G18 Clarification during Climb

We are currently at a scrimmage round, and we tried our climbing mech. We have the winch on the side and the whole robot tilts when it lifts up (you can see the footage below). Another team kindly reminded us that it may violate G18 that states that anything cannot extend further than 12inches outside of the frame perimeter which is relative to the drive base. Looking at our video, I don’t think this is a problem if we climb first when the bar is low. What do you guys think?

Climbing in Action

From the video it looks like you would just barely be OK, have yall done the math to save the world tho?


It’s hard to see from the video exactly how far your hook and rope sticks out the side of your robot. You’re going to want to be able to show that it’s less than 12” at all times during the climb, otherwise you run the risk of drawing large penalties.

If you move the top point on the robot where the rope is routed to be directly above the robot’s CoG, you should climb much straighter. You can do that with pulleys or even an eye bolt to guide the rope.

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Not yet. The thing is that the angle of tilting is gonna be different every time we climb. So it’s hard to simulate.

We were concerned with this so we added an axle to connecting our active stabilizer to our winch mech (our winch is mounted on the climber), this axle allows the robot to stay parallel to the ground with the climber at whatever angle the bar is at. If possible I would add more cables connecting the winch to the climber to stabilize better. In all, this doesn’t look to be a huge issue as it appears your winch is almost perfectly over the center of gravity of your robot so in all climbs (barring excessive turbulence) your robot should be fine and within G18.

Climbing at the end of the bar as you do in the video probably doesn’t violate G18. It looks like you stay within 12" of frame perimeter. However, if you try that same climb in the center position, you’ll almost certainly violate G18, since you’ll hit the same hang angle once you’re off the ground but have much more line still to be reeled in by the winch.


Is it possible to show us a picture? Thx

Best to be able to prove during inspection its impossible to go past 12"

I would concur with this. Keep in mind that having two or more robots climb, everyone will likely want to climb at the same time, so they are all reaching and hooking onto a level bar - that would spell trouble for you.


What are you guys seeing that I am missing? Are we talking about the bar that lifted the hook to the hang bar? Just because it is pointed sideways at the end of the climb does not mean that is extending past the frame perimeter. Remember that frame perimeter is the X and Y axis of your robot, the Z axis does not count toward frame perimeter. This is measured as the robot is normally on the ground.

The level bar is at 63 inches and if only hang you cant pull the bar down to 54 as in the video that’s an extra 10 inches … it looked very close with the low height of the hanger. That 10 " likely would make a difference if the robot turns sideways

I think the concern here is around scenario C in the blue box for G18 (included below). Once they’re latched to the bar and start pulling up, the robot rotates 90 degrees so that the hook that was originally coming out of the top of the robot is now extending out the side.

If (as in the video here) they’re the only ones climbing, it looks like it’s close but that they’re within 12". If someone else was counterbalancing the switch as they climbed, it’s very possible that when they rotate they’re now reaching over 12" from their bumpers to the hook on the bar.

Now I see, it is the hook that is concern not the bar. Thanks

The biggest concern in the video is at about 0:07, when the hook is significantly to the right of your robot (assuming the front of your robot is to the left in the video). The preferred way to climb is with two hooks about as far away from each other as you can manage (e.g. your robot width). If you’re only going to use one hook, try to locate the hook approximately above your robot’s center of gravity.

yeah the best way is to locate the winch based on the CoG, but we have our ball mechanism in the middle, and the winch has to be on the side. We will try to use stuff like eye bolts to center them, but the torque is gonna be high.

When I’m in the shop next I can grab a pic.

Basically that. You don’t have to simulate every position, just be worried about the extremes. If there’s ever a point where it goes past 12", make a change so that it can’t go past 12".

Another problem with the video I posted is that there are no stoppers on either sides to stop the bar to tilt too much. I would imagine that in the actual game, it is even easier for ref to count penalty.

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It’s not just a penalty. There’s a red card involved.

From the Blue Box of G18 (pay attention to point b):

Egregious examples of G18 violations include:
a. extending more than 12 inches (~30 cm) beyond the FRAME PERIMETER to score a
b .extending more than 12 inches (~30 cm) beyond the FRAME PERIMETER to score a
c. expanding to block opponent access to a FIELD element, e.g. GENERATOR
d. expanding into the BOTTOM PORT to disrupt the scoring mechanism

This is the part that worries me. In many matches, there will be several robots in the rendezvous simultaneously. A momentary G18 by one robot might be hard to see if the sight line is blocked by (an)other robot(s) and/or if several robots are climbing.