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Cycloidal Robot Actuator

by LoboCNC Apr 4, 2019
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Cool design, thanks for sharing.
I have experimented with CNC cutting cycloidal reducers, but not 3D printing them - Yet.
I wonder if 3D printing holes and adding metal dowel pins to the large outer ring would help make it smoother and last longer (plastic on smooth ground metal).
Also, any way to balance the high speed rotor to reduce vibration? I'm guessing one of the larger components of the vibration is coming from the mass of the set screw clamping the motor shaft. It would require scaling up to add counterweights (or move the set screw) to the "thin side" of the high speed hub. Alternately, could the hub be extended to add a counterweight slightly above or below (or both) the rotor?

Is there an encoder integrated into it?

That's a good idea! With a long robotarm you may have problems with the vibration !

Nice idea! Do you think these actuators would be superior to the ones you designed the six axis robot arm? Thanks

Right now, no. My initial test show that they aren't as efficient as the planetary drives. I've got 2 ideas up my sleeve, though. The first is to do a helical version of this cycloidal drive. This will help even out the variation in the pressure angle that you normally get with cycloidal teeth, and it'll probably also smooth things out in general. The second idea, for the planetary actuators, is to turn the lower ring gear into a flex spline (like with my planetary/harmonic hybrid). This will allow for tighter fitting gears but also keep everything from locking up over any small irregularities. And may the best drive win!

I noticed something odd messing with helical cycloids - they were backdrivable, they didn't "lock".

very nice job i want test it thank you

Does it have any backlash?

Yes, it does have some backlash, but that can be tweaked by adjusting the amount of eccentricity in the hub. There will always be a tradeoff between backlash and friction, though, when dealing with the relative inaccuracy of 3D printing.