No. Read the above. You have nowhere to support the robot to. You can’t force it up because it’s already pushed the touch pad to it’s hard stop. The rope will be under hundreds of pounds of tension at that point. You cannot push the robot higher and therefore cannot relieve the tension.
This is a good point. I had assumed the same also as an alternative without carefully thinking about it.
I do recall your 2010 robot and didnt realize you had those issues also.
Ours is accessible so looks like we will have to bring that large flat screwdriver head.
Or we can also do the other suggestion earlier with the current draw. Lots of time left to figure this out since our climber already made and it works.
Read what I posted again, you’re literally champing the field and that rope will be under significant tension. Good luck.
Just FYI, I agree with your point that teams need to have a solution to the problem.
However, in this circumstance, the force applied on the rope after hitting the stop at the top isn’t “the full power of the winch + the weight of the robot pulling on the rope…”
Rather, it’s the maximum of the two. (Which is likely to be the “at stall” torque from the winch.)
You could have it so the ratchet is easy to take off. Then you could unwind the rope.
Wait… if you’re using a ratchet wrench, could you not just reverse the direction the wrench is ratcheting?
If you use a ratchet wrench you could clamp the non-ratchet end with a bicycle quick-release lever that can slide in a slot to drop below the wrench when the lever is opened.
Please, go try this with 150 in-lb (or more) on the ratchet.
No…that’s the entire point of the discussion above. If you have a ratcheting wrench, attempt to tighten an already tight bolt. While applying a tightening force, try to flip the ratchet switch. It won’t work. The pawl is under tension as well and you can’t overcome it without significant force…far more than your fingers could apply.
Ah, thank you for explaining.
I’ve been mulling over whether or not it’s legal cut the rope to release the robot. It’s legal for your robot to damage team provided ropes (G15) as long as it doesn’t leave debris on the field, and once the rope has been removed from the Davit it’s no longer considered part of the field (R08 blue box).
As far as I can determine, it would not be legal because up to the point where the rope is cut and the robot is released, it’s technically a person damaging part of the field (even though that part of the field is legally allowed to be damaged by a robot. Just not anything else). But it was an interesting read through the rules.
Apex Robotics is not planning to release our robot in this fashion. But it did make me curious if it’s a quick fix for teams who haven’t planned around this
We’re using a flex-head ratcheting wrench, i.e. just an ordinary ratcheting wrench except there’s a pivot between the head and the handle. In order to lower the robot, we simply undo the velcro strap holding the wrench handle in a constrained position (i.e. between two bolts) and pivot it out of the way. The wrench rotates with the winch as it unspools.
Wow. I was at Lowe’s shopping for ratchet wrenches this evening, and thought of essentially the same thing when I looked at the flex-head wrenges. I was thinking of using a non-flex head, non-reversible wrench, wedging it in a piece of aluminum channel (similar to your two bolts), and lifting it out parallel to the shaft. If you do this, be sure to mark the ratchet wrench as to WHICH SIDE FACES OUT, or you’ll have a useless climber for a match or three.
I concur that with the rules as currently written, it would not be legal (Drive team damage vs robot damage). However, given the preamble to the answer to Q299, I suspect that a question on this topic would get a finding of legal even if it meant a rule change.
The nice thing about the flex-head wrench is that we can constrain the head in-place to avoid that exact problem (though we probably ought to mark it anyway).
For those who are interested, this is the wrench in question:
From my experience, that is much easier said than done (with the non-flexible non-reversing). The wrench always wedged itself pretty tightly against the stop and we still needed to lift or rotate the robot slightly to get it out. There needs to be pretty much no load on the wrench to be able to slide it along the shaft to get it off (or far enough along the shaft to not be impeded). Granted, I’ve always done it using two bolts/screws as the stop, never channel.
I’ll second the comment about marking which side of the wrench needs to be facing out, or which way the switch needs to be flipped if you’re using a reversible wrench. Drill it into your pit crew’s and drive team’s heads. You can never double-check too many times.
Have you tried this after crashing into the top and holding full stall?
Depending on where it is in the gear reduction and the spool diameter it’ll either be completely locked and tough to remove or trivial to remove by hand.
The wrench is right on the spool shaft, and the spool diameter is 1.25’’. It’s got a nice long handle, and I seriously doubt it will be a problem though we have not tried “wedging” the robot like that yet (we will be current-limiting the climbing motor to prevent that, at any rate).
Might as well test “catastrophic failure mode” while you get a chance to do so in a more friendly environment.
After reading all this, maybe it would just be better to climb early and let the robot backdrive as time expires… This seems tricky otherwise.