Friday, December 13, 2013

Initial challenges and design changes


In this video, we explain the major design changes we had to make due to the lack of torque on the two control servos.  The servo wasn't strong enough to lift and hold the release angle control arm in the original design.  The spring tension control servo was also too weak to stretch the spring in varying ranges to give different tensions as we had envisioned.  Because buying stronger servos were out of our project budget, we decided to make the following design changes to overcome the problems.

-The long catapult arm had to be shortened in order to downscale the catapult.
-The release angle control arm had to change to a lighter, one-arm design.
-The spring tension control arm had to change to a thinner and smaller design.
-The spring attachement point on the spring tension arm had to be moved closer to the axis of rotation

-The control scheme had to be changed to a firing button and a release angle control, foregoing the spring tension control due to the tension needing to be set to max to get any decent range when fired.
-The tension control arm will be automated for every shot as there is no need to control it any more.  Pushing the firing button will pull the spring tension control arm to maximum angle, release the catapult long arm, lower the spring tension control arm, and return the release latch with enough delays between actions to make a smooth, automated fire and ready state.

So the coding will need to be changed and the wires will be tidied up when all functions are complete.

- TEAM CATAPULT

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