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How to pick up a frisbee
My team (4183) has been having trouble deciding if we want to make our robot able to pick up Frisbees and if we want to how can we easily pick them up and deposit them in our shooter.
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That plunger and racket idea looked pretty good to me....
On a more serious note, one idea we had was using a dustpan-like mechanism to get under the frisbees and flip them into our hopper. |
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the simplest solution i could think of was to pick them up like you'd pick up a basketball. just use rollers to suck it up.
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That's the easy part. The hard part is determining which way they are facing, and then how to flip them.
I think that picking up the frisbees is going to be a waste of time. There's a pretty small number sitting on the field, and the main way to get most of the frisbee's is through the feeding station. However, I was thinking of a conveyer system which would have a little hatch open. Above the hatch would be a suction cup on a piston. It would go down, pick up the frisbee, then deposit it on the conveyer belt. Simple and fast. Doesn't solve the upside down issue though... |
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One solution is simply to ignore the upside down discs and just go for the ones that are right side up.
On that note, however, does the manual explicitly state that the discs on the field at the beginning of the match are face up? I assume so, but I can't find a specific rule. |
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I think it's quite possible to build a launcher that will toss discs equally well when they're upside down as right side up, or near enough that there isn't a noticeable difference at the type of ranges you might see in this game. I've heard a human throw type called the "Hammer" or the "Tomahawk"; it goes from vertical to inverted in flight and stays inverted. It also travels a fair ways, if thrown correctly.
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I was wondering..Would it be completely legal to back up against the deposit slots and have them land in a hopper right away?
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yep
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Perhaps have a toilet plunger end on a pneumatic arm come down and stick on the disc and then pull it back up. On the way up, the disc would hit a mechanical stop and fall of the plunger into a ramp or hopper.
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Re: How to pick up a frisbee
I'm not so sure a toilet plunger would work so well....for one thing, the suction isn't actually that great. The hard rubber pretty much prevents that. I think the best thing is to just use a dustpan-ish mechanicsmand drive around with that.
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You could in terms just build an arm that has a tray of sorts and just dumps 3 at a time?
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a cool plunger pickup system |
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Seems to me that if you got it going good enough, an upside down discs does nearly as well. - Sunny G. |
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http://www.youtube.com/watch?v=iyE4Ir6dkY8 |
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I'm not sure that picking up discs off the floor will be very important, but this is something I hope to see on at least a few robots.
http://www.diginfo.tv/v/11-0121-r-en.php |
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Don't assume this video proves anything. |
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From the accuracy of prototypes and the large size of the goals, I don't think that good teams are going to be missing many shots. In addition, as I learned last year, just the driving to pick up game pieces requires great precision and can be time consuming. It seems easier to zip back to your driver station and quickly load 4 more from that hard-to-deplete supply.
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Yeah, our team initially planned to do a mechanism to pick up discs from the floor but..
Guys lets be honest.. each team on your alliance gets 17 discs. I think in the 1:30 tele-op (not including end game) it's very reasonable that you'd be able to traverse the field to your hopper, get filled, go back, score, and repeat to get pretty much just those 17 discs in (if even). In other words, don't worry about picking up discs. Go get filled because it takes attention off of picking up and elevators and focuses on filling some hopper on your robot that'll go straight into a shooter. In 1:30, I can't see getting more than 17 discs across anyway. If you do, that's excellent, just be happy with that! |
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To all teams reading this, make sure that you test any prototype on carpet similar to that being used on the official field.
A design that might work on your shop floor could very well fail on carpet. In addition, I think teams should look at how many shots missed the hoops last year. Expect about that many disks to miss their target and end up on the ground. |
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Sure it's much easier to go across the field to your alliance's feeding station and grab four discs, but think about it. After autonomous mode, you'd have 3 robots fighting for discs at the alliance feeding station. Sure there's enough slots for all three to be filled at the same time, but realistically, all three would not be fed at the same time, as the corner is very small and can barely fit all three robots there assuming that they are average sized. Plus, you have to worry about d-bots getting in your way and defending your feeding station. If you can pick up discs from the ground quick enough, it would be a HUGE advantage to you, and it would be beneficial during autonomous too, because then you can pick up discs from the ground and shoot them during auton for additional points (after you've shot your preloaded discs). And as for there being a lack of discs on the ground, the goals are fairly large but with the amount of defense that's possible, I can see a LOT of missed shots when a d-bot knocks a scoring bot off of alignment. We saw this last year with fender-shooters and d-bots.
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Re: How to pick up a frisbee
When I first saw the animation I thought that it would be hard to pick them up off the ground, then when I saw that we would potentially be suspended 90in. In the air, I quickly said, good shooter, good arm, no pick up. Yes if your alliance gets 17 frisbees each that means why pick up when you can just recieve. Just my honest opinion. Just remember this year, the lower the weight the easier the climb.
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Could a robot block the path to the feeder station by just sitting there?
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But, as is popular, "assuming makes an $@#$@#$@# out of you and me". At least for my team, this warrants a couple of runs through our prototypes. - Sunny G. |
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I forget which rule, but your robot can't purposefully block an area of field and then they aren't allowed to touch your robot when they are at the feeder station.
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I get the feeling that this is going to be the biggest argument of the build season.
I personally think that our second-year team is better off not trying to get them off the floor, and instead concentrating our efforts on building a feeder-fed bot in three weeks and practicing with it for the next three weeks. That will allow us to be consistent scorers, so we won't be littering the field with frisbees. It will also get us ranked highly in the qual matches, which is where we want to be. |
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Violation: TECHNICAL FOUL |
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The key parts from G25) ROBOTS on the same ALLIANCE may not blockade the FIELD in an attempt to stop the flow of the MATCH. This rule has no effect on individual ROBOT-ROBOT interaction are "ROBOTS" plural and "no effect on individual ROBOT-ROBOT interaction." |
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Tape... :-D
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Addressing two points in this thread:
1. A "Hammer" or "Tomahawk" is thrown exactly as the name would suggest, over the head. This is not the direction a disc would travel in a flat path. The purpose of this type of throw is to travel at a greater height than distance. This is why human players would use this to throw over the alliance wall. Robots could possibly throw this way. As every new year comes, some team somewhere will make it happen if they try hard enough. 2. The rules state that you may block people at any point as long as they are not touching their pyramid, their safe zone next to the feeder station, and you do not pin them for more than 5 seconds. Although it would be against the spirit of FIRST and stopping the flow of the game, it is legal at this point in the season before any rule updates to block the feeder station. This is something that if seen at a competition, would most likely be changed for the rest of the season. |
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The main reason I see for bothering with a floor pickup system, is for the advantage in autonomous. Last year it was a game decider for some teams that could get extra game pieces to score in autonomous.
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Autonomous would not be the only advantage, but to me it appears to be the main advantage. Thinking of how many game pieces can be scored during a match, it's going to be a challenge for an alliance to use up all 45 in two minutes
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In answer to the original question...
I'd be very tempted to steal an intake from VRC Gateway. Those had to pick up cylinders (though those cylinders were much taller) and the intake design that ultimately emerged was efficient and lightning-fast. Rollers are king. |
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If you can figure out how to pick up 4 discs in ten seconds, then you definitely should be doing that.
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Getting back to the thread title, how does one pick up a disk from the floor?
If we postulate a bot 24" wide, we can put rails near the floor (high enough to clear field imperfections) both fromt and back that funnel the disks to a given spot near robot center. Then, when a disk is detected in the right spot, rollers on both sides pop the disk up a bit. Something captures the disk and sends it off for further processing, maybe a pneumatic cylinder kicks it forward or something. The rollers would be somewhat small diameter so they can catch the edge of the disk, maybe with little fingers of tubing instead of a solid foam/soft surface. |
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Go back and look at 2006, where you were shooting into a vertically oriented goal instead of trying to bank things in off the backboard. That should be a more accurate representation of accuracy, and top robots that year were absolutely deadly (85-90%). Prototyping shooters is absolutely key (if you plan on being a shooting bot). |
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How about if the rollers were inside out duct tape, like a lint roller? Just put on a new "belt" for each match, maybe?
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Personally, I think that picking up frisbees will be a waste of time unless you can do it in under 15 seconds. Given that at the beginning of the match there are VERY few frisbees to be collected, the first minute or so should be a period when you aren't even using your collection mechanism. The last 50 or so seconds, the room starts to populate with frisbees. However, you still have the endgame to play. Plus since each alliance can use 17 frisbees, I doubt teams will be able to make 4 runs back and forth. @ 20 seconds a run, thats 80 seconds, or 1 min and 20 seconds elapsed in tele=op. you still have 40 seconds left. This isn't even taking into account problems like defense and unexpected stuff that just "happens". I think 20 seconds will be a very fast turnaround time near the beginning of the game. 30 seconds left people should definitely start going for the climb.
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To be a great robot you can't just do things well--you also have to do them fast. |
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There is a video this morning showing a shooter that seems to be able to make shots consistently from 50 feet.
So... one strategy might be to park at your feeder and just try to pump in shot after shot. But.... if you miss, having a bot that could pick up from the floor and convert each miss to a score might be a big advantage. And another strategy might be to shoot from the feeder into your end zone, have your teamates pick up and score. Lot quicker than driving around. |
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I wasn't saying their shooter isn't precise, it could be for all I know. Just a word of caution to people trying to infer off the video. They only show a few shots, and with camera cuts. This could be a perfect shooter, it could be a mediocre one.
Teams really need to prototype and prove this for themselves to be truly confidant in their ability to perform. Quote:
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One of my co-workers sent me this. The end of the video is more pertinent than the beginning.
http://www.youtube.com/watch?v=mDlHG...ature=youtu.be |
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Just get something thin and flexible, like bumper cloth, hold it at the top and push out a thin sheet of something that rolls it out. Get under the disk, flip it up like a pancake, and repeat. |
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One of the ideas that our team has tossed around is using some kind of vacume device to create suction in order to pick up the frisbee. We found that it took very little suction to do so. If you are using suction you can pick up the frisbee no matter what side is up. But we havn't discussed how to get the frisbee right side up in order to throw it yet.
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I think people should check out this thera band material, it seems interesting... It might be perfect for frisbees!
http://www.chiefdelphi.com/forums/sh...hreadid=104281 |
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First, does it matter if they are upside down? Just saying you should test this first. Second: Will vacuum still work of the disk is dusty/dirty/scuffed/smooshed a little? |
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I was thinking suction power for a bit... :D however, it takes our 5 horsepower shop vac being 3/8 of an inch away from the frisbee for it to lift it up. (Though once it is lifted, its staying put.) :(
So, considering that a robot definitely isn't going to generate a 5 horsepower vacuum, I think that its out of the question. |
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vacuum cleaners have a rolling brush-like thing that helps suck things up. Although I think that a suction based system would be a bad idea, a rotating brush like thing might help the Frisbees onto a dustbin and keep them there. A vertical conveyor system that was common last year might be modified to lift Frisbees into the shooting mechanism.
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Also, I'm so glad robot in 3 days proved me wrong. It definitely taught me (and our team) to not confuse what a human can do and what a robot can do. Getting back to the original topic though, it just goes to show how good of a game this is (props to the GDC). Time to prototype away! |
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How many balls in 2012 could 1717 pick up on average?
I imagine that this number will be about the same as the best robots that can pick up off the floor. Most teams won't be able to do close to that. For the average team, human player loading is probably better than picking only a few off the ground. |
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My first idea was to find a way to make some kind of directional dry adhesive like the Stanford gecko robot http://nanolab.me.cmu.edu/projects/geckohair/ but although i thing it is possible would take a bit of time. So I started to think of something different that would do the same thing but simpler and sense there has been much talk of plungers/suction cups on chiefdelphi. I thought that a belt lined with many small plungers like the ones found in kids plastic gun toys may be a test worthy approach that may be able to lift a Frisbee from the top. Here is a link to the kind of suction cup i mean http://www.acrylicdesign.co.uk/produ...ms%5Bid%5D=260
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Our team gathered some insight on what would happen during a match. The human player has 40+ disks available to him or her. All that's available for most of the match to the player in terms of dispensing options are slots angled 45 degrees downward. Why should the human player just drop them through the slots onto the ground when they can be dropped into the robot directly? Sure, the frisbees can be thrown during the last 30 seconds of the match, but a person of average human height can only launch it over the wall at a risky angle. When I mean risky, I'm talking about the chance of losing accuracy because the disk will curve extremely (try throwing a frisbee 45 degrees upward into the air).
So the question really is: is picking up disks a) feasibly needed and b) worth the extra resources spent (match time, design time)? We thought otherwise. |
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I'm not sure which video the original comment was referring to but I know my team, 2583, posted a video yesterday showing 3 shots in a row within a foot and there is no editing. The first shot was a few feet off because we did not have our motor up to speed The whole assembly is held together by hand so once it is mounted there will be less variation. I think this proves it is possible to have a very precise shooter http://www.youtube.com/watch?v=fgzBNZLNgLQ |
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Our team has been debating whether to use a shooter, or an arm. we have a prototype shooter but not an arm...Any input?
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I am just going to use my hands to pick up my frisbee I do not know about you guys. On a serious note I think that is a very challenging aspect of this years game.
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We bought a few suction cups at ACE for about $0.50 ea. along with a 3" ABS tube and some screws. It works quite well, actually, we just have to figure out how to get them from the suction cup to the hopper/shooter.
Attachment 13422 |
Re: How to pick up a frisbee
my team had a few ideas for flipping the disks but the one i like the most is a system where the disks actually come into the robot on the side :yikes: and then at the end there would be a little motor with two sticks with gear interactable teeth (don't know what they're called:confused: ) which would push the disk one way or the other based on a distance sensor. Any thoughts?!?
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flipping disks might still be important |
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Well, I've flipped sides on collecting off the floor. I was pretty adamant in an earlier post about off-the-floor collection, but I have to say I agree with Joon now. Collecting will be a definite advantage, and in the final 30 seconds I could see teams scoring a lot from the discs thrown across the floor. Also, teams will probably miss at a higher rate then 85% unless they're "elite". And there's a reason there aren't that many "elite" teams. Picking up, I think, is going to be a very good thing to have. And yes, I everybody permission to make fun of me for flip flopping like this on this issue.
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All good engineers proudly say, "I was wrong" if the data supports it.
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I created a prototype last night to sweep up the frisbee. This was using a 3/8" piece of plywood with about a 1/8" gap under the plywood. The frisbee would pretty consistently pop up onto the ramp.
There are 2 small wheels by the front edge. The idea being that those wheels will keep it from catching on the bump in the carpet. This also had 2 castors on the back edge of the ramp putting it about 4" off the ground. http://www.youtube.com/watch?v=M7JbdU4h6F8 |
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Why would you need to push the discs one way or another? Would you have two shooting mechanisms? |
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All this talk of weather to pick up from the floor or the feeder slots. I dont realy think it is that hard to pick up from the floor and I have devised a realy simple disk flipper that is integral to the conveyor and needs NO SENSOR. So, why not do both. If you are picking up from the floor then you have some kind of hopper. If you have a hopper then it should not be that difficult to collect from the feeder tubes. For that matter, if you can pick up from the floor you can pick up from the floor right in front of the feeder station. Put a sign on the bot for the human player " feed to floor".
I'll post a vid later showing the flipper. Bruce |
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Additional note. Look at the flipper this way. If you lay the disk on the floor the leading edge of the disk is HIGHER if the disk is upside down. Yes, there is your hint.
Bruce |
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If you're trying to get them right-side up on the right hand side: |.\..| |..|.| |./..| ...<< With the open side left, you open the left wall enough to tip it, then open right so it slides down and out. |../.| |.|..| |..\.| ...<< With the open side right, you just open the right wall so it flops out. (May or may not need to kick the left wall inward, depending on bottom slope and exact geometry). As far as floor pickup to vertical robot entry, I'll just leave this here: 2012. |
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Picking up the disks from the field will be a big advantage since there will be a lot of missed shots. That will be especially true in the playoffs where one or two teams are likely to be running back to the feeder zone and shooting. The third robot either plays defense or picks up the disks for some close up shots. I'm very confident the elite teams will be picking up the disks with ease.
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My team is trying to work on the dispute as to whether or not to pick up off the floor. Our only problem to pick up is that our mentors prefer us to pick up from within the bumper frame, since we only have a small amt of space for it, we're no too sure on how to go with it. Any suggestions?
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That would depend entirely on how you're implementing your shooter and to a lesser extent your hopper.
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I was thinking of using a goalie lacrosse stick. Putting it on pneumatics might make it go fast enough for it to scoop up the frisbee.
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The elite teams do everything well; that's why they are elite teams. The question for the rest of us is whether adding a certain feature to our robot will be a good investment or not. If the pickup allows you to acquire disks faster than a trip to the feeder station and it doesn't take too much away from other robot functions (size wise, resource wise, etc.) then it could be a plus. In short, a good floor pickup that doesn't detract from other functionality would be a great thing. I personally don't see it as a must have in this years game. Al G. |
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Is floor pick up necessary? Back in Logomotion, floor pick up was thought to be a necessity. Team 1503 clearly showed everyone wrong. Their robot was hand fed until it was beefy enough to take on Einstein.
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Picking up a frisbee during seeding rounds would be a good idea. Maybe a lot of poor shooters.
During the elimination round there will not be that many disc on the floor to pick up because most of the shooters will be very good. |
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