Bouncing TrackBalls

[GBilletdeaux930]

Alright so i havent been able to play w/ the trackballs much since teamwise, we havent blown it up yet, kickoff wise... people were like stealing from ur hands 2 seconds after u got it so yea...

How much do the trackballs bounce? Cause i was thinking...if u hurdled it over the bar...how hard is it to regain control of it if it bounces quite a bit...

[T3_1565]

lets say it won't stay still once it drops 6 1/2 feet lol :D

[popo308]

They are verrrryyyy.... bouncy.

We were punting it 7 feet just to see how far it bounces and it easily bounced back up to 6 feet.

[GBilletdeaux930]

So after the first lap...when probably half the bots have tossed them over...were just going to have bouncing balls everywhere...crushing the less sturdy robots...

I wonder how quickly bots are going to be able to (re)gain control of a ball then...ugh this is going to be exciting...

[Daniel_LaFleur]

Alright so i havent been able to play w/ the trackballs much since teamwise, we havent blown it up yet, kickoff wise... people were like stealing from ur hands 2 seconds after u got it so yea...

How much do the trackballs bounce? Cause i was thinking...if u hurdled it over the bar...how hard is it to regain control of it if it bounces quite a bit...

Dropping the ball from ~6 1/2 feet it bounced ~3 1/2 - 4 feet. In addition, the bounce was not as predictable as we would have liked it to be. I think hurdling will only be 1/2 the problem (and thats a big problem) ... with recovery of the ball being just as difficult, especially if it lands on another robot ;)

[danshaffer]

Unfortunately we dropped the ceiling in our lab (formerly ~30ft) to the point where we can only get the trackball's bottom about 5' off the ground, but our (limited) bounce testing shows that they have a coefficient of restitution (bounciness) of somewhere between 1/2 and 2/3, that is each bounce is about .6 times as high as the previous.
That sounds like a lot of... fun.

[GBilletdeaux930]

So about 4 feet... .6 times as high each bouce... after about 4-5 bounces it might be able to grab IF it doesnt bounce out of the arena... given the only open areas are where the robots are dragged in...

Im to tired to do the math oh how long it would take for it to hit the wall and start bouncing back...parabolas and such...

This might actually give an advantage to robots that are trying to grab and carry them... robots pushing them will have to try and follow it around as it bounces off of walls and robots and such. I dont know that was probably obvious beforehand im just tired... Man only like 2 days in and im already behind on sleep...

[danshaffer]

Well basic kinematics shows that the height of each bounce doesn't matter at all for the time that it will take to hit the wall, just the velocity with which it is released as it is hurdled.
The bouncing height will increase the contact/normal force and thus the friction, but the ball wasn't going to be sliding anyway, presumably it would just start rolling.

[GBilletdeaux930]

ok... so my mind doesnt function well when its tired... lol

so anyways...any ideas on how you would control this or beable to gain control of it while it's bouncin...

[danshaffer]

well you either have to have a solid grabber to take control of it or otherwise just have a big pusher and don't worry about the bounces...

[Jake177]

One easy way to deal with grabbing a moving object is rollers. With a powerful enough mechanism, all you would need to do is touch the ball to grab it. The problem is designing a powerful enough mechanism.

[GMKlenklen]

http://www.youtube.com/watch?v=o4bAuLg7ZmE

[tuzzer]

It doesn't seem too bad. It's not really that hard to catch

[team1203 4life]

[QUOTE=How much do the trackballs bounce? Cause i was thinking...if u hurdled it over the bar...how hard is it to regain control of it if it bounces quite a bit...[/QUOTE]

we just blew our ball up and they are extreamly bouncy just rowling it toward a wall a low speed and it jolted backward

and if you are thinking of regaining controll of it after it was thrown over the hurdel good luck with that because it will be all over the place especialy depending on how good your driver is

[GBilletdeaux930]

Heres an idea...if you used mecanum wheels and an arm...u could chase it down with the wheels easily without having to move your arm from side to side...then once its in front of u try and push it down to speed up the bouncing process w/ the arm...

dunno how easy that would be but its a thought...

[Mike Schreiber]

We dropped hours off the schools stairwell (approx 20 ft) for fun, it easily bounced back 3/4 of the way up, although the ceiling got in the way because there isn't much room to drop things between the stairs and the wall...

[GMKlenklen]

the ball in my video was filled completely by hand... so it's under 10 lbs in weight. I don't know if they'll fill them until they get to 10 lbs, I just went for 40". I *tried* to weigh it using a kitchen scale... i uh... think it was ~7.5 lbs... but it was hard to balance!

[Mrtrom]

The Trackballs bounce a nice distance, but we tested it on a stone floor so that could cause different results, it also depends on how high and fast the track ball is going

[Devon27]

we took ours to the stair well in our school, we dropped it from many different heights (and put carpet down to replicate a field) at and above 6 1/2 feet. 6 1/2 ft. bounced back~3 1/2 ft, 8ft. bounced back~4 1/2 ft, from the top of the stairwell, it hit the ceiling but at least 10-12 ft

[GBilletdeaux930]

So from the numbers that have been given...we can kind of conclude that it bounces about 55% of the way back up when dropped straight down i believe... so i think i can **officialy** conclude that this is going to be...exciting? lol

y'all got any ideas on how to speed up the bouncing process? like at all, even the slightest bit...because at this rate if u dont stop it...its gonna be bouncin off walls like crazy

[Alan Anderson]

We did an informal "bounce test" of a trackball this evening. We tossed it over the overpass and watched it. Well before it would have hit the alliance station wall, it had stopped bouncing enough to be approached safely, and it seemed easily controllable.

[Enigma's puzzle]

Cheif Delphi said it has coefficient of restitution of about .7
my calculations say that after six bounces from original dropping point of 7 ft 8 in center of gravity of the ball over the overpass it will still be bouncing at 10 inches

[Seraph117]

its also not a bad idea in this instance to make your robot armored, like a small tank, just not as heavy, but very compactly built