THIS PROCEDURE WILL HELP YOU MAKE A HEAD POINTING DEVICE, OR HEAD MOUSE, FOR YOUR HOME COMPUTER.

 

 
 

DESCRIPTION

A HEAD MOUSE IS AN ALTERNATIVE TO TRADITIONAL POINTING DEVICES LIKE HAND MICE.  A HEAD MOUSE MOVES THE CURSOR BASED ON THE POSITION OF THE USERS HEAD.  APART FROM USE AMONG DISABLED PERSONS OR RESEARCH, HEAD MICE HAVE NOT BECOME POPULAR DUE TO THE RELATIVE COST AND STEEP LEARNING CURVE INHERENT IN THE SYSTEM.  IN THIS PROJECT YOU WILL BE ABLE TO CONSTRUCT A FUNCTIONAL HEAD MOUSE FROM AN OLD WEBCAM AND A FEW SPARE PARTS.

IN SHORT, THE WEBCAM IS FILTERED TO BE SENSTIVE ONLY TO INFRARED, AND THE SOFTWARE TRACKS THE POSITION OF AN IR LED ATOP THE MONITOR.  THE REQUIRED SOFTWARE IS AVAILABLE FOR FREE DOWNLOAD.
 

MATERIALS        

-WEBCAM.  NEWER WEBCAMS PROVIDE BETTER FRAMERATES.  WEBCAM USED MUST BE IR SENSTIVE; MOST ARE BUT MOST 'X-CAMS' ARE NOT
-PHOTO NEGATIVES (THE DARK, UNEXPOSED END PIECES OF THE NEGATIVE IS ALL THAT'S REQUIRED)
-SOFTWARE AVAILABLE BELOW

EQUIPMENT        

-WINDOWS PC

PROCEDURE

 

WHY?

1.  DISCARD ALL THE USELESS PLASTIC FROM YOUR WEBCAM.  THIS ISN'T REQUIRED, BUT I LIKE IT.

THE AVERAGE WEBCAM IS A LOT SMALLER THAN THE CASE IT'S IN.  DISCARDING IT SAVES A LOT OF WEIGHT AND SPACE.
2.  CUT OFF TWO PIECES OF THE UNEXPOSED EDGE OF A DEVELOPED FILM NEGATIVE.  CUT THESE TO FIT OVER THE LENSE OF THE WEBCAM.  THE TWO PIECES WILL BE STACKED ON TOP OF EACH OTHER. THESE NEGATIVES ARE VERY 'DARK' IN THE VISIBLE SPECTRUM BUT NEARLY TRANSPARENT TO IR.  USING TWO IS REQUIRED TO DIM THE VISIBLE LIGHT, LIKE FROM A NEARBY WINDOW, ENOUGH SO THAT IT DOESN'T CONFUSE THE SOFTWARE.
3.  POSITION THE NEGATIVES OVER THE LENS.  NOTE, SOME WEBCAMS DO NOT HAVE THE LENS ASSEMBLY ATTACHED TO THE CCD SENSOR.  IF YOU REMOVE SUCH A CAM FROM IT'S CASING, YOU'LL HAVE TO GLUE THE LENS, ALONG WITH SOME SPACERS, TO THE CCD.  TRIAL AND ERROR GIVES THE RIGHT SPACING. WEBCAMS ARE IR SENSITIVE, BUT WE USUALLY DON'T NOTICE BECAUSE THE IR SOURCES ARE SWAMPED BY VISIBLE LIGHT.  PUTTING THIS FILTER ON WILL ALLOW IR SOURCES TO APPEAR WHITE IN THE WEBCAM VIEW.
4.  MOUNT THE FILTERED WEBCAM TO SOME MANNER OF HEAD ATTACHMENT SCHEME.  I USED AN EAR PIECE.  THIS WORKS FINE, BUT A HEADBAND IS MORE STABLE.  A BIKE HELMET WORKS TOO, BUT LOOKS REALLY STUPID. UHH, YOU NEED SOME WAY TO KEEP IT IN PLACE ON YOUR HEAD, DUH.
5.  FINALLY, YOU'LL NEED AN IR SOURCE FOR IT TO DETECT.  AN IR LED IS PERFECT, AND YOU CAN POWER IT WITH 5v FROM THE USB PORT.  CONNECT THE LED IN SERIES WITH A 1K OHM RESISTOR ACROSS THE RED AND BLACK WIRES IN THE USB CORD. FORGIVE THIS AWFUL DRAWING; I WAS TOO LAZY TO MAKE A SCHEMATIC.
6.  SIMPLY PLACE THE FINISHED EMITTER ON TOP OF YOUR MONITOR, FACING YOU. THE SOFTWARE WILL TRACK THIS POINT IN ORDER TO CALCULATE THE RELATIVE POSITION OF YOUR HEAD WITH RESPECT TO THE MONITOR.

SOFTWARE

THIS SOFTWARE WORKS BY TRACKING THE LOCATION OF THE IR LED.  THE TRACKING IS SIMPLE; IT SIMPLY POSITIONS THE CURSOR ON THE SCREEN IN THE SAME RELATIVE LOCATION AS THE LED'S POSITION IN THE WEBCAM VIEW. 

THE SOFTWARE HAS SEVERAL OPTIONS ON THE MAIN SCREEN.  THE LARGE DISPLAY AT THE LEFT IS THE WEBCAM OUTPUT; YOU'LL BE ABLE TO SEE A WHITE SPOT THAT IS THE IR LED.  THE OTHER OPTIONS ARE:

"+90" - THIS CHECKBOX IS USED IF YOU'VE MOUNTED YOUR CAMERA 90 DEGREES FROM THE DIRECTION IS WAS SUPPOSED TO GO (I.E. VERTICALLY INSTEAD OF HORIZONTALLY)

"MAGNIFICATION" - THREE SETTINGS, NORMAL, 2X, 3X.  THIS MAGNIFIES YOUR HEAD MOVEMENTS SO THAT LESS MOTION IS REQUIRED TO MOVE THE MOUSE.  IT DOES MAKE IT MORE DIFFICULT TO DO PRECISE MOVEMENTS, HOWEVER.

"AVERAGING" - THE PROGRAM HAS TWO MODES, GROSS, AND FINE.  WHEN YOU MAKE A LARGE MOVEMENT, IT SWITCHES TO GROSS MODE, AND MOVES THE CURSOR TO THE LOCATION THAT YOUR HEAD IS AT.  FOR SMALL MOVEMENTS, THE PROGRAM USES FINE MODE, AND MOVES THE CURSOR BASED ON THE AVERAGE OF THE LAST FEW POINTS RECORDED.  THE AVERAGE SLIDER DETERMINES HOW MANY POINTS ARE USED IN THE AVERAGE.  LARGER NUMBERS OF POINTS WILL INCREASE PRECISION BUT ALSO INCREASE DRIFT AND THE TIME IT TAKES TO CENTER ON SOMETHING.

"DEADZONE" - A DEADZONE, IN PIXELS.  IF THE CURSOR WOULD MOVE LESS THAN THIS MANY PIXELS, THE MOTION IS IGNORED.  THIS HELPS PRECISION, HOWEVER MAKING IT TOO LARGE CAN MAKE THE CURSOR JUMPY.

"CAM SETUP" - THIS OPENS THE WINDOWS VIDEO CONTROL PANEL, ALLOWING YOU TO SET THE ACTIVE CAMERA, AND ITS RESOLUTION.

"160 X 120" - YOU MUST ENTER THE RESOLUTION OF THE CAMERA YOU'RE USING IN THESE BOXES.

DOWNLOAD SOFTWARE

DOWNLOAD SOURCE CODE
 

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