Marshmallow Turret !!!

My great collaborators

Mindy Wu

Ric Lebre

Henry Cheung

Project description

We are building an Arduino-controlled turret that fires marshmallows at people/zombies/aliens/etc. Once completed, this project will have great applications, from defending our school against Caltech intruders to fighting against the First Order.

Mechanical design

Mindy developed a great structure out of an Amazon packaging box.

Mechanical design

Here is how it works. The sequence below can be easily programmed into an Arduino board.

To load

(1) Rotate the servo out of the way

(2) Pull the string with the DC motor until the movable arm is at its lowest position

(3) Rotate the servo back to jam the movable arm

(4) Rewind the DC motor to loosen the string

To fire

(5) Rotate the servo and unblock the movable arm

Electronic design

How to rewind a DC motor

Since it was hard to find a suitable integrated H-bridge chip, we decided to build our own H-bridge. Two relays are used as SPDT switches. The circuit diagram is shown here:

H-bridge

Current direction control

Pin 7 = HIGH, Pin 8 = LOW Pin 7 = LOW, Pin 8 = HIGH Pin 7 = HIGH, Pin 8 = HIGH Pin 7 = LOW, Pin 8 = LOW
A---B B---A No current No current

Arduino layout

Layout

Marshmallow Headquarters on PC

We wrote a GUI by C# that talks to the Arduino board through a serial port. Therefore, besides controlling our weapon by pushbuttons, we can also load and fire on a computer.

GUI

More features to be expected!

(1) Rotating turret controlled by the GUI: aim at your enemy with your mouse!

(2) Voice control: use your vocal cord as a trigger!

(3) Auto-targeting with IR sensor: nowhere to hide!

(4) Auto-loading and multiple shots per trigger: an automatic weapon!