| In recent years,with the rapid development of automobile manufacturing,aerospace,instrumentation,power electronics and food packaging industry,the demand for metal sheet and strip has been greatly promoted.At the same time,the strip users have higher and higher requirements on the dimensional accuracy,surface quality and mechanical properties of the strip.In the process of high speed strip rolling,the rolling mill vibration often occurs due to the change of rolling conditions.The rolling mill vibration will not only affect the product quality,but also contain potential huge accidents.Therefore,the vibration problem is the bottleneck problem that restricts the development of rolling towards high speed and high precision.In this dissertation,based on the results of field vibration test,the performance constrained vibration control strategy of strip rolling process is studied.The main research works are summarized as follows:(1)The rolling mill vibration test system is constructed,and the rolling mill vibration test is realized.By processing the vibration signals and rolling vibration parameters,the rolling mill vibration test results are analysed.The results show that: 1)rolling speed is more than 900 mpm,rolling mill is prone to vibration;2)rolling mill mainly has three vibration forms of vertical vibration,torsional vibration and vertical torsional coupling vibration;3)the greater the steel strength,the stronger the rolling mill vibration,so it is necessary to limit the rolling mill vibration;4)the vibration source of the rolling mill is located at the roll gap of the rolling mill.At the same time,the influence of different technological factors on the vibration of rolling mill is analysed.(2)Aiming at the problem of sensor measurement error,a state feedback control strategy with prescribed performance for torsional vibration of main drive system is studied.Considering the nonlinear friction between roll gaps,the nonlinear model of torsional vibration of rolling mill is established.The unknown parameters caused by sensor error are estimated by introducing the adaptive boundary method.The design steps of controller are simplified and the calculation explosion problem is solved by using dynamic surface technology.Based on asymmetric prescribed performance conversion and Lyapunov stability criterion,an adaptive torsional vibration control strategy for rolling mill drive system based on performance constrained and sensor errors is proposed,and the effectiveness of the control strategy is verified by simulation.(3)Aiming at the problems of state and input constraints of the main drive system and the sensor error,the adaptive neural network performance constrained control strategy of main drive system is studied.Considering the nonlinear friction between roll and strip,the nonlinear damping of motor and load and the unknown and uncertain system parameters,the nonlinear torsional vibration model of rolling mill is established.The adaptive neural network is used to deal with the unknown system uncertainty and the unknown sensor measurement error,and the Gaussian error function is used to solve the actuator saturation problem.Based on the barrier Lyapunov function and backstepping method,an adaptive neural vibration control algorithm for rolling mill drive system based on state and input constraints is designed to ensure the whole state transient-steady stability constraint performance of the system.(4)Aiming at the problems of dead zone and output constraints in vertical vibration system of rolling mill,the control strategy of vertical vibration suppression is studied.Considering the equivalent force between the backup roll and the hydraulic cylinder and the uncertain nonlinear rolling force,the vertical vibration model of the mill is established.The adaptive fuzzy logic system is used to deal with the unknown nonlinear functions and system parameters.Based on the asymmetric tangent barrier Lyapunov function and the backstepping method,an adaptive fuzzy control strategy for vertical vibration suppression of the rolling mill is proposed.The stability of the system is proved by theoretical method and simulation experiment.(5)For the electromechanical hydraulic vertical torsional coupling system of rolling mill,the control strategy of vertical torsional coupling vibration with output limitation is studied.Considering the coupling effect between the main drive system and the roller system,a new electromechanical hydraulic vertical torsional coupling vibration model is established.The asymmetric Barrier Lyapunov Function is used to ensure that the output of the vertical torsional coupling system meets the given index.Based on the specific sequence backstepping method,a vibration control strategy for the electromechanical hydraulic vertical torsional coupling system is proposed,which avoids the loop nesting problem of controllers.Finally,the effectiveness of the algorithm is verified by simulation. |
