D. Accommodating Users with a Mobility Impairment
The general category of mobility impairment includes individuals with a wide
range of mobility limitations and accommodation needs. This section will
cover a variety of alternative input options. Many individuals with mobility
impairments are able to clearly determine for themselves which alternatives
will be most useful. Others may need the assistance of a rehabilitation
engineering specialist to determine their needs. For some individuals,
positioning of both themselves and their equipment plays a key role in its
usefulness. In consultation with the individual, managers should determine
whether additional assistance is needed in determining the optimal
accommodation solution.
KEYBOARD ENHANCEMENTS AND ALTERNATIVE KEYBOARDS
There are several software packages that can make using a standard PC
keyboard easier for a person with a mobility impairment. If an adequate
accommodation cannot be made to the standard keyboard, there are several
alternative keyboards that may be of benefit.
- Sequential keystroke input - Many of the popular software
programs in use today have commands that require the user to
depress more than one key at a time to execute the command. For
an individual typing with a head stick or a mouth stick only a
single key can be pressed at one time. An individual with
functional use of only one hand, or the use of only a few fingers,
may be able to execute some multiple keystroke commands, but not
all of the required combinations. Software programs are available
that will allow the user to enter the keystrokes in sequence, one
after another, rather than simultaneously and still execute the
command properly. For example CTRL-ALT-DEL keys are all held down
together to perform a soft reboot on a PC. With the accommodation
package running, CTRL is pressed, then ALT is pressed, then DEL is
pressed and a soft reboot still occurs. This capability is often
referred to as "sticky keys."
The same result may also be achieved by using a hardware solution
instead of a software solution. There are several different
hardware options available. A device can be added to many
keyboards that will mechanically hold a key down for the user.
The user would need to hit the keylatch again to release that key.
There are also keyboards with this keylatch capability built in.
Once the control, alt, or shift keys are pressed, they remain
pressed until they are released. Another alternative available is
a keyboard that has a switch setting that lets the user easily
switch between the standard keyboard operating mode and a
keylatched operating mode. Considerations:
- Automatic release of the "latched" key - Does the key stay
"latched" after the command is executed or does it automatically
release? If it stays latched, that is an extra keystroke the user
will need to execute to release the key and continue typing or
entering the next command.
- Single user or multiple user PC - Is the PC used by the only the
individual needing the accommodation, or is it in a shared use
environment?
- How easily can the user move in and out of the "sticky" key mode?
- Hardware configuration and software compatibility considerations
- See the "General Hardware Configuration and Software
Compatibility Considerations" listed at the beginning of this
appendix.
- Key repeat rate control - Both hardware options and software
options exist that allow the individual PC user to adjust the
sensitivity level of either a standard or alternative keyboard or
completely turn off the keystroke repeat function. This can be
very useful for an individual who may be executing stray
keystrokes accidently when attempting to execute a desired
keystroke. This is also a valuable aid to individuals who are not
able to release a key fast enough after it is depressed to prevent
characters from being repeated inadvertently. Considerations:
- What is the range of sensitivity levels the user may chose from?
- Can adjustments be made easily?
- Can the key repeat be turned off completely?
- Hardware configuration and software compatibility considerations
- See the "General Hardware Configuration and Software
Compatibility Considerations" listed at the beginning of this
appendix.
- Keyboard macros - Software and hardware solutions exist to allow
a few keystrokes to be automatically translated into multiple
keystrokes that have been previously chosen. The reduction in the
number of keystrokes that must be entered can be significant.
Keyboard macros are a productivity improvement tool for anyone,
but particularly for a person that has difficulty using a
keyboard. Considerations:
- While within an application, can macros be added or changed or
must the user exit to the operating system level?
- Can multi-line macros be generated? For example, can a macro be
used to generate a signature block?
- How long can the macro abbreviation be? Some packages limit the
macro to being a single key, others allow a multikey abbreviation
such as initials or acronyms. Many users prefer the multikey
abbreviation due to the ease of remembering them.
- How many keystrokes can be generated with a single macro?
- Can the user display a listing of the macro abbreviations and
the associated expanded word or phrase?
- How many macros can be stored and available?
- Hardware configuration and software compatibility considerations
- See the "General Hardware Configuration and Software
Compatibility Considerations" listed at the beginning of this
appendix.
- Miniature keyboards - Some individuals with limited mobility may
find a smaller, more compact keyboard easier to use. Many
individuals with a limited range of motion or functional use of
only one hand may find a miniature keyboard useful. There is one
version of a small keyboard that uses infrared control to
eliminate the direct connection to the PC. It may be used to
control the PC from several feet away. Considerations:
- What is the keyboard layout? Is it the standard QWERTY layout
or a different key configuration?
- How much pressure is needed to activate a keystroke?
- Are the keys accessed by hand or using a special device such as
a pointer or light pen?
- Is there a built in method for sequential keystroke input?
- How does the miniature keyboard attach to the PC? Does it plug
into the standard keyboard port or does it use a serial port or a
different specialized interface?
- Is there any software that must also be loaded for the system to
use this keyboard?
- Are there any other special features? One keyboard allows
different settings to be chosen for key sensitivity.
- Can the user see the keys adequately? For an individual with
low vision in addition to their mobility limitation, a miniature
keyboard may help one problem and intensify another.
- Are all of the function keys, cursor routing keys, and numeric
keypad keys on the keyboard being replaced also available on the
alternative keyboard?
- Hardware configuration and software compatibility considerations
- See the "General Hardware Configuration and Software
Compatibility Considerations" listed at the beginning of this
appendix.
- Expanded keyboards - Individuals who have difficulty controlling
their arm or hand movements, or those unable to accurately select
keystrokes on the more commonly used keyboards, may find an
expanded keyboard useful. Expanded keyboards are larger,
oversized keyboards that give a much larger surface area for each
key. This design improves accuracy for many individuals.
Considerations:
- What is the keyboard layout? Is it the standard QWERTY layout
or a different key configuration? Can key assignments be changed
if the layout is not acceptable?
- Are all of the function keys, cursor routing keys, and numeric
keypad keys on the keyboard being replaced also available on the
expanded keyboard?
- Is the entire area of each of the larger keys active? Can any
part of the larger key be used to select that key or are there
inactive or "dead" spots on the key?
- Is there a built in method for sequential keystroke input?
- How does the expanded keyboard attach to the PC? Does it plug
into the standard keyboard port or does it use a serial port or a
different specialized interface?
- Is there any software that must also be loaded for the system to
use this keyboard?
- Can the user reach all of the keys on the keyboard?
- Is a keyguard available for this keyboard if needed?
- Hardware configuration and software compatibility considerations
- See the "General Hardware Configuration and Software
Compatibility Considerations" listed at the beginning of this
appendix.
- Alternative keyboard layouts - There are both hardware and
software options available to remap the keyboard to a layout more
optimized for a single handed keyer. The software options allow
the user to choose between the standard QWERTY layout, right
handed Dvorak, and left handed Dvorak layouts. Hardware solutions
are available for either the two handed Dvorak, right handed
Dvorak, or left handed Dvorak layouts. Considerations:
- Is the user already familiar with the QWERTY layout? Do they
want to relearn a new keyboard layout?
- Is the PC used by a single person or in a shared use setting?
- Does the software option also offer keycap covers to identify
the new key designations once the Dvorak layout has been loaded?
- If the software option is used, how easy is it to switch between
keyboard layouts?
- Hardware configuration and software compatibility considerations
- See the "General Hardware Configuration and Software
Compatibility Considerations" listed at the beginning of this
appendix.
- Mouse alternatives - A number of application packages in use
today depend on mouse input for fully utilizing the program. Many
users that may be unable to carry out the sweeping movements
needed to control a mouse may be able to benefit from the mouse
alternatives currently available. Some of the alternatives
include:
- Keyboard equivalents - Many programs that depend on the mouse
also offer keyboard keystroke equivalents to accomplish mouse
movements
- Trackballs - A trackball is a stationary object that utilizes a
ball that may be rolled with the fingers, palm of the hand, or
foot to move the screen cursor. The trackball also has buttons to
perform the click and drag functions associated with using a
mouse. When selecting a trackball, attention should be given to
the positioning and size of the buttons. Can the user easily and
comfortably position the ball without inadvertently hitting the
buttons?
- Hardware configuration and software compatibility considerations
- See the "General Hardware Configuration and Software
Compatibility Considerations" listed at the beginning of this
appendix.
NON-KEYBOARD DEPENDENT INPUT MECHANISMS
When a keyboard solution does not provide an optimal accommodation for the
individual, there are several additional alternatives that may be considered.
Keystroke equivalents are sent to the computer through these alternative
devices. All methods for selecting keystrokes can be roughly broken into
three types: direct selection, encoding, and scanning. A brief discussion of
these approaches may be helpful to understanding the technical considerations
associated with available products.
Direct selection refers to any method that allows the individual to choose a
specific character, word, or phrase with a single selection. Most individuals
may not be aware that using a standard keyboard is a direct select method.
Speech recognition is an example of an alternative direct selection input
method. The biggest advantage of direct selection over either encoding or
scanning methods, is that it is often the quickest since each selection made
results in an actual keystroke, word, or phrase being generated. Encoding and
scanning systems are employed when an individual is unable to use direct
selection techniques.
Encoding refers to a method where each keyboard character or phrase is
assigned a unique pattern code. When this code is entered, the associated
character is generated. An example of encoding is Morse code. Each
character has a unique set of dots and dashes associated with it.
Scanning is a technique that presents groups of characters to the user on a
display. As a cursor moves from one group to the next automatically, the
user first selects the group needed, and then the character within that
group. For each keystroke equivalent, two selections are required. A
variety of switch inputs such as sip and puff, muscle switches, and
eye-tracking systems can be used with scanning systems.
Speech Recognition
Speech input is a direct selection alternative that can be successfully used
by many individuals that are unable to access the keyboard at all or have
very limited use of the keyboard. As each word is spoken clearly and
distinctly it is recognized and presented on the computer screen. There are
both low-end and high-end speech recognition packages available. Currently,
both the low-end and the high-end solutions require a distinct pause between
each word spoken for the speech recognition to be accurate. Current
technology does not support accurate recognition at a normal conversational
rate of speech.
The low-end solutions have a limited vocabulary set and each word must be
specifically "trained" by the individual user. Several of the speech
recognition packages have predefined overlays of commands that support rapid
vocabulary training for use with popular word processing, spreadsheet, and
database application packages. Within the limit of the active vocabulary at
one time, the user can add words and their associated keystrokes to the
available vocabulary set. To make the functional vocabulary larger and run
faster, some packages organize the vocabulary sets to correspond to the
commands needed in a particular portion of the application. The speech
recognition system operates faster since it does not compare speech patterns
of words that will never be used in that application module. The vocabulary
training consists of going through a menu of the words and speaking each word
three or four times to build a voice pattern for that word. These systems
can be very effectively used in situations where a small vocabulary is
needed, such as entering inventory codes into a database or speaking the
commands within an application package. The inventory codes could be spoken
as digits and letters. In some cases, the speech input may be much more
error free than keying long alphanumeric strings, regardless of whether the
individual has a disability or not.
The high-end solution has a 30,000 word dictionary and the user can add other
words and terms as needed. A user can successfully start using this system
after specifically training only 10 to 40 words. The system continues to
improve its match to the users' voice and "self-train" as the individual user
speaks into the system and corrects the word selections the system displays.
Commands, typically consisting of a phrase, can be added to the dictionary
and entered verbally. On the high-end system, typing speeds up to 35 words
per minute can be achieved by an experienced user who trained the system to
their voice patterns.
Individuals with significantly altered, but consistent, speech patterns can
successfully train the speech recognition system to their voice. This is
true for both the low-end and the high-end speech recognition systems. Using
the high-end system, the individual may have a significantly lower
recognition rate initially to each word compared to the "standard"
pronunciation dictionary. As the user makes corrections and continues to use
the system, it will continue to self-train itself to their voice pattern just
as it does with users with more easily understood voice patterns. Once
trained, the speech recognition system can recognize the vocal commands of a
user with a speech impairment with greater accuracy than individual
listeners. The key to the successful use of the system is speech
consistency. If an individual's voice changes significantly over the course
of the day as they become fatigued, several speech recognition packages offer
the capability of storing multiple voice patterns. As the error rate for one
voice pattern becomes unacceptable, the user would switch to their second
"fatigued" voice pattern.
Considerations:
- What application programs will the user be using? Does the
speech recognition package have any predefined vocabulary overlays
for the commands needed by the application packages?
- What size vocabulary is needed?
- How easy is it to add words to the vocabulary set?
- Will the package allow several speech recognition templates to
be stored for more than one voice, or more than one user?
- Does the user have consistent speech?
- How quickly does the user's voice tire?
- Microphone considerations:
- How much background noise can be present without adversely
affecting the speech recognition?
- Can the microphone be mounted so the user does not have to wear
it or be tethered to the PC by a cord? Many wheelchair users that
may not be able to independently put on and remove a headset
microphone would like viable alternatives that will allow them
freedom to leave the PC without assistance from another person.
Is there a cordless microphone that can be used?
- Is there a voice command for turning the microphone on and off?
- Hardware configuration and software compatibility considerations
- See the "General Hardware Configuration and Software
Compatibility Considerations" listed at the beginning of this
appendix.
- How much disk storage is needed by the software? How much is
needed by other application packages?
- Are the PC internal speeds and the speed needed by the speech
recognition board compatible? What speed PC is required for the
speech system to work? What is the maximum allowable PC speed at
which the board functions properly? If the speech recognition
board needs a slower clock speed than the PC normally runs at, can
the PC clock speed be slowed down? Most PCs have a utility for
doing this, although it may be difficult to find the specific
command needed in the user's manual.
Other alternative inputs
There are several additional alternative input options for individuals that
have voluntary muscle control over some part of their body. Some of these
will be described below:
- Morse code input, an encoding system, utilizes Morse code with
added features to make it more adaptable for use with a PC.
Considerations:
- Mouse needs - If the application is dependent on the use of a
mouse, are there keystroke equivalents to accomplish mouse
movements? If so, can the Morse code system execute these
keystroke equivalents?
- Switch input - Some users are able to control two keys or
switches with one key being for dots and the other for dashes.
Others need a package that will allow both dots and dashes to be
generated from a single key or switch.
- Can a single key or dual key switch be used with the system?
- Can keys on the PC keyboard be used as the input mechanism?
- Has the Morse code set been expanded to include the extra keys
on the PC keyboard? Does it have all the keys needed?
- Does the package allow for macros to be added?
- What input speeds can be achieved once the user has mastered the
Morse code patterns?
- How does the system handle code errors?
- Is there a training component to the system to help the user
master the Morse code?
- Hardware configuration and software compatibility considerations
- See the "General Hardware Configuration and Software
Compatibility Considerations" listed at the beginning of this
appendix.
- Infrared pointing devices consist of a receiver, a reflector,
and associated software that may be used in place of a keyboard.
The individual points the reflector at a picture of the keyboard
being overlaid on the computer screen by the software used with
the pointing device. Each letter or word can be selected directly
and then appears on the computer screen. Considerations:
- If the application packages being used are dependent on the use
of a mouse, are there keystroke equivalents to accomplish mouse
movements? If so, can infrared pointing systems execute these
keystroke equivalents?
- Can the size of the selection keyboard displayed on the screen
be changed?
- Is the amount of time the individual must stay focused on the
desired key adjustable?
- How is the pointer device attached or connected to the user?
- Hardware configuration and software compatibility considerations
- See the "General Hardware Configuration and Software
Compatibility Considerations" listed at the beginning of this
appendix.
- Sip and puff systems are one of the popular interfaces for
scanning systems. Other types of interfaces that may be used with
scanning systems include muscle switches and joystick controls.
The choice of interface device depends primarily on the user and
their preferred method of control. A sip and puff interface
allows the user to scan with one action, such as sip, and select
with the other action, such as puff. If the user is scanning a
set of characters, they would sip to keep scanning, and then when
they were at the character desired, puff to select the character.
Many of the systems that can utilize a sip and puff interface
allow the user to choose which action they want to be used for
scanning and which for selection. Muscle switches employ the same
principle with the voluntary tightening or loosening of a muscle
being the scan or select controls. Switches can be set up for
detecting eye blink, or eyebrow twitch in addition to other muscle
movements such as hand or finger movements. Joystick controls may
be used by an individual with adequate control of finger movement
or can be controlled by chin movements. Considerations:
- If the application packages are dependent on the use of a mouse,
are there keystroke equivalents to accomplish mouse movements? If
so, can the scanning interface chosen execute these keystroke
equivalents?
- Can the scanning rate be adjusted?
- How is the user attached or connected to the interface device?
Is the interface device attached to the computer? Can the user
move away from the computer and come back to the interface without
intervention from another person?
- How large is the scanner the user must see? How easily can it
be repositioned?
- Can the groupings being presented be changed? How easily?
- Can macros be added to the system? Or can an additional macro
package be used in conjunction with the scanning package?
- Hardware configuration and software compatibility considerations
- See the "General Hardware Configuration and Software
Compatibility Considerations" listed at the beginning of this
appendix.
- Eye scanning packages are also now available that operate
similar to a pointer system but do not require anything to be
attached to or connected to the user. A camera focuses on the
individuals eye and tracks the movements of the eye. As the
person focuses on a screen of choices or a menu seen on a monitor,
the system will display the selection on the PC screen. An
individual that has no voluntary control of muscle movement at
all, but can still focus their eyes, can control a computer.
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