The Pilot Stage Allocation And Control Strategy Research Of Large-Flow Rate Electro-Hydraulic Cartridge Servo-Valve

There are widespread contradictions between "large flow rate" and "high frequency" of large-flow rate electro-hydraulic cartridge servo valve based on traditional series pilot control, i.e. the frequency response ability decrease significantly along with the increase of rated flow rate. Many research results and products from both domestic and aboard have shown that the parallel pilot control strategy has become one of the main methods to solve this problem. But with pilot stage synchronous flow distribution and linear control strategy applied in traditional parallel control strategy, although the response ability of the main stage in a wide range was improved, its frequency response to small amplitude excitation and steady-state tracking accuracy hasn’t seen a substantial increase. In this situation, this paper proposed a newly segmented flow distribution and nonlinear control strategy for100diameter large flow rate electro-hydraulic cartridge servo-valve based on parallel pilot control.In addition, take100diameter active large flow rate electro-hydraulic cartridge servo-vale based on single pilot control as the reaserch object, designed its main stage position closed-loop control algorithm by using Nonlinear Adaptive Robust Control (NARC) and did some preliminary study.In the first chapter of the paper first pointed out that the widespread contradiction between the "large flow rate" and "high-frequency response" of large flow rate electro-hydraulic cartridge servo-valve and its technical difficulties based on the fact that modern large electro-hydraulic equipments are getting higher and higher on the technical requirements for hydraulic servo control systems are larger than ever before. Make a detailed introduction to research and development status both in the domestic and aboard of the large flow electro-hydraulic cartridge servo valve and control strategies for electro-hydraulic servo control systems, and make clear of the main objects and research goals of this paper.In the second chapter, made a detailed analysis of structure and control principles of the parallel pilot stage and main cartridge stage of100diameter large flow rate electro-hydraulic cartridge servo-valve based on parallel pilot control, a newly pilot stage segmented flow distribution and nonlinear control strategy algorithm for pilot stage control was proposed based on traditional pilot stage synchronous flow distribution and linear control strategy. Take a close analysis to the working principle and characteristics of the newly proposed strategy and determine the general principles of control parameters regulation and selection.Make a detailed simulation analysis by using MATLAB/Simulink-AMESim co-simulation platform for three different pilot stage composition, pilot flow allocation and their corresponding control strategies. The studies have shown that the newly proposed pilot flow allocation and control strategy can improve frequency response ability of the main stage in small range and steady-state tracking accuracy without losing the dynamic adjust ability in large range.In the third chapter, take100diameter active large flow rate electro-hydraulic cartridge servo-vale based on single pilot control as the research object, whose mathematical model was established under certain assumptions, and its closed-loop NARC control algorithm for the main stage cartridge valve was constructed and simplified for practical application, complete the virtual prototype simulation analysis of the closed-loop NARC control algorithm for main stage cartridge servo-valve based on S-function model and based on AMESim virtual prototype by using MATLAB/Simulink and AMESim respectively. The simulation results from S-function based model proved the correctness of the closed-loop NARC control algorithm, but the simulation results from AMESim virtual prototype showed that the closed-loop NARC control algorithm failed to reach its theory control performance, and their possible reasons were discussed and analysised.The forth chapter of the paper made a detailed introduction to the MATLAB-xPC real-time control system and the comprehensive test rig. First complete the experimental researches of three different pilot stage flow allocation and control strategies for100diameter large flow rate electro-hydraulic cartridge servo-valve based on parallel pilot control, the experimental results demonstrated that the steady-state tracking accuracy and frequency response to small amplitude signal excitation do improved by using newly proposed segmented flow distribution and nonlinear control strategy. In additional, preliminary experimental researches for closed-loop NARC control algorithm for100diameter active large flow rate electro-hydraulic cartridge servo-vale based on single pilot control was performanced, the experimental results similar to the co-simulaton results based the AMESim virtual prototype, i.e. the closed-loop NARC control algorithm failed to reach its theory control performance.In the last chapter, a summary was made and the deficiencies and problems in the research were pointed out, the focus and direction for further researches were put forward.