Research On Backstep Ping Sliding Mode Control Of Speed Tension And Screwdown System Of Reversible Cold Strip Mill

The reversible cold strip mill has the characteristics of simple structure,low investment and low operating cost,and it is suitable for small batch production of different strip steel product specifications.In the actual rolling production process,the left coiler,electro-hydraulic servo system,the main mill and the right coiler of the reversible cold strip mill are connected by a flexible connection of strip steel,and the characteristics of speed tension and screwdown system of the cold strip mill is multivariable and nonlinear,strong coupling,uncertainty and slow time-varying.,and the constraints of the main drive maximum acceleration and deceleration,heavy load and interference in the rolling process pose new challenges to the analysis and control of the rolling mill system.This paper focuses on the backstepping sliding mode control of the study of the speed-tension and screwdown system of the reversible cold strip mill.The main research work is as follows:Firstly,combinning with the rolling production process of cold-rolled strip,based on Hooke’s law,relevant rolling theory of cold-rolled strip,motor dynamics equation,rigid body rotation law,hydraulic cylinder force balance equation and other basic theoretical knowledge derive Mechanism model of speed tension and screwdown system for reversible cold strip mill.Secondly,aiming at the position tracking control problem of the asymmetric cylinder electro-hydraulic servo system of the main rolling mill with input saturation,an adaptive dynamic surface backstepping control method based on fuzzy disturbance observer is proposed.The method constructs a fuzzy disturbance observer to observe and estimate the composite interference composed of parameter perturbation,load disturbance and beyond the control input limiting part,and introduces the output observation value into the designed dynamic surface backstepping controller as compensation,which is implemented to effectively enhance the anti-jamming performance of the system and simplify the design process of the system controller.Thirdly,aiming at the coordinated tracking control problem of the speed tension system of reversible cold strip mill,a backstepping sliding mode control strategy based on tracking differentiator(TD)is proposed.Based on the backstepping method,the design of the sliding mode controller of each subsystem of the reversible cold strip mill speed is completed,which effectively improves the coordinated tracking control performance and robust stability of the system.The virtual control law and its derivative are estimated by TD.The "differential explosion" problem existing in the conventional backstep is avoided,and the structure of the designed controller is optimized.Finally,aiming at the adaptive robust control of the speed tension and screwdown system of reversible cold strip mill,an observer-based fractional backstepping sliding mode control method is proposed.The method constructs a finite-time convergence observer to observe the disturbances such as uncertainty,and combines the backstepping control with the fractional-order sliding mode to complete the design of the controller of each sub-system of the speed tension and screwdown system of the reversible cold strip mill.The PSO optimizes the main parameters of the designed controller,fully exerting the control potential of the proposed method,and improves the adaptive performance of the control system.