Looper Angle Research Articles

Inferential control for rolling mills

A robust inferential controller is developed for hot strip rolling mill tension control. Tension cannot be measured, therefore a nonlinear model is used to infer the tension from the looper angle. The model uses constant physical parameters while the actual physical system will be uncertain, therefore quantitative feedback theory is used to design a tension controller, which will provide robust performance despite uncertainty from both the physical system and the inference model or soft sensor.

Robust inferential control for hot strip mills

An robust inferential controller is developed for hot strip rolling mill tension control. Since tension cannot be measured a non-linear model is used to infer the tension from the looper angle. Since the model uses constant physical parameters and the actual physical system will be uncertain then Quantitative Feedback Theory is used to design a tension controller which will provide robust performance despite physical system uncertainty and uncertainty in the inference model or soft sensor.

Optimal control system for hot strip finishing mill

This paper describes how to control the strip gauge, looper angle, and strip tension for a hot strip finishing mill, and gives the results of a real application. This is based on optimal servo theory and the model decoupling method. In the finishing mill process, there exists a mutual interaction among the strip gauge, the looper angle, and the strip tension. Conventionally, each of them is controlled independently. To improve the control performance, multivariable control that considers this interaction is applied to the whole productions process. The new control system is also used for the tension control of the automatic width control.

Controller design for hot strip finishing mills

The results to date of a collaborative research project with BHP Steel in Port Kembla, Australia, are described. The project is concerned with control of strip tension and looper angle in BHP's hot strip steel rolling mill (the finishing mill). The new controllers have been successfully implemented on the process and now handle all the production at the mill. The paper describes a model of the process, similar to that reported in the work of others. The development of a full nonlinear controller is traced, based on a recursive nonlinear method (cf., backstepping). Insights are drawn into possible system structures, particularly in the output feedback case when tension measurements may not be available. Alternative controller schemes are examined, including a speculative design which contains filters, similar to those obtained from output feedback designs of linear systems, together with nonlinear operators which invite comparisons with variable structure designs. Simulation results, which provided the justification for the final implementation, together with results from actual production records are presented.

Adaptive Fuzzy Regulation of Strip Tension and Looper Angle in Hot Finishing Mill

ABSTRACTThis paper presents an adaptive fuzzy controller with feedback linearization and switching control technique that is used to regulate the tension of steel strip and the angle of looper system that exist between stands of the hot finishing mill. Each control loop in the proposed controller adopted an adaptive fuzzy logic structure which is reported to be superior in performance to the neural network techniques. The adaptive fuzzy controller is robust due to its fuzzy representation of the controller and is adaptive due to its training capability. The feedback linearizing control term improves control performance particularly in the transient behavior, whereas the switching control term compensates for the inevitable model approximation error incurred by the fuzzy logic representation. Combining all these terms, the proposed controller is asymptotically stable with robustness in the adaptive fuzzy controller.

Optimal Control System for Hot Strip Finishing Mill

This paper describes how to control strip gauge, looper angle, and strip tension for a hot strip finishing mill and the application result. This is based on the optimal servo theory and the model dccoupling method. In finishing mill process, there exists mutual interaction among strip gauge, Iooper angle, and strip tension. Conventionally, each of them is controlled independently. To improve the control perfonnance, the multivariable control considering this interaction is applied to all productions. The new control system is also used for the tension control of the automatic width control.

Optimal Control System for Hot Strip Finishing Mill

This paper describes how to control strip gauge, looper angle, and strip tension for a hot strip finishing mill and the application result. This is based on the optimal servo theory and the model decoupling method. In finishing mill process, there exists mutual interaction among strip gauge, looper angle, and strip tension. Conventionally, each of them is controlled independently. To improve the control performance, the multivariate control considering this interaction is applied to all productions.

外乱オブザーバを用いた熱延仕上圧延機のルーパ多変数制御

A looper multivariable control with a disturbance observer was developed at the Hot Strip Finishing Mill of Kashima Steel Works. The new looper multivariable control consists of the following two controls which are designed so as to simplify its construction. The one is the feedforward control based on the disturbance observer which compensates for the strip tension fluctuation and looper angle fluctuation caused by the screw down position adjustments of AGC (Automatic Gauge Control). The other is the state feedback control of the strip tension and the looper angular velocity which is designed based on the pole assignment method and improves the performance of the strip tension control and the looper angle control.The superiority of the new looper multivariable control was proved by the simulation and experimental results. The new control has been in operation since July in 1994 and improved the control performance of the strip tension and looper angle at Kashima Hot Strip Finishing Mill.

Interpolated Control of Looper Hight for Hot Strip Mills

We describe a new control system which stabilizes a looper angle variation caused by rolling disturbances. After estimating the damping coefficient of looper system, this system determines the PI controller gain based on interpolated controller scheme. Experimental results show the usefulness of the proposed method

Optimal multivariable looper control for hot strip finishing mill

An optimal multivariable looper control system based on optimal-regulator theory was developed for hot strip finishing mills. Loopers of a hot strip finishing mill are installed between stands and are, in many cases, driven by motors. The goal of looper control is to maintain product quality at a high level by stabilizing the rolling operation. Stability is achieved by keeping the looper angle and tension applied to the strip at given reference values. The most difficult problem is mutual interaction in the simultaneous control of looper angle and strip tension. In particular, increasing use of low-temperature heating of slabs, high-carbon steels, and high-speed rolling places additional demands on the looper control system. Moreover, high quality of thickness, width, and crown are strongly requested. Controlling the rotational speed of the looper motor in addition to the existing looper motor current control has allowed a robust looper control system that can cope with changes in rolling conditions. Based on the current rolling conditions, the system selects the control gain calculated from different weight matrices for the linear quadratic criterion. The developed control system can maintain relatively constant strip tension without operator intervention in the presence of rapid changes of hydraulic screwdown, such as automatic gage control (AGC) operation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Looper optimal multivariable control for hot strip finishing mill.

A looper optimal multivariable control system based on an optimal regulator theory has been developed. Goal of controlling the hot strip finishing mill loopers is to stabilize rolling operation and to maintain product quality by controlling the tension applied to the strip and the looper angle within their reference values.The most difficult problem in looper control is to achieve simultaneously the interfering tension control and looper angle control. In recent years, a non-interactive control employing cross-controllers has been adopted and brought a dramatic increase in control accuracy, although the response time is limited. Thus, a new method with improved response time is desirable.In this paper, a looper optimal multivariable control based on the optimal regulator theory employing a looper drive system with speed control loop is proposed. Other topics discussed includes the results of an investigation of simplifying the control system by the use of a programmable controller. In addition, it is demonstrated that the optimal multivariable control is effective compared with the conventional control and the non-interactive control as employed in the hot strip finishing mill of Hirohata Works of Nippon Steel Corporation.