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Keyboard Alternative

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Accessing the wide array of functions that smartphones, tablets, and PCs can offer is important in everyday life for healthy individuals and for those with disabilities. Text entry is a traditional input mechanism to communicate those technologies. This article introduces some popular devices as well as specially designed layouts for text entry. The speed of the text entry is a useful way to compare the performance of different assistive technologies against each other. Ease of use, availability, and cost are also important factors in choosing a keyboard alternative. Related technologies include mouse alternatives and augmentative and alternative communication.

Mouthstick being used to input information into a computer
Mouthstick being used to input information into a computer

Contents

Alternative Devices

Speech Recognition

Speech recognition is one of the fastest text entry devices among assistive interfaces. The texts from the user's voice are typed while he/she speaks through a microphone. Dragon is a popular commercially available speech recognition software [1]. Speech recognition has the drawback that outside noise can affect performance. The text entry of an average users has been reported to be as high as 107 words per minute [2].

Mouthstick

Mouthstick is an older technology and can be considered low tech, but is a popular device that provides computer access for people with disabilities. It is relatively cheap and easy to learn, but requires certain degree of head/neck motion. People with disabilies could enter text at 8 words per minute after 30 hours practice [3].

Integra-mouse with sip and puff
Integra-mouse with sip and puff[4]

Sip and Puff

Sip and Puff devices use the breath of the user to control a computer or another assistive technology such as a Sip n Puff wheelchair drive. These devices are commercially available. The Integra-Mouse is a device that has all the functions of a computer mouse controlled by lip movements and uses sip and puff control to control clicking[5].

EMG Control

Electomyography (EMG) involves recording or sensing the electrical energy that occurs during muscle contraction. Commercially available sensors and amplifiers are available that convert EMG into control inputs for computer based systems or motorized wheelchair control. The Tinkertron EMG Switch was developed by an engineer at Georgia Tech[6] and has been licensed to Broadened Horizons[7].

Gaze Tracker

TOBII eye tracking system
TOBII eye tracking system

Eye gaze and eye tracking include devices that use a camera to convert eye movement into an input control for a computer. There are many available commercial versions including expensive high-end systems and freeware systems that use a web-camera[8]. Gaze tracker is a proportional control device and while useful for controlling a mouse cursor or pointer, it is not as efficient for entering text for on-screen keyboard as other devices. Familiar users were reported to type with 6.8 words per minute[9]. Eye tracking system with a special-designed layout, called "Dasher" can be used to type with a rate of 30 wpm with experienced users[10].

Head Tracker

Head tracking systems use an infrared camera to track a small reflective marker mounted on the user's head movement. The device can type about 6 wpm after 72 hours training using a specific on-screen keyboard layout[11].

Smart Nav
Smart Nav[12]

Tongue Control

Tongue control has been investigated as a computer control. The majority of the devices being developed are in the research stage.

  • Inductive tongue-computer interface uses inductive sensors (coils) that change their inductances if a ferromagnetic material is placed nearby. Typing speed for this device was reported to be 5.7 wpm after 20 hours training[13].
  • Tongue Drive System translates the tongue movements as commands and control the computer and wheelchairs by attaching a small magnetic tracer on the tongue. The familiar TDS user can type with the rate about 3 wpm[14].
  • Tongue Touch Keypad was a commercially available device by new Abilities System Inc that has been discontinued. Pressure sensors were activated by tongue pressure. This system was reported to perform at 4 words per minute after 30 hours training[2].
Inductive tongue computer interface(left), Tongue drive(center), Tongue touch keypad(right)
Inductive tongue computer interface(left), Tongue drive(center), Tongue touch keypad(right)

Alternative Interface (layouts)

Edge write
Edge write

Edge Write

Edge write is designed for a unistroke text entry interface by integrating with other input devices (e.g. stylus, trackball, joystick, touch pad, etc.) By using three different devices (PDA stylus, wheelchair joystick, and touchpad) with the Edge Write interface, an expert's speeds were reported to be 23.0, 12.8, and 19.1 words per minute respectively[15].

Dasher

Dasher is an interface consisting of a user controlled pointer and word prediction. The predicted character will appear with a larger target area than unlikely characters. It does not require to switch a mode from writing mode to another control modes[16]

Dasher can be adapted to work with other existing assistive technologies. One example is combining an eye gaze tracker and Dasher. This can lead to increases in speed and efficiency, such that the speed of typing could be more than three times faster than the original design[17].

EZ Keys

Using EZ Keys to write a letter
Using EZ Keys to write a letter

Ez Keys was a popular commercially available word prediction software and speech output program developed by Words Plus. It is intended to be used with a Switch Scanning System and can be operated with a single mouse click, an external button, EMG switch signal, or any other device that is able to provide a switch signal to the computer. Stephen Hawking, diagnosed with ALS, uses EZ Keys in his computer-based communication system to write email, surf the internet, and write lectures in notepad[18]. Words Plus was acquired by Prentke Romich Corporation and shut down. Recently as of July 29, 2013, AAC Works acquired Words Plus and resumed operation under the Words Plus name[19].

References

  1. http://www.nuance.com/dragon/index.htm
  2. 2.0 2.1 Karat, Clare-Marie, et al. "Patterns of entry and correction in large vocabulary continuous speech recognition systems." Proceedings of the SIGCHI conference on human factors in computing systems. ACM, 1999
  3. Lau, Cynthia, and Stephanie O’Leary. "Comparison of computer interface devices for persons with severe physical disabilities." The American Journal of Occupational Therapy 47.11 (1993): 1022-1030
  4. http://switchedonmedia.com.au/blog/screen-readers-and-assistive-technology-5-ways-to-improve-web-accessibility/ Accessed Dec 7, 2013
  5. http://www.click2go.ie/featured-articles/integra-mouse/
  6. http://emgswitch.com/?page_id=10
  7. http://www.broadenedhorizons.com/emg-switch
  8. http://www.tobii.com/ TOBII eye tracking system
  9. San Agustin, Javier, et al. "Evaluation of a low-cost open-source gaze tracker." Proceedings of the 2010 Symposium on Eye-Tracking Research & Applications. ACM, 2010
  10. http://www.inference.phy.cam.ac.uk/dasher/ Dasher for special needs. Retrieved 10/31/13
  11. Hansen, John Paulin, et al. "Gaze typing compared with input by head and hand." Proceedings of the 2004 symposium on Eye tracking research & applications. ACM, 2004
  12. http://www.naturalpoint.com/smartnav/
  13. Caltenco, Héctor A., Björn Breidegard, and Lotte NS Andreasen Struijk. "On the tip of the tongue: learning typing and pointing with an intra-oral computer interface." Disability and Rehabilitation: Assistive Technology 0 (2013): 1-11
  14. Huo, X., et al. "A Dual-Mode Human Computer Interface Combining Speech and Tongue Motion for People with Severe Disabilities." IEEE transactions on neural systems and rehabilitation engineering: a publication of the IEEE Engineering in Medicine and Biology Society (2013)
  15. Wobbrock, Jacob O., et al. "Text entry from power wheelchairs: edgewrite for joysticks and touchpads." ACM SIGACCESS Accessibility and Computing. No. 77-78. ACM, 2004
  16. http://www.inference.phy.cam.ac.uk/dasher/ the Dasher Project
  17. Ward, D. J., & MacKay, D. J. (2002). Fast hands-free writing by gaze direction
  18. http://www.hawking.org.uk/the-computer.html
  19. http://www.words-plus.com/