Robust Decoupling Control Of The Hydraulic Looper Multivariable System

The guarantee of modern hot rolling mill is constant looper and tension.In the rolling process, owing to dynamic speed drop and external disturbance, it is difficult to maintain speed matching relationships between all stands. We need to build looper system to detect the deviation and absorb the looper height caused by speed deviation changes to maintain the small tension.The article makes a detailed study of the hydraulic looper height and tension system based on 1700 ASP. The main research contents and outcomes are presented as follows:Firstly, the hydraulic looper system has the features of nonlinearity, strong coupling, uncertainty, and multi-constraints. In this paper, a dynamic mathematical model of the hydraulic looper system is set up at the vicinity of the working point, and get the hydraulic looper system state equation, then work out the transfer function and discrete. So the decoupling control is presented in this paper.Secondly, the PID is applied the created mathematical model of the hydraulic looper coupling system to decouple the system model and prove the control effectiveness. The results of the simulation show the effectiveness of this method, but the weakness of anti-interference and decoupling response is shown. So, this paper proposes Robust decoupling control algorithm, and the algorithm is applied to the hydraulic looper height and tension coupling system. The robust controller model is designed by the small gain theory, and the hydraulic system gets the optimal Robust controller model to achieve the effects of decoupling control through weighed items for calibration and optimization of controller parameters. The simulation results show the effectiveness and reasonable.Finally, aiming at the parameter perturbation of the coupling control system, this algorithm makes the coefficients of weighed function items fluctuate in a certain scope to focus on the hydraulic looper coupling system. The simulation results have indicated that it is remarkable that the output of the hydraulic looper coupling system effect, decoupling the response speed and anti-interference ability are the nearly same as robust decoupling control when the coupling system has parameter perturbation.