We all use to play Action and Racing Simulator games like the GTR Evolution, Live For Speed, Need For Speed Shift, Microsoft Flight sim etc etc and many more...
Need For Speed Shift changed the Racing style a bit Further by pouring huge amount of Physx in the game..
We use to play action games and Racing games more realistic by feeling our self inside the games using some Force Feedback Joystick and Racing Wheels..
Lets make it a bit Further, What if we make an device that can manipulate our Head movement to X-axis Y-axis and z-axis that can be used as Left Right Up and Down..
Now its all been done in just an simple way, all you need is an Webcam with 30fps video recording and an Normal Cap, 1 to 4 LEDS depending upon the setup and some 430 and some 860 ohms resistor and an 9v battery and an small PCB board on/off switch..
Windows xp, vista, Seven are only supported for this setup..

Note: For games like Test Drive Unlimited and NFS Shift Single LED setup is Enough, for games like ARMA II and MS Flight Sim use 3led cap setup..

3Led Cap setup is the best and the easy way to go. Just Follow as i do..

Hardware Setup:

Take the LED that use need, Mostly RED color is equal IR led, and BLUE color is easily visible.. Cut of the top of the Led so that light may travel straight.
Look at the Picture below..

Now connect all the 3Led using an 430ohms resistor for each LED and connect them to an 9volt battery and a switch..
The Finished wiring Setup should look like this..

Note: For single Led setup use an 830ohms resistor on an 9volt battery..

Make an 3Led Cap setup that points the 3 led to make an Triangle while looking from the Front and not even while looking from the side..
Take a look at the PICTURE bellow..

Note: For single Led setup mount the LED in Front of the Cap...

Webcam Setup:
Take your Webcam and cover the Lens with an Photo Negative, so that other light wont enter easily..
If you have no use of the Webcam, dismantle it and remove the IR filter lens ( it will be an small glass with multi color on it )..
Install the Needed driver for it and in the Webcam setup set the EXPOSURE to ZERO and Reduce BRIGHTNESS GAMMA etc etc everything to zero and Turn of the LED if the Webcam has..

Software Setup:

Install the FREE TRACK and then launch the software and select the Source as your Webcam and Go to Model and select 3point cap..
Insert the Reading as they ask to Measure the LED...
Now Click Start and see Whether the Skull moves Left Right Up Down as you move your head.. If its not accurate adjust the measure ment..
Now go to Start-All Programs-FreeTrack 2.2 and Select PPjoy and install the software..
Then Go to control Panel and Click Parallel Port Joystick and the Click ADD and in the Parallel Port Select Virtual Joystick and click ADD, it will install the Virtual Joystick.
when it finishes, again open Parallel Port Joystick and select the PPloy Virtual Joystick 1 and click Mapping and Tick the BOX Modify Mapping For this controller and Click Next, Now Select the Axis you want 2 to 8 and click next Next and Finish the setup...
Mostly 3axis is enough for an Racing and action simulator game..

Note: For Single cap setup only 2axis can be used..

Now go to Free Track and Select the Profile Option and Create an New Profile an name as you like and Adjust the Sensitive of the Axis in-between 0.1 to 0.5, this sensitive give you real type of feeling while turning or else an slight movement of the Head will make an 40degree turn fast...
For rest of the axis Roll Pitch etc keep NONE in the Drop box...

Now go to Output and select all the Option as shown in the Picture below..

Now go to Game Controller option from the Control Panel and Select the Joystick and Click Properties and in the Setting Tab Calibrate the Joystick and make sure you have very Fine Pin Point movement and click Next and do this for all the Axis that you want and Finish the Calibration..
Note: Make sure Free Track running and for Windows 7 user you can find game controller in Device and Printer option..

Now Go to Free Track and keep none for Yaxis and launch the game that you like to use this setup and for look left and Right map the keys by moving your Head Left and Right. Now do the same way for up and Down by Keeping none for Xaxis... After you finish Mapping the Keys, save and exit the game and keep both X-axis and Y-axis enabled and launch the game..
Thats it Guys you will get and free viewing expression in the Game..

Some Troubleshooting:
In Free Track and in the Control Option, map a Key in the Keyboard for center. So each when you map an direction Press the center key so that you will measured as looking straight and map the Next key...
If the FPS is 30 below, go to camera setting and select the USB BandWidth to 8..
If the Camera captures may light than your LED means, move the Threshold to the right a bit and if it does not capture your LED means move it to your left..
The way to use this setup is under an Low Light room..
When you Launch the Free Track and turn on the Led on the cap, the Free Track should recognize your led as three Point as shown in the Picture bellow..

Please feel free to ask any questions..

Tested by me and it work well in Grid and TestDrive unlimited...