Bumper Zone Limitations

[Dillon Carey]

Bumpers have been around for quite a while now, and the Bumper Zone has pretty much always stayed the same. The main rule I would like to address is the height limitations on the bumper zone. It has been 2"-10" off the ground for as long as I remember. This may have been a good height when bumpers were introduced (2006 I believe), however, since then the average wheel size has shrunk dramatically. Mounting bumpers 2" off the ground is extremely inconvenient in many cases and I don't see a reason the rule shouldn't be changed to 1" off the ground.

On a side note, forcing the bumpers to start/stay in the bumper zone really limits a teams creativity when it comes to flop bots or other interesting configurations. (check out team 16 in 2008 for a good example)

[jee7s]

The bumper zone was higher in 2010 to accommodate the soccer balls, as I recall. Though, I don't recall the exact height range.

I'm not the GDC or anything, but....IMHO the whole point of the bumper spec is to make sure that two robots both have a deformable surface (the bumper) at the same height for interactions. This way, the energy of the impact goes into the bumper and not into metal. Allowing teams to move the bumpers outside of the bumper zone really defeats this purpose. And, from my past experience with FRC, I can assure you that a bumper-to-bumper interaction is much friendlier to a frame than a metal-to-metal one.

So, yeah, the whole bumper zone could come down an inch or so, but GDC would still need to preserve the requirement that the bumper-to-bumper interaction occurs.

[NickCrispie]

In 2010, the bumper zone was 10-16 inches, much higher than it has been the past couple years.

Moving the bumper zone to 1 inch above the floor is not necessarily a bad idea, but if the change were to take place, the bumper zone upper limit would likely have to be simultaneously moved down to 9 inches (or lower). Bumpers are constructed to be 5 inches tall, and the bumper zones are so spaced such that there will be a minimum of 2 inches of overlap no matter where each team puts their respective bumpers, limiting robot-bumper contact and instead ensuring safer bumper-bumper contact. While flexibility in the rules allows for innovative designs to be developed, if the bumper zone was given too much freedom, the safety objectives that the rules are meant to ensure would likely be compromised.

[qnetjoe]

One of the reasons for having it 2" off the ground might have to do with the cog of robot(s) during a moderate speed collision.

If you set the bumper zone too low then any contact with a moving bot would more than likely result in the tipping of at least one of the bots involved.

Although that would really create options for interesting strategy if G27 was not around.

Just my two cents....

[BBray_T1296]

Also, many bumpers wear over time. You see teams, probably including your own, when the bumpers are fresh and brand new they sit perfectly and look great, but after a regional or two, you look at them and they sag, if you put your hand on them, they seem kind of loose and are not what they once were. Some teams make bumpers really really well and this does not happen, but a large quantity of teams do not [see teams that have to rebuild their bumpers at regional]. with the bumpers 2" off the ground, this sag has clearance before the bumpers are being dragged around. If they were lower, teams with reversible bumper flaps or drape cloths for changing colors may effectively "trip on their own shoe laces" as it were. Yeah, if the bumpers sag they are technically against the rules at that point, but recall that they check your bumpers during initial inspection, but (so long as you don't modify them) you never get the bumpers reinspected, even if one side falls off in one match.
In 2011 we had our bumpers at the lowest point, 2" and we had one of those red skirts that wraps around the blue cloth, to change bumpers, and we had to be super careful to keep that thing velcroed down so we didnt run ourselves over.

[Oblarg]

Originally Posted by BBray_T1296

Also, many bumpers wear over time. You see teams, probably including your own, when the bumpers are fresh and brand new they sit perfectly and look great, but after a regional or two, you look at them and they sag, if you put your hand on them, they seem kind of loose and are not what they once were. Some teams make bumpers really really well and this does not happen, but a large quantity of teams do not [see teams that have to rebuild their bumpers at regional]. with the bumpers 2" off the ground, this sag has clearance before the bumpers are being dragged around. If they were lower, teams with reversible bumper flaps or drape cloths for changing colors may effectively "trip on their own shoe laces" as it were. Yeah, if the bumpers sag they are technically against the rules at that point, but recall that they check your bumpers during initial inspection, but (so long as you don't modify them) you never get the bumpers reinspected, even if one side falls off in one match.
In 2011 we had our bumpers at the lowest point, 2" and we had one of those red skirts that wraps around the blue cloth, to change bumpers, and we had to be super careful to keep that thing velcroed down so we didnt run ourselves over.

No matter how well you make your bumpers, unless you have a source for ridiculously sturdy pool noodles (if you do, please share it) they will take significant damage if you drive aggressively. That foam can only take so many collisions before the compression becomes permanent.

[Nemo]

Interesting thought. I could see doing a 1"-9" bumper zone for a game with a flat field. For a game with a non-flat field (and possible incentives for bigger wheels), I think 2-10" has worked out well enough.

[EricH]

That's my thought too--non-flat fields require bumpers to be placed higher for design purposes; Aerial Assist was the first game with a truly flat field since 2007 (robot ramps not included) or 2002. All the games in between had something that would make you want higher bumpers or larger wheels if you could get away with it. Ramps, steps, bumps, carpet-covered plates in the field, you get the idea.

But, if you place the bumpers too high, you get a case of high hits/easier tipping (longer lever arm). Too low, and you hit those obstacles or the bumper isn't an obstacle to tipping, you just tip over the bumper.


I think it's best in the general area of where it is. High enough to clear obstacles, low enough to help keep the robot upright and not drag.

[BBray_T1296]

Originally Posted by Oblarg

No matter how well you make your bumpers, unless you have a source for ridiculously sturdy pool noodles (if you do, please share it) they will take significant damage if you drive aggressively. That foam can only take so many collisions before the compression becomes permanent.

I am pretty sure that all of our bumpers now feature pool noodles that are cracked in half along the vertical diametral plane

[Oblarg]

Originally Posted by BBray_T1296

I am pretty sure that all of our bumpers now feature pool noodles that are cracked in half along the vertical diametral plane

Our first set of pool noodles this past season was exceptionally flimsy for some reason. After our first regional, the ones on our front bumper were permanently compressed to about an inch thick.

The frame behind that bumper, incidentally, also developed some surprising curvature (we eventually had to swap it out with another, steel-reinforced piece).

[Lil' Lavery]

Originally Posted by EricH

That's my thought too--non-flat fields require bumpers to be placed higher for design purposes; Aerial Assist was the first game with a truly flat field since 2007 (robot ramps not included) or 2002.

*2009

[Oblarg]

Originally Posted by Lil' Lavery

*2009

2008, too. There was a big barrier in the middle of the field, but the actual driving surface was completely flat with no obstructions.

[BrendanB]

Originally Posted by Oblarg

2008, too. There was a big barrier in the middle of the field, but the actual driving surface was completely flat with no obstructions.

Games like 2008, 2011, & 2013 were technically on flat fields but around the bases of the 2008 wall, 2011 minibot poles, & 2013 pyramids they were raised up close to half an inch due to the field elements below the carpet.

[EricH]

Originally Posted by Lil' Lavery

*2009

Not going from the regolith to the carpet. And even the regolith could deform a bit, going into the carpet that was under it.

I draw a distinction between "flat" and "truly flat" for a reason. A "flat" field includes 2005, 2007*, 2008, 2009, 2011, and 2013; every single one of those had plates under the floor to support something, which affected the flatness (Exception: the loading zones in 2005, which were above the carpet), or a transition from one surface to another (2009). 2007 also had ramps, though those were on robots. Those shallow transitions MUST be accounted for when designing ground clearance, or you'll get slowed down/stopped. (I remember someone at AZ 2010 was a little annoyed at the transition plates next to the bumps--they'd been mentioned in the Manual all along.)

A "truly flat" field does not have those plates underneath or other irregularities, just floor, tape, and robots. 2002 and 2014 are both in that category; 2009 is not because of the regolith/carpet transition.

*This one is on a technicality--the floor base for the Rack was in a place no robot could be expected to come even close to it. But the robot-mounted ramps tip it to just flat, or even out of that altogether.

[Chris is me]

Originally Posted by EricH

Not going from the regolith to the carpet. And even the regolith could deform a bit, going into the carpet that was under it.

Every field has tape on it, so therefore it's not flat, right?

The regolith was no more than 1/8" thick. At this point saying a field with a 1/8" depression "isn't flat" is just being pedantic. The miscellaneous hardware and debris that people build ground clearance into drivetrains in order to avoid is generally more than 1/8" tall. You would have to try very, very hard to design a drivetrain that would be issue free on a "truly flat" field that wouldn't work on a 2009 field (ignoring the wheel rules). 2009 is flat.