Page 473 - Biomedical Engineering and Design Handbook Volume 2, Applications

TECHNOLOGY AND DISABILITIES 451

accessed through a touch screen. The displayed information is changed based on previous entries.
For example, a general selection set might consist of categories such as work, home, food, clothing,
greetings, or similar classifications. If one of these is chosen, either by touching the display surface
directly or using scanning, then a new selection set is displayed. For example, a variety of food-
related items and activities (eat, drink, ice cream, pasta, etc.) would follow the choice of “foods”
from the general selection set. Thus, the user does not have to remember what is on each level. Cook
and Polgar (2008) describe typical approaches used in AAC system design.

15.5 AIDS FOR MANIPULATION

Many individuals who have limited function of their arms and hands experience difficulty in manip-
ulating objects, controlling appliances (e.g., television, telephone), reading a book, or feeding one-
self or self-care. Assistive technologies that aid manipulation may be simple mechanical aids (e.g.,
reachers, enlarged handle eating utensils), special-purpose electromechanical devices (e.g., page
turners or feeders), or more general-purpose devices [e.g., electronic aids to daily living (EADLs)
and robotics]. In this section we will discuss only EADLs. The others are described in Cook and
Polgar (2008).
Many objects that need to be manipulated are electrically powered devices such as appliances
(e.g., television, room lights, fans, and kitchen appliances such as blenders or food processors),
which use standard house wiring (110 V ac in North America). EADLs are designed to allow
people with limited upper extremity function to control these appliances. A typical EADL for turn-
ing appliances on and off is shown in Fig. 15.1. The user control interface may be a keypad as
shown or a single switch with an indirect selection method. The appliances are plugged into mod-
ules that are controlled by the EADL. The most common type of on/off module is the X-10. ∗ Three
types of wireless transmission are used in EADL design. The most common is infrared (IR) trans-
mission like that used in most TV remote units. A second method, also sometimes used for TV
control, is ultrasound transmission. The third method, often used in garage door openers, is
radiofrequency (RF) transmission. IR and ultrasound require line-of-sight transmission. RF transmis-
sion does not have this requirement. ZigBee is one form of wireless technology that is ideally suited
for low data rate applications such as EADLs since it provides all the advantages of RF transmis-
sion and has low power consumption (meaning longer battery life) and long range of operation
(range enough to control the whole home from anywhere inside it, not just the immediate room)
(Bessell et al., 2006).
The system of Fig. 15.1 may be modified to include remote control over TV or VCR functions
such as volume control, channel selection, play, fast forward, and reverse. In this case the level (for
volume) or number (for channel) is under the control of the human user. Often these functions are
incorporated into EADLs by modifying standard TV or VCR remote controls. This may be done by
merely adding a single switch to the remote control or by more elaborate adaptations that allow
indirect selection. Sometimes universal remote controls that can “learn” the signal for a particular
TV or VCR are used. This allows several appliances to be controlled from the same EADL. Cook
and Polgar (2008) describe several commercial approaches to this type of EADL.
Persons with physical disabilities of the upper extremities often have difficulty in carrying out the
tasks associated with telephone use. These include lifting the handset, dialling, holding the handset
while talking, and replacing the handset in its cradle. There are several options for accomplishing
these tasks. Nonelectronic methods such as mouth sticks or head pointers can be used to press a
button to open a line on a speakerphone, dial, and hang up. EADLs perform these same telephone
tasks electronically. For persons who require single switch access to the system, the control interface
is connected to a control unit that also interfaces with a display and with standard telephone
electronics. A typical approach is for the device to present numbers sequentially on the display, and

∗ X-10 Powerhouse System, Northvale, N.J.