CODI: Cornucopia of Disability Information

Accommodating Users with a Mobility Impairment

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.