Scenario Regarding Bumpers

I know, it’s been advertised all over, but the whole deal with bumpers in the frame and all that. I’ve been thinking up a scenario purely for fun.

What if the day after bag day, your coach sent out an email saying “We screwed up and the chassis is 3” too big on each side"? How would your team react? Forget how it would be overlooked, just imagine what your build team would do. Michigan teams get 6 hours outside the bag, and could build a bare chassis in the withholding allowance. What would be done in the pits? Could you get a robot together in a short time, and ready for inspection?

We all have heard about Pyrobots building from scratch at the Championship, so it can be done. However, could it be done at a district event? Assuming the overall power level of teams would be lower than Champs, would other teams be willing to dedicate time to help? Could you have a robot done and ready for Quals 1?

Okay, it’s probably not going to happen. If a team forgot about bumpers, could it even be done at all?

It really depends what you need to remove, but I’ve seen teams assemble a robot during practice matches at CVR.

I’m sure other teams are excited to help where needed.

Such an issue can and has been fixed in a single practice day at regionals before. Back when FIRST switched from the sizing box to the frame perimeter measurement, I had several teams at my events show up with grossly illegal robots, because they had built to the same dimensions as the previous year.

All of those teams chose to shorten their robot from to back, affecting their drive train (as the wheels had to move). It involved cutting 10 inches off the front of their robot, reattaching the frame members and adjusting everything else on the robot. It took them all day, but they were legal in time for their first matches. As I recall, they spent the rest of the weekend trying to get their mechanisms working correctly with all of those changes.

Last year, my team had to rebuild our entire robot in the one pit day during the St Louis regional. I suppose if the team made the correct frame and brought it with them it can be done. For Districts it would be much much harder. If your lucky, people would help. As the bumper person on my team, I made sure everything was correct not just with bumpers but how they acted with the frame. Maybe have a person like me, dedicated to bumpers. It helped.

I have heard such stories this year about teams cutting off inches of robot. As a district team, not sure what I would do. My conscience wouldn’t let me stretch the allotted open bag time, but I’d sure think about it. After all, you want the kids to compete, right?


I heard from the LRI at San Diego that there was a team who had their frame perimeter out at the limits of the robot perimeter because they didn’t read the rules, which means they had to drop 7" off the length and 7" off the width of their robot. Apparently they were able to do it because there were no noncompeting teams at SD.

Our rookie year, I understand that another rookie team showed up with an unopened kit of parts. Teams came together (including a few of our students) to get them at least rolling and inspected in time for matches.

If we had to reduce this year’s robot by 3"? Yes, we could if we either went to 4" wheels (which we have in hand at our shop, an hour from our regional) or had the shorter belts needed. Width would be a little harder, as we’d have to move systems supported by the inner sheet of the chassis out to somewhere over the wheels. but not insurmountable. As I think on it, it would be easier to cut the width by 3-1/2" than 3". We would keep the climber and passive receiver. We would probably have to give up the active gear hanger for a passive one due to a lack of space, at least for day one.

I can see it from that street corner, every team should know the rules for this year, nothing was hidden. But, that doesn’t mean this rule isn’t out of left field. Perhaps if someone can explain to me the real reason why bumpers had to be inside the measurement box, when 9 years in a row they did not (the entire history of more than half the teams in FIRST), then I’ll shut up about it. I’d even take a step further to generalize that with the wide array of motors and gearboxes that are available, exchanging an illegal motor for a fairly equivalent legal one is much easier than lopping part of your frame off; moving or modifying a mechanism that sticks too far past the frame perimeter is also easier than lopping part of your frame off. I remain convinced that this particular rule change was not well thought out. Then again, maybe I’m too forgiving to the ignorant.

To answer the OP’s question, yeah, it can be done in your practice day/open bag time, but this complication could have been prevented in the first place, and that irks me.

Frank has explained the reasoning behind it, in a comment on his blog (Scroll down to the comment section):

This is a great question! And it deserves a lengthy answer. We thought hard about the implications of this change this year before we made it.

The change had very specific purposes. We wanted to limit the amount of fuel a team could carry by limiting the volume of the robot, rather than by having an actual fuel count limit, which would have been very difficult to implement logistically. At the same time, we wanted to allow teams to reach over their bumpers with mechanisms, including ball storage mechanisms, if they wished. Also, we wanted to automate scoring of the ‘ready for takeoff’ portion of the game, in which the robots climb the ropes. Thinking through many options for automating this, we recognized a touchpad would be simplest to implement. However, we also wanted a high degree of confidence a robot could only operate the touchpad if it was not in contact with the floor. If you look at the maximum diagonal of the legal robot envelopes, you will see that they are within a few inches of the height of the touchpad itself. We thought it very unlikely that robots will take up the full corner-to-corner diagonal in their designs, or be climbing from their extreme corners, so it’s almost certain that robots that are ‘ready for takeoff’ will actually not be touching the ground, without requiring any referee judgment calls on that, or any delays in scoring. Within one second after the match is complete, unless something unusual happens requiring referee consultation, the score if finalized automatically and ready to be posted.

These two things together – fuel limits with over-bumper mechanisms and automated ‘ready for takeoff’ scoring, meant the simplest way for us to implement size rules was for us to give overall dimensions, rather than some more complex (and likely more limiting for teams) set of frame perimeter plus ‘reach’ dimensions.

We recognize this change may be a challenge for some, but we are communicating this as clearly as we can, and we believe the trade-off is worth it. Fundamentally, it’s very easy to understand. There are two boxes. Your robot, with everything attached, has to fit in one of the two.

As he explains, crafting the rule this way was to give teams maximum flexibility in their design while still enforcing intended game play restrictions. So now that it’s been explained…

Width could do it… would be some ugly work with a chop saw on the cross brace frame members and would have to relocate some electronics. Two main mechanisms (active gear handler & climber) are modular, designed to be removable/replaceable and to not extend out to the frame perimeter (as we had some thoughts of narrowing the robot).

Length would actually be nastier. Definitely would have to repackage the electronics, since they live between the climber and gear handler modules, and redo the drive train.

Doubt we could do both in 6 hour unbag or at a district event. It certainly would be an adventure.

Width would be obnoxious, yet oddly survivable–we built everything to mount to the AM14U3 inner rails so we could get the outer rails off quickly for servicing the wheels. Move some brackets around, and you probably wouldn’t have to do much to the superstructure to get 3" back. Maybe even a touch more, but that would really be a close shave.

Length would be a pain, because we’re right on the legal limit as-is. But from studying pictures, I think we have 3" to squeeze out of the front. Cut the top rails of the superstructure, slide the upright tubes back. Cut the frame on the front side, use whatever belts let us fit wheels in. (Normally I’d want to keep that balanced with the back, but this is a disaster drill.) The intake is going to need a heavy rework job to get tuned just right, but we still have gears and climb to keep us functional for matches while we sort that out.

(Full disclosure, I work at AndyMark and we make the AM14U3.)

Absolutely yes. Did it in 2009 in Virginia for another team. It was ugly, but they competed in their second match.