Expanding downward

At TMT in Hilo, Hawaii there was a bot which took the top parking spot and deployed a ramp. We were considering the same device on our bot. Does downward expansion count towqrds the 18" limit on the top parking tile?

Based on instinct, I would say yes. Even though the robot is expanding downwards, its overall vertical height will increase. If that vertical height is greater than 18’’, regardless of whether you are expanding upwards or downwards, it is illegal. Though there is an exception in the expansion zone, that does not contain the parking tiles.

I would ask the Q and A. Its a good question.

Do you have a link and time stamp for that competition? I can’t seem to find it.

No need for a Q&A addition… yes, vertical height is measured from the lowest to highest point on your robot. A robot that is center parked still needs to maintain the less than 18" height restriction.

If you read through SG2, the robot would have to be able to meet the 18" height if it was measured on a flat surface. So if you robot could meet that requirement with say your ramp all the way down and your back wheels on the ground, you could technically be in a legal size. There is nothing that says that it has to be measured with all of the wheels on the ground. I would be very interested to see how a strategy like this plays out.

Here is a Q&A Regarding 18" height and center platform

But, doesn’t the manual or something say something along the lines of “no vertical deminsion may exceed 18” when outside of the expansion zone”? Common sense would tell me this is not legal. I’ll have to look up the exact rules later to confirm. It would be very cool if we find a loophole. (That actively isn’t arched but he GDC)

I’m not sure that that question is relevant to this topic, as it refers to a cubic robot tipping, and we’re talking about a cubic robot expanding downwards. (“Cubic” is used very loosely, only to describe the volume of the robot as per my understanding of the question and serves no purpose other than to simplify a robot’s shape.)

I am not sure what you mean by this - the platforms I believe are part of the expansion zone - so height limited by 18"… If there is an exception where is it described in the game manual?

If the ramp is motor driven and when used on a flat surface (tiles), if the overall height of everything stayed below 18", would this not be legal? Only way I could see this being illegal is if the height is defined relative to the starting orientation of the robot. But there are ways you can easily get around that.(I’ll let you guys figure that out on your own).

Would the work around still fit under 18" if I were the referee and moved the robot to a flat surface to measure it? Since the game manual specifically mentions relative to a flat plane, you might get a referee wanting to move the robot for measurements.

As a reff I would move it to check. You would have to have it meet the height requirement of 18". Also would need to meet the 36" horizontal cylinder expansion.

I actually just asked this exact question in the Q&A and am still waiting on an answer. In the event we hosted on Sat, several robots were DQ’d based on the ref’s interpretation that this was against the rules, and I just want to be sure for future events so I decided to have it clarified. This is the last 30 sec of the finals- the blue alliance was DQ’d based on this rule


Not actually a cylinder. You are allowed to expand horizontally to sizes that would not fit within a 36" diameter cylinder.

Expanding downward would not be against the rules… expanding to greater than an 18" height outside of the expansion zone would be against the rules. Teams could be DQ’d if the violations were repeated and/or egregious or match affecting.

The question is considering overall height and where the measurement starts

Yes, I feel it needs clarification because the word used in the game manual is “height” which in all definitions I have seen refers from the ground up. It does not say “total vertical displacement” which would make it more clear as to what the GDC meant by the rule. For instance, the root structure of a tree do not add to its height, but would be a part of the total vertical displacement.

In the case I showed in the video, platform parking was match affecting, but the hanging of the claw did not benefit the alliance that was DQ’d. It should be noted that the ref team was very consistent about calling this issue this way all day, so there was no argument, but I do think the rule needs clarification for the future.

GDC specifically states:

So there are no “roots” - you take the robot and place it on the floor and measure the height from the floor up.

The blue alliance robot that was center parked measured 17.5" on flat ground. The claw hung down about 0.75" off the platform. They were disqualified.

So the height of the robot is 17.5+.75 = 18.25"

I can see how they would be DQ’d - they could not stay in their size limit to achieve the center park in that case. They could have designed a stop on the claw to prevent it from handing down.