ROBOTICS | Backdrivability and speed test of Harmonic Drive-based robotic actuator
Vložit
- čas přidán 4. 09. 2021
- This video briefly demonstrates a high-speed positioning test of the robotic actuator based on the strain wave gear from Harmonic Drive. The average input speed recommended by the manufacturer for this particular gearhead is limited to 3500 rpm, which accordingly gives 70 rpm (or 420 deg/s) on the output flange of the gearhead with a gear ratio of 50:1. In addition, the test shows that the actuator can be easily backdrivable, which opens up many opportunities for human-robot collaboration.
Instagram: / olekstepanenko
• Project idea
• Design
• Programming
• Filming
• Music
by Oleksandr Stepanenko
#robotics #engineering #automation
In order to repost this video, you must add the following in your description (including the links below):
Created by Oleksandr Stepanenko
CZcams: / oleksandrstepanenko
LinkedIn: / olekstepanenko
Instagram: / olekstepanenko
Any modification of the video or audio in any way is not permitted. - Věda a technologie
The speed and accuracy of harmonic drives is incredible to me
I wonder if those actuators can be miniaturized so that they'd fit in a prosthetic hand. Imagine a myoelectric hand that has that level of responsiveness.
Yes, definitely! Check these publications: www.researchgate.net/publication/233703891_Investigation_and_strategies_for_precision_of_miniaturized_robots_with_micro_gears
and
www.researchgate.net/figure/Micro-Harmonic-Drive-gear-train-made-by-Micromotion-GmbH-Mainz-Germany_fig5_225550342
A distribution of Facebook reality labs is working on prosthetics I don't have a link sorry as much as I dislike Facebook they are pushing this technology further than it's ever gone I wish you luck and hope this industry grows even more
Clinically underrated
I feel like this is going to be expanded upon.
Then I'll try to justify your feelings 😉
we use harmonic drives in low torque applications. SCARA robots, laser axes, once we get to larger robotic systems we switch to planetary systems. The little harmonic wave generator isn't good in those high torque applications, they tend to slip and damage the wave gear. Though for small robotics they work great!
I'm building a scara bot arm as a hobby project at the moment, my initial design uses planetary gearboxes to get the most out of the small 200W ac servos chosen. I have been looking at harmonic drives recently because of the much better backlash. At J1 the gross mass is around 16kg. Would you recommend sticking with planetary in this case or going with a fairly large harmonic drive (looking at 60Nm average peak load for the speeds I'm aiming for)?
Thank you for this information. I'm a robotics hobbyist and the professional experience is appreciated.
I would like clarification on one point: when you say that small harmonic drives tend to slip and get damaged in high-torque applications, does this not assume that the harmonic drive is non-backdrivable (or perhaps is backdrivable but can't handle shock)? I thought professional-grade harmonic drives were common in stationary robotic arms used in assembly lines that cannot be backdriven, and thus enjoy high accuracy at high speeds, plus the motor controller can (mostly) be pre-programmed for specific paths. The torque-damage threshold of a small harmonic drive can be increased by combining it with a planetary gear setup. Extreme-torque applications should have a separate braking system that automatically engages if the robot loses power.
Comparing pictures of industrial 6-axis/7-axis robot arms lifting welding guns vs. lifting cars: the motors look identical but are different sizes and are connected to different gear setups, and braking mechanisms look different and may or may not be present (I acknowledge I'm a layperson and pictures can be deceiving).
Cycloidal drives are preferable for mobile robots, where the backdrivability allows the motor controls to compensate for unpredictable torque requirements caused by uneven terrain.
This video shows what appears to be a reliably backdrivable harmonic drive with 50:1 gear reduction. If performance and cost are competitive against cycloidal drives, this harmonic drive may be viable for mobile robots, or for assembly line applications on SCARA or 6-axis/7-axis robot arms that feel mild shock.
Presumption: if a mobile robot jumps from a high ledge, the torque will be severe upon landing. This 50:1 backdrivable harmonic actuator will transfer this burden to the motor in a fraction of a second, during which time the strain-wave gear teeth will experience severe stress. Cycloidal drive trains are inherently good at handling this shock, harmonic drives are not.
Having said that, the robotics on Mr. Stepanenko's channel are exceptional quality, so I'm inclined to think this harmonic actuator may be useful under certain conditions.
Seems Like Magic :)
I hope we get to know some insight of what controller and programs your using !
@@shashankshekhar6549 Thank you! Sure, here is the controller: tinymovr.com/
@@OleksandrStepanenko ooh!! those are really good. Performance at an affordable price.
you need a global shutter sensor camera to catch up with your motors mate
Yes!
Well noticed!
@@OleksandrStepanenko Robotics & Image Processing my main hobbies :)
This is absolutely stunning! Do you have any info on the gear module used? Or is it not on the market?
Thanks! www.harmonicdrive.net/
Good work, keep us posted!!
Thank you!
This is astonishing, do you mind me asking how much did this strain wave gearbox cost?
Thank you, Ali. It's quite expensive indeed. I think it would not be ethical to discuss the cost... Try to request Harmonic Drive directly, I'm sure, they will answer.
Interesting actuator! Where can one source one of these?
Thanks! I don't sell it at the moment, but you can check out the actuators from Harmonic Drive: www.harmonicdrive.net/products/rotary-actuators
Speeeeeeeed
Great Videos Oleksandr ! the beats are rock! Did you composite the music as well? If yes, witch software did you use?
Thank you, appreciate your comment! Yes, I use Logic Pro. You can also try GarageBand, it's free and pretty good as well.
Beautiful
Thank you!
Nice example! Can you share some data about the actuator? What is it's torque? And does it have any particular precision?
Thanks! At the moment I have only tested the precision: czcams.com/video/r5FCMSFGZQs/video.html
Love the sound
Thank you!
Dr. Oleksandr and colleagues, please excuse my illiteracy in the field. I am trying to learn. What are the challenges in the presented mechanism in the videos? Would not a simple stepper motor do the same?
Hanzhen harmonic drive gear , strain wave redcuer,
robot gear joint , over 30 years experience
So how is it possible to back-drive a harmonic drive?
yes
Very cool what does the side view look like ? Can you run at high frequency ?
Thank you! I will show it in the next videos.
Wait how the hell do you backdrive a harmonic gearbox?
With a 50:1 ratio no less!
Harmonics below a certain ratio are backdriveable. A force applied to the output will cause the flexspline to deform in a way that exerts a rotation on the wave generator.
It's mechanically backdrivable with the motor off.
Otherwise, many Industrial robots would break into pieces if there were a power outage.
The strain wave is backdriveable, and the power-off brake needs to have a dynamic braking specification.
Just as described in Spaceballs: we have to a low down first.
m.czcams.com/video/ygE01sOhzz0/video.html
What the cost of a motor like this at per piece vs bulk buy of 20+?
About 100 euros per motor (check maxon online shop)
Can you give the link of the bldc flat motor that you used?
What is the Morter Model number? I wanna use them in my project for school
Great
Thanks!
Reminds me of my washing machine
Hello Mr. Oleksandr,
Can you please give the link (to buy) for the motors you showed in the previous videos?
Sure, www.omc-stepperonline.com/nema-11-bipolar-1-8deg-12ncm-17oz-in-0-67a-6-2v-28x28x51mm-4-wires.html
Hello is it the motor you used in this video? I thought it was bldc
Would you please tell us what kind of motor and driver you are using here?
Sure tinymovr.com
Is it a bldc motor in the back? If so, which controller is it?
tinymovr.com
Is there any good online site so that to buy robotic things?
tinymovr.com
Where's that bottom plate from? Where can I buy 3?
www.thorlabs.com
*Dang.*
attach some metal ball to hit micrometer :)
Sure, this is in my plans 😎
What motor did you use for this? :)
bldc flat motor
What is the model you used? Can you give the link?
yes please 🙏
Is super smooth slow movement possible?
Yes, definitely!
Noisy. Does it have torque sensing capability?
So basically you can read/record your driving it?
I mean like, instead of controller -> robot, go robot > controller and read the values etc
@@eurybaric Exactly. I can teach a position by simply moving it manually.
@@OleksandrStepanenko That's amazing! I'm not in the field in any way, but i'm imagining you would teach it a sequence, then clean it it up in software, yeah? And follow up, what's the resolution on something like that (distance and time)? In any case, awesome stuff :)
From where we get this driver ?
tinymovr.com
what is the model name and from where can I buy it
I don't sell it at the moment, but you can check out the actuators from Harmonic Drive: www.harmonicdrive.net/products/rotary-actuators
More like slow loud test
Audio was very echoey, kind of takes away from the staged feeling.
I agree, audio is not the best here...
gwcfj
vur.fyi
Harmonic drives are 100% not back drivable
No way 😮