pic: Team 1687 Doherty Technical Forces - Chassis

[Paul T.]

loading photo ...

Yes its under 112"

[AllenGregoryIV]

What was the intent of the two inset back wheels?

[Paul T.]

Originally Posted by AllenGregoryIV

I hate to be the person to ask but do you have 8" of bumpers on the two front outside vertices, it looks really small in the picture.

Also, what was the intent of the two inset back wheels?

the front two pieces are 8.5" and the back two tucked in wheels allows us to make our bumpers go like this

l l
\_/

it allows us to fit in the cylinder better.

[dodar]

Maybe I just cant visualize the bumpers but I dont see the point of having those back wheels inboard. That also looks like it will greatly affect the maneuverability of the robot.

[Paul T.]

Originally Posted by dodar

Maybe I just cant visualize the bumpers but I dont see the point of having those back wheels inboard. That also looks like it will greatly affect the maneuverability of the robot.

Yeah we thought it may, but were pretty certain that it will be ok.
were also using 4 CIMS and an andymark to power it so we have the power to make up for it

[EricH]

Originally Posted by dodar

Maybe I just cant visualize the bumpers but I dont see the point of having those back wheels inboard. That also looks like it will greatly affect the maneuverability of the robot.

You might ask 179 how having wheels offset in a similar pattern affected them a few years back. I think it was their 2005 robot that had 6 wheels in a diamond-ish pattern; it did fairly well.

It doesn't do much to affect maneuverability, not at that level, at least that I know about.

Visualizing the bumpers... It sounds like an interesting idea; I assume that bumper supports just aren't shown in this render. (Magic doesn't count as a support, sorry. Neither does simply constraining in CAD...)

[Paul T.]

Originally Posted by EricH

You might ask 179 how having wheels offset in a similar pattern affected them a few years back. I think it was their 2005 robot that had 6 wheels in a diamond-ish pattern; it did fairly well.

It doesn't do much to affect maneuverability, not at that level, at least that I know about.

Visualizing the bumpers... It sounds like an interesting idea; I assume that bumper supports just aren't shown in this render. (Magic doesn't count as a support, sorry. Neither does simply constraining in CAD...)

you only see the chassis in the picture, we are planning to use the full 20 lbs for bumpers to include almost all mounting in the bumpers.

[AllenGregoryIV]

Originally Posted by Paul T.

you only see the chassis in the picture, we are planning to use the full 20 lbs for bumpers to include almost all mounting in the bumpers.

I'm still not sure if I understand this comment with how I understand R29.

The bumper hardware can be extensive but there still has to be a frame perimeter for which the bumpers are supported against. When you wrap the string around your robot with out the bumpers where does the frame perimeter support your bumpers?

[JesseK]

I agree with Allen. The bumpers (or any attached bumper hardware) do not define the frame perimeter -- only what's on the robot defines the frame perimeter.

Originally Posted by Glossary of the FRC Manual

FRAME PERIMETER: the polygon defined by the outer-most set of exterior vertices on the ROBOT (without the BUMPERS attached) that are within the BUMPER ZONE. To determine the FRAME PERIMETER, wrap a piece of string around the ROBOT at the level of the BUMPER ZONE - the string describes this polygon.

Since your wheels & axles define your perimeter, the plywood backing of the bumpers must butt up against them at every exterior vertex per R22.

Additionally, that is definitely a bit of stretch for the definition of "bumper mounting hardware" that I wouldn't stake my season on without a clearer definition from Q&A.

Fortunately, it looks like it's easy to accommodate hard mounts on the frame itself for bumpers & a frame perimeter everywhere except the front corners. Quite honestly, nothing defines what materials hard frame mount must be made out of, so it can technically be 1/32" sheet metal for the front corners.

The perimeter shape in a nice way of ensuring the 112" distance is met. Kudos to whomever thought of that idea on your team!

[Nuttyman54]

Originally Posted by JesseK

Fortunately, it looks like it's easy to accommodate hard mounts on the frame itself for bumpers & a frame perimeter everywhere except the front corners. Quite honestly, nothing defines what materials hard frame mount must be made out of, so it can technically be 1/32" sheet metal for the front corners.

I think this is what Joe is referring to. What's shown is only about 4" tall, they have quite a bit of room in the 6" of bumper zone above that to put a "frame perimeter". They'll be putting small/thin frame members in this area to meet the perimeter/frame rules, but the majority of the structure behind the bumpers is part of their mounting hardware.

[The_ShamWOW88]

Looks like a unique design. Can't wait to see it in action at WPI.

[Jeffrafa]

On a slightly different note, do I spot two pneumatic actuators on each gearbox?

And a pretty interesting layout of 4 larger actuators in the top view, I am very curious to see how this turns out.

Good luck!

[dodar]

Originally Posted by EricH

You might ask 179 how having wheels offset in a similar pattern affected them a few years back. I think it was their 2005 robot that had 6 wheels in a diamond-ish pattern; it did fairly well.

It doesn't do much to affect maneuverability, not at that level, at least that I know about.

Visualizing the bumpers... It sounds like an interesting idea; I assume that bumper supports just aren't shown in this render. (Magic doesn't count as a support, sorry. Neither does simply constraining in CAD...)

I do believe 179 did it in 2008 as well. They had a pretty wicked turn rate. But it might have just been a 3-wheeler with the front wheel being a swerve module.

[Paul T.]

Originally Posted by dodar

I do believe 179 did it in 2008 as well. They had a pretty wicked turn rate. But it might have just been a 3-wheeler with the front wheel being a swerve module.

http://www.chiefdelphi.com/media/photos/21631

that's actually what inspired it.

[dodar]

Originally Posted by Paul T.

http://www.chiefdelphi.com/media/photos/21631

that's actually what inspired it.

Well that was their 2005 bot not 2008.