Face Detection and Tracking With Arduino and OpenCV

UPDATES

Feb 20, 2013: In response to a question by student Hala Abuhasna if you wish to use the .NET Serial class, use the naming convention "\\\\.\\COMn" and replace n with a number > 9 to define your com port for COM ports above 9 such as COM10, COM11, etc.
Mar 23, 2012: Featured on Adafruit's Blog
Mar 23, 2012: Featured on Interactive Design
Dec 13, 2011: Featured on Floss For Science

This guide will also be maintained on my blog http://techbitar.blogspot.com/2012/04/face-detection-and-tracking-with.html

INTRODUCTION

In this project I have assembled a face detection and tracking system. You can see the video of the final project here:

Basically, the webcam sends video frames to OpenCV running on a Windows PC. If OpenCV detects a face it will track it and calculate its center's X,Y coordinates. The coordinates are then passed on to the Arduino via a serial USB connection. The Arduino controls the movement of the webcam with the help of two pan/tilt servos to follow the detected face.

OpenCV (Open Source Computer Vision Library: http://opencv.willowgarage.com/wiki/) is an open-source library that includes several hundreds of real-time computer vision algorithms. The OpenCV 2.x library is a C++ API.

This is an integration project between hardware and software tools. The image processing C++ code samples are provided with the openCV library and all I did was to modify the sample code for this project. I removed some of the unnecessary code and added serial communications to it so it can send X,Y values to Arduino.

CREDIT

This project would not have been possible without the team who developed OpenCV. I also benefited from Ryan Owens' tutorial (http://www.sparkfun.com/tutorials/304) which is based on Processing, OpenFrameworks, and an earlier version of OpenCV. I tried to install Processing and OpenFrameworks with no luck. So Instead, I opted for Microsoft Visual C++ 2010 Express and the latest version of OpenCV which is 2.3.1 without any middleware or wrappers.

TOOLS

Software Required

Arduino IDE 1.0 for Windows
OpenCV 2.3.1 SuperPack For Windows
Microsoft Visual C++ 2010 Express SP1
Serial C++ Library for Win32 (by Thierry Schneider)

Code Required

- OpenCV C++ (attached) techbitarFaceDetection.cpp (based on OpenCV's example facedetect.cpp)
- Arduino's (attached) cam_servo.ino (based on Ryan Owens' example SerialServoControl.pde)

Hardware Required

- PC preferably running Windows 7 SP1. The faster CPU the better.
- Arduino Uno or compatible + power source.
- Standard servos X 2.
- Webcam w/UBS interface.
- Breadboard.
- Jumper wires.
- Hobby wire to tie pan/tilt servos and webcam together.

Step 1: Installation and Integration Issues

1) Download and install the OpenCV-2.3.1-win-superpack.exe if you don't wish to deal with generating the support files yourself. Everything you need from OpenCV to build this project has already been generated in this download.

http://sourceforge.net/projects/opencvlibrary/files/opencv-win/2.3.1/

2) Download and install Microsoft Visual C++ 2010 Express

http://www.microsoft.com/visualstudio/en-us/products/2010-editions/visual-cpp-express

The OpenCV installation documentation explains how to make Visual C++ aware of the OpenCV support files (include, bin, etc). This is not a one-click job. Careful attention must be given to how Visual C++ must be configured to recognize OpenCV files.

The OpenCV team tested version 2.3.1 and Visual C++ 2010 on Windows 7 SP1. If you are using a different configuration, be prepared for a few hiccups.

Step 2: Attach Servos and Camera

I did not want to affix any of the project parts permanently because I like to take my projects apart after I am done. So I used hobby wire, which is nothing more than a stiff wire, to tie the servos and the webcam together.

I wrapped the base of the webcam to the pan servo horn. Then I wrapped a cable around the horn of the tilt servo and the body of the pan servo.

To keep the whole servo/webcam assembly from moving randomly during operation, I used a clamp to tie it down to the soldering helping hands. It kept is steady during servo rotation.

It ain't pretty but it works.

Step 3: Wiring the Parts Together

The wiring is straight forward. I used a breadboard to make the connections.

SERVOS
The yellow/signal wire for the pan (X axis) servo goes to digital pin 9.
The yellow/signal wire for the tilt (y axis) servo goes to digital pin 10.
The red/Vcc wires of both servos go to the Arduino's 5V pin.
The black/GND wires of both servos go to Arduino's GND pin.

WEBCAM
The webcam's USB goes to the PC. The C++ code will identify it via a number representing the USB port its connected to. .

ARDUINO
The Arduino Uno is connected to the PC via USB. Take note of the COM port the USB is connected to. You can find the com port from the Arduino Tools/Serial Ports menu. You will see a check mark next to the active USB port. This is the com port that you will use in your C++ code to communicate with Arduino.

You must change the C++ code to match the PC's com port and baud rate with Arduino's. Also, the C++ code must be told which USB port the webcam is using.