Robust tension control in papermaking

Material such as paper, plastic film and textiles are most economically manufactured or processed in the form of a web. There is a need to improve accuracy of the tension control of the web, especially accurate tension control in a moving web.; Firstly, Model reference adaptive control designs using MIT rule and proportional integral adaptive methods to yield the control parameter adjustment mechanism are detailed in this thesis. Lyapunov techniques are used to develop a model-reference control system that exponentially stabilizes the material tension at desired setpoints. A novel model of changing the length of spans by employing magnetic bearing is developed to allow fast and accurate adjustment of tension in the web.; Secondly, Regulating tension in multi-span web systems is also investigated using Hinfinity control. mu synthesis is employed to construct the controller so that the closed-loop system remains stable for a range of possible plant uncertainties and disturbance inputs. Controller order reduction is achieved to make the designed controller more practical for industrial use.; Simulation results compare the tension setpoint regulation provided by the proposed control strategy with PID tension feedback control and showed that the Hinfinity controller with guaranteed robustness performed comparably in disturbance rejection to the other controllers. This work summaries conditions for controller selection.