The point is that while having the abiltity to find information in a variety of reference sources is a useful skill, it does not replace a good, complete, fundamental knowledge of your subject material. - dlavery [more]
 Chief Delphi Another chapter in the drive train story
 CD-Media CD-Spy
 portal register members calendar search Today's Posts Mark Forums Read FAQ rules

#1
08-15-2002, 01:05 AM
 AdamT . #0401 Join Date: Jan 2002 Rookie Year: 2000 Location: not Blacksburg, Virginia Posts: 836
Another chapter in the drive train story

Now, in all the threads that have been discussed rescently, no one has mentioned a thing about weight distrubution...

So we know how to figure out optimum power and what type of material works well for wheels and treads, but we haven't discussed why these different materials have worked well for certain robots.

The difference that has to be considered is how the weight is distributed among the drive wheels/tread. What was the positioning of the drive train of everyone's robots? How did you go about keeping a low CG and still keep the weight in the optimal position to help the drive train? Was this solved by four wheel drive or by other means?

More preseason thinking.....
__________________

#2
08-15-2002, 01:54 AM
 sanddrag On to my 16th year in FRC FRC #0696 (Circuit Breakers) Team Role: Teacher Join Date: Jul 2002 Rookie Year: 2002 Location: Glendale, CA Posts: 8,390
Our gearbox was at the "rear" of the robot, however the robot can be driven with either end the front. It drove the "rear" axles and sprockets and chains conected the front and rear axles for 4 wheel drive. Everything else on the robot was very semetrical and balanced so to counteract the rear gearbox, the battery was placed more near the front (opposite end). Everything is kept relatively low as our robot is only a total of about 14 inches tall.
__________________
Teacher/Engineer/Machinist - Team 696 Circuit Breakers, 2011 - Present
Mentor/Engineer/Machinist, Team 968 RAWC, 2007-2010
Technical Mentor, Team 696 Circuit Breakers, 2005-2007
Student Mechanical Leader and Driver, Team 696 Circuit Breakers, 2002-2004
#3
08-15-2002, 02:36 AM
 fast frank Registered User FRC #0271 Team Role: Alumni Join Date: Mar 2002 Rookie Year: 2001 Location: Bay Shore, NY Posts: 160
we mounted our battery on the bottom of the robot to help keep a low CG. we also put our air storage tanks down there. plus 5 motors, gears, sprokets, and chains. we had 2 drive wheels in the middle and 4 castors slightly raised at the ends. this kept most of the weight on our drive wheels.
__________________
#4
08-15-2002, 01:57 PM
 Jeff Waegelin El Jefe de 148 AKA: Midwest Refugee FRC #0148 (Robowranglers) Team Role: Engineer Join Date: Aug 2001 Rookie Year: 2001 Location: Greenville, TX Posts: 3,218
Our robot was pretty low to the ground (only 20-some inches tall) and everything but the grabbers sat on the main deck inside. We put the compressor in the front right over the wheel and the battery in the back left over a wheel. The arms went down the middle, but everything else was on a plywood sheet at the mid-wheel level. Our center of gravity was VERY low, unlike last year's bot (which I won't get into.... 13' arms, 26" wheelbase....ugh)...
__________________
Jeff Waegelin
Mechanical Engineer, Innovation First Labs
Lead Engineer, Team 148 - The Robowranglers
#5
08-15-2002, 02:14 PM
 sanddrag On to my 16th year in FRC FRC #0696 (Circuit Breakers) Team Role: Teacher Join Date: Jul 2002 Rookie Year: 2002 Location: Glendale, CA Posts: 8,390
13 foot arms

pictures pictures pictures pictures pictures
__________________
Teacher/Engineer/Machinist - Team 696 Circuit Breakers, 2011 - Present
Mentor/Engineer/Machinist, Team 968 RAWC, 2007-2010
Technical Mentor, Team 696 Circuit Breakers, 2005-2007
Student Mechanical Leader and Driver, Team 696 Circuit Breakers, 2002-2004
#6
08-15-2002, 07:20 PM
 Jeff Waegelin El Jefe de 148 AKA: Midwest Refugee FRC #0148 (Robowranglers) Team Role: Engineer Join Date: Aug 2001 Rookie Year: 2001 Location: Greenville, TX Posts: 3,218
Well, the arms are not quite 13 feet. The robot with arms extended straight up is 13 feet tall. The arms themselves are 8 feet, the robot is 5, 8+5=13. So I cheated a bit....

So, without further adue.... I present Tippy, our stability-challenged, much-cursed 2001 bot:
Attached Thumbnails

__________________
Jeff Waegelin
Mechanical Engineer, Innovation First Labs
Lead Engineer, Team 148 - The Robowranglers
#7
08-15-2002, 11:57 PM
 sanddrag On to my 16th year in FRC FRC #0696 (Circuit Breakers) Team Role: Teacher Join Date: Jul 2002 Rookie Year: 2002 Location: Glendale, CA Posts: 8,390
Thanks for the great picture. I joined the FIRST program for the 2002 season so I hadn't really seen those giant lifting arms before.

I have a question. If you look at the robot in the left of the picture, the wheels are on the outside of the frame. I've seen a few battlebots like this too. Is there any advantage to having the wheels on the outside?
__________________
Teacher/Engineer/Machinist - Team 696 Circuit Breakers, 2011 - Present
Mentor/Engineer/Machinist, Team 968 RAWC, 2007-2010
Technical Mentor, Team 696 Circuit Breakers, 2005-2007
Student Mechanical Leader and Driver, Team 696 Circuit Breakers, 2002-2004
#8
08-16-2002, 12:16 AM
 sanddrag On to my 16th year in FRC FRC #0696 (Circuit Breakers) Team Role: Teacher Join Date: Jul 2002 Rookie Year: 2002 Location: Glendale, CA Posts: 8,390
I forgot to mention a couple things.

First of all, I think all the threads involved with "the drivetrain story" are GRRREAT. Kudos to Patrick Wang for getting us going on something important. I was even inspired enough to go buy a CAD program.

Anyway, what I really posted for is I was wondering how many robots use treads instead of wheels? Does it give that much more traction? I would personally use them for the coolness factor alone but the pulleys are between \$80 and \$120 apiece!!! How hard would it be to make our own. Could it be done on manual mills/lathes or would we need CNC.
__________________
Teacher/Engineer/Machinist - Team 696 Circuit Breakers, 2011 - Present
Mentor/Engineer/Machinist, Team 968 RAWC, 2007-2010
Technical Mentor, Team 696 Circuit Breakers, 2005-2007
Student Mechanical Leader and Driver, Team 696 Circuit Breakers, 2002-2004
#9
08-16-2002, 03:42 PM
 kevinw Registered User #0065 Join Date: May 2001 Location: Farmington Hills Posts: 132
Quote:
 Originally posted by sanddrag Thanks for the great picture. I joined the FIRST program for the 2002 season so I hadn't really seen those giant lifting arms before. I have a question. If you look at the robot in the left of the picture, the wheels are on the outside of the frame. I've seen a few battlebots like this too. Is there any advantage to having the wheels on the outside?
As the Pontiac commercial people will tell you, Wider is Better. To see the effect on stability, take it to an extreme, and imagine placing the wheels very close to each other in the middle, or on the very far edges far apart from each other.
#10
08-18-2002, 11:35 AM
 Jack FIRST Scouting Network AKA: Andrew Schenk FRC #0201 (The FEDS) Team Role: Alumni Join Date: Feb 2002 Rookie Year: 2002 Location: Rochester Hills Posts: 651
Our robot this year could pull a lot. (don't remember how much though) We had 4 wheels with this kind of elevator belt that has a lot of grip. Personally, tracks weigh more and are harder and more \$\$ to make. But if you can have the weight, \$\$, and time then sure, use tracks.

PS i included a pic of our fancy wheels w/ the tread.
Attached Thumbnails

__________________
Team 201 - 2003 Great Lakes Semifinalists & 2003 Archimedes Division Finalists :|: Webmaster of www.feds201.com -> FBI Scouting
Winner of The 2003 ChiefDelphi Web Award for: User That Started The Most Non Chit Chat Threads
Winner of: 2003 FIRST Ventures with 5451.68 End Points

**Check out the New FIRST Scouting Network**
#11
08-19-2002, 08:58 AM
 ChrisH Generally Useless FRC #0330 (Beach 'Bots) Team Role: Engineer Join Date: Jun 2001 Rookie Year: 1998 Location: Hermosa Beach, CA Posts: 1,229
Quote:
 Originally posted by sanddrag I forgot to mention a couple things. First of all, I think all the threads involved with "the drivetrain story" are GRRREAT. Kudos to Patrick Wang for getting us going on something important. I was even inspired enough to go buy a CAD program. Anyway, what I really posted for is I was wondering how many robots use treads instead of wheels? Does it give that much more traction? I would personally use them for the coolness factor alone but the pulleys are between \$80 and \$120 apiece!!! How hard would it be to make our own. Could it be done on manual mills/lathes or would we need CNC.
What CAD program did you get? Also, while an NC machine isn't required to do belt pulleys, it would save time and effort. You could use a thing called a dividing head on a manual mill. It could also be used to make gears.
__________________
Christopher H Husmann, PE

"Who is John Galt?"
#12
08-19-2002, 01:13 PM
 sanddrag On to my 16th year in FRC FRC #0696 (Circuit Breakers) Team Role: Teacher Join Date: Jul 2002 Rookie Year: 2002 Location: Glendale, CA Posts: 8,390
The CAD program I bought is made by Swift software and is called 3D CAD. It was \$2.88 on the clearance table at Office Depot. The program is worth nothing for scale drawings or precise measurements but it works excellently for laying things out for initial concepts. It is also very useful for showing other people your ideas. For \$3, it can't be beat.
__________________
Teacher/Engineer/Machinist - Team 696 Circuit Breakers, 2011 - Present
Mentor/Engineer/Machinist, Team 968 RAWC, 2007-2010
Technical Mentor, Team 696 Circuit Breakers, 2005-2007
Student Mechanical Leader and Driver, Team 696 Circuit Breakers, 2002-2004
#13
09-04-2002, 03:57 PM
 Greg Perkins 7 years, allready!!???!?!?! AKA: Mongo no team Team Role: Alumni Join Date: Feb 2002 Rookie Year: 2000 Location: Nashua, NH Posts: 1,203
most of our bots from the last couple of years were EXTREMELY LOW to the ground!! 2001 we had 3inches of ground clearence, this year we had 3/8ths of an inche!!! we use wheels that we make ourselfs, chassis are low to the ground and not alot about the cg.

pics:
Attached Thumbnails

__________________
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
#14
09-16-2002, 07:24 PM
 dets002 Registered User #0811 (Cardinals) Join Date: Jan 2002 Location: Nashua, NH Posts: 21
Our robot had an intriguing design. To ease zero radius turns, we had only two drive-wheels mounted in the center of the robot and had castors on the front and back. Most of the weigh was centered low around the chasis plate and the battery was the lowest point on our robot (beside the wheels) which lowered the center of gravity substantially. The wheels were powered by two drill motors and a 200:1 gear / chain reduction. Thus, to keep the weight on the wheels, we just balanced the wheels. However, I do suspect that if we had used more drive wheels, we could have gotten more traction, which always helps, but we wanted to tread lightly on the carpet.
__________________
Snow Mountain Ranch, Granby, CO
#15
09-17-2002, 02:18 PM
 Jeff Waegelin El Jefe de 148 AKA: Midwest Refugee FRC #0148 (Robowranglers) Team Role: Engineer Join Date: Aug 2001 Rookie Year: 2001 Location: Greenville, TX Posts: 3,218
We've used the two-wheel drive with castors setup before. It's worked pretty well for us. It turns well, and can push okay, but sometimes you just need the power and traction 4-wheel-drive offers. Plus, if there is any kind of incline, that setup won't work. You'll high-center your 'bot when you try to go up the ramp. It's not perfect, but it's surely simple and effective.
__________________
Jeff Waegelin
Mechanical Engineer, Innovation First Labs
Lead Engineer, Team 148 - The Robowranglers

 Thread Tools Display Modes Rate This Thread Linear Mode Rate This Thread: 5 : Excellent 4 : Good 3 : Average 2 : Bad 1 : Terrible

 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 User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Announcements     User Announcements FIRST     General Forum         FIRST E-Mail Blast Archive     Rumor Mill     Career     Robot Showcase Technical     Technical Discussion     Robotics Education and Curriculum     Motors     Electrical         CAN     Programming         NI LabVIEW         C/C++         Java         Python     Control System         FRC Control System         Sensors     Pneumatics     Kit & Additional Hardware     CAD         Inventor         SolidWorks         Pro ENGINEER / Creo     IT / Communications         3D Animation and Competition         Website Design/Showcase         Videography and Photography         Computer Graphics     National Instruments LabVIEW and Data Acquisition         LabView and Data Acquisition Competition     Awards         Chairman's Award     Rules/Strategy         Scouting         You Make The Call     Team Organization         Fundraising         Starting New Teams         Finding A Team         College Teams     Championship Event     Regional Competitions     District Events     Off-Season Events     Thanks and/or Congrats     FRC Game Design     OCCRA         OCCRA Q&A         OCCRA Programming Other     Unsung FIRST Heroes     Chit-Chat         Games/Trivia             Fantasy FIRST     Car Nack's Corner     College & University Education     Dean Kamen's Inventions     FIRST-related Organizations         Western Region Robotics Forum         Robot Chicks Union (RCU)         Southern California Regional Robotics Forum         FIRST Interactive Rural SupporT         FIRST Scouting Network         FloridaFIRST         FIRSTwiki         The Blue Alliance             Video Archives     FIRST Historians     FIRST In the News...     FIRST Lego League         Lego Mindstorm Discussion     FIRST Tech Challenge     VEX         VEX Robotics Competition         VEX IQ     Televised Robotics     Math and Science         NASA Discussion ChiefDelphi.com Website     CD Forum Support     Extra Discussion Old Forum Archives     1999     2000     2001

 Similar Threads Thread Thread Starter Forum Replies Last Post White Paper Discuss: Drive Train Basics CD47-Bot Extra Discussion 6 09-06-2012 10:42 AM pic: Next Years Drive Train CD47-Bot Extra Discussion 15 06-11-2003 08:32 PM Image Discuss: Transmissions and Drive Train CD47-Bot Extra Discussion 16 02-17-2003 09:11 PM what's your most important drive train advice? Ken Leung Technical Discussion 42 01-07-2003 08:58 AM Blowing fuses/tuning drive train DougHogg Motors 10 06-22-2002 11:24 PM

All times are GMT -5. The time now is 04:24 PM.

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

 -- English (12 hour) -- English (24 hour) Contact Us - Chief Delphi - Rules - Archive - Top