Characteristics Prediction Method of Electro-hydraulic Servo Valve Based on Rough Set and Adaptive Neuro-fuzzy Inference System

Synthesis characteristics of the electro-hydraulic servo valve are key factors to determine eligibility of the hydraulic production. Testing all synthesis characteristics of the electro-hydraulic servo valve after assembling leads to high repair rate and reject rate, so accurate prediction for the synthesis characteristics in the industrial production is particular important in decreasing the repair rate and the reject rate of the product. However, the research in forecasting synthesis characteristics of the electro-hydraulic servo valve is rare. In this work, a hybrid prediction method was proposed based on rough set（RS） and adaptive neuro-fuzzy inference system（ANFIS） in order to predict synthesis characteristics of electro-hydraulic servo valve. Since the geometric factors affecting the synthesis characteristics of the electro-hydraulic servo valve are from workers＇ experience, the inputs of the prediction method are uncertain. RS-based attributes reduction was used as the preprocessor, and then the exact geometric factors affecting the synthesis characteristics of the electro-hydraulic servo valve were obtained. On the basis of the exact geometric factors, ANFIS was used to build the final prediction model. A typical electro-hydraulic servo valve production was used to demonstrate the proposed prediction method. The prediction results showed that the proposed prediction method was more applicable than the artificial neural networks（ANN） in predicting the synthesis characteristics of electro-hydraulic servo valve, and the proposed prediction method was a powerful tool to predict synthesis characteristics of the electro-hydraulic servo valve. Moreover, with the use of the advantages of RS and ANFIS, the highly effective forecasting framework in this study can also be applied to other problems involving synthesis characteristics forecasting.

High precise control method for a new type of Piezoelectric electro-hydraulic servo valve

A new type of piezoelectric electro-hydraulic servo valve system was proposed. And then multilayer piezoelectric actuator based on new piezoelectric ceramic material was used as the electricity-machine converter of the proposed piezoelectric electro-hydraulic servo valve. The proposed piezoelectric electro-hydraulic servo valve has ascendant performance compared with conventional ones. But the system is of high nonlinearity and uncertainty, it cannot achieve favorable control performance by conventional control method. To develop an efficient way to control piezoelectric electro-hydraulic servo valve system, a high-precise fuzzy control method with hysteresis nonlinear model in feedforward loop was proposed. The control method is separated into two parts: a feedforward loop with Preisach hysteresis nonlinear model and a feedback loop with high-precise fuzzy control. Experimental results show that the hysteresis loop and the maximum output hysteresis by the PID control method are 4.22% and 2.11 μm, respectively; the hysteresis loop and the maximum output hysteresis by the proposed control method respectively are 0.74% and 0.37 μm, respectively; the maximum tracking error by the PID control method for sine wave reference signal is about 5.02%, the maximum tracking error by the proposed control method for sine wave reference signal is about 0.85%.

Mathematical Model of Steady State Operation in Jet Pipe Electro-Hydraulic Servo Valve

Jet pipe electro-hydraulic servo valve is the heart of feedback control systems,and it is one of the mechatronic components used for precision flow control application.It consists of several precision and ddicate components.The performance of the jet pipe servo valve depends on many parameters.During the developmental stage,it is very difficult to ascertain the function parameters.The steady-state analysis of jet pipe electro-hydraulic servo valve has been made to simulate its fluid characteristics （flowin,flow-out,leakage flow,recovery or load pressure,etc.） by mathematical modeling.Theoretical model was conducted on various affecting parameters on the pressure,the main flow rate of fluid,or leakage flow through the receiver holes.The major parameters studied are jet pipe nozzle diameters,receiver hole diameters,angle between the two centre-lines of receiver hole,nozzle offset,and nozzle stand-of distance.In this paper the research is important to determine and optimize the structural parameters of jet pipe servo valve.Thus,equations of the pressure and flow characteristics are set up and the optimal structural parameters of jet pipe are established.

Analysis on Static Pressure Bearing Seal Characteristics of Guide Sleeve of Electro-hydraulic Servo Cylinder

As a typical bionic walking robot, hydraulic quadruped robot has attracted much attention because of its high mobility, strong load capacity and steady motion. The electro-hydraulic servo cylinder, as its power actuator, requires low friction, good lateral load resistance and high speed motion. The electro-hydraulic servo cylinder hydrostatic bearing seal guide sleeve is taken as the research object in this paper. By using Fluent software to analyze and contrast the film characteristics of rectangular and I-shaped oil chamber of hydrostatic bearing seal guide sleeve, the relationship between piston rod moving speed, eccentricity, oil film carrying capacity, friction force and leakage volume, as well as the relationship between oil feed flow and oil film bearing capacity, friction force, inlet pressure and leakage volume were analyzed. This study provides a theoretical basis for optimizing the static pressure bearing seal parameters.

Study on Oil Cavity Number of Hydrostatic Guide Sleeve of Electro-hydraulic Servo Cylinder

The electro-hydraulic servo drive hydraulic cylinder has many unique advantages, such as fast response, high load stiffness, high control power, strong anti-eccentric load ability and so on, so it has been widely used in industrial control. Based on the guide sleeve of hydrostatic seal of hydraulic cylinder, the reasonable number of oil chamber of guide sleeve is studied in this paper. ICEM CFD software and FLUENT simulation software are used to calculate and analyze the number of different oil chambers of guide sleeve of hydrostatic seal. The temperature field of piston rod with different moving speed, different initial pressure of oil chamber and oil film under different number of oil chambers is analyzed. The relationship between the pressure field and temperature field provides a better basis for optimizing the design of hydrostatic guide sleeve and helps to improve the servo drive cylinder.

Refined modeling and experimental verification of a torque motor for an electro-hydraulic servo valve

The Permanent Magnet Torque Motor(PMTM)is the key electro-mechanical conversion device in an Electro-Hydraulic Servo Valve(EHSV).In this work,a refined model of a PMTM is developed,considering the non-working air-gaps between the upper or lower yoke and the armature,the fringing effect at the limiting holes,and the nonlinear permeability of soft magnetic material.Based on the refined model,the influences of various factors on the calculation accuracy of the magnetic flux at the pole surfaces of the armature and the output torque are investigated.For verifying the validity of the refined model,a Finite Element Analysis(FEA)of the PMTM is conducted,and a test platform is constructed.Compared with existing models,the refined model can better reveal the intrinsic mechanism of the PMTM,and its calculations are more consistent with the FEA results.The experimental results of the armature deflection displacement show that the refined model can accurately describe the output characteristics of the PMTM.

RESEARCH ON THE PERFORMANCE OF NEW TYPE OF PROPORTIONAL PESSURE AND FLOW CONTROL VALVE

A new closed loop flow controlling principle through correcting the valve'sopening area while load pressure is changing is carried out. Further more a principle using only oneproportional valve to compound control pressure and flow is suggested. By using very simpleproportional throttle valve in structure, the functions that five kinds of proportional valves orany two of them combined possess can be complimented. After analyzing, comparing, and testing thedynamic and static characteristics of valve with different controlling principles and main valvestructure styles, the optimized structure styles and control methods are achieved.

Pressure impact characteristic of vane type continuous rotary motor under different buffer structures

In order to solve the problem of pressure shock on the continuous rotary electro-hydraulic servo motor,the mathematical models of pressure gradient under the structure of pre-compressed chamber and U-shaped groove were established.The optimal structure dimensions of the pre-compressed chamber and the U-shaped groove were determined.The fluid models were established by Solidworks under the four structures of triangular groove,triangular groove with pre-compression chamber,U-shaped groove and U-shaped groove with pre-compression chamber.Simulation analysis of depressurization process of fluid models was performed based on FLUENT.The pressure nephograms of different buffer structures were compared and analyzed,and the pressure change curves and pressure gradient change curves in the process of depressurization were obtained.The results show that the optimal edge length of the pre-compressed chamber of continuous rotary electro-hydraulic servo motor is 20 mm in the process of decompression.The pressure reduction effect is the best when the width of the U-shaped groove is 1.5 mm and the depth is 1.65 mm.The U-shaped groove structure with pre-compression chamber is more conducive to alleviate the pressure shock phenomenon of the motor compared with different combine buffer structures.

Static Characteristics of the New Type Nozzle Flapper Amplifier for Double Nozzle Flapper Electro-Hydraulic Servo Valve

A new type nozzle flapper amplifier for double nozzle flapper electro-hydraulic servo valve is proposed in the paper.The electro-mechanical converter of new type nozzle flapper amplifier is designed by using the piezoelectric bimorph and beryllium-bronze materials.The structure and working principle of the new type nozzle flapper amplifier are introduced.Pressure characteristic and flowrate characteristic are analyzed by experimental method.The research results show that pressure characteristic has large amplification factor and output pressure;flowrate characteristic has large linear range and output flowrate.

高压气动压力伺服系统的鲁棒控制

高压气动压力伺服系统的参数不确定性和未建模动态制约了其控制精度的提高,针对此提出了基于RISE的自适应鲁棒控制算法用于高压气动压力伺服系统的控制。考虑到核心元件高压电气伺服阀的控制性能对高压气动压力伺服系统高精度控制的影响,设计了交叉对比实验,实验结果表明,伺服阀位置控制算法有助于避免正弦信号失真、减小稳态压力抖动,系统压力控制算法能提高系统的响应速度和动态跟踪能力。

电液伺服阀压力增益影响因素灵敏度分析

压力增益是电液伺服阀核心性能指标之一,但电液伺服阀存在机电液强耦合性、封闭性和结构参数复杂性,限制了电液伺服阀压力增益的提升,亟需明确压力增益的影响因素及权重大小。故以偏转板射流伺服阀为研究对象,建立伺服阀机、电、液多环节数学模型,得到电液伺服阀整阀的状态空间模型,然后,结合压力增益公式,采用一阶灵敏度分析方法,分析伺服阀结构参数对伺服阀压力增益影响相关性和权重,最后,基于电液伺服阀性能测试实验平台,验证了前置级喷嘴尺寸以及滑阀级遮盖量两个典型结构参数对压力增益的影响。研究成果为电液伺服阀静态性能的提升提供了一定的理论指导。

非对称喷嘴挡板压力伺服阀建模与特性研究

针对一种具有非对称喷嘴挡板结构的压力伺服阀(简称非对称压力阀),建立其数学模型及MATLAB/Simulink仿真模型,分析了整阀的静动态性能,并研究了非对称结构的设计原则。结果表明:该阀为带死区的单向正增益压力伺服阀,其输出压力高、线性度好、动态响应快;喷嘴腔压力和输出压力交叉点与静态性能指标具有唯一的映射关系,可利用交叉点位置来判断伺服阀性能是否达到工作要求;阀芯端面面积非对称是前置级非对称的来源,为了保证非对称压力阀的零位稳定性和性能要求,需将前置级设为非对称形式,其固定节流孔液阻系数比大于喷嘴孔液阻系数比,而喷挡间隙的非对称有利于减小喷嘴结构参数的影响,便于伺服阀的尺寸设计和调试;最后通过实验验证了数学模型的准确性。建立的数学模型及仿真模型可为压力伺服阀的结构设计及优化提供依据。

国产电液伺服阀在可控震源上的测试分析

电液伺服阀是可控震源电液转换的核心液压元器件,对可控震源输出力信号有着直接的影响,但可控震源工作环境恶劣,宽频,瞬时大流量以及高压高温、高可靠性等工作特点对电液伺服阀提出了严苛的要求,该设备一直以来依赖进口,近年来某型号国产电液伺服阀开始在可控震源上进行应用试验,经过测试、改造,性能不断提升,本文总结分析了该产品在可控震源上进行的一些测试数据,希望能够为将来的实际应用提供一些技术上的参考。

射流偏转板伺服阀偏转板正交仿真试验优化设计

以一种射流偏转板伺服阀前置级偏转板为研究对象,利用前处理软件建立真实的流体域模型,通过流场仿真及正交试验研究了偏转板直径、偏转板厚度、导流口高度、导流口夹角和导流口出口宽度5个结构参数对射流偏转板伺服阀前置级压力特性的影响。结果表明:各因素影响权重由大到小依次为偏转板厚度、导流口出口宽度、导流口夹角、导流口高度、偏转板直径。相较于原结构,正交试验得到的优化结构在偏转板偏移0.01 mm时,接收孔压差增大5.65%,以上研究可为射流偏转板伺服阀前置级结构的优化提供参考。

机液反馈式偏转射流压力伺服阀机理及特性分析

电液压力伺服阀是飞机刹车压力伺服系统的重要控制元件。为满足压力伺服阀高动态和高可靠性的要求,设计了一种机液反馈式偏转射流压力伺服阀。为研究该压力伺服阀的工作机理和静动态特性,建立了其数学模型和Simulink仿真模型。通过仿真结果可知,压力伺服阀的死区电流为1 mA,最大输出压力为10 MPa,压力增益为1.15 MPa/mA,幅频宽为26 Hz,相频宽为36 Hz,动静态性能良好,满足系统要求。通过实验对理论、仿真模型的准确性进行了验证,验证结果表明,理论模型能较好地预测压力伺服阀的静态性能,为压力伺服阀的结构设计和优化提供理论支撑和仿真参考。

高温下射流管伺服阀流量特性分析

为分析射流管伺服阀的前置级能量转换特性,基于动量守恒和能量守恒定理,建立射流管伺服阀前置级数学模型,并对高温下射流管伺服阀流量特性与前置级结构参数之间的关系进行分析;分别对2种不同型号的射流管伺服阀进行试验研究,得到常温下射流放大器的恢复压力特性以及2种型号伺服阀在30℃和150℃下的小信号空载流量特性。研究结果表明:高温下油液黏度降低导致射流速度增大,恢复压力增加,空载流量变大;前置级结构参数会影响高温下射流碰撞面积的变化幅度,进而影响恢复压力和空载流量。当射流孔与接收孔直径之比在0.69附近时,高温下射流碰撞面积的变化幅度最大,碰撞损失的动量增加,此时空载流量的变化最小。在相同温差下,若空载流量的变化幅度未达到最大,则射流喷嘴的自由射流距离会影响射流碰撞面积的变化,进而影响空载流量的变化。2种伺服阀在120℃温差下空载流量的变化幅度分别为4%和16%,试验结果与理论计算结果一致,验证了所建立的前置级数学模型的正确性和有效性。

非对称伺服阀在阀控缸电液伺服系统中的应用

电液伺服系统广泛应用于机械设备中,伺服阀是电液伺服系统中的关键元件,非对称伺服阀的出现为阀控非对称伺服油缸电液伺服系统的设计提供了新的选择。采用孔口流量方程和流量连续方程分析了伺服阀非对称结构和对称结构分别控制非对称伺服油缸时伺服油缸两腔的压降情况,得到了2种设计结构非对称伺服油缸两腔的压降指标。结果表明,在合理选择伺服阀阀芯结构和伺服油缸结构匹配时,可以有效减少伺服油缸两腔的压降,减少功率损失。对三轮旋压机横向进给电液伺服系统进行分析,优化了系统压力和电机功率,通过压力传感器检测非对称伺服油缸两腔的压力验证了理论分析的准确性,为电液伺服系统伺服阀阀芯结构和伺服油缸结构的合理匹配设计提供了理论支持。

刹车控制器刹车压力输出异常故障分析

主要就飞机的刹车控制器的刹车压力异常输出的故障进行分析定位,将问题定位至刹车电流输出异常;进一步通过分析刹车电流输出电路工作原理,得出具体故障原因;对伺服阀驱动电路进行改进,通过试验、仿真等验证,改进后的电路可有效解决故障问题。

进气压力调节执行机构故障诊断方法研究

面向高空台进气压力调节系统试验和维护需求,提出了一种基于滑模观测器的执行机构故障诊断方法。考虑特种调节阀的流量-压差气动特性对执行机构外负载作用机制,建立了电液伺服执行机构的非线性模型。由其识别出最佳估计数学模型,以获得自适应滑模观测器。分析确定不同故障对应伺服阀或液压缸的主导特征参数,据此选择可观测状态量且结合自适应阈值进行判断某部件是否发生故障,仿真验证该观测器对典型故障的诊断效果。结果表明,基于自适应滑模观测器的故障诊断方法可实现对进气压力调节系统中电液伺服执行机构典型液压、机械、电气故障的诊断和定位,诊断准确率达91%以上。

高升率液压脉冲系统机制分析与设计

为模拟航空作动器高压力、高升率工作环境进行脉冲试验,设计了T形波脉冲系统,系统采用压力传感器和电液伺服阀构成闭环控制,通过控制经伺服比例阀流入非对称增压缸低压腔的流量建压。在建立蓄能器、电液伺服阀及增压缸-被试工装件的压力-流量数学模型的基础上,基于AMESim搭建仿真模型,对比分析不同工装件容积、脉冲升率对系统动态性能的影响。仿真结果表明,系统主要由蓄能器提供瞬时流量快速建压,释放能量后,液压泵需要在一个周期内为蓄能器补充0.25 L液压油;为保证压力升率,系统最低流通能力为250 L/min。依据仿真结果选择系统关键元器件搭建脉冲试验台,试验台实现峰值压力42 MPa、升率1100 MPa/s的T形波,并稳定持续20万次脉冲,验证了仿真分析的正确性。