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Unread 15-03-2011, 21:21
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Re: Team Update #18

The only issue in Wisconsin that I am aware of occurred when a minibot just touched the plate but did not move it. The Head Ref did a valiant effort to make the determination and double and triple check the rules. At first it was called a climb but was eventually called as a non contact when they removed the minibot and the plate did not move.
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Unread 15-03-2011, 21:22
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Re: Team Update #18

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Originally Posted by Cory View Post
I could do the math for a 2.5 lb object moving 10 ft/s hitting that plate and you'd see it's more than 3-4 N, but if the plate is being violently slammed into the top plate such that you can hear it from the stands, I'd say it's a pretty safe bet they were triggered. Additionally we have 4 official towers and I can confirm that every single time ours goes up the pole it depresses the limit switches, but twice this weekend it did not show the tower as triggered at San Diego.

It seems pretty clear there are still problems with the field and I don't just say this because the tower failed to trigger with our minibot. It was a very common occurrence.
And the naked king had beautiful clothing..."Week 2 results indicated that this change was successful."
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Unread 15-03-2011, 21:24
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Re: Team Update #18

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Originally Posted by Cory View Post
I could do the math for a 2.5 lb object moving 10 ft/s hitting that plate and you'd see it's more than 3-4 N, but if the plate is being violently slammed into the top plate such that you can hear it from the stands, I'd say it's a pretty safe bet they were triggered. Additionally we have 4 official towers and I can confirm that every single time ours goes up the pole it depresses the limit switches, but twice this weekend it did not show the tower as triggered at San Diego.

It seems pretty clear there are still problems with the field and I don't just say this because the tower failed to trigger with our minibot. It was a very common occurrence.
The reason I ask is because one must takes into account that some (in some cases a lot) of that force is deflected and not transferred towards moving the plate. Many of the minibots strike the plate such that they change orientation rather than push the plate.

Hence my question if you knew that the force was being applied (and applied properly) or if it was just a 'gut feeling'. Sound of the impact does not equate into actual applied force.
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Unread 15-03-2011, 21:25
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Re: Team Update #18

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Originally Posted by Daniel_LaFleur View Post
Do you have proof that enough force was exerted? or is this just your 'gut feeling'?
Although I wasn't there, I am certain he has more than a "gut feeling" of assurance that more than 3-4 newtons were applied... HS level physics state that:

mass*velocity(change) = Force*time

Our minibot weighs 2.3 pounds --> ~1 kg
Our minibot travels up the pole in about 1.3 seconds --> ~2 m/s

By just saying that the minibot stops (although ours certainly is repelled backwards, too!) you get a change in velocity of ~2 m/s.

If the minibot is being slowed by the tower for less than half a second (I can't imagine one taking that long... most stop suddenly!), then the Force is greater than 4 Newtons.

(1kg*2m/s) / .5s = 4 N


I certainly hope that refs are allowed to add judgment to obvious false negatives!
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Unread 15-03-2011, 21:31
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Re: Team Update #18

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Originally Posted by Nathan Streeter View Post
I certainly hope that refs are allowed to add judgment to obvious false negatives!
If your minibot hits the plate and triggers: Score

If your minibot hits and doesn't trigger: no score even if visually witnessed by refs.

If the tower is bumped and triggered by a robot: no score/score corrected

I was a ref in Pittsburgh when this rules was changed/reinforced.

Last edited by A_Reed : 15-03-2011 at 21:39.
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Unread 15-03-2011, 21:36
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Re: Team Update #18

One of the biggest issues I see with this whole thing is that most teams don't have ready access to a real tower. They'll just have to hope that their minibot triggers it. They can't really be proactive about a solution despite the warning in the update. I predict that despite this update, there will be almost just as many tower failures next week as in the past two.*

*Provided the towers are not fixed. Fingers crossed!
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Unread 15-03-2011, 21:36
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Re: Team Update #18

Quote:
Originally Posted by A_Reed View Post
If your minibot hits the plate and triggers: Score

If your minibot hits and doesn't trigger: no score even if visually witnessed by refs.

If the tower is bumped and triggered by a robot: no score/score corrected.
What is your basis for this statement?
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Unread 15-03-2011, 21:37
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Re: Team Update #18

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Originally Posted by AdamHeard View Post
What is your basis for this statement?
Team Update 18 and listed in the manual from a team updated around 15 or 16 because of how at week zero events robots acidentally triggered the plates.
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Unread 15-03-2011, 21:39
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Re: Team Update #18

Quote:
Originally Posted by AdamHeard View Post
What is your basis for this statement?
Instance 1: common knowledge
Instance 3: been proven by previous events
Instance 2: proven by Update 18
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Unread 15-03-2011, 21:57
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Re: Team Update #18

Note the second paragraph of the Update. If you hit the trigger plate directly on a bolt, it will not register. Fix your Minibot so it hits inside the bolt-pattern circle.

It should work - it did work in the vast majority of instances in Week 2. If it doesn't work, the ref and FTA can determine if the trigger is working properly.
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Unread 15-03-2011, 22:05
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Re: Team Update #18

It says, "we will be relying on the automated scoring of the minibots". Does this mean that there will be no referee calls at all?
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Unread 15-03-2011, 22:16
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Re: Team Update #18

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Originally Posted by BrendanB View Post
It says, "we will be relying on the automated scoring of the minibots". Does this mean that there will be no referee calls at all?
Or at the very least, less than previous weeks. Technically, the manual does say that if the plate does not trigger it, it goes not count.
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Unread 15-03-2011, 22:28
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Re: Team Update #18

Being at both a Week 1 event (Kettering) and a Week 2 event (Waterford) I can agree the changes had a night and day difference. At Kettering, hardly any of the towers registered. The slower minibots that creeped up the pole would generally register, but teams such as 27, 33, 67, and 2337's minibots would register rarely, if at all. But in Week 2, comparatively faster and slower minibots were triggering the towers with no issue at all (the only tower-related issue I saw was lights not coming on at all, but it still registered with the FMS).

The update definitely keeps a layer of uncertainty with "What if there's an error on Einstein?", but the changes seem to be working so far. That worry can be revived if we continue to see errors into weeks 3 or 4, but for now, awesome solution. From what I've seen, it works like a charm.
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Unread 15-03-2011, 22:31
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Re: Team Update #18

The rules stated minibots need to exert 2-4 N of force to register. Teams should have designed their minibots to exert at a minimum 4 N force.

All this update is saying is if teams have not designed their minibot to this spec, they will not trigger the tower in week 3, and if they have, the minibot will trigger the tower.

Perhaps FIRST has figured out a way to make the towers accurately sensitive to 2-4 N force. If after week 3, your minibot registered half the time and didn't register the other half, AND you have physically measured the force with which it hits the top plate to be >4N, then there is a case to be made.

As for right now, they are just rectifying a lapse in the rules that has been bypassed (in good faith and fairness) by the referees in weeks 1 and 2 for what they thought to be a field error.

All we can do is play by the rules.

Last Note: I don't think the vertical force problem is as simple as some of you are making it out to be. Remember 2 years ago in lunacy, there were hundreds of posts about how "it won't matter how many wheels are touching the floor because frictional force is not area dependent." In fact, it certainly was area dependent because of surface roughness- a fact that many teams overlooked. I remember team 2753 (a rookie) realized they had better traction with more wheels despite the simple physics, and made it all the way to Einstein because they had better acceleration and speed than anyone else.

In the minibot case, there are motors which stop turning when the light switch is triggered, there is rolling friction, some other parts dragging on the pole, the light switches absorb some of the force in being depressed, etc. All of these things could add up to a difference maker. And no, I have not attempted to calculate it either, but that's why if you think something is fishy about the system, you need to physically measure the force out on the practice field.

A rare 2 cents from my short arms and deep pockets...
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Unread 15-03-2011, 22:50
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Re: Team Update #18

I can see this rule being needed as we approach the Championship and many teams will have minibots, but I'd love to see the computer's results only being used when it's too close to call.

Assuming they can get the sensors to work properly this is a great change. However, from experience with Breakaway's automated scoring system, there will be many bugs which will cause teams to lose matches.

The field techs and refs have there work cut out...
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