Doug Traster
17-01-2004, 14:22
I have just read a disturbing thing (I think) in FIRST's Q&A section:
"Q: Is there a seamless transition between the playing field and the ball chute? The kickoff video looks like there was a 1/2 inch steel bar or some structural support there.
A: No. There was an angled piece of 1-1/2" x 1-1/2" aluminum in the opening with the outside of the angle facing up (~1-1/8"). In the final configuration, there will be a vertical piece of 1/4" thick aluminum with the same vertical dimension as before. The ball dynamics are the same in either configuration. Drawings will reflect this change."
My quick energy calculations (with some simplifying assumptions) indicate that if the ball is travelling greater than about 3 ft/sec as it approaches the chute it will bounce up and hit the 16" high top of the chute without going in. Very rough empirical tests seem to confirm this. In practice, it seems to me that the robot must carry the ball all the way to the chute and can't do so very fast at that. To get the ball over the lip moving slowly, the pusher must be closer than 6" from the chute wall. The problem is complicated by the fact that another Q&A says that a rule change in update #3 (not yet available) will prescribe a penalty if the robot breaks the plane of the ball chute. This has major implications for our robot design. Am I overlooking something?
"Q: Is there a seamless transition between the playing field and the ball chute? The kickoff video looks like there was a 1/2 inch steel bar or some structural support there.
A: No. There was an angled piece of 1-1/2" x 1-1/2" aluminum in the opening with the outside of the angle facing up (~1-1/8"). In the final configuration, there will be a vertical piece of 1/4" thick aluminum with the same vertical dimension as before. The ball dynamics are the same in either configuration. Drawings will reflect this change."
My quick energy calculations (with some simplifying assumptions) indicate that if the ball is travelling greater than about 3 ft/sec as it approaches the chute it will bounce up and hit the 16" high top of the chute without going in. Very rough empirical tests seem to confirm this. In practice, it seems to me that the robot must carry the ball all the way to the chute and can't do so very fast at that. To get the ball over the lip moving slowly, the pusher must be closer than 6" from the chute wall. The problem is complicated by the fact that another Q&A says that a rule change in update #3 (not yet available) will prescribe a penalty if the robot breaks the plane of the ball chute. This has major implications for our robot design. Am I overlooking something?