It seems so simple. You just get that fabric covered box lined up with the spinning wheels and pull it right in. But the box actually has one short dimension, so some times the cross section you are trying to grab is smaller. Also, the fabric covering gets saggy with use, so the one open side of the box is a loose tent.
These wheels looked great but were made out of material that was too squishy. We have to be able to lift this box "in the grip" up to a target six feet in the air.
Finally we did get to where we had all the variables dialed in. The wheels pulled the box in. They spit it back out on cue. You could pick the lift mechanism up, actually it is easier to pick up the whole robot, and shake it. It held. Great, yes?
Well it looks good. We got it mounted on a drive frame and with a mock up of the elevator "mast" that will be in about that position. But, in real world testing a real world problem appeared. When you make a tight turn, or spin around...the spring tension on the intake arms is not sufficient to keep the box from flying out. And since you cannot drive sedately in tournament play this is a serious, no, a fatal design flaw.
Oh, we tried to make it work. Belts, pulleys, different sized wheels, different wheel material. But the basic problem remained.....too much weight out front on flexible arms. You could of course have a pneumatic cylinder pull the arms together once the box was in the grip.
But at that point the wheeled intake becomes rather irrelevant.....just use pneumatics to grab the box.
And so, two weeks into the six week build.....The Claw returns.
Some actual engineering going on now with things being drafted on paper and/or on computer, gear ratios for winches being calculated, metal being milled for elevator parts, software continues to program away.
Its frustrating, all the more so because we will likely lose another day to weather tomorrow. But it moves forward.....
1 comment:
I actually kind of liked reading about the problems 'cause I know you all will work hard on a good solution. ("The joy's in the struggle", C's dad used to say.) So glad you have that great space in which to do all the work. Thanks for all the descriptions and colorful pictures. Hopefully the kids are dreaming of solutions as they lay in their beds on YET ANOTHER SNOW DAY!
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