現代的各種機械加工中，焊接是一個廣泛被使用的方法。焊接仍有許多部份仍然是依靠師傅的手藝來完成；尤其是鋼管的焊接部份，遮蔽金屬電弧焊接法是最主要的方法之一。 任何材料與焊接位置均可以採用此方法來焊接。 焊接的性能可以藉由適當的變頻控制而改進，還有其他的控制方法為這個目的而提出；然而，電流回饋控制在實際上的焊接過程的實現很複雜，因為它需要最佳的輸出電流參考波形，和複雜的電流控制增益調整。之前所搜尋的文獻，都把焦點放在氣體金屬電弧焊(GMAW)和亞焊(GTAW)方面的研究，雖然遮蔽金屬電弧焊接(SMAW)在焊接工業上有非常多的應用，但是這方面的研究卻很少。 在焊接過程中，困難的就是由無到有電弧的過程，以及維持穩定的電弧。本論文利用可變結構控制中的滑順模態控制，應用其穩健性：對系統外部干擾，或是系統參數隨環境變動所造成的不定量與無法或獲知的部份系統模式來克服焊接起伏的困難，達成可以順利的起伏生成穩定電弧來焊接的目的。 Abstract Welding is a generally method in the machine manufacture today. There are still a lot of welding works done by a master worker, specially welding steel tube. Alternating current shield metal arc welding (SWAW) is the one of the most important welding method. Any kind of metal materials could be welding, and any way could be used. The welding performance can be improved by appropriate frequency conversion. There are several different control methods to improve this purpose. However, current feedback control in the real system is very complex. Searching for scientific or technical literature, there are focus on inert gas metal arc welding (GMAW) and inert gas tungsten arc welding (GTAW). Although Alternating current shield metal arc welding (SMAW) is widely used in industry, today. Research about the alternating current shield metal arc welding is less. The most difficult part of SMAW is to produce the electric arc from shield metal and to keep the arc current stable. We use the Sliding Mode Control of Variable Structure Control theory in the automatic alternating current shield metal arc welding control system. Employing the advantages of the uncertain of parameter, disturbance, and robust of the sliding mode control theory to overcome the difficult of the electric arc producing and preserve the current stable.
