Research On Nonlinear Control Method Of Hydraulic System

Forging hydraulic press is considered as one of the developing directions offorging press because of its fast forging speed,high control accuracy,highautomation,wide technology range,saving energy and material. It is a product toreplace large type of forging hammer and mesotype and minitype common forgingwater press.In the thesis,the current status and development tendency of hydraulic forgingpress domestic and abroad are investigated. The work principle of hydraulic press andits control system are studied. Based on the analysis of isothermal hydraulic forgingpress, the mathematical model of the hydraulic system is established.Through differential geometric feedback linearization, the affine non-linear modelof the hydraulic system is equivalent to a linear model. As a result, the system can beanalyzed and designed with linear system theory. The relation of uncertaintycomponent of the system model before and after the exact feedback linearizationmapping is discussed.The principle and method of robust controller design based on LMI method isintroduced. Considering the the impact of the external disturbance, according to therequirements of the simultaneous performance of the hydraulic system, the controllerbased on H∞robust control method is designed. The simulation results show a gooddynamic performance. And the results are compared with the PID control algorithm,and it is showed that the system has a pretty good anti-jamming performance.Considering the uncertainty of the model, the controller which can resist both theuncertainty of the model and the external disturbance is designed based on H∞robustcontrol method.