KAMI KITTASSISTIVE TECHNOLOGY

Chapter 7

Human/ Assistive Technology Interface

T H E H U M A N / T E C H N O L O G Y I N T E R FA C E

Is a major part of the assistive technology component

of the human activity assistive technology model

There are 3 elements of human/technology that

contribute to the operation of a device.

1. The control interface

2. The selection set

3. The selection method

CONTROL INTERFACE

Is the hardware by which the human in the

assistive technology system operates or controls a

device. Also known as an impute device. (e.g.

keyboard, joystick)

Selection Set: The items available from which

choices are made. These sets are represented by

written words, letters, and sentences. The size,

modality, and the type are based on the users need.

SELECTION METHODS

There are 2 basic methods

1.Direct Selection: The consumer indicates his

choice by using voice, finger, hand, eye, or other

body movement

2.Indirect Selection : Uses the method of scanning

which uses switches.

Scanning : requires good visual tracking skills, a high

degree of attention, and the ability to sequence. It requires

very little motor control to make a selection.

Directed Scanning: Allows user to activate the control

interface to select the direction of the scan, vertical or

horizontal.

Coded Access is a sequence of movements a individual

uses to impute code for each item. (e.g. Morse code)

THE PROCESSOR

This is a set of device functions which is referred

to as the Command Domain. Such as a joystick on a

powered wheelchair. Pushing it up is transferred as

forward movement of the wheelchair, down is

transferred as reverse, left moves chair to the left,

and pushing it right makes the chair move to the

right.

KEYB OARD AND MOUSE EMULATING INTERFACES

Transport Access describes 2 fundamental concepts

1.100% of the functions of the computer must be adapted if the

user who has a disability is to have full access.

2.All application software that runs the unmodified computer must

also run on the adapted computer.

There must be a bridge between the control interface and the

computer to use many of the alternatives to keyboard or mouse,

such as an expanded keyboard or a single switch, to access the

computer.

GENERAL INPUT DEVICE -EMULATING INTERFACES

Or GIDEI: defines the characteristics of a special processor that

translates or decodes the signals from the control interface so they

match the command domain requirements of the computer.

A GIDEI set up consists of 3 parts

1.Input Method

2.Overlay

3.Options

See page 219 of text Box 7-3 for more details as well as Box 7-1 on

same page for the major features of commonly used GIDEI

EMULATORS

Mouse Emulation :Substitutes a set of keys, a scanning array, or

Morse code characters for mouse functions.

Emulators use built in synthetic speech feedback to allow the

user to receive auditory and visual prompting and feedback. This

is useful for young children who may not be able to read, for

visually impaired individuals, and for added input for persons with

learning disabilities

Coded Access: A sequence of movements a individual uses to

impute code for each item. (e.g. Morse code)

GRAPHICAL USER INTERFACE

GUI is characterized by 3 distinguishing features

1.Mouse pointer which is moved across the screen.

2.A graphical menu bar, which appears on the

screen.

3.One or more windows , which provides a menu of

choices

CHARACTERISTICS OF CONTROL INTERFACES

Spatial Characteristics

1.Overall physical size, shape, and weight

2.The number of available targets contained within

the control interface

3.The size of each target

4.The spacing between targets.

Activation Characteristics: the method of

activation, deactivation effort, displacement,

flexibility, and durability of a control interface.

Sensory Characteristic: Auditory, somatosensory,

and visual feedback produced during the activation

of a control interface.

ENHANCEMENTS

Rate Enhancement: Augmentative and alternative

communication and computer access approaches that result in

the number of characters generated being greater the number of

selections the individual makes.

Direct Selection Rate Enhancement: deals with encoding

techniques and prediction techniques.

Scanning Rate Enhancement: is based on placement of the most

frequently used characters near the beginning so that they are

scanned first

Control Enhancers: Aids and strategies that enhance or extent the

physical control a person has available to use a controlled interface.

Control interfaces for Direct Selection includes:

• Various types of keyboards

• Pointing interfaces

• Speech recognition

• Eye gaze

• Gesture recognition

• Cortical signals

CONTROL ENHANCERS

Aids and strategies to enhance or extend the physical

control a person has available to use a control interface

Interface positioning, arm supports, mouth sticks head

pointers, and hand pointers.

Control interfaces for Direct Selection include: Various

types of key boards, pointing interfaces, speech

recognition, eye gaze, gesture recognition, and cortical

signals

DIFFERENT TABLES TO VIEW

See figure 7-12 page 238 for different types of keyboards.

See Table 7-9 page 248 for Alternative Electronic pointing

interfaces

See Table 7-8 page 242 for Speech recognition Interfaces

See Table 7-15 page 269 for types of Text-to-Speech Systems

used in assistive Technologies.

See figure 7-9 on page 233 for Selecting a control interface

for an individual.

EYE CONTROL SYSTEMS

There are 2 basic types of systems

1.The first type uses IR video camera mounted below the computer

screen . (e.g. TOBII. If you ever want to see how one runs, contact

me. My little brother uses one at school every day. )

2.The second one used a head mounted viewer that tracks movement

of one eye such as the Vision Key.

Both types provide the user with computer access for written or

verbal communication, internet access, environmental control, and

telephone operation

ALTERNATIVE ELECTRONIC POINTING

Keypad mouse: mouse movement is replaced by

keys that move the mouse cursor

Trackball: looks like inverted mouse; a ball is

mounted on a stationary base. On the base there are

buttons that provide different functions

Continuous input joysticks used for powered

mobility and for computer use.

Head-controlled mouse: the user wears a sensor on

the head, which is detected by a unit on the

computer.

Light pointers and light sensors emit a light beam

that can be used to point to objects.

MOUNTS FOR CONTROL INTERFACE

Keyboards can be placed on stands or easels, some

can be mounted to wheelchairs.

The most common mounting locations are

attachment to a table, desk, wheelchair, or a persons

body.

There are flexible and fixed mounting systems for

individuals who require changes in their position

because of fluctuating needs or skills.

SPEECH OUTPUTS

There are 2 types of speech used in Assistive

Technologies

1.Digital recording: Human speech is stored in

electronic memory circuits for later retrieval.

2.Speech Synthesis: which is the generation of

human sounding speech by use of electronic circuits

and computer software.

QUIZ

http://

www.onlineexambuilder.com/my-dashboard/my-quizz

es/item3240