Patent ID: 7151976

Claim:
A method for detecting a fault condition of a manufacturing process, comprising: a) acquiring data associated with a plurality of manufacturing related variables for a plurality of outputs of a manufacturing process; b) developing a model based on the data for detecting faulty outputs of the manufacturing process; c) automatically identifying which of the manufacturing related variables have a substantial effect on the model for detecting faulty outputs of the manufacturing process using a mathematical algorithm; and d) updating the model by using the manufacturing related variables identified in step c) to improve the ability of the model to detect faulty outputs of the manufacturing process, wherein using a mathematical algorithm comprises, i) identifying a linear equation of a selected variable to the origin of the loadings associated with the mode; ii) identifying linear equations of the manufacturing related variables that are perpendicular to the linear equation of step i); iii) solving the simultaneous equations between every manufacturing related variable linear equation and the linear equation of step i) to obtain a projection point of each manufacturing related variable on the linear equation of step i); iv) determining the distance between each projection point to the origin; v) calculating a correlation coefficient based on a ratio of distance between the origin and each projected point relative to distance of the selected variable to the origin; and vi) identifying the substantial manufacturing related variables by selecting the manufacturing related variables that have a correlation coefficient greater than a predefined number.