Shape control systems for Sendzimir steel mills

This paper deals with the problem of shape (or flatness) control for Sendzimir 20-roll cold-rolling steel mills. Such mills, with a variety of shape actuators, offer the control engineer considerable choice in the configuration and design of a shape control system. In addition, the Sendzimir mill is a reversing mill, with shape measurement devices at either end of the mill, providing a facility for feedforward of incoming shape disturbances. The multivariable problem presented by the mill has a significant singularity problem, which is tackled in this paper using a variety of approaches, motivated by both practical (operational) considerations and formal theoretical procedures. A final challenge lies in the desire to economize on the number of controllers required to cover the mill over its wide range of operating conditions. The paper compares and contrasts various controller possibilities and is intended to provide a “cookbook” of shape control tools and strategies for Sendzimir mills