Leaning Tower of Totes

[JesseK]

At our offseason event this weekend, one of the matches ended with a leaning tower of totes. The tower was not touching carpet - only the white platform and the robot it was leaning against. The RC fell off when the tower tipped.

The stack was 4 totes tall, and the 3rd tote (1 = bottom, 4 = top) was touching the robot - obviously supported by the robot to an extent.

The question - are totes 1 and 2, the ones on the bottom, 100% supported by the platform?

We did not score the totes on the bottom, and in reality the 4 points did not change the outcome of the match or the event for the teams. The rationale used for not scoring them was a free-body diagram performed on the bottom two totes given some of the forces acting on the totes to keep them at rest. The totes would not stay at rest if the non-platform resting entity (the robot) were removed. In other words, the tower wouldn't stay leaning if we removed the robot.

Were we correct, or did we err?

[BBray_T1296]

Could you please post a picture or a quick MS paint drawing of the situation?

[Monochron]

Originally Posted by JesseK

We did not score the totes on the bottom, and in reality the 4 points did not change the outcome of the match or the event for the teams. The rationale used for not scoring them was a free-body diagram performed on the bottom two totes given some of the forces acting on the totes to keep them at rest. The totes would not stay at rest if the non-platform resting entity (the robot) were removed. In other words, the tower wouldn't stay leaning if we removed the robot.

Were we correct, or did we err?

I think this is correct. "Supported" does not necessarily mean "force applied directly opposite of gravity". In that case the upper totes were providing support to the lower totes by means of friction. Or perhaps the lip of the lower tote was pushed against the upper tote. Those totes, in turn, are supported by the robot. So it would be inaccurate to say that the bottom totes are supported entirely by other scored totes.

[GeeTwo]

Definitely a non determinable case just given the words in the rules - you have to read the blue boxes and Q&As. While not rules in and of themselves, they are official interpretations of the rules, sort of like judgements in common law; you can't override them except at the same or higher level. That said, for an unofficial off-season event, rules and interpretations can change from what would happen at an official event. I'll provide the answer I would give if I were a judge at an official FRC event (which I'm not!), unless someone presented an overriding Q&A.

The robot was applying a mostly horizontal force, so the weight was completely or nearly completely supported by the platform. As such, you could have scored the entire stack, except for the blue boxes under 3.1.2.3:

Originally Posted by 3.1.2.3, blue box 1 about scoring totes, sentence 2

Generally, scored Gray TOTES would not be “leaning” off of either side, but rather they would be level with the top of the SCORING PLATFORM.

This one weakens the case for scoring totes, for sure, but is not a killer.

Originally Posted by 3.1.2.3, blue box 2, about RCs

When REFEREES are assessing final scores at the end of the MATCH, if it is unclear whether a TOTE, RECYCLING CONTAINER, or LITTER is being even partially supported by a ROBOT, the assumption will be that the ROBOT is supporting it (and thus it does not score). As such, it is highly recommend that DRIVE TEAMS make it very clear that their ROBOTS are not supporting any scored TOTES, RECYCLING CONTAINERS, or LITTER at the end of the MATCH.

This one decides it clearly in favor of not scoring the RC or any of the totes, either. In practice, if the robot were to back away from a stack leaning upon it, the stack would collapse; if the robot were providing support from the carpet, none but possibly the lowest tote would remain on the scoring platform. I'd only count the totes if their top(s) were horizontal (or in the case of haphazardly stacked totes, if their bases were touching the scoring platform or supporting totes at both ends), or there were no reasonable way to remove the robot that would end up with that specific tote off of the scoring platform.

[BBray_T1296]

Originally Posted by 3.1.2.3, blue box 1 about scoring totes, sentence 2

Generally, scored Gray TOTES would not be “leaning” off of either side, but rather they would be level with the top of the SCORING PLATFORM.

Interestingly, at Alamo we scored a 5 stack that was perfectly balanced on the diagonal slope of the scoring platform and wasn't touching the carpet either. Some interesting physics going on there... We fixed it as we set a can on it so it was only like that for a few seconds.

The idea of the rule is that if the robot was instantaneously removed, the stack would remain scored. I think physically contacting the structure is ok, so long as it isn't load bearing. Not sure what the actual ruling was, but our can lifter coasted down on top of a longstanding stack without moving any totes after the buzzer and by my interpretation the stack should have still counted.

[XenObliv]

http://www.chiefdelphi.com/media/photos/42406?The rule is subject to the ref, simply contacting the robot could give the allusion that the robot is supporting the totes. The true way to know for sure would be to move the robot, if the totes don't move then they are supported and if they do they are not supported. Defying the Laws of FRC Physics is possible.
For your situation the specific totes that move, the third and fourth, would be not scored.

[Gregor]

If you had to draw a free-body diagram then the totes were scored.

[KrazyCarl92]

Originally Posted by Gregor

If you had to draw a free-body diagram then the totes were scored.

Originally Posted by 3.1.2.3, blue box 2, about RCs
When REFEREES are assessing final scores at the end of the MATCH, if it is unclear whether a TOTE, RECYCLING CONTAINER, or LITTER is being even partially supported by a ROBOT, the assumption will be that the ROBOT is supporting it (and thus it does not score). As such, it is highly recommend that DRIVE TEAMS make it very clear that their ROBOTS are not supporting any scored TOTES, RECYCLING CONTAINERS, or LITTER at the end of the MATCH.

Gregor, your point seems to conflict with a blue box in the rules.

[PayneTrain]

Originally Posted by KrazyCarl92

Gregor, your point seems to conflict with a blue box in the rules.

*braces for multi-post back-and-forth over slightly humorous moment at an innocent offseason event that does not necessarily impact any one person or organization in any nontrivial way*

or

[EricH]

Originally Posted by Gregor

If you had to draw a free-body diagram then the totes were not scored.

FTFY.


That being said, the general rule used (at least later in the season) tended to be: At or above robot contact is automatically not scored. So 3 and 4, definitely a correct call.

In this case, using the regular-season rules would also guarantee that 1 and 2 were not scored--there's a question. Using OFFSEASON rules, well that's your decision on how to handle that. You could unstack 3 and 4 and see what happens... or not. In this case, I would probably assume that should 3 and 4 suddenly vanish, 1 would hit the carpet or the robot and invalidate itself and 2.