Home Creators Posts Import Register Favorites Logout
haven't archived this post yet. have a subscription? use the importer!

Content

Here's next week's video, early for Patrons. I've carried out torque tests using an ODrive, and more resilience testing for the Cycloidal Drive. Pretty sure the Cycloidal Drive is the best way to go ;-)

Files

Previews only

Testing: Cycloidal vs Harmonic Drive 3D Printed Reducers

Over the last few weeks I've built two versions of Cycloidal Drive Reducers, and one Harmonic Drive / Strain Wave Reducer. This video is about testing both using an ODrive and an encoder on the motor so we can energise the motor coils correctly and apply motor holding power. I also want to make sure that the Cycloidal Reducer is tough so that is subject to some extra resilience testing. My Cycloidal Reducer will get developed further, probably removing the bearings, so we can use it in the next version of openDog. 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

XRobots

It's pretty tricky in Fusion - Levi is showing it by plotting a rotating circle rolling around a the bigger circumference, which is a similar approach to the one I'll probably use.

Scott Cress

Great video James! Loved seeing all the technical calculations. If I ever get a chance to build one I wonder how much a 15 or even 20 to 1 gear reduction could support? And how back-drivable it would be. You had near 50lbs of support on your "leg"

Anonymous

Looking good, still dreaming of the day OpenDog is ready to build! Thanks much

XRobots

Generally Quasi-direct drive is considered to be 10:1 or less as far as I understand it, although I guess you could go higher, but it might have less effect as a 'virtual spring'. I think 10:1 is more than enough for now considering the tests.

XRobots

I featured Paul Gould in part 1 ;-) I'd be concerned about what happens at high velocity and high torque though - when a 30kg robot jumps on the ground etc.

Anonymous

I *think* the contact with the outer pins is "rolling" (I'm not a mechanical engineer) so no sliding friction/torque parallel to contact. This property would lead to a nice cost/weight saving as well as making 3D printing more realistic.

XRobots

You are correct - if the Cycloidal disc is designed correctly then it should roll and not slide. I may try it, but I still feel better with even nylon bushings.

Anonymous

If you are brave, you could put your finger on one if the outer bearings in your existing design and feel if it wants to rotate. But that thing looks like it could take off a finger, so...

XRobots

They do - I marked one with a pen and I can see it ;-) But my Cycloidal disc was heavily estimated.

F1777

Vesc 6 is more accurate and recently they released advanced sensorless startup which can provide pretty accurate position control with no sensors. Or of course very accurate with sensors. You can run an encoder with a vesc just like an odrive. They use vescs in robotics

XRobots

I need to check what the comparison is with the latest ODrive firmware which now support absolute positioning on startup with AS5047 (the motors just come on and work with no seek for the index signal) and also CANBus is now supported which will save some serial lines.

XRobots

Apparently if the cycloidal disc is designed correctly, the surfaces should roll over each other so there shouldn't be too much friction. I guess as long as the material is tough enough it should do, but I have various options to consider.

Anonymous

Folks may want to know there was a new version of a popular thingiverse bearing model uploaded yesterday and I'm going to eventually give these a try, I'm waiting for my motor and controller to get here. Is there a list anywhere that mentions the dimensions of the bearings used in your cycloidal drive James? Thanks! https://www.thingiverse.com/thing:4821342

XRobots

Thanks Daniel, the bearings are drawn in the CAD, but the small ones are 4mm id/12mm od, and the larger ones are 20mm/30mm