3.2. The “character selection” method
The “characters selection” method uses eye tracking
glasses in order to selectcharacters from a virtual
keyboard, composing free sentences in this way.
Using the “eye tracking” glasses, the patient may
move the focus over a selected key and keep it still for
a given time. This pause shows that the key has been
selected and that character is displayed on the
message area.
One difficulty of this method is caused by the
oscillations of focus position due to the reflections on
the eyeglasses. Because of these oscillations there
may be more than one key selected during a small
time period. In order to filter these false selections, the
application counts the key selections on that time
interval and selects the key which has the biggest
number of selections. In the same time, the keys
selected by these oscillations are magnified in order to
make the selection easier for the patient.
This method allows the composition of more
complex messages, but, in order to obtain good
results, the method requires patient skills for working
with the eye tracking sensor. In time, when the patient
has had enough practice combined with autocomplete
facility, the method can become an easy and fast way
to interact with the computer.