Controlling balls above the bumper

[jgannon]

Did anybody else catch this fascinating Q&A?

http://forums.usfirst.org/showthread.php?t=14216

By extension of this ruling, you can control ball direction with active mechanisms above the bumper (relative to world coordinates) if your robot is upside down (relative to normal configuration). This opens up some interesting strategies for controlling the ball returns and executing collaborative plays within an alliance. Team 67 had great success with an orientation-changing robot in 2005, as did team 16 in 2008. Now that the door is open, will we see something similar this year?

[Matt C]

Thus, a device that is "below" the BUMPERS when the ROBOT is inverted would be considered "above" the BUMPERS in the coordinate frame of the ROBOT. If such a device were used to control the BALL, then it would be a violation of Rule <G45>.

Am I reading this differently? It doesn't appear to say what you think.

[jgannon]

Originally Posted by Matt C

Am I reading this differently? It doesn't appear to say what you think.

Here's the logical inverse of the snippet you posted:

Thus, a device that is "above" the BUMPERS when the ROBOT is inverted would be considered "below" the BUMPERS in the coordinate frame of the ROBOT. If such a device were used to control the BALL, then it would not be a violation of Rule <G45>.

[Vikesrock]

You would still have to avoid CARRYING the ball, but I agree with your interpretation based on the GDCs bizarre response.

[Matt C]

I was interpreting it as the "coordinate frame" flips. That a device "below" (meaning above on a now inverted robot), would be considered as "above" the bumpers and thus not be legal to use to manipulate balls.

Why the heck are they using "" to explain anything I have no idea.

I took the line:

However, it must be noted that the ROBOT rules are defined in reference to the coordinate frame of the ROBOT when it is standing normally on a flat floor.

to mean that if it's standing normally on a flat floor, that is it's defined coordinate frame. So that when the robot flips, so does the coordinate frame assuming that the robot is now standing normally on a flat floor.

Maybe I'm reading too much into it and the refs have to keep a close eye and keep count of how many times a robot has flipped to determine what the "top" and "bottom" of the robot is.

[Vikesrock]

The Q&A post you quoted in your first post seems to imply that the coordinate frame does not flip.

The quoted text suggests that a device that is physically below the bumpers while the robot is inverted would still be considered above the bumpers in the coordinate frame of the robot and thus would incur a penalty under <G45> if used to control the balls direction.

[Locke64]

Originally Posted by Vikesrock

The Q&A post you quoted in your first post seems to imply that the coordinate frame does not flip.

The quoted text suggests that a device that is physically below the bumpers while the robot is inverted would still be considered above the bumpers in the coordinate frame of the robot and thus would incur a penalty under <G45> if used to control the balls direction.

...and a device that is physically above the bumpers while the robot is inverted would still be considered below the bumpers in the coordinate frame of the robot. They're saying down is up and up is down, thus the coordinate plane of the robot has flipped in relation to the field.

So if you're flipped, you can't control balls from under the bumper (because it would be "above" relative to the robot), but (logically) can control them above the bumpers (as long as it doesn't satisfy the definition of POSSESSION).

A very interesting response indeed. Teams building flippable robots may want to consider adapting their mechanism so it can still work while flipped, without POSSESSING the balls. However, they should avoid building a mechanism on both the top and bottom.

[Matt C]

If that is the case, it seems having a robot that can flip probably isn't the best strategy.