/robowaifu/ - Actuators For Waifu Movement Part 2 Waifu Boogaloo

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Actuators For Waifu Movement Part 2 Waifu Boogaloo Kiwi 09/02/2021 (Thu) 05:30:48 No.12810

(Original thread >>406) Kiwi back from the dead with a thread for the discussion of actuators that move your waifu! Part Two! Let's start with a quick refresher! 1. DC motors, these use a rotating magnetic field created through commutation to rotate a rotor! They're one of the cheapest options and are 30 to 70 percent efficient usually. The bigger they are, the more efficient they tend to be. 2. Brushless motors, these use a controller to induce a rotating magnetic field by turning electromagnets on and off in a sequence. They trend 60 to 95 percent efficiency 3. AC motors, Though there are many different type, they function similarly to brushless motors, they simply rely on the AC electricity to turn their electromagnets on and off to generate their field. Anywhere from 15 to 95 percent efficiency. 4. Stepper motors, brushless motors with ferrous teeth to focus magnetic flux. This allows for incredible control at the cost of greater mass and lower torque at higher speeds. Usually 50 to 80 percent efficient but, this depends on control algorithm/speed/and quality of the stepper. 5. Coiled Nylon Actuators! These things have an efficiency rating so low it's best to just say they aren't efficient. What they are though is dirt cheap and easy as heck to make! Don't even think about them, I did and it was awful. 6. Hydraulics! These rely on the distribution of pressure in a working liquid to move things like pistons. Though popular in large scale industry, their ability to be used in waifu's has yet to be proven. (Boston Dynamics Atlas runs on hydraulics but, it's a power guzzler and heavy) 7. Pneumatics, hydraulics lighter sister! This time the fluid is air! This has the advantage in weight. They aren't capable of the same power loads hydraulics are but, who wants their waifu to bench press a car? 8. Wax motors, hydraulic systems where the working fluid is expanding melted parafin wax! Cheap, low power, efficient, and produce incredible torque! Too bad they're slow and hard to control. 9. Explosion! Yes, you can move things through explosions! Gas engines work through explosions! Artificial muscles can be made by exploding a hydrogen and oxygen mixture in a piston, then using hydrolysis to turn the water back into hydrogen and oxygen. None of this is efficient or practical but, it's vital we keep our minds open. Though there are more actuators, most are derivatives or use these examples to work. Things like pulleys need an actuator to move them. Now, let's share, learn, and get our waifu moving! >--- < add'l, related links from Anon: >Soft muscles with origami-inspired skeletons: https://youtu.be/OJO4FP0DXgQ >Cavatappi artificial muscles: https://youtu.be/yXAJGH5s4cs https://youtu.be/MpCFumHFZvU https://www.designnews.com/automation/cavatappi-robot-muscles-have-5-times-strength-human-muscles >Nameless nanofiber muscle, probably Cavatappi: https://youtu.be/H19p43NFqp4 >Supercoiled polymer (SPC) muscles: https://youtu.be/QHiTJ_zgGME https://youtu.be/N4VMoYFrusg https://youtu.be/hFuzQ4ed-t0 https://youtu.be/2GXWIozM4oQ (bundled/braided) >TCP (the same?) https://youtu.be/S4-3_DnKE9E https://youtu.be/wltLEzQnznM >Twisted string actuators (TSA) <I had the idea that they should in some cases be build with a loop. Grippers would hold a part of it and twist that. For fast release they coul let it go and grab the next part of the loop. Designing the gripper will be a bit of a challenge, though. But I think this is doable. Can't image I'm the first having that idea. <Not sure if this here >>12589 is already something like it bc I didn't understand it. <Here's some passive returning mechanism, followed by other videos on TSAs: https://youtu.be/J26y1nn7JMM https://youtu.be/QBQMZsSQJQM (freaking loud) Effect of bending: https://youtu.be/zYrHGMiqC9A Life cycle test setup: https://youtu.be/PABVsuV7Y1M Frequency response ( I don't get it): https://youtu.be/YLWsh1P80Dc Mixed with fluid/gel tube: https://youtu.be/tP9B3aqc4CI Transmission ratio and speed switch: https://youtu.be/Y1uceDzhjKY https://youtu.be/5PtXTI1t3Po <I don't like it being used for fingers but it's a good technology. >Nylon fishing line muscles: https://youtu.be/Za0VeU9Ov7A https://youtu.be/2OuRX65xbKE <(Reminder: The do have a high life span >1M) <I plan to rather use water for heating and cooling. >Continuous ransmission (CVT) / torque converters https://youtu.be/kVPjhmTThPo https://youtu.be/cd2-vsTzd9E https://youtu.be/c9e2y-5DMNc https://youtu.be/PEq5_b4LWNY >Twisted string series elastic actuator (TsSEA) <This strikes me as particular interesting. https://youtu.be/VBXykAIBKtA >Printed pneumatics https://youtu.be/_X0rDW6NQ58 >Using sugar as soluble support material for printing silicone muscles: https://youtu.be/L0Z0-y3qpNk >=== -add add'l links

Edited last time by Chobitsu on 09/06/2021 (Mon) 10:07:57.

Robowaifu Technician 10/18/2021 (Mon) 01:31:45 No.13671

Nylon actuators seem like a real bad idea also because you'll stress the thread way too much. I don't see why you would choose this method over a simple spool (which has been proven to be reliable and efficient since they use it on cranes) or pair of spools. >who wants their waifu to bench press a car? Patricians.

Kiwi 10/18/2021 (Mon) 03:26:00 No.13674

>>13671 Nylon is dumb as heck for an actuator in a batery and thermal constrained robot. >>13506 ...Why put your rooster near any mechanical joints? Just use an onahole integrated into her pelvis.

Robowaifu Technician 10/18/2021 (Mon) 12:16:22 No.13678

>>13671 >Nylon ... stress the thread way too much Which thread? I think I recall these actuators to be very reliable. The developers tested them a lot and made this claim, if I recall it correctly. >over a simple spool Because the spool implies a motor, and it might be slower and certainly louder. You could have both. The Nylon is only used if the weight is to high for the other ones. >>13674 >Nylon is dumb as heck for an actuator in a batery and thermal constrained robot We had this several times here on the site. You're thinking in terms of the option of heating the Nylon with electricity. But hot water can be used, which might already be there anyways. It depends on the design of the robot. Like it or not, some might use that approach. Even the method with electric heating might be interesting for some smaller movements, e.g. in the face. Though, dielectric elastomers might be better suited in that case. Nylon actuators are also quite slow, so it's for some special use cases, especially support for other actuators in case of heavy lifting, but not generally useless. Don't judge everything based on your approach.

Robowaifu Technician 10/18/2021 (Mon) 23:00:33 No.13687

>>13678 Okay I totally misunderstood the way these things work. From the OP picture it looks like they are motor-based like a simple spool, but the motor is perpendicular and contraction is provided by overtwisting. I am now aware that that is not the case and I'll concede that they actually are cool and potentially useful.

Robowaifu Technician 10/19/2021 (Tue) 00:37:20 No.13688

>>13687 What you thought of is a twisted string actuator. I just got my drone motors and want to try those out for that.

Robowaifu Technician 10/19/2021 (Tue) 01:21:04 No.13689

>>13678 >heating nylon as a wire and totally not causing a house fire. >Hot water? From where? The cooling system? How would it help movement?

Robowaifu Technician 10/19/2021 (Tue) 02:44:02 No.13690

>>13688 Good, that's a genuinely good actuator mechanism and I hope you share your findings. Just know that drone motors require cooling if they are used for more then a few seconds at a time.

Robowaifu Technician 10/19/2021 (Tue) 18:05:00 No.13701

>>13689 Please read through the existing information before making some bold posting. There are actuators with thin wires and Nylon. Also, yes, hot water comes from the cooling but could also be heated on purpose if necessary while being plugged in. Actuators help movements by actuating or so, I think.

Robowaifu Technician 10/20/2021 (Wed) 17:33:47 No.13723

Has anyone replicated some bldc-actuated limb projects on hackaday? https://hackaday.io/project/181799-redacted-the-first-fully-open-bipedal-robo There are several great open-source projects which are a good place to start to actually build a robot instead of theorizing about what would be the perfect actuator and never getting anywhere. I was on a tear with nitinol braided actuators being the perfect actuator, but the part manufacturing held me back to the point where all I could work with wasn't nearly good enough. We need to start with something at all in order to have a hands-on perspective of what works and why to build these robots at all. Even a perfect first design nearly always has something go wrong with it, which is why iterating versions is a superior method to getting stuck in theoryland and never making anything.

meta ronin 10/20/2021 (Wed) 19:34:58 No.13724

found this just now https://www.youtube.com/watch?v=guDIwspRGJ8 >We have achieved strong, fast, power-dense, high-efficiency, biomimetic, soft, safe, clean, organic and affordable robotic technology. Dumbbell weights 7 kg (15,6 lbs) , forearm with hand only 1 kg (2,2 lbs). >This artificial muscles robotic arm is operated by water and consumes 200W at peak. We invent and produce our electro-hydraulic mini valves to have complete controllability of speed contraction and compress the whole powering system (for a full body) inside humanlike robot torso. >At this moment our robotic arm is operated only by a half of artificial muscles when compared to a human body. Strongest finger-bending muscle still missing. Fingers are going to move from left to right but they don't have muscles yet. Metacarpal and left-to-right wrist movement are also blocked. This version has a position sensor in each joint but they are yet to be software-implemented. We are going to add everything mentioned above in the next prototype. >The movement sequence was written and sent by simple commands to a hand.

Kiwi 10/20/2021 (Wed) 19:42:10 No.13725

>>13723 To my knowledge, no one has replicated a Hackaday project here. That project is ok as a concept but, is severely flawed. All of the mass is centralized high up in the hips which means it would lack any stability IRL. It also suffers from having brushless motors close enough for the magnetic fields to adversely affect each other. The flaws in the design continue but, this is not the thread to discuss why that design would not make sense IRL. As for this thread, it was made for the express purpose of discussing actually useful actuators. Anon's enjoy dreaming about super coiled actuators and other ultra low cost actuators that do not actually make sense to use for various reasons. My guess is they want their waifus to be cheap to produce. I will continue to tell everyone to use DC and brushless motors as they are the only sensible option currently available unless she's constantly plugged in. Steppers could also work and are very cheap for their strength, they're just heavy.

Robowaifu Technician 10/20/2021 (Wed) 20:03:36 No.13728

>>13724 That thread mentions him in the "Humanoid Robot Project Videos" thread: Automaton dev from Poland >>5136 >>10179 >>13304, but I don't post every video of his. Crosslink in the actuator thread also exists.

Kiwi 10/20/2021 (Wed) 20:07:40 No.13729

>>13724 If only we had power systems capable of delivering hundreds of watts over prolonged periods. If only water was not heavy. These actuators are such heart breakers. They seem almost fantastical until you realize how inefficient electrolysis is for a pneumatic system. There's also the major problem of making sure the hydrogen and oxygen do not escape the system and reconstitute into water at the right time. This Eastern European man explains how the system actually works. https://www.youtube.com/watch?v=gy-Cl8X6Itk

Robowaifu Technician 10/20/2021 (Wed) 20:53:05 No.13735

>>13725 >thread, it was made for the express purpose of discussing actually useful actua It's the official thread for actuators, so we'll discuss all of them here. Being strongly opinionated doesn't mean you're right. >continue to tell everyone to use DC and brushless motors as they are the only sensible option For her primary joint movements it might be the best approach, but can still be combined with other accuators in case of lifting something for example. >unless she's constantly plugged in She can be plugged in most of the time, while not moving from one place to another. While sitting she can be plugged in. Then doing some movements while laid down or standing somewhere won't need much energy.

Robowaifu Technician 10/20/2021 (Wed) 21:38:51 No.13738

>>13723 >the-first-fully-open-bipedal-robot I answered here, in the meta thread: >>13737

Kiwi 10/20/2021 (Wed) 23:37:23 No.13750

>>13735 Hm, it would my personal biases have poisoned my judgment. I forgot there were those among us that would want a plug in waifu. I only want a waifu that can follow me so I only think about robowaifus through the lens of one that must be self powered.

Grommet 10/21/2021 (Thu) 01:31:37 No.13755

>>13724 That's very impressive. Having hydrogen and oxygen in the same tube is...risky if I understand it correctly. Maybe he has a way to separate them. Not sure. He is making a gas to drive pneumatic actuators which is a good idea. It happened to occur to me possibly a spark gap which can expand water, or other liquid, would work as well??? Not sure it may be even more inefficient than splitting water. Maybe you could use some other sort of element that spit into a gas although I can't thing of one off hand. I'm complaining about the shortcomings but don't think I'm not impressed mightily by what he has done. It's very excellent.

meta ronin 10/21/2021 (Thu) 08:43:51 No.13760

>>13755 >>13729 >the major problem of making sure the hydrogen and oxygen do not escape the system ... >Having hydrogen and oxygen in the same tube .. H and o2 aren't going to be at standard pressure, that's something to factor in. No need to worry so much about escape, since that's still an issue in pneumatic and hydraulic systems regardless (and more dangerous in the latter). What's really interesting here is the way the actuators are arranged like muscles - with apparently opposing muscle pairs for greater control rather than jerky one-way movements or rigid machinelike movements. However don't rule servos out entirely they, and solenoids as well can do a lot still. Consider the human body, it has smooth muscle, skeletal muscle (slow and fast twitch) and cardiac muscle. Similarly, we should expect to use a diversity of tactics to the actuator problem. 1 .Hydraulics or large pneumatics where the most power is needed (shoulders, bicep, legs), 2. Where some power but more control is needed: wrists, neck, feet/ankles: smaller pneumatics (they don't have to be micro, but an array of micro pneumatics shouldn't be ruled out), the hydraulic transformer that other anon had mentioned, and/or pulleys which sound low-tech but don't have to be: try to envision something like a metallic herringbone chain inside a lubricated graphene or nylon weave bladder. 3. Finally for fine dexterity: nitrile wire or something similar from the "soft robotics" school: fingertips, facial muscles (when we cross that bridge), etc. Anyway I wanted to respond to you both before sharing this too: https://www.youtube.com/watch?v=6JNq1COqB_s[Embed] https://spectrum.ieee.org/kenshiro-robot-gets-new-muscles-and-bones

Robowaifu Technician 10/21/2021 (Thu) 14:07:18 No.13761

>>13506 >...to put your fingers and other fleshy bits near? Redundant sensors are your friend. Also, having the system only use so much force as necessary for each movement. Also, there are the terms 'compliant' and 'backdriveable'

waifusearch>  backdriveable OR backdrivable

   THREAD SUBJECT                      POST LINK
The Basement Lounge                >>4807    backdriveable
Robotics Hardware General          >>12511     " 
Actuators for waifu movement!      >>7086    backdrivable
   "                               >>8207      " 
   "                               >>9198    backdriveable
   "                               >>11700     " 
   "                               >>11855   backdrivable
   "                               >>11881   backdriveable
Work on my Elfdroid Sophie         >>7675      " 
   "                               >>7693    backdrivable
   "                               >>7695      " 
   "                               >>7701      " 
Actuators For Waifu Movement Par   >>13761   backdriveable, backdrivable

' backdriveable | backdrivable '  =  13 results

waifusearch>  compliant OR compliance

   THREAD SUBJECT                      POST LINK
C++ General                        >>1073    compliant
Robotics Hardware General          >>12511     " 
R&D General                        >>2048      " 
Wifu that gives you Hope.          >>6823    compliance
   "                               >>6827      " 
General Robotics/A.I. news and c   >>6229      " 
   "                               >>6231      " 
   "                               >>6381    compliant
   "                               >>6919      " 
   "                               >>12586     " 
Actuators for waifu movement!      >>8207      " 
   "                               >>8221    compliance
   "                               >>11023     " 
   "                               >>11028     " 
   "                               >>11030   compliant, compliance
Prototypes and failures            >>12882   compliance
Why consider alternative CPU arc   >>4506    compliant, compliance
Robowaifu Power and Control Syst   >>11175   compliant
Actuators For Waifu Movement Par   >>13761   compliant, compliance
Madoka.mi prototype thread & rob   >>13511   compliant

' compliant | compliance '  =  20 results

Cycloidal drives with a gear ratio of maximum 10:1 are backdriveable, along James Bruton. A soft outer shell might also help with your concerns. Doing such a search with waifusearch requires the option "-y false" when starting the program from the shell. >=== -I hope you don't mind Anon, but I cleaned up your waifusearches a bit. I suggest you post them on the board inside codeblocks, as I've done here for you. This will help ensure the browser rendering of contiguous spaces is monospaced. -Also, I'd suggest you upgrade your Waifusearch copy to the latest v0.2a (>>8678). As you can see here, among other improvements, basic Boolean OR is available for different (though related) search terms. -Also, there's a newer version of the all_jsons just posted; 211117 - https://files.catbox.moe/jgmdxs.7z Cheers. >t.Chobitsu -edit waifusearch results

Edited last time by Chobitsu on 11/17/2021 (Wed) 11:09:26.

Robowaifu Technician 10/21/2021 (Thu) 14:13:52 No.13762

>>13754 Yeah, I knew the links weren't working. But for some reason the option to remove the hyperlinks didn't work when I tried waifusearch the last time. It seems not to be a bug, but I don't know why it didn't work the last time. I reposted the article, and I will delete this posting here later. So you might delete yours, if you wish. The new posting is still messy, probably because he didn't use tabs, my copypasta didn't copy them or I don't know.

Robowaifu Technician 10/31/2021 (Sun) 15:40:29 No.13866

>>13724 >>13728 Reliability test of hydraulic actutors (literally working with water) by Automaton robotcs: https://youtu.be/iQhYXE6cAEY This does it for me, I might actually use something like that. Because it's easiely imaginable to reuse the water by catching it with onter tube around the muscle.

Robowaifu Technician 11/04/2021 (Thu) 17:46:01 No.13966

Hasel actuators are something to keep an eye on. They might not be interesting for the face, because of high voltage, but maybe somewhere. >Reminder: Hasel actuators https://youtu.be/PGGQc5q2NGo >Use cases, advantages https://youtu.be/TjglKIkLFSI >Speedtest: https://youtu.be/Lsn-Z1wKaEo >General progress, more stroke https://youtu.be/ep0CV9PYtSo >Accumulation conveyor, efficiency https://youtu.be/bjDdUn39H7s >Fast repetitive movements https://youtu.be/2ggwTlWbkZI >Dev kits https://youtu.be/i1QmwOxGGFA https://youtu.be/LhQgKnkxXXA https://youtu.be/usvoiGBAflY

Robowaifu Technician 11/04/2021 (Thu) 22:49:18 No.13978

>>13966 This is similar to a concept I was thinking of, except my design only contracts like a muscle. Any idea what that "self-healing liquid dielectric" is?

Kiwi 11/05/2021 (Fri) 05:21:39 No.13989

>>13978 All liquids are self healing. Dielectric just means they're insulators. Many HASEL actuators have been made with castor oil and transformer oils because they can handle large voltages. The system works through hydraulics and large voltage differentials causing conductive plates to attract each other. Really, the oil is only a working fluid that needs to easily flow when the plates squeeze it and, withstand large voltages so that shorts don't happen.

Robowaifu Technician 11/05/2021 (Fri) 23:21:26 No.14018

>>13989 >All liquids are self healing. Well, that's obvious, but I'm not the one who called it that. It just seemed like he was trying too hard to make it sound more sophisticated than it actually is. >Many HASEL actuators have been made with castor oil and transformer oils because they can handle large voltages. That's good to hear. The thing I was going to make was very similar, but uses electrostatic repulsion instead of attraction, so I wasn't sure what to use aside from the main electrode. I was thinking of a dielectric powder instead of oil, but I guess either or a mix of both could do. Here's a crude doodle, it's a loop of wire inside a plastic bag with the dielectric. A single HV AC power source charges the loop, so both sides are the same charge and repel. Alternatively I was thinking of just a single wire, half of the loop, with dielectric doing all the repulsion like putting sand or something on the top load of a Tesla coil and turning it on to blast them off, but 'catching' them with the bag to push perpendicular to the wire to create the force. But maybe it would be better to use a conductor instead of a dielectric, for an added induction-levitation-like force? Or go in the opposite direction entirely and rely on wires, for something that'd look more like the other pic.

Robowaifu Technician 11/06/2021 (Sat) 02:40:09 No.14021

>>13989 >HASEL Actuators This was educational: https://www.youtube.com/watch?v=Lsn-Z1wKaEo They are also for sale apparently. What does "self healing" even mean? It sounds like a marketing gimmick.

Robowaifu Technician 11/06/2021 (Sat) 03:13:48 No.14022

>>14021 >What does "self healing" even mean? It sounds like a marketing gimmick. Yeah, I made that joke already. It just means that it's a capacitor with a liquid dielectric, so when the capacitor plates attract and the liquid is squeezed out, it'll "self-heal" by the liquid moving back in once the plates move apart.

Kiwi 11/06/2021 (Sat) 04:01:33 No.14024

>>14018 >It just seemed like he was trying too hard to make it sound more sophisticated than it actually is. That's a polite way of putting it. >Dielectric repulsion That's fascinating. I take it it'll maintain constant repulsion until a drain is triggered. I would always use a dielectric oil for any electric charge based actuator. As you are no doubt aware, they have many advantages over most other dielectric mediums. Incorporating a dielectric powder could be interesting for experiments. Air is an excellent dielectric but, it makes for very weak and inefficient dielectric actuator from my albeit, very limited experience.

Robowaifu Technician 11/06/2021 (Sat) 06:34:59 No.14025

>>14024 I hadn't heard of the Hasel method until this thread, my original idea was inspired years ago by the beginning and end of this video: https://www.youtube.com/watch?v=P5za9sa4-qk but I genuinely don't know enough about electricity to know what would be the best material to use. I've seen people put flakes of aluminum foil on the top load of a tesla coil and they fly off. I've also seen it done with bits of paper, and that video uses sand. I was thinking of eventually doing the same thing with a little tesla coil of my own and just figured I'd try a bunch of things to see what gets the most distance. A lot of my ideas rely on brute force trial and error, because I have no idea what I'm doing. It wasn't even until later that I realized I could probably just use a bunch of insulated wires in phase with each other, (instead of 180° out of phase like Hasel) hence that wire ball pic. >I take it it'll maintain constant repulsion until a drain is triggered. I was just going to use HV AC in an ISM band, and figured the strength of the contraction could just be controlled with amplitude modulation, or maybe pulse-density modulation like a real nervous system. I didn't think about maintaining the contraction by maintaining a DC charge, because you'd probably need to keep putting energy into it just to do any meaningful work.

Robowaifu Technician 11/06/2021 (Sat) 13:23:10 No.14039

>>14022 I'm quite sure they mean if there's a hole somewhere the oil coming out dries and closes it, so it might be flexible when dried, maybe has something like silicone rubber mixed into it.

Robowaifu Technician 11/06/2021 (Sat) 18:18:14 No.14048

>>14039 That would make sense, but I'm not getting that from the diagram.

Kiwi 11/07/2021 (Sun) 03:27:39 No.14061

>>14039 That was never brought up in several HASEL research papers I've read. It's a good idea if you could figure out the appropriate additive to seal holes when reacting with oxygen or nitrogen.

Robowaifu Technician 11/07/2021 (Sun) 03:32:40 No.14062

>>14061 Thanks, then it was just my imagination. Would have been nice, though.

Robowaifu Technician 11/27/2021 (Sat) 02:19:48 No.14513

>>12810 >hasel actuators Would a continuous coil of the circlar disk actuators work? Also, I think the preferred direction of actuators are those that work in tension (contraction) or both ways (bi-directional) instead of expanion. This way, the actuator or string does not collapse on itself in buckling, easier to connect the pulling string, ect. A real muscle works in tension and tendons / joints / bones all work like wires in bowden tubes. I am going to start printing CF Nylon cycloidal gears with PC Max enclosures to make servos in the style of the anti-backlash cycloidal gearbox on hackaday. The carbon fibers, nylon, polycarbonate mix, and maybe some PTFE powder should give me plenty of dry lubrication that doesn't need frequent servicing. I would like to try planetary gearboxes, but I feel that any amount of warping from 3d printing very finely detailed gear teeth would lead to noise and backlash. Cycloidal gearboxes seem to be better optimized for 3d printing BLDC gearboxes at home. PolyMax PC/PC Max, PolyMax CoPA nylon, and NylonX are all higher temperature plastics with anti-warping compositions, and strong as fuck for being printable on entry-level 3d printer machines (all metal hot-end extruders, heated bed, and non-heated enclosures). Machining delrin gears would probably be better strength (~60MPa printed part tensile strength vs 83 MPa delrin tensile strength) and friction-wise. I will have to see how bad cycloidal gear vibration is for low-speed applications like a robutt muscle. If cycloidal gearboxes turn out to be heavy pieces of garbage, I will report back here with results and forge on ahead with planetary print-in-place gearboxes like I planned to originally, before I found an existing model for cycloidal gearbox actuators on hackaday.

Kiwi 11/27/2021 (Sat) 06:39:41 No.14517

>>14513 >Coil of disk hasel actuators Should indeed work, would be complicated to build though. >Contraction is better then extension You are correct. It must be said that unless gravity or a spring is used to provide a return force, you will need to pull both ways. >Cycloidal gearbox Mind sharing the link to the Hackaday project? Cycloidal gears are notorious for vibration, make sure you carefully balance the gears. Most modern designs use out of phase gears to balance out the forces, that can help a lot. Did you design a print-in-place planetary gearbox or, is this design online? Either way, please share links and information. Good luck, cycloidal gears have low backlash and high ratio to area potential, would be good to have as an option for Anons.

Robowaifu Technician 12/05/2021 (Sun) 07:04:20 No.14625

>>14517 >Hackaday cycloidal gearbox project https://hackaday.io/project/167855-simple-cycloidal-robot-leg-for-quadruped Also, >stepped gear planetary gearbox >file related Making a stepped gear in a single stage planetary actuator would give a working gear ratio with high backdrivability and low vibration compared to a cycloidal gearbox.

Robowaifu Technician 12/16/2021 (Thu) 04:31:28 No.14689

I got ahold of a BLDC dev kit (moteus) and tried it out. It is indeed the motor most suitable for human x robot interaction since it is light, backdriveable, powerful, available, long-lasting, and has a large platform of hobbyists doing development work right now. These beat shape memory actuators in precision and ease of use by miles. There's no working fluid, no compressors, no pumps or tubes, and they are ready to have many types of controllers bolted on right from the factory. This is the fastest way to build a good strong motor that isn't a non-backdriveable geared DC motor. The main downsides I'm noticing are that they aren't very cheap at 30-70$ for just a small low torque motor, 60-80$ in controllers per actuator, up to 500$+ for a geared high torque actuator. Also, there's effects at play that make the motor/actuator system surely undesirable for some people: >cost >bulky circular shape >cogging (motor has intermittent torque when the magnets align with the poles) which feels like it has "cogs" as you turn the motor with your hand (not perfectly smooth rotation like you might want) >noise (quiet static and grinding noise from electronics) >rigidity by virtue of being solid >backlash if using a gearbox with small motor >high inertia if using a big direct-drive motor If you don't care about the trade-offs, I'd recommend a BLDC + Controller system. I have a gearbox in the works to bolt onto the motor to see if 3d printed planetary gearboxes will work. I'd also like to see if there's a coreless/ironless/slotless motor that would be able to direct-drive a large surface (thighs) smoothly.

Robowaifu Technician 12/16/2021 (Thu) 04:48:26 No.14690

>>14689 One last thing I forgot to mention is the potential that low KV gimbal brushless motors have. They are used for camera panning, and have significantly higher coil turns/resistance, so they cannot have position accurately measured in the same way as some BLDC controllers are set up. The potential benefit is that they are cheaper and run on lower current that can be pumped out by cheaper controllers and power supplies.

Robowaifu Technician 12/16/2021 (Thu) 06:23:22 No.14691

>>14689 Thanks for the nice breakdown Anon, it's appreciated. I'd say cost is the most obvious (and limiting) factor for the significant majority of us. I hope we can at the least find alternatives for pricey single-use controllers, and spread the costs out among fewer, general-purpose drivers. >coreless/ironless/slotless motor What does 'slotless' motor mean?

Robowaifu Technician 12/16/2021 (Thu) 17:13:55 No.14694

>>14691 Please use "ctrl + f" to find information in the relevant thread. Slotless means coreless and that's been explained before in this thread. Picrel for more info

Robowaifu Technician 12/16/2021 (Thu) 17:51:49 No.14695

>>14694 Ahh, I see. My apologies for appearing lazy. I would guess the little micro motors in tiny drones are of this type. I know they get pretty hot, but the RPMs achievable are frankly, amazing. Again, thanks.

Robowaifu Technician 02/01/2022 (Tue) 00:36:46 No.15126

Anyone have any updates to building a robot actuator?

Chobitsu 02/09/2022 (Wed) 09:18:31 No.15174

>>15126 I'm not really aware of anything new on that front Anon. I expect we'll have something before long though.

Robowaifu Technician 02/24/2022 (Thu) 21:21:04 No.15313

>>15174 I'm making a nylon gearbox for the best feasable actuator mentioned in >>14689. I have about one or two more weekends until it is prototyped. This same actuator could even be applied in any other system for cheap power and precision.

Robowaifu Technician 03/29/2022 (Tue) 13:06:36 No.15735

In >>1002, there's some links to some decent looking electromagnetic actuators that are fairly simple to build. They're limited in that they only switch between two states, and do so quickly, without a smooth transition. I'm hoping to adapt them for arm and neck mechanisms in a mini robowaifu, and the current plan is to use a small spring and variable current to try and produce a finer position control/state transition. That said, this seems like an over-complicated method, so would anyone here have some recommendations for alternative avenues of consideration?

Chobitsu 03/31/2022 (Thu) 04:22:22 No.15741

>>15735 I think we'll probably find plenty of uses for fast-acting, linear actuators Anon. I hope to see work here along that line, thanks! >>15737 >DC motors are the easiest. Just get a gear motor that exceeds your torque requirements and add a potentiometer to control position or, just use a readily available servo. Good thinking, Kiwi. Can you sort of diagram that for us? I think I understand most of the general points there, but I probably lack understanding in some of the details.

Robowaifu Technician 04/14/2022 (Thu) 14:13:03 No.15878

>>15313 I've made a gearset prototype from 3d printed nylon, and it's garbage. However, I will be tweaking it and trying to make a wolfrom stage planetary gearbox the same way. Here is a paper which has some details (key points: human-safe, high backdrivabilty, high gear ratio, small size) https://ieeexplore.ieee.org/document/8867893

Robowaifu Technician 04/14/2022 (Thu) 17:21:24 No.15879

>>15878 Any chance you can post pics of your WIP Anon?

Robowaifu Technician 04/16/2022 (Sat) 17:44:31 No.15891

>>15879 >>15890

Robowaifu Technician 04/16/2022 (Sat) 21:49:17 No.15895

>>15891 Thanks!

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