4

The uArm is a robot arm with a suction cup (or gripper). I'd like to try to make just the suction part of it, and I'm wondering what components I'd need?

By the looks of it, I'd need a hobby vacuum pump, but these seem few and far between on UK components sites.

How would I power it? It looks like they're all 12v, and I believe Arduino gives you 5v?

Exact what components would I need? Do I need any shields?

Here's a short video of the suction cup I'd like to copy:

10
  • What do you need to grip (i.e. how heavy)? May 18, 2014 at 1:36
  • @AnnonomusPenguin Very light; one suction cup above and one below a thin plastic bag to pull it open (they're thin and tight together - this was the best way I could think of to open them). May 18, 2014 at 1:37
  • You, of course, could open it with fire... :D If the plastic bag has a long area above the "zipper," you might be able to make some sort of hand contraption, which might work better. May 18, 2014 at 1:39
  • @AnnonomusPenguin The bags don't have zips. Just one open edge and one sealed edge. They're not the easiest to open until you get the nack of it. Suction would definitely be better I think. May 18, 2014 at 1:41
  • 1
    may I know What are the components called in that video called? What are the approximate specifications for this parts ? Jun 13, 2019 at 14:23

3 Answers 3

4

Just a note for those who wonder the same and are in need of a vacuum: In theory, you can use Venturi effect (or Bernoulli's Principle; it's basically the same) to create a vacuum. Or go buy an Aspirator pump. Since English is not my native language it's difficult for me to explain it in my own terms, but I'll try to give you a rough idea anyway. (Google it or feel free to answer with a better explanation).

First you need some flow of a fluid or gas (air from a compressor or water from a household outlet are fine). You pass that flow through left-to-right in a T-pipe (I'll call that the "flow pipe"). This will result in a weak vacuum in the orthogonal pipe (I'll call this the "vacuum pipe"), which you can connect to your suction cup.

The strength of the vacuum depends on the pressure in the "flow pipe". That means a higher velocity of your matter in the "flow pipe" is good (either a stronger compressor or smaller diameter of your flow pipe).

If I understand my physics book correctly, a higher density of the matter in your flow pipe will also produce a stronger vacuum. If you need a really strong vacuum, you could even use a water compressor, i.e. high pressure cleaner; but I suppose even a small air compressor will outperform a household water outlet (and you could toggle it from an Arduino with a relay board).

Since the air in the vacuum pipe expands more than many other materials, you could try to replace it with i.e. oil (be aware you'll pull out some of the air/replacement material at the intersection in aspirator!). This optimization is dangerous with a normal vacuum pump, since these usually break when sucking up fluids into their internals.

Also using an aspirator has the upside of not needing to buy a vacuum pump if you already own a compressor. On the other hand, that setup might be even louder (and possibly less efficient) than a dedicated vacuum pump.

1

There are two approaches I can think of that would work decently. Either a.) suck air out of a "cup," turning off the pump when done. OR b.) have a valve where the arm pushes one part of the bag against the table to squeeze all the air out of it, and shutting a valve attached to the "cup." Then, to release, the valve could be opened. For the suction cup, I'd personally try making it out of a suction cup hanger like this:

Source: http://www.amazon.com/Set-Large-Suction-Hanger-Hook/dp/B00439SCZO

The availability of these might vary by area, so I'm not sure how common these are in the UK. If you find one, make sure that it's pretty thick, with not that large of diameter so it's not too big to work with. I'd then remove the metal hook with pliers and drill a hole in the center. After that, you would need to superglue a tube through the center of the hole and seal it with some caulk.

Like I mentioned earlier, the two options are to a.) suck to grab and turn off pump to release or b.) have arm apply pressure to a flat surface and then shut a valve attached to the tube, creating negative pressure in the suction cup. Then, you could open the valve to balance the pressure and let the item go. I'd personally do the suction approach because, although it is louder and might use a little more electricity, it's a bit easier to build and execute and can grab in the air. I'm going to focus on that.

For the pump approach, build the suction cup (like I said above), attach the tube to one end of the motor with a hose clamp, leave the other hose terminal unconnected, and connect the pump (through a relay) to a 12V 1A+ power supply. You can do this by connecting the + pin of the pump to the "out" (or similar) pin of a relay breakout board, the "in" (or similar) of the relay to the power supply +, and the - of the pump to the power supply's - wire. This will make a circuit similar identical to a switch (the switch being the relay). To connect the relay to the Arduino you will have to connect the relay's logic signal to a pin on the Arduino and then you can just write HIGH or LOW to turn the pump on and off.

EDIT: Forgot to mention, you can use a transistor, too. Also, I illustrated the second method (hopefully it makes this clear).

6
  • So there's no way to have the pump on the same circuit without a relay? Your last paragraph is what's relevant to me. It's more the electronics I need help with. As for "squeeze all the air out", I'm not sure what you mean; there is no air whatsoever inside the bags. They're flat - only 1-2mm thick. Thanks for your answer, it's useful! May 18, 2014 at 2:04
  • Actually you don't necessarily need a relay to command the pump, a transistor could be enough, depending on the current needed by the pump. The important thing is that you need a separate power supply (12V if this is what the pump needs) than Arduino 5V output.
    – jfpoilpret
    May 18, 2014 at 10:03
  • @Danny You'll need a relay or transistor; the Arduino can only supply 4% of the current needed and 46% of the voltage needed. I haven't worked with transistors that much, so I can't advise you on that. As for the squeeze all the air out, I meant pushing the suction cup against a surface so the air in the suction cup flows out, through the tube. Then, when you would close the valve, it would try to expand, thus creating negative pressure between the bag and the cup. I'll try making a picture. May 18, 2014 at 14:47
  • I am afraid the second method would require to exercise a high pressure first on the object to hold, that may need an engine even stronger than a pump! I think the vacuum-pump is more reliable here.
    – jfpoilpret
    May 18, 2014 at 15:29
  • @jfpoil Yeah, it was a last minute kind of idea. If it works like I imagine it would, then it would need only slightly stronger arm motor. May 18, 2014 at 16:17
0

You can't power things like pumps and motors with the power supply from an Arduino. It doesn't provide nearly enough current. It's meant for providing regulated 5V for low powered logic circuits, and nothing else.

What you can do is use a transistor as a switch to turn on and off the power from a suitable external power supply.

If you find a vacuum pump that runs on 12V, get a 12V power supply with enough current to drive the pump, and then use a MOSFET transistor (example link) that will can handle enough current at 12V and can be controlled by a 5V signal to it's gate, and use that to switch the power on and off. Then you'd need a diode to protect the transistor against the reverse current you get from inductors like motors.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.