P-Q伺服阀及力控制系统的键图建模

本文介绍了P-Q伺服阀的结构和工作原理,在着重分析了伺服阀各部分的流量方程和力(矩)平衡方程基础上,运用键图对伺服阀进行建模。采用P-Q伺服阀控制的电液力控制系统具有很多优点,建立其系统键图模型,并通过仿真分析和试验对比,验证了P-Q伺服阀及电液力控制系统的键图模型是正确的。     

基于阀控非对称伺服缸的半主动升沉补偿研究

深海有缆水下机器人在恶劣海况下作业时,常配备相应的升沉补偿系统以提高水下机器人释放和回收作业的安全性。重点研究了基于阀控非对称伺服缸的半主动升沉补偿方式,介绍了与实际系统相似的半主动升沉补偿模型系统,并阐述了系统的功能组成和工作原理。考虑了弹性负载的影响,建立了由伺服放大器、阀控非对称缸和弹簧负载模型等构成的电液位置伺服系统的传递函数模型。在此基础上,根据阀控非对称缸的输入电压与活塞输出速度之间的非线性关系,设计了分段前馈控制器,以提高系统的动态响应性能。最后进行了半主动升沉补偿性能试验,结果证明了所研究的半主动升沉补偿方式的有效性。     

基于特性曲线的电液伺服阀神经网络故障模式识别

对电液伺服阀故障进行准确快速诊断十分重要。以喷嘴挡板式电液伺服阀为研究对象 ,分析伺服阀特性曲线与故障的关系 ,提出基于特性曲线的伺服阀故障诊断方法。通过实验提取一些常见故障模式的特性曲线 ,运用 BP神经网络 ,实现了电液伺服阀的故障诊断和模式识别。运用的神经网络结构简单 ,训练次数少 ,识别准确率较高 ,是一种实用可行的电液伺服阀故障诊断方法     

波登管2D压力伺服阀反馈装置的特性研究

设计了2D压力伺服阀样机模型,利用波登管作为伺服压力反馈单元保持其输出压力恒定。针对波登管在特定范围内随压力线性变形的特性,在分析其变形机理的基础上,建立了数学模型,仿真分析了其受力变形过程,得到其结构参数对线性变形的影响。设计了波登管线性变形实验方案并搭建实验平台,实验结果表明：随着压力的升高,波登管的变形与压力升高基本成线性关系,16MPa时,其线性变形量为0.7mm; 动态实验中波登管从受冲击开始到基本稳态耗时约0.9ms。实验结果与仿真分析基本一致,波登管的特性研究为其在2D压力伺服阀上的应用奠定了基础。     

基于虚拟仪器的电液伺服阀的静态测试应用

虚拟仪器是仪器仪表发展的一个新阶段。较全面地论述了虚拟仪器的概念、特点,介绍了基于虚拟仪器技术的电液伺服阀的静态测试系统。该系统可以快速准确地检测和诊断液压系统的故障。     

基于MATLAB的阀控缸伺服系统仿真分析

根据液压伺服系统的基本理论,推导了阈控缸液压伺服系统的传递函数模型;用MATLAB软件对系统的动态特性进行仿真分析,并进行了参数修正;结果表明所建数学模型及仿真结果接近实际工况,并且经参数修正后的控制系统是稳定的.     

伺服阀流量单边输出故障分析

M00G30系列伺服阀是一种小流量的伺服阀，在国产化研制过程中曾经出现过流量单边输出故障。该文从伺服阀的工作原理入手，通过对该故障进行理论分析，并经实际验证，找出了产生故障的根源，提出了改进措施。     

磁流体对伺服阀力矩马达动态特性的影响

利用磁流体在外加磁场作用下具有较高饱和磁化强度和较大粘度的特点,提出了采用磁流体改善伺服阀力矩马达动态特性的方法。通过把磁流体添加到伺服阀力矩马达的工作气隙,来增加力矩马达的阻尼,改变力矩马达的动态响应特性,提高力矩马达及伺服阀的稳定性,从而有助于抑制和消除伺服阀自激振荡及噪声。通过对磁流体作用机理及力矩马达磁回路的分析,给出了磁流体作用力数学模型,以及添加磁流体和不添加磁流体的力矩马达动态数学模型,采用MATLAB/Simulink对添加磁流体和不添加磁流体的伺服阀力矩马达动态响应特性进行了分析,给出了分析结果,并通过激光位移传感器对伺服阀力矩马达动态响应特性进行了试验研究。仿真及试验结果表明,磁流体可增加伺服阀力矩马达的阻尼比,从而提高伺服阀力矩马达的稳定性和抗干扰能力。     

一种变量泵斜盘电液伺服控制系统研究

针对航空动力系统变量柱塞泵斜盘角度控制,设计并实施了一种简化结构的节流式电液伺服控制系统。通过数字仿真简化系统模型,并为斜盘位置控制设计控制算法,在X型航空发动机特性半物理仿真试验系统上完成了功能试验。结果表明,结构简化的变量泵斜盘位置电液伺服控制系统工作有效、快速、稳定。     

双喷嘴挡板伺服阀前置放大器的流场分析

运用FLUENT软件对伺服阀双喷嘴挡板级进行了三维流场分析,获得了不同喷嘴挡板距的控制压力和恢复流量,运用二次函数拟合得到控制压力与恢复流量的数学模型,并分析了喷嘴挡板内部流道对伺服阀性能的影响。     

酒钢炉卷轧机液压APC系统建模与仿真研究

以酒钢炉卷轧机为对象，在分析了轧机液压AGC系统及其运行机理的基础上，以伺服阀的基本方程、液压缸连续性方程、液压缸和负载的力平衡方程为基础，建立了酒钢炉卷轧机位置控制（APC）系统的数学模型，并利用Matlab／Simulink系统仿真，通过试凑法对PID控制参数进行了整定和调节，对进一步研究炉卷轧机具有一定的实用价值。     

Nonlinear control of a multicomponent distillation process coupled with a binary distillation model as an EKF predictor

The work is devoted to design the globally linearizing control (GLC) strategy for a multicomponent distillation process. The control system is comprised with a nonlinear transformer, a nonlinear closed-loop state estimator [extended Kalman filter (EKF)], and a linear external controller [conventional proportional integral (PI) controller]. The model of a binary distillation column has been used as a state predictor to avoid huge design complexity of the EKF estimator. The binary components are the light key and the heavy key of the multicomponent system. The proposed GLC-EKF (GLC in conjunction with EKF) control algorithm has been compared with the GLC-ROOLE [GLC coupled with reduced-order open-loop estimator (ROOLE)] and the dual-loop PI controller based on set point tracking and disturbance rejection performance. Despite huge process/predictor mismatch, the superiority of the GLC-EKF has been inspected over the GLC-ROOLE control structure.     

电液伺服系统动力机构最佳参数的选择方法——介绍P-Q计算尺

本文介绍一种专用计算尺（P-Q尺）,用来选取电液伺服系统动力机构的最佳参数。利用该尺,可按下列四种最佳指标之一确定伺服阀空载流量Q M和油缸活塞有效面积A（或液压马达的容积排量D）。1.所需功率最小;2.A（或D）最小（系统快速性好）;3.Q M与A相对小（准最佳）;4.已有伺服阀,判别其可用性并选取此条件下的A最小值。该计算法的特点是允许负载轨迹为任意几何形状,油缸两腔的活塞面积可以相等或不等。而过去的方法只适用于直线、椭圆等特殊的负载轨迹,而且油缸两腔的活塞面积必须相等[1]～[5]。     

双喷嘴-挡板电液伺服阀抗污染能力研究

简要介绍了喷嘴挡板伺服阀的结构组成和工作原理。针对双喷嘴挡板电液伺服阀在工作过程中抗污染能力偏低的特点,对其常见的失效机理进行分析,通过对大量故障伺服阀进行拆解和故障分析,并与抗污染能力较好的同类产品相对比,得到了喷嘴挡板伺服阀产生卡堵故障的主要原因。在上述分析的基础上,从结构设计、外部和内部多余物控制等方面进行优化设计和改进,并通过相关实验验证,得出有效提高喷嘴挡板阀抗污能力的具体对策,在试生产和装调测试过程中取得了良好收效。     

A New Circuit for Current Reversal Chronopotentiometry

Electrochemical techniques are being used today to measure the kinetics of homogeneous chemical reactions [1, 2]. The value of one of the techniques, current reversal chronopotentiometry (CRC), has been demonstrated with the study of several chemical systems [3, 4]. Recently, a circuit designed for cyclic chronopotentiometry (CC) utilizing tube-type operational amplifiers was published [5]. This circuit of course is also suitable for CRC and in fact has been used to elucidate the mechanism of the loss of water from p-hydroxyaminophenol [6]. The main disadvantage of this circuit is that the experiment is initiated by unshorting the electrochemical cell. Undesirable galvanic reactions are possible at the working electrode when it is shorted to the unpoised auxiliary electrode [7]. This has been circumvented by making the auxiliary electrode a large area reference electrode.

However, this can be inconvenient and, moreover, is disastrous if appreciable reactions can proceed at zero volts vs. the particular reference electrode used.     

某型飞机电液压力伺服阀试验台设计

基于某型飞机电液压力伺服阀的测试需求进行了试验台的设计.试验台由进行液压能控制与调节的液压试验台和进行试验控制的控制柜组成.可以进行压力伺服阀性能参数测量,满足了航修厂对压力伺服阀的测试要求,在应用中取得了良好效果.     

电液驱动Stewart平台模型参数辨识方法

电液驱动Stewart平台是一个多输入多输出复杂并联机构,各通道间存在严重负载交联耦合。在确定平台各通道性能参数时,按照简单的阀控缸系统进行理论计算或系统辨识,结果和实际情况相差极大,这严重影响平台控制系统的设计和系统性能的提高。为了解决上述问题,设计一种基于Levenberg-Marquardt寻优算法的六维互不相关信号激励的Stewart平台闭环辨识算法,并应用于电液驱动Stewart平台试验样机。试验结果表明该辨识算法准确地辨识出平台通道性能参数,取得较满意的辨识结果。     

Exact solution of one problem of magnetostatics in bipolar coordinates (continued)

An exact solution for a linear problem of magnetostatics about an infinite cylinder with an infinite noncoaxial cylindrical flaw has been derived in the system of plane bipolar coordinates under the condition that external magnetizing field remains unchanged along the length axis of this model body. The solution has been tested for theoretical veracity and compared with the solution of a similar problem that was obtained by one semianalytic method [2]. For a particular problem about a halfspace with an infinite cylindrical flaw, an exact solution has been obtained and compared with results that were achieved by other methods. The mismatch between the solution of the problem about a halfspace and the solution of the problem with passage to the limit of a half-space has been considered. An algorithm is described for solving the inverse problem of separate determination of flaw depth and dimensions.     

Cost estimation system of dies manufacturing based on the complex machining features

Part manufacturing estimation cost is a critical and important task for industrial firms. Price evaluation helps the enterprise occupy a successful competitiveness in the market. In fact there are three main approaches for the manufacturing cost evaluation the analytic approach, the analogic approach and the parametric approach. This paper presents a cost estimation system of manufacturing dies based on a semi-analytic approach. The developed system uses a semi-analytic approach based on the principle of the analogic approach and analytic approach. This principle has recourse to the analogic approach to search for analogies between the shapes to be machined before grouping them into complex machining features [1]. For each feature parameter the system generates a process to be used as a sample and consequently a model of machining time. In a second stage and by using the analytic approach, the cutting time is determined either by removal rates of metal units for rough operation (cm³/min) or from the finishing operation surface (cm²/min) or by both production ways [1]. The after cutting return time is calculated through the equations developed for each machining type [2].     

Artificial evolutionary approaches to produce smoother surface in magnetic abrasive finishing of hardened AISI 52100 steel

In this work, two models of feed forward back-propagation neural network (FFBP-NN) and adaptive neuro-fuzzy inference system (ANFIS) have been developed to predict the performance of magnetic abrasive finishing process, based on experimental data of literature [7]. Input parameters of process are electromagnet’s voltage, mesh number of abrasive particles, poles rotational speed and weight percent of abrasive particles, and also the output is percentage of surface roughness variation. In order to select the best model, a comparison between developed models has been done based on their mean absolute error (MAE) and root mean square error (RMSE). Moreover, optimization methods based on simulated annealing (SA) and particle swarm optimization (PSO) algorithms were used to maximize the percent of surface roughness variation and select the optimal process parameters. Results indicated that the models based on artificial intelligence predict much more precise values with respect to predictive regression model developed in main literature [7]. Also, the ANFIS model had a lowest value of MAE and RMSE with respect to others. So it was used as an objective function to maximize the surface roughness variation by using SA and PSO. Comparison between the obtained optimal solutions and analysis of results in main literature indicated that SA and PSO could find the optimal answers logically and precisely.