pic: Team XBot Mecanum Practice Chassis

[Fred Sayre]

loading photo ...

[Tom Bottiglieri]

Looks awesome! The modules look very robust and pretty. Some plating on that thing would make it look like a beast.

I have some questions though. Did you notice any flex in the frame when driving? It looks to me like it is all bolted together. I know people have had problems with frame flex in mecanum drive trains. One of the wheels would lift off the ground, messing up the resultant total force vector, sending the robot in another unforeseen direction.

[Lil' Lavery]

Originally Posted by Tom Bottiglieri

I have some questions though. Did you notice any flex in the frame when driving? It looks to me like it is all bolted together. I know people have had problems with frame flex in mecanum drive trains. One of the wheels would lift off the ground, messing up the resultant total force vector, sending the robot in another unforeseen direction.

I beleive that they have a suspension (similar to 40's) on each wheel module to attempt and accomodate for any bending, imprecision, or minor terrain features.
Certainly a great looking protoype, how much does it weigh?

[Fred Sayre]

Originally Posted by Tom Bottiglieri

Looks awesome! The modules look very robust and pretty. Some plating on that thing would make it look like a beast.

I have some questions though. Did you notice any flex in the frame when driving? It looks to me like it is all bolted together. I know people have had problems with frame flex in mecanum drive trains. One of the wheels would lift off the ground, messing up the resultant total force vector, sending the robot in another unforeseen direction.

Check out http://www.chiefdelphi.com/forums/sh...ad.php?t=49213 for a better description.

Each wheel/gearbox pod pivots. The tennis and racket balls are what we are testing out for suspension springs. Right now, we are having more of an issue making the friction in the drive pods equal (we had one really beat up CIM in this chassis). If one wheel takes a second longer to start spinning then the same issue occurs.

Overall though our drivers were starting to be able to compensate for the quirks in the movement, so when we get it nice and tuned it should only get better

[dlavery]

Looks very nice.

How well does it handle stairs?

-dave

[Madison]

Originally Posted by dlavery

Looks very nice.

How well does it handle stairs?

-dave

It's too much fun to drive and a lot of fun to watch. If it needs to climb stairs, I'll make it climb stairs.

[deshirider430]

Lavery as in this years game is going to have stairs!? Just playing, thats a really nice frame and set up.

[Timmyd]

Originally Posted by dlavery

Looks very nice.

How well does it handle stairs?

-dave

HINT HINT OMG HINT!!!!!!!!!

lol something that could climb stairs hmmm
*tears apart an iBot* MINE CAN NOW

[Rich Kressly]

I'll never get tired of watching one of these guys move. Excellent job getting to this point for sure. As for Dave and the stairs, just ignore him like the rest of the FRC GDC does...

[Billfred]

I was looking at the full-size version of the picture, and it looks like the actual frame is just four lengths of box tubing and two C-channels bolted together. I like the layout--is there more to it, or am I just not seeing it?

[Fred Sayre]

Originally Posted by Billfred

I was looking at the full-size version of the picture, and it looks like the actual frame is just four lengths of box tubing and two C-channels bolted together. I like the layout--is there more to it, or am I just not seeing it?

Nope, thats it! The underside of the C channel is milled out to accommodate the suspension, holes were drilled for where the drive pods rotate, and 8 holes were drilled to bolt the tube and C channel together.

[AdamHeard]

Originally Posted by fsayre

Nope, thats it! The underside of the C channel is milled out to accommodate the suspension, holes were drilled for where the drive pods rotate, and 8 holes were drilled to bolt the tube and C channel together.

How durable is that setup?

[Cody Carey]

That appears to be the max size of a drive base according to last years rules, right? For a competition bot, would you scale that design down somewhat in order to add a protective structure around the outside? or would you just rely on the fabric bumpers? It would seem to me that the channel used on the outside would bend/dent easily, and no amount of suspension will keep a Mecanum drive operating correctly if one or two of the wheels are suddenly bent at some odd-angle. The video looks very nice indeed, and I can't wait to see what the drivers can do with a bit of practice

[Madison]

Originally Posted by Cody C

That appears to be the max size of a drive base according to last years rules, right? For a competition bot, would you scale that design down somewhat in order to add a protective structure around the outside? or would you just rely on the fabric bumpers? It would seem to me that the channel used on the outside would bend/dent easily, and no amount of suspension will keep a Mecanum drive operating correctly if one or two of the wheels are suddenly bent at some odd-angle. The video looks very nice indeed, and I can't wait to see what the drivers can do with a bit of practice

The chassis is about an inch short of last year's maximums in all directions. If you look at some of our past work, you'll see that I don't typically add structure to things for protection, but since these wheels are quite expensive, this chassis was kept simple to facilitate accepting bumpers. Also consider that it's for practice and won't be seeing competition, so there was no use in wasting time and resources on making it stronger than it needs to be for learning, practice and demonstrations.

[Fred Sayre]

Originally Posted by AdamHeard

How durable is that setup?

It hasn't broken yet

The frame seems plenty rigid and sturdy. We have not really ran into anything yet, but with bumpers and such it should be fairly protected. How it deals with the strains of the rest of the weight of the robot we still have to evaluate.