Backup Launcher
During the early stages of the project, we were unsure of the functionality of the pneumatic launcher. We decided to simultaneously design and build the pneumatic launcher, as well as a backup in the event that the pneumatic launcher was inadequate in this application.
Catapult:
We decided to build a catapult. The result can be seen above. Ultimately, we chose to proceed with the pneumatic launcher for our project. It proved accurate and repeatable enough for our project. It could also fire at great distances. While accurate and repeatable, the catapult was unable to match the range of the pneumatic launcher.
Trigger Mechanism:
The trigger mechanism was made of 3D printed parts and a servo motor. At the midpoint of the arm of the catapult, a section of paracord was tied in a loop. The trigger was designed to anchor the loop around the knob while the wiper of the servo was in the set position. Then, the loop is released when the wiper is released, which allows the catapult to fire.
The servo was controlled via software. Two buttons were programed to rotate the wiper. Button two rotated the wiper to the set position. Then the user would manually draw the arm of the catapult and set the loop around the knob, as shown above. Finally, when button one is pressed, the wiper moves to the fire position, releasing the arm.
Demonstration:
