3D printers and support me via Patreon. HARDWARE/SOFTWARE Below you can also find a lot of the typical tools, equipment and supplies used in my projects: Filament from: https://www.3dfuel.com/ Lulzbot 3D Printers: http://bit.ly/2Sj6nil Lincoln Electric Welder: https://bit.ly/2Rqhqos CNC Router: https://bit.ly/2QdsNjt Ryobi Tools: http://bit.ly/2RhArcD Axminster Micro Lathe: http://bit.ly/2Sj6eeN 3D Printer Filament: http://bit.ly/2PdcdUu Soldering Iron: http://bit.ly/2DrNWDR Vectric CNC Software: http://bit.ly/2zxpZqv Why not join my community, who are mostly made up of actual geniuses. There’s a Facebook group and everything: https://www.facebook.com/groups/287089964833488/ XROBOTS 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.

Comments

Philip Brechler

Simple fix for the problem of holding power! Question: Could you maybe make them more compact by using a circular spring similar to what watches use to store their energy?

XRobots

It's possible, although we'd still need that exponential part in there somehow. Probably a smaller cam and an stronger meal spring would be my first change.

Anonymous

A really good video James, a brilliant explanation of the problem, the steps to understand and solve it and the ultimate test on the robot.

John McCormick

Now the robot dogs legs have tendons like a real dog

Anonymous

I'm impressed how well you managed to retro-fit these without a full rebuild.

Anonymous

I'm looking forward to the return of open dog.

Andrew .

Maybe rather than constant force, what you actually want is a lot of force when the legs are extended more (hitting the ground, offsetting robot weight) and less force when the legs are contracted (taking a step as easily as possible)? Not sure... just a thought

Thomas Messerschmidt

1. Very clever idea! I would have never guessed that the part that you had posted was to be used for reducing the motors’ power consumption. I have a friend who built a life-size Wall-E and I was at his house while testing the drive unit rolling across his lawn. It was drawing quite a few amperes as well—over 150–but that of course was with treads. 2. Someday you should have your bipedal humanoid robot take your quadrupedal dog robot out for walkies! 3. On another topic, have you seen Will Huff’s drink serving robot? I found it impressive.

XRobots

I think the cams could have been smaller, and have tighter metal springs, but it's ok for the demo!

XRobots

I have new motors on the way for V3 with Cycloidal drives, it might be a little while before it's all together though.

XRobots

I guess it would be easy enough to change the cam profile for that. It all depends how long the legs are when its standing still, at the moment they can be any length and the force is always constant.

XRobots

I'd like to do another biped, but probably balance-assisted with spinning gyroscopes - I'll do a one-wheeled balancer first. Yep I follow Will's stuff - looking pretty good!

Anonymous

another great video and explanation James. 200+ amps though - wowsers!