Monitoring of liquid droplets in laser-enhanced GMAW

A laser back-lighting based metal transfer monitoring system for robotic gas metal arc welding

“…The fuzzy region is computed by a linear membership function. The segmentation accuracy is verified by the previously justified method [12][13][14]. The advantage of the double-threshold method over other threshold selection methods [15][16][17][18][19][20][21][22] is its better accuracy in segmenting fuzzy images.…”

“…The advantage of the double-threshold method over other threshold selection methods [15][16][17][18][19][20][21][22] is its better accuracy in segmenting fuzzy images. The advantage of the double-threshold method over the previous angle-edge method [12][13][14] is its better efficiency and all sidedness. The double-threshold method could be used to compute both the droplet and the undetached liquid metal while the angle-edge method could only be used to model the droplet.…”

“…Eqs. (11)(12)(13)(14)(15) are used to detect the edges of the droplet along the direction of the droplet's center to the boundary. The maximum peak is selected and the corresponding position is chosen as an edge.…”

“…The variability of arc plasma in the arc welding causes the variability of the pixel intensity and fuzziness at the edges. To deal with the fuzziness effectively, [12] and [14] have proposed a second order model to fit the detected edges and compute the position and size of the droplet more accurately than threshold segmentation methods [15][16][17][18][19][20][21][22]. In this paper, we will introduce a linear membership function to deal with the fuzzy edge of the droplet and then propose a double-threshold segmentation method in Section 5.…”

“…The image looks noisy and the contrast is low. The effectiveness of the Gaussian weighted kernel moving filter in suppressing the noise has been verified in the past research [11,12]. The Gaussian kernel is formulated below:…”