Research On Robust Decoupling Control Of Cold Rolling Shape And Thickness Integrated Coupled System

Shape and thickness are important measures of strip quality.However,in the plate shape and thickness integrated system,the plate shape control affects the plate thickness control,and the plate thickness control also affects the plate shape.The plate shape and thickness system is a non-linear system with strong coupling.Therefore,a control strategy is needed to be proposed to realize the decoupling and control of the plate shape and thickness.Aiming at the problem of the coupling relationship between the plate crown and thickness,a mathematical model of plate shape and thickness coupling based on the change of the roll gap and the bending force as inputs and the change of the plate thickness and the plate crown as the outputs was built.A robust control method based on feedforward decoupler was proposed.The feedforward compensation decoupling method was used to decouple the system to obtain two sets of single-input and single-output systems in approximate forms.The robust ?H controller was designed to control the decoupled system,which was simulated and analyzed and compared with PID feedforward decoupling control.The results show that the decoupling effect of the robust feedforward decoupling control strategy is better than that of PID feedforward decoupling control.In contrast,the response time of robust feedforward decoupling control system is reduced by 0.3-0.5s.When the system model parameter such as G11 is perturbed by ± 5%,the dynamic response system performance is still good.Considering the four-input and four-output model of the coupling between the plate shape control,the plate thickness control and the front and rear rack tension,a inverse system theory was used to design a neural network inverse decoupler based on fuzzy clustering to realize the linear decoupling of the coupled model of cold tandem rolling.A neural network equivalent sliding mode controller based on immune cloud particle swarm optimization was designed to have closed-loop control over the decoupled system.The results show that this controller has a good tracking effect and robustness.Compared with the PID controller,the equivalent sliding mode controller reduces the response time by about 0.3s and the overshoot by at least 50%.When the system parameter Q is perturbed by ± 5%,the system can maintain stable operation.