Position controller tuning of an intermittent web transport system using off-line identification

Mathematical modeling as well as design of proper process controllers for web handling systems requires knowledge of the system dynamics or observations from an actual system. The dynamic behaviour of a web handling system is defined by the interactions between a flexible web, rollers and electric drives. In this paper, offline-identification of a web transport subsystem is considered. The identification of the system is carried out by exciting the controlled system with a pseudo-random binary signal (PRBS) as torque reference. A discrete time polynomial model with an Output-Error (OE) structure is used in the time-domain identification process. Moreover, this paper investigates the tension and position controls of an intermittent web transport system. The position controller of the system is designed for the identified and reference system model with H_∞-loop shaping. Validation of the controller design and the influence of the model improvement are verified through experimental tests.