Equivalent Fuzzy Sliding Mode Control of the Web Tension in Unwinding System

The unwinding system is the front part of the roll-to-roll manufacturing process, in which the control accuracy of the web tension has a huge effect on the manufacturing accuracy and product quality. Sliding mode control (SMC) method is widely used in web tension control to solve the disturbance caused by the radius variation of the unwinding roller. However, it is difficult to avoid the system chattering problem by using the general equivalent Sliding mode control (ESMC). In this paper, the mathematical model of the web tension in unwinding system is established by analyzing the longitudinal dynamics of the web. Then a new equivalent fuzzy sliding mode control (EFSMC) method is proposed to solve the chattering problems. The simulation experiment is carried out to compare the performance of the web tension control with ESMC and EFSMC method. The simulation results show that the EFSMC method has nice dynamic performance and tracking accuracy of the web tension control. The chattering problem caused by the web velocity variation can be effectively attenuated. The EFSMC method also shows good performance on the disturbance rejection of the web tension.

1 Introduction

Tension control is one of the indispensable issues in the flexible web winding and conveying system (FWWCS). Accurate tension control ensures the quality of flexible web and improves the efficiency of production [1]. In this paper, the flexible web unwinding tension control system is taken as the research object. Because it is a nonlinear, strongly coupled, and time-varying complicated system, thus establishing an accurate mathematical model of the tension system is the prerequisite of designing a suitable controller and applying advanced control method.