DIY Actuator for quadruped robot based on a ballscrew: Powerful!

We build and test a powerful robotic actuator based on a ballscrew, a brushless motor, an ODrive board and a magnetic encoder

[@LautaroOrdenes]

"Fabulous video, it's great to know that there's someone opening up this knowledge to the public."

[@rodstartube]

partially, no info about odrive settings

[@HOXrobotics]

If you find this useful, I will do it in the next video

[@Zestybwoi]

Who are you quoting?

[@freakinccdevilleiv380]

Excellent. You should have a lot more views.

[@whitneydesignlabs8738]

Super cool. Do you intend to post any plans, drawings, or parts lists? This would be fun to recreate. It seems like this actuator could be strong and fast. Also the design seems like could be adapted to bipedal robots as legs or arms. Seems like it would be fast enough to handle balancing operations.

[@HOXrobotics]

That is the idea, next video will show a 3DOF leg for a quadruped based on this actuator. If you are interested yo can contact at [e-mail]

[@DresdenFPV]

it looks well thought through too! Like having holes in printed parts to assemble through. Nice work!

[@moses5407]

Really great! Approximate cost of parts?

[@critical_always]

Back-seat driver here. Looks like a great design. The only thing causing me to raise my eyebrows was the thin plate motor mount.

[@amoghjain]

amazing job! thank youuuu for such a detailed explanation! learned a lot of new things 🙂

[@BadPractices]

Absolutely beautiful.

[@glasslinger]

The spring in the test fouls the accuracy of the measurement. The arm must LIFT the weights!

[@HOXrobotics]

In the 10 and 15 Kg tests, the actuator actually lifts the weights (you can see the string sliding near the pulley at the endo of the pull). However, it was diffficult to arrange a 20 Kg weight so I removed the weights and just measured the elongation of the spring (previously calibrated with weights)

[@Unmannedair]

It's a clean design. not how I would have designed it, but I'm curious to see how it works out. I suspect that you're going to have some difficulties when it comes to tuning the balancing over uneven terrain.

[@mikelCold]

What would you have done different? And why would you say "not how I would have" without explaining?

[@abhinavt789]

Very nicely explained. Thank you for this video. I would like to learn more about this design. Is there a technical term for this actuator design? What terms can I use to search on Google? Thanks in advance!

[@mikegLXIVMM]

It looks well designed and robust. Thanks for posting!

[@SuperHaptics]

Awesome i like it. But the use of slotted screws should earn you some jail time 😂.

[@jimj2683]

This must be perfect for a humanoid robot!

[@alttabby3633]

Great video! Are you going to share the 3d print files?

[@dinoscheidt]

Crazy that it is back drivable…. Impressive

[@dekutree64]

Assuming that motor is similar to the one I tried, you can replace the bottom 8x22mm bearing with 10x22mm and stick the machined end of the ballscrew up into the motor so it's turned directly instead of needing all that coupler business.

[@HOXrobotics]

What motor did you use?

[@dekutree64]

@@HOXrobotics Surpass Hobby C6354

[@jorgennorberg7113]

You use a 1 700W motor for each joint?

[@PlanB-3751]

That's a genius work😳👍💯

[@davef21370]

Solid and straight forward, good stuff. What's the cost per leg if you don't mind me asking?

[@HOXrobotics]

More or less 150-200 Euros per actuator

[@H34...]

Maybe I'm missing something, but the way you used that axial bearing confuses me. At best it only takes up load in one direction, in the other the motor bearings take all the load. But I can't see what the axial bearing is transferring the load to even in it's working direction if that aluminium bearing block is not fixed to the tube rigidly. Other notes, steel ball bearings on aluminium tube will wear and marr up the aluminium quite quickly, especially since the ball bearing can't actually roll against both at the same time, it will slip against one of them.There are off the shelf POM coated rollers that play nice with aluminium though.

[@HOXrobotics]

Yes you are right, the axial bearing only takes up load in one direction. If this actuator is used in the knee of a quadruped that is enough since the knee will only exert forces in one direction (leg extension). Note that the aluminum bearing block is fixed with four long bolts to a circular aluminum plate that also holds the motor. That bolts take all the load (tension). Sorry but I dont understand your comment on the steel ball bearings

[@hidrogenodeuterio]

El O driver siempre fue tan caro?

[@tadashi_hamada]

The actuator seems pretty noisy. Is it coming from the ball screw?

[@HOXrobotics]

That motor is faulty and something is loose inside and makes that noise. I have replaced it with a faster and more powerful motor and it is now quite silent.

[@justinchang6763]

Beautiful

[@makerslife]

Maybe extend the knee joint through the back and add a gas piston to give some assist.

[@seagsmtrashseagsmtrash1906]

Good luck amigo!

[@rodrigoruiz4345]

Nice!! which brushless motor are you using?

[@HOXrobotics]

In the video you can see a Alien Power systems 6355 60kV, 1700W. Now I have replaced it with a faster and more powerful 6374, 170KV.

[@Suhaib.3d]

Thanks

[@federico6b]

Se nota que eres español! Jajajaja gran actuador, tienes alguna forma de contactar contigo? Gracias

[@HOXrobotics]

jajaja sí, [e-mail]

[@erikkalmar4965]

If u need to do a more powerfull actuator than this u can also use a gearbox. Nice video keep up!

[@DresdenFPV]

or simply adjust the screw to something finer threaded

[@erikkalmar4965]

@@DresdenFPV Not a bad idea, but finer threaded screw can slip more easyly, in the same diameter, because the screw profile is more thiner. It is good for pecision stuffs but if you need torque i gues thicker screw profile is key. I know gearboxes are a bit difficult to make, but if you use gearbox you only need to change motor speed and you get a fast and strong actuator. These days all 3 phase motor is expensive, but u can cheat a bit on price if u go for rpm instead of torque, if i remember it right.

[@HOXrobotics]

The torque is enough for a quadruped, but it needs to be faster. For that reason I have replaced the motor with one three times faster (170KV) and more powerful and the actuator is now very fast (with similar torque). Check my next video to be uploaded soon!

[@Adventures_EC]

you use sketchup? but show solidworks as well? I am confused!

[@HOXrobotics]

I use SolidWorksfor laser cut parts, but also sketchup for fast and easy 3D print design... I should unify this :)

[@Adventures_EC]

yes, especially because Sketchup is made for architects and so I highly advise to switch from it. But it is as you want and feel comfortable @@HOXrobotics

[@rahmanotaibi9319]

Did you calculate the torque? if yes, how?

[@HOXrobotics]

At the end of the video you can see how I calculated the torque: The leg pulls a spring and I measured the its elongation. The spring was calibrated previouslu hanging weights to it . I also used counterweights attached to the leg.

[@ulforcemegamon3094]

While it could make the leg chunkier , there is a fully 3D printed actuator made by Rbotics labs that weights 1kg ,has a maximum torque of 44nm and a continuous torque of 28nm , you could put that actuator to either move the leg or put it as a replacement of the 6 NM brushless motor that you used

[@HOXrobotics]

That is very interesting, however my intention when designing the actuator was to avoid 3D printed parts for gears and structural parts. Thanks!

[@Ajay-di3zn]

Why didn't you use stepper motors?

[@IronReign]

steppers are rarely a good choice for mobile robots. they consume power pretty much all the time. and for a compliant mechanism you'd need an encoder anyway.

[@HOXrobotics]

I agree with @IronReign. Also, there are lots of very powerful and relatively cheap RC plane, drone and skateboard brushless motors that are a very good choice.

[@pachanoid]

excellent!😀

[@RYU47376]

i think the biggest hurdle for this is its slow and doesn't have a natural springiness to it. but great job nonetheless

[@HOXrobotics]

I have replaced the motor with one three times more fast (170KV) and more power and it is now very fast (with similar torque). Check my next video to be uploaded soon!

[@engm5737]

Cool

[@karelmarkvart1517]

All those quadruple robots have wrong construction of rear legs missing important joint - knee.

[@scitator]

very cool! to be continued?

[@HOXrobotics]

Thanks! Yes, I plan to make a 3-DOF leg based on this actuator, then a complete quadruped

[@AESETC]

What is your SOLIDWORKS subscription? What works for you best?

[@microwave-vh2uc]

Tienes al acento espanol

[@ChandrashekarCN]

💖💖💖💖

[@Hukkinen]

Thanks for a pleasant and interesting video 🙂 1. Normalize the audio. 2. Perhaps some of the most obvious pointing of e.g. sliders or cables from A to B is a bit superfluous i.e. video could be trimmed a bit. Subscribed! 😊

[@HOXrobotics]

Thanks for the tips, I´m new doing this!

[@scootergem]

Audio is weak, can barely hear

[@did3d523]

too slow

[@HOXrobotics]

You are right, it needs to be faster. For that reason I have replaced the motor with one three times faster (170KV) and more powerful and the actuator is now very fast (with similar torque). Check my next video to be uploaded soon!