Looper angle and looper tension control between roll stands in hot strip finishing mills in adaptive, predictive Proportional Integral (PI) and Inverse Linear Quadratic (ILQ) control modes, with activation by means of servo valves and hydraulic cylinders

Abstract

In this article, the development of parameterization of the controller for looper control angle and tension in hot strip finishing mills is traced based on Inverse Linear Quadratic (ILQ) and Proportional Integral (PI) mode control, mainly considering, in the rolled material, thickness and width in the steel strip. Firstly, the ILQ mode approach is applied in the looper angle and looper tension, both calculated and compared with real conditions, to compensate disturbances and unmodeled dynamics in the looper, increasing or decreasing the angle position, through of Automatic Pressure Control (APC) as well as the speed reference in the previous stand rolling. Secondly, the Proportional Integral (PI) mode approach is applied in the looper angle e looper tension, where only looper angle is calculated and compared with the real condition and looper tension is calculated and applied in the open loop with use torque reference, to compensate disturbances and unmodeled dynamics in the looper. So, one set of ideal control parameters has been defined for the looper tension and looper angle, improving the performance of the overall system, always depending on the processed material, and thickness and width in the steel strip in the finishing mill. Simulation results show the effectiveness of the proposed controller compared with other methods that use only one control model for all steels’ types.