View Full Version : Mechanism to Possess Soccer Balls
timpanda
14-01-2010, 22:02
Does anyone have a good idea or tips for an effective way to pull in a soccer ball, maintain possession of it by continually holding it, while still being able to drive forwards, reverse, and turn? So far the only idea that comes to mind is a vacuum. Your thoughts? Thanks. :)
Dave McLaughlin
14-01-2010, 22:08
Might want to check out the Ball Magnet (http://www.chiefdelphi.com/forums/showthread.php?threadid=80203) thread...
timpanda
14-01-2010, 23:12
Oh, thanks. I guess my thread was a waste then
Dave McLaughlin
14-01-2010, 23:23
As long as you got the help you were looking for, then it was not a waste at all. :)
timpanda
14-01-2010, 23:34
I watched the ball magnet video and it seems like there's a cylindrical wheel thats spinning in the direction of the robot to pull in the ball and the wood is only there so it does not go into the robot, like the balls would have for last years game. But i think there's a way i could implement this somehow and possibly also use a vacuum to help maintain possession. So this was a big help :D
MrForbes
14-01-2010, 23:37
Try it with the roller and you might decide you don't need vacuum. But you'll have to try it to know, won't you?
timpanda
14-01-2010, 23:41
good point, i'll try to put something together tomorrow to test it out.
The limiting factor with our robots is the three inch rule. In our test the ball stayed with the robot going left and going right and even backwards but when the robot moved forward and suddenly stopped the ball popped right out.
Unless we can overcome this limitation the magnet may not work as well as we hope. The next step for us will be trying different sticky materials to coat the roller with . Any good suggestions?
Yeah, I was planning on trying out a vacuum suction deal, but after seeing the power of the roller, I think that is all we will need. Looks like tomorrow I'll be trying out the roller on last year's bot wit the soccer balls. Too bad we just pulled the cRio out!
timpanda
14-01-2010, 23:51
maybe have something thats gonna have a lot of friction with the ball like sandpaper so that even if you stop it won't move away from the bot, cause the material will be too rough.
MrForbes
15-01-2010, 00:00
It will be interesting to see how changing the height of the roller and ingress of the ball affects it. I can see how it could be a problem if we have the ball not in so far, so we'll work on prototyping a more legal version real soon.
Thanks for the input Sam.
btw the roller in ours is ABS pipe covered with spray rubber, which is a product designed for coating tool handles and such.
Coach Norm
15-01-2010, 00:11
Unless we can overcome this limitation the magnet may not work as well as we hope. The next step for us will be trying different sticky materials to coat the roller with . Any good suggestions?
How about the Sticky Pad? It is a tacky material to help hold cell phones, PDAs, etc. on a dash.
Another idea is the tacky shelf liner. It come in large rolls, so you should be able to attach it to a roller.
Good luck. I look forward to seeing your results.
I was thinking of using spray rubber.
We have lots of experience with drawer liner, but it just falls apart to easily. Not a big problem last year but not real good for the soccer balls. The other thing to worry about is the inflated state and the surface texture of the ball can cause problems.
I'm thinking about a spring loaded roller or something.
David Brinza
15-01-2010, 03:06
btw the roller in ours is ABS pipe covered with spray rubber, which is a product designed for coating tool handles and such.
We used the same coating on our grippers to handle game pieces in 2007. Tackiness rules!
RC Dawson
15-01-2010, 10:45
Imagine a large pair of pliers. Take the handles, coated with friction tape or gripper tape, and point them away from you. With the handles opened as wide as they go, the mechanism could satisfy the perimeter rules. Considering the 3 inch penetration rule, when you get to a soccer ball and close the plier-inspired device, the "handles" may in fact extend up to the bumper perimeter, but two seconds may be enough time to grab the ball, reposition, and pass it up field.
Thoughts?
timpanda
15-01-2010, 16:53
so i tried out the shop vac idea today and it had very little suction to do anything. We're definitely considering the roller idea with either that spray on rubber, that tacky material, or the sticky pads. I don't know yet we have to test it out and look at the results. I'm going to try and design a prototype on inventor and test the limits of the three inch rule while still being able to keep possession of the ball.
timpanda
15-01-2010, 23:35
Imagine a large pair of pliers. Take the handles, coated with friction tape or gripper tape, and point them away from you. With the handles opened as wide as they go, the mechanism could satisfy the perimeter rules. Considering the 3 inch penetration rule, when you get to a soccer ball and close the plier-inspired device, the "handles" may in fact extend up to the bumper perimeter, but two seconds may be enough time to grab the ball, reposition, and pass it up field.
Thoughts?
I think your idea could work, but i'm not sure how well of control you'll be able to have. But is two seconds really enough, you can't really do that much with such little time and have to react very quickly and efficiently to prevent getting a penalty. Do you think its possible for you to close the plier-inspired device and still satisfy the 3 inch rule. We're planning on over compensating the design so that it is physically impossible to break this rule. But still sounds like an interesting idea. Let me know how the friction with the soccer ball is after you try out your idea, cause the ball slipping is going to be an issue if you're trying to maintain control and possession.
billfunk29
16-01-2010, 21:48
Any ideas on a two stage vacuum system. High volume until the ball catches and then a high pressure to hold it. Moving a high volume of air for any lenght of time will take a toll on the batteries.
trilogy2826
16-01-2010, 23:40
We successfully finished our prototype of our intake roller design and it is a marvelous thing to watch. Not being immodest, I am just amazed it works as well as it does. We literally had a student skid a ball toward our roller as fast as he could and it stuck with virtually no noticable elastic collision.
We went with a 1 inch PVC pipe coated on both Brecco-flex and tool-handle-rubberized-coating and both worked equally well. Since the coating is significantly less weight, we are definitely going that route.
We also tested our scissor/plier handle idea as was mentioned in the thread earlier and it works extremely well, but the final mechanism we would have to design gets a little complex when trying to also avoid conflicts with a kicking mechanism.
We finally came up with a concept that can grab the ball on any place of the roller, bring it to the center, and hold the ball "perfectly" in the center of the robot even when turning. It can be done and maybe we will give up a few hints in an upcoming video post.
BTW: I thought the task of gaining control of a ball and actually moving it around the field like the play thing it is was near impossible in 3" until we finished today. Keep trying a bunch of different things and you'll eventually get it.
MrForbes
16-01-2010, 23:43
Thanks for the report!
Scott358
16-01-2010, 23:48
Yes, thanks for the report!
Quick question.... was this test done on carpet?
trilogy2826
17-01-2010, 04:46
Absolutely. It was done on carpet. Thanks for catching my omission.
DonRotolo
17-01-2010, 08:42
maybe have something thats gonna have a lot of friction with the ball like sandpaper so that even if you stop it won't move away from the bot, cause the material will be too rough.
Just be careful of<G26> ARENA Damage - ROBOTS may not damage any part of the ARENA or BALLS. For
ROBOTS that violate this rule, the TEAM may be required to take corrective action (such as
eliminating sharp edges, removing the damaging MECHANISM, and/or re-inspection) before
the ROBOT will be allowed to compete in subsequent MATCHES.
Tackiness rules!You mean like Dave's Loud Hawaiian Shirts tackiness??:rolleyes:
Lavapicker
18-01-2010, 20:19
we've been trying similar things with rollers on carpet but the balls grip and go under. With new soccer balls they tend to grip the carpet when pushed down on and so don't spin well. On smooth floor or on older balls it works perfectly. Any suggestions?
Ivan Helmrich
18-01-2010, 21:09
I'm having similar problems with the ball not sliding on the carpet and wanting to pull under the roller. I tried some small rollers behind the ball, below the center line with some success, but the positioning is really touchy. The slight out-of-round of the ball is enough to stop the spinning. Next, I think I'll try letting the roller move up and down and see if that helps.
Gearheads1
18-01-2010, 23:16
The friction and speed of the roller seem to make a big difference, and slower may be better. The roller doesn't have to be real large either.
Vikesrock
18-01-2010, 23:24
I'm having similar problems with the ball not sliding on the carpet and wanting to pull under the roller. I tried some small rollers behind the ball, below the center line with some success, but the positioning is really touchy. The slight out-of-round of the ball is enough to stop the spinning. Next, I think I'll try letting the roller move up and down and see if that helps.
In our testing we found that a roller coating that could not easily compress helped reduce the tendency of the ball to want to pull under the roller.
I'll try to get our video of a prototype using drawer liner material on a PVC roller up somewhere to post here. The carpet we were able to scrounge up on short notice was berber and very different from the competition carpet, but we still found the test successful enough to move forward with the idea.
EDIT: Here's the video (http://vimeo.com/8834046)
Ivan Helmrich
19-01-2010, 13:59
Kevin, thanks for the video. I think the big difference is that I had my roller mounted higher up on the ball. I'll try lowering it an see what happens. Otherwise, my setup looks pretty similar. The ball I was using doesn't have a shiny surface so it may grip the carpet more. I'll try another ball too.
MrForbes
19-01-2010, 14:01
We got one of the spec balls, not the right color, but it is a HS300 it's very glossy.
Ivan Helmrich
19-01-2010, 21:43
I just tried a glossy ball, not the spec ball, and probably not quite as glossy but not matte either. Much better. I should have read the "out of stock" thread first. The height of the roller is much less touchy with the slick ball too. Maybe this will be the one advantage of being at a first-week regional, the balls won't be scuffed up yet.
Slow is definitely better, we tried last-years robot with a piece of plywood at three inches from the roller, and it kept it in perfectly. We then tried our shooter from 2006 just as a test, and well the ball has a nice 1/8" deep grind mark in it from the shooter :p
MrForbes
19-01-2010, 23:13
Soccer balls do NOT compress like Orbit balls! We're looking at designing a pivoting support for the roller to keep relatively constant pressure on the ball.
Tytus Gerrish
20-01-2010, 21:04
vacuum may work too good
Video of suction mechanism (http://www.youtube.com/watch?v=sxDGLgaA3QY)
timpanda
22-01-2010, 13:04
our roller works pretty well, and right now we're testing different types of roller material, to test the best friction force. How do you think i could make the roller that had a spring on the two sides so the roller would compress up and capture the ball better and when the ball wasn't underneath it, it would release the tension in the spring and it would go back down to its original position?
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