Team Update #2
 

Posted 11 January 2008: http://www.usfirst.org/community/frc...nt.aspx?id=450


What to say about it?

Section 10.2.8.1
The 2008 Trackballs require some care in assembly and inflation. Each Trackball consists of two parts: a Bladder and a Cover. The bladder has a 120cm diameter and is made of 2500g PVC.

Re: Team Update #2
 

Is this as much of a bombshell to everyone else as it is to me? Section 6.3 says the balls are approximately 40", and ours came up a couple inches short even with the help of the compressor. 120cm is more than 47"... I'd think this would make a HUGE difference for a lot of designs, both in terms of the size of your gripper, and how much this thing is going to bounce if you stretch it out 20% more. I'm hoping to see this re-clarified soon.

Re: Team Update #2
 

I like that they clarified that disabled robots may be pushed out of the path of travel without penalty. This was a point of discussion on one of the threads here.

I dislike that they reused <G36>. The OLD <G36> was the height restriction on robots in the opponent's home stretch. Update 1 said <G36> has been removed. Update 2 says <G36> disabled robots may be pushed out of the way w/o penalty. I think that <G36> should have simply been gone, and the new rule should have gotten a new number, rather than reusing the number.

<G38> and <G40> regarding impeding a robot and "bumping to pass" are now only applicable during teleoperated mode. I think this is good, because I think no team would be attempting to implement a "bump to pass" during autonomous. It also opens up some potential defensive strategies which have been discussed elsewhere (i.e. blocking during the hybrid mode).

<G42> now applies the protection of a robot in the process of hurdling to both the robot and the trackball.

The inspection checklist has had "Robot Class" removed -- this was obviously just left in when copying from last year.

<T15> should make qualification matches go a little faster. During elimination matches, the higher seeded alliance can position their robots after the lower seeded alliance positions their robots; during qualification matches, alliances position their robots simultaneously.

Re: Team Update #2
 

The source provided by FIRST for additional trackballs, www.sportogo.com, does not sell 120cm balls, only 102cm (40") balls. I think we just have a typo here.

Also, on that note, I don't see any balls with plain blue or red covers. They're all some sort of hyper-large sports ball and they're all really expensive.

Re: Team Update #2
 

The shells are a special order for FIRST. The bladder can be purchased on its own through Sportogo for $20.50. If you want a second ball completely with shell and bladder, it will be a quite bit more.

Re: Team Update #2
 

Is there a typo in the weight in Team Update #2, too? The update says that the bladder is supposed to be 2500g, whereas the one in your link is only 2200g.

Re: Team Update #2
 

I noticed that after i posted the link. I am going to try to verify that the bladder was not different than this one and repost when i can verify correctly.

Re: Team Update #2
 

Why can't FIRST provide a manufacturer and Part #? This would ensure that everyone gets the proper ball. I did notice last weekend that there was a 40" ball and a 120cm ball mentioned, perhaps you buy the 120cm and only fill it to 40" (i.e., just enough to fill the cover)?

Re: Team Update #2
 

FIRST already ensured that every team received the proper ball, by including one in the kit. :)

Re: Team Update #2
 

I personally like the new <G36> because it doesn't incur a penalty on a robot that has been disabled and cannot move. A penalty would just add insult to injury.

Re: Team Update #2
 

There is absolutely no way that the balls are 47". The cover that came with them would burst at the seams.:ahh: :ahh:

Re: Team Update #2
 

But, doesn't that mean that if a team panics and forgets to push the E-Stop Button they get penalized :confused: :confused:

Re: Team Update #2
 

If it is obvious that there is a problem to the refs, and your team is freaking out, the refs will most likely remind you about the E-stop if at all possible. It may come as a surprise, but refs really don't want to give penalties if they are preventable.;)

Re: Team Update #2
 

Robots can be disabled from the field also. I am sure if it is a safety hazard someone behind the table will pull the plug.

Re: Team Update #2
 

[/notsarcasm]Yeah refs are usually very good at reminding you of these things to prevent penalties.[not sarcasm]
I don't see them having to remind too many teams though. If you tip over and can't go back, the drivers should then know what to do.

Re: Team Update #2
 

On my think, the challenge become bigger! I was afraid to hold a trackball of 40"! So now I'm desperate!!!!rsrs

As higher the task, it will be better!

Good luck to everybody!

Re: Team Update #2
 

OK, so it's likely "102 cm", and not "120 cm". But am I remembering wrong, or wasn't it supposed to weigh 10 pounds? 2500g = 2.5kg = 5.5 pounds. Is the cover 4.5 pounds? :confused:

Re: Team Update #2
 

Be sure to add the weight of air. It seems negligible, but at that size the air could weigh about a pound.

Re: Team Update #2
 

I hadn't thought of that, but I don't think it applies. Archimedes principle, ya' know. Helium would actually subtract weight, for example. We're talking weight, not mass.

Re: Team Update #2
 

I must say I'm very dissapointed in the change to <G40>. Before an effective hybrid mode defense could be played by spacing robots out on the field so as to make it more difficult for opposing robots to navigatge, but opposing robots had a chance of getting through with some really clever programming (or good luck). Now any alliance can effectively limit their opponent to 32 points (3 robots crossing 2 lines and one knocked ball) by simply having all 3 drive forward for a second or two, with the defense only failing if one has enough pushing power to shove a robot a good 10 feet (not likely with many of this year's drivetrains geared for speed).

I wouldn't expect a good hybrid lap bot to get more than 8 points now, I was really looking forward to seeing at least one team pull off well beyond a full lap.

<G36> is a good add though, no sense in making an already disheartened team feel worse with the penalties.

Re: Team Update #2
 

So that would be a 32-0 start for the non-defensive alliance? I think most alliances would be delighted to come out of hybrid mode with a 32 point lead.

I wouldn't worry too much about this rule change affecting the spirit of the game.... all it is doing is simply pointing out that a "bump to pass" rule in hybrid would be very awkward given the challenges that many, many teams have with auto code.

Jason

Re: Team Update #2
 

Remember, it says the bladder is 120 cm. The cover prevents the ball from extending more than 40 in. My panicked team ran out to check how big our ball really was this morning and realized this to be the case.

Re: Team Update #2
 

So are the trackballs going to be 40" or 48" at the competition? My team is on the edge of a herder because of this new information..

Re: Team Update #2
 

They are still 40" The bladders may be able to inflate to 48", but the protecting covering is still only 40"

Re: Team Update #2
 

You have to add the weight of air, And make sure you weigh ur ball if at all possible, because the balls do not all weigh the same ;) ;)

Re: Team Update #2
 

That isn't how much the ball/bladder weighs, it is the weight of the PVC per cubic unit I believe. It's like the insulation in winter gear, 1000 gram thinsulate does not mean there are 1000 grams of thinsulate insulation in it. It is just the weight per cubic unit.

Re: Team Update #2
 

Sportogo says they were the vendor to FIRST for the trackball cover but not the ball.
THe FIRST balls weigh 7.1 to 7.2 lbs. We did this measurement on a really good load cell.

The FIRST cover weighs ~1.5 lbs (weighed by Sportogo on spring scale with 1/10 lb graduations). This would suggest that the FIRST bladder should weigh 5.6 - 5.7 lbs.

The $20.50 Sportogo ball SP01501 weighs 4.4 Lbs (per Portogo) and does not have the "anti burst addative" that makes the PVS have the closed cell foam texture.

The $30 Sportogo Ball SP100001 weighs 4.8 lbs and does have the antiburst addative.

Both of the above bladders at almost 1 lb underweight. We are still on the hunt for the EXACT FIRST bladder.

Note that we did repair the 1.5 inch laceration in our ball by using PVC cement (the stuff for PVC pipes) and a patch made from a deflated 8" PVC ball of similar material (no foam) and clamping overnight. It seems to be holding air. We repaired the tear in the cover using an iron on patch before inflating the patched bladder. Be carefull with the temperature of the iron!