|
 In
a nutshell
Imagine the
user and her/his Assistive Technology represented schematically;
somewhere there’s a dotted line. There’s the person
and there’s the … stuff; and between them is a dotted
line. This is the boundary. This is where the person touches
or talks
to or otherwise affects the device, and this is where the device
displays
or does something to the user. This is the user interface.
Formally,
and phrased in general enough terms to cover the full range
of real and future AT, the user interface is:
The hardware
and the operational rules through which the user acts on the
device;
and the displays and actuators through
which the device
acts on the user.
This is one
of those definitions which sounds somewhat abstract but snaps
into clarity once one has seen a
few examples.
It’s also
a definition which is inclusive enough to cover all
devices used by all people. It can be applied to jet cockpits and
pianos as readily
as AAC devices and power wheelchairs. (Note
that sometimes the user interface is a built-in feature
of an all-in-one-box
device, for
example the keyboard on a portable communicator, while
in other systems it’s physically separate out at
the end of a cable or a wireless connection, like the remote
control
for an environmental control
system or standard TV.)
Let’s
use these four examples to give this definition some concrete
reality.
- In an aircraft
cockpit, the rudder pedals, control stick, throttle, flap
controls and all the various switches
and
levers on the
instrument panel constitute the input interface.
The visual gauges, navigational
displays, weather radar screens and warning tones
in the headphones – as
well as the sites like the seat surface and controls
where the airplane pushes back on the pilot: these
are all part of the output or feedback interface.
- Sitting
at a piano, the keyboard (with
its particular logic of white and black keys and pitch rising
to the
right) plus
the foot
pedals make up the input or control interface
while the strings and the hammers and the sounds
they
produce are
the output interface.
- Users of
AAC devices may control these products through single switches,
keyboards with
letters,
touch screens
with pictures,
joysticks, microphones and/or breath-pressure-sensing
tubes – the input interface – and monitor the results,
along with their conversational partners, through
an
output interface consisting of synthetic voice
output, text display on a screen, or printed
hard copy
- And the
wheelchair driver: the control interface through which s/he
operates her/his
vehicle
may include a joystick
for her/his
hands, feet, chin or head, along with (or
replaced by) various switches and
buttons and voice-input microphones and lap
tray touch pads – all
or any of this to produce motion of the chair
which has an output effect on her/him through
LED displays of remaining batter power,
and the forces felt through the seat, seatbelt,
seatback, armrests and footplates.
|
