Research On Semi-physical Simulation Method Of Valve-controlled Cylinder System Based On Linux Real-time Kernel

The dynamic control performance of valve-controlled cylinder system is always a hot issue in hydraulic servo field.When the designed controller is used to control the actual valve-controlled cylinder system,its feasibility and security must be tested comprehensively through simulation verification and real experiment.Due to the inability to simulate physical experiments in extreme situations,certain safety hazards in experimental operations,and high cost of experimental equipment,the controller cannot be fully validated.At the same time,the credibility of pure mathematical simulation is poor.Therefore,domestic and foreign scholars put forward the semi-physical simulation as a tool to verify the performance of the controller,but the mature semi-physical simulation platform on the market is expensive,which limits the use of school students.In order to solve this problem,this thesis builds a low-cost semi-physical simulation platform for debugging the control algorithm of the valve-controlled cylinder system.Specific research work is as follows:Firstly,the research status of semi-physical simulation technology is summarized and discussed by referring to domestic and foreign literature.The valve-controlled symmetrical cylinder system is selected as the research example.And the nonlinear state space expression model of the system is derived.The gain of the servo valve is selected and calculated.Then,the essence of studying the semi-physical simulation is to call the numerical solution algorithm to solve and calculate the mathematical model of the system under the exchange and transmission of signals.Therefore,the GNU Scientific Library is introduced to solve the differential equations of the valve-controlled cylinder system.In order to ensure the high real-time performance of the semi-physical simulation,the real-time system of Linux with Preempt-RT kernel patch is selected.The real-time experiment of timer in Linux system with Preempt-RT kernel patch is carried out by logic analyzer.The experimental results show that Linux system with Preempt-RT kernel has good real-time performance.At the same time,the semi-physical simulation platform based on Linux system with Preempt-RT kernel,industrial computer and Advantech USB-4704 data acquisition card is built.The software function of the semi-physical simulation system is designed.The workflow of semi-physical simulation is summarized.The problem of simulation interface analog data acquisition verification and level mismatch is solved.The correctness of the semi-physical simulation platform is verified by simulation.The results show that the error of the data obtained from the semi-physical simulation is small compared with that from the pure mathematical simulation.Finally,due to the insufficient control accuracy of PID control algorithm for displacement trajectory of valve-controlled cylinder system,a backstepping control algorithm based on Lyapunov stability is designed.On the semi-physical simulation platform,the non-interference force and the compound time-varying interference force are used.The displacement tracking test of PID control algorithm and backstepping control algorithm proves that the backstepping control algorithm has better tracking accuracy of displacement trajectory,faster response speed and stronger immunity than PID control algorithm.The feasibility of applying the backstepping control algorithm in the valve-controlled cylinder closed-loop position control system is demonstrated.