View Single Post
  #2   Spotlight this post!  
Unread 08-04-2010, 10:00
tim-tim's Avatar
tim-tim tim-tim is offline
Simplicity by Design...
AKA: Tim Miedzinski
FRC #0836 (The RoboBees)
Team Role: Mentor
 
Join Date: Feb 2007
Rookie Year: 2004
Location: Hollywood
Posts: 605
tim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond repute
Re: Ball's Circumference

Quote:
Originally Posted by thefro526 View Post
Has anyone measured any of the balls at competition to see what the actual variance is? They didn't seem to vary too much to me, but then again I can't really eyeball differences in circumference that well.

For design purposes though, I averaged out the Soccer balls to have a 8.75" diameter, which is about a 27.5" Circumference. This worked well for me, as competition soccer balls should vary less than 3/16" +/- from this 8.75" Dimension.
No I didn't measure them, but I can tell you that as the competition went on the balls got "weaker." At the beginning of the day (Match #2) the balls were well inflated (not 9psi by any means probably at 8psi), but by Match #20 they had deflated a considerable amount. From our testing at the shop proved that ball pressure would be such a big factor in its trajectory we had to constantly readjust the kicking strength over the competition. They must have re-inflated them each morning because we saw a jump in performance after not touching it from the previous match the day before.

I think part of the pressure issues comes from rough robot play. However, most of it is probably coming from the seams stretching and an over inflated ball.
__________________
The RoboBees

Tim's Shortcuts Anderson Powerpoles and Crimper, Star/Tube Nuts