Distributed Coordinate Tension Regulation of Web Processing Systems With Two Unwinders

This article presents a distributed coordinate tension regulator for web processing systems with two unwinders in presence of changes of production speed. First, each system input is divided into the equilibrium control input and control compensation, and the distributed variation model around the dynamic equilibrium points is obtained by Taylor expansion in presence of changes of production speed. Then, the problem of tension regulation is transformed into the stabilization of distributed variational system. Next, the interval variables are introduced to denote the changeable desired outputs and the system uncertain or time-varying parameters, and then an interval matrix-based distributed coordinate tension regulation strategy is proposed by choosing appropriate coordinate variables. Subsequently, existence conditions of proposed distributed coordinate tension regulator are obtained via the Lyapunov theory. The designed regulator is obtained by solving the linear matrix inequalities with few adjustable parameters. Finally, the comparison simulation is conducted on a five-motor-driven system to validate the effectiveness and control performance of the proposed method.

I. Introduction

Web processing systems with two unwinders have been widely used in the manufacturing fields of textile, printing, and disposable medical mask [1]–[3]. This kind of systems consists of a group of motor-driven rolls, such as unwinding roll, lamination and speed traction roll, processing roll, and rewinding roll. These rolls are connected through webs, and the web transportation is realized by the friction between web and roller shaft. During the system operation, two different webs are released from two unwinding rollers to the lamination and speed traction roll to form a composite web. Then, the obtained composite web is transported via the processing roll and accumulated on the rewinding roller [4]. Due to the continuous operation of web processing systems, the final product quality is not only affected by variations at a local operation step but also by variations transferred from upstream operations [5]. Hence, an appropriate control input should be designed for each motor-driven roll to minimize adverse effects of tension tracking errors for all operations, assuring the product quality and reducing the productivity loss.