Mechatronic Project

For this project Me, Zach, and Kevin built a ballista style catapult.

Here is a picture of the setup workspace
https://drive.google.com/file/d/0B8ZGdT5f3eJkRklSTHRwR240ZXc/view?usp=sharing

Here is a video of the catapult in action
https://drive.google.com/file/d/0B8ZGdT5f3eJkUkRJTFhqZm1ndms/view?usp=sharing

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The two types of machines we used here were
A DC motor used to wind up a "chain" that pulled the loaded chamber back.
This machine uses a circular motion to build up potential energy in the rubber bands holding the loaded chamber

A Servo Motor that acted as switch to release the chain holding the chamber to fire the catapult.
This was a conversion of rotational energy into a much larger amount of energy built up in the rubber bands.
By using a small force to release a built up larger force, this machine acted similarly to how transistors work.

Miscalculations and Problems
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This particular project had more problems than any previous project.
First, building a steady structure for the ballista was near impossible given the funds available.
The structure was built out of chopsticks and tape.

Second, the DC motor had no textured surface attached to the spinning pin. As such it was difficult to get a chain to rotate with the motor pin.
This was resolved with thread, needles, a cut rubberband, and super glue.

Third, the rubberbands really didn't hold enough power to launch our projectiles very far.
Rather, the structure wasn't built long enough to pull the chamber back far enough.
However, given the weak rotational power of the DC motor, it was impossible to make the structure any longer.

Given these problems, this catapult is more a proof of concept to show that the design works.
It isn't ready to be mass-produced and marketed as a weapon of damage.