Abstract: The current state of droplet transfer control methods in pulsed-MIG welding is introduced. The principle of the newest method--droplet transfer spectral control method and its advantage, development, and prospects are described. The spectral signal has many advantages in reflecting droplet transfer in pulsed-MIG welding. Its quality and sensitivity are far better than other signals used before. The droplet transfer spectral control method for the one-peak-zero-base (OPZB) in pulsed-MIG welding is realized. It will be spread to the droplet transfer control of two-peak-zero-base and three-peak-zero-base in pulsed-MIG welding. Even it can be spread to the droplet transfer control in continue current welding. Therefore, the new method has wide technology applicability and a prosperous future.

Key words: Automatic control, Droplet transfer, Pulsed-MIG welding, Spectral information