The design of strip shape control systems for Sendzimir mills

A multivariable design technique is described for use in the design of strip shape control systems. The main control problem stems from the uncertainty in the knowledge of the mill gain matrix. The effect of modeling errors is to introduce interaction into the imperfectly compensated system. The design technique involves squaring down the system to make it more robust in the presence of such errors. The approximately upper triangular form of the transformed system enables a simple precompensator to be designed and the system is shown to be stable over a wide range of line speeds.