面向液压系统原理图自动建模的动态仿真软件研究.pdf

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1、面向液压系统原理图自动建模的动态仿真软件研究华中理工大学 张 勇 吴先福 王 勇 李从心 黄树槐摘要:本文介绍了一种面向液压原理图建模的通用液压系统动态特性仿真软件,该软件可以自动识别液压原理图,自动建立数学模型并进行仿真运算,对复杂系统的设计,优化和调试具有重要的实际意义。关键词:自动识别 液压原理图 自动建模 仿真1 简介许多大型设备的液压系统通常包括多台泵、多个阀组、多个执行元件和较长的管道,具有压力高、液压冲击严重等特点,系统复杂。为提高复杂液压系统设计水平、在设计阶段发现液压系统动静态特性方面存在的问题、了解多负载系统之间的相互影响和液压系统中的压力冲击、进行系统结构和参数优化、寻求

2、最佳控制模型和参数、缩短系统的安装和调试时间和节省中间试验费用,迫切需要开发一种通用的液压系统动态仿真软件。目前国内还没有面向液压原理图,人机交互过程中贯彻可视化思想的液压系统动态仿真软件,结合我校承担的“8MN快锻液压机”以及“613MN粉末压制液压机”课题,本课题组开发了一种面向液压原理图的动态仿真软件。液压系统的动态仿真虽然受到了广泛的重视,但是编制一个可供使用的仿真程序涉及到多方面的知识,为了使那些不熟悉建立数学模型和计算方法,以及不熟悉编程知识的液压专业技术人员能方便地使用该仿真软件,采取了以下的技术路线:以Auto2CAD1210(1310)for Windows为支撑环境建立参数

3、化液压元件图形库,用Visual C+在ADS(Auto2CAD Development System)实现绘制液压原理图和建模一体化,利用FoxPro215for Windows数据库建立液压元件参数和模型算法数据库,采用SQL(Struc2tured Query Language),DDE(Dynamic DateEx2change)和ODBC(Open Data Base Connect)实现基于液压原理图的自动建模与仿真,从模型结构,建模方法和仿真算法三方面统一解决复杂液压系统仿真模型中的病态问题,结合人工智能方法,实现液压系统原理图智能布图及快速布线。为了获取建立数学模型所需要的重要

4、信息,自动建立液压系统的动态数学模型,本课题组在德国亚琛工业大学的DSH(Digtal Simulation of Hydraulic System)、图1英国巴斯大学的HASP(Hydraulic System AutomaticSimulation Program)、日本油空压学会的BGSP(BondGraphs Simulation Program)等液压系统仿真软件的基础上,结合计算机领域和液压领域的最新发展以及人工智能等学科的有关技术,以Windows,AutoCADfor Windows,Foxpro215for Windows等软件为开发平台,开发了复杂液压系统通用仿真软件。该软

5、件可用于对机、电、液、计算机混合控制的系统进行仿真,采用面向图形操作的方法,贯彻了可视化思想,用户操作方便,具有一定的智能化水平。程序流程图如图1所示。2 液压系统动态数学模型的自动建立在进行仿真运算时,液压系统通常可以描述成普通的微分方程组,并采用数值积分求解,其微分方程可以表示成矢量形式:y(t)=?f(y(t)就以图2所示的液压系统为例,来说明数学模型的建立过程。图2对于特定的容腔,其压力方程可写为:p1=VQidt+p0其中某个元件的运动方程为:?x=1mFidt+?x0对于旋转构件则为:=1I Mdt+0其中为工作介质的弹性模量。为了能自动生成液压系统的动态数学模型,首先必须得到下列

6、信息:(1)液压元件的基本参数,主要指有关动态特性的参数。(2)液压系统各元件之间及容腔之间的连接关系,这些联系可概括为液压节点、机械节点、电气节点及外部构件的连接,其中液压节点可以表示为与该节点相连的构件的集合,液压节点就是所谓的容腔。对于每个容腔就可以建立一个压力方程。111998年第1期(3)对整个液压系统实施的控制方式,控制算法等。(4)液压系统的动作真值表。液压系统主要包括五个组成部分:液压泵站、执行元件(液压缸或马达)、控制阀组、辅助装置(管道和油箱等)和电控部分。液压系统原理图绘制的最大的特点是整个图形采用特定的图形符号按照所需实现的功能绘制,这些图形符号都已经标准化。因此根据国

7、标GB和国际标准(ISO12191976)的规定,以AutoCAD绘图软件为基础,建立了一个比较完善的液压元件图形库符号库,并采用图形屏幕菜单技术加以显示。用户只需使用鼠标选取菜单即可任意调用。所有元件的图形符号都是以AutoCAD块的形式分类存储的,由于Auto2CAD本身具有较强的块操作能力,使用该符号库可以方便地绘制各种符合国标的复杂液压系统原理图。在图形符号库的支持下,同时使用修改后的连线函数,可以很方便地连接各元件的端口。液压原理图的自动 识 别,是 通 过 读 取DXF(Drawing Exchange File)文件来实现的。DXF文件是AutoCAD标准图形交换文件,也是CAD

8、领域事实上的工业标准交换文件,几乎所有的CAD软件包都支持它。DXF文件由一系列具有专用格式的ASC码组成,通常分为Header(标题节)、Tables(表节)、Block(块节)、Entites(实体节)和一个文件结束组,且都用文件分隔符(即0组)来确定各自的界限。DXF文件包含的信息量极大,并且人工检查一个DXF文件十分困难,但DXF文件的格式能够容易地用程序进行处理。其文件格式的设计是深思熟虑的,程序能够通过“过滤”只读取所需要的信息,跳过无关信息。在本软件中,对液压系统原理图生成的DXF文件,只需提取ENTITES(液压元件块)中和命令LINE(画直线)中有关信息即可。系统的有关信息都

9、被记录到外部数据库中,以寻找元件连接关系。图3为液压原理图自动识别程序流程图。图3 原理图识别程序流程图运用人工智能技术中的宽度优先搜索的方法来寻找元件间的连接关系,宽度优先搜索方法是按图4所示的顺序来进行全局搜索,即是由扩展结点S0(所谓结点即相当于液压系统原理图中的元件和直线端点)产生结点1,2,然后扩展节点1,生结点3,4,然后扩展2,生成5,6,7,如此一层一层扩展下去,直到搜索完毕为止。宽度优先搜索算法如下:(1)open表 存放待扩展的结点,即端结点,它是一个先进先出的队列;(2)closed表 存放已被扩展过的结点;(3)把待扩展的结点送open表;(4)如果open表空,则搜索

10、结束,否则继续;(5)若open表中包含目标结点,则找到解,解可从目标结点开始直到初始结点的返回指针中得到;(6)取open表中第一个结点(记为S0),并送closed;(7)若S0无后继结点,则转(4),否则继续;(8)将S0的所有后继结点送open表的末端,并置这些结点的父结点指针为指向S0的指针,并转(4)。图4 宽度优先搜索法示意图在算法中,新产生的结点状态与某个已产生的结点状态,本软件将其忽略。另外,在扩展过程中,软件要防止任何一结点有两个以上父结点。在本软件中,首先对第一个端口作标号N(此时N=1),通过宽度优先搜索找出该端口相关联的所有直线,并将这些直线作标号N,然后找出所有与N

11、号直线相连的端口并作相同标号N,依此类推,对其它端口采用同样寻找方法,所有标号相同为N值的端口即为相连端口形成一个液压容腔,从而找出液压系统所有元件的连接关系。至此,我们可以找到液压系统各元件之间的内在联系,再加上从数据库中提取液压系统及元件的基本参数,便可以生成液压系统的动态数学模型(即一个联立的微分方程组),利用Runge-kutta、Hamming等数值计算方法就可以进行仿真运算。3 一个仿真计算实例为验证本动态仿真软件的的效果,对图5所示的液压系统进行了仿真。图5该系统为一个位移闭环控制系统。其中采用了低成本的KDG4V3 2020N Z MUH720型比例控制阀和配套的EEAPAM5

12、23F30型比例放大模板;LS703型增量式光电编码位移传感器和配套的EXE602D/1F型整形放大器;非对称油缸两腔面积分别为1962mm2和1347mm2。采用带有多功能智能接口模板的386/SX计算机。21机床与液压图61号容腔压力变化曲线 图72号容腔压力变化曲线图83号容腔压力变化曲线 图94号容腔压力变化曲线图10 液压缸活塞速度变化曲线 图11 液压缸活塞位移变化曲线油源压力:5106Pa;流量40L/min;溢流阀溢流压力5106Pa;溢流流量40100L/min;活塞及质量块质量为500kg;采样时间:010001s;仿真步长:010001s;仿真起始时间:010s;仿真终止

13、时间:015s.图6图11曲线依次为在闭环控制状态下1、2、3、4容腔的压力随时间变化曲线以及液压缸活塞的速度、位移随时间变化曲线。此时液压缸上所受的外负载为5000N,设定控制位移为10mm,从图中可以看出,最后液压缸活塞在10mm处稳定下来,与实际情况相符。4 小结(1)采用面向液压原理图自动建模方法开发出的动态仿真软件,能极大地方便用户,而且比较清晰直观。(2)在自动建模中引进了广义“容腔”的概念,机械节点和电气节点可以当作广义的“容腔”来处理。这些“容腔”在本质上具有同一特点,即在系统各个元件的数学模型中具有相同性质的状态变量(如压力、位移、速度、电压、电流)通过“容腔”的联系而建立整

14、个液压系统的状态方程,从而解决目前仿真软件中不能很好处理闭环控制系统的问题。(3)液压系统的动态仿真可以提高系统的设计水平,在设计阶段预见系统中存在的缺陷,从而在设计阶段消除它,同时系统仿真也对液压系统结构参数的优化以及现场调试具有重要的实际意义。参考文献1 李从心,Virvalo Tapio,赵铁男 1 非对称油缸控制系统仿真及控制 1 中国机械工程,1993年第4卷第3期2W1 霍夫曼著,陈鹰译1 液压元件及系统的动态仿真1 杭州:浙江大学出版社,19883 钟廷修 1 液压CAD技术第四讲液压系统的动态仿真 1 液压与气动,1988年第2期(来稿时间:1997年1月2日)(上接第40页)

15、4 结论本文根据高频响蓄能器的设计准则,开发出一种新型高频响串联蓄能器,且结构简单,易于加工制造。理论及试验结果表明,与常规并联蓄能器比较,串联蓄能器对位于它前面或后面的不同频率的压力脉动均有良好的吸收效果,而且衰减频带宽。参考文献1 苏尔皇.管道动态分析及液流数值计算方法.哈尔滨工业大学出版社,1985.42 小英一等.油压?起因 油压?内 压力脉动 生 亻云.日本机械学会论文集(B编)61卷583号.1995.33 赵克定等.并联和串联囊式蓄能器的试验研究.机床与液压,1991(3)4 史维祥,曹秉刚.流体滤波消声器.机床与液压,1986.(5)5 日本液压气动协会编.液压气动手册.机械工

16、业出版社,1984.11(来稿时间:1996年11月8日)亚微米超精密数控车床问世哈尔滨工业大学精密工程中心研制成功一种具有国际先进水平的超精车床,并已通过了专家鉴定。它是目前国内自行研制的精密度最高、功能最齐全的超精数控车床。其主要技术性能指标达到或超过国际先进水平。该车床的床身、导轨和主轴均采用石材,主轴和导轨为气浮。整机安放在空气弹簧上,无齿轮皮带传动。它可加工外圆柱、端面、内孔以及复杂的曲面。用它加工出的镜而,精度接近微米的程度。胡正隆 311998年第1期MACHINE TOOL&HYDRAULICSNo11,1998(Total lssue No1151)Abstracts and

17、 Keywords in EnglishDesign of computer monitoring in multivariable electrohydraulic systemSheng Wanxing et al(3)Abstract:In accordance with working characteristics of such multivariable electrohy2draulic system for refining equipments,this paper analyzes design principle and method ofcarrying out co

18、mputer monitoring in the system,and givesout software and hardware struc2tures.Keywords:Electrohydraulic system Microcomputer monitoring Software configurationMan-machine interfaceDesign of fuzzy controller applied in hydraulic loading system with secondary regulationTian Lianfang et al(5)Abstract:I

19、n the paper,the fuzzy control is introduced into hydraulic loading systemwith secondary regulation,this kind of controller applies the strategy of weighted coefficientselfoptimizing and PI control on the basis of traditional fuzzy controller which overcomes theshortcomings of slow response and low s

20、tatic accuracy of existed controller.Simulationsachieve good results.Keywords:Secondary regulation system Loading Fuzzy control PI controlApplication of adaptive control to electrohydraulic simulation system for well pumpingunitFeng Y ongjian et al(7)Abstract:This paper introduces a new electrohydra

21、ulic simulation system,with havingsuch characteristics as large flow rate(8.7510m/s)and long stroke(3.5m).It de2scribes,in detail,the basic constitution and the working principle of the system,and carriesout simulation test.The tested results show that the simulation system has excellent repro2ducib

22、ility to the motion law of the well pumping unit,with high simulation accuracy and sta2ble and reliable work.Keywords:Well pumping unit Hydraulic servo Adaptive controlRobust variable structure control of oil temperature in hydraulic systemSha Daohang et al(9)Abstract:In this paper,an approch of dis

23、crete robust variable structure control(RVSC)is proposed and applied to an oil temperature control of hysraulic systems.Simula2tion results show that the proposed RVSC may achieve smaller time response,systemsovershoot and external disturbance than the conventional PID.Keywords:Temperature control R

24、obust control Variable structure controlResearch on simulation software of auto-modelling based on hydraulic principle dia2gramZhang Y ong et al(11)Abstract:This paper introduces a general simulation software of dynamic characteris2tics in hydraulic system by modelling mased on hydraulic principle d

25、iagram.The softwarecan automatically identify hydraulic principle diagram,establish mathematical models andcarry out simulation operations,with having an important and actual meaningfor designing,optimizing and debugging a complicated system.Keywords:Auto-identification Hydraulic principle diagram A

26、uto-modelling Simula2tionThe theoretical analysis of the disturbance torque in electrohydraulic simulator and thestudy of methods to overcome itSu Donghai et al(14)Abstract:Considering the special problem of disturbance torque existing in the loadingsystem of electrohydraulic load simulator,this pap

27、er analyzes the cause of the disturbancetorque occurring and indicates the relations of disturbance torque to the static and dynamicperformances of the control system.Based on theoretical analysis,the effective methods toovercome the disturbance torque are put forward.Keywords:Electrohydraulic load

28、simulator Disturbance torqueDesign code on imformation about CAD/CAM for hydraulic manifold blockHe Jigang et al(16)Abstract:This paper gave a comprehensive analysis of the requisite information aboutthe produce in the processof computer aided design,computer graphic display and processingof numeric

29、al control for hydraulic manifold block.On the base of the study and analysis thespeciality of the shape and structure of the hydraulic manifold block,the shape and structureare classified by the use of the group technology(GT),and then disign code on informationabout CAD/CAM for hydraulic manifold

30、block.Keywords:CAD Hydraulic manifold block Classify codeNC boring machine for processing special-shaped pin hole in pistonYang Yimin et al(18)Abstract:This paper introduces a new type NC boring machine used in the processingof specialshaped pin hole in piston.The paper discusses thoroughly the work

31、ing principle ofthe deformable boring bar utilizing piezoelectrical elements as the actuator,the mechanicalstructure and the design,and also states briefly the control of the deformable boring bar andthe NC boring machine.The NC boring machine equipped with this kind of deformable barcan bore specia

32、l-shaped pin hole in piston efficiently,and meanwhile meet the demand ofmicro-meter accuracy.Keywords:Piezoelectrical type Deformable boring bar NC boring machine Special-shaped pin hole in pistonDevelopment of extrusion molding system with PLC control for explosiveChen Kangning et al(20)Abstract:Th

33、is paper introduces the development of controlling principle machine andhydraulic system during extruding,discharging and pressure molding for viscous fluid explosive with high solid phase content by using programmable controller.Keywords:Programmable controller Explosive ExtrusionExperimental study

34、 of digital micro flow control valveJiang Wei et al(22)Abstract:This paper introduces a new type of digital micro flow control valve and itsstatic and dynamic characteristics by tests.Keywords:Digital valve Micro flow-control valve TestHydraulic balance method of pressure measurement for medicinal t

35、ablet in high speedtableting machineCao Shuping et al(24)Abstract:This paper introduces a measurement method of the pressure of medicinaltablet in high speed tableting machine,that is,to measure the upper and lower punch pres2sures in the tableting machine by using hydraulic balance system with such

36、functions as start2ing in idling pressure and protection to punch pins.Keywords:Tableting machine Medicinal tablet Hydraulic balanceResearch on electrohydraulic position synchronous system and its control methodYu Ciyuan et al(25)Abstract:This paper sets up the mathematical model of the position syn

37、chronous servosystem,analyzes mechanical parameters that influence the systems characteristic,andadoptsopen-closed loop identitycontrol theory to improve static and dynamic characteris2tic of the system.Keywords:Position synchronous system Load simulatorOpen-closed loop identitytheoryExperimental st

38、udy of single valve controlled,series and dual-asymmetric hydrauliccylinderChen Bin et al(27)Abstract:This paper studies the single servo valve controlled,series and dual-asym2metric hydraulic cylinder for yaw angle of driving wind tunnel tail-stay bearing system,and tests static and dynamic perform

39、ancesin the system.The test results proove that the ac2curacyof the system satisfies design requirements,and thus indicate the hydraulic cylinder isfeasible and the theoretical analysis is correct.Keywords:Single servo valve control Wind tunnel tail-stay bearing system Yaw an2gleDevelopment of test

40、system of power-operated superposition type weight transducerXu Chuangwen et al(29)Abstract:This paper derives a mathematical model basedon the system structure prin2ciple,and thus puts forward a simple and practicable control strategy suitable for the testsystem of the power-operated superposition

41、type weight transducer.The experimental re2sults indicate that the whole system runs reliably,and the adopted control method is simpleand praticable,with satisfying the performance requirement of the system.Keywords:Test system of weight transducer Mathematical model Control strategyResearch on hydr

42、aulic cylinder variable construction CAD systemYan Liangjun et al(32)Abstract:This article introduces a method about design of hydraulic cylinder variableconstruction CAD system.It discusses how to combine DBMS with the program of Auto2CAD drawings by ADS language,and develops a special software whi

43、ch can complete allsorts of HC from design and calculation to drawings.Keywords:Hydraulic cylinder CAD ADS language Variable construction designImplementation of auto-blanking function for hydraulic assembling drawingChen Zixia et al(34)Abstract:This paper introduces functions,principles and charact

44、eristics of auto-blanking program HTRIM for hydraulic two dimensional assembling drawing.The imple2mentation of auto-blanking for hydraulic assembling drawing by using auto LISP and ADSprogram design based on contour features of hydraulic components made in China is ac2tually anunique blanking algor

45、ithm of two dimensional graph.Keywords:Two-dimensional assembling drawing Hydraulic component Auto-blankingAnalysis on characteristics of auto-adjustment of the synchronous balancing systemfordie-forging hydraulic press controlled by On-off and proportional modeZhang Y ouwang et al(36)Abstract:This

46、paper explained the mechanism of Auto-adjustment of a synchronousbalancing systemfor Chinese-built 300MN die-forging hydraulic press.The mathematicalmodel for the synchronous balancing system controlled byon-off and proportional mode wasestablished.The characteristics of Auto-adjustment of the synch

47、ronous balancing systemcontrolled by the two modes were analyzed and compared.Keywords:Synchronous balancing system On-off control Proportional control Auto-adjustmentExperimental study of the effect of new series connected bag accumulator on pressurepulsation of oil sourceXing Keli et al(39)Abstrac

48、t:This paper analyzes the existing various pressure filters,points out theirshortcomings,and develops a new series connected bag accumulator.The theory and exper2iment verifies that it is a good pulsating attenuator and has large attenuation amplitude andwide attenuation band to pressure pulsation of oil source.Keywords:Pressure pulsation Series connected bag accumulator Spectral analysis2机床与液压