Droplet Tracking in Double-Electrode GMAW

Abstract

Controlled metal transfer in gas metal arc welding (GMAW) and its modifications including the double-electrode GMAW implies controllable heat and mass inputs and better assured weld quality. To understand, analyze, and control the metal transfer process, the droplet should be monitored in real time. Due to the fast development and transfer of the droplet, the monitoring speed is a key. A tracking method that takes advantage of results from previous images to speed the processing is advantageous. In this paper, Kalman Filter tracking and Least Square Match tracking algorithms are developed to track a droplet in the innovative double-electrode GMAW after its original position is identified. Experimental results showed that the Kalman Filtering algorithm is not suitable for this application due to the limited life span of each droplet. Instead, the Least Square Match algorithm is effective in tracking a droplet if a universal droplet template can be found and defined. However, there are no universal templates suitable for all the droplets. Hence, a real time template updating and LSM tracking method is proposed to track the droplet effectively. Experimental results verified its tracking accuracy.