Robust Tracking Control Research For Continuous Casting Mold Vibration Displacement System Driven By Servo Motor

The mold is the core equipment in the process of continuous casting production,and its vibration mode has important effect on casting surface quality.There are several uncertainties existing in vibration control system of continuous casting mold driven by servo motor have great influence on mold vibration displacement tracking precision.Therefore,taking the servo motor driven continuous casting mold vibration displacement system as the research object,the controller design and simulation research is carried out for the mold displacement tracking problem.Firstly,the general mathematical model of mold vibration displacement system driven by servo motor is given,aiming at the nonlinear periodic function existed in the forward channel of model,a kind of mapping function is proposed to establish one-to-one mapping function relationship between eccentric shaft angle and mold displacement,and a sliding mode controller is designed to verify the feasibility of the mapping function.At the same time,it is pointed out that the uncertainty of the system has a great influence on the performance of the control system.Secondly,active disturbance rejection control(ADRC)is applied to solve the problems of time-varying load torque disturbance,reduction ratio uncertainty and the initial deviation of the eccentric shaft mechanical zero,which exist in the continuous casting mold vibration displacement system driven by servo motor.By tracking differentiator,extended state observer(ESO)and nonlinear state error feedback law,comprehensive disturbance is estimated and compensated,the simulation show ADRC enhances system anti-disturbance ability.Thirdly,a nonsingular terminal sliding mode(NTSM)controller based on ESO is designed.The ESO is designed for the displacement subsystem to estimate the comprehensive disturbance existing in the system.Then the disturbance observer is introduced into the NTSM controller to compensate,which enhance the system’s tracking accuracy and anti-jamming ability,and the effectiveness of the controller is verified by simulation.Finally,considering the uncertainty,load disturbance and unmeasurable state in the system,an adaptive sliding mode control method based on ESO is proposed.ESO is used to estimate the comprehensive disturbance and unmeasurable state of the system,and then a layered design structure is used to design the NTSM controller and sliding mode controller for the displacement tracking subsystem and the current loop system respectively.In the design of the NTSM controller,the adaptive sliding mode term is introduced,and the adaptive gain is used to estimate the unknown terms that contain the upper bounds of the error of the ESO estimation.Simulation results show that this method can effectively improve the accuracy and response speed of the mold displacement.