Build Your Own Autonomous NERF Blaster: Programming Mayhem with Processing and Arduino

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With love in your toolbox, anything is possible.

For my family, Beth, Jack, and Will

About the Author

Bryce Bigger is an interactive designer-developer. He is the founder and principal of The Bigger Design, an interactive company with roots in web design and development but extending to all things digital, including video, 3D, games, and, more recently, physical computing. Bryce has crafted interactive magic for many national brands, including the United States Navy, Oracle, Ping Golf, Lockheed Martin, Chef Boyardee, and the National Institutes of Health.

He created the Sentinel Project, an open-source autonomous foam dart gun system shown at AdobeMAX 2010 to spotlight innovative use of Adobe AIR technology. Recently, Bryce has produced other sizzling foam dart weaponry for clients, including e-mail marketing leader MailChimp.

Bryce holds a B.S. in Media Arts and Design from James Madison University in Harrisonburg, Virginia. He lives in Columbia, South Carolina, with his beloved wife and two sons.

Contents

Preface

Acknowledgments

1 Tinkering

Tinkering Is Not a Waste of Time

Tinkering with Game Boy Advance

Tinkering with MAME Arcade

Tinkering with 3D

Tinkering with Arduino

Tinkering Can Get You a Job

2 Building a NERF Niche

The Sentinel Project

The Design

The Blaster

The Base

The Code

3 Processing Crash Course

What’s Processing?

Getting Processing

Installing Processing on Mac OS X

Installing Processing on Windows

Hello, Circle!

More Circles!

Save the Ellipses!

Don’t Skimp on Structure

Let’s Draw

4 Arduino Crash Course

What’s a Microcontroller?

So Use a Desktop or Laptop, Right?

What Connects to Microcontrollers?

Types of Arduino Boards

Anatomy of an Arduino

Dream, Create, Deploy

Getting Started

It’s Go Time!

What You’ll Need

Installing the Software

Blinky Blink

Wiring an Arcade Button

What You’ll Need

Making Things Move

Awesometer

What You’ll Need

But Wait. There’s More!

Awesome. We’re Done

5 Motion Detection

What You’ll Need

Motion-Sensing Methodology

PIR Sensors

Image-Based Detection in Processing

Computer Vision

Facial Detection with OpenCV

6 Tinkering Pays Off

Project Blueprint: The MailChimp Feces Flinger

The Concept

Project Requirements

Design and Build

Software and Video Streaming

Delivery

The Takeaways

The Feces Flinger—What Went Right

The Feces Flinger—What Warranted Another Look

The Feces Flinger—Lessons Learned

7 Foam Dart Blaster Hackery

Components

Optional Upgrades

Analog Tools

Blaster Selection

The Big Chart

Weight Removal

Option 1: Lithium-Ion Battery Modification

Option 2: Make the Battery Tray External

Option 3: Power-Adapter Modification

Fire Control

8 Blaster Brains and Eyes

Autonomous Turret, Assemble!

Pan as in Rotation System

It’s Webcam Time

Down to the Wiring

Mouse Movement = Servo Movement

Blaster Coding for Processing

Blaster Coding for Arduino

9 Autonomous Avenger Armed

All Systems Enabled

HUDs, GUIs, and FUIs

Tips and Tricks

10 Leveling Up

Cutting the Cords

Manual Control

Death Blossom

Even More Awesome

A Parts List

B The Sentinel Project Build

Instructions for the Prototype Build

Building the Base

C Applied Warfare Tactics

Flanking

Diversion

Choke Point

D Tales from the Toolbox

Save Time, Save Money

Board Up Your Toolbox

Upgrade to a Combo?

Powering Your Project

Blaster Augmentation

Alternate Input

Fancy Up

Index

Preface

Tinkering is an art. While not a fine art, its importance in our society has never been greater. With all the technology available today, it would be easy to let other people figure everything out for us and to never question their information, judgments, or decisions. But that’s not smart for you or for the future of innovation.

Is This Book for You?

This book is a kick in the pants for anyone interested in (even remotely) information technology (IT), coding, design, or physical computing. These aren’t career paths in their infancy; these jobs are here today. This book can help you explore these critical fields using a fun, readily accessible toy that’s popular in many office settings and toy boxes: NERF foam dart blasters. So whether you’re in the fifth grade or a 55-year-old hobbyist, dig in and get ready to explore something new.

Worried?

Even if you don’t know UI from IT, you soon will. This book is written for beginners who want to learn a bit about coding and physical computing. The projects are easy to understand (and easy on the wallet). The code is all open source. The parts are easy to acquire. Many great companies began in a garage. Maybe yours is a launching pad, too.

Go Ahead, Turn the Page

If you’re ready, we can get started right now with a little history, although not the boring kind with dudes in white wigs. This project’s pedigree is arcade video games, handheld hacks, and odd mods. Let the fun begin!

Bryce Bigger

Acknowledgments

This blaster book would not be in your hands without the help of this motley crew:

• My friends and family, who supported me through this endeavor. I’m so glad I can finally say that the book’s complete and I won’t feel awful anymore when you ask if it’s done.

• Julie Turner, who helped me wordsmith a story around a bunch of code and spell said words correctly. My series comma will never be the same.

• Greg Hardin, fellow tinkerer and electrician extraordinaire. My projects wouldn’t have been a success without your guidance, although you don’t seem to remember that I keep my blasters loaded and you always end up shooting me by accident.

• All of my officemates in the WECO building. Thanks for putting up with all the noise and constant foam dart pelting.

• Roger Stewart, my editor, and the rest of the folks behind the scenes at McGraw-Hill. Thank you for thinking my story was this interesting. It is, isn’t it?

• The folks at Adobe—Ben Forta, Kristine Jensen, and, formerly, Ted Patrick—who gave me national attention and my 15 seconds of fame, which I seem to have successfully parlayed into 30 seconds, thanks to Roger.

• The guys at Cables and Connections, who always help when I’m in search of just the right adapter, converter, wire, whatchamacallit of the day.

• Ben Chestnut and Zack Smith at MailChimp, who commissioned the Feces Flinger—my favorite project ever.

• Doug Sumwalt, who got me my first NERF blaster—the Vulcan, the actual foam dart menace used all through the Sentinel Project. It’s retired from service, but it sits on a pedestal in my office and gave me more than you could’ve ever imagined.

• And finally a big, sloppy thank-you kiss to the open source community for creating such wonderful tools— Casey Reas, Ben Fry, Andrés Colubri, Xavier Hinault, and Massimo Banzi.

1

Tinkering

I know why you’re here. You want to make a fully automated NERF® blaster. We’ll get to that soon, but there’s something important we need to address first. Before we can even think about rolling up our sleeves and creating this sweet NERF cannon, you’re going to have to leave something behind.

If you’re like me, and I suspect you are, your parents and maybe even a teacher or two told you on more than one occasion to quit wasting time messing with things—digging inside them, taking them apart, repairing them, or flat-out destroying them. A little something affectionately called tinkering.

The process of tinkering is nowhere near a waste of time. Not even close. In fact, tinkering gave the world some of its greatest inventions—light bulbs, telephones, and that little thing we call the World Wide Web. Sure, some people may think that you’re wasting