Structural Integrity of Competition Defenses?
 

Ever since Kickoff, I've had a lingering fear that a robot could accidentally break a defense. I haven't gotten a chance to go to a competition or even see a livestream this year so I'm not familiar with how the game is generally being played yet. I've heard nothing so far, but it's only the end of Week 1 (unless I'm wrong and a defense DID break at some point?). Theoretically, if something happened and a robot flies into a defense at full speed, what are the chances that a defense could break and what would happen to the match as a direct result if something DID break?

Re: Structural Integrity of Competition Defenses?
 

At Granite State, the Low Bar fabric was ripped so many times that they ran out of backup fabric, and there were no fabric stores open nearby. So the fabric ended up being removed on both low bars, and human players were instructed not to bowl hard enough to send boulders into the opposing courtyard.
So yes, the low bar fabric was broken, and that temporary human player rule change was brought into effect.

Re: Structural Integrity of Competition Defenses?
 

At Kettering District #1, the low bar fabric was torn to the point that they removed it from both bars with about 5 qualification matches left. The fabric was absent from the elimination matches. Human players were told to not bowl through the low bar. The sally port cover sheet also took some damage from teams running into it. The zip ties would break very often and the whole panel fell off the defense at least one time. The damage on the sally port didn't affect any matches or the event to my knowledge.

Re: Structural Integrity of Competition Defenses?
 

At Southfield, one drawbridge split in two through normal game play, the rough terrain platform got bent, and I assume some other defenses got damaged, but this is what I saw personally. Also, during the playoffs, the stone decorative lexan on the sally door got broken off.

Re: Structural Integrity of Competition Defenses?
 

In Duluth, we had the same low bar fabric issues as everyone else, but making replacements out of bumper fabric worked perfectly fine after we got them on the field. We had one drawbridge break - the lexan broke clean off at the base, and didn't even slow the robot down. Other than a few busted zip ties, that was really about it!

Re: Structural Integrity of Competition Defenses?
 

I mentioned this in another thread but in the first day at Guildford county, our curtains ripped. The amazing NC crew made two curtains completely out of duck tape. It had no issues but did act a little differently than the original curtains

Re: Structural Integrity of Competition Defenses?
 

At Toronto Central, our robot got entangled in the low bar fabric and we were disabled during Q22. The fabric panels on both low bars were removed after that. The match was replayed at the end of the day and the fabric had been replaced with red bumper fabric which seemed to hold out OK for the rest of the game.

I saw Koko Ed post in another thread that one of the portcullis defenses was shattered due to a robot repeatedly ramming it trying to get through.

The cheval de frise seemed to hold up well in ours, presumably after the modifications discovered in Week 0.5.

Re: Structural Integrity of Competition Defenses?
 

At Greater Toronto Central, the welds on the low bar cracked. The bar was held then together with U bolts and wood spacers attached to the polycarbonate sidewalls.

Re: Structural Integrity of Competition Defenses?
 

The pins holding the defenses in at Hatboro were regularly snapped and the defenses were pushed out of place. Low bar fabric was also destroyed a couple of times. Several other defenses had various damage. The field elements really cannot withstand the force of the robots this year.

Re: Structural Integrity of Competition Defenses?
 

Has there ever been a year where there have been this many field elements, and/or where they have this much contact with robots?

Re: Structural Integrity of Competition Defenses?
 

No. Add in the fact they are designed to be removed for different configurations is not helping.

I am really concerned for district championships. It will be very interesting to see what these defenses look like after 6 weeks of events.

One way teams can help is to not run full speed autonomous routines into the draw bridge, sally port, cdf, portcullis, and low bar.

Re: Structural Integrity of Competition Defenses?
 

And that's exactly what I was worried about. As someone who is not in a mechanical subgroup, that was the first thing that came to mind... Mostly because the components used in the defenses looked really flimsy. Just watching a video of a match and seeing a robot pull the drawbridge down makes me cringe. It's so flimsy...

I dunno, the closest I come to working with bend-related issues is the bend radius on our wires :D

Re: Structural Integrity of Competition Defenses?
 

The actual drawbridge material is very resistant to breaking (Lexan) you can bend it at 180 degree angle and it still wouldn't crack. The reason they have fallen apart is because of the harsh angle on the hinge causing the lexan to break free.

Re: Structural Integrity of Competition Defenses?
 

Did anyone get penalized for damaging a field component per rule G12?

Our robot was responsible for destroying a low bar flap at Waterbury. I'm not sure if we were penalized, but we were stuck/ entangled for about 30 seconds

Re: Structural Integrity of Competition Defenses?
 

While competing at the San Diego regional our robot bent one of the defenses accidentally and almost got disqualified because of it. Like others have said before the low bar's fabric also got beat up. All they did was tape it together and as a result the tape got stuck on robots my team's included.

Re: Structural Integrity of Competition Defenses?
 

No it didn't.

Re: Structural Integrity of Competition Defenses?
 

I remember at Northern Lights the portcullis being sent up so hard that a bar that I didn't even know was there came onto the field.

Re: Structural Integrity of Competition Defenses?
 

Did it not split? or was it beyond normal gameplay. If it was beyond normal gameplay, what causes it to break?

Re: Structural Integrity of Competition Defenses?
 

There is a bar zip tied onto the top bar of the portcullis to weigh it down and offset the strength of the springs.

Re: Structural Integrity of Competition Defenses?
 

https://youtu.be/_lu2J4Cp7dU?t=1m16s

Is that not normal gameplay? Or is the word split what is wrong?

Re: Structural Integrity of Competition Defenses?
 

That's not entirely accurate-- here's a couple of pictures from the break at Northern Lights. As you can see, it's very clearly a break-- not the polycarbonate 'breaking free.'

Edit: I had the wrong context when I responded to this, and I don't think this is highly relevant to the post I quoted. It is relevant to the general discussion of defense durability though so I'm leaving it here.

Re: Structural Integrity of Competition Defenses?
 

Speaking of Duluth (while apologizing for going off-topic for a moment)...

Congratulations, Woodie Flowers Finalist. If your nomination didn't mention all of the support you also provide here on CD, it should have.

Re: Structural Integrity of Competition Defenses?
 

A split implies the lexan actually cracked. What you are seeing is the drawbridge acting as designed. I'm pretty sure having teams deal with the two pieces of lexan was not an intentional added challenge, it's just how the drawbridge is designed.

Re: Structural Integrity of Competition Defenses?
 

Based on what I've seen so far, aside from the low bar flaps being torn up and the cheval de frise at Palmetto, the major structures are generally not prone to severe damage. There are lot of scuffs of course and they become dislodged, resulting in match halts or complete match replays. These field elements are remarkably durable considering the amount of force and sharp edges they regularly endure. At Waterbury, there was a robot that accidentally hung from the high goal (yes, I know, a foul and doesn't count as scaling). The tower didn't seem to be any worse for wear from it.

Re: Structural Integrity of Competition Defenses?
 

At the Greater Toronto central regional, the sally port lost the lexan on on the supports several times. That defense really got torn up. It will be interesting to see the state of the defenses in the later regionals.

Re: Structural Integrity of Competition Defenses?
 

In Waterbury we started seeing problems with the pegboard s-hooks that we were told to use, due to the tight clearance of the drilled holes for the pins designated for that purpose, aka they wouldn't push in. We saw it mostly on the Rock wall, then more on the other defenses after they were switched into a spot vacated by the Rock wall. Those robots that didn't adjust their designs to accommodate the rock wall height were the ones that slammed up & over. Most others with Pneumatic tires flowed over. There was a lot of force generated to cause the damages. Except for the mounting design, I thought the defenses were built fairly well. By Sunday morning we had destroyed all the s-hooks & switched back to the pins, which now fit (loosely) into the holes. Now the rock wall started jumping up. We finally gaff-taped across the front/back of the defense to the floor mount & that worked. This is not a solution, just a band-aid.
The low goal curtain was damaged many time & we taped them back together. We got more curtains made up from the school sewing class with a slightly smoother material & they lasted longer.
I have a few suggestions to correct the problems with defenses lifting up, but there is not enough down time or personnel in between weekends to fix them. Obviously this is occurring throughout competitions & I hope they come up with a solution