HOW TO MAKE AN EYE MOTION CONTROLLED MOUSE?

PROJECT IDEA & DESCRIPTION

When the eyes move, biopotentials are generated. These corneo-retinal potentials (from the back of the eye to the front of the eye) biopotentials are generated by the retinal dipole, and variously called the EOG (Electro-oculogram), ERG (Retinogram) or ENG (Nystagmogram). The potentials vary with a number of factors, e.g. light level, blinking, and tends to drift.

• Use electrodes on the forehead, under the eyes on the cheek, and behind the right ear (mastoid) for the grounding point.
  
  
  
  • These three electrodes could be mounted on the eyeglass frame
  
  
  
  


• Design and build a suitable instrumenattion amplifier to detect the EOG
  
  
  
  • Suggested circuit schematic - 3-op-amp differential amplifier +  3-pole Butterworth lowpass filter +  Inverting amplifier
  
  
  
  


• Characteristics of EOG signal and requirements for mouse
  
  
  
  • Frequency Range DC – 10 Hz
  
  
  • Voltage Range 0.05 – 3.5 mV
  
  
  • Gain needed  ~5,000
  
  
  • Approximately linear over 30 degree arc
  
  
  • Accurate to 1 degree
  
  
  
  


• Use a TTL comparator to generate a 1 or 0, or generate a signal proportional to the eye angle.


• Couple to mouse port of PC

CIRCUIT DIAGRAM