Quote:
Originally Posted by IKE
1718 had a great pincher system as well.
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Thanks. We went through a lot of the same iterations as other teams. Our original design had a single pvc roller on top with nothing on the bottom - the intent was to spin the ball in place in front of the robot. If we backed up, the idea was that the backspin on the ball would keep it rolling toward us. This proved to be very finicky depending on the surface and ball conditions and we would often roll right up on the ball. Adding a backstop didn't work as we would just kick the ball away from us more than anything. We then added a second pvc roller and messed with all different heights; from low to up on the middle of the ball, all with the same results. We then spent some time trying a vacuum system, but after blowing out a couple of f-p motors we gave up on that idea. It became clear that we needed something on the bottom to help grab the ball. This was now after bag day if I recall correctly - we were also still working on the hanger arm, but that's a different story. We'd seen the design of 148/217 online previously and after going to watch events at Kettering for week 1 we noticed teams such as 27 and 67 with the pincher design. We were able to get things designed a ready to put on the robot before the start of our week 2 event at Cass Tech. Two 1/2-inch steel bars, the bottom stationary and the top powered with a window motor. It was driven with a vacuum belt that would slip when it grabbed the ball so we didn't stall the motor. The bars were wrapped with tennis racket tape which seemed to give us just the right amount of stickyness. We wouldn't get a death grip on the ball - if we turned or maneuvered too fast we would lose it, but we were able to grab it enough to turn, aim and shoot. I think the only carrying penalties we took were when we accidentally would drive the ball up the bump and hold it in the air. Of course, the couple times that happened, our driver was sure to shoot it just to make sure the refs noticed it.
From that point on the only changes we made to it was to make a more rigid bracket for the bottom bar and to adjust it's position to get the best grip on the ball without carrying it. Luckily, our rocker on the wheels was only 1/8" so that didn't cause any problems with carrying the ball.