On line control of optimal setup of a laser sheet system for real time monitoring of welding

A methodology is presented able to continuously check the settings of a vision system for automatic geometrical measurement of welding, having a complicated shape. The simple optical measurement system is based on a laser sheet. The set calibration methodology allows the measurement system to reach level of uncertainty adequate for automatic dimensional checking of welding, even though a simple measurement system is used. The effect of varying the lighting conditions has been carefully studied, that is a relevant cause of uncertainty. The method appears very sensitive to little deviations from optimum setting in many operating conditions. The effects of process variability on the method are also studied and quantitatively evaluated; practical solutions for on line use of the proposed methodology are finally discussed.