Browse Prior Art Database

Designs of Instrumented Pens for Signature Verification

IP.com Disclosure Number: IPCOM000088756D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 4 page(s) / 50K

Publishing Venue

IBM

Related People

Lew, JS: AUTHOR

Abstract

This article describes two types of simple accelerometer configurations for an experimental pen, which simultaneously meet five desirable requirements of a measurement system for signature verification.

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Designs of Instrumented Pens for Signature Verification

This article describes two types of simple accelerometer configurations for an experimental pen, which simultaneously meet five desirable requirements of a measurement system for signature verification.

A technical enterprise of current interest is to implant measuring instruments in a special pen, record numerical data during signature production, and verify personal identities through some computational algorithm. Some previous workers have used mechanical devices inside a pen, for example, to observe the variable pressure of the pen point on a recording medium [1]. Other recent investigators have placed accelerometers inside a pen, as well, to capture some aspects of the pen motion during an individual signature [2]. This article proposes accelerometer configurations for a special pen which meet plausible requirements for an efficient system. The ultimate design may either combine such accelerometer configurations with pressure measurements, or else use these configurations without further instrumentation. Available technology provides suitable accelerometers; available skills permit such pen designs.

The following requirements of an accelerometer configuration are plausible goals for a measurement system. (1) The system should distinguish arbitrary motions of the special pen without prior assumptions about "normal" movements.
(2) The system should employ the smallest number of measuring instruments compatible with other criteria for design effectiveness. (3) The system should permit numerical calculation of the pen motion with minimal danger of uncontrolled error magnification. (4) The system should yield a special pen with the most normal "feel" compatible with efficient response to other criteria. (5) The system should facilitate simple calculations for important physical quantities as potential input data for verification algorithms. No present system, to this author's knowledge, meets this complete set of requirements.

A standard accelerometer for such purposes measures a single component of the local acceleration. This article presumes such instrumentation. Then requirement (1) demands at least six accelerometers, whence requirement (2) specifies precisely six accelerometers. To describe the configuration of these six instruments, we fix a rectangular coordinate system in our special pen, placing the coordinate origin at the pen point and aligning the z axis with the pen axis. We describe the installation of the i'th accelerometer by specifying two 3 1 column vectors in this coordinate system:

(Image Omitted)

The (arbitrary) vector r(i) gives the location of the corresponding instrument; the unit vector e(i) indicates the direction of the measured component.

Let r(i) e(i) denote the standard cross product of vector analysis, let

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denote the 66 matrix with the indicated

1

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columns, and let det(B) denote the standard determinant of this matrix...