Browse Prior Art Database

Computer Input Device Via Nerve Signal Detection

IP.com Disclosure Number: IPCOM000035849D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 3 page(s) / 79K

Publishing Venue

IBM

Related People

McLean, JG: AUTHOR [+4]

Abstract

This article describes a method by which traditional chord-keyboard typing motions are translated into computer input signals without the presence of a physical keyboard. This invention may also have applications in aiding partial amputees to use a computer or computer-aided devices.

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Computer Input Device Via Nerve Signal Detection

This article describes a method by which traditional chord-keyboard typing motions are translated into computer input signals without the presence of a physical keyboard. This invention may also have applications in aiding partial amputees to use a computer or computer-aided devices.

The input device, shown in Fig. 1, takes the form of an elastic cuff 10 with built-in EMG (electromyographic) sensors 11 at the locations of major muscle- triggering nerves. The cuff is worn between the wrist and elbow of the user, where the forearm 20 is the widest, Fig. 2. The sensors 11 detect the nerve signals which result in muscle movement of the fingers. Electronics 21 are used to filter these signals for noise reduction, so that the signals are accurately converted from analog to digital form for computer input 22.

Five EMG sensors 11, spaced approximately 10 millimeters apart, are on the lower inside portion of the cuff so that they contact skin

(Image Omitted)

at the location of the Superficial Flexor muscle for each of the fingers and the thumb. These electrodes detect nerve signals to these muscles intended to flex (curl) the finger. Various combinations of fingers are flexed to indicate disparate words or characters. The cuff 10 is elastic so that people of various arm sizes may use the same device. The sensors spread apart as the elastic expands, so that placement is automatically adjusted for arm size.

A second-order, low-pass, Butterworth filter 21 is the signal- processing filter of choice for the following reasons. It filters out noise above its cutoff frequency at 40 dB/decade. This filter is designed to be maximally flat from DC to the cutoff point frequency, and it has an optimal damping ratio. Since this Butterworth filter does not introduce a time lag and it gives a feedback proportional to the EMG activity, it is the best choice for EMG signal processing for this disclosure.

After being filtered for noise reduction, the EMG signals are converted into alphanumeric characters by a computer 22, such as an IBM PS/2. The IBM PS/2 could execute the user's instructions, activate...