Dissadvantages of Suction?

[Dumper FTW 435]

This year my team is experimenting with a suction system for our robot. We're using venturi's and a suction cup to pick up the tubes. In our testing, it works great, and the seal is strong. But we have to keep the compressor going the entire time to keep up with the loss in air pressure, and we're afraid that our battery will die quickly. We are getting 3 new batteries this year, and we have several batteries from past years (although most of those are going bad). Our main concern is that we won't be able to charge our batteries quick enough between elimination matches (if we get into the elimination matches).

Can everyone voice their thoughts?

I like the idea of suction. It's simple to build, and inexpensive (we already have the parts). But many of my team are worried about the battery

[liam.larkin]

You make a valid point and I have seen problems before us in 2005 we used venturi and barely got through a round on one battery. So my recommendation is go to eSTOP Robotics LLC website. They are underwritten by a first team outside of Philly they sell a device called the Custom Control Interface. Using this and some simple codeing your driver or operator could turn the pump on and off as they see fit. So when you are running around not holding a tube you could turn the compressor off. This might save enough power. Just a thought

I would speak to the eSTOP people first ofcourse. I believe they use this exact function on their own robot so they would be able to tell you in more detail.

[j.cole]

Weight is one thing (compressor, air tanks) unless you already have a pneumatic system in play. Another is reliability, will it always grab the tube. Strength, if you get pushed is the seal going to break. Maintenance, leaks air hose coming undone.

Everything has its advantages and disadvantages so in the end its your call.

[Joe G.]

Also, remember that this year, there are no limits on pneumatic accumulators. Having a large reservoir of air available to you, and a fully loaded system at the start of a match, can cut down on the required compressor run time.

[Dumper FTW 435]

Originally Posted by j.cole

Another is reliability, will it always grab the tube. Strength, if you get pushed is the seal going to break.

That was our main concern when reviewing suction. Personally, I doubted that it would work. But the tubes stuck really well (we had one person hold it up with a venturi while other people acted like robots and tried to knock it down) and it sealed perfectly as long as we had a high enough PSI

[Dumper FTW 435]

Originally Posted by liam.larkin

I would speak to the eSTOP people first ofcourse. I believe they use this exact function on their own robot so they would be able to tell you in more detail.

Thanks, I'll look into it

[Jon Stratis]

For what it's worth, we looked at suction pretty hard in 2007, and ended up abandoning the idea. We could never get a system together that could reliably pick up the tubes without requiring extreme precision, and the battery requirements for it are pretty intense. We've steered away from suction ever since.

[camaro 20]

my team tryed out a suction system where we used a shop vac and a mask used in cpr. the suction held when we shook the tubes back and forth but only would drop when we turned off the power. one of the proubles we had was going in with a suction method you had to grab the opposite end of the tube.

[thefro526]

The disadvantage of Venturi Driven suction is that it requires a Pneumatic System to function which means you're adding a minimum of an extra 10lbs or so if you have the compressor on board and a reasonable amount of air tanks.

There are other options available to create a reliable vacuum driven mechanism, perhaps the most common is to take a commercially available vacuum impeller and retrofit one of the KOP motors to it. The motor only has to run while you need the vacuum, which should draw less power over the course of a match than a compressor. This method has been used by teams in the past to hold Soccer Balls, Track balls, and Tubes so it's proven as long as you can get your implementation right.

One of the downfalls of suction is that the surface of the object has to be relatively uniform which makes positioning key. You may or may not be better off pursuing another option.

[Dumper FTW 435]

Originally Posted by thefro526

take a commercially available vacuum impeller and retrofit one of the KOP motors to it.

We have considered that idea. What would you suggest we try? I know a lot of teams have used shop vacs in the past

[thefro526]

Originally Posted by Dumper FTW 435

We have considered that idea. What would you suggest we try? I know a lot of teams have used shop vacs in the past

To be completely honest, I don't really know. Most of the systems I've seen have used a shop-vac or other heavy duty vacuum.

[Chris is me]

Buy a shop vac from Home Depot and take it apart and you should be good. I don't have a specific model, but I heard that the model 228 used basically came ready for an FP motor retrofit out of the box.

That said, I would make sure you put a lot of thought into your cup design to make sure you're getting the best possible hold on the tube.

[IndySam]

last year we just ordered the impeller from the manufactures replacement parts website.

[Sunshine]

Ryan:

We used a vacuum system last year by making our own impeller. We took apart an 18volt hand-held vacuum and re-engineered their impeller for our purposes. It was created in our 3D printer at school. It worked great. I have enclosed a few picts of the system. If you can use the CAD files, I would be happy to pass them along.

[Vikesrock]

It should be noted that there will be significant differences between an impeller based system and a venturi based system as described here. You may not be able to get the same strong hold with an impeller based system.