pic: New low bar flaps
 

Re: pic: New low bar flaps
 

Is there no aluminum bar anymore? That might mess with a few robots going under.

Re: pic: New low bar flaps
 

Do they easily spin around the bar? From my point of view our design criteria of 14" just got cut shorter...

Re: pic: New low bar flaps
 

They seem to flip around the bar pretty easy.

Re: pic: New low bar flaps
 

This looks terrible. I thought FIRST was concerned about the aesthetics of the field this year?

Has anyone tried bowling a ball through the flaps yet?

Re: pic: New low bar flaps
 

I have a question that might be silly, but I may have missed something big. I admit I can't read every thread on CD (Sorry I'm slacking...)

Why is FIRST changing the low bar flap?

Re: pic: New low bar flaps
 

In week 1 the low bar flaps were shredded by teams at pretty much every event. Some events made new flaps out of bumper fabric (MUCH more durable), others ran without them entirely. This new design was FIRST's solution for week 2'

Re: pic: New low bar flaps
 

I'll assume you've been busy the last week. The cloth from the original flap was somewhat flimsy and easily torn by robots. Apparently by robots you wouldn't think would poke holes and tear through the flaps. The GDC came up with this solution instead of trying tougher cloth for the original style of flaps. This decision has been somewhat controversial.

Re: pic: New low bar flaps
 

Part of the reason is that they needed to send the right amount of material to 24 DIFFERENT events on less than one week's notice. They were able to source something that works from McMaster Carr, a company uniquely adapted to filling this kind of panic induced rapid shipment of something.

TL;DR I ordered a roll from McMaster last night at about 5:30pm an I had it in my grimy hands by 9:30am this morning. That's a 16 hour from ordered to delivered 500 miles away.

Re: pic: New low bar flaps
 

Plus it needed to be able to be implemented in the field with items in case 8, so your basic hand tools, a drill, zip ties, and gaff tape.

That is the reason that any sort of cloth which would require a sewing machine was ruled out, in my opinion.

Re: pic: New low bar flaps
 

/snicker. I never really considered McM-C business model to be "we have everything and when you are in a frenzy we can have it to you in 12 hours" but it seems to work.

I'm not sure that I would have put the zip ties on the top, that looks like a snag magnet. If they get snapped off they can learn and not put them back on the flaps.

Re: pic: New low bar flaps
 

I missed this update.

What are they actually made of?

Looks a lot like ABS sheet that I've used on so many robots. In 0.020" thickness it comes in rolls and it's pretty cheap ($2 per ft for 6" wide strips)

Dr. Joe J.

Re: pic: New low bar flaps
 

It's vinyl sheet. The changes were detailed in the most recent team update: https://firstfrc.blob.core.windows.n...Updates/15.pdf

It can be found/purchased here: http://www.mcmaster.com/#1894a214/=11hewcj

Re: pic: New low bar flaps
 

I did the same thing. Now I have a roll of this stuff to redo our practice bar with. It cost around $45 for the roll as I recall. plus some shipping.
We get that same kind of service from MC up here in Washington too.
In fact most of the time I order parts from MC we get them the next day even without asking for express shipping.

Re: pic: New low bar flaps
 

Why did they remove the lower bar. Many teams designed there robot so that the bar would slide over there robot. Without that is could cause a major entanglement issue

Re: pic: New low bar flaps
 

This is a joke. The bar is an entirely different obstacle now. Shouldn't have rolled this out till next week so teams had time to prepare...

Re: pic: New low bar flaps
 

Seeing as FIRST basically had no low bar flaps left after week 1, no matter what they did it would have been "an entirely different obstacle". This seems like the closest they could get to the former behavior on their tight schedule.

Re: pic: New low bar flaps
 

That's definitely not the most attractive solution I've seen to a problem. How fast and easily do they get pushed sideways and get hung up on the zip ties on the bar?

Re: pic: New low bar flaps
 

Unless something changes in the morning, Kansas City was still using regular low bar coverings, except they are made from red and blue bumper material.

Re: pic: New low bar flaps
 

Oh boy, now we have drastic inconsistencies across events!

Hopefully Kansas City switches to the new method for the actual matches.

Re: pic: New low bar flaps
 

Not so much the flaps themselves, but the zipties at the top (around the low bar itself, holding them in place), get pushed out of place at least every two matches.

Everyone that I've seen go under the lowbar (so far) has seemingly gone under it the same as they would with the normal flap.

Re: pic: New low bar flaps
 

I know departing from a field element with very little notice is a big change, but I honestly don't see what everyone is so up in arms about.

Sure having multiple flaps hanging inside a robot, when the design was for a solid bar across the top, but these flaps don't look like they are going to pose much of an issue for any robots that I have seen. They look exceptionally slick and very responsive to being pushed aside.

Re: pic: New low bar flaps
 

Just to have some fun and add some input... I have heard of at least one team saying that the flaps cause the ball to come out of their robot.

I know my robot will not be affected by this change at all. (Or I hope so, we'll see in two weeks)

Re: pic: New low bar flaps
 

I think that depends on the robot.
Flaps may cause entanglement vs one big wide fabric.
Also, as Alex mentioned, I could see a design where it could alter the ball placement in certain robots. With one large fabric, teams have already made fabric/portcullis guides that they ride on instead of sections inside their robot.

At Lake Superior last weekend, the sewing machine on the side of the field actively creating a low bar curtain out of bumper fabric was pretty neat to see.

Re: pic: New low bar flaps
 

Apparently KC regional doesn't qualify for "most" events status. I asked Tyler, the head ref, this morning and he pointed out the operative word "most" in the update.

Re: pic: New low bar flaps
 

Get back to me once you've played with them. And even then it's not a change that effects everyone. But it does effect some people because robots were designed for a specific fabric. As a collective FIRST did not give teams ample time to adjust so some teams are being penalized. They should have just played without the fabric this week and installed the flaps next week.

Re: pic: New low bar flaps
 

It's also due to shipments. The places close to carr warehouses and all will get them first than others.

Re: pic: New low bar flaps
 

Has anyone actively tried to get a boulder through this? I know it's "technically" illegal but if someone can get the ball through the gaps after they've potentially been disrupted and moved by a robot isn't that more of just a poor design by the GDC then a foul or illegal movement of a boulder by a team.

Re: pic: New low bar flaps
 

Some of the volunteers at Wilsonville were trying to do this while teams were connecting to the field...they didn't manage to get one all the way through, but one boulder made it to the other side of the low bar, held in place by one of the flaps. Definitely not impossible.

I was also playing around with one of the low bars -- as a result of the rubbery material the flaps are made of, it's close to impossible to get it to swing all the way around the bar as the fabric did. I couldn't tell exactly how much room it was taking up, but I think it was about half an inch under the low bar, so some teams that are close to 14" could have a little unexpected fun this weekend getting through.

Re: pic: New low bar flaps
 

I imagine you have played with them then, if you are continuing the discussion? How have they affected your play?

I am very interested to see real results of the change, but we are all operating on guesses at the moment. You said that it does affect some people, do you know who? I would like to see the implications of this change and you are acting like you already have some knowledge that I don't.

Re: pic: New low bar flaps
 

We aren't all operating on guesses... There are events going on... there was a practice day at multiple regional today....

Re: pic: New low bar flaps
 

It seems the new strips are ziptied to each other, so they all move as one, so it shouldn't be too much of an entanglement problem.

Re: pic: New low bar flaps
 

Unless it's just us, they aren't. There are zipties on either side of the flaps to hold them in place on the bar and then another pair attached to each flap itself so they don't fly off the bar. (Since it's just a piece of the vinyl draped over the bar)

As per flipping them around (not your post, but it's early so I really don't want to go back and quote theirs too!), it hasn't seemed like too much of an issue here in Arkansas. That might not be true today or in other places, but it does appear that the flaps fling outward just so that it lets robots through fairly easily.

Re: pic: New low bar flaps
 

Thanks for sharing the picture!

Hopefully this'll work alright...

Re: pic: New low bar flaps
 

I don't know, using bumper fabric for low bars didn't make the obstacle entirely different, except for the part where bumper fabric was far less prone to ripping apart. If anything buying a few yards of fabric seems easier for most events to do than getting strips of vinyl cut and zip tied together. I really don't get why FIRST went this route.

I'm especially troubled by the early reports that this vinyl makes the low bar effectively shorter. Making the biggest design constraint in this game even tougher, long after we're finished with our robots, instead of "just" buying tougher fabric? For once I'm glad I competed Week 1 and not Week 2!

Re: pic: New low bar flaps
 

FWIW, the material is surprisingly heavy as a curtain, and is just as effective as the previous style of low bar for preventing balls from passing.

Re: pic: New low bar flaps
 

Watching the live feeds, it looks like individual flaps can enter the robot? Can anyone at an event verify this? If true, and if the height has truly been shortened, FIRST has dropped the ball on this one. I can see the need for a remedy but the characteristics need to be identical. This is the best engineers can come up with?

Re: pic: New low bar flaps
 

With McMaster's incredible distribution system the events did not have to obtain the vinyl strips, they were drop shipped, presumably to the organizer of the event. They can be implemented with the tools in Case 8 so that they are identical across all events. The availability of fabric locally may be hit or miss and FIRST probably couldn't find a supplier that could ensure that almost all of the 21 events being played this weekend received it in time. It would also require a sewing machine at the event and it really needs to be a heavier duty unit to stand up to sewing the bumper fabric consistently.

Consistency is a huge part of this and having the field supervisor cut the roll into specific lengths and drill a couple of holes at a specific point is something that should be relatively consistent.

Are you basing the thought that it reduced clearance a statistically significant amount on actual match play reports or what has been postulated here? Ditto for the hypothesis that a human player can bowl the boulder through it. Personally I've only seen speculation about that and not verified proof of either. Yes the 4mm thickness of the freezer door is more than the cloth but it is certainly within FIRST standard of tolerance that teams should have designed around. The freezer door material is quite heavy and semi rigid. With two strips I doubt the mass of the boulder is high enough to break completely through properly positioned flaps unless you've got a really really strong bowler.

For those teams that are complaining that the flaps could damage their camera I have to ask, did you plan for protecting your camera from the missed high goal shot that may land on your robot? For those that the flap causes their ball to be dislodged from its position I have to ask did you design your robot in such a way that the ball is not dislodged from going over the rougher defenses or against rough defense? I have a hard time imaging a situation where the flap sliding across the camera would damage it while a boulder falling from a couple of feet wouldn't. Ditto for dislodging a ball, if a flap can dislodge it what happens when crossing the rock wall, moat, chilli fries or ramparts at speed?

I know for my team I insisted that the camera be located in a manner that it would be protected against a boulder that may land on the robot. Another requirement was that the robot maintain the ball in the ready to shoot position despite an unusually rough defense crossing or a high speed impact. I also insisted that the robot be designed to clear the low bar if for some reason it was 1/2" lower than the dimensions on the official field drawings. So for us I don't see it as an issue but we will find out tomorrow.


For the record our robot was designed with the knowledge that the official fabric was not highly robust. So we tried to minimize any potential damage to the fabric so that we weren't at risk for a penalty for damaging or repeatedly damaging the field.

Re: pic: New low bar flaps
 

Robots have no problem with the new low bar, but I have gotten boulders stuck under the flaps, so they doesn't roll back into the neutral zone like it was designed for. I'm sure human players that can bowl better than me could get the ball through the flaps.

Re: pic: New low bar flaps
 

It's nice that you don't have anything to worry about. We designed our robot with many of these things in mind, but under the assumption that there would be that nice solid bar there. We have these dorsal fins that work perfectly well with the normal low bar, but now we have to worry about them dragging excessively on the vinyl, or worse, slipping into one of those slits that are now there. So it's entirely possible to have a reasonably designed robot that's going to have issues with this significantly different obstacle.

Re: pic: New low bar flaps
 

After two weekends using them on my fields (WPI and UMass Dartmouth) I can say the plastic flaps held up nicely with no rips and only minor scars along the top. Very few zipties popped. Every few matches in my rounds I'd adjust them back to spec -- "evenly spaced" which ends up around a one inch gap between them. There are two holes for two zip ties either side to keep them on, and a ziptie each flap side around the bar to keep them from sliding too much.

There have been a couple of boulders that managed to roll up to the flap and push the flap a little under the bar, but none (that I saw; I can't be everywhere ya know!) ever got thru. If your robot drives thru fast enough one or more flaps swing up and over, or just roll up, which I guess is where the scars on the top come from.

Re: pic: New low bar flaps
 

Yeah, honestly I can't remember hearing about any problems regarding the field at our week 2 event, or anything since. I think the fixes to the low bar and Cheval de Frise are holding up. Not bad! Hope they last another 4 weeks of competitions.

Re: pic: New low bar flaps
 

My bot was designed for the old one, the flaps never messed with our bot even though they came into contact with our electronics. They look like a bigger issue than they were, in my opinion.

Re: pic: New low bar flaps
 

Actually, I am really surprised at the muted response from the Fairness Cult on this point. No matter how you played this your team was impacted by this change. Many teams that designed stuff into their robot that other's didn't have a claim to this being an advantage that the GDC took away from them. Many teams that had perfectly reasonable solutions for the original design have had fits with the new one.

I don't think it is a HUGE deal but I really was expecting a hue and cry from the Fairness Cult corner of the FIRST community.

Am I just getting deaf in my dotage or had the FIRST community matured a little (realizing that FIRST was clearly in the wrong but that they had to do something as not acting was getting more and more impossible as the season progressed)?

Dr. Joe J.

Re: pic: New low bar flaps
 

There were times at UMASS Dartmouth this weekend where there were several balls stuck in these flaps, forcing teams to go around the low bar. They would have to go from the courtyard to the neutral zone before attempting to damage the defense so they could knock these boulders out of the way without being penalized. It was a bit of a hassle to say the least.

Re: pic: New low bar flaps
 

Can confirm that flaps can fall inside robots, we actually had to e-stop our robot on the low bar because of a combination of this and some partial automation. We mistakenly dropped our arm using "intake" instead of just lowering the arm, and a flap falling inside the robot triggered the beam break to make the arm and shooter both unfold up while we were halfway through. Would never have been an issue with the old flap.

As a quick fix, these worked pretty well. The fact that flaps can fall inside seemed to be the biggest functional difference, the new physics did not seem to be to much of an issue for most of the teams, and beyond a habit adjustment we did not need to make major changes. That being said, a robot with similar design but different quirks to the code could have a rough time with this.

Re: pic: New low bar flaps
 

That's why I asked you what your experience was . . .
Like I said, it sounded like you had experience, and I was hoping you wouldn't just keep it to yourself.

Re: pic: New low bar flaps
 

Yes we tried, and the flaps still block balls from going through unless it it shot through at a very high speed. Also, they each rotate separately and are slightly stiffer, therefore basically impossible to wrap around the bar to the point where it starts spooling up.
And if your robot could fit through the old version, it will have no problem fitting under this new version either.