Virtual Sphere Rolling Joint Robot Arm (DYNAMIXEL + OpenRB-150)

I have build very unusual Robotic Arm. Its unique design allows for the organic motions, which are not accessible to other robots. Here the link to the controller used (it's super new!!!):
OpenRB-150: bit.ly/3PJdQDZ
Special thanks to my special Patrons: Benjamin Bacon, 천희 한 and Orleans!
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#DIY #Robotics #robotarm

[@Skyentific]

In order to finance my KZbin channel and my projects, I am starting the consultation in robotics. So if you would like to ask me questions about my builds (or about your projects) you can do this through my website ( www.skyentific.com/book-online ). This service is not cheap, because I would like to limit it (with lower prices I would have to do this all day long, and I would not have time for projects/KZbin). And of course, I cannot guarantee that I will be able to help you during this consultation, but I will do my best.

[@Razzreal_plays]

Spoiler : I watched this whole video, that robot does not roll a joint. Much sad, very disappoint.

[@JinKee]

Add fingers in the next update

[@redbugg99]

Exactly it is a stupid idea ... and so unpractical.

[@lightbatmen]

Для увеличения жёсткости стоит добавить продольные рёбра жёсткости.

[@ilkero1067]

Dear Dynamixel, hope you are reading this. I am already a fan of your products, using them for years now. It is great to see you support one of my favorite channels. Would be happier if you support this channel even more!!

[@StefsEngineering]

The inverted movement reminds me of GLADOS. Cool concept, thanks for sharing! Remember, the cake is a lie!

[@ExtantFrodo2]

Impressive without question. I worry though that if you extend it more than a couple of "joints" the motors won't have the strength to keep it from failing to function or operate.

[@bluddywulf6796]

Try printing with a mesh structure infill instead of solid. it will help with rigidity.

[@davenarisotto3674]

That's a very cool robot arm! It looks elegant

[@clydecox2108]

Very cool robot

[@Skyentific]

Thank you a lot!

[@evanrinehart2733]

Thanks

[@tgfcujhb7583]

Now just to make a bigger one and program it to wash the car 🤣👍👍👍

[@shahriarakbari6771]

It's just brilliant

[@danielb.2873]

Very nice design, love it

[@dontolley1738]

Super cool. Thanks for sharing

[@KaroMaker666]

You can enhance the power using 3 hydraulic pistons from the middle on each segment and reduce the backlash.

[@andriylegayev6571]

this is crazy! (in a good way)

[@Димон_Медведев]

It is will be a really cool cobot

[@atomatopia1]

Now what if, instead of bearing joints, you used rolling joints INSIDE THE ROLLING JOINT

[@rjward1775]

I want to put a print head on one arm and a heated bed on the other for a many axis printer.

[@destroyer2203387]

Обожаю твой канал

[@papydoctor]

Great !!!

[@z1z2z3z]

I have a bit of a rolling joint arm myself, Nom'sayin?

[@mickwilson99]

Fabulous!

[@TheArcanis87]

This is such an interesting design for an arm! I think the overall arm cannot really do xyz and wpr on the end effector on this configuration. Especially the final rotation r looks like it would lead to lots of singularities.

[@isbestlizard]

Is there like 3D modelling and simulation software that lets your design and play with things like this without having to build them for real like just to mess around?

[@isbestlizard]

Like kerbal space program but for robots?

[@Simonjose7258]

Very 😎.

[@gabrielmoreno5329]

could be the shoulder of a robot

[@empmachine]

Awesome work! it pleases both my inner artist and engineer (a great duet of form and function; beautiful). Have you seen the vase-mode printing used for wings by Tom Stanton? It lets him use a really ooozy material that's super light (but still strong). Maybe you can just optimize the materials more? (hahaha maybe you could use an AI to optimize it and then you'll end up with a really organic looking robot arm).

[@chrisbee5286]

Soooo cool. Is it possible to get the file of the 3d Model? I am thinking about rebuilding it. THX

[@bpark10001]

The X-coupling is not an exact rotary joint. The center distance between the 2 parts increases as you swing away from alignment. The deviation is little at first, but increases rapidly the more the joint is rotated from in-line. What benefit does X-connected joint (with 4 bearings) have over single-bearing joint? What benefit does 3 arm connection joint have over "conventional" universal joint? Regarding the arm, servos have no business driving rotational joints where the radius of the rotating element is huge relative to the servo's last gear radius (your 1:2 gearing does little to get this ratio down). The stress is just too high & the arm falls into "toy" class, guaranteed to break on first use. There are also close-spaced bearing pairs that are required to carry the entire torque of the arm. This spacing compared to the length of the arm means huge stresses & poor rigidity, just like the servo torsional loads. Why not couple the sections with universal joint (requiring 4 bearings, spaced apart the diameter of the arm, versus 24 bearings closely spaced) & 2 push-pull screw drives? This setup would be much more rigid & strong.

[@milkrebus3071]

Stop, where are you from? Your english is very interesting

[@cooke828]

this was not the kind of rolling joint I was looking for 😅

[@CKPill]

Yeah me either, but was fun vid.

[@darkfrei2]

Why not worm gears?

[@javiser5614]

Holaaa, me gustaría mucho tener estos st Ya pague la membresia, pero no vienen estos archivos

[@andyvonbourske6405]

you built a Rolling Joint Robot but you don't show your robot rolling any joints ?

[@themarsoff]

Здравствуйте, а как это соединение на русском называется? Виртуальный шарнир качения?

[@bozomori2287]

Sunflowers

[@bylolo4964]

👍 x 1000

[@destroyer2203387]

Добавь шоу. Лазер на голову гидре и пусть выжгет название канала на фанере. Сразу попрут лайки и просмотры. Сбритые усы я заметил )

[@michaelzajac5284]

I wish someone would teach me how to build a robot.

[@Rudmin]

The biggest drawback of the “quaternion joint” is that it’s not actually kinematically defined with true rigid bodies. It relies on tiny amounts of joint slop and elastic deformation to act as a joint.

[@notepadgamer]

Watching these videos is definitely a highlight of my day. Always impressive seeing 3D printing used in such a versatile manner

[@abhiwins123]

One of the chief drawback from mechanical point of view is that at specific angle in 3d coordinate, there will be excessive torque needed for delta movement. Similar to knuckle joint strains at 45°

[@pauljs75]

If it were constrained by an extra armature, it seems it could be used as a constant velocity joint. But again it may be limited by torque loading... However I wonder if that could be worked from the other direction by using a CV-joint design that handles torque well as a robotic armature if it's not constrained like it would be on a vehicle drive line?

[@abhiwins123]

@@pauljs75 I liked the counter idea, its an idea worth exploring.

[@keixsy]

could someone explain this but for dummys? (me)

[@gamerfortynine]

@@keixsy The design allows angles with lots of stress against specific joints. I.E. too many hard materials to flex and distribute the stress accross the entire structure.

[@JinKee]

@@pauljs75 look up the Thompson Coupling from Australia.

[@vell0cet517]

I'd love to see how you worked out the inverse kinematics for this thing. That would be a great video on its own. These spherical parallel manipulators are just so mesmerizing to watch. They remind me of a delta 3d printer in some ways. Beauty and engineering. Well done. I think it'd be cool to stick a 360 lidar on the top of one and use it for slam mapping in 3d.

[@missingpartsclub]

It's an interesting concept. Idk if you've seen what naver labs with the ambidex used this joint for, but very similar application. If you decide to expand on this project you might try changing the drive ratio from 2:1 to 4:1. That would increase your avaliable torque but at the cost of speed. Great work as always. Keep it up!

[@Димон_Медведев]

Hello, my favourite cyborg. 😄

[@vip8877]

Я даже не сразу врубился, что видео на английском языке)) Русская речь на английском языке))) мне понравилось, спасибо!

[@jasonrhoades4122]

That has got to be the absolute coolest robot arm I have ever seen!!! Now I want to print my own, lol. Thanks for sharing.

[@redmasterv2.031]

Perfect Russian accent Прикольная самоделка👍

[@skaramicke]

I would love to see this configuration done in aluminium and with greatly increased gear ratios. It feels like it could be 1:100 instead of 1:2, and still have usable top speed.

[@maxgood42]

Then mount it on tracks with a FLIR camera and let it roam around the streets at 3am .

[@ionutdimache3509]

You talk about harmonic drive? ;)

[@CharlesVanNoland]

Just need a higher gear ratio - smaller gears on the motors and larger gears on the joints, to maximize torque on there :D

[@michaelrichey8516]

Your test at 17:00 is the money shot! That's the one I was waiting for - stable platform rotating is sweet! Well done!

[@NathansBarelyUploads]

Women are going to love this

[@kristiansims]

Really cool to look at, though it seems a bit inefficient to use three motors for two degrees of freedom at each stage. I wonder if there’s a way to recover that with a rotating DOF between stages that could come from a sum of all the motors or something with a differential like that.

[@merlinjim]

Yeah he actually missed in his explanation that you can rotate+translate Z by rotating all servos the same direction. So the 3rd DOF is not something a traditional roboticist considers a DOF since its a mix of two DOFs. The 3 motors do all contribute their power to motion so having a 3rd one is not inefficient even if you constrain the calculations to not rotate the platform

[@Skyentific]

Link to the controller (Super New!!!) OpenRB-150: bit.ly/3PJdQDZ

[@glowytheglowbug]

niceeeeeeeeee

[@dc37009]

ARD-BOT-EMB~PO ~~$25-OpenRB-150-Arduino Compatible DYNAMIXEL controller - KZbin ! Very niceeeeeee ! ...Thanks awesome vid !

[@NiCeDarox]

have you tried to replace the gears between the plates with worm gears to make it more stiff? The worm gear can move the upper gear but the upper gear can't move the worm.

[@Derian_De_Grey]

Йоур инглиш из вери гуд😄👍

[@vmened]

Hi, i found new way to build reductor with planetar gear and ratio 354:1. May be it will be interesting for you kzbin.info/www/bejne/o5zdnoWfd62rmbs

[@tariq7772]

Lol, I spent an entire weekend in Fusion 360 recently "inventing" this very same basic joint structure. It goes without saying that there is nothing new under the sun and brighter minds have usually tread the same ground. Keep up the great work and thanks for sharing!!

[@dm5rkt]

Also have a look at Mark Rosheim's Omni Wrist 3 mechanism.

[@tariq7772]

@@dm5rkt Thanks! I just uploaded the concept I worked up. It moves in 3DOF, but would require linear actuation/artificial muscles to control. Not sure how practical. kzbin.info/www/bejne/pYCmYXmuorJnjaM . If you have seen my concept worked out further somewhere, let me know. I am not trying to be original, lol. Just want a compact solution for a "shoulder" joint. Of course my joint suffers from multiple positional limitations.

[@gendragongfly]

There is another benefit to this design, modularity. Your first 2 axis have the same configuration and the same hardware as the second 2 axis and so on.

[@simons3943]

If I become a patreon do I get access to these files? Would love to build one myself!

[@kartikeyawalia]

Hi, I have been following your content and it has been very interesting and informative. Just a suggestion for this design- at every stage you just need 2 actuators instead of 3 as according to my understanding any 2 of the arms are active and the 3rd is kinematically coupled. It will reduce the weight of the stages and might help the robot dynamics.

[@xaytana]

In theory you only need two motors per joint, in practical application you need three for holding strength. There's also reasons why tentacle-like arms do not approach their design like this, but rather use air bladders or wire actuators that have a larger motor in the base, with a more simplistic design that uses a flexible non-compressible spine between the actuation discs; not to mention higher arm rigidity and less complexity in these models. Though the alternate design does require three actuators, or four depending on design, due to actuation not being linked to the spine itself as it is in this model. The older iterations of the LIMS2 AMBIDEX wrist used a similar model to the alternative, having actuation be separated from the spine via wire actuators, though they used a mechanical spine of the same design as the segments shown here; the key point here is that the spine is not directly linked to the actuators. This design realistically works for only one to two segments do to its downfalls, whereas the more optimal design can go for many more segments. I have a feeling, due to the downfalls of this design, that this project would become a sunken cost fallacy even for the best designers, there's just no good way to optimize all the problems, whereas an alternative provides less issues from the start.

[@kartikeyawalia]

@@xaytana I agree with your point. Another design that can be an alternative for a quaternion joint used here is an Omni Wrist by Ross Hime Designs Inc.

[@scottjackson2812]

Really cool! You could add another DOF by putting the base on a rotating axis.

[@GameTL]

Thank you for the effort in explaining the concept in the beginnning.

[@NoahZipin]

Can you provide the paper that you referenced for the kinematics of the rolling joint?

[@Skyentific]

Quanterion joint: Dexterous 3-DOF Joint... Yong-Jae Kim. 2018 IEEE, 2018, 935

[@nou5440]

second reply to the first comment

[@NoahZipin]

@@Skyentific thank you! Really impressive video. Seems like a rigid solution to continuum arm robot! Wondering if vibration can be dampened even more...

[@maeve615]

I wonder how this would hold up as a joint for rotary power transmission.

[@aaronthomas8834]

This is awesome! It’s like a mechanical elephant trunk. It’d be awesome to see 10 of these joined together getting progressively smaller by a factor of 1.618. I’d love to see this in 6061 aluminum with the proper power and servos. This arm would be extremely helpful in space on the ISS or on a moon base. Imagine it on an automated gantry that can move in x y and z. It could put together entire habitats and move parts etc.

[@markusbuchholz3518]

Thank you so much for depicting your wonderful project. Your work and effort are oustanding. Your movies have been providing excitement and inspiration for so many years. Thank you again!

[@redbugg99]

It looks like a great idea but in fact a stupid idea .... IF you need to apply force assuming is made of titanium or some super metal ... the articulation of every joint will twist making it impractical. I think you are fascinated with this witch is great .... so instead of making videos that get 250k views in 2 years make a video of something practical ... Atlas 3 i think is the best design out there and NO, no one spect you to do better. All im saing is to make your own ideas not making someone else popular. And dump that stupid thing.

[@ps6k4trk33]

Very nice project, very interesting for solar's panel purchasing applications, congrats

[@robotflex]

I enjoyed it. It's cool! Please come and see what I made with 2 axes! (with DYNAMIXEL 2xl430)

[@mirceapaulmuresan]

Very cool! Now that you have DYNAMIXEL servos it would be cool to see a comparison between them and the GYEMS motors and maybe other servos as well :)

[@porkrinds9572]

Perhaps the use of worm/screw type gears on the motor side would work better? Also have the added benefit of reduced play in the driven structures to act as a better braking mechanism...?

[@robinchazen159]

I was thinking the same thing, and drive them using cables (like a Dremel flex shaft) so all the motors are in the base. That will also cut down the weight of stage 2 and 3 drastically.

[@The-Man-On-The-Mountain]

YT: "I saw that you are a snowboarding teacher who also like video games and memes, and you don't know sht about robotics, engineering, or the most basic maths operations. Here is this video for you" Me: "Thank you".

[@markTheWoodlands]

This is a fantastic way to teach the concept of adding degrees of freedom incrementally to an initially simpler setup.

[@Lion_McLionhead]

Alt azimuth joints don't have to worry about losing their jobs to sphere rolling joints.

[@Bloomio95]

I would love to see this concept in its full potential! So with higher quality parts for less wobbling and more powerful actuators. Great work! I´m planning a fully mechanical arm with 3-4 joints. Any suggestions on how to control the speed of the gears (the resistance) fully mechanically?

[@juliusfucik4011]

Instantly subscribed. Love this! Maybe you could use high speed DC motors with a very low gearing. Then for positioning you could use other concepts; perhaps include orientation sensors or some other kind of feedback.

[@selotmani1]

لم ثلاث سيرفو؟ حركاتهم متصلة ممكن تركيب سيرفو واحد ووصلهم ميكانيكيا. ثم لم تركيب السيرفو على الئراع وهو ثقيل؟ يكفي وصله بكابل وتثبيته في القاعدة باحكام. الذراع هذا قد يركب على راجار او مرقاب

[@Nobody-Nowhere]

joint rolling robot? finally a robot with an actual purpose

[@hardundware]

Wow. Very nice work 😳💪🤟👌

[@nullvoidcrash9605]

Awesome! What 3D sw that you are using?

[@Skyentific]

This is Fusion360. But I plan to move to OnShape (Fusion360 has a lot of bugs on Mac).

[@AlexanderSauerPlaysWithHeroJr]

... some of the wobble and stress on servo's comes from the print.plastic itself... i noticed the arms/legs bend more than the gears you pointed out... but works really well, good design :-) .. pla might not be best.. .. i still have 1976's heathkit hero.jr robots and some hero.sr,with arm/wrist/hand...they use servos .. have 6v battery supply.. 3,8Ah...but its oldschool heavy metal arm meant to pickup and hold stuff... .. so, using more heavyduty servos so you can just make more rigid parts that are heavier might be better , rather than go smaller and less heavy material. .. .. ps... using puppet making tricks in design , you could use heavyduty servos in the base ..and run double 1:1 cables to the joint(s) servos...then you dont need the little servos installed in the joints ...but move to the base .... by combining the cables , because for many desired position one joint always will move with other... the you could use less servos.. but get to design a 'programable'gear/switch box...lol. i make cosplay ,puppets n marionettes...and thats why i said ,you can move the heavy servos all to the base, even reduce some , depend on what you need it to do. that how marionette fx work...no space in puppet...all fx and control must be run in wire to controller.. look up how techique of marionette fx and builds online... ? might give you clever idea already used for complete opposit reasons... hihi.... hope it helps,

[@dalianiazy5100]

Amazing work, would you kindly tell me the reference paper (for calculations) used? Thanks

[@YuriyKlyuch]

Was there any jokes about “erectile disfunction” in the comments? Seriously though - very impressive, as always!

[@jonernst4413]

Change gear ratio from 2:1 to 3or 4 :1 stiffen up arms with ribstruckture/trusse structure or viagra ;-) Spell check no way 😞

[@justthinkingthoughts]

Just an idea, without undetstanding the geometrical operation in detail ... Couple the three axis with gears and drive two of them and let the third free spinning. Backlash elimination might bite the grass but you could use worm screws for the axis for better torque... Maybe the third axis needs a brake for holding

[@IhabFahmy]

Cool engineering exercise... but what's the advantage of a rolling joint robot over the pin joint used in robots now? In your design, you use three servos for 2 DOF, which seems wasteful.

[@porkrinds9572]

Also looks like this could work as a sort of CV Joint with extended angular working range for delivering rotational force. Would need some serious reinforced alloy arms and tight tolerance bearings though. Absolutely love your videos, sir!

[@carlosmontgomery4178]

I asked the same question.

[@pauljs75]

Ditto on that. CV joints and "virtual sphere rolling joints" solve the same problem, just for different applications. And given the variation in existing CV joints, modifying one of those may suit this purpose in a more robust fashion.

[@secretender3421]

Apply some “fast twitch capabilities” and a stronger, flexible enough skeleton and you got a runner

[@zotkindm]

Любопытная самоделка. Английский у тебя конечно серьезный))))

[@elrinstrongsword]

I love your work and would love to see this with CNC tool steel or titanium construction and capstan drives scaled up to enormous strength

[@qwertyzxaszc6323]

That mechanism would also be great for the spine of a robot, giving it a lot of mobility. Also, I wonder if this mechanism would be better if it is driven by cables rather than gears.

[@Devo491]

The upright demonstration (@ 13:00) looks so much like a struggling erection, it made me laugh! Great project, suggest hydraulic (or air) actuators to make this a useful machine.

[@jaimetomasicart3129]

Hi, greatings from Argentina. I have a very stupid question. If with 3 links per section you have not as rigidness as you what. Why dont you design a 4 link section? You will have more weight but another servo in it to fight that. I also asume that you already think this. If you did what didnt work out?

[@pand0ras]

How you google that mechanism? "Rolling Joint" gives you all the 420 content instead of engineering.

[@icebluscorpion]

Under the table, it looked like an elephant foot. If it was more powerful and sturdy enough then you could build a hypermobile Mechanic cyberpunk elephant XD

[@maxim9875]

Hey! Would you be Willing / able to create a exoskeleton for a shoulder/arm (i have a reverse prostetic shoulder at age 30 and this is limiting my capabilities)

[@ArnaudMEURET]

Why not just take Koreatech’s design instead of reinventing square wheels?

[@aalaal171]

Hi sir, amazing work! Can you please make the next video of strength test to see how and how much weight it can lift and move it around? TQ

[@JinKee]

Dynamixel? When you said "cheap" I thought you were going to get no-name aliexpress servos

[@Advatar042]

you know if i could be speeded up and then the top spin. that could be a Great Thrill Ride and like Six Flags Great America or any adventure park.

[@buck-johnson]

If you put this together with the Nvidia Orin facial recognizer and a lazar gun you could help the Cylons win.

[@jpsousa4]

I watched a video about rolling joints and didn't even learn how to roll a single one. Kidding, this is a really cool mechanism. Thanks for putting this video together! :D