Go to Post All battery terminals must be wrapped in tape or other insulating material AT ALL TIMES! - Al Skierkiewicz [more]
Home
Go Back   Chief Delphi > Competition > Rules/Strategy
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
Thread Tools Rate Thread Display Modes
  #16   Spotlight this post!  
Unread 10-01-2006, 12:40
wilshire's Avatar
wilshire wilshire is offline
OSNAP. a gear flew out of the robot
no team
Team Role: College Student
 
Join Date: Jan 2005
Rookie Year: 2004
Location: Lafayette, IN
Posts: 162
wilshire is just really nicewilshire is just really nicewilshire is just really nicewilshire is just really nice
Send a message via AIM to wilshire
Re: How will FIRST measure muzzle velocity?

The question is now like last year with seeing how many tetras a team could raise or how much weight it could lift. What speed can you get your Poof balls to go upon exiting the muzzle?
__________________
AIM: wilshire461

Purdue FIRST Teams
Team 461 -http://www.boilerinvasion.org/
Team 1646 - http://www.precisionguessworks.org/
Team 1747 - www.harrisonboilerrobotics.org
  #17   Spotlight this post!  
Unread 10-01-2006, 12:46
Dark Paladin Dark Paladin is offline
Jedi Knight
FRC #1213
Team Role: Leadership
 
Join Date: Jan 2006
Rookie Year: 2003
Location: Beverly Hills, MI
Posts: 5
Dark Paladin is an unknown quantity at this point
Send a message via AIM to Dark Paladin
Re: How will FIRST measure muzzle velocity?

geez how big of wheels and motor r u using to get the ball to go that fast we still are trying to figure it out.
  #18   Spotlight this post!  
Unread 10-01-2006, 13:15
meaubry meaubry is offline
volunteer helper
FRC #6099 (Knights)
Team Role: Mentor
 
Join Date: Jun 2001
Rookie Year: 1997
Location: Shelby Twp, Mi
Posts: 784
meaubry has a reputation beyond reputemeaubry has a reputation beyond reputemeaubry has a reputation beyond reputemeaubry has a reputation beyond reputemeaubry has a reputation beyond reputemeaubry has a reputation beyond reputemeaubry has a reputation beyond reputemeaubry has a reputation beyond reputemeaubry has a reputation beyond reputemeaubry has a reputation beyond reputemeaubry has a reputation beyond repute
Re: How will FIRST measure muzzle velocity?

Who said anything about a motor? There are many other methods available and easy to prototype.
  #19   Spotlight this post!  
Unread 10-01-2006, 13:16
KenWittlief KenWittlief is offline
.
no team
Team Role: Engineer
 
Join Date: Mar 2003
Location: Rochester, NY
Posts: 4,213
KenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond repute
Re: How will FIRST measure muzzle velocity?

Quote:
Originally Posted by Kevin Sevcik
The "best angle" still appears to be near 45 degrees. I've made up a spreadsheet that roughly accounts for air resistance and I'm still getting the best range at around 43 degrees. Definitely not 30 degrees. However, my spreadsheet also doesn't think 35 feet is possible at 30 degrees, so make of that what you will. This is, of course, completely theoretical. We're going to cobble together a prototype in a day or two and see what that says.
wow! did you use a differential equation for the air resistance in the spread sheet? I'm lucky if I can set up Excel to sum a column of numbers and get the right results!

Like most things in the real world projectile motion in air is nonlinear. Even with differential equations the best we can do is approximate it.
  #20   Spotlight this post!  
Unread 10-01-2006, 21:33
DonRotolo's Avatar
DonRotolo DonRotolo is offline
Back to humble
FRC #0832
Team Role: Mentor
 
Join Date: Jan 2005
Rookie Year: 2005
Location: Atlanta GA
Posts: 7,019
DonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond repute
Re: How will FIRST measure muzzle velocity?

Quote:
Originally Posted by KenWittlief
tail wind?

positive spin (floater pitch)?

Human player telekinesis?

spacial disturbance in the time/space continuum?
...robot moving forward at... Gee, the robot speed isn't limited*!! Add a few meters per second to that velocity.

*By rules. Physics is another matter.

Don
__________________

I am N2IRZ - What's your callsign?
  #21   Spotlight this post!  
Unread 10-01-2006, 21:49
Eric Scheuing's Avatar
Eric Scheuing Eric Scheuing is offline
Registered User
FRC #0999 (MechaRAMS)
Team Role: Mentor
 
Join Date: Oct 2004
Rookie Year: 2004
Location: Cheshire, CT
Posts: 415
Eric Scheuing has much to be proud ofEric Scheuing has much to be proud ofEric Scheuing has much to be proud ofEric Scheuing has much to be proud ofEric Scheuing has much to be proud ofEric Scheuing has much to be proud ofEric Scheuing has much to be proud ofEric Scheuing has much to be proud ofEric Scheuing has much to be proud of
Re: How will FIRST measure muzzle velocity?

They will probably know how fast 12 m/s looks. If it looks faster, they would probably be able to know.
__________________




2005-2007: Bobcat Robotics 177
2015-20XX: MechaRAMS 999
  #22   Spotlight this post!  
Unread 10-01-2006, 22:34
Kevin Sevcik's Avatar
Kevin Sevcik Kevin Sevcik is offline
(Insert witty comment here)
FRC #0057 (The Leopards)
Team Role: Mentor
 
Join Date: Jun 2001
Rookie Year: 1998
Location: Houston, Texas
Posts: 3,745
Kevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond repute
Send a message via AIM to Kevin Sevcik Send a message via Yahoo to Kevin Sevcik
Re: How will FIRST measure muzzle velocity?

Quote:
Originally Posted by KenWittlief
wow! did you use a differential equation for the air resistance in the spread sheet? I'm lucky if I can set up Excel to sum a column of numbers and get the right results!

Like most things in the real world projectile motion in air is nonlinear. Even with differential equations the best we can do is approximate it.
Yeah, yeah. It's a terribly grungy approximation. I'm assuming it errs on the short side. It seems like the coefficient of drag could be rather low while the ball was at 12 m/s. At any rate, I don't have enough info on the ball's roughness to figure out what weird curve relating Reynold's Number to Cd I should be using. And I was just too lazy to pull out my numerical analysis book and use something better than a first order approximation.
__________________
The difficult we do today; the impossible we do tomorrow. Miracles by appointment only.

Lone Star Regional Troubleshooter
  #23   Spotlight this post!  
Unread 10-01-2006, 22:54
DonRotolo's Avatar
DonRotolo DonRotolo is offline
Back to humble
FRC #0832
Team Role: Mentor
 
Join Date: Jan 2005
Rookie Year: 2005
Location: Atlanta GA
Posts: 7,019
DonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond repute
Re: How will FIRST measure muzzle velocity?

It seems trivial to me that you could use an optical sensor (like the Allen-Bradley...) and measure how long it takes for the ball to pass. If it is an 18 cm ball (about) and the speed is 1200 cm/sec, then 18/1200 = 0.015 or 15 milliseconds. less than that, it's going too fast.

You should be able to build something like that into a 10" diameter tube perhaps 6" long and just hold it at the end of the launcher, with the launched ball going into a net for safety.

If you want to build one: Note that the A-B sensor has a 1.0 mS 'on' delay and a 1.5 mS 'off' delay, which needs to me measured to see if it is consistent. Also, the RC probably cannot measure time accurately enough. Easiest would be to use an oscilloscope - even a cheap one would be OK.

Have fun. Post photos.

Don
__________________

I am N2IRZ - What's your callsign?
  #24   Spotlight this post!  
Unread 11-01-2006, 00:34
KenWittlief KenWittlief is offline
.
no team
Team Role: Engineer
 
Join Date: Mar 2003
Location: Rochester, NY
Posts: 4,213
KenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond repute
Re: How will FIRST measure muzzle velocity?

sounds like coming up with a device to measure the muzzle velocity of the balls could be an engineering design contest of all its own!
  #25   Spotlight this post!  
Unread 11-01-2006, 00:49
Rickertsen2 Rickertsen2 is offline
Umm Errr...
None #1139 (Chamblee Gear Grinders)
Team Role: Alumni
 
Join Date: Dec 2002
Rookie Year: 2002
Location: ATL
Posts: 1,421
Rickertsen2 has a brilliant futureRickertsen2 has a brilliant futureRickertsen2 has a brilliant futureRickertsen2 has a brilliant futureRickertsen2 has a brilliant futureRickertsen2 has a brilliant futureRickertsen2 has a brilliant futureRickertsen2 has a brilliant futureRickertsen2 has a brilliant futureRickertsen2 has a brilliant futureRickertsen2 has a brilliant future
Send a message via AIM to Rickertsen2 Send a message via Yahoo to Rickertsen2
Re: How will FIRST measure muzzle velocity?

we either just shoot our balls up in the air and measure the distance and use v=sqrt(2gh) or use a photogate borrowed from the physics department. We tried untrasonic probes, but they have a narrow beam angle and are kind of a hassle
__________________
1139 Alumni
  #26   Spotlight this post!  
Unread 11-01-2006, 01:40
TimCraig TimCraig is offline
Registered User
AKA: Tim Craig
no team
 
Join Date: Aug 2004
Rookie Year: 2003
Location: San Jose, CA
Posts: 221
TimCraig is a splendid one to beholdTimCraig is a splendid one to beholdTimCraig is a splendid one to beholdTimCraig is a splendid one to beholdTimCraig is a splendid one to beholdTimCraig is a splendid one to beholdTimCraig is a splendid one to behold
Re: How will FIRST measure muzzle velocity?

Quote:
Originally Posted by ted bell
are they going to have six different radar guns to clock how fast the balls are going?
A problem with radar guns is that they only measure the componen of the velocity that is aligned to the line of sight of the radar gun. If the radar gun is perpendicular to the ball trajectory (the extreme case), the radar gun will see zero velocity. This would make using them for on field measurements problematical IMHO.
  #27   Spotlight this post!  
Unread 11-01-2006, 01:47
Tatsu Tatsu is offline
Audiophile and Physicist.
AKA: Tatsu Hashimoto
FRC #1072 (Harker Robotics Team)
Team Role: Leadership
 
Join Date: Jan 2006
Rookie Year: 2004
Location: Woodside
Posts: 49
Tatsu will become famous soon enough
Send a message via AIM to Tatsu
Re: How will FIRST measure muzzle velocity?

Put two photogates right after your launcher assembly. divide distance by time till trigger.

Done.

But that's not FIRST measureing it, as for them, they'll probably check it the way they check weights.
  #28   Spotlight this post!  
Unread 11-01-2006, 12:32
Henry_Mareck's Avatar
Henry_Mareck Henry_Mareck is offline
Registered User
FRC #0418 (Purple Haze / LASA Robotics)
Team Role: Student
 
Join Date: Oct 2005
Rookie Year: 2005
Location: Austin Texas
Posts: 99
Henry_Mareck is a jewel in the roughHenry_Mareck is a jewel in the roughHenry_Mareck is a jewel in the rough
Send a message via AIM to Henry_Mareck
Re: How will FIRST measure muzzle velocity?

my guess is that during inspection they will ask you to fire a ball at full speed, and measure it there with a radar gun. I have never been to the inspection though, so i dont really know how feasable it would be to test that.
  #29   Spotlight this post!  
Unread 11-01-2006, 12:41
dhitchco's Avatar
dhitchco dhitchco is offline
Awards/Photo/Video "wizard"
AKA: Doug Hitchcock
FRC #1511 (Rolling Thunder)
Team Role: Mentor
 
Join Date: Jan 2005
Rookie Year: 2005
Location: Rochester, NY USA
Posts: 333
dhitchco has a brilliant futuredhitchco has a brilliant futuredhitchco has a brilliant futuredhitchco has a brilliant futuredhitchco has a brilliant futuredhitchco has a brilliant futuredhitchco has a brilliant futuredhitchco has a brilliant futuredhitchco has a brilliant futuredhitchco has a brilliant futuredhitchco has a brilliant future
Re: How will FIRST measure muzzle velocity?

The judge's "weighing" and "size-checking" station is typically located near the pit area. It would be very easy to set-up a 40 foot bullpen firing range in that same space. If your shooting mechanism clears 40', you're way over the maximum muzzle velocity (at a standstill) as in <S02> in section 4.3.1

Now, isn't that easier for the judges than a radar gun? Always think outside the box.....
__________________
The THUNDER just keeps getting LOUDER in 2008....
Team 1511 now supports over 15 FLL teams

RollingThunder....Winner of the 2007 Chairman's Award at Finger Lakes Regional and Spirit Award at Boston.....Winner of 2006 Finger Lakes Regional Engineering Inspriation and Boston Imagery awards.......Winner of 2005 World Championship Rookie All-Star (plus FLR Rookie All-Star, Buckeye Top-Seeded Rookie, GTR Champion, Spirit, and Inspiration)

"Gracious Professionalism is a WAY of life".....
  #30   Spotlight this post!  
Unread 11-01-2006, 12:48
dez250 dez250 is offline
54... What a good number!
no team
 
Join Date: Dec 2002
Rookie Year: 2000
Location: Upstate NY / Manchester, NH
Posts: 1,721
dez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond repute
Send a message via AIM to dez250
Re: How will FIRST measure muzzle velocity?

Quote:
Originally Posted by dhitchco
The judge's "weighing" and "size-checking" station is typically located near the pit area. It would be very easy to set-up a 40 foot bullpen firing range in that same space. If your shooting mechanism clears 40', you're way over the maximum muzzle velocity (at a standstill) as in <S02> in section 4.3.1

Now, isn't that easier for the judges than a radar gun? Always think outside the box.....
Judges, i think you mean inspectors. Also many venues have limited space so having a 40 foot long area to test fire in may be feasible at say 2006 UTC but not so feasible at say Annapolis.
__________________
#5

-Michael Dessingue

Last edited by dez250 : 11-01-2006 at 12:51.
Closed Thread


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Measure Rover Speed Dominator_Legen Electrical 2 25-04-2005 08:05
How to measure low velocity nobtiba Electrical 28 22-04-2005 05:37
How to measure execution time? And code size? gnormhurst Programming 17 17-02-2004 08:06
How do you measure? dez250 General Forum 14 11-01-2004 09:26
Tape measure proboscus tito General Forum 24 29-04-2002 15:56


All times are GMT -5. The time now is 04:54.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi