This seminar topic delivers a new method to guide and control the wheelchair for disabled people based on their eyeball movement. In this method use sensor based eyeball tracking system to control powered wheelchair. Eyeball sensor will generate distinct range of values for each position of eyeball (i.e. left, right, straight). This concept can be used for multiple applications, but this paper focuses the application to mobile and communication aid for paralytic people. The system involves two stages; first eyeball tracking and second sending of control signals to the arduino controlled wheelchair.
Inside house paralytic people reaching a desired destination is little bit difficult. So, paralytic people can’t move freely inside their house they depend on others for their motion. Here with the help of eyeball movement detection system, the new idea of providing a cost effective, less hardware complex embedded system that helps the paralytic people to move freely inside their house.
DIFFERENT EYE TRACKING MECHANISMS
There are three eye tracking mechanisms to compute the position of pupil.
Electro-Oculogram (EOG) Method:
The Electro-Oculogram method obtains the gaze direction by sensing the electro-oculographic potential. This is done by measuring the potential using electrodes placed on face where human eye is an electric dipole with a negative pole at the fundus and positive pole at the cornea. One electrode is placed to the side of the left eye and another to the side of the right eye. This pair shall detect horizontal eye movements. One electrode is placed above the left eye and another below the left eye. This pair shall detect vertical eye movements. A fifth electrode is attached by the ear to provide reference voltage. These electrodes send the electrical signals to two EOG circuits of similar design to detect the horizontal and vertical movement of the pupil. This information is sent for computation. The big advantage of this method is the ability to detect eye movements even when they are closed.
Lens Tracking Systems
In this method a non slipping contact lens fits over corneal bulge. The tracking of the pupil is recorded by affixing a magnetic coil or mirror to the lens. The integrated mirror in the contact lens allows measuring reflected light; alternatively, the integrated coil in the contact lens allows detecting the coil’s orientation in magnetic field. The big advantage of this method is high accuracy and nearly unlimited resolution in time. Both methods explained so far are obtrusive and are not suited well for interaction by gaze. The third and preferred method for eye-gaze interaction is using video camera.
Head Mounted Camera System
The most common mechanical setup involves use of desktop computer with integrated eye tracker camera. The desktop computer is loaded with software package for analyzing the eye gaze data. This setup require head fixation and hence restricts the head movements. An alternative method uses a head mounted eye tracking.
In this seminar topic proposals importance is to serve all types of paralytic people to move freely to smaller distances inside their residence. This system uses only eyeball detection using eyeball IR sensor. The sensor consists of two parts infrared transmitter and receiver.
Infrared transmitters and receivers are housed into a single unit and fixed in front of the goggles. Necessary wirings are takes through the goggles to the sensor processing. The person should wear the goggles for the sensor to work. Since the sensor is shielded it can be isolated from the external light, thus external light illumination will not affect the sensor output values.
- The existing eye tracking methods for locomating the powered wheel chair are based on image processing techniques thus it is tedious to work with images. But our system uses only eyeball sensor which tracks the position of the eye by using a simple components light dependent resistor, comparator, IR led.
- Calculating the threshold values of position of the image processing techniques are complex but using the eyeball sensor we can easily calculate the threshold values.
- Using the eyeball sensors instead of the CCD camera will also reduce the cost of the total system dramatically.
- Application to mobile and communication aid for paralytic people.
- Medical Field.
This system consists of eyeball sensor, microcontroller and wheelchair. The above mentioned hardware along with the software proved to be the great tool which makes the life of the paralytic people independent. This system can also be extended to locomotion of the wheelchair in reverse also. We can also implement obstacle sensors in this system which will be very helpful to the paralytic people in dodging the obstacles. The system can be extended to control the equipments around such fans, lights, etc.