ROBOTICS | Measuring repeatability of a strain wave gear from Harmonic Drive

A high gear ratio with no backlash in a very compact size – is what makes the strain wave gear a key component for precision industrial robots. The strain wave transmission (also known as a harmonic drive) was invented in the fifties and has not changed since then. Moreover, it's difficult to find better alternatives to this day. Thanks to the strain wave gears, industrial robots are known to be extremely repeatable. The repeatability of modern industrial robots can reach a few micrometers over thousands of cyclic operations. For comparison, a human red blood cell has a diameter of approximately 5-10 micrometers. As an example, this video shows the repeatability test of a single-axis robot that uses the strain wave gear from @HarmonicDriveLLC. The measured repeatability is less than 1 micrometer (0.001 mm).

Special thanks to @tinymovr for developing a compact high-performance BLDC controller.

• Project idea
• Design
• Programming
• Filming
• Music

by Oleksandr Stepanenko

#robotics #precision #automation

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Created by Oleksandr Stepanenko

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[stevenmcculloch]

The lighting is so good it looks like like a render

[FlashDrive]

It's insane how precise motors can be these days. Great work as usual!

[navid]

Great demonstration. The music is pretty synched!

[williamforbes]

This video is a phenomenal demonstration

[evanbarnes]

I just realized the indicator is reading micrometers rather than thousands of an inch, and my mind was even more fully exploded

[kentvandervelden]

Maximum overshoot vs approach speed could demonstrate stiffness. Doesn't isolate the gear though.

[lordmemester]

i can't stop watching the last 8 seconds of the video

[Scrogan]

Now come at the same location from the opposite direction so we can see the backlash! I imagine these gearboxes can have really low backlash, but seeing is believing.
The other critical thing is how heavy they wear.

[jnn]

Maybe you can expand on how is the motor controlled with a computer/microcontroller...

[valdaszs]

Just load end effector with compression and tension spring and you see all beauty :)

[dashs]

Definitely have to experiment more with harmonic drives. What did you think about cycloidal drives?

[anthonywalker]

With a mechanical efficiency sub 90%, that’s their downfall in becoming the way, as opposed to an option amongst many.

[SusumoKakinotane]

What are the tech specs of the motor? do you have a link?

[i-make-robots]

what's the model number of the strain wave gearbox?

[cry-wrwt]

Jokes on you 'cause that micrometer doesn't go below 0 :D
Jk, love your videos

[capnthepeafarmer]

I can't remember, but are harmonic drives backlash free?

[localhawk]

Gravity might help here a litte bit ;). A confirmation on a vertical position would be interesting.

[leonordin]

If only u did the other direction as well. Going into minus then back, stop at zero and to the start. For backlash measurment.

[gerryakbar]

But how about the gauge's repeatability