Research On Control Method Of Valve Controlled Cylinder System Based On Parameter Identification

In recent years,new ideas,new theories and new technologies formed by the integration and development of multiple disciplines have been widely used in the field of hydraulic technology.The control problem of electro-hydraulic servo system is one of the research hotspots of many scholars.As an important branch of electro-hydraulic servo system,the improvement of control performance of valve-controlled cylinder system has important practical significance.However,due to the strong nonlinear characteristics of the valve-controlled cylinder system itself and the inevitable influence of time-varying parameters,modeling errors,loads and external disturbances in the control of the system,the dynamic control accuracy is low.In view of the above problems,it is necessary to design a controller with good performance.Therefore,this paper studies from three aspects :modeling,identification and control.The online identification theory(recursive least squares method)is introduced to obtain the state space model parameters of the valve-controlled cylinder system,and a backstepping control strategy based on parameter identification is proposed.With the help of the joint simulation platform,it is proved that the adopted identification method has more accurate identification accuracy and the effectiveness of the proposed control strategy.The specific research work and conclusions are as follows:(1)Firstly,the dynamic characteristics of the valve-controlled cylinder system were analyzed,and the mathematical model of the power mechanism of the valve-controlled cylinder system was established.The appropriate state variables were selected to determine the identification model of the valve-controlled cylinder system.Secondly,the system identification theory and the least squares theory were introduced.Finally,the recursive least squares identification algorithm in the form of multi-dimensional matrix of the valve-controlled cylinder system was derived.(2)The co-simulation platform was introduced,the purpose of co-simulation was discussed,and the recursive least squares identification algorithm program based on high-level C language was developed.Based on the co-simulation platform,the parameter identification simulation experiment of the valve-controlled asymmetric cylinder system was designed,and the online estimation of the model parameters of the valve-controlled asymmetric cylinder system was completed.The simulation results show that the recursive least squares algorithm can accurately estimate the system model parameters and provide reliable model parameters for subsequent controller design.(3)According to the principle of backstepping control,the control model of valve-controlled cylinder system with strict feedback form was established,and the backstepping controller of valve-controlled asymmetric cylinder system based on parameter identification was designed.In order to verify the control effect of the designed controller,compared with the conventional PID control,the PID control of the valve-controlled asymmetric cylinder system and the backstepping control model based on the joint simulation platform were built.The simulation results show that the backstepping controller based on parameter identification has higher control accuracy and response speed,which verifies the feasibility and correctness of the backstepping control strategy based on parameter identification.