Progress in Development of a Control Model for a Tandem Hot Metal Strip Rolling Process

The tandem hot metal strip rolling process is a highly complex nonlinear system that presents a difficult control challenge. This challenge is exacerbated by the hostile hot metal rolling environment which precludes the location of sensors to measure variables that are important for control. In addition, the controller must have a structure that offers a high degree of physical intuition in the design process, plus the simplicity of tuning during commissioning by personnel who in general are unfamiliar with advanced process control techniques. Based on our previous work using a state-dependent Riccati equation technique for control of the tandem cold metal rolling process, it is considered that a similar method also might be useful as a basis for the development of a control technique for tandem hot strip rolling. For the hot rolling process, the development of a process model in a form that is suitable for use with a state-dependent Riccati equation-based method is a significant and challenging task. This paper describes our work to expand on an initial portion of this model to develop a comprehensive nonlinear model of this process. Based on simulation results, it is determined that the complete model has the potential to be useful in the development of a viable nonlinear control method which offers the likelihood for significant improvement in the control of the entire process. Keywordsmulti-input-multi-output control; tandem hot metal rolling; rolling mill control; state-dependent Riccati equation