TOWER Malfunctions since Week 3
 

Just wanted to make a comment about the TOWERs.

I have noticed 3 separate TOWER malfunctions since Week 3, when FIRST decided that the TOWERS and FMS would be the final say.

Week 4: Waterloo Regional

Semi-final Match 1-2: 2056's robot crashes into the TOWER base, and sends their minibot up, which strikes the top and comes flying off. TOWER TRIGGERED, but lights failed to go on. FMS received the TRIGGER. (This one, I believe to simply be a matter of the TOWER losing electrical connection with the lights due to impact. This TOWER remained broken for Finals 1 and 2.

Week 5: Greater Toronto EAST Regional

Q58: At T-15 seconds, the roadrunner sound plays and the TOWERs begin the endgame sequence (BASE flashing Yellow, Top indicators flashing all 4 lights). At T-10 seconds, when the TOWERs normally switch the BASEs to Alliance colors, and the Top indicators start the chase sequence, the TOWER BASEs switched, but the Top indicators remained flashing all 4 lights. At approximately T-6 seconds, 1075's minibot hit the top of the TOWER, same as it had been all weekend, TOWER did not TRIGGER. At T-0 seconds, the TOWER Top indicators begun the chase sequence. Referees made the call to award the points to 1075's mini.

Week 6: Michigan State Championship

Quarter-final 2-1: 27/245 (red) and 1718 (blue) DEPLOY MINIBOTs. 245 DEPLOYED early, so their TOWER was DISABLED. 27 and 1718's MINIBOTs reached the top close enough together that its difficult to tell who won. 27's MINIBOT did NOT TRIGGER the TOWER. 1718's did. Race was SCORED as 27, 1718, 245(disabled).

Any other interesting TOWER malfunctions?

Re: TOWER Malfunctions since Week 3
 

What my view on this subject is "stuff happens". Simple as that. We can't go back and change the outcomes of a match. Field equipments beak down just like robots. We can go over all the malfunctions of towers, it is a fruitless as going over all the robot malfunctions that dozens of teams have experienced.

Re: TOWER Malfunctions since Week 3
 

What's weird with this is per update 18... If the tower does not tigger it doesn't count... 27 did not trigger the tower... Therefore shouldn't of had counted... As in other regionals where this was upheld...

Re: TOWER Malfunctions since Week 3
 

There were a couple of malfunctions at VCU. The only one 1885 was apart of was during our first Qual match (Q7?), when our minibot deployed, keeled over 6" up the tower, yet somehow the tower still triggered. We didn't get the points since we didn't actually TRIGGER the tower by definition.

Re: TOWER Malfunctions since Week 3
 

The tower did trigger. Even though the lights didnt show it, the FMS system saw it.

Re: TOWER Malfunctions since Week 3
 

@dodar: Are you sure? Based on the way I read the discussion in the Michigan State Championship thread, FMS did NOT pick up 27 at all. I'm inclined to believe this based on the video, and my personal experience with the instance at WAT. (if it had, it would be a case more like what happened in Semi 1-2 at WAT - TOWER lights not illuminated, but other towers still showing correct readout [1114's mini had 4 lights, 2056's had no lights and no chase sequence after impact, 1075's had 2 lights]) 27's TOWER maintained the chase sequence, even after impact.

Re: TOWER Malfunctions since Week 3
 

I am pretty sure I remember hearing Dave say that the FMS system did pick up the hit even though the lights did not. But if a member of 27 could tell us what actually happened, that would be better.

Re: TOWER Malfunctions since Week 3
 

I know thats what happened in Waterloo. The FMS picked up the score (evidenced by 1075's mini only scoring 3rd), but the lights were toasted. Thats not what happened in Michigan though, at least, the failure mode isn't the same. 1718's TOWER showed 4 lights.

Re: TOWER Malfunctions since Week 3
 

I've also seen several cases where a tower TRIGGERedd prior to the minibot hitting it.

Re: TOWER Malfunctions since Week 3
 

We had a match where our alignment device triggered the tower sensor before the minibot deployed. Unfortunately, this was the "4th" minibot which disabled the field and thus our team did not get a chance to deploy that match. It was an interesting ruling in that the "tower" triggered, but since a minibot did not deploy, the team could not be given the points.

Gotta love automated scoring systems. When they work, they work, when they don't... well... were not gonna talk about that, and instead focus on how they almost always sorta kinda most of the time work pretty much as planned (once they have been fixed a couple of times).

Re: TOWER Malfunctions since Week 3
 

Rule T-17 covers "Stuff Happens" as follows:
<T17> If, in the judgment of the Head Referee, an “ARENA fault” occurs that affects either the play or the outcome of the MATCH, the MATCH will be replayed. Example ARENA faults include broken field elements, power failure to a portion of the field, improper activation of the field control system, errors by field personnel, etc.

We have all seen instances where the towers should have triggered, but didn't. As humans we are not perfect, but it's obvious that the tower mechanisms and/or software are not perfect either. It is a shame that Update #18 pretends that they are.

And you know that how?
__________________

Re: TOWER Malfunctions since Week 3
 

That happened a few times at MSC in quals and elims. And it brings up an interesting quandary. Because of the false trigger, the game ends about 5-6 seconds early.

At that point the referees have to huddle and determine whether or not an alliance could have done enough in the 5-6 seconds that should have happened to effect the outcome of the match. (Because this is technically a field fault)

In most cases hanging 1 or 2 tubes that late in the match will not change the outcome (Most matches at MSC had 3-4 logos on the top and middle rows already so your possible points for hanging 1-2 more tubes is low).

If the score was close and the refs thought someone could have scored tubes to change the outcome then we would have replayed the match. Luckily this was not necessary.

Re: TOWER Malfunctions since Week 3
 

I saw a few sensors fail to trigger that probably should have at VCU.

That the sensors don't work all the time is not an issue. While I would have liked to see less failures, we can't expect the field to work 100% of the time. Where I see a problem is FIRST explicitly disallowing referees from overriding the automated scoring system in instances when it clearly did not work correctly. To pretend that the sensors work perfectly ("you must not have hit with enough force," "you must have hit a bolt," "it works when we whack it with a broom so it must be your minibot's fault..." etc) when they obviously do not is, IMO, a bit arrogant.

Re: TOWER Malfunctions since Week 3
 

There were at least three innstances where minibots did not trigger a particular tower at the VA (VCU) regional. I don't have the match numbers on hand, but I will look through the archive of the even later to find which ones they were. It happened to three different teams (at least), 612, 11, and 339 as stated above. In the cases I saw, it was pretty clear that the minibots hit with enough force, did not hit the bolt, and as far as the human eye could tell, looked like they hit the plate for more than 5ms.

Re: TOWER Malfunctions since Week 3
 

At Philly, both 365 and 1403 deployed minibots that failed to trigger the tower (despite a very loud THUD at the top).

Re: TOWER Malfunctions since Week 3
 

Having been through the Palmetto and the Virginia Regionals, I've now seen quite a few instances of "tower failures". These tend to fall into two catagories:
A) False positives that happen when a robot hits the base hard or a deployment mechanism hits the pole hard. Robots with deployment issues often repeatedly ram the tower trying to get their minibots to deploy, sometimes practically knocking the towers over in the process.
B) False negatives that happen when a minibot climbs the tower, hits the plate, but the sensors don't light. Minibots fall into two categories: direct drive bots that are very fast and light; and geared bots that use the stock Tetrix gearboxes and often stock Tetrix wheels and tend to be slower and heavier. After watching two regionals worth of matches, it is my impression (not backed up by supportable data) that all or nearly all false negatives happen to direct drive minibots. I'm sure there may be exceptions, but I'm also pretty sure there is a statistically supportable correlation.

As an engineer, I can understand that designing a sensor assembly that is sensitive enough to eliminate false negatives while also eliminating false positives may not be as easy as it first appears. But, with something as fundamentally important as an automated scoring system for a national competition, the sensors as currently designed don't seem to be fulfilling their design objectives. I'm sure they could have been designed to be more consistent, possibly by using sensor technology other than mechanically actuated limit switches. I'm also sure that they aren't going to be redesigned at this point.

We, as mentors and engineers, are now provided with a "teachable moment" for our students. Nothing in the real world is exact. Material properties, such as the yield strength of Aluminum, are generated statistically from experimental data. If you want to be absolutely positive to prevent a failure, you use allowable stresses which are well below the statistically generated averages.

We have enough observable data of the behavior of the tower sensors to conclude that their triggering threshold is somewhat inconsistent, but which could be statistically characterized if someone took the time to do so. Teams must choose to either use a heavier, slower minibot which triggers the sensor 98% (rough estimate) of the time or to use a lighter, faster minibot which triggers the sensor 70% (rough estimate) of the time. Engineers make these types of decisions everyday when designing things like cars, aircraft, and spacecraft.

We can complain all we want about the behavior of the sensors, just as we can complain all we want about how engineering materials don't break or buckle under the exact same loads every single time. Or we can teach our students how to deal with uncertainty in their design choices, and accept the consequences of those choices. As a mentor, I see my job as showing the kids how to think about the world less like a high school student (Those stupid sensors don't work right! We just got robbed! This isn't fair! Waaaah!) and more like an engineer (Now that we have observed how the sensors behave, let's make an educated choice of how best to use that behavior to make our team most likely to win.)

Todd F.
mentor, Team 2363

Re: TOWER Malfunctions since Week 3
 

I think one other reason was forgotten. I witnessed minibots climb the poles @ CT Regional & strike the stationary plate bolts. We tested the trigger mechanism immediately after the round & found the tower to be working properly. We witnessed this numerous times.(Witnessed by FTA, FTAA & Head Ref with the pole directly in front of us). We all agreed that the minibots had indeed struck the bolts.

Re: TOWER Malfunctions since Week 3
 

We were told in advance of MSC about the bolt issue, but neither Rush's bot nor ours is large enough to hit them.

The frustrating part for me personally is that at Troy, and at States in an earlier qualification match, our minibot hit the top plate with an audible thud. The tower lights did not change, and we were told we did not score.

In that particular elimination match, for some reason, it was ruled differently. I can only speculate that, as someone else suggested, perhaps the FMS system saw the trigger. It was all very confusing.

Re: TOWER Malfunctions since Week 3
 

Since there are published dimensioned drawings of the sensor assembly, I wouldn't consider a non-trigger due to striking a bolt to be a tower malfunction. I would consider it to be a deficiency in the design of the minibot.

Given that the bolts don't move, a properly designed minibot will avoid contact with the sensor plate in an annulus with an inner radius of 4.5 inches and an outer radius of 5.5 inches (assuming fender washers of 1 inch diameter). Otherwise you risk hitting a bolt (or washer).

Todd F.
mentor, FIRST Team 2363, Triple Helix

Re: TOWER Malfunctions since Week 3
 

Watching the webcast on Friday (Thanks to Team 1517, the Lumberjacks), in their second match, the MOE minibot went up the pole twice and struck the plate both times. I assumed this was a deliberate change to the program to ensure no repeat of a field issue as in match #1. I found out later it was not planned, but when the minibot went back to the bottom of the tower the impact reset it. So it climbed and scored a second time.

Not a bad strategy though if you have field issues and a very fast minibot.

Re: TOWER Malfunctions since Week 3
 

Eventhough there is nothing we can do about it, here is the video of the tower malfunction that cost 11's alliance a spot in the finals.

http://www.youtube.com/watch?v=BvUwW...e_gdata_player

Very disappointing to watch. 11 first then 1676 then 25. Final score without malfunction was 92-91. Two regionals of being the 2nd overall Pick. Two regionals of taking the semis to 3 matches. Two straight regionals of very bad luck.

Re: TOWER Malfunctions since Week 3
 

The weird thing was that 25 and 1676 lit up for second and third place, which indicates that the FMS correctly scored 11's tower as first place.

Re: TOWER Malfunctions since Week 3
 

Not only did 1676 and 25 trigger as 2nd place and 3rd place, at the end of the match they were changed to 1st and 2nd place respectively, even though our minibot must have timestamped to display the other towers as 2nd and 3rd.

Re: TOWER Malfunctions since Week 3
 

Also, all the latest revisions of EWCP minibots were not large enough to hit the bolts. Otherwise 1477, 1323, 816 and 2415 would have all reported the same issues.

Re: TOWER Malfunctions since Week 3
 

The video never shows the lights on the top of the tower that we, 25, scored on. (Chris, are you basing your statement on the linked video or something seen on the webcast?) I'm not trying to argue the outcome of the match or debate any rulings, I'm just pointing out what can be seen from the video. What's interesting is that 25 drives past 11's tower on the way back from deploying before 1676 even deploys their minibot, which had registered as second place (3 green lights). That means our minibot was already up the pole and registered as 1st place, since the blue alliance was awarded the 50 bonus points. So we can agree that regardless of how the match was scored, 1676's minibot was the last one up the pole since they were the last to deploy. Had MORT's tower functioned properly and the red alliance awarded a minibot bonus of any amount, it would have come down to the winner of the minibot race between 25 and 11. If 11 came in 2nd, then the score would have been 92-101 in favor of blue. If 11 came in 1st, Akash is correct that the final score would have been 92-91 in favor of red.

It was an extremely close match and truly could have gone either way. 25 wishes 11 nothing but the best of luck in St. Louis, both on the field and competing for the Chairman's Award. MORT has proven themselves as more than worthy contenders this year and has a lot to be proud of. We hope to finally get the opportunity to play on the same side of the field this year, either at the championships or during the off season.

Re: TOWER Malfunctions since Week 3
 

That is interesting. Now that you point it out 25's minibot had to have been first/second. I believe we have a picture of it triggered as third though. I will look.

Re: TOWER Malfunctions since Week 3
 

No photo of the towers but I believe 1676 also has a match video, we can check there. It's fine that we lost but I want to get to the root of the problem with the towers.

As you said, it was a very close match -- congratulations to 25/1676/1522!

Re: TOWER Malfunctions since Week 3
 

Team 2363 also has video of all the matches. As soon as I can get my hands on the SD cards I'll get some up on youtube.

Re: TOWER Malfunctions since Week 3
 

Are you sure that's true? I was a volunteer doing field reset and heard the conversation between five or six Team 11 students and the referees. As an alum of 339 I was interested in the outcome. No one mentioned that 25 and 1676 had registered as second place. Had someone mentioned that, I imagine the head ref would have ruled in red's favor, as that proves that the minibot must have triggered the sensor (although the lights malfunctioned).

I don't really remember now how many lights were on. It doesn't matter now, but I guess this might be a lesson that when things don't work as planned, be as observant as possible to determine what went wrong.