This is the BUMPERS companion to my annual Robot and Inspection rules changes topic. As with that one, I will make this a wiki so we can keep the original post up to date as Q&As and Team Updates happen. Feel free to DM me with corrections to keep the topic easy to read, especially on kickoff day.
I will not note all rule number changes, though I will note when rules are removed or added.
Additions, changes, and clarifications in Team Updates and due to Q&A will be in bold font. Such deletions will be indicated by strike out.
Open Q&A questions are indicated in italic font
Last updated based on Team Update 01 and Q&A as of midday 10 January, US Central time.
Throughout: The FRAME PERIMETER is now called the ROBOT PERIMETER.
The introduction now provides less intent/purpose stuff. It also now allows that measurements are nominal and allows an additional tolerance of ÂĽ".
R401: Bumpers all around. The permitted gap in the bumpers is up from ½" to 1¼". Q&A 15 confirms U shaped robots must still have convex bumpers, apart from the gap
R402: BUMPER construction. This was R408 last year, and has been restructured completely. It describes four components:
A. Padding; many more options than pool noodle this year! Minimum depth is 2¼", minimum height is 4½".
B. Backing;
still at least 4½" but no upper limit.
Materials and attachments appear unrestricted.
The backing must cover the entire rear of the padding, but may extend higher or lower. Q 25 asks for confirmation of this and no maximum height
Q&A 12 confirmed no minimum thickness
C. Cover: Fabric which covers all outward, upward and downward facing surfaces of the padding such that no padding is exposed to interaction with the FIELD or other ROBOTs. That’s it. There’s stuff about color in R411, but that’s it.
D. Fastening System: Essentially the same as last year’s R408G, but removable fasteners may now be weighed either with the ROBOT or the BUMPERS.
R403 BUMPER extension limit (new): No more than 4" from the ROBOT PERIMETER.
R404 BUMPERS must be soft. Extends the hard parts zone to 1ÂĽ" from the ROBOT PERIMETER, and soft parts must be at least 2" past that. The figure also shows at least 2ÂĽ" of padding from the backing based on R402A.
R405 Bumpers interact with bumpers. Replaces last year’s R402 BUMPERS stay low. The Bumper zone must now be full of padding, but is only 3¾" tall, from 2½" to 5¾" from the carpet.
R406 Fill BUMPER corners Replaces R409. Corner padding must be uncompressed, which means no bending around a corner sharper than 135°. The corner padding must extend to at least 2¼" from the corner. Mitered corners in separate bumper pieces are not allowed. TU01 added a case to the blue box permitting bumpers with separate segments which meet at the corner, provided the padding covers the corner coming only from one face.
R407 BUMPERS shouldn’t be wedges. Same intention as part of R408C, but much more simply stated with four blue box examples. Q26 asks about cylinders as wedges.Curiously, all of the blue box examples regard the padding; none address using the backing as a wedge.
R408 Weight limit with BUMPERS Replaces R407. Total weight limit is now 135lb, but you can let more than 15lb be the bumpers now.
R409 BUMPERS shouldn’t move: no changes from last year’s R403.
R410 BUMPERS must come off. Added “quick and easy” to last year’s R404.
R411 BUMPERS indicate your Alliance. Essentially the same as last year’s R405, except that the blue box about the side facing the robot is now in R402c.
R412 Team number on BUMPERS:
numbers can now be smaller, 3Âľ" vs 4"
sharp corners are now 135°, not 160°
Deleted rules:
R408 is mostly deleted, with various bits dispersed to other rules.
The new language about tolerances is a bit confusing to me.
From section 8.4:
All dimensions specified in this section are nominal and will be measured during inspection with a tolerance of ¼ in. (~6 mm) unless otherwise specified. This means that maximums specified have a tolerance of + ¼ in. and minimums specified have a tolerance of – ¼ in
So in R402a, the 2-1/4 " minimum padding can be 2". Cool
But then in R404 it says “at least 2in”, which means 1.75" is OK? Or is that including the tolerances in R402a?
With the quarter inch aside, I read this as that the overall thickness must be 2¼", but it may only be 2" past the last hard part. I’m thinking this is sort of like the minor protrusions in the ROBOT perimeter rule - if you have a bolt head or something that sticks up ¼" into the that 2¼", it’s OK.
Note that robot weight limit is 115 so 20 pounds are reserved for bumpers.
The 2.25” minimum padding thickness is from R402. R404 is requires 2” from any hard part, including fasteners etc. So for example if you used 3/4” plywood backing but your screws stuck out 1/2” beyond the backing, R404 would require 2 1/2” of padding against the backer so that there was still 2” beyond the screws.
Thanks! I was so focused on the possible materials and the fact that multiple types, shapes, and layers were permitted I glossed over the minimum dimensions. I’ve fixed this in the OP (that’s one of the reasons it’s a wiki). _____________________________________________________________
Sure, but my point was that if you build [for example] a 60lb robot, you could in theory build 75lb bumpers. In effect, the BUMPERS could become a single piece exoskeleton, like a nautilus, conch, snail, etc. [Just lucky it’s introduced in a sea-themed game, I’m sure!] Warning: Especially from here on in this post, I’m interpreting rules from multiple years. I think I’m right, but these are my interpretations, not anything official.
How useful such a thing would be and how it would be useful depends on the meaning of “rigid fastening system”. If, as hinted by the parenthetical
(e.g. not attached with hook-and-loop tape, tape, or cable ties)
means only that the fasteners themselves are rigid, it leaves room for the ROBOT PERIMETER to be mounted to the BUMPER with additional shock absorption, provided all of the “hard stops” were rigid parts or rigid fasteners.
Even if it means that the BUMPERS and ROBOT PERIMETER have to be rigidly mounted to each other, there’s no requirement that the rest of the robot has to be rigidly attached to the ROBOT PERIMETER; I haven’t seen any rules this year that would have changed the legality of Darth Theta, 4907’s jumping robot from 2022, whose FRAME PERIMETER and robot chassis were actively articulated relative to each other, but the FRAME PERIMETER was ruled as not being articulated, from which I infer that such articulation is meant only among the pieces of the FRAME/ROBOT PERIMETER.
I might have missed this, but doesn’t R406 kill having multi-piece bumpers that overlap or touch at the corner of the robot? Since the separation point could be considered a gap.
The key thing here about R406 is [emphasis mine] “Corner joints must be filled … with no gaps or voids.”
Having separate segments for each side is not forbidden, but if so, the corner must not be mitered, which would leave a gap. See figure 8-7, sub-figure at lower right, and the blue box bullet B about examples that do not meet 406:
Separate bumper segments meeting at a miter in the corner are not considered to “fill” the corner due to the fabric covering.
Separately, R402B has “(i.e. padding is not cantilevered other than in the corners)”. I read this to mean that the padding in the corner may be attached to the backing on only one side [that is, cantilevered], in the style 456 (the team Chuck Dickerson mentors) has used for years. I’m not sure if you can see it in the corner nearest the camera, but the bumpers are in four linear segments, with the padding in each corner attached to the segment to its left, as viewed from outside. I took this photo at 2024 Bayou shortly after applying their inspection sticker. I usually take a close-up photo of each inspection sticker I initially sign after it’s on the robot, followed by one of the robot and the crew I worked with for inspection.
Team Update 01 had two changes to BUMPER rules. The second clarifies exactly what the previous post was about, specifying this IS allowed.
The first clarifies that the BUMPER Cover must completely cover the exposed PADDING, implying that the Backing and Fastening System may be uncovered, as shown in the oritinal figures.
Do the new bumper rules prevent you from having gaps between the bumper and the structural components of the robot? Given the way the rules are written if my robot was the shape of an X as viewed from above it would have a square robot perimeter as defined in R101. The requirement in R401 is just that you protect the robot perimeter. There are no specifications as there were before about gaps between the bumper and frame, thus the gaps could be quite large.
This would be a pretty bad way to allow a team to construct their bumpers, so I’m wondering if I’m missing something.
I am pretty sure we concluded that an x shaped robot frame (square robot perimeter) is permitted (now with R410 gone).
All of this allows for using the bumper as more of a structure element than before (e.g., using steel angle as part your fastening system to get weight down low and provide support to the bumper)
Adding to Skyehawk’s response. The bumper task force wanted to eliminate some of the bumper rules that lead to failed inspections over poor construction quality or similar but wouldn’t put other teams or the field at significantly increased risk. This does mean some of the rules changes allow teams to make decisions that will dramatically harm themselves if they choose to build fragile bumpers and robots.
When reading the new bumper rules, forget the old rules and any perceived intent behind them. The bumper rewrites come from changes in intent. Bumpers used to be a single design component that would protect almost any robot in almost any situation, and not a significant part of the design challenge. This hasn’t really worked the last few years hence the task force last summer. The new rules were drafted with the idea that bumpers are a part of the design challenge and that there is no longer a simple easy construction that will protect any reasonable robot in the types of collisions that are common now. So teams should think about their bumpers and robot as a whole and design something that will survive the rigors of gameplay as best they can. This could mean stronger bumpers over a fairly fragile bot, or fairly weak bumpers over a very strong bot.
Disclaimer: I was on the bumper task force over the summer and I am attempting to give a reasonable reflection of the task force’s opinions, but that might not reflect the opinions of every member or the GDC who made the actual decisions after we submitted our recommendations.
This sentiment seems to say “well, people kept breaking 3/4” plywood, so whatever… let them figure it out on their own.” I’m hoping HQ takes some notes this season and puts together a rookie recommendation packet, or something to that effect, that guides teams toward best practices.
The manual does reference the old bumper guide and the Kitbot instructions as bumper reference. An up to date bumper guide with foam and backer recommendations would be good for next year though. 3/4" plywood mounted to a basic drivebase as in 4 separate pieces will survive on most bots particularly low resource bots that are light, and slow. But 3/4in plywood doesn’t cut it for the mid to top end of bots and we wanted them to be able to use what ever materials and fabrication they are most comfortable with.
