Go to Post Be kind to you mentors. They are exhausted and you need them. - MrJohnston [more]
Home
Go Back   Chief Delphi > Technical > Technical Discussion
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 19-09-2003, 02:51
Soukup's Avatar
Soukup Soukup is offline
Animation Guru
AKA: David Soukup
no team
 
Join Date: May 2002
Location: Grand Valley State
Posts: 303
Soukup is on a distinguished road
caster....no

every how and then I have some imput that is worth while. How I think ill share that.

In this years game we experienced many robots with casters and and center drive. We were thrilled when we got to go against them, and disapoointed when we got paired with them. Why? Caster-bots can turn very quickly and efficiently. And if the game was all about this then it may not be a bad idea. But what you must know is that If I hit your robot anywhere but the front, I will spin you and then push you. You are also going to lose alot of ability to push other teams as well. The more wheels on the ground, the better, this will give you the most resistance to opposing motion.

One team that had a very sweet caster-design was team #9. This team rarely gets the credit they deserved but their robot performed perfectly. They set 4 wheels in the back of their robot (all powered) and had 2 casters in front for balance. They were able to turn effortlessly and were able to resist pushing and pulling quite well.

If you want mobility and power you can always use crab or omni drive (which are a little complicated) but otherwise you could use what we did. We had four wheels on the ground and had a caster attached to a globe motor that could deploy in under a second. As a result we could turn quickly and then pull the caster up for power. We were amazing at defending the stack, and I attribute it to this design, and awesome driving.

hope that helped
__________________
soukupd_gv@hotmail.com

Team 74 Alumni

2003 Great Lakes, Midwest, and West Michigan Regional Animation Award Winner
  #17   Spotlight this post!  
Unread 19-09-2003, 07:35
Greg Perkins's Avatar
Greg Perkins Greg Perkins is offline
7 years, allready!!???!?!?!
AKA: Mongo
no team
Team Role: Alumni
 
Join Date: Feb 2002
Rookie Year: 2000
Location: Nashua, NH
Posts: 1,203
Greg Perkins has a reputation beyond reputeGreg Perkins has a reputation beyond reputeGreg Perkins has a reputation beyond reputeGreg Perkins has a reputation beyond reputeGreg Perkins has a reputation beyond reputeGreg Perkins has a reputation beyond reputeGreg Perkins has a reputation beyond reputeGreg Perkins has a reputation beyond reputeGreg Perkins has a reputation beyond reputeGreg Perkins has a reputation beyond reputeGreg Perkins has a reputation beyond repute
Send a message via AIM to Greg Perkins Send a message via MSN to Greg Perkins Send a message via Yahoo to Greg Perkins
if you would like to use the ability of castors, and get the advantage of being able to have crazy manuverability... try omni-wheels. my team experienced with these last year. what it is if anyone hasnt seen these before, they are a small wheel and they have rollers made into the sides of the wheel, thus acting as a castor. the advantage of these tho, is you can power them, and not be screwed out for manuverability.
__________________
myResume -2004: PARC Referee; Beantown Staff; Battlecry Referee; Summer Frenzy Head Referee; River Rage Head Referee, 2005: Pittsburgh Regional Referee; PARC Referee


XBOX Live Gamertag = TrixAre4Kidss
  #18   Spotlight this post!  
Unread 19-09-2003, 09:10
Chris Hibner's Avatar Unsung FIRST Hero
Chris Hibner Chris Hibner is offline
Eschewing Obfuscation Since 1990
AKA: Lars Kamen's Roadie
FRC #0051 (Wings of Fire (on sabbatical))
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1997
Location: Canton, MI
Posts: 1,489
Chris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond repute
Re: thanks!

Quote:
Originally posted by Mercutio
wow! thanks for all the feedback -- i can't believe you all responded so quickly!

i noticed a lot of people are saying that four-wheel drive is the way to go. how do you do it? we tried four-wheel in FIRST last year, and it was a *disaster*! we couldn't turn at all until we covered the rear wheels with slippery plastic to decrease traction, and even then turning nearly burned out the drill motors. in the end, the only way to get decent manuverability was to run each wheel off a seperate motor. what did we do wrong?

p.s. what does "high centered" mean? i'm afraid i've never heard that term before

again, thanks for all your help!

It is not uncommon for teams to try 4-wheel drive and not be able to turn. I've been working on a 4-wheel drive white paper that shows the calculations you need to make to ensure that your drivetrain will turn. I think it will be done this weekend, so I should be able to post it Monday morning.

"High centered" means that your robot is stuck on something (typically in the center of the robot). The term comes from 4x4 off-roading. Think of it this way: you're driving your Jeep through the woods and you attempt to drive over a large log that is across the path. You get halfway over the log, and your Jeep is now resting with its frame on the log, and your wheels can't get traction. This is because you have something high in the center of your vehicle - hence, your vehicle is "high-centered".

-Chris
  #19   Spotlight this post!  
Unread 19-09-2003, 11:15
Unsung FIRST Hero
Matt Leese Matt Leese is offline
Been-In-FIRST-Too-Long
FRC #1438 (The Aztechs)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1998
Location: Long Beach, CA
Posts: 937
Matt Leese has a reputation beyond reputeMatt Leese has a reputation beyond reputeMatt Leese has a reputation beyond reputeMatt Leese has a reputation beyond reputeMatt Leese has a reputation beyond reputeMatt Leese has a reputation beyond reputeMatt Leese has a reputation beyond reputeMatt Leese has a reputation beyond reputeMatt Leese has a reputation beyond reputeMatt Leese has a reputation beyond reputeMatt Leese has a reputation beyond repute
Send a message via AIM to Matt Leese
I was too lazy to read all the threads so I hope I'm not repeating something but it is very possible to be successful with a center-wheel design. In 1996, team 73 used a center-wheel drive. The center wheels were just powered wheel-chair wheels. There were custom-made spherical casters on the four corners of the robot. The chief advantage of the center-wheel drive at that time was manuverability. This meant that it was possible to spin out of an engagement with another robot. I should also add, that 1996 was the year that 73 was national champions.

Matt
  #20   Spotlight this post!  
Unread 19-09-2003, 22:24
Ryan Foley Ryan Foley is online now
Registered User
FRC #5687 (The Outliers)
Team Role: Mentor
 
Join Date: Jun 2002
Rookie Year: 2001
Location: ME
Posts: 447
Ryan Foley has a reputation beyond reputeRyan Foley has a reputation beyond reputeRyan Foley has a reputation beyond reputeRyan Foley has a reputation beyond reputeRyan Foley has a reputation beyond reputeRyan Foley has a reputation beyond reputeRyan Foley has a reputation beyond reputeRyan Foley has a reputation beyond reputeRyan Foley has a reputation beyond reputeRyan Foley has a reputation beyond reputeRyan Foley has a reputation beyond repute
the main problem with a center drive 2 wheel bot is that when going up a ramp, the casters in front will raise your drive wheels off the ground, getting you stuck. 2 drive wheels in front and casters in the back arent that bad though (omni wheels in the rear are even better)
__________________
Ryan

FRC #5687: The Outliers [2015-?]
FRC #1995: Fatal Error [2007-2009]
FRC #350: Timberlane Robotics [2001-2004]

FRC/FLL volunteer since 2005
  #21   Spotlight this post!  
Unread 20-09-2003, 08:50
generalbrando's Avatar
generalbrando generalbrando is offline
Build, Break, Repeat
AKA: Brandon Mensing
FRC #0246 (Overclocked)
Team Role: College Student
 
Join Date: Nov 2002
Rookie Year: 2001
Location: Boston, MA
Posts: 366
generalbrando is a splendid one to beholdgeneralbrando is a splendid one to beholdgeneralbrando is a splendid one to beholdgeneralbrando is a splendid one to beholdgeneralbrando is a splendid one to beholdgeneralbrando is a splendid one to beholdgeneralbrando is a splendid one to beholdgeneralbrando is a splendid one to behold
Send a message via AIM to generalbrando
My general advice on drive trains:

Don't experiment! I mean, you have to start by experimenting, but once you find something that works (or see it on another robot, hint hint), go for it. Build it, test it, improve it and do it all over again. Team 71 prided theirselves on a special chain ratio with those old drill motors that they didn't change for several seasons until they got these new ones last year (even the walking 2002 model had a classic drive system in the rear). I'm not suggesting necesarily to use a two wheel chain system - but find something that you can build, maintain, and rebuild - that works - and stick with it as long as you can. Another example is Technokats - they have been using a tank tread system forever and even this year when their titanium treads were outlawed - they had a colorful red polymer of some sort in it's place.
__________________
Lead Mentor of Team #246, Boston University Academy and Boston University, Overclocked
www.burobotics.org

  #22   Spotlight this post!  
Unread 20-09-2003, 12:52
golf_cart_john's Avatar
golf_cart_john golf_cart_john is offline
Registered User
AKA: John W
FRC #0095 (Grasshoppers)
Team Role: Coach
 
Join Date: Sep 2003
Rookie Year: 2004
Location: Lebanon, NH
Posts: 38
golf_cart_john is a jewel in the roughgolf_cart_john is a jewel in the roughgolf_cart_john is a jewel in the rough
My team (#95) had a lot of success with a design similar to this. Since casters really mess up steering, we used delrin "scrub wheels" instead. They would slip accross the carpet without trouble while still keeping the robot balanced. Since there were no ramps that year (2002) we didn't get our drive wheels lifted off the ground. We had some trouble getting pushed around, but our strategy was outrunning and outmanuvering, so we didn't need to push very much. The robot ended up being very fast and manuverable. Just don't use casters.
  #23   Spotlight this post!  
Unread 20-09-2003, 13:29
Unsung FIRST Hero
Rich Wong Rich Wong is offline
NYC FIRST Planning Committee Member
no team (NYC FIRST)
Team Role: Mentor
 
Join Date: Jan 2002
Rookie Year: 1999
Location: Brooklyn, NY
Posts: 1,674
Rich Wong has a reputation beyond reputeRich Wong has a reputation beyond reputeRich Wong has a reputation beyond reputeRich Wong has a reputation beyond reputeRich Wong has a reputation beyond reputeRich Wong has a reputation beyond reputeRich Wong has a reputation beyond reputeRich Wong has a reputation beyond reputeRich Wong has a reputation beyond reputeRich Wong has a reputation beyond reputeRich Wong has a reputation beyond repute
Send a message via AIM to Rich Wong
Re: Re: thanks!

Quote:
Originally posted by Chris Hibner
I've been working on a 4-wheel drive white paper that shows the calculations you need to make to ensure that your drivetrain will turn. I think it will be done this weekend, so I should be able to post it Monday morning.

-Chris [/b]
Great, I can't wait to get a copy of the white paper to pass
it along to the NYC teams I work with.

Thanks.
__________________
popularis de ob instinctus agnitionis scientia technologia
Home website: www.nycnjfirst.org
Member of NEMO & e^(i*pi)+1 Fraternity.
Member of Friends of Robots
Member of NYCFIRST Planning Committee
  #24   Spotlight this post!  
Unread 20-09-2003, 14:00
Adam Y.'s Avatar
Adam Y. Adam Y. is offline
Adam Y.
no team (?????)
 
Join Date: Mar 2002
Location: Long Island
Posts: 1,979
Adam Y. is a splendid one to beholdAdam Y. is a splendid one to beholdAdam Y. is a splendid one to beholdAdam Y. is a splendid one to beholdAdam Y. is a splendid one to beholdAdam Y. is a splendid one to beholdAdam Y. is a splendid one to behold
Send a message via AIM to Adam Y.
Quote:
My team (#95) had a lot of success with a design similar to this. Since casters really mess up steering, we used delrin "scrub wheels" instead. They would slip accross the carpet without trouble while still keeping the robot balanced. Since there were no ramps that year (2002) we didn't get our drive wheels lifted off the ground. We had some trouble getting pushed around, but our strategy was outrunning and outmanuvering, so we didn't need to push very much. The robot ended up being very fast and manuverable. Just don't use casters.
Did your team go to the Long Island regional?? I remeber someone doing the same exact thing with their robot.
__________________
If either a public officer or any one else saw a person attempting to cross a bridge which had been ascertained to be unsafe, and there were no time to warn him of his danger, they might seize him and turn him back without any real infringement of his liberty; for liberty consists in doing what one desires, and he does not desire to fall into the river. -Mill
  #25   Spotlight this post!  
Unread 20-09-2003, 16:56
golf_cart_john's Avatar
golf_cart_john golf_cart_john is offline
Registered User
AKA: John W
FRC #0095 (Grasshoppers)
Team Role: Coach
 
Join Date: Sep 2003
Rookie Year: 2004
Location: Lebanon, NH
Posts: 38
golf_cart_john is a jewel in the roughgolf_cart_john is a jewel in the roughgolf_cart_john is a jewel in the rough
Quote:
Did your team go to the Long Island regional?? I remeber someone doing the same exact thing with their robot.
No; we were just at the Manchester (NH) and UTC (MA) regionals. It sounds like it worked for someone else, too.
  #26   Spotlight this post!  
Unread 20-09-2003, 17:03
Madison's Avatar
Madison Madison is offline
Dancing through life...
FRC #0488 (Xbot)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1999
Location: Seattle, WA
Posts: 5,246
Madison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond repute
Quote:
Originally posted by Adam Y.
Did your team go to the Long Island regional?? I remeber someone doing the same exact thing with their robot.
That was Team 263, Sachem High School.

They've had 2-wheeled 'bots for three years running now, but only one (2002) could be considered a "center drive." The rest used teflon or delrin skids.
__________________
--Madison--

...down at the Ozdust!

Like a grand and miraculous spaceship, our planet has sailed through the universe of time. And for a brief moment, we have been among its many passengers.

Last edited by Madison : 20-09-2003 at 18:24.
  #27   Spotlight this post!  
Unread 20-09-2003, 18:22
Rob Colatutto's Avatar
Rob Colatutto Rob Colatutto is offline
Roboticsrob
FTC #10092 (Green.Griffins;)
Team Role: Mentor
 
Join Date: Feb 2002
Rookie Year: 2001
Location: San Diego, CA
Posts: 849
Rob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to behold
Quote:
Originally posted by M. Krass
That was Team 263, Sachem High School.

They've had 2-wheeled 'bots for three years running now, but only one (2002) could be considered a "center drive" the rest used teflon or delrin skids.
Teflon skids, but our 2002 bot also had them. We just had one on each corner and we balanced the weight around the robot so we just rested weight on the side opposite the dirrection we were driving, and then we didn't rest any weight on them when we had 2 goals.
__________________
Follow me on twitter @roboticsrob and my FTC team @griffins10092
  #28   Spotlight this post!  
Unread 02-02-2004, 21:19
scifi3018 scifi3018 is offline
Registered User
#0804
 
Join Date: Feb 2004
Location: rock hill sc
Posts: 20
scifi3018 is an unknown quantity at this point
Lightbulb Re: center-wheel drive

heres what my team used in 2002, it worked great, and we had high manuvarability


.......______
...../---O---\
.../----------\
..|-----------|
.()-----------()
..|-----------|
...\ --------- /
.....\ __O__ /


this is about what the bot looked like, 2 wheels on the sides, and two casters in the front and back, with the globes, it was incredible

Last edited by scifi3018 : 02-02-2004 at 21:23.
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
"Automatic Transmission" Madison Technical Discussion 70 24-11-2003 09:03
Tank Stearing - 4 wheel drive Joe P Technical Discussion 12 04-03-2003 23:05
Full list of teams & competitions archiver 2001 14 24-06-2002 00:52
KSC Results archiver 2000 2 23-06-2002 22:19
wheel drive Greg Needel Technical Discussion 3 29-01-2002 12:12


All times are GMT -5. The time now is 23:04.

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