外文翻譯---多疇模擬挖掘機(jī)的機(jī)械學(xué)和液壓學(xué)

1、<p><b>　　附錄 A</b></p><p>　　Multi-Domain Simulation:</p><p>　　Mechanics and Hydraulics of an Excavator </p><p>　　Hirokazu Araya,Masayuki Kago Shima</p><p&

2、gt;　　Mechanical Engineering Research Laboratory</p><p>　　Kobe steel,Ltd, Nishi-Kv Kobe Hyogo 6512271, Japan</p><p><b>　　Abstract</b></p><p>　　It is demonstrated how to m

3、odel and simulate an excavator with Modelica and Dymola by using Modelica libraries for multi-body and for hydraulic systems. The hydraulic system is controlled by a “l(fā)oad sensing” controller. Usually, models containing

4、3-dimensional mechanical and hydraulic components are difficult to simulate. At hand of the excavator it is shown that Modelica is well suited for such kinds of system simulations.</p><p>　　1. Introduction&l

5、t;/p><p>　　The design of a new product requires a number of decisions in the initial phase that severely affect the success of the finished machine. Today, digital simulation is therefore used in early stages t

6、o look at different concepts. The view of this paper is that a new excavator is to be designed and several candidates of hydraulic control systems have to be evaluated. </p><p>　　Systems that consist of 3-di

7、mensional mechanical and of hydraulic components – like excavators – are difficult to simulate. Usually, two different simulation environments have to be coupled. This is often inconvenient, leads to unnecessary numerica

8、l problems and has fragile interfaces. In this article it is demonstrated at hand of the model of an excavator that Modelica is well suited for these types of systems. </p><p>　　The 3-dimensional components

9、of the excavator are modeled with the new, free Modelica MultiBody library. This allows especially to use an analytic solution of the kinematic loop at the bucket and to take the masses of the hydraulic cylinders, i.e.,

10、the “force elements”, directly into account. The hydraulic part is modeled in a detailed way, utilizing pump, valves and cylinders from HyLib, a hydraulics library for Modelica. For the control part a generic “l(fā)oad sensi

11、ng” control system is used, mod</p><p>　　2. Modeling Choices</p><p>　　There are several approaches when simulating a system. Depending on the task it may be necessary to build a very precise mod

12、el, containing every detail of the system and needing a lot of information, e.g., model parameters. This kind of models is expensive to build up but on the other hand very useful if parameters of a well defined system ha

13、ve to be modified. A typical example is the optimization of parameters of a counterbalance valve in an excavator (Kraft 1996). </p><p>　　The other kind of model is needed for a first study of a system. In th

14、is case some properties of the pump, cylinders and loads are specified. Required is information about the performance of that system, e.g., the speed of the pistons or the necessary input power at the pump shaft, to make

15、 a decision whether this design can be used in principle for the task at hand. This model has therefore to be “cheap”, i.e., it must be possible to build it in a short time without detailed knowledge of particu</p>

16、<p>　　The authors intended to build up a model of the second type, run it and have first results with a minimum amount of time spent. To achieve this goal the modeling language Modelica (Modelica 2002), the Modeli

17、ca simulation environment Dymola (Dymola 2003), the new Modelica library for 3-dimensional mechanical systems “MultiBody” (Otter et al. 2003) and the Modelica library of hydraulic components HyLib (Beater 2000) was used.

18、 The model consists of the 3-dimensional mechanical construction of the e</p><p>　　3. Construction of Excavators</p><p>　　In a schematic drawing of a typical excavator under consideration is sho

19、wn. It consists of a chain track and the hydraulic propel drive which is used to manoeuvre the machine but usually not during a work cycle. On top of that is a carriage where the operator is sitting. It can rotate around

20、 a vertical axis with respect to the chain track. It also holds the Diesel engine, the hydraulic pumps and control system. Furthermore, there is a boom, an arm and at the end a bucket which is attached via a </p>

21、<p>　　Figure shows that the required pressures in the cylinders depend on the position. For the “stretched” situation the pressure in the boom cylinder is 60 % higher than in the retracted position. Not only the pos

22、ition but also the movements have to be taken into account. Figure 3 shows a situation where the arm hangs down. If the carriage does not rotate there is a pulling force required in the cylinder. When rotating – excavato

23、rs can typically rotate with up to 12 revolutions per minute – the forc</p><p>　　4. Load Sensing System</p><p>　　Excavators have typically one Diesel engine, two hydraulic motors and three cylin

24、ders. There exist different hydraulic circuits to provide the consumers with the required hydraulic energy. A typical design is a Load Sensing circuit that is energy efficient and user friendly. The idea is to have a flo

25、w rate control system for the pump such that it delivers exactly the needed flow rate. As a sensor the pressure drop across an orifice is used. The reference value is the resistance of the orifice. A</p><p>

26、　　The pump control valve maintains a pressure at the pump port that is typically 15 bar higher than the pressure in the LS line (= Load Sensing line). If the directional valve is closed the pump has therefore a stand-by

27、pressure of 15 bar. If it is open the pump delivers a flow rate that leads to a pressure drop of 15 bar across that directional valve. Note: The directional valve is not used to throttle the pump flow but as a flow meter

28、 (pressure drop that is fed back) and as a reference (resistan</p><p>　　If more than one cylinder is used the circuit becomes more complicated, see figure 5. E.g. if the boom requires a pressure of 100 bar a

29、nd the bucket a pressure of 300 bar the pump pressure must be above 300 bar which would cause an unwanted movement of the boom cylinder. Therefore compensators are used that throttle the oil flow and thus achieve a press

30、ure drop of 15 bar across the particular directional valve. These compensators can be installed upstream or downstream of the directional valves.</p><p>　　5. Model of Mechanical Part </p><p>　　I

31、n Figure 6, a Modelica schematic of the mechanical part is shown. The chain track is not modeled, i.e., it is assumed that the chain track does not move. Components “rev1”, ..., “rev4” are the 4 revolute joints to move t

32、he parts relative to each other. The icons with the long black line are “virtual” rods that are used to mark specific points on a part, especially the mounting points of the hydraulic cylinders. The light blue spheres (b

33、2, b3, b4, b5) are bodies that have mass and an inertia ten</p><p>　　The three components “cyl1f”, “cyl2f”, and “cyl3f” are line force components that describe a force interaction along a line between two at

34、tachment points. The small green squares at these components represent 1-dimensional translational connectors from theModelica.Mechanics. Translational library. They are used to define the 1- dimensional force law acting

35、 between the two attachment points. Here, the hydraulic cylinders described in the next section are directly attached. The small two spheres i</p><p>　　The jointRRR component (see right part of Figure 6) is

36、an assembly element consisting of 3 revolute joints that form together a planar loop when connected to the arm. A picture of this part of an excavator, a zoom in the corresponding Modelica schematic and the animation vie

37、w is shown in Figure 7. When moving revolute joint “rev4” (= the large red cylinder in the lower part of Figure 7; the small red cylinders characterize the 3 revolute joints of the jointRRR assembly component) the positi

38、on an</p><p>　　All components of the new MultiBody library have “built-in” animation definitions, i.e., animation properties are mostly deduced by default from the given definition of the multi-body system.

39、For example, a rod connecting two revolute joints is by default visualized as cylinder where the diameter d is a fraction of the cylinder length L (d = L/40) which is in turn given by the distance of the two revolute joi

40、nts. A revolute joint is by default visualized by a red cylinder directed along the axis</p><p>　　For every component the default animation can be switched off via a Boolean flag. Removing appropriate defaul

41、t animations, such as the “centerof- mass spheres”, and adding some components that have pure visual information (all visXXX components in the schematic of Figure 6) gives quickly a nicer animation, as is demonstrated in

42、 Figure 9. Also CAD data could be utilized for the animation, but this was not available for the examination of this excavator. </p><p>　　6. The Hydraulics Library HyLib</p><p>　　The (commercial

43、) Modelica library HyLib (Beater 2000, HyLib 2003) is used to model the pump, metering orifice, load compensator and cylinder of the hydraulic circuit. All these components are standard components for hydraulic circuits

44、and can be obtained from many manufacturers. Models of all of them are contained in HyLib. These mathematical models include both standard textbook models (e. g. Dransfield 1981, Merrit 1967, Viersma 1980) and the most a

45、dvanced published models that take the behavi</p><p>　　After opening the library, the main window is displayed (Figure 10). A double click on the “pumps” icon opens the selection for all components that are

46、needed to originate or end an oil flow (Figure 11). For the problem at hand, a hydraulic flow source with internal leakage and externally commanded flow rate is used. Similarly the needed models for the valves, cylinders

47、 and other components are chosen. </p><p>　　All components are modeled hierarchically. Starting with a definition of a connector – a port were the oil enters or leaves the component – a template for componen

48、ts with two ports is written. This can be inherited for ideal models, e.g., a laminar resistance or a pressure relief valve. While it usually makes sense to use textual input for these basic models most of the main libra

49、ry models were programmed graphically, i.e., composed from basic library models using the graphical user interface. F</p><p>　　7. Library Components in Hydraulics Circuit</p><p>　　The compositio

50、n diagram in Figure 12 shows the graphically composed hydraulics part of the excavator model. The sub models are chosen from the appropriate libraries, connected and the parameters input. Note that the cylinders and the

51、motor from HyLib can be simply connected to the also shown components of the MultiBody library. The input signals, i.e., the reference signals of the driver of the excavator, are given by tables, specifying the diameter

52、of the metering orifice, i.e. the reference va</p><p>　　8. Model of LS Control</p><p>　　For this study the following approach is chosen: Model the mechanics of the excavator, the cylinders and t

53、o a certain extent the pump and metering valves in detail because only the parameters of the components will be changed, the general structure is fixed. This means that the diameter of the bucket cylinder may be changed

54、 but there will be exactly one cylinder working as shown in Figure 1. That is different for the rest of the hydraulic system. In this paper a Load Sensing system, or LS syste</p><p>　　The hydraulic control s

55、ystem can be set up using meshed control loops. As there is (almost) no way to implement phase shifting behavior in purely hydraulic control systems the following generic LS system uses only proportional controllers.<

56、/p><p>　　A detailed model based on actual components would be much bigger and is usually not available at the begin of an initial design phase. It could be built with the components from the hydraulics library

57、but would require a considerable amount of time that is usually not available at the beginning of a project. </p><p>　　In Tables 1 and 2, the implementation of the LS control in form of equations is shown. U

58、sually, it is recommended for Modelica models to either use graphical model decomposition or to define the model by equations, but not to mix both descrip- tion forms on the same model level. </p><p>　　For t

59、he LS system this is different because it has 17 input signals and 5 output signals. One might built one block with 17 inputs and 5 outputs and connect them to the hydraulic circuit. However, in this case it seems more u

60、nderstandable to provide the equations directly on the same level as the hydraulic circuit above and access the input and output signals directly. For example, ”metOri1.port_A.p” used in table 2 is the measured pressure

61、at port_A of the metering orifice metOri1. The calculat</p><p>　　The strong point of Modelica is that a seamless integration of the 3-dimensional mechanical library, the hydraulics library and the non standa

62、rd, and therefore in no library available, model of the control system is easily done. The library components can be graphically connected in the object diagram and the text based model can access all needed variables.&l

63、t;/p><p>　　9. Some Simulation Results</p><p>　　The complete model was built using the Modelica modeling and simulation environment Dymola (Dymola 2003), translated, compiled and simulated for 5 s.

64、The simulation time was 17 s using the DASSL integrator with a relative tolerance of 10-6 on a 1.8 GHz notebook, i.e., about 3.4 times slower as real-time. The animation feature in Dymola makes it possible to view the m

65、ovements in an almost realistic way which helps to explain the results also to non-experts, see Figure 9. </p><p>　　Figure 13 gives the reference signals for the three cylinders and the swing, the pump flow

66、rate and pressure. From t = 1.1 s until 1.7 s and from t = 3.6 s until 4.0 s the pump delivers the maximum flow rate. From t = 3.1 s until 3.6 s the maximum allowed pressure is reached. Figure 14 gives the position of th

67、e boom and the bucket cylinders and the swing angle. It can be seen that there is no significant change in the piston movement if another movement starts or ends. The control system reduces</p><p>　　Figure 1

68、5 shows the operation of the bucket cylinder. The top figure shows the reference trajectory, i. e. the opening of the directional valve. The middle figure shows the conductance of the compensators. With the exception of

69、two spikes it is open from t = 0 s until t = 1 s. This means that in that interval the pump pressure is commanded by that bucket cylinder. After t = 1 s the boom cylinder requires a considerably higher pressure and the b

70、ucket compensator therefore increases the resistance</p><p>　　10. Conclusion</p><p>　　For the evaluation of different hydraulic circuits a dynamic model of an excavator was built. It consists of

71、 a detailed model of the 3 dimensional mechanics of the carriage, including boom, arm and bucket and the standard hydraulic components like pump or cylinder. The control system was not modeled on a component basis but th

72、e system was described by a set of nonlinear equations. </p><p>　　The system was modeled using the Modelica MultiBody library, the hydraulics library Hylib and a set of application specific equations. With t

73、he tool Dymola the system could be build and tested in a short time and it was possible to calculate the required trajectories for evaluation of the control system.</p><p>　　The animation feature in Dymola m

74、akes it possible to view the movements in an almost realistic way which helps to explain the results also to. </p><p><b>　　附錄B</b></p><p>　　日本機(jī)械研究實驗室，Hirokazu Araya,Masayuki Kago Shi

75、ma</p><p>　　多疇模擬：挖掘機(jī)的機(jī)械學(xué)和液壓學(xué)</p><p><b>　　概要：</b></p><p>　　通過使用用于多體和液壓系統(tǒng)的Modelica程序庫，示范通過Modelica和Dymola如何模擬和仿真挖掘機(jī)。液壓系統(tǒng)由“負(fù)載傳感”控制器控制。一般，模型包含難以模擬的三維機(jī)械和液壓組件。對于挖掘機(jī)將演示Modelica

76、有效適用于這種系統(tǒng)的仿真。</p><p><b>　　緒論</b></p><p>　　一種新產(chǎn)品的設(shè)計在開始階段需要一系列決定，這些決定對最終產(chǎn)品是否成功產(chǎn)生很大的影響。因此，今天在初始階段使用數(shù)字模擬來檢驗不同的想法。這篇論文的目的是設(shè)計一臺新的挖掘機(jī)并評估幾個備選的液壓系統(tǒng)。</p><p>　　模擬包含三維機(jī)械和液壓組件的系統(tǒng)是很難的

77、，如挖掘機(jī)，一般，兩個不同的模擬環(huán)境必須連結(jié)在一起，這一般很不方便，導(dǎo)致不必要的數(shù)字問題和破碎界面。在這篇文章中，將對挖掘機(jī)模型的開始進(jìn)行演示以證明Modelica是適合這些系統(tǒng)的。</p><p>　　挖掘機(jī)的三維組件由新近的，豐富的Modelica，聯(lián)合體程序庫來模擬，這使得可以使用鏟斗運(yùn)動循環(huán)的分析結(jié)論，并直接考慮液壓缸（也就是動力元件）的質(zhì)量。液壓部分以詳細(xì)的方法模擬，從一個用于Modelica的液壓程序

78、庫中使用泵，閥和缸。在控制部分使用一個普通的負(fù)載傳感器，由一簡單方程組模擬。這種方法得到要求的結(jié)果，并使得分析問題所需的時間限制在合理的要求內(nèi)。</p><p><b>　　2．模型選擇</b></p><p>　　模擬一個系統(tǒng)有幾種方法。根據(jù)任務(wù)的需要建立一個很精確的模型，包含系統(tǒng)的每一個細(xì)節(jié)，需要許多的信息，比如模型參數(shù)。建立這種模型很麻煩。但另一方面，如果一個定

79、義系統(tǒng)的參數(shù)需要修正，建立這種模型是很有效的。挖掘機(jī)上平衡閥參數(shù)的優(yōu)化就是一個特殊的例子。</p><p>　　對一個系統(tǒng)的初步研究需要另外一個模型，在這種情況下，泵，閥和負(fù)載的容量是具體的，需要的是關(guān)于系統(tǒng)工作的信息，例如活塞的速度，泵軸所需的輸入動力。從而判定這個設(shè)計是否符合此任務(wù)的原則要求。因此，這種模型必須是方便的，也就是，對特殊元件沒有詳細(xì)了解時能在短時間內(nèi)建立起來。</p><p&

80、gt;　　學(xué)者們打算建立第二類的一個模型，并運(yùn)行它，但在最少的時間內(nèi)得到第一類的結(jié)論，為了達(dá)到此目的，使用了建摸Modelica，Modelica模擬環(huán)境Dymola，用于三維機(jī)械系統(tǒng)的新Modelica聯(lián)合體程序庫，和液壓組件的Modelica程序庫Hylib，模型包含挖掘機(jī)的三維機(jī)械結(jié)構(gòu)，動力液壓學(xué)的詳細(xì)描述和通用的負(fù)載傳感控制器。它在Hylib的下一個版本中可應(yīng)用為一種樣本。</p><p><b&g

81、t;　　挖掘機(jī)的結(jié)構(gòu)</b></p><p>　　挖掘機(jī)它包含履帶和液壓推動裝置，液壓推動裝置用于操縱機(jī)械，但通常不在一個工作循環(huán)的時候。它的上面是供操作者坐的車廂，廂體能相對于履帶繞垂直軸旋轉(zhuǎn)，柴油發(fā)動機(jī)液壓泵和控制系統(tǒng)卻在里面，另外轉(zhuǎn)臂，動臂。在末端是鏟斗，鏟斗經(jīng)由一平面運(yùn)動回路連接到動臂上。特定的液壓缸使轉(zhuǎn)臂，動臂，鏟斗旋轉(zhuǎn)。</p><p>　　油缸所需的壓力是根據(jù)位置

82、確定的，當(dāng)在伸展開來的情況下，動臂油缸中的壓力比收縮的情況高60%。不僅位置，而且運(yùn)動也必須考慮。動臂下降的情況，如果車廂沒有旋轉(zhuǎn)，油缸則需要一個拉力，當(dāng)旋轉(zhuǎn)時，挖掘機(jī)旋轉(zhuǎn)通常能達(dá)到每分鐘12轉(zhuǎn)，則動臂油缸中的受力改變方向，此時需要一個推力。這個改變是非常重要的，因為此時活躍的油缸內(nèi)箱轉(zhuǎn)變，這必須由控制系統(tǒng)加以考慮。一個仿真模型考慮挖掘機(jī)四個自由度相互之間的聯(lián)結(jié)，每個油缸和回轉(zhuǎn)驅(qū)動使用連續(xù)載荷的簡單模型將導(dǎo)致錯誤結(jié)果。</p>

83、;<p><b>　　負(fù)載傳感器</b></p><p>　　挖掘機(jī)通常具有一臺柴油發(fā)動機(jī)，兩臺液壓馬達(dá)和三臺油缸，為這些消耗機(jī)器提供所需的液壓油源的液壓線路上不同的。一種特殊的設(shè)計是負(fù)載傳感線路，它能有效控制能量，使用方便。這種想法是使泵有一個流體速率控制系統(tǒng)，因而能準(zhǔn)確傳遞所需的流體速率。在傳感器中，使用經(jīng)過節(jié)孔而產(chǎn)生壓降的方法，孔的阻力是參考值。</p>&

84、lt;p>　　泵控制閥，使得泵出口的壓力通常比負(fù)載傳感器中的壓力高15MPA，如果方向閥關(guān)閉，則泵因此有15 MPA的壓力。如果方向閥打開，泵輸出一流體速度導(dǎo)致通過方向閥時產(chǎn)生15 MPA的壓降。注意：方向閥不是用做泵流體，而是作為一個流體儀表（反饋的壓降）和作為一個參考（阻力）。此線路對能量是有效率的，因為泵只輸出所需的流體速率，相對其他線路，油管的損失很小。</p><p>　　如果不只一個油缸使用這種

85、線路，則變得復(fù)雜。如果轉(zhuǎn)臂需要300 MPA的壓力，鏟斗需要300MPA的壓力，則泵輸出的壓力高于300MPA，這會使轉(zhuǎn)臂油缸產(chǎn)生一個不要的運(yùn)動。因此，使用補(bǔ)償器來約束油流體，因此達(dá)到通過特殊定向伐時產(chǎn)生15MPA的壓降，這些補(bǔ)償器可以安裝在定向閥的前面或后面。如果達(dá)到最大泵流體速度或泵最大壓力，則附加的閥減少容許壓力差。 </p><p><b>　　機(jī)械部分的模型</b></p&g

86、t;<p>　　機(jī)械部分假設(shè)履帶為不動的，組件“rev1…rev4”是使得相互聯(lián)系的部分運(yùn)動的旋轉(zhuǎn)關(guān)節(jié)，長黑色線的圖象是實質(zhì)是的閂，用于標(biāo)明機(jī)械部分上的特別的關(guān)節(jié)。特別是液壓油缸的固定關(guān)節(jié)，淡藍(lán)球是有質(zhì)量和慣量張量的球體，是用于模擬挖掘機(jī)的相應(yīng)部分，“cy11f.cy12f和cy13f”三個部分是線性力部件，描述兩個連接之間沿著線的力相互作用，這些部件中的小綠方格表示Modelica機(jī)械翻譯程序庫中的一維翻譯連接器，他們用

87、于表示兩連接關(guān)節(jié)之間的一維力法規(guī)。這里，將在下一部分中介紹餓液壓油缸是直接連接的?！癱y11f.cy12f和cy13f”部件圖象上的兩個小球表示有選擇的考慮兩點的質(zhì)量，在沿連接線上的連接點之間的已定距離上，這方便于模擬，只有少計算液壓油缸的質(zhì)量部分（質(zhì)量和作用中心）。</p><p>　　關(guān)節(jié)RRR組件是包含三個旋轉(zhuǎn)關(guān)節(jié)的裝配元件，其中旋轉(zhuǎn)關(guān)節(jié)在連接動臂時一起形成一片面回路。當(dāng)移動旋轉(zhuǎn)關(guān)節(jié)“rev4”（大紅油缸，

88、表示關(guān)節(jié)RRR裝配部件中三個旋轉(zhuǎn)關(guān)節(jié)的小紅缸），關(guān)節(jié)RRR部件中左右旋轉(zhuǎn)關(guān)節(jié)的連接點的位置和定位是已知的，關(guān)節(jié)RRR部件中有非線性代數(shù)回路用以計算連接點運(yùn)動時產(chǎn)生的3個旋轉(zhuǎn)關(guān)節(jié)的角度。這非線性方程系統(tǒng)在關(guān)節(jié)RRR中分解解決，如，一種快速有效的方法。</p><p>　　第一步，在沒有液壓系統(tǒng)獨立測試時，模擬挖掘機(jī)的機(jī)械部分，通過連接轉(zhuǎn)換彈簧和代替液壓油缸的合適彈簧慣量來完成。當(dāng)動力制作看起來不錯，節(jié)點上的力和扭矩

89、達(dá)到要求時，彈簧以下將介紹的液壓系統(tǒng)代替。</p><p>　　新的聯(lián)合體程序庫的所有組件有內(nèi)部的默認(rèn)定義，也就是，默認(rèn)部分都是通過聯(lián)合體系統(tǒng)中的已知定義讀用推導(dǎo)的，例如連接兩旋轉(zhuǎn)關(guān)節(jié)的閂被錯誤的理解為油缸，油缸的直徑d相對油缸的長度很?。╠=L/40）。長度反過來是由兩旋轉(zhuǎn)關(guān)節(jié)之間的距離確定的，旋轉(zhuǎn)關(guān)節(jié)被錯誤的想象為沿著關(guān)節(jié)旋轉(zhuǎn)軸的紅色油缸，挖掘機(jī)的默認(rèn)（只有一小部分采用）。</p><p&

90、gt;　　淺藍(lán)色球代表質(zhì)量作用點，想象為液壓油缸的系列力元件，通過兩種向?qū)Ψ竭\(yùn)動油缸（黃色和灰色）來定義。就如所見，不用使用一方額外的工作，動作制作有效的獲得一張模型的粗糙的照片，照片能視覺上檢測最重要的部分，如，質(zhì)量中心或連接點是否在所要求的位置上。</p><p>　　對于每個組件一Bodean旗能關(guān)閉默認(rèn)的默認(rèn)的圖。移動合適的預(yù)設(shè)圖象。例如，質(zhì)量中心球。并且添加有單純實際信息的一些組件所有visxxx組件將

91、迅速得到好看的圖象。計算機(jī)輔助制造數(shù)據(jù)也可以使用到圖象中，但這些不能用于挖掘機(jī)的試驗。</p><p>　　液壓程序庫Hylib</p><p>　　商業(yè)Modelica程序庫Hylib用于模擬泵調(diào)節(jié)孔，負(fù)載補(bǔ)償器，液壓回路缸，所有這些元件是液壓回路的標(biāo)準(zhǔn)元件，能從許多制造商獲得。Hylib中包括所有這些元件的模型。這些數(shù)學(xué)模型包含教科書上的標(biāo)準(zhǔn)模型，也包含對真實元件的運(yùn)行進(jìn)行考慮的最先進(jìn)

92、的，如果輸入口壓力下降到底于大氣壓，輸出的液體就會減小，這樣的普通泵模型就上例子。選擇一種 模型時，還有許多因素要考慮，值得一提的一點是所有模型能被原代碼水平看待，并且可以由從易得文獻(xiàn)得來的大約100個參數(shù)來證明。</p><p>　　打開程序庫后，展示了主要窗口，雙擊泵圖象打開所有元件的選項。開始或結(jié)束油流體所需要元件。為了現(xiàn)在的問題，使用帶有內(nèi)泄口和外部限定流速的液壓流體源。同樣，選擇關(guān)于閥，缸和其他元件的

93、所需模型。</p><p>　　所有組件都是分級模擬的，從連接器的確定開始（連接器是油進(jìn)入或流出元件的通口），帶有兩個口的元件模版。這能繼承下來到理想的模型。如一薄層阻力閥或釋壓閥。當(dāng)為這些基本模型使用文字上的輸入是有道理的。許多程序庫主要模型以圖形編制。由使用圖形使用者界面的基本程序庫模型組成。所有提及的元件從程序庫中選出來并分明的連接起來。</p><p>　　液壓回路中的程序庫元件&

94、lt;/p><p>　　挖掘機(jī)模型圖形組成的液壓部分，模型是從專屬的程序庫中選出，連接并輸入?yún)?shù)。注意到從Hylib來的缸和馬達(dá)能簡單連接為所示的多功能程序庫的組件。輸入信號如，挖掘機(jī)發(fā)動機(jī)的相關(guān)信號由圖框給出。使測量孔的直徑具體化。如控制流體速度的參考閥。對于挖掘機(jī)的機(jī)械部分，只要元件直接與液壓元件相連接。如液壓缸接觸的直線壓力元件。</p><p><b>　　負(fù)載傳感控制器模型

95、</b></p><p>　　在這個學(xué)習(xí)中，選擇下面的方法：模擬挖掘機(jī)的機(jī)械器件，并一定程度上詳細(xì)的模擬泵和測量閥。因為只有元件的參數(shù)將改變，一般結(jié)構(gòu)是固定的。這意味著缸筒的直徑可能改變，但確切的只有個一缸那樣工作）這個液壓系統(tǒng)其余部分是不同的，在這篇文章中使用一泵的負(fù)載傳感系統(tǒng)。但在開始設(shè)計階段還有其他的想法必須評估。例如在回轉(zhuǎn)運(yùn)動中使用兩泵或單泵。</p><p>　　根據(jù)

96、實際元件設(shè)計的全面的模型會大得多。通常在初始設(shè)計階段的開始不適用。它能由液壓程序庫中的元件建立起來，但需要相當(dāng)多的時間，這在工程的開始是行不通的。</p><p>　　一般，聯(lián)合體模型選擇使用圖形模型分解或通過方程式定義模型。但不是在一樣的模型標(biāo)準(zhǔn)上混合兩種描述形式。</p><p>　　對于LS系統(tǒng)這是不同的。因為它有7個輸入信號和5個輸出信號，建立帶有17個輸入和5個輸出的塊。并把它們

97、連接到液壓回路。但是，在這種情況下，如上面液壓回路，在一樣的標(biāo)準(zhǔn)上直接提供方程式并直接輸入輸入信號和輸出信號，看起來更加可以理解。例如，格中“metoril.port.A.p”是測量孔metoril的通口的度量壓力。LS控制器的計算值。例如，泵流體速率“pump.inport.signal[1]=” 是在泵元件的藍(lán)色矩形中的信號。</p><p>　　Modelica的重點是三維機(jī)械程序庫和非標(biāo)準(zhǔn)的無縫連接。并且

98、，因此在沒程序庫可用時，控制系統(tǒng)的模型很容易的處理。程序庫元件在目標(biāo)圖表中能連接起來，根據(jù)模型的本文能得到所需的各種變化。</p><p><b>　　仿真結(jié)果</b></p><p>　　使用Modelica模型和仿真環(huán)境Dymola建立完全模型，并轉(zhuǎn)換，編譯和模擬5秒鐘，仿真時間17秒，使用一個1.8Ghz筆記本上相對誤差10-6級的DASSI綜合器（比真實時間滿