Research On Active Disturbance Rejection Control Strategy For Hydraulic Servo System Of Cold Rolling Mill

The hydraulic servo system is the executive part of the entire cold-rolling unit plate thickness control system,which directly affects the final quality of the cold-rolled strip.In the actual industry,the internal parameter perturbation and the external load disturbance in the hydraulic servo system model will cause errors in the hydraulic cylinder depressing position on both sides of the rolling mill,and the problem of synchronous control cannot be realized.This paper selects a kind of auto-disturbance rejection controller which is not based on mathematical model and has strong anti-interference ability to control the hydraulic servo system,which greatly reduces the position error on both sides of the rolling mill.For the problem that the coupling parameters of the nonlinear auto-disturbance-rejection controller are difficult to set,an on-line tuning method based on the intelligent optimization algorithm is studied.In addition,in order to solve the problem of the observer's poor ability to observe the random multi-source disturbance,an adaptive extended state observer is designed.The main work of this article is as follows:(1)Aiming at the problem that the parameters of the nonlinear auto disturbance rejection controller are difficult to adjust so that the control precision of the hydraulic servo position system is affected,the shark optimization algorithm is used to set the controller parameters online.However,the algorithm is easy to trap into the local optimum,slow optimization and even stagnation during the iteration process,cross-mutation and double-population strategy are introduced to improve the algorithm and improve the global search ability of the algorithm.The single-side hydraulic servo system of the cold rolling mill was used as the controlled object.It was verified that the improved shark optimization algorithm had better control accuracy and anti-disturbance capability than the other optimized optimization auto-disturbance rejection controller and improved the hydraulic pressure effectively.In addition,the dynamic performance of hydraulic servo system has also been effectively improved.(2)For a class of multi-source stochastic perturbations encountered in the cold rolling process,a problem of the traditional auto-disturbance rejection controller cannot be observed,a class of adaptive extended state observers is proposed.Firstly,a mathematical model of stochastic disturbance is established according to the source of disturbance.By combining the adaptive term and the extended state observer,an adaptive extended state observer is deduced.Besides,it combined with the state feedback control rate to construct a new auto disturbance suppression control structure.Second,based on the Lyapunov function,the stability of the proposed controller was verified.Finally,it is verified that the proposed adaptive pile-expanded state observer can observe and compensate for random multi-source disturbances through simulation.(3)Aiming at the problem of non-synchronization of hydraulic position servo pressure on both sides of the rolling mill,the nonlinear hydraulic cylinder model was studied.A non-linear auto-disturbance disturbance position controller and a non-linear auto-disturbance disturbance position adjuster were designed to observe the errors on both sides and give eliminating,in the final case of ensuring that the pressing position is synchronized,the system has higher dynamic characteristics and speeds up synchronization.Simulation experiments show that the proposed scheme can achieve rapid synchronization of hydraulic cylinders on both sides of the rolling mill.