Control Interfaces for Assistive Technology Hsin-yu Chiang, ScD, OT

Learning 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 interface ● Control Interface: input device ● Selection Set ● Selection 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 activity output activity output Generate feedback & activity output

Characteristics of Control Interfaces ● Spatial characteristic: placement and size of CI ● Activation & Deactivation 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 characteristic: what feedback is obtained? Auditory: click sound Somatosensory: tactile, kinesthetic, propriceptive Visual: color

Select Control Interfaces for the users Select Control Interfaces for the users Outcomes of Needs Identification Outcomes of Physical-Sensory Evaluation Control Enhancers Direct selection Indirect Indirect selection Modifications

Control Interfaces for Direct Selection ● Most rapid, preferred over the use of indirect selection ● Some 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 Expanded keyboard, contracted keyboard, touch screen, tongue-touch keypad………..

IntelliKeys (expended keyboard)

Ergonomic Keyboard (vertical-split keyboard)

WinMini Keyboard (contracted keyboard)

AlphaTalker (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 TouchScreens

Tongue-touch keypad

● 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 Access

Speech Recognition System Speaker dependent system Speaker dependent system Speaker independent system Speaker 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 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

Types of single switches Paddle switch Wobble switch Leaf switchLever switch

Sip-and-puff switch

Other considerations Integrated control: Use the same interface for several applications Mounting system Flexible Fixed Flexible mounting system