Chief Delphi - Car Nack Predicts 3/06

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Chief Delphi (http://www.chiefdelphi.com/forums/index.php)

- Car Nack's Corner (http://www.chiefdelphi.com/forums/forumdisplay.php?f=122)

- - Car Nack Predicts 3/06 (http://www.chiefdelphi.com/forums/showthread.php?t=43702)

Kevin Watson

12-02-2006 21:00

Re: Car Nack Predicts 3/06

Quote:

Originally Posted by Billfred

Perhaps the simpler solution is to use a nice and natural part of the planet to our advantage: gravity.

If you can tilt a robot so that it shoots vertically and measure the height from floor to shooter in centimeters, you can have it fire a ball and time how long it's airborne. Throw in some simple math, and bada-bing, you can tell in about ten seconds whether it's legal on the velocity side.

In fact, I'm sure Kevin Watson has been hiding in his workshop doing some black magic with an old RC, some limit switches, and a piece of string cheese to accomplish just that. ;)

You forgot about the flux-capacitor that warps local space-time <grin>.

-Kevin

lil_longo

24-02-2006 23:07

Re: Car Nack Predicts 3/06

i agree but how are they going to check that? are they going to take some radar guns and test the speeds before each match i think its going to take to much work to stop that

Billfred

24-02-2006 23:25

Re: Car Nack Predicts 3/06

Quote:

Originally Posted by lil_longo

i agree but how are they going to check that? are they going to take some radar guns and test the speeds before each match i think its going to take to much work to stop that

From Q&A: http://forums.usfirst.org/showthread.php?t=725

Quote:

Originally Posted by GDC

FIRST is planning to use a two-point infrared speed trap to determine ball exit velocity. These units will be delivered to each competition site.

dubious elise

25-02-2006 00:10

Re: Car Nack Predicts 3/06

Just out of curiosity, couldn't FIRST ask an organization like the USTA or MLB to donate some ball-speed measuring devices? Think about it, in almost every tennis or baseball event you see on tv (and probably a few other sports as well, I just can't think of them offhand) they give the speed that the ball was served or pitched at. If those guns can record speeds up to 150+ mph, they certainly must be able to handle 26.8 mph, right?

And it is a bit of an off-season for both sports, so...

DonRotolo

25-02-2006 22:31

Re: Car Nack Predicts 3/06

Quote:

Originally Posted by Greg Needel

I am personally a fan of the radar gun.

Umm, what about a beam-break sensor? Super simple to build, just as easy to calibrate, portable, battery-powerable, and will work with any shooter.

In case the idea isn't clear: Think of a tube a few inches (maybe a foot) long. Have someone shoot their ball through the tube. In the tube is an emitter (of light) and a sensor (on the sother side of the tube). Simply measure the time that a 7" ball breaks the beam (a few milliseconds) and you have a speed. Of course, the exact size of the ball needs to be measured, and an accurate timer needs to be used.

On the other hand, ask any experienced police officer, they will tell you they can judge the speed of a car to within 2 or 3 miles per hour, just from experience. I'd bet the referees develop a similar feel for speed, and will send teams back to the inspectors often.

Don

Danny Diaz

28-02-2006 17:09

Re: Car Nack Predicts 3/06

Quote:

Originally Posted by Don Rotolo

Umm, what about a beam-break sensor? Super simple to build, just as easy to calibrate, portable, battery-powerable, and will work with any shooter.

You've been reading people's minds/posts, haven't you? :eek:

Vince Wilczynski in this post proposed the very same thing. Vince's setup uses 2 IR sensors (Emitter/Sensor combo, I recognized it as having been shipped in FRC kits sometime in the past 2 years), one at the start of a "tube" and the other at the end, and uses LabVIEW and a USB-DAQ device to measure the speed of the ball traveling through the tube (measures the time between the normally-low digital response from the sensors go "high"). It's not battery powered to my knowledge, but could be. And it's very effective, Vince said his tests worked out fairly well at a "mini-meet" he tried it out at. ;)

-Danny

EricH

28-02-2006 17:14

Re: Car Nack Predicts 3/06

Danny,
The official word is it will be a setup like the one you describe, or something similar. I recall seeing it on CD, in fact, it's referenced higher up in this thread.

Danny Diaz

28-02-2006 17:41

Re: Car Nack Predicts 3/06

Quote:

Originally Posted by EricH

The official word is it will be a setup like the one you describe, or something similar. I recall seeing it on CD, in fact, it's referenced higher up in this thread.

Aha! So it is, I don't know how I missed that gem. It would be nice if NI Pilot Program teams (with the means to do so) would build one of these for people to use for spot-testing at their regional. If anyone wants "general" plans for one of these or the LabVIEW program I'd be happy to help out...

-Danny

Al Skierkiewicz

28-02-2006 21:11

Re: Car Nack Predicts 3/06

I have it on good authority that devices are under construction as we speak and will be shipped to each event.

Bill_Hancoc

28-02-2006 22:19

Re: Car Nack Predicts 3/06

First question...is everybodies shooter shoot the same speed with every different ball in various states or destruction...i know we sure dont

Second question...unless a robot lines up to the edge of the field and delibertly shoots a few balls off into the crowd would the impact of a ball that most likely was lobbed into the crowd be that much of a safety hazard to the normal person (i say this because there may be some special cases where it could be dangerous such as an infant etc.) but how many of these cases do you see in the typical crowd.

just some things to think about

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