New size/bumper rules that every team should know

Two subtle changes to the rules that have huge impact, and the potential to really hurt some teams if they’re not careful.

<R03>Maximum ROBOT size, including BUMPERS and all extensions, must be constrained to one of
two volumes:
A. 36 in. by 40 in. by 24 in. tall (~91 cm by 101 cm by 60 cm tall).
B. 30 in. by 32 in. by 36 in. tall (~76 cm by 81 cm by 91 cm tall).
The ROBOT must remain constrained to the maximum inspected volume at all times during the
MATCH (i.e. A ROBOT may not switch between volume A and volume B without being reinspected).

The first big change: Bumpers are now included in the robot size limit. This means that your physical robot must take into account the ~3.25" on each side a bumper will take up, but also take into account the fact that bumpers are soft, squishy, and tend to shift, and are probably not as dimensionally reliable as what we’re used to using as a frame perimeter defining part. Leave extra room, and don’t forget the bumper size entirely.

However, bumpers must still be removed for inspection so that the robot can be weighed. So don’t make them 100% integral to the frame just yet.

The second, more subtle change. For the first time since 2009, the robot is limited to the same size in its starting configuration as during the rest of the match. However, the rule is not the same as the 2009 rule. 2009 was frame perimeter based, and banned any extension over the starting perimeter. If you chose to be small, you were stuck small.

This year, however, it’s a fixed maximum size. If you want to reach over the bumper to expand your intake, grab a rope, or anything else, you can do this, but only if your base/frame perimeter is smaller than the maximum size. Say, for example, you choose the 36"x40"x24" size. A drive base/bumper assembly built at 36"x40" cannot have a drop-down intake of any sort, and will be constrained to a bumper-cutout intake with 6" on each side (another change, down from 8"). However, if the team instead builds their bot 36"x30", they have a full 10 inches outside of the bumper to extend and build anything they want. This mechanism must still retract due to <R02> for the start of the match.

Plan your drive base carefully. Bigger is not necessarily better, and may lock you into a design and prevent you from duplicating something cool you see at a first event.

Whether or not the bumpers are included in the perimeter is contrasted in R01 and R03. Has FIRST said that the bumpers are included in the perimeter? If so, please post the link.

<R01> and <R03> do not conflict. <R01> states that the robot must have a FRAME PERIMETER, meeting the fixed, non-actuating, etc. requirements we all know and love. The FRAME PERIMETER is referenced in <G09>, which deals with interactions between robots, <R02>, which states that everything except the bumpers must start (but not necessarily end) the match inside the frame perimeter, and repeatedly throughout the bumper rules, which deal with how the bumpers must attach to and interact with the FRAME PERIMETER. However, <R03>, which deals with the actual size limit of the robot, clearly includes the bumpers in this, and does not reference the FRAME PERIMETER in any way.

I believe the frame perimeter rules are there to help define the bumper rules (I.E if you have a V robot frame you don’t need to put bumpers inside the V) and to define the starting configuration. There are no frame perimeter limits only volume limits.

This is immediately what I thought of as well. The last 4 seasons have had very different bumper and frame perimeter rules - FIRST and the GDC should highlight this subtle (but major) change as much as they can over the next 10 days or so.

R22. ROBOTS are required to use BUMPERS to protect all outside corners of the FRAME
PERIMETER. For adequate protection, at least 6 in. (~16 cm) of BUMPER must be placed on
each side of each outside corner (see Figure 8-1). If a FRAME PERIMETER side is shorter than
6 in. (~16 cm)

This is reduced from 2016’s 8 inches.

This seems to defeat the purpose of bumpers, at least how they’ve been used the past few years, doesn’t it?

They used to guarantee about 6 inches of distance between “internal components” of robots. With this game, everything will always be inside the frame perimeter, but the grace distance that the bumpers used to provide doesn’t exist. Teams will have to be careful to either build robustly, or be well inside the bumpers.

Bumpers may or not actually provide any protection.

This makes the real volume less than the stated volume.

I’m not sure I see your point…
At the start of the match all parts of the robot except the bumpers must be within the frame perimeter (which does not include the bumpers) as typical in FRC. The grace distance is still there. The only things that are vulnerable are frame perimeter extensions that deploy after the match starts as usual.

It doesn’t seem very different to me in terms of protection.

Two minimalist, full size, box-on wheels robots will still collide bumper to bumper, with 6" between the internal parts of their robots. Of course, now they could hypothetically expand into the 3 inch region directly above, but not beyond, the bumper in any direction, but they don’t gain much by doing this. On the more extreme end, teams that voluntarily build small can reach beyond the bumper. The rules of the past few bumper games still apply – you put mechanisms beyond your frame perimeter at your own risk, and are penalized if one of them reaches into the protected frame perimeter of another team.

It’s dramatically different in terms of the size you should build your robot if you want to expand though, and that’s why I brought this up. I expect some teams to build very, very small bases which expand a great length in multiple directions, perhaps even with drivetrain components on the expanding parts, and don’t want teams to be caught off-guard that this is not only legal, but that their “standard” drive base designs may prevent them from adding these features.

Oh whoops, I feel silly, I misread the rules on it. :frowning:

I’m afraid there’s going to be several teams unable to compete at their event because they show up with bumpers outside the sizing box and have no way of cutting 5-6" both directions. Glad I’m not the LRI that has to tell them that.

Not sure if this is the right place but would these bumpers be legal?


The gap is 13 inches but there will be a beam above the bumpers connecting the two sides so that the frame is technically all closed.

edit the two shorter sides are both 6 inches.

That would not be legal because the frame perimeter is measured as a convex polygon wrapping around the robot, so the two pieces pointing inward would not be considered bumpers.

Before I answer…
What is your Frame Perimeter? Read R01, particularly the blue box. Now read R22, including the blue box, and R29G. I’ll explain in the spoiler, but I’d like you to read those rules first.

The Answer

Your frame perimeter is a convex polygon formed by the outside corners of your robot, per R01. R22 says that you have to have 6" of bumper on each side of each corner of the frame perimeter, and R29G says that bumpers have to be mounted to the frame perimeter. The portion of the pictured bumpers inside the points are not protecting 6" of frame perimeter, and they aren’t mounted to it. The robot portrayed has a rectangular frame perimeter, and the bumpers aren’t going to be legal like that.

R23. BUMPERS must be located entirely within the BUMPER ZONE, which is the volume contained between the floor and a virtual horizontal plane 7 in. (~17 cm) above the floor in reference to the ROBOT standing normally on a flat floor.

New this year,the top of the bumpers is 7" this year (think bumpers end up 5.5-6.5" tall with fabric. My memory says last year the bumper zone was 5-12" off the ground.

This rule also makes it so the square KOP chassis can not be legal if it is made to the dimensions in the instructions

The rules do not say how much of the bumper has to touch the frame vertically, only how much horizontal gaps you can have. (I believe, I’m not a rules expert, but read through the rules twice. Think that was the same as last year.)

yes, but it must be firmly supported. I would recommend ~1" of vertical contact at a minimum.

I’m still a little unclear on the frame permiter. If you choose the 30x32x36 size, does that mean you need to account for the ~3.5" of bumper on each side, leaving you with a max frame size of 23x25?? That seems a bit ridiculous. Granted it’s probably doable, but I can’t imagine FIRST having that tight size constraints

R03 is very clear that the bumpers are included in the volume limits, and R01 defines the frame perimeter as excluding the bumpers. So yes, you need to account for the bumpers, and the frame would be about 32x25" max for the tall volume, or about 29x33" for the short volume…