Control Interfaces for Assistive Technology

Hsin-yu Chiang, ScD, OT

Learning ObjectivesLearning Objectives

• Describe the elements of Human/Technology interface

• Describe the characteristics of Control Interfaces

• Learn how to select Control Interfaces for the users

• Identify technologies for direct selection

• Identify technologies for indirect selection

• Other considerations

Elements of Human /Technology interfaceElements of Human /Technology interface

●● Control Interface: input deviceControl Interface: input device

● ● Selection SetSelection Set

●● Selection MethodsSelection Methods

discrete inputs (computer keyboard), continuous inputs (mouse)

Visual (computer keyboard), tactile (braille), auditory(spoken choices)

Direct selection, indirection selection

● ● The processor:connecting the interface to the The processor:connecting the interface to the activity outputactivity output

Generate feedback & activity output

Characteristics of Control InterfacesCharacteristics of Control Interfaces

●● Spatial characteristic: placement and size of CISpatial characteristic: placement and size of CI

● ● Activation & Deactivation Activation & Deactivation characteristic: how it characteristic: how it is activated? is activated?

Its overall size, weight & shape; no. of target within CI; size of target; spacing between target….

• Method of activation:Method of activation:

Movement (eye, head, tongue)

Mechanical CI: keyboard, joystick..

Electromagnetic CI: light detector, IR remote

Electrical CI: EMG

Proximity CI: heat sensitive switch

Respiration (inhalation-expiration): puff & sip

Phonation: sound switch, speech recognition……

• Other activation characteristics:Other activation characteristics:

Effort, displacement deactivation flexibility durability & maintainability

● ● Sensory Sensory characteristic: what feedback is obtained?characteristic: what feedback is obtained?Auditory: click sound Somatosensory: tactile, kinesthetic, propriceptive Visual: color

Select Control Interfaces for the usersSelect Control Interfaces for the users

Outcomes of Needs IdentificationOutcomes of Needs Identification

Outcomes of Physical-Sensory EvaluationOutcomes of Physical-Sensory Evaluation

Control EnhancersControl Enhancers

DirectDirect selectionselection IndirectIndirect selection

ModificationsModifications

Control Interfaces for Direct SelectionControl Interfaces for Direct Selection

● ● Most rapid, preferred over the use of indirect selectionMost rapid, preferred over the use of indirect selection

● ● Some critical questions to ask for keyboard usingSome critical questions to ask for keyboard using

• Can c’t reach all of the key?

• How about the accuracy? At least 75% be correct

• How about the speed?

● ● Some alternative keyboards Some alternative keyboards

Expanded keyboard, contracted keyboard, touch screen, tongue-touch keypad………..

IntelliKeys IntelliKeys (expended keyboard)(expended keyboard)

Ergonomic Keyboard Ergonomic Keyboard (vertical-split (vertical-split

keyboard)keyboard)

WinMini Keyboard WinMini Keyboard (contracted keyboard) (contracted keyboard)

AlphaTalker AlphaTalker (special purpose keyboard)(special purpose keyboard)

• These keys are not assigned any specific functions when manufactured,but can be programmed just about anything the user like.

SofType for TouchScreensSofType for TouchScreens

Tongue-touch keypadTongue-touch keypad

● ● Electronic pointing interfaces Electronic pointing interfaces

• Mouse

• Trackball• Joystick

Features:• Wireless Operation (senor attached to the forehead) • No Cumbersome Head Mounted Apparatus • Precise Pointing • Operates in Conjunction With or Replaces Standard Desktop Mouse

Three-Dimensional Tracking Systems

Head-Controlled Computer AccessHead-Controlled Computer Access

Head-Controlled Computer AccessHead-Controlled Computer Access

Speech Recognition SystemSpeech Recognition System

• Speaker dependent systemSpeaker dependent system

• Speaker independent systemSpeaker independent system

• No training required• Vocabulary set is small, used in ECU & powered mobility

• Recognition depends on the system’s learning the user’s speech pattern

Control Interfaces for Indirect SelectionControl Interfaces for Indirect Selection

• Using a single switch or an array of switches

• The c’t needs to :

• activate the switch and activate at right time

• Selection techniques for scanning

• automatic scanning

• step scanning

• inverse scanning

• wait for the desired selection to be presented

• hold the switch

• release the switch

• Linear

• Selection Formats for scanning

• Rotary

rotary scanning

• Coded access

• Morse code

SwitchXS

http://www.assistiveware.com/switchaccess.php

• Types of single switches

Paddle switch Wobble switch

Leaf switch Lever switch

Sip-and-puff switchSip-and-puff switch

Other considerationsOther considerations

• Integrated control: Use the same interface for several applications

• Mounting system

• Flexible

• Fixed

Flexible mounting system