9 ms·
A home made PCB stepper motor
- cushychicken 5y agoThis is incredibly cool. The research video showing the little "robots" placing drops of glue to assemble carbon fibers is AWESOME! I haven't been this excited by an internet video in months. My immediate thought: how could this be used to make a really cheap desktop pick-and-place system?
- jacquesm 5y agoGet it to make more little robots! Even smaller ones...
- kragen 5y agoMagnetic drive is poor below the micron scale, but you could switch to electrostatic. No equivalent of diamagnetism to draw on tho.
- nynx 5y agoThere’d have to be some way to temporary bond components to the bots. Regular pick n’ place machines use suction.
- jacquesm 5y agoPut the whole thing in the dark, small solar cells on top and then short circuit them through a coil, that could power a tiny gripper whenever they are lit up.
- ncmncm 5y agoSteer a laser beam over to the robot.
- cushychicken 5y agoI imagine having two little microbots working like tweezers. Theoretically, it's possible to manipulate the field to make one of the robots rotate. Two magnets rotating in tandem could make something like a tiny pair of tweezers.
- jacquesm 5y agoOr have them be asymmetrical, one has the half-tweezer at the left side the frame, the other at the right.
- amelius 5y agoThe problem: there is solderpaste on the board before placement. Therefore, you have to bring the components to the board from above and push them into the solder paste. The suction based pick and place machines are well suited for this task. Tiny robots walking over the board (with lots of obstructions such as solder-paste and through holes) are not such a good match.
- nynx 5y agoActually, I bet this would be possible if the bots had a tiny magnetically actuated suction piston. You’d have to figure out how to create electromagnetic force in the z-direction independently from the x-y force though. Not sure if that’s possible. Heavy components could be held by multiple bots.
- ncmncm 5y agoSuspend the board upside-down above the robots. They just need to smoosh parts on from below. I.e., not practical, but fun to think about.
- cushychicken 5y agoWhy couldn't the bots apply the paste as well? I think of this being a tiny version of a home SMT assembly where you're dispensing paste and placing components manually, one at a time. I also suspect that you can have the target PCB separate from the one the magnets move on.
- goodpoint 5y ago> pick-and-place system Most likely not, but bio/chemical experiments yes.
- gww 5y agoThere's a YouTuber named Stephen Hawes[1] whose made his own pick and place machine. [1] https://youtu.be/6Sa9jNhaRbg https://youtu.be/6Sa9jNhaRbg
- cushychicken 5y agoYeah, but Index prices out at like $500 plus labor to put it together. This has the potential for: * way less material cost * way less assembly, and * way higher reliability due to fewer moving parts
- jacquesm 5y agoAnd potentially higher repeat accuracy because you don't have the rotational joints to deal with. Those are pretty lousy when you get further out from the axis of rotation.
- bsder 5y ago> My immediate thought: how could this be used to make a really cheap desktop pick-and-place system? The limitations of homebrew pick-and-place are the vision system, not the control system. If you solved the vision system problems, you could probably build a pick-and-place out of Legos.
- aspenmayer 5y ago> If you solved the vision system problems, you could probably build a pick-and-place out of Legos. Someone made one, and it’s amazing. https://youtube.com/watch?v=LHsl9jSOO6M https://youtube.com/watch?v=LHsl9jSOO6M
- jcims 5y agoVery cool. Might make for a fun chess board or model train/model city layout. Edit: Glad he mentioned Carl Bugeja's youtube channel, this instantly brought Carl's work to mind.
- nvalis 5y agoThe model city application is indeed currently developed [0] at the Miniaturwunderland [1] in Hamburg, Germany. [0] https://www.youtube.com/watch?v=xPUEOhMBpUw https://www.youtube.com/watch?v=xPUEOhMBpUw (in German) [1] https://www.miniatur-wunderland.com/ https://www.miniatur-wunderland.com/
- jacquesm 5y agoThat first video is amazing, what a dedication. And they got it working in the end. Super impressive.
- amelius 5y agoHow many robots can you move independently though (all moving in different directions or staying in place)?
- prox 5y agoWould you need to if they can move at 36cm/s ?
- jcims 5y agoSeems like any magnets on the same coil will move in the same direction. So it boils down to how well you can isolate the coils and/or orchestrate their motion so they aren't sharing a coil when you don't want them to be. I wonder if you could use induced currents in the pucks instead of permanent magnets to create the opposing force. Then you could tune the PCB coil to target specific elements. So 212kHz moves puck A, 241kHz moves puck B, etc
- jacquesm 5y ago
- jacquesm 5y agoWow, actual innovation. Amazing stuff. And that video is from 2014!
- convolvatron 5y agothe Sri demo shows 2d motion. pcbs make it pretty straightforward to have an X and a Y array, but for some reason it doesn't seem to me like you can just easily drive both axes independently. could you really tune a 'step' to be on an arbitrary slope?
- jacquesm 5y agoI'd say that depends more on how much you are willing expend on hardware to drive it. You could slice your coils into tiny segments (essentially: just the tops) and then use the back of the PCB to drive them. They'd be magnetic pixels. Maxels?
- convolvatron 5y agogood idea - but that's alot* of drivers
- jacquesm 5y agoYou might be able to do something here along the lines of row and column addressing of DRAM.
- HeyLaughingBoy 5y agoIf you move X,Y separately but with a small enough step, it would be virtually indistinguishable from moving along the slope.
- jacquesm 5y agoInteresting challenge, can you 'microstep' along two axis at once without losing sync? That would be neat. I think I've worked out a way to rotate them as well!
- HeyLaughingBoy 5y agoI would imagine so; it should be the same problem as helical interpolation, but confined to two axes. https://infosys.beckhoff.com/english.php?content=../content/1033/tccncprogramming/html/helicalinterpolation.htm&id= https://infosys.beckhoff.com/english.php?content=../content/...
- jcims 5y agoMy eyes weren't cooperating with the illustration from the Theory section, animated it here (author is free to use of course) - https://imgur.com/a/hVYWBB2 https://imgur.com/a/hVYWBB2 (note that i reverse a few frames in the loop to be less jarring visually, the current is probably not correct when the puck is moving left)
- nvusuvu 5y agoIncredibly helpful to conceptualize what is going on. Thanks!
- a9h74j 5y agoHelpful. Another thing to notice: You don't necessarily need a pcb. For small demo purposes you could close-pack one layer of serpentine insulated wire, then a second layer of a second serpetine wire. There would be a height difference, but perhaps not more than with a two-layer pcb.
- tommiegannert 5y ago> Next steps: Levitation / sliding enhancements I wonder if vibration would help reducing friction. I.e. superimposing a low-power high-frequency component in the field to avoid static friction.
- hwillis 5y agoPedantic: this isn't a stepping motor, it's just a plain linear motor. Stepper motors have multiple teeth per pole: https://en.wikipedia.org/wiki/Stepper_motor#/media/File:Stepper_motor.jpg https://en.wikipedia.org/wiki/Stepper_motor#/media/File:Step... The rotor has slightly fewer teeth than the stator, such that one "electrical rotation" (each coil being switched on in sequence) causes the rotor to advance by the number of missing teeth. That is what makes a stepper so precise; it gets 4+ divisions per tooth.
- marcosdumay 5y agoIf you can lock the movement into a specific position and it's repeatable because of the geometry of the motor, it's a stepper. Yeah, of course it doesn't have the same design of the steppers you buy around. That's obvious from the title alone. That doesn't make it not a stepper. And yeah, it's less precise than the ones you can buy¹. That should be expected too. 1 - Although, that conclusion is way too simplistic to make. It has a different kind of imprecision, so depending on how you compare, you may as well conclude that it's more precise.
- hwillis 5y ago> If you can lock the movement into a specific position and it's repeatable because of the geometry of the motor, it's a stepper. BLDC, series wound, and switched reluctance motors will also hold their position. Cogging torque exists in the majority of motor types. It is not very useful for dividing motors into families, and is certainly not specific to the group of machines called stepper motors. If you energize each coil of a BLDC, series wound, or SR motor (not the wires, each actual coil) in sequence, the shaft of the motor will rotate once (or very close to once). If you do the same with a stepper motor, the shaft will have turned 22.5 degrees or less. It is possible to make a linear stepping motor. The Vernier scale is basically stepping as applied to measurement. This is not that.
- jacquesm 5y agoEqually pedantic: it functions as a linear stepper motor, therefore it is a stepper motor. That it doesn't have a platen is not relevant. Being a stepper is not a statement of precision, it is a matter of principle, does the movement occur in discrete steps or does it occur by continuous movement through a magnetic field? This is a stepper by any practical definition.
- agumonkey 5y agoMan magnetic fields are so fun to experiment with. These, or magnetic locks, so "magical"
- jacquesm 5y agoIf you have a bunch of magnets lying around have a look at Halbach arrays.
- buescher 5y agoWow; I knew something like this was possible since we've all held refrigerator magnets and such that obviously had oddly arranged fields, but I only had the vaguest idea. Thank you.
- jacquesm 5y agoHalbach arrays and some correction coils can be used to make a passive magnetic bearing (long sought after holy grail). They are super interesting.
- agumonkey 5y agoI've seen that a few years ago, for denser motors. Do they have any other use ? Thanks for the suggestion nonetheless
- jacquesm 5y agoLevitation through forward motion, passive magnetic bearings, what's not to like?
- amelius 5y agoDifferent principle, but it reminds me of OpenDrop: https://www.youtube.com/watch?v=pSls9L_h3Q0 https://www.youtube.com/watch?v=pSls9L_h3Q0
- amelius 5y agoIt also reminds me of: https://www.youtube.com/watch?v=9k7zywli4Vg https://www.youtube.com/watch?v=9k7zywli4Vg
- phkahler 5y agoI have wanted to do exactly this concept controlled via RPi with voice recognition to make a real ouija board. I only mention it because I will realistically never get around to it myself.
- deleted 5y ago[deleted]
- lqet 5y agoThis strongly reminds me of the ongoing efforts at the Miniatur Wunderland in Hamburg [0] (a very large model railway) to implement a model Formula 1 race track on which tiny race cars can move completely freely [1]. [0] https://en.wikipedia.org/wiki/Miniatur_Wunderland https://en.wikipedia.org/wiki/Miniatur_Wunderland [1] https://www.youtube.com/watch?v=xPUEOhMBpUw https://www.youtube.com/watch?v=xPUEOhMBpUw
- sen 5y agoThat is ridiculously cool.
- genmud 5y agoElectromagnets are cool.