Research On Nonlinear Compensation Control Of Bidirectional Synchronous Electro-hydraulic Servo System

As electro-hydraulic servo systems widely applied in the engineering fields of high control accuracy and fast response speed,the nonlinear links of systems themselves and the external interference have become the obstacles that prevent the performances of electro-hydraulic servo systems from further improving.Currently,in addition to the classical linear controllers,most nonlinear controllers remain at the stage of theoretical discussion for a long time,which can rarely be applied to practical systems.This paper is founded by National Natural Science Foundation of China.In this paper,a bidirectional synchronous electro-hydraulic servo system is used as the research object for discussing the effect of typical nonlinear links in the system.Reliable and appropriate nonlinear compensation controllers are designed,and the research work of this paper from three aspects,mathematical modeling,simulation analysis and experimental verification is carried out.The main contents of this paper are given as follows:Firstly,the research status and development trend of electro-hydraulic servo system and its nonlinear compensation control are expounded,and the existing problems in the current electro-hydraulic servo control are analyzed.Based on the electro-hydraulic servo triaxial apparatus,a bidirectional synchronous electro-hydraulic servo system is designed,which lays a solid foundation for the mechanism discussion,model analysis and experimental verification of the nonlinear links.After that,combined with the bidirectional synchronous electro-hydraulic servo system,the mechanism and experimental phenomena of typical nonlinear links such as friction and load are analyzed,and the corresponding mathematical models are built.The uncertain nonlinear link of the coupling of the bidirectional synchronous control system and its impact on the experimental results are discussed.Then,appropriate nonlinear controllers are proposed regarding the nonlinearities of friction,load and coupling mentioned above.MATLAB/Simulink is utilized to investigate the compensation control in the simulation,and the simulation results are compared with the classical PID controller to analyze the errors of output amplitude,phase and coupling.The simulation results indicate that the proposed nonlinear compensation controllers are superior to the classical PID controller in amplitude compensation,phase correction and coupling synchronization.Finally,the bidirectional synchronous electro-hydraulic servo system is utilized to complete the experimental verification.The experimental results show that the proposed nonlinear compensation controllers have effectively compensated the nonlinearities of load and coupling,in which the output error of nonlinear load compensation control is reduced by at least 25%,and the synchronization error of nonlinear coupling compensation control is reduced by at least 20%.