pic: Team XBot Mecanum Practice Chassis

[Fred Sayre]

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[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.

[Ben Piecuch]

Beautiful moves! I can't wait to see what the drivers can do with some more practice. One question, any idea why it seems to be so noisy (in the video?) With your custom gearboxes I figured they would be nice and quiet. Or, are the AM Mecanums just that loud? (Sorry for the insinuation Andy/Mark...)

<offtopic>
Dave, it's about that time of the year when the real hints start coming our way. Is this your first "plant" here at the forums for us to deal with?
</offtopic>

Please keep us update with both your mechanical tuning and software tweaking (and methodology, if you will...) Thanks!

BEN

[Madison]

Originally Posted by Ben Piecuch

Beautiful moves! I can't wait to see what the drivers can do with some more practice. One question, any idea why it seems to be so noisy (in the video?) With your custom gearboxes I figured they would be nice and quiet. Or, are the AM Mecanums just that loud? (Sorry for the insinuation Andy/Mark...)

<offtopic>
Dave, it's about that time of the year when the real hints start coming our way. Is this your first "plant" here at the forums for us to deal with?
</offtopic>

Please keep us update with both your mechanical tuning and software tweaking (and methodology, if you will...) Thanks!

BEN

The first gearbox we assembled is markedly louder than the remaining three and it's also the one that's slowest to start, so we're going to tear it down and rebuild it. We think the first handful of shafts we made are inaccurate, so the gearbox isn't square and that's contributing to some binding. The chain is also a bit loose and I screwed up the tensioning mechanism some, so that'll be fixed in the next iteration -- whenever there's time for that.

The wheels, even on carpet, are a bit bumpy because the roller profile only approximates an elliptical shape. More weight may sink the chassis deeper into the carpet and alleviate some of the uneven ride; but that's also contributing to some of the noise you hear. Right now, sans battery, I'd say it weighs about 50 pounds. We'll get an accurate measurement of that tomorrow, we hope.

Edit: There's also no grease in the gears. We need to fix that, too.

[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?

[Rob2713g]

Originally Posted by fsayre

Each wheel/gearbox pod pivots. The tennis and racket balls are what we are testing out for suspension springs.

Could you please provide an up close picture of your suspension or explain it in a little more detail (I'm new to suspensions). Thanks a lot!

[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?