Team Update #18

[Mike Copioli]

Originally Posted by MagiChau

Trigger is listed as the plate being pushed.

TRIGGERED – the act of pushing the bottom disk of the TARGET so that the sensors are tripped and a
signal is sent to the Field Management System (FMS). When a TARGET is TRIGGERED, the
MINIBOT RACE on that TOWER is complete.

So........... were does it state HOW the plate must be pushed? To Seans point, stating that it merely needs to be triggered is ignoring the intent of the rule....To determine the WINNER, AND THE SUCCESSIVE PLACES, of the minibot race.

[MagiChau]

Originally Posted by Mike Copioli

So........... were does it state HOW the plate must be pushed? To Seans point, stating that it merely needs to be triggered is ignoring the intent of the rule....To determine the WINNER, AND THE SUCCESSIVE PLACES, of the minibot race.

Found the rule G46 the minibot may only be used to climb the pole.

<G46> MINIBOTS may only be used to climb the TOWER.
Violation: PENALTY plus YELLOW CARD

[Ether]

Originally Posted by jspatz1

Regarding "the bolts"....it seems that they should have been fixed to the lower plate, and moving through the upper plate, so that they move with the lower plate no matter where it is contacted, rather than being fixed to the top plate and protruding through the bottom plate, so that they create 4 areas which block the minibot from triggering. From my understanding of the drawings, this would be an easy change to make.

This change would probably have unintended consequences. The bottom plate would likely be more susceptible to jamming. The slightest tilt could bind the threaded bolts in the holes in the upper plate.

[jvriezen]

In retrospect, I think a better trigger design would have been to have a stationary aluminum lower target plate, insulated from the pipe, and specify that TRIGGERING requires completing a circuit by connecting the pole to the plate with some electrical conducting material in your MINIBOT. Nothing would need to move, you just have to electrically connect the two. This would have the downside of sidestepping the engineering tradeoffs surrounding speed and weight and time to reverse power, making it a simpler (but more well defined) challenge.

John
FRC Team 2530 "Inconceivable"
Mentor, Inspector, Drive coach

[Chris is me]

Originally Posted by Karthik

Ken's point is a very valid one. Does anyone have any video of Minibots hitting the top target but not triggering the target during week 2? Right now we're just dealing in speculation which isn't leading to anything productive. From what I saw in Pittsburgh, the large majority of minibots were in fact triggering the top target. If this wasn't the case at a regional you were attending, let's try and figure out what the issue was that was causing these false negatives.

358 didn't trigger their pole at WPI despite clearly causing the polycarbonate to deflect. I will try and get our video.

Other than them, few had any problems at WPI

[Tristan Lall]

With respect to the act of triggering, here are some cases based on the way the rule is constructed in the manual:

1. Hit the tower base, tripping the switch: false positive
2. Push on the plate, tripping the switch and causing FMS to register it: true positive¹
3. Push on the plate, tripping the switch only momentarily (but long enough to send a signal), and the FMS misses or ignores it: false negative²
4. Push on the plate, tripping the switch and causing FMS to receive the signal, but a bug prevents the FMS from registering it: false negative³
5. Push on the plate with 100 N, bending it visibly, causing the tower to sway, emitting magic smoke, but failing to trip the switch: true negative⁴
6. Minibot reaches the height of the plate, but FMS doesn't register it, so referee grants it: educated guess (could be either true positive of false positive, but the ref didn't have anything to do with that fact)

Some of these are quite perverse. I've left out field faults, but in some of the above situations, they're an additional complication that can perhaps restore some equity, if identified properly. (If replaying the match suits you.) I've also left out GDC intent—because although the high-level intent is clear, they have offered no substantial guidance about the actual sequence of events they had in mind for triggering the tower.

If you think this is crazy, don't blame me. I didn't design the game that way.

¹ Which won't count toward the race if it wasn't the minibot doing the pressing!
² The rules have no provision for a minimum duration. If the switch is tripped, an ideal system would not wait.
³ It's basically impossible to identify this false negative if the FMS doesn't throw an error code or something.
⁴ The force isn't part of the determination of triggering. And since sending the FMS a signal is an integral part of the act of triggering, if the sensor doesn't work right, you didn't trigger it. Doesn't that suck?

[Mike Copioli]

=MagiChau;1040834]Found the rule G46 the minibot may only be used to climb the pole.

You missed the point.

Besides this states nothing about HOW the PLATE gets pushed only about what may climb the pole. There are many forces that can 'PUSH' the plate without actually climbing the pole or even contacting the plate at all.

In case you have not figured out my point, I will clarify: To differentiate between TRIGGERING first and WINNING the race is lawyering the rules as the obvious intent is to determine who is first, second, third and fourth and assign a point value to represent each place.

If we lose a match because the other alliance scored more points than us. I can accept that and applaud the victors.

If we lose a match because our alliance partner goes into the opposing alliances scoring zone contacting a robot incurring a red card. I can accept that and commend the refs for making the correct call.

But if we lose a match because the field did not operate as intended or described in the user manual as interpreted by the TEAMS, FIRSTs customers, using a minibot that was built to operate under said parameters....This I cannot accept and will not accept and will result in a student standing in the little ? box at the end of the match every time it happens.

If TRIGGERING requires some amount of debounce time to register, or something greater than 4 Newtons, or Coke turning into Pepsi, this should be CLEARLY published in one of the many user manuals put out by FIRST.

[MagiChau]

Only the minibot is allowed to trigger the plate and be awraded points and the minibot is only allowed to climb the pole so only the minibot is allowed to climb the pole to trigger the plate and scores points according to the race's results. Is this not the intent of the rule and the wording of it? Why can a flawed field not be accepted as possibly existing? Week one after all usually has delays from fixing some electronic errors. I, myself, got frustrated in week 1 trying to fix why the robot sat still for 2 qualification matches when the drive-team reports they have communication, we already tested in the pits, and it was working earlier.

Humans only have so much insight before forgetting something. The GDC might have thought saying 4N of force acting on the trigger plate was enough but apparently it did not happen so. I cannot say anything on what they should have or should not done.

[Ether]

Originally Posted by Chris Hibner

...bind on the pole like I've seen the plate do.

Using the nominal dimensions on the field drawings for the pole OD, the threaded bolts, and the hole diameters and location in the polycarbonate plate, plus the apparent location of the sensors, it appears that if the plate is lifted off-center so that it pivots on the bolts it will reach an interference condition with the bolt threads and the pole before it travels 1/4" at the switch. FWIW.

[Grim Tuesday]

Simple solution: Use camera backup, officaly fed into the field system, and read post match by a scoring personel. You could set cameras up on top of the alliance station walls, or pretty much anywhere as long as they have a clear field of view.

[boomergeek]

At week 1, with one sample, "force of 2-4N" was a complete rule.

If an X sampling time requirement is added to a trigger event and not reflected in a rule update: then FIRST is not being completely open and honest.

Some teams will end up with more access to more information than other teams.
I didn't know sampling was added. All that was officially reported was it was being fixed to prevent false triggers from robot collisions.

Some teams found out some of the sampling changes- was any of the that information given outside the Q&A?
(I could not find any discussion of sampling on FIRST Q&A)

[colt527]

[EDIT] Originally referenced a post later removed by author later, so I wont quote that, but I still think a post about attitude is generally relevant, so I will leave the rest even though it is now somewhat out of context.

I understand the frustration of losing a match because of something that you think is out of your control. Back when I was driving in HS, I felt the same way. As a volunteer, I can tell you it gets pretty old pretty fast to have teams getting in your face and giving you an attitude about these types of issues. I know it sucks to lose matches, but please remember the greater purpose we are here for and how negative attitudes affect that.

So even if you can prove that something unfair happened, please lets all keep a calm and professional composure and remember our true greater purpose here. Let's debate issues, but in a civil and professional manner. I am not saying that this conversation has turned into this, but what type of example is being set for the students if after a match the minibot doesn't trigger and you start complaining about FIRST and the field staff to your students.

[Schnabel]

Originally Posted by techalex

The triggers are designed with multiple sensors, and the FMS only looks for 1 of those to be triggered for any amount of time. Thus making the minimal amount of force still trip the tower. The towers have been tested and proved to be much more accurate since week 1, so I think this should be a non-issue now at week 3.

NO IT DOES NOT. From looking at the way that these are designed at the Kettering District, there are 3 trigger switches, they are connected in series!

Graphical Representation:

___________ (Power in)
.................|
................[ ] (Sensor 1)
.................|
................[ ] (Sensor 2)
.................|
................[ ] (Sensor 3)
.................|
__________| (Reading out)

This means that all three switches must activate in order to trigger the tower. What I noticed with most of the fast minibots is that they actually hit the plate so hard that it wouldn't go up horizontally, thus not triggering all three sensors. We did have one minibot that I loved that was the slowest one there (wish I knew what team it was), BUT because it took more time to make it to the top it triggered the tower every time. Just for reference it came down as soon as it hit, just it did both in a slower manner than say 33's or 51's which were super fast.

Also another note for the fast minibots. When you go up so fast that you hit the plat and skew it from horizontal you actually bind it against the threads of the bolts holding it together. This means the plate won't move past a certain point, which just may be before the trigger point.

[colt527]

Originally Posted by Schnabel

NO IT DOES NOT. From looking at the way that these are designed at the Kettering District, there are 3 trigger switches, they are connected in series!

They look like they are in series, but I believe they act in parallel. Check out attachment. I helped make the tower mods and this is how I remember it working.

If any of the contacts are closed, the whole switch is closed.

Please correct if wrong.

[Vikesrock]

Originally Posted by Schnabel

NO IT DOES NOT. From looking at the way that these are designed at the Kettering District, there are 3 trigger switches, they are connected in series!

Two things here:

1. The GDC has said in the Q&A that only one switch needed to be triggered. If they were wired in series they must have been wired normally closed.

2. This is somewhat irrelevant as the microswitches were replaced in the Week 2 retrofit kit for the towers.