Browse Prior Art Database

Enhancing Design Robustness using Guardbanding

IP.com Disclosure Number: IPCOM000109916D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 1 page(s) / 45K

Publishing Venue

IBM

Related People

Sumrell, CC: AUTHOR

Abstract

Disclosed is a method of evaluating a product's actual operational performance using Guardbanding. By evaluating a product's functional performance beyond its normal operational limits a failure distribution can be acquired and analyzed to determine the probability of these failures occurring in the customer's office. The effectiveness of functional design changes can be easily quantified.

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Enhancing Design Robustness using Guardbanding

      Disclosed is a method of evaluating a product's actual
operational performance using Guardbanding.  By evaluating a
product's functional performance beyond its normal operational limits
a failure distribution can be acquired and analyzed to determine the
probability of these failures occurring in the customer's office.
The effectiveness of functional design changes can be easily
quantified.

      Each of the "X"s and "Y"s in the figure represents a single
system failure point.  As more systems are tested the data are
accumulated into a failure distribution.  The Guardband value can
easily be calculated by dividing the difference between the customer
specification limit and the mean of the failure distribution by the
standard deviation of the failure distribution or
           I =  (spec lmt - u)  / s.

      This provides a numerical value for the robustness of the
products.  A product's functional performance can be improved in two
ways.  The distribution mean can be moved further from the
specification limits or the variability of the failure distribution
decreased.

      System 1 is a more robust design than System 2 and System 1 is
less likely to be affected by power supply voltage variations or
temperature changes due to its relative position from the customer
specification.

      This method allows designers the ability to quantify functional
design changes and provide more ro...