Robust Decentralized $H_\infty$ Control for a Multi-Motor Web-Winding System

To deal with the nonlinear coupling, strong disturbances and parametric uncertainties existing in the multi-motor web-winding system, a robust decentralized
$H_\infty $
control method is proposed in this paper. First, the whole web-winding system is considered as a synthetic system composed of several subsystems. Giving that some parameters are time dependent and set points are modified during the winding process, each subsystem can be seen as a dynamic interval system and interval matrix is introduced. Then, a robust decentralized
$H_\infty $
controller is designed to attenuate tension fluctuations introduced by the external disturbances and interaction between two consecutive subsystems. Sufficient condition for the existence of robust decentralized
$H_\infty $
control law is presented in terms of linear matrix inequality. Finally, some simulations and experiments are conducted with the conventional decentralized controller and the proposed controller. The comparative results show that the proposed control scheme greatly improves the control performance of the web tensions.