Chief Delphi

Chief Delphi (http://www.chiefdelphi.com/forums/index.php)
-   Technical Discussion (http://www.chiefdelphi.com/forums/forumdisplay.php?f=22)
-   -   pic: FRC488 - Six Wheel Drive Chassis (http://www.chiefdelphi.com/forums/showthread.php?t=50864)

Madison 02-01-2007 22:05

pic: FRC488 - Six Wheel Drive Chassis
 

DanDon 02-01-2007 22:06

Re: pic: FRC488 - Six Wheel Drive Chassis
 
A couple of questions:

Does that have any rocker in it? And is that 25 or 35 chain?

Joel J 02-01-2007 22:28

Re: pic: FRC488 - Six Wheel Drive Chassis
 
Why omniwheels on a 6WD?

EricH 02-01-2007 22:30

Re: pic: FRC488 - Six Wheel Drive Chassis
 
Quote:

Originally Posted by Joel J. (Post 547166)
Why omniwheels on a 6WD?

Turning, I'd say. Instead of lowering the center wheel, why not use omni's? It's more stable and more maneuverable. (It's also easier to spin around by hitting.)

Gdeaver 02-01-2007 22:31

Re: pic: FRC488 - Six Wheel Drive Chassis
 
If the bumpers are back and the design is like 2006, then the next step is to add mounting to this frame that would allow the bumpers to be a structural element. If the rules allow forget home center plywood. Baltic birch "wood" be a good choice.

Cody Carey 02-01-2007 22:32

Re: pic: FRC488 - Six Wheel Drive Chassis
 
Not necessarily more maneuverable, But I bet it is nice to have the 'bot spin around it's center set of wheels instead of whichever four happen to be touching the ground :rolleyes:

s_forbes 02-01-2007 22:38

Re: pic: FRC488 - Six Wheel Drive Chassis
 
Wow, looks light! Do you have an estimated weight for the entire drive base?

And on the subject of omniwheels: It looks like with the setup you have it would be very easy to swap them for traction wheels if they are needed. I guess that would be decided in testing.

MikeDubreuil 02-01-2007 23:07

Re: pic: FRC488 - Six Wheel Drive Chassis
 
Can you explain why you chose not to have a cross brace? I'm not a mech-e but I would guess you need one.

Madison 02-01-2007 23:24

Re: pic: FRC488 - Six Wheel Drive Chassis
 
Quote:

Originally Posted by dhoizner (Post 547159)
A couple of questions:

Does that have any rocker in it? And is that 25 or 35 chain?

The wheels are all in line -- there's no 'rock' at all. The chain is #25.

Quote:

Originally Posted by Joel J. (Post 547166)
Why omniwheels on a 6WD?

Because the center wheel is not lowered at all, at least one outside set of wheels should be omniwheels to alleviate friction while turning. I chose to put a set on each end because there's no penalty to in line pushing force, generally, and I like to subtley encourage our drivers to avoid conflict. :)

Quote:

Originally Posted by Gdeaver (Post 547169)
If the bumpers are back and the design is like 2006, then the next step is to add mounting to this frame that would allow the bumpers to be a structural element. If the rules allow forget home center plywood. Baltic birch "wood" be a good choice.

I'm now looking at a mounting scheme that will accept bumpers and protect the wheels from impact. I've never put bumpers on a robot before, so I'm looking at examples of others' work to get an idea how to best accomodate the additional weight of the bumper assembly.

Quote:

Originally Posted by Cody C (Post 547170)
Not necessarily more maneuverable, But I bet it is nice to have the 'bot spin around it's center set of wheels instead of whichever four happen to be touching the ground :rolleyes:

Our 2005 robot had a lowered center wheel and the tipping action drove me and our drivers crazy. It's an impact to the system each time the robot's inertia shifts and that starts to lead to annoying things like loosened bolts and the like. Practically, it's cheaper and easier for me to make omniwheels than it is to make traction wheels and it's certainly cheaper than buying them.

Quote:

Originally Posted by s_forbes (Post 547172)
Wow, looks light! Do you have an estimated weight for the entire drive base?

And on the subject of omniwheels: It looks like with the setup you have it would be very easy to swap them for traction wheels if they are needed. I guess that would be decided in testing.

As shown -- which includes everything but stiffening gussets and a base upon which to mount electronics, it's 29.5 lbs.

The omniwheels are riding on 5/8" keyed shaft, while the AndyMark performance wheel is broached for a 1/2" hex shaft. It'd be relatively easy to change out a set of omniwheels for a set of traction wheels with a little bit of forethought. Namely, I'd need to make some shafts that are 5/8" diameter with keyway on one end and 1/2" hex on the other.

Quote:

Originally Posted by MikeDubreuil (Post 547189)
Can you explain why you chose not to have a cross brace? I'm not a mech-e but I would guess you need one.

I'm waiting on the game before adding cross-bracing since I'm not sure if I'll need a scoop or something on one or both ends. I'd like to, if weight allows, put an aluminum plate (1/16" or so) across the bottom to add rigidity.

Gdeaver 02-01-2007 23:33

Re: pic: FRC488 - Six Wheel Drive Chassis
 
I noticed that the front and rear c channels are notched for the drive rails on top and bottom. This could be a weak point. Shouldn't the drive rails fit inside the c channel leaving the channel uncut ?

dlavery 03-01-2007 00:00

Re: pic: FRC488 - Six Wheel Drive Chassis
 
M -

Looks quite nice, and you have obviously put a lot of work and thought into the design. The efforts to minimize the total weight are obvious. The biggest concern you may have is strength in the event of an impact or collision. You might consider making the frame members out of rectangular tube instead of channel. Given the amount of material you are removing, the additional weight from the fourth side of the tube will be minimal, but there will a considerable increase in stiffness of the frame assembly.

Just out of curiosity, what is the spacing between the wheel sets? Is it sufficient to cross a 20-inch wide, 16-inch deep, water-filled moat, should that capability ever be necessary?

-dave

Cody Carey 03-01-2007 00:02

Re: pic: FRC488 - Six Wheel Drive Chassis
 
Oh goodness.

ChuckDickerson 03-01-2007 00:15

Re: pic: FRC488 - Six Wheel Drive Chassis
 
Here we go again...

Madison 03-01-2007 00:17

Re: pic: FRC488 - Six Wheel Drive Chassis
 
Quote:

Originally Posted by dlavery (Post 547210)

Just out of curiosity, what is the spacing between the wheel sets? Is it sufficient to cross a 20-inch wide, 16-inch deep, water-filled moat, should that capability ever be necessary?

-dave



;)

Jeff K. 03-01-2007 00:22

Re: pic: FRC488 - Six Wheel Drive Chassis
 
Quote:

Originally Posted by dlavery (Post 547210)
Is it sufficient to cross a 20-inch wide, 16-inch deep, water-filled moat, should that capability ever be necessary?

-dave


Any crocs?

CRIKEY!


All times are GMT -5. The time now is 23:15.

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