Abstract: The validity of welding molten pool image is judged by quantificational information fusion of welding pool image and temperature collected with multi-sensors from the front surface. The temperature field based on semi-ellipsoidal heat source is modified by considering the influence of droplets heat content, which comes into a novel three dimensional temperature field analytical model. The molten temperature of countless positions can be gained by the aid of welding pool image information. The analytical model of real time modified three dimensional transient temperature field is obtained by solving the novel temperature field model super-coupled equation through dampedleast square algorithm and identifying four variational coefficients from semi- elliptical heat source and droplet heat content. The molten width on the rear surface is controlled by PID controller with the aid of the transient temperature model which is proved in the welding process with satisfied result.

Key words: Analytical model, Droplet heat content, Multi-informational fusion, Three dimensional temperature field