Go to Post This is where a tenacious NEM comes in very handy. - Mark McLeod [more]
Home
Go Back   Chief Delphi > FIRST > Robot Showcase
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
  #1   Spotlight this post!  
Unread 20-01-2009, 17:53
samboydh's Avatar
samboydh samboydh is offline
Registered User
FRC #0702
 
Join Date: Jan 2008
Location: Culver City, Ca
Posts: 8
samboydh will become famous soon enough
Robot Pre-View

http://www.youtube.com/watch?v=39dXQ...e=channel_page

oh yea look at them wheels.
  #2   Spotlight this post!  
Unread 20-01-2009, 18:03
sdcantrell56's Avatar
sdcantrell56 sdcantrell56 is offline
Registered User
AKA: Sean
FRC #2415 (Wired Cats)
Team Role: Mentor
 
Join Date: Jan 2006
Rookie Year: 2004
Location: Atlanta, GA
Posts: 1,038
sdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond repute
Re: Robot Pre-View

I hope those wheels are a joke. If not then adding wheels does not increase traction. Traction is only influenced by the normal force and the coefficient of friction. Also it looks like the front wheels are unpowered which would decrease your total force you can apply as well. Basically. The amount of wheels doesn't matter this year, and all of the wheels should be powered for the maximum usage of available traction.
__________________

Mentor 2415
  #3   Spotlight this post!  
Unread 20-01-2009, 18:18
guakam0li1089 guakam0li1089 is offline
Registered User
FRC #1089 (Mercury)
Team Role: Communications
 
Join Date: Nov 2008
Rookie Year: 2008
Location: Hightstown
Posts: 32
guakam0li1089 will become famous soon enough
Re: Robot Pre-View

but doesnt having less wheels work better? i think so because with less wheels you are distributing more wieght per wheel making the friction due to gravity greator. (not sure if its right though, just something me and a few other students were disscussing)
__________________
Wise men talk because they have something to say; fools, because they have to say something.
  #4   Spotlight this post!  
Unread 20-01-2009, 18:22
sdcantrell56's Avatar
sdcantrell56 sdcantrell56 is offline
Registered User
AKA: Sean
FRC #2415 (Wired Cats)
Team Role: Mentor
 
Join Date: Jan 2006
Rookie Year: 2004
Location: Atlanta, GA
Posts: 1,038
sdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond repute
Re: Robot Pre-View

Quote:
Originally Posted by guakam0li1089 View Post
but doesnt having less wheels work better? i think so because with less wheels you are distributing more wieght per wheel making the friction due to gravity greator. (not sure if its right though, just something me and a few other students were disscussing)
This is partially right. If all of the wheels are driven then it doesn't matter. Each wheel will have less traction per wheel due to a lower normal force per wheel but the total traction will be the same as the more wheels will add up to the same value. Either way having 16 wheels does not improve traction at all and having unpowered wheels even with 16 wheels means this drivetrain will have less traction than a simple 4wd design.
__________________

Mentor 2415
  #5   Spotlight this post!  
Unread 20-01-2009, 19:01
samboydh's Avatar
samboydh samboydh is offline
Registered User
FRC #0702
 
Join Date: Jan 2008
Location: Culver City, Ca
Posts: 8
samboydh will become famous soon enough
Re: Robot Pre-View

all the wheels are powered. That clip dosnt do justice to how well it preforms.
  #6   Spotlight this post!  
Unread 20-01-2009, 19:05
sdcantrell56's Avatar
sdcantrell56 sdcantrell56 is offline
Registered User
AKA: Sean
FRC #2415 (Wired Cats)
Team Role: Mentor
 
Join Date: Jan 2006
Rookie Year: 2004
Location: Atlanta, GA
Posts: 1,038
sdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond reputesdcantrell56 has a reputation beyond repute
Re: Robot Pre-View

At least all the wheels are powered. You are wasting a large bit of the weight budget with those wheels though.
__________________

Mentor 2415
  #7   Spotlight this post!  
Unread 20-01-2009, 19:51
nathanww nathanww is offline
Hacker
FRC #1678 (Citrus Circuits)
Team Role: Programmer
 
Join Date: Dec 2008
Rookie Year: 2007
Location: Davis, CA
Posts: 224
nathanww is just really nicenathanww is just really nicenathanww is just really nicenathanww is just really nice
Re: Robot Pre-View

Are you using any sort of traction control or steering augmentation? If so, I'm going to have to rethink my plans...
__________________
Get yer robot source code here!
  #8   Spotlight this post!  
Unread 20-01-2009, 20:22
Jonathan Norris Jonathan Norris is offline
Jno
FRC #0610 (Crescent Robotics)
Team Role: Mentor
 
Join Date: Nov 2005
Rookie Year: 2004
Location: Toronto
Posts: 1,082
Jonathan Norris has a reputation beyond reputeJonathan Norris has a reputation beyond reputeJonathan Norris has a reputation beyond reputeJonathan Norris has a reputation beyond reputeJonathan Norris has a reputation beyond reputeJonathan Norris has a reputation beyond reputeJonathan Norris has a reputation beyond reputeJonathan Norris has a reputation beyond reputeJonathan Norris has a reputation beyond reputeJonathan Norris has a reputation beyond reputeJonathan Norris has a reputation beyond repute
Re: Robot Pre-View

I'm sorry to burst your bubble... but more surface area will have next to no effect on the Glasliner surface. Do the math/physics you may want to think about saving all that weight for something else.
__________________
Co-Founder of Taplytics.com
2013 World Champions (1241, 1477, 610)
Crescent Robotics Team 610 Mentor
K-Botics Team 2809 Founding Mentor ('09-'11)
Queen's University Mechanical Engineering, Applied Science '11

Crescent Robotics Team 610 Alumni
  #9   Spotlight this post!  
Unread 21-01-2009, 05:48
RyanCahoon's Avatar
RyanCahoon RyanCahoon is offline
Disassembling my prior presumptions
FRC #0766 (M-A Bears)
Team Role: Engineer
 
Join Date: Dec 2007
Rookie Year: 2007
Location: Mountain View
Posts: 689
RyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond repute
Re: Robot Pre-View

Not at all arguing the physics of friction, but one thing that may change with the extra wheels is how the robot performs while turning. While with this robot, you will certainly not get any more friction when driving in a straight line, distributing the frictional force of the wheels around the robot means that when turning, the amount of torque that each wheel is supplying will be different as its distance to the axis of rotation, for both the linear and transverse friction of the wheels.

While I have not done any actual math, playing with vector diagrams a little yields this:


So it seems that not only are more wheels hurting your weight, they're actually decreasing your ability to turn.
Quote:
Originally Posted by samboydh View Post
all the wheels are powered. That clip dosnt do justice to how well it preforms.
Interesting; have your tried to do comparative testing with only four wheels? Or someone correct me if I'm wrong.

--Ryan
__________________
FRC 2046, 2007-2008, Student member
FRC 1708, 2009-2012, College mentor; 2013-2014, Mentor
FRC 766, 2015-, Mentor
  #10   Spotlight this post!  
Unread 21-01-2009, 06:37
Doug Leppard's Avatar
Doug Leppard Doug Leppard is offline
Registered User
FRC #1902 (Exploding Bacon)
Team Role: Engineer
 
Join Date: Apr 2003
Rookie Year: 2003
Location: Orlando
Posts: 435
Doug Leppard has a reputation beyond reputeDoug Leppard has a reputation beyond reputeDoug Leppard has a reputation beyond reputeDoug Leppard has a reputation beyond reputeDoug Leppard has a reputation beyond reputeDoug Leppard has a reputation beyond reputeDoug Leppard has a reputation beyond reputeDoug Leppard has a reputation beyond reputeDoug Leppard has a reputation beyond reputeDoug Leppard has a reputation beyond reputeDoug Leppard has a reputation beyond repute
Send a message via AIM to Doug Leppard
Re: Robot Pre-View

Some of you missed the point of the video. Watch again and listen carefully to the video. First run is without traction control, second run is with traction control. Notice the obvious difference in traction and acceleration.

This obviously is a proto-type. Any team smart enough to pull off what they did know about wheel configuration.

Good job team 702.
__________________
Doug Leppard
  #11   Spotlight this post!  
Unread 22-01-2009, 14:43
seandherbert seandherbert is offline
Registered User
FRC #0207
 
Join Date: Jan 2009
Location: culver city
Posts: 1
seandherbert is an unknown quantity at this point
Re: Robot Pre-View

http://www.youtube.com/watch?v=fClOU0yYuCA
  #12   Spotlight this post!  
Unread 25-01-2009, 09:38
Wayne Doenges's Avatar
Wayne Doenges Wayne Doenges is offline
We Build Robots......and Careers
AKA: Warthog
FRC #1501 (Team T.H.R.U.S.T.)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 2000
Location: Huntington, Indiana
Posts: 6,326
Wayne Doenges has a reputation beyond reputeWayne Doenges has a reputation beyond reputeWayne Doenges has a reputation beyond reputeWayne Doenges has a reputation beyond reputeWayne Doenges has a reputation beyond reputeWayne Doenges has a reputation beyond reputeWayne Doenges has a reputation beyond reputeWayne Doenges has a reputation beyond reputeWayne Doenges has a reputation beyond reputeWayne Doenges has a reputation beyond reputeWayne Doenges has a reputation beyond repute
Re: Robot Pre-View

Another thing to condsider with multiple wheels. Unless each wheel is EXACTLY the same diameter, only the larger wheels will make contact with the floor. On carpeting this wouldn't make much of a difference, but since we are playing what is essentially a flat floor it should make a difference IMHO.
__________________
We Build Robots and Careers
World's - #1 seeded in Archimedes, WON Archimedes and made it to Einstein
2016 NC District - Guilford County. #13 seeded, Finalist. Won Quality award.
IN District - Tippecanoe. #4 seeded. Won Innovation in Control award.
IN District - Perry Meridian. #3 seeded. Finalist. Won Excellence in Engineering award.
IN District - State Championship. #1 seeded. Finalist. Won Excellence inn Engineering award.



  #13   Spotlight this post!  
Unread 25-01-2009, 12:46
jamie_1930's Avatar
jamie_1930 jamie_1930 is offline
Registered User
FRC #2228 (Cougartech)
Team Role: Student
 
Join Date: Feb 2008
Rookie Year: 2008
Location: Rush-Henrietta
Posts: 371
jamie_1930 is a splendid one to beholdjamie_1930 is a splendid one to beholdjamie_1930 is a splendid one to beholdjamie_1930 is a splendid one to beholdjamie_1930 is a splendid one to beholdjamie_1930 is a splendid one to beholdjamie_1930 is a splendid one to behold
Re: Robot Pre-View

We originally had ideas to utilize multiple wheels to increase traction but after review our physics a little realized that that would just further distribute weight and traction would remain the same.
  #14   Spotlight this post!  
Unread 25-01-2009, 13:20
dtengineering's Avatar
dtengineering dtengineering is offline
Teaching Teachers to Teach Tech
AKA: Jason Brett
no team (British Columbia FRC teams)
Team Role: Mentor
 
Join Date: Jan 2005
Rookie Year: 2004
Location: Vancouver, BC
Posts: 1,833
dtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond reputedtengineering has a reputation beyond repute
Re: Robot Pre-View

As much as I agree with the statement that "in the simplified theory of friction as taught in high school physics class, extra wheels should not increase traction", it is important to remember that the simple relationship between normal force and resultant force makes some assumptions that may or may not hold true in a practical environment.

For instance Formula One race cars evidently find that having a larger contact patch improves traction. This does not contradict the theory taught in high school physics, but does mean that some of the assumptions made in that theory are not valid in the race track environment.

For instance the "high school" theory assumes that neither surface deforms due to the normal force (remember that the regolith lies over top of carpet, and is a fairly thin material...), nor fails under the resultant force. Given the "white powder" produced by spinning wheels as reported on CD, there is definite surface failure during dynamic friction of highly loaded wheels. Perhaps this is less of an issue with lightly loaded wheels....

Perhaps they are on to something with this design, perhaps not. I suspect not, but if the team has tested multiple wheels and found them to be an improvement then they have my congratulations for not being bound by the assumptions of a simplfied theory.
  #15   Spotlight this post!  
Unread 25-01-2009, 15:11
thefro526's Avatar
thefro526 thefro526 is offline
Mentor for Hire.
AKA: Dustin Benedict
no team (EWCP, MAR, FRC 708)
Team Role: Mentor
 
Join Date: Aug 2006
Rookie Year: 2005
Location: New Jersey
Posts: 2,599
thefro526 has a reputation beyond reputethefro526 has a reputation beyond reputethefro526 has a reputation beyond reputethefro526 has a reputation beyond reputethefro526 has a reputation beyond reputethefro526 has a reputation beyond reputethefro526 has a reputation beyond reputethefro526 has a reputation beyond reputethefro526 has a reputation beyond reputethefro526 has a reputation beyond reputethefro526 has a reputation beyond repute
Send a message via AIM to thefro526 Send a message via MSN to thefro526
Re: Robot Pre-View

That's So Awesome.

How many wheels did you have in the back? 8? 10?

In theory more wheels will not increase traction but it will change how your robot handles with the traction thats given. So maybe having that super awesome wheel thing in the back is actually helping them turn with the trailer......
__________________
-Dustin Benedict
2005-2012 - Student & Mentor FRC 816
2012-2014 - Technical Mentor, 2014 Drive Coach FRC 341
Current - Mentor FRC 2729, FRC 708
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
pic: ThunderChickens 2008 Robot View 3 Paul Copioli Robot Showcase 7 21-02-2008 20:58
pic: ThunderChickens 2008 Robot View 1 Paul Copioli Robot Showcase 9 20-02-2008 23:27
pic: ThunderChickens 2008 Robot View 2 Paul Copioli Robot Showcase 2 20-02-2008 16:46
pic: 217 Robot ISO view CD47-Bot Robot Showcase 8 01-03-2004 13:09
pic: ROBOT FRONT VIEW CD47-Bot Robot Showcase 4 25-02-2003 13:34


All times are GMT -5. The time now is 23:57.

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