All About Ball Control

[BJC]

So after week 1 regionals its pretty clear that ball control is just as or more important then actully kicking (see 910 for great example)...

It is also clear that many teams underestimated the importance of ball control.

Here is a list from the least to most effective ball controlers that I saw this week. (these are on average, there were of course teams that used each of these methods to great effect.)

1. Nothing: I was very suprised by the amount of teams that bothered to build a fully functioning kicker but did not consider a device to hold the ball in place in order to use them effectively. I am sure that these teams will have some sort of device at their next compitition

2. A single roller: This was what most teams had and was also probably the most diverse. The concept behind this being to spin the ball towards the robot fast enough that when backing up or turning the ball would follow, basicly the faster you could spin the ball the more effective you were. Many of the robots with this type of ball control had to move slowly to avoid having the ball roll away although there were several very effective ones that I saw.

3. A vacuum: I did not see very many vacuums this week. However I believe they proformed very well for the teams that choose to use them. The concept being to suck the ball to the robot by maximizing the surface area the vacuum(s) had on the ball, more surface equals more hold on the ball. With this device teams generally had to move up to the ball slowly to aquire it, but then had quite a bit of control over it once it was possessed.

4. A double roller (pincher): I did not see that many double rollers this week either. However, they are in my opinion the most effective of all the devices I have seen yet. The concept being to pinch the ball with one roller on top and a second roller on the bottem reducing the force of the ground against the ball to as close to zero as possible while still maintaining contact. The only problem with this method is that it tends to draw penalties for pulling the ball slightly off the ground especially around the goals and bumps. This means that the slighest bump from another robot may move the ball into an illegal position if this device is not designed exactly right.

What type did your team have?
How effective was it?

Please elaborate!

[pfreivald]

We used a double-roller, but it wasn't at all a pinch. It had two small wheels, the centers of which are slightly lower than the center of the ball, and they are spaced pretty far out. It gives the ball a lot of backspin, which gives us a lot of control.

I'd post a .jpg of the CAD drawing, but I'm at home and it's on my work PC... But I did post it somewhere on one of these threads already.

You can find video of it in action here: http://www.facebook.com/profile.php?...=1212242513708

[Chris is me]

My team originally went with a very 1726 like ball magnet, but we made the mistake of assuming it was trivial to get to work. After ship, we made an impeller with an FP and two suction cups in order to hold the ball. It does moderately well in the shop, we'll see how well it works mounted tomorrow.

If that fails, 80/20 should make for a simple pinch prototype.

[BJC]

Of course, I'm sorry. If anyone has a method that is not one of the four listed Please explain how it works in addition to the other things. Sorry for my short sightedness

In addition:

my team, team 33, is using a single 2" or 2.5" diameter (I can't remember which) roller that has maby a quarter inch of float (able to move up and down) that is covered in roughtop which contacts the ball at the highest point possible without violating the 3" rule.

It was very effective controling the ball while going forward or backward however we probably lose the ball 50% of the time when making a sharp turn.
Overall, however, one of the most effective single rollers I have seen (and I saw a lot because I pit scouted at Kettering)

[pfreivald]

We can strafe and do zero-degree turns with no problems on ours, with no loss of ball control. The only real issue with it is if we get rammed hard... but that wasn't much of an issue, because we generally didn't have a reason to hold on to a ball for more than a second or two.

[dtengineering]

We've got a 2" single roller covered in roughtop on our practice bot, powered by the FP running a 26:1 banebots P60 and contacting the ball at a point about 6.5-6.75" above the ground.

We can slowly back up and turn without losing the ball, but have also found that we need to make sure that we come to a stop slowly if we want to keep control of the ball.

We're going to try changing the gear ratio... to 20:1 and then to 16:1 to see if that works better, as the ball does seem to be spinning a bit too slow at the moment.

I think this was the right year to build a practice bot... we've still got a couple weeks until Seattle to get everything worked out, and then we can bolt it all on when we get there.

Jason

P.S. BJC... I'm pleased to see our approach has been the same as yours. Your team might not remember it, but you were our very first ever alliance partners back in 2004 in Toronto. Your robot was totally awesome that year... although not, unfortunately, awesome enough to compensate for our penalty-inducing rookie ineptness. In any case, I don't think we've played with... or against... you since, but I still hold your team in very high regard.

[DonRotolo]

Our single roller was a shaft, drilled crosswise every inch or so, with loops of latex tubing extending about 2". It was one long piece of tubing, threaded through all the holes, eliminating any problems with holding it in place.

We found that at times the tubing would collapse against the shaft, turning it into just a shaft with a grippy covering (which did not work as well). So, we added 4" long pieces of 1/8" pneumatic tubing through the same holes, these provide the 'keep-it-away" factor enough so that balls couldn't get too close to the shaft.

We use a FP motor and 2/3 of the gearbox, about 600RPM, via a belt that slips (so the FP doesn't stall). Works pretty well, but drive or turn fast enough and it's possible to lose the ball. It is very effective against the wall though.

[Lowfategg]

The best ball control I have seen during week one was team 25's wind tunnel. It was able to hold the ball during all movement and able to grab or recover the ball from a little over 4-6" away.

Rollers seem to be most common and can work well when done properly.

[Alex Cormier]

Originally Posted by Lowfategg

The best ball control I have seen during week one was team 25's wind tunnel. It was able to hold the ball during all movement and able to grab or recover the ball from a little over 4-6" away.

Rollers seem to be most common and can work well when done properly.

Do you have any pictures of this for the people who were not at NJ? This sounds pretty amazing!

[falconmaster]

here is our vacuum ball sucker system. Prototype
http://www.youtube.com/watch?v=Xmmq1_JuQo0

[Austin2046]

here's a pic of the front of our robot showing our ball control mechanism... i don't want to share all of it's secrets... but yes those are rubber bands on the roller. It works pretty well.

http://www.oregonfirst.org/wp/wp-upl...6-DSC_3468.jpg

you can see video of it in action at the Oregon regional here
http://frcstream.com/main.php (click search for events, event name: Autodesk Portland Regional - 2010)

[thefro526]

Originally Posted by Alex Cormier

Do you have any pictures of this for the people who were not at NJ? This sounds pretty amazing!

I don't have any pictures, but I can describe the overall idea pretty well.

There's a Tunnel down the center of the robot that's slightly smaller than the ball. At one end of this tunnel are a series of small fan blades attached to a motor. When the motor is turned on, the fans move such a high volume of air that it creates a suction force that can draw balls in from about a half a foot away.

[NOV8R]

Here's a video showing our competition robot with a lot of footage of our ball control mechanism. As you can see the primary components are rwo FP motors coupled to two Banebot 20:1 gearboxes powering two Banebot 3 7/8 wheels. The mechanism also has a way (ram light) of telling the driver when he is in control of a ball. The driver controls the mechanism via a second stick (left) on the control box. That stick also spins the robot left or right to aim. We have a practice robot with the same mechanism installed. The past few days the driver has been practicing ball control by keeping a person from being able to take the ball away from the robot. The mechanism works very well and we're anxious to see it in action on the playing field. Here's the video http://rambotics.com/video5.html

[Ether]

Originally Posted by NOV8R

Here's the video http://rambotics.com/video5.html

Avast anti-virus reports a Trojan JS Downloader-LQ [Trj] at your link.

Perhaps this is a false positive, but I thought you should know.


~

[pfreivald]

Found it! http://www.chiefdelphi.com/forums/sh...ad.php?t=84014

We ran this with 2/3 of a FP gearbox, and the beauty of it -- besides the fact that it worked really well (see the video linked in my original post in this thread) is that there is no chance of it ever stalling, because it never, ever puts any downward force on the ball (aside from the torque to give it the backspin).

I was truly shocked at how many teams seemed to have considered ball control a sort of add-on, last-minute engineering decision. This is one of the first things we built, and we went through several iterative designs before settling on this one. (Good thing every part of our robot is modular, eh?)