I have been asked to investigate providing a disabled user with the means to
operate an existing book-page turner.
This device usually uses a suck / blow switch with two levels (hard / soft)
of suck and blow providing 4 commands.
The user has Multiple Sclerosis and is unable to reliably use the suck/blow
system
Other users would also have similar needs.
A complication is that minimal funding is available. This is not necessarily
a limitation but a lower cost solution would be nice.

The user has reasonable head position control and it was suggested that I
could provide a light beam pointing system where the user pointed a head
mounted light beam at 4 optical receptors mounted above the page turner.
This should be a reasonably straight forward solution:
- Use a laser pointer
- Possibly modified to provide beam modulation.although this should not bee
necessary at such short range.
- Optical saturation from ambient light should be easy to avoid in this
application.
- Provision of a timed "beam on" period with turn on enabled by eg looking
upwards at a greater than usual angle would remove the otherwise annoying
red spot on the reading material :-)

HOWEVER

It occurred to me that the availability of low cost video cameras in various
forms (serial port, parallel, USB, separate video ...) should allow a
reasonably low cost solution where the camera monitored a target and
detected head orientation. This could still include a head mounted target or
source but this could be more discrete and if active it could be infrared
and pulsed. While this sounds eminently achievable there would almost
certainly prove to be "more to it" than meets the eye at this stage. Such a
system is notionally more expensive in material cost than a headpointer /
beam system but would be more flexible, more easily adapted to related uses
and less user intrusive.
A rudimentary camera based defined-object location system could have a range
of other uses in disability aid applications.

On reflection (no pun intended) it might be easier to use the camera to
detect where a beam falls on a target than to look at the user and attempt
to determine where the beam is pointing. The "target" could be a wall or
screen above the page turner. The user need not necessarily be able to see
the beam. While this is effectively just replacing optical detectors with a
single wide area detector the above points re flexibility etc still apply.

Has anyone had experience of similar systems and / or can offer useful
suggestions that may help reduce design time.



regards

        Russell McMahon

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