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Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/11261

Title: A Novel Asynchronous Access Method for Minimal Interface Users
Authors: Silva, Jorge
Advisor: Mihailidis, Alex
Department: Biomedical Engineering
Keywords: asynchronous access
control
accessibility
disabled
disability
physical impairment
access
binary interface
single-switch
human-machine interface
Issue Date: 1-Aug-2008
Abstract: Current access strategies for minimal interface (e.g., binary switch) users employ time-coded (i.e., synchronous) protocols that map unique sequences of user-generated binary digits (i.e., bits) to each of the available outcomes of a device under control. With such strategies, the user must learn and/or reproduce the timing of the protocol with a certain degree of accuracy. As a result, the number, κ, of device outcomes made accessible to the user is typically bound by the memorization capacity of the latter and by the time required to generate the appropriate bit sequences. Furthermore, synchronous access strategies introduce a minimum time delay that increases with larger κ, precluding access to control applications requiring fast user response. By turning control on its head, this thesis presents an access method that completely eliminates reliance on time-coded protocols. Instead, the proposed asynchronous access method requires users to employ their interfaces only when the behavior of the device under control does not match their intentions. In response to such event, the proposed method may then be used to select, and automatically transmit, a new outcome to the device. Such outcome is informed by historical and contextual assumptions incorporated into a recursive algorithm that provides increasingly accurate estimates of user intention. This novel approach, provides significant advantages over traditional synchronous strategies: i) the user is not required to learn any protocol, ii) there is no limit in the number of outcomes that may be made available to the user iii) there is no delay in the response of the device, iv) the expected amount of information required to achieve a particular task may be minimized, and, most importantly, v) the control of previously inaccessible devices may be enabled with minimal interfaces. This thesis presents the full mathematical development of the novel method for asynchronous control summarized above. Rigorous performance evaluations demonstrating the potential of this method in the control of complex devices, by means of minimal interfaces, are also reported.
URI: http://hdl.handle.net/1807/11261
Appears in Collections:Doctoral
Institute of Biomaterials and Biomedical Engineering - Doctoral theses

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