with all this ruling on behalf of the GDC I guess we ore not even allowed to pick up moonrocks anymore, because that would increase the normal force. by carrying balls in a hopper you will increase your normal force. Also does that mean a shooter is out since accelerating a ball up will also increase your normal force?:confused:

I think your reading into it too much. The GDC understands that some actions during the normal playing of the game will increase your weight and traction at various points IE Picking up Moon Rocks.

Let me quote <R06> so that we have some reference here.

ROBOTs must use ROVER WHEELS (as supplied in the 2009 Kit Of Parts and/or their
equivalent as provided by the supplying vendor) to provide traction between the ROBOT and
the ARENA. Any number of ROVER WHEELS may be used. The ROVER WHEELS must
be used in a “normal” orientation (i.e. with the tread of the wheel in contact with the ground,
with the axis of rotation parallel to the ground and penetrating the wheel hub). No other
forms of traction devices (wheels, tracks, legs, or other devices intended to provide traction)
are permitted. The surface tread of the ROVER WHEELS may not be modified except
through normal wear-and-tear. Specifically, the addition of cleats, studs, carved treads,
alterations to the wheel profile, high-traction surface treatments, adhesive coatings, abrasive
materials, and/or other attachments are prohibited. The intent of this rule is that the ROVER
WHEELS be used in as close to their “out of the box” condition as possible, to provide the
intended low-friction dynamic performance during the game

This rule says nothing about normal force, gravity, or anything like that. The only time normal force was mentioned (at least so far and to my knowledge) was on Bill’s blog. He discouraged teams from making devices specifically designed for increasing normal force. I’m sure the GDC is reasonable enough to realise that increasing normal force may be a byproduct of certain robot actions and thus would not outlaw them.

I think the concern of the OP probably resulted from reading the answers to these two questions:



Correct. People have asked using the term, but the GDC uses terms like “increased traction”. The rule is NOT “you can’t increase your normal force”, but “you can’t increase your traction”. Devices specifically intended for that purpose have all been outlawed already. Devices that help accomplish a game objective (namely scoring) are apparently not an issue.

Even non-tractive wheels (i.e. within a small percentage of the rover wheels) are allowed for purposes of data gathering only.

could the GDC rule that your maximum wieght be 120lbs, when you are full or moon rocks. for example if we weighed 119lbs, off the field then could we only pick up a certain number of moon rocks so that we would never be more then 120lbs. (not including bumpers and batteries) then a lighter robot say 115lbs could pick up more then the heavier robot? or does the maximum volume deminsions not include the weight of your payload. I am asking this becase of the recent ruling about the net bieng used to hold the orbit balls.:confused:

The response regarding the net dealt specifically with it exceeding the dimensional envelope as a result of it containing orbit balls. It had little to do with the act of storing balls itself.

Unless you decide to make the balls part of your robot, they’re considered field objects, and not robot components.

Other than the fabrication timeframes, the GDC doesn’t normally write unenforceable rules. This one would be difficult at best to enforce, if not outright impossible.

That and the game pieces aren’t robot parts.

I don’t quite understand the big deal about making the robot heavier… while an increased normal force may improve traction, it won’t help accelerating and braking-- if your robot is heavier, it is that much harder to accelerate. I suppose the only advantage is if another robot were to push you, then it would take a larger force to break static friction. I think that the only reason it seems to improve acceleration is that it slows down the motor speed, bringing it below the threshold of breaking static friction (g*u_s). On the other hand, using idler wheels for the purpose of getting robot motion data may waste the weight that it would have driven otherwise… the other wheels must still pull that load.

Hike Danakian, Reseda Regents Robotics (2584)

Increasing robot mass increases the percentage of the robot/trailer system that is applying power to the floor, thereby increasing maximum acceleration and deceleration.

In other words:

F = uN = umg
F = m

The “m” in the top line does not include the mass of the trailer.
The “m” in the second line does

The big deal about making the robot heavier, is that you have to accelerate the mass of the robot AND trailer, but you only have the tractive force of the robot wheels to do it. The higher the percentage of total weight that’s on the robot wheels, the higher your acceleration can be.

Incidentally, the GDC has clarified that “normal” actions such as handling the orbit balls are perfectly legal even though they increase the normal force slightly, while actions intended purely to increase the normal force are illegal.

I think all that FIRST is saying is they don’t want people intentionally trying to gain force or traction. The point of the game is to score points in trailers without much traction, not to figure out how to get more traction so you can score more points.

The maximum VOLUME dimensions do not include the WEIGHT of your payload. :wink:

The ruling with the net occurred because the net could expand beyond the maximum volume dimensions of the robot, not because of any added weight concerns.