Iterative Learning Conttol For Vibration Displacement System Of Continuous Casting Mold Driven By Servo Motor

Continuous casting mold is the key equipment in continuous casting production.Whether the mold can vibrate up and down according to the given vibration waveform plays an important role in improving the surface quality of slab.The mold moves repeatedly under the periodic vibration law.For the controlled object with the characteristics of repetitive operation,iterative learning control can realize the complete tracking of the expected trajectory in a limited time.However,in the process of system operation,the motor parameter perturbation,external random disturbance and other non-periodic disturbance will have a great impact on the actual vibration displacement of the mold,resulting in the decline of the surface quality of the slab.Therefore,this paper takes the vibration displacement system of continuous casting mold driven by servo motor as the research object,and designs robust iterative learning control algorithm to improve the tracking performance of the system.The experiment is conducted through MATLAB simulation and an experimental platform based on SIMOTION D425.The main work arrangement is as follows:Firstly,the approximate mathematical model of the servo motor and the mechanical transmission mechanism is derived,by analyzing the overall structure and working principle of the vibration displacement system of the continuous casting mold driven by the servo motor based on SIMOTION D425,which combined with the existing experimental platform in the laboratory.At last,the mathematical state space expression of the system is sorted out.Secondly,according to the characteristics of the uncertainties in the system,the comprehensive disturbances such as reduction ratio error,load disturbance and clearance and friction of the mechanical transmission are divided into periodic disturbance and non-periodic disturbance.For the continuous casting mold vibration displacement system with periodic disturbance and non-periodic disturbance,a backstepping sliding mode iterative learning control algorithm is proposed.The iterative learning controller is designed by using partial limit learning law to estimate the periodic disturbance,and the estimated value is introduced into the controller for compensation,The non-periodic disturbance is suppressed by combining backstepping control and sliding mode control,which is further improved the robustness of the system.Finally,the effectiveness of the control algorithm is verified by MATLAB simulation and the experiment platform based on SIMOTION D425.Finally,a compound control algorithm of feedforward + iterative learning control is proposed for the vibration displacement system of continuous casting mold driven by servo motor with repetitive motion and nonlinear periodic function.For periodic given signal,the expected speed of servo motor is given as feed-forward control through mechanism analysis;In order to improve the robustness and convergence rate of the system,the PID type iterative learning controller with forgetting factor is designed,and the convergence of the system is proved by compression mapping method;.Finally,through MATLAB simulation and experiment platform based on SIMOTION D425,the control algorithm with negative exponential variable forgetting factor has better comprehensive performance in convergence accuracy and convergence speed...