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-   -   pic: Team 195 driving base 2007 (http://www.chiefdelphi.com/forums/showthread.php?t=54179)

jjdebner 15-02-2007 03:24

pic: Team 195 driving base 2007
 

Gabe 15-02-2007 03:27

Re: pic: Team 195 driving base 2007
 
WOW!!!:D :D :D Engine turned finish, full welded frame, anodized custom wheels, custom shifting transmissions...

Can I get a close up of those wheels? :)


(P.S. Please post more pictures!)

Jeffrafa 15-02-2007 03:47

Re: pic: Team 195 driving base 2007
 
:ahh: Are those transmission plates delrin???

If so, that seems to have become a popular choice this year - Suddenly I feel left out with my plain old custom aluminum transmission plates ...

BTW - those wheels really came out nice with some anodizing! I'm still anxiously awaiting what ours will look like (they are going in tomorrow, hopefully)

- Jeff

Rosiebotboss 15-02-2007 07:34

Re: pic: Team 195 driving base 2007
 
What, no tank treads??

Billfred 15-02-2007 08:58

Re: pic: Team 195 driving base 2007
 
This plain looks awesome. Seems sort of reminiscent of West Coast Drive, with some requisite east-coast tweaks.

But what I'm really loving is how the CIMs are mounted on the transmissions. We're running the AndyMark two-speeds this season, and fitting them in with everything else has been a little hard at times. (Don't get me wrong, I still think we made the right choice for our situation--it's all part of the challenge.) Should the time come for us to start rolling our own transmissions, this is a picture I'm coming back to.

Hope to see this one in Atlanta!

techtiger1 15-02-2007 10:32

Re: pic: Team 195 driving base 2007
 
Kudos on the custom wheels and delrin plates very nice. West coast style drive is always a winner I like the modifications to it though you guys have made. 1251 has a similiar drive base this year. Ohh ya the finish on that box tube is sweet,neat touch. Looks like a battle ready base see you guys in Atlanta hopefully.

Mike Norton 15-02-2007 11:23

Re: pic: Team 195 driving base 2007
 
Quote:

What, no tank treads??

I think they are also taken on a new look this year. Nice rims I like the blue

jjdebner 15-02-2007 11:42

Re: pic: Team 195 driving base 2007
 
believe it or not the delrin is only in the temp chain tensioners...
all the black is simply ABS plastic

P.S.
the swirl finish looks really pretty black ;-)

Tom Bottiglieri 15-02-2007 11:52

Re: pic: Team 195 driving base 2007
 
Quote:

Originally Posted by jjdebner (Post 578742)
all the black is simply ABS plastic

Meh, I never did like the efficiency of those crash shifters.

Either way, you guys are gonna rock this year. This base looks good, and a practice bot/full playing field doesnt hurt!

(Any other college mentors feel like they got the short end of the stick when they left?)

waiakea11 15-02-2007 12:41

Re: pic: Team 195 driving base 2007
 
wow 6 wheels? how do you turn?

Brandon Holley 15-02-2007 14:58

Re: pic: Team 195 driving base 2007
 
cant wait to see this at the scrimmage !!!



tom...you were holding them back...hahaha jk guys

Nuttyman54 15-02-2007 15:03

Re: pic: Team 195 driving base 2007
 
Quote:

Originally Posted by waiakea11 (Post 578778)
wow 6 wheels? how do you turn?

You lower the middle wheel by a small amount (usually 1/8" to 1/4") so that at any given time your wheelbase is small for easy turning, but you have the stability of a longer wheelbase. Only 4 wheels can contact the ground at any given time (unless you have VERY soft carpet)

Heretic121 15-02-2007 19:02

Re: pic: Team 195 driving base 2007
 
Quote:

Originally Posted by Tom Bottiglieri (Post 578747)
(Any other college mentors feel like they got the short end of the stick when they left?)

Yes and thats why i came back =P...

looks great guys cant wait to see you at UTC *ill be scouting all of you for nats!!!*

nuggetsyl 15-02-2007 19:12

Re: pic: Team 195 driving base 2007
 
Quote:

Originally Posted by Nuttyman54 (Post 578856)
You lower the middle wheel by a small amount (usually 1/8" to 1/4") so that at any given time your wheelbase is small for easy turning, but you have the stability of a longer wheelbase. Only 4 wheels can contact the ground at any given time (unless you have VERY soft carpet)

Y lower the middle wheel. Makes no sence. :confused:

Nuttyman54 15-02-2007 19:31

Re: pic: Team 195 driving base 2007
 
Quote:

Originally Posted by nuggetsyl (Post 579026)
Y lower the middle wheel. Makes no sence. :confused:

With any 4 wheel tank-drive wheelbase, long and narrow is much better at going straight, short and wide is better for turning. The problem with the short and wide is that it's easy to tip over in the forward and backwards because of the short wheelbase. The remedy is to take your long and narrow base and put a middle set of wheels that is lower than the rest. This gives you essentially two sets of "short n' wide" wheelbases that you rock between. This makes you hard to tip, but also makes it much more efficient to turn, and gets rid of the characteristic "hop" that many high-traction, 4wd robots have.

another version of the 6wd solution is to keep all the wheels on the same level and replace one or both of the outboard sets with omnis (see 488's robot this year)

nuggetsyl 15-02-2007 19:35

Re: pic: Team 195 driving base 2007
 
Quote:

Originally Posted by Nuttyman54 (Post 579050)
With any 4 wheel tank-drive wheelbase, long and narrow is much better at going straight, short and wide is better for turning. The problem with the short and wide is that it's easy to tip over in the forward and backwards because of the short wheelbase. The remedy is to put a middle set of wheels that is lower than the rest. This gives you essentially two sets of "short n' wide" wheelbases that you rock between. This makes you hard to tip, but also makes it much more efficient to turn, and gets rid of the characteristic "hop" that many high-traction, 4wd robots have.

another version of the 6wd solution is to keep all the wheels on the same level and replace one or both of the outboard sets with omnis (see 488's robot this year)

I would have to disagree with your logic. You do make a solid point, but by lowering the middle wheel you lose the whole point of making a 6 wheel drive robot. Think of it like tank treads but no messy tread part.:ahh:

Nuttyman54 15-02-2007 20:02

Re: pic: Team 195 driving base 2007
 
Quote:

Originally Posted by nuggetsyl (Post 579053)
I would have to disagree with your logic. You do make a solid point, but by lowering the middle wheel you lose the whole point of making a 6 wheel drive robot. Think of it like tank treads but no messy tread part.:ahh:


I won't repeat all the arguments here, but you can find discussion about it here, and it would appear that a few of your mentors are quite familiar with 6wd systems. You'll also notice that most well-designed tank tread robots have a middle wheel that's slightly lower than the outer wheels, making it essentially a "lowered wheel" 6wd system

There is nothing here that says this is the ONLY way to do 6wd. Your team is living proof of that. I'm just trying to present the reasoning behind the lowered wheel. Many MANY teams use this design, so they can't all be wrong.

Mike Norton 15-02-2007 20:15

Re: pic: Team 195 driving base 2007
 
Quote:

but by lowering the middle wheel you lose the whole point of making a 6 wheel drive robot.

http://www.chiefdelphi.com/media/photos/26869

We only been doing wheel for two year so I am no expert but this system works. it is lowering the center wheel a little.

We did tank track before that and also had a center wheel

http://www.chiefdelphi.com/media/photos/18792

I think our robots has proven to have power

so what he is doing is a good way

Lil' Lavery 16-02-2007 01:01

Re: pic: Team 195 driving base 2007
 
Quote:

Originally Posted by nuggetsyl (Post 579026)
Y lower the middle wheel. Makes no sence. :confused:

In order to ensure better turning, the following relationship is key.

Quote:

longitudinal coefficient of friction x width of wheel base > lateral coefficient of friction (length of wheel base - 4((distance from center of area to center of mass)^2/length of wheel base))
Or simply put, there are a few ways to improve turning. Shorten the wheel base, widen the track width, reduce lateral friction while keeping longitudinal friction high, and moving the center of mass away from the center of the wheelbase.
By lowering the center wheel, you effectively create two 4WDs with a shared center wheel. Each of these has a wheelbase roughly 1/2 of that of the same drivetrain with coplanar wheels. Also, closer the center of mass of your robot is to the center wheel, further it is away from the center of area of both of the wheelbases. Additionally, the traction and width factors should be the same as if you had a coplanar 6WD, and you still achieve many of the other benefits of a 6WD.

(Thanks to Chris Hibner for this terrific white paper on the physics of turning with a 4WD).

Arefin Bari 16-02-2007 01:29

Re: pic: Team 195 driving base 2007
 
Quote:

Originally Posted by nuggetsyl (Post 579026)
Y lower the middle wheel. Makes no sence. :confused:

Alright, I am going to use your team as an example. I can only assume and guess. I know you guys don't lower your middle wheels. Why? I have never been able to get a straight answer from anyone. You guys play around with your tread patterns a lot.

On the other hand, when you do a 6wd and don't lower your middle wheel, the robot is trying to turn on 6 different points. Depending on the friction you create with the wheel/tread you are using, it is very hard to turn unless you lower your middle wheel. While lowering the middle wheel, lots of team work on their CG. If the CG is low and the weight is distributed properly throughout the robot, while turning, the robot turns on 2 (middle) or 4 wheels (using only 4 different points to turn), creating less friction. At the same time, there are always 4 wheels touching the ground. I know wedgetop compresses, so if the weight is distributed properly, you get all 6 wheels touching the ground while going straight or back even if you lower your wheel. It also depends on the team how much they lower their middle wheels. I have seen teams do 1/16, 1/8, 3/16, 1/4, even 3/8 and lot of teams have been successful doing it too.

I sure would like to know how does a team turn without lowering their middle wheels. If there is anyone out there with a proper answer with reasonings behind it, please post.

Now back to topic...

As always, 195's chassis looks awesome. I am digging those wheels. Can't wait to see you guys in person. Let's not burn a victor out right before the final match this time. =)

zander_108 27-02-2007 18:03

Re: pic: Team 195 driving base 2007
 
Quote:

Originally Posted by Arefin Bari (Post 579309)
Alright, I am going to use your team as an example. I can only assume and guess. I know you guys don't lower your middle wheels. Why? I have never been able to get a straight answer from anyone. You guys play around with your tread patterns a lot.

On the other hand, when you do a 6wd and don't lower your middle wheel, the robot is trying to turn on 6 different points. Depending on the friction you create with the wheel/tread you are using, it is very hard to turn unless you lower your middle wheel. While lowering the middle wheel, lots of team work on their CG. If the CG is low and the weight is distributed properly throughout the robot, while turning, the robot turns on 2 (middle) or 4 wheels (using only 4 different points to turn), creating less friction. At the same time, there are always 4 wheels touching the ground. I know wedgetop compresses, so if the weight is distributed properly, you get all 6 wheels touching the ground while going straight or back even if you lower your wheel. It also depends on the team how much they lower their middle wheels. I have seen teams do 1/16, 1/8, 3/16, 1/4, even 3/8 and lot of teams have been successful doing it too.

I sure would like to know how does a team turn without lowering their middle wheels. If there is anyone out there with a proper answer with reasonings behind it, please post.

Now back to topic...

As always, 195's chassis looks awesome. I am digging those wheels. Can't wait to see you guys in person. Let's not burn a victor out right before the final match this time. =)

I strongly agree with your argument. For your question, the Best example of a non-lowered center wheel robot that i can think of is 25 this year. And not only is it 6wd, its 8... If any members from 25 are reading... Enlighten us?

meatmanek 27-02-2007 18:15

Re: pic: Team 195 driving base 2007
 
Quote:

Originally Posted by Arefin Bari (Post 579309)
I sure would like to know how does a team turn without lowering their middle wheels. If there is anyone out there with a proper answer with reasonings behind it, please post.

Team 868 did a 4 wheel, long drivetrain in 2005. How did we turn? Very slowly. But we did drive in a straight line very nicely, something that mecanum and 2WD drives aren't able to do without software help.

What I'd really like to see is an eight wheel drive, with 4 centralized drive wheels that are in contact with the ground all of the time, except when accelerating hard in one direction, or pushed from the top. The front 2 and back 2 would be raised up a bit (1/8" or so), be smaller (to reduce weight), and probably unpowered. This would have the benefits of a long drivetrain, be stable (none of the rocking back and forth I'm guessing you get with a 6WD), and have a more predictable center of turning.

lukevanoort 27-02-2007 18:21

Re: pic: Team 195 driving base 2007
 
Quote:

Originally Posted by Arefin Bari (Post 579309)
I sure would like to know how does a team turn without lowering their middle wheels. If there is anyone out there with a proper answer with reasonings behind it, please post.

Psst, Arefin, read Dr. Joe's post here.


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