Tote Grapping Strategy
 

I have a concept for grabbing totes and bins and I want to hear what everyone else has to say about. If you have any comments, questions, ideas, or any other advice please comment. Any advice will be appreciated.
My idea is to use a piston connected to a motor via a chain and some suction cups with tubes connected to the piston. When the suction cups are pressed up against the side of the tote or bin, you turn the motor on, so it pulls the chain in, making it pull the piston along with it creating a vacuum. Since the other end of the piston is connected to a tube which leads to the suction cup, the created vacuum will pull on the side of the tote or bin holding it in place so that it can be picked up and moved around. There will be two of these vacuum suction cups on either side of the tote/bin so that the tote/bin will be stable when picked up, and will not fall off. This can make stacking totes easier because there is nothing underneath of the crate when the robot grabs it, so the robot can place the tote directly on top of another, making it less likely that totes on top will fall off.

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I am not your team engineer (ianyte), but:

You could get that to work I think sure - it would be a lot like those mechanical suction cups you use to mount go-pros and GPS. The major challenge will be making sure you get a good initial seal with the suction cups. If any air leaks in as you draw the cylinder back, you'll lose any vacuum you created, and you'll reach the end of the stroke without any grip on the tote. This will be double challenging given the totes have textured, corrugated sides. Maybe if you had some mechanical way to press the seals tight before drawing the vacuum.

Also, as bvisness points out, there are easier ways to lift the sides of a (right side up) tote.

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This is simply bologna

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I agree with the devinator:deadhorse:

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Personally, I think that using suction cups will prove promising on the totes. It wouldn't matter if a tote was upside down or right side up. But I foresee them being more difficult on the bins, because they are curved and somewhat flexible. With all that in mind, creating a bot that uses suction cups would easily win you the Xerox Creativity Award. It is one of those things that few teams would see to fruition.

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:D https://www.facebook.com/video.php?v...27568399870724

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Do not use suction cups to try to pick up the totes or cans - you will thank yourself later.

, Bryan

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Yes, listen to one of the original teams, its probably a good idea.

While this is indeed an interesting (and functional if done right) idea, there are far more effective ways to manipulate a tote/can. Do I hear scissor lift anyone? (Just kidding)

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Now that is a manipulator....Bring your own Semi-Truck Scales...Watch him go 3D Print it to lighten it up and get it to actually work. What is the vaccuum pump on that BTW? We had fun w/ a leg lamp too, but, they could actually play the game with it also.

He'll be the one to figure out how to turn over every one of those flipped upside down Grey Totes easily and be able to push all the totes to you to stack, and cap the stack in Auto, and everyone will be clammering for him to join their Alliance...Lol.

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There might actually be a simpler method of generating that suction, if you do indeed decide to go that route. Assuming you're already using pneumatics, replace the motor/chain with a pneumatic cylinder that will be fully retracted(or extended, depending which port you use) when suction is being applied. Ideally, you'd have a small(er)-bore cylinder pulling a large(r)-bore one with one port set vented to the atmosphere.

This method has been used before, with some success, on exercise balls. Whether it'll generate enough vacuum on totes is left as an exercise for whoever wants to experiment (I happen to not know the answer either, though I suspect it would).

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One of our students spent an hour with a hack saw and a chunk of plywood, and made a neat gizmo that fits the side of a tote and lets us lift it up. No moving parts. It's not very impressive looking. But it works.

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I agree with having nothing under the totes, that certainly makes stacking easier. Our team is designing a mechanism similar. In my opinion, however, this design seems rather complicated, or at least unreliable. Ideally, a robot should have something that works the same every time. I speak from experience, due to the massive ice storm that affected part shipments for our team last season, our device for manipulating the game piece last year was rather shoddy and didn't work consistently. Don't let me spoil your ideas, however, because everything can be worked into something perfect with enough time.

Very clever OP but aren't you overlooking the fact that the totes have handles. My advice is KISS.

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Could it work? Sure, if you grab the flat, smooth parts of the bin and no one man-handled that tote in any of its previous matches to leave a gouge. If you do decide to proceed down this path, make a prototype quickly, because this is one of those "you don't know what you don't know" problems, and the only way to find out what you don't know is through fiddling with it.

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Speaking from experience I think that if you could pull it off, you'd better to do it really well. Because if you do go this route and your only okay at picking them up, then you have spent much time and effort into developing a mechanism that may or may not win you any awards or alliance selections. I personally don't think that the suction cups would be able to handle the weight of very many totes, or get simply bumped around enough while driving, to maintain suction. Just like in a car with a GPS system, if you hit a hard bump or swerve out of the way, or maybe even turn to sharply, you will lose the suction and then all your totes fall. But if you could do it well it would be impressive and memorable.

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This year more than most, every robot on an alliance must contribute to the scoring in some way in every match or will be written off come alliance selection time. Mercilessly test your prototype as soon as you can since you will not have the luxury of drawing on the experience of other teams. After you are done trying to make it fail in every way possible, have someone else try to make it fail. If it still is reliable, you have a great way to pick up the totes. If not, you hopefully have enough time to implement a different way to pick up totes.

Please note that I do hope that you succeed in this since it would be really cool to see an alternative way of playing the game.

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Easy and cheap to prototype.
http://www.harborfreight.com/4-1-2-h...cup-40993.html

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We did a curved rectangle suction test using thundercord as the seal, a pneumatic tube hard mount as the port to draw air out, and a pneumatic cylinder as the vacuum generator. It worked really well with human hands. It lifted that RC up quite nicely, even when the vacuum was placed at the very bottom of the RC and rotated up from a laying down position.

We then started to work on what it would take to get a good seal around a recycle bin every time with a robot. It is these auxiliary components which start to make everything complicated, since the two basic requirements of the overall mechanism aren't met without some serious extra 'stuff'. All told, it would take 8 buttons just to drive this mechanism, and it isn't even the primary mechanism (ironically that one only takes 2 buttons...).

We haven't written the concept off yet, but we did do a pros & cons list. Most of the cons are about complexity in one dimension or another, which tells me the design is very likely to be unreliable if we try it. We have some other designs which use some features that are similar to the auxiliary components of the suction design, so we're moving forward with detailing the little things out first.

If you do decide to go in the suction device direction, keep in mind the simple movements of the robot, and the workload you'll put on your driver.

The only advice I'll give outside of that is to not use suction for totes unless you have great drivers or a great alignment/counter force mechanism.

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Personally, I would be worried about two things with this design:

1) Having a piston moving up and down on the robot using a chain. Is it possible? Yes. Would it be very difficult to get to work, especially for a relatively new team? Definitely.

2) Using suction cups. The design could work, but the totes would have to be in exactly the right place to be grabbed (not near handles or bends in the plastic), which is not going to happen often in real life.

None of the designs that our team suggested required anything more complicated than a two-motor setup, and yet we found seven different ways to get a four-to-six-tote stack, with three of them able to grab a recycle bin as well. This design would be kind of overly complicated, considering the fact that it could really only grab and carry a single tote at a time.

That being said, this is a clever idea. Best of luck on whatever design you end up choosing.

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We used an old suction device at the end of a small shopvac and found that it can form a nice seal on the flat portions of the totes on either short end (where the FIRST logo it). You would still have to find a way to raise the totes and control for rotation of the tote as you raise them (similar to how many hook designs have to control for rotation), but it's potentially do-able. We will not be pursuing this design further, though. We liked our other prototypes more, for numerous reasons.

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This thread might fit better in a more robot-focused board rather than one devoted to game-play strategy, but that's just me ::rtm::