Alternatives to Strain Wave Gears?

[cj7hawk]

Hi All,

I'm looking to find/build small compact servo motors, eg, 80~200mm diameter, <100mm length, 200watts output, > 5Nm torque, 360 degrees / second... On the order of that kind of servo, while also ideally being lash-free, or at least with low lash.

I was looking at strain wave gears ( harmonic drives ) but these seem to cost around $1000 each, and most are solid centered, so would require an external motor.

I'm looking for similar ideas ( ratios > 10:1 in a single stage, up to 200:1 ) in a small size, with high efficiency ( > 90% minimum ), ideally few parts, and which can incorporate a motor and a reduction system within a very small size with a very high output power.

What alternatives to strain wave systems exist that are inexpensive, ideally can be built without needing a factory or expensive CNC equipment ( eg, 3D printed would be ideal ) and would be suited to large scale robotics?

All I can find presently is cascaded planetary systems, strain-wave drives, some 3D printed strain-wave drives ( that seem a little flimsy to ask for any serious torque ) and such.

Does anyone have ideas that they can send me for existing products that do this kind of function? What should I be thinking of? What have I missed considering? What designs address this requirement?

Any and all suggestions appreciated?

Thanks
David

 

[s.weinberg]

As you already mentioned, planetary gears are highly versatile. If you go with a more complex design, you can get quite a high reduction in a fairly tiny space.
Cycloidal gearing is another option you should explore.
Rumour has it, contrary to popular belief, that you can achieve fairly decent efficiency with a relatively low reduction worm gear (something in the 10:1 or 15:1 range).
Lastly, you'd be shocked at how small you can package a simple spur or helical drive train. I used this sucker for a project once: https://www.pololu.com/product/1595/specs
It's 10x12 x 29.5mm WITH THE MOTOR and the gearbox is nearly 1000:1

 

[Oilytrunk]

As you already mentioned, planetary gears are highly versatile. If you go with a more complex design, you can get quite a high reduction in a fairly tiny space.
Cycloidal gearing is another option you should explore.
Rumour has it, contrary to popular belief, that you can achieve fairly decent efficiency with a relatively low reduction worm gear (something in the 10:1 or 15:1 range).
Lastly, you'd be shocked at how small you can package a simple spur or helical drive train. I used this sucker for a project once: https://www.pololu.com/product/1595/specs
It's 10x12 x 29.5mm WITH THE MOTOR and the gearbox is nearly 1000:1

This should do.