Robotic Catapult

I designed the parts for a robotic catapult!

The catapult is controlled via an Arduino with and L293D motor control shield attached. There are two servos’: one controlling the aim, or rotation of the main platform. And the other acts as a trigger for the catapult arm. There are 2 DC motors, those little 6-12V ones that come in most RC car kits, which are used to control the winch. The winch is attached to the catapult arm via some copper wire. There is a limit switch, which is used to determine when the catapult arm has been pulled back far enough back. The catapult arm is attached to two pillars with two tension springs, which give it the force required to fling stuff!

When the code starts, it runs an aim routine moving 90 degrees to the left and the 180 degrees to the right, before returning to the 90-degree starting point. It then triggers the firing motion which rotates the DC motors backward, one the DC motors push the limit switch they stop, and the trigger servo turns 100 degrees to block the arm from firing. Once the servo is in place the DC motors rotate in the opposite direction for a short period of 400 milliseconds providing some slack on the copper wires. Finally, the trigger servo turns back to its starting position, allowing the arm to fire.

Non 3D printing parts:

1 x Limit switch
2 x Servo - I use one 9g micro servo for the trigger and one MG90
19 x M3 nuts and bolts
8 x M5 nuts and bolts (can be 3D printed)
1 x M8 nut and bolt (can be 3D printed)
2 x Tension springs
1 x Arduino (Uno/Mega/Leonardo - whatever)
1 x L293D Motor Control Shield
err x Some Copper Wire or String

All the code to control the catapult, as well as the original design files, which were modeled in Blender can be found on github here: https://github.com/Tvtig/Catapult

I have marked this as a work in progress as there are still some things I would like to change, such as printing a mount for the Arduino, motor control shield and breadboard - perhaps in one of the stands somewhere.

Support me and my wacky ideas on Patreon here: https://www.patreon.com/tvtig and on my YouTube channel here: https://www.youtube.com/c/tvtig

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