Capability, Flexibility, and Legacy of PI Hinder Market Penetration Prospect of SOSM for Control of GMAW Process

Abstract

A control concept is matured through its increased utility in the market place. Although traditional sliding-mode control (SMC) with its simple control function seems to have the ability to reject disturbances and generate parametric insensitivity features, proportional-plus-integral (PI) control is still regarded as the industry standard. Prolonged persistent research in SMC [such as its transition to second-order sliding mode (SOSM)] is always in place; however, comparatively, its market penetration in shaping up a complete established industrial product is far below expectation. The absence of a support system in the form of very large scale integration circuits to translate its control function for actuation increases the design cycle time that adds to inertia to its market penetration. Second, implementing SOSM is not simple either. Is there any other reason? This paper, using a purely practical approach operating on respective proven control functions, tries to figure out how PI dominates over SOSM ideas in shaping up a complete market-driven engineered product for a multiple-input multiple-mode complex and yet most popular arc welding (gas metal arc welding) process, where disturbances and parametric variations are thick and large.