Robust GMV cross directional control of paper machines

This paper considers the cross directional (CD) control of web manufacturing processes, such as in paper machines. In particular, it proposes a practical method for regularizing control of poorly controllable modes of the CD profile, while preserving the attenuation of the disturbances for the well controllable modes. A multivariable generalized minimum variance (GMV) controller is introduced. The GMV penalties are chosen so that the controller is robust to model identification errors and satisfies constraints on the size of the control action. The resulting feedback controller is an extension of the well-known Dahlin regulator. This controller has a familiar form including an actuator profile smoothing term, which is encountered in many industrial CD control systems, but was not analyzed in prior theoretical papers on the subject. The proposed design procedure is illustrated by designing a controller using data from a real paper machine.