Re: pic: Team 1687 Doherty Technical Forces - Chassis
 

To answer some questions:

-We have complete confidence in the turning and stability of this drivetrain. In addition to past success by team 179 and others with this style of drive, we've done the math -- it will turn with comparable scrub to a 38*28 6WD. The system is just structured somewhat differently than 179's, taking liberal inspiration from the West Coast Drive, the sheet metal work of teams 148, 228, 488 and others, and 2791's "belt in tube" system.

-Why bother? Some reasons we considered:

• Tucks us further back in the 54" cylinder, giving us much needed room in the front for our multi function drop down system
• (slightly) reduces perimeter for a given rectangular footprint, giving us a bit more space within the robot. The impact is slight, but it's enough to make all our desired functionality fit comfortably.
• During strategy analysis, we foresaw frequent head-on collisions due to cross-field traffic, and situations where a defender may attempt to blockade access of some part of the field. The beveled edges allow our robot to glance off and pass by other robots more effectively (I believe this was also the intent behind 179's design)

-Here's a sketch showing our robot's bumper perimeter. The two front segments are each the minimum length. Framing which supports the bumpers on this odd-shaped perimeter not shown, much of the real load-bearing hardware does come off with the bumpers, but there is enough support on the robot to legally support the bumpers, and create a well-defined frame perimeter for inspection.

Re: pic: Team 1687 Doherty Technical Forces - Chassis
 

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?

Re: pic: Team 1687 Doherty Technical Forces - Chassis
 

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.
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!

Re: pic: Team 1687 Doherty Technical Forces - Chassis
 

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.

Re: pic: Team 1687 Doherty Technical Forces - Chassis
 

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

Re: pic: Team 1687 Doherty Technical Forces - Chassis
 

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!