Decentralized nonlinear control strategies for disturbance rejection in winding systems

In winding and web transport systems, which are complex and large scale interconnected dynamics systems with a demand for increasingly high level of performance, the objective is to ensure quality processing and rewinding of the product. A major problem in controlling such systems is that disturbances propagate through the system and affect both velocity and tension loops because of the strong mechanical couplings. An active disturbance rejection control (ADRC) strategy and a nonlinear PI (NPI) controller are proposed and compared with PI control to improve the overall performance of the system, i.e. increasing dynamic tracking precision, reducing rise time for step input and furthermore improving robustness to the change of the web stiffness during the winding process. Simulation results of an industrial application show the effectiveness and disturbance rejection properties of the proposed controllers in coping with large dynamic variations commonly seen in web handling applications.