Width control approach of finishing strip mills based on improved generalized predictive control

In order to increase the rate of qualified products and the precision of strip width in a continuous hot strip mill, a width gauge is usually set behind the last finishing roll stand. The purpose of adjusting strip width can be attained by changing the tension of stands. Since there is a long distance from the last finishing roll stand' s central line to the width gauge, the system is usually a large time-delay and time-variation one; as a result, it is difficult to build an accurate model. An improved generalized predictive control method was proposed which has fewer requirements for modeling and can adaptively adjust the controller's parameters based on generalized estimate errors. The controller's parameters were identified directly without solving the Diophantine equation or the inverse of matrices, and the online computing time was shortened, which makes the approach be very suitable for the fast rolling process. Simulation results showed the method's validity especially for a large time delay and complex system such as width control during finishing rolling.