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Originally Posted by mr.roboto2826
Would you be able to go in depth a little more as to your prototyping process and iteration? I noticed in the photo you had a rail on the bottom of your shooter, but your final design had none.
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The rail in our prototype was to help feed the ball in consistently. It was added quickly after hand-feeding proved to be not reliable enough.
We started by controlling every variable possible. Once we had something that performed well enough, we started looking at the CAD and what the final solution was going to look like. We then measured the prototype and tried to make the model match. Whenever we found a place where we wanted the model to diverge from the prototype, we tweaked the prototype to match the proposed design and re-ran our tests. Our final design has a plate holding the ball until it is grabbed by the wheels, which serves the same purpose. We pulled the bar back until it was just about as long as the final design wanted, and verified that it still worked.
Quote:
Originally Posted by mr.roboto2826
Also could you explain the pneumatic setup on your feeder into the shooter?
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That piston linkage alone took an entire weekend of work. Open up the model and take a look. The left-right spacing is killer, especially since you want a ~3 pound grabbing force.
This year was different in that you didn't need to shoot multiple balls. We chose to use that by designing a shooter to hold one ball very securely and load it very consistently. That pointed us towards designing something which grabbed the ball in a "cage" with pistons and linkages, and some sort of piston loading mechanism. After a couple conceptual iterations in discussions, someone proposed having 2 links where the links were driven relative to each other to grab and release the ball, and the pair of links rotated together to feed the ball into the flywheels. We very carefully worked through all the geometry in solidworks sketches, figured out all the components, and then worked on finalizing the design. We tried at least 4 different piston models before we found a piston that would work.
I'm not sure I explained the pistons the best. Ask for clarification where I wasn't clear enough.