Sliding Mode Observers For Plasma Signal Identification In Remote Laser Welding

In this paper, a model for the emission of a plasma signal during the zinc coated steel metal fusion phenomenon is proposed. Remote laser welding process and system identification of plasma signal based on the sliding mode observer are presented. The dynamic behaviour of the keyhole is captured using experimental data from the photodiode sensor. A multi-input single-output (MISO) model is designed, the equivalent injection signal using a unit vector sliding mode observer is applied to update the dynamic matrix coefficients. The variation in the model parameters due to process disturbances in the laser fusion phenomenon is captured by recursively updating the matrix parameters, using matrix forgetting factor approach. The simulation result shows an accurate estimation of plasma signal emitted during the laser welding process in the presence of process disturbances. (C) 2015, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.