Patent DE-102011085677-A1 (DE)
Title: Monitoring a laser machining operation to be performed on a workpiece, comprises learning a process environment and classifying a current process result, where learning step comprises monitoring a laser machining process by a camera
Inventor: DUDECK SVEN GERHARD
IPC: B23K26/03
Filed: 2011-11-03
Abstract: The method comprises learning a process environment and classifying a current process result, where the step of learning the process environment comprises: monitoring a laser machining process by a camera and then providing a number of images (B) in time-sequential order for evaluation; determining a first number (p) of first characteristic values for each of the images from a respective picture information, where the first number of the first characteristic values is combined with a partial number of images into a first characteristic space (Mp). The method comprises learning a process environment and classifying a current process result, where the step of learning the process environment comprises: monitoring a laser machining process by a camera and then providing a number of images (B) in time-sequential order for evaluation; determining a first number (p) of first characteristic values for each of the images from a respective picture information, where the first number of the first characteristic values is combined with a partial number of images into a first characteristic space (Mp) and the partial number of images represents portions of the laser welding process; transferring the first characteristic space into a second characteristic space, in which a statistical calculation is performed for the respective first characteristic values of the partial number of images in the first characteristic space whose results of the calculation is memorized for the respective first characteristic values into the second characteristic space; assigning a classification value (pk) to the second characteristic space based on an actual judgment of the result of the laser machining process for a portion of the laser welding process; and reducing the first number of the first characteristic values to the second characteristic values in comparison with a small number of selected characteristic values, which are processed together with the classification values. The laser machining process comprises a continuous or pulsed laser welding method. The first number of first characteristic values is determined for the total picture information contained in the image and/or for selective region of the images. A grey value-focus of the image is determined, and analysis values of a horizontal and/or vertical section are determined by the grey value-focus. The first number of first characteristic values of the first characteristic space is partially normalized to given intervals. The partial number of images is selected in such a way that a binary classification decision is assigned as whole. The first characteristic values are removed from a second feature space and/or a first feature space whose assigned second characteristic values are constant up to one of the correlating first characteristic values, which correlate to each other by a given measurement. The selected characteristic values are subjected to different evaluation. Selected features, which lie below a given distance threshold are removed from the second characteristic space. A distribution of classification values is determined on the basis of the selected characteristic values and the assigned classification values, where the evaluation of the distribution of the classification values is performed by quartile positions. The first characteristic values varying with a respective iteration are selected as selected characteristic values. The number of selected characteristic values is smaller than ten. An independent claim is included for a device for monitoring a laser machining operation to be performed on a workpiece.