2

SPARK

Robot that

shoots you

in the face

imply put, this is an intricately designed, far-from-

practical, over-the-top robot that shoots you in the

face. It uses a dirt-cheap Logitech webcam, three servo

motors, an Arduino, a Nerf gun, and some code from

projectsentrygun.rudolphlabs.com to track your face

and shoot it.

The robot has X-axis and Y-axis modules, mounted on a simple

wooden frame, that support and move the shooting mechanism – a

toy Nerf gun. Each axis and the trigger of the Nerf gun is controlled

by high-torque Futaba servos. A webcam mounted at the top of the

wooden frame is used to locate your face.

The servos controlling the axes and the trigger are controlled by

an Arduino that is programmed to use processing code running on

my laptop. This processing code is the brain of the computer vision

functionality of the robot. The original code aimed a paintball gun at

the chest of a person but, with a few quick modifications, I managed

to get it to aim at my face reliably.

This processing code spits out coordinates that are sent to the

Arduino, which controls all three servos to correctly position and

shoot the gun. The servos have a heavy current draw and need an

external 5 V power supply. For testing purposes, I added an external

switch with a servo controller to fire the gun.

Now, considering that I have essentially built an automated turret,

I just had to add a green laser as a sight to satisfy the stereotypes

of every futuristic weapon ever, thanks to sci-fi movies. The laser

needs 3 V, sourced from the power supply using an LM317-based

voltage regulator.

I believe in building over buying and reusing as much as possible,

and so I kept the build as inexpensive as I could. The wood is all

recycled pallet wood from a florist and the metal parts are scrap

aluminium from e-waste. I used a modified ATX power supply to

power it all with stable DC 5 V. The electronics were the only part of

the build that I did not manage to find a recycled source for.

S

By Mihir Vardhan Makingwithmihir.com

Left

Mihir’s on a mission to show that

making can be cheap and fun