Optimum Feedback Controller Design for Tandem Cold Metal Rolling

Abstract Controlling the tandem cold rolling of metal strip is a significant challenge to the control engineer. This is due mostly to complex interactions between the process variables, nonlinearities that change with process conditions, and long speed-dependent time delays. The present technology is limited in its capability for improvement in performance. This paper describes a new control strategy that is based on solving a state-dependent algebraic Riccati equation pointwise to establish a control law for a MIMO controller that is augmented by appropriate trimming functions. Simulation testing showed that the tolerance in mill exit thickness compares favorably to the tolerances using existing techniques.

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