Patent ID: 7174283
Filing Date: 2007-02-06
Classification: G05B

Abstract:
1. A method for determining a root cause for a drift in at least one of a machine and a process, the function of which is determined by a model describing a relationship between at least one of setup and input variables and at least one output property, comprising: a. Assigning desired output properties for a product of at least one of said machine and said process, and allowed ranges for said properties; b. Assigning original values to said variables for obtaining by at least one of said machine and said process said assigned output properties within said assigned ranges; c. Measuring the various output properties of at least one of the machine and the process; d. When measuring an output property of at least one of the machine and the process that drifts from its assigned value, substituting the measured output properties in their corresponding model equations, and calculating for each variable in each equation its presumed value, assuming it is the sole cause of the drift; and e. Analyzing all presumed calculated variable values and the measured values of the output properties of at least one of the machine and the process to determine the variable that is most probably responsible for the drift.