外文翻譯--控制移動液壓起重機

1、<p><b>　　翻譯部分</b></p><p><b>　　英文原文</b></p><p>　　CONTROL OF MOBILE</p><p>　　HYDRAULIC CRANES</p><p><b>　　Marc E.</b></p>

2、<p><b>　　MÜNZER</b></p><p>　　Aalborg University</p><p>　　Institute of Energy Technology,</p><p>　　Pontoppidanstræde 101</p><p>　　DK-9220 Aalb

3、org, Denmark</p><p>　　The goal of the thesis described in this paper is to improve the control of mobile hydraulic cranes. The thesis is split into five parts: a requirements analysis, an analysis of the cur

4、rent systems and their problems, an analysis of different possibilities for system topologies, development of a new control system for the near future based on electro-hydraulic separate meter in / separate meter out val

5、ves, and finally an analysis of more advanced and complex solutions which can be applied in the</p><p>　　Key words: Mobile Hydraulic Cranes, Control Strategies, Separate Meter-in/Separate Meter-out.</p>

6、;<p>　　1 INTRODUCTION</p><p>　　The goal of the thesis described in this paper is to improve the control of mobile hydraulic cranes. A mobile hydraulic crane can be thought of as a large flexible mech

7、anical structure which is moved by some sort of control system. The control system takes its input from a human operator and translates this command into the motion of actuators which move the mechanical structure. </

8、p><p>　　The definition of this control system is purposely left vague in order not to impose any con-straints on its design. The control system consists of actuators which move the mechanical structure, a means

9、 of controlling the actuators, a means of supplying power to the actuators,and a way of accepting inputs from the operator. It is this control system which is the target of this thesis. The goal is to analyze the require

10、ments made on the control system and present guidelines for the design of new </p><p>　　The thesis will be split into five parts:</p><p>　　1.Analysis of the requirements of the control system, f

11、rom the perspective of the opera-tor, the mechanical system, efficiency, stability, and safety requirements.</p><p>　　2.Analysis of current control systems and what their problems are.</p><p>　　

12、3.Analysis of the different options for the control system: different types of actuators,different types of control strategies, and different ways of organizing components.</p><p>　　4.Presentation of a new t

13、ype of control system, which is commercially implementable. A system that will meet the needs of industry in the near future.</p><p>　　5.Analysis of more optimized systems, with higher performance, better ef

14、ficiency, more flexible control, etc. This will be less commercially applicable but will be a starting point for more research.</p><p>　　2 SECTIONS OF THE THESIS</p><p>　　2.1Requirements Analys

15、is of the Control System Before starting detailed work on developing new control systems, it is important to analyze what the exact demands are on the control system. The control system is influenced by many factors. For

16、 example: the mechanical structure it is controlling, the human operator, effi- ciency, stability, and industry regulations.</p><p>　　Industry regulations are the first requirements that have to be addressed

17、. Things like hose rupture protection and runaway load protection make a lot of demands on the control system.After regulations, stability is the next most important requirement; without stability the con-trol system can

18、’t be used. Once stability has been assured, the performance requirements of the control system have to be set. They are determined by the mechanical structure of the crane and the human operator. The mechan</p>&

19、lt;p>　　2.2Analysis of Current Control Systems</p><p>　　Before designing a new control system it is good to analyze the current control systems to find out what their problems are. Current control systems

20、are mainly hydraulic and can suffer from three main problems:</p><p>　　1.Instability</p><p>　　2.High cost</p><p>　　3.Inefficiency</p><p>　　2.2.1Instability</p>&

21、lt;p>　　Instability is a serious problem as it can cause injury to human operators or damage to equip-ment. When a system becomes unstable it usually starts to oscillate violently. To avoid insta-bility in current sys

22、tems, the designers either sacrifice certain functions which are desirable,or add complexity and cost. For example, in the crane shown in Figure 1, it would be desir-able to have control over the speed. But due to the sa

23、fety system that cranes are required to have, standard speed control i</p><p>　　The parameters of a hydraulic system, such as temperature or load force, also affect stability.A system that is stable with one

24、 set of parameters might be unstable with another set. To ensure stability over the entire operating range of the system, performance must sometimes be sacrificed at one end of the parameter range.</p><p>　

25、　2.2.2High cost</p><p>　　Current systems are purely hydraulic-mechanical, so if the user wants a certain function, the user buys a certain hydraulic-mechanical component. Because most users have different r

26、equirements, there are many different variations of the same basic component. This means that many specialized components must be manufactured rather than one standard product.This drives up the cost of components.</

27、p><p>　　2.2.3Inefficiency</p><p>　　One form of inefficiency in current systems is due to the link between the flows of the two ports of the cylinder. This is because most valves use a single spool

28、to control the flow in both ports. Because of this link, it is impossible to set the pressure levels in the two sides of the cylinder independently. Therefore, the outlet side will develop a back pressure which acts in o

29、pposition to the direction of travel, which increases the pressure required on the inlet side to maintain motion. Sinc</p><p>　　2.3Different Options for Control Systems</p><p>　　Current control

30、systems use hydraulic actuators with directional/proportional valves to control the movement. However there are many different options for controlling a cylinder. Options range from new high performance electro-hydraulic

31、 valves, to separate meter in / separate meter out (SMISMO) valves, to hydraulic bus systems, to intelligent actuators with built in power supplies, to pump based control strategies. These systems all have advantages and

32、 dis-advantages which need to be analyzed if</p><p>　　2.4 Near Future Solution</p><p>　　It is expected that even if it is proven that a completely new system topology is the optimum configuratio

33、n, the crane manufacturers and component manufacturers will not accept the new technology overnight. This will most likely take time, so an interim solution will be devel-oped.</p><p>　　This solution will be

34、 made up of micro computer controlled Separate Meter In / Separate Meter Out (SMISMO) valves (Elfving,Palmberg 1997;Jansson,Palmberg, 1990; </p><p>　　Mattila,Virvalo 1997). SMISMO valves will make it possibl

35、e to implement new control strategies which are more efficient and stable. The micro computer will make it possible to introduce flexibility to valves. Variants can be programmed in software. This eliminates the need to

36、manufacture hundreds of different variants. The crane manufacturer will be able to choose the exact functions he wants in his valve, while the component manufacturer will have to manu-facture only one valve. This will lo

37、wer</p><p>　　2.5 Analysis of Higher Performance Solutions</p><p>　　This analysis will depend on the results of the analysis of different topologies. If it is shown that pump based control is to

38、be the way of the future for example, then analysis will be per-formed in this area. Another area which will also be explored, is tool position control.</p><p>　　3 LABORATORY FACILITIES</p><p>

39、　　As the focus of this thesis is on developing control strategies that can be implemented on commercial machinery, much emphasis will be placed on experimental results. Experimental results will be obtained from two sys

40、tems. The first, a simple one degree of freedom crane,was designed as an experimental platform. The second is a real crane which was donated to the University by Højbjerg Maskinfabrik (HMF) a Danish crane manufactu

41、rer. Refer to Figure 1.</p><p>　　Figure 1 Experimental Systems in Laboratory. </p><p>　　Left: One DOF crane model. Right: Real Mobile Hydraulic Crane</p><p>　　As there are currently

42、 no commercially available separate meter-in/separate meter-out valves,two separate valves will be used instead. A sample circuit of one cylinder is shown in Figure</p><p>　　2. The control algorithms which c

43、ontrol the valves, will be programmed on a Digital Signal Processor (DSP)/Pentium dual processor system. The DSP will run the control code and the Pentium will do diagnostics and provide a graphical user interface.</p

44、><p>　　Figure 2 Separate Meter In / Separate Meter Out Setup</p><p>　　4 CURRENT WORK</p><p>　　4.1 Flow Control by Direct Actuation of the Spool</p><p>　　Most flow control

45、 valves on the market today work with a pressure compensator (Andersen;Ayres 1997). The pressure compensator keeps a constant pressure drop across the main spool of the valve, which keeps the flow constant. However, the

46、addition of a pressure compensator makes the valve more complicated than a simple single spool valve. Another way of doing flow control is to measure the pressure drop across the valve and adjust the spool position to ac

47、count for this (Backé; Feigel 1990). This i</p><p>　　The concept is very simple, spool position is calculated from the Bernoulli equation using the pressure drop across the spool and a reference flow.&l

48、t;/p><p>　　Even though this is a simple equation, it is not easy to implement. The accuracy of the flow control is dependent on the precision of the position sensors and of the pressure transducers.Noise on the

49、 pressure or the position signals can cause stability problems. Filtering the noise,introduces delays in the control which can also affect stability. In addition the Bernoulli equation is not followed exactly over the en

50、tire operating range of the valve, so it may be nec-essary to store the valve cha</p><p>　　4.2 Cylinder Control Strategy</p><p>　　To control a hydraulic cylinder, the strategy has to be able to

51、handle four different situations depending on the directions of the load and the velocity of the cylinder. Refer to Figure 3 The control strategies that have appeared in the literature are usually quite complex and depe

52、nd on measurements of the cylinder position and velocity (Elfving,Palmberg 1997;Mattila;Virvalo 1997). They are also based on rather complex control algorithms. It is the goal of this thesis to start with a control s<

53、/p><p>　　Figure 3 Different Situations in Crane Operation</p><p>　　Another feature which needs to be acknowledged when designing a control strategy, is thetype of valve used. Mobile hydraulic valve

54、s demand low leakage and since most mobilevalves are spool valves, they usually have large overlaps. In addition, to make the cost of thevalve acceptable to industry, the actuation stage on the spool is usually quite slo

55、w. This com-bination of large overlap and slow actuation makes it hard to implement many of the strate-gies that have been presented. Pressure control</p><p>　　One example of a new strategy which is simple a

56、nd robust is described as follows. Flow con-trol is implemented on the inlet side and pressure control is implemented on the outlet side.The flow control is based on the Bernoulli equation. Pressure control is done by a

57、PI control-ler which maintains a low constant pressure to increase the efficiency and prevent cavitation.To work around large overlaps and slow actuation stage, the pressure controller only does meter out control. This m

58、eans that if </p><p>　　At the time of writing this paper the initial experimental tests had been performed on the real crane shown in Figure 1 . Stability was not achieved because the crane is equipped with

59、a load holding valve. However, the load holding valve will be replaced with a pilot operated check valve, which should make it possible to stabilize the system. In current systems, the load holding valve serves two funct

60、ions, load holding and runaway load protection. Due to the use of a SMISMO valve setup, the runa</p><p>　　Figure 4 Controller Strategy for Lowering of Load</p><p>　　5 CONCLUSION</p><

61、p>　　Even though not much experimental work has been finished, a good start has been made and initial tests have been promising. The outline of the thesis has been developed and organized in a logical manner. The work

62、is split into five parts, requirements analysis, analysis of cur-rent systems, analysis of different topologies, development of a near future solution, and development of a more optimum solution. At the end of the thesis

63、, the control of mobile hydraulic cranes will have been improved.</p><p>　　6 ACKNOWLEDGEMENTS</p><p>　　This project is being funded in part by Danfoss Fluid Power A/S. The author would also lik

64、e to thank Højbjerg Maskinfabrik (HMF) A/S for the donation of the test crane.</p><p>　　7 REFERENCES</p><p>　　Andersen, B. R.; Ayres, J. L. (1997). Load Sensing Directional Valves, Current

65、 Technology and Future Development, The Fifth Scandinavian International Conference on Fluid Power</p><p>　　Backé, W.; Feigel, H. (1990). Neue Möglichkeiten Beim Elektrohydraulischen Load-Sens-ing,

66、 O+P Ölhydraulik und Pneumatik 34</p><p>　　Elfving, M.; Palmberg, J. O. (1997). Distributed Control of Fluid Power Actuators -</p><p>　　Experimental Verification of a Decoupled Chamber Pres

67、sure Controlled Cylinder, 4th Inter-national Conference on Fluid Power</p><p>　　Jansson, A.; Palmberg, J. O. (1990). Separate Controls of Meter-in and Meter-Out Orifices in Mobile Hydraulic Systems, Internat

68、ional Off-Highway and Powerplant Congress and Exposition</p><p>　　Mattila, J.;Virvalo, T. (1997). Computed Force Control of Hydraulic Manipulators, 5th Scandinavian International Conference On Fluid Power&l

69、t;/p><p><b>　　中文譯文</b></p><p><b>　　控制移動液壓起重機</b></p><p>　　Marc E. MÜNZER</p><p><b>　　奧爾堡大學</b></p><p><b>　　能源技術

70、研究所</b></p><p>　　Pontoppidanstræde 101</p><p>　　丹麥奧爾堡DK-9220</p><p>　　Email: mmun@iet.auc.dk</p><p>　　在這篇論文中論題描述的目的是改進控制移動液壓起重機。論文分為五部分：需求分析；分析當前系統(tǒng)和他們的問題；為系統(tǒng)

71、的拓撲結構分析不同的可能性；基于對電液伺服單獨的輸入儀表/單獨的輸出儀表的閥門， 為不久的將來發(fā)展一個新的控制系統(tǒng)；最后分析更先進和復雜的解決辦法這可以應用在更遙遠的將來。論文工作將被用在工業(yè)協(xié)作中，因此論文將比純粹對論文焦點有更多對工業(yè)焦點。</p><p>　　關鍵詞：移動液壓起重機；控制策略；單獨的輸入輸出儀表； </p><p><b>　　1導 言</b>

72、</p><p>　　在這篇論文中論題描述的目的是改進控制移動液壓起重機。移動液壓起重機可認為是作為一個大型靈活的機械結構，這種機械結構被提出某種形式的控制系統(tǒng)。這種控制系統(tǒng)由人類工作者輸入并且轉換命令成為移動機械機構傳動裝置的動作。</p><p>　　控制系統(tǒng)的定義是故意留下模糊，目的是不加任何約束在它的設計上。該控制系統(tǒng)作動是移動的機械結構，一種控制傳動裝置的方法，一種給傳動裝置供電

73、的方法，和接受操作者的輸入的方法。這就是控制系統(tǒng)，這篇論文的對象。目標是要分析作出關于控制系統(tǒng)和現(xiàn)有的指導方針的要求，以供設計新的控制系統(tǒng)。</p><p>　　論文將分成五個部分：</p><p>　　1.對控制系統(tǒng)要求的分析，從操作者的觀點，機械系統(tǒng)，功率，穩(wěn)定性和安全要求這些方面。</p><p>　　2.分析目前的控制系統(tǒng)和他們的問題</p>

74、<p>　　3.為控制系統(tǒng)分析不同的選項：不同類型的傳動裝置，不同類型的控制策略和不同方式的組織構成。</p><p>　　4.介紹來一種新型的商業(yè)可行的控制系統(tǒng)。系統(tǒng)可以滿足未來的工業(yè)要求。</p><p>　　5.分析更多的優(yōu)化系統(tǒng)，如更高的性能，提高效率，更靈活的控制等。這將會減少商業(yè)適用但是將是更多研究的一個起點。</p><p><b>

75、;　　2 論文部分</b></p><p>　　2.1控制系統(tǒng)的需求分析</p><p>　　對分析控制系統(tǒng)的嚴格要求來說.發(fā)展新的控制系統(tǒng)開始之前的詳細工作是重要的?？刂葡到y(tǒng)有很多的影響因素。例如：控制系統(tǒng)的機械結構，人類的因素，功率，穩(wěn)定性和行業(yè)規(guī)則。</p><p>　　行業(yè)法規(guī)是第一要求，必須加以解決。像對破裂軟管的保護和運轉負荷的保護采取的措施

76、是控制系統(tǒng)的許多要求。規(guī)則之后，穩(wěn)定性是下一個最重要的要求。沒有穩(wěn)定性，不能使用控制系統(tǒng)。穩(wěn)定性的確認，樹立了控制系統(tǒng)的執(zhí)行要求。起重機的機械結構和人類操作者決定了它們。移動液壓起重機的結構是一個有非常低的固有頻率的大型的靈活結構。為了預防震動，它必須保持控制系統(tǒng)的速度在正常的頻率或者去發(fā)展能增加這個頻率的控制系統(tǒng)。人類工作者也施加影響控制系統(tǒng)的限制。如果控制系統(tǒng)是太慢或者太快，那么人類操作者不可能對它合適的輸入。最后，一旦規(guī)則被滿足，

77、穩(wěn)定性被確定，性能達到正確的水平，控制系統(tǒng)的功率功效達到最優(yōu)化。</p><p>　　2.2當前控制系統(tǒng)的分析</p><p>　　在新的控制系統(tǒng)設計之前最好分析當前的控制系統(tǒng)來發(fā)現(xiàn)它們的問題。</p><p>　　目前控制系統(tǒng)主要是水壓和遭受的三個主要的問題：</p><p><b>　　1.不穩(wěn)定性</b></

78、p><p><b>　　2.高成本</b></p><p><b>　　3.無效率</b></p><p><b>　　2.2.1不穩(wěn)定性</b></p><p>　　不穩(wěn)定是一個嚴重的問題，因為它可以造成傷害人類的操作者或損壞的設備。當一個系統(tǒng)變得不穩(wěn)定，這通常開始激烈的振蕩。為

79、了避免目前系統(tǒng)中的不穩(wěn)定性，設計者采取犧牲某些功能，或者增加復雜性和成本是可取的。例如，圖1中展示的起重機，它通過控制速度是可取的。但是由于起重機安全系統(tǒng)的要求，標準速度的控制是不穩(wěn)定的?？刂扑俣鹊脑黾右蟾撠熁蛘吒喟嘿F的機械系統(tǒng)。</p><p>　　水壓系統(tǒng)的參數(shù)，例如溫度和荷載力量，也影響穩(wěn)定性。一個系統(tǒng)調整參數(shù)的穩(wěn)定可能對另一個參數(shù)不穩(wěn)定。為了確保完整系統(tǒng)范圍對穩(wěn)定性，性能可能在某個參數(shù)范圍的目標中犧

80、牲掉。</p><p><b>　　2.2.2高成本</b></p><p>　　目前系統(tǒng)是純粹的液壓機械，所以使用者想要某一功能，那么使用者要買一個液壓機械組件。因為大多數(shù)的用戶有不同的要求，相同的基本組成就有許多不同的版本。這意味著，許多專門組成部分必須制造出不是一個標準的產(chǎn)品。這使構成的成本上升。</p><p><b>　　2

81、.2.3無效率</b></p><p>　　由于在氣缸兩個端口之間的連接物流動，在目前系統(tǒng)中存在一種低效率形式。這是因為大多數(shù)閥門使用一個單一的后臺控制流在兩個端口。因為這個環(huán)節(jié)，這是不可能設置的壓力水平在氣缸獨立的兩邊。因此，出口方將制定一個回壓力的行為，在反方向行進，從而增加維持運動進口邊的要求壓力。由制動裝置產(chǎn)生的力量是與兩邊之間不同的壓力成比例，氣缸的實際壓力是不影響氣缸的動作。例如，氣缸的動

82、作壓力是0psi/600 psi ，與1000psi/1600psi是相同的。然而，在第二種情況下，電力供應將不得不供應更多的電力。這額外的電力是浪費。</p><p>　　2.3不同選擇的控制系統(tǒng)</p><p>　　目前的控制系統(tǒng)使用的液壓致動器與定向/比例閥控制運動。不過有很多不同的選項控制氣缸。</p><p>　　選擇范圍從新型高性能電-液壓閥，來單獨的輸

83、入儀表/單獨的輸出儀表(SMISMO)的閥門，液壓總線系統(tǒng)，智能驅動器內置在電源供應器，泵基于控制策略。這些系統(tǒng)都有優(yōu)點和缺點，需要加以分析，如果最優(yōu)化的解決辦法是選擇。</p><p>　　2.4不久的將來解決方案</p><p>　　可以預料，即使是證明，一個完全新系統(tǒng)的拓撲結構是最優(yōu)配置中，起重機的制造商和部件制造商將不會接受持續(xù)一夜的新科技。這將最有可能需要一定的時間，使一個臨時解

84、決辦法，將得到開發(fā)。</p><p>　　這個解決方案將由微型電腦控制的單獨的輸入儀表/單獨的輸出儀表(SMISMO)的閥門（Elfving, Palmberg 1997; Jansson, Palmberg, 1990; Mattila,Virvalo 1997）SMISMO閥門，將使得有可能實施新的控制策略是更有效率和更穩(wěn)定。該微型電腦將使得有可能引入的靈活性閥門。變值可以編程軟件。這消除了需要制造數(shù)百種不同

85、的變值。起重機制造商將能夠選擇的確切功能，他希望在他的閥門，而組件制造商將不得不生產(chǎn)上只有一個閥門。這將降低成本，即使性能將有所增加。</p><p>　　2.5分析了更高的性能的解決方案</p><p>　　這項分析將取決于有關的分析結果不同的拓撲結構。如果證明即泵基于控制是要方式，未來舉例來說，分析，然后將表現(xiàn)在這方面的工作。另一個領域也將加以探討，是工具的位置控制。</p>

86、;<p><b>　　3 實驗室設施</b></p><p>　　作為重點，這一論斷是對發(fā)展中國家的控制策略可以實施對商業(yè)機械，許多重點將放在實驗結果。實驗結果將所得的兩種制度。第一，一個簡單的自由度，起重機，目的是作為一個實驗平臺。第二是一個真正的起重機，其中由HMF一個丹麥制造商捐獻給了大學。參考圖1 </p><p>　　由于目前并沒有商業(yè)上可

87、用單獨的輸入儀表/單獨的輸出儀表的閥門, 兩個單獨的閥門將被用于代替。一個氣缸的采樣電路如圖2所示?？刂崎y的控制算法，將程序是一種數(shù)字信號處理器（ DSP ） /奔騰雙處理器系統(tǒng)。該DSP將運行控制代碼和Pentium將做診斷，并提供一個圖形用戶界面。</p><p><b>　　4 當前工作</b></p><p>　　4.1軸向直接驅動器的流量控制</p&g

88、t;<p>　　流量控制直接驅動軸線最流量控制閥在市場上今天的工作與壓力補償(Andersen;Ayres 1997)。壓力補償器保持恒定的壓力下降，全國主要閥芯的閥，不斷流不斷。不過，除了一個壓力補償，使閥復雜得多，一個簡單的單滑閥。另一種方式做流量控制是衡量壓力降全國閥和調整閥芯的立場，考慮到這一點(Backé; Feigel 1990)。這不是一個新的構思，但一直沒有得到實施，因為在商業(yè)上的成本高昂，壓力傳

89、感器和微控制器。不過，與目前的下降，成本的微控制器和壓力傳感器這種想法是現(xiàn)在在商業(yè)上可行的。</p><p>　　這個概念非常簡單，后臺的立場是計算從伯努利方程使用壓力降全國閥芯和參考設計流程。</p><p>　　即使這是一個簡單的方程式，這是不容易落實。精確的流量控制是依賴于高精度的位置傳感器和壓力傳感器。噪音對壓力或立場的信號可以造成穩(wěn)定性問題。過濾噪音，介紹了延誤，在控制也可以影響

90、穩(wěn)定。此外，該伯努利方程是沒有遵循正是在整個。閥門的全部運行范圍，因此它可能是必要的儲存閥的特點作為一個數(shù)據(jù)表或開發(fā)一個更復雜的方程。</p><p>　　4.2氣缸的控制策略</p><p>　　控制液壓缸，這個策略，以便能夠處理四種不同的情況，依賴負荷的趨勢和氣缸的速度。見圖3</p><p>　　控制策略已出現(xiàn)在文獻中通常相當復雜，并取決于測量氣缸的位置和速度

91、(Elfving, Palmberg 1997;Mattila; Virvalo 1997)他們基于同樣的基礎上，而不是復雜的控制算法。它的目標是這一論斷開始與控制策略是基于簡單的PI控制器和不作任何要求的位置和速度的氣缸。系統(tǒng)的性能將低于一個復雜的控制策略，但它可能更容易商業(yè)實施，因為它不需要特殊的傳感器并且更容易被一般的工程師理解。</p><p>　　另一個特點，需要予以承認，在設計時控制策略，是這類型閥的

92、使用。移動液壓閥的需求，低漏電，并由于大多數(shù)流動閥閥芯閥門，他們通常有大的重疊。此外，為了在工業(yè)上接受閥門的成本，沖動進程通常是相當緩慢。這一組合的大型重疊和緩慢的驅動使得它難以落實的許多戰(zhàn)略已提交。力量控制變得困難，特別是當有一個重疊和一個緩慢的制動裝置。</p><p>　　其中一個例子是一項新戰(zhàn)略，這是簡單的和穩(wěn)健的描述如下。流量控制是實施對進口方和壓力控制是實施對出口的一面。流量控制的基礎上，伯努利方程。

93、壓力控制是由PI控制器保持低恒定的壓力，提高工作效率和防止汽蝕。要解決大的重疊和緩慢的驅動階段，壓力控制器不僅是儀表輸出控制。這意味著，如果控制器的意愿，以提高壓力，它不能增加流量，以圓柱，它只能減少輸出端口開口。好處，這是唯一的一次，該閥芯已越過零的位置，當操作者要改變氣缸當運動方向。這種情況下，負載力和速度都在同一方向，這一戰(zhàn)略已經(jīng)被修改。在這種情況下，壓力范圍，壓力控制器，在出口增加的一個值，其中反對負荷的力量。壓力是增加參考當它

94、注意到的壓力，進氣一邊是呈下降趨勢。壓力的參考，也是控制的PI控制器。示意圖模型控制器的系統(tǒng)負載降低的情況如圖4所示</p><p>　　寫這本書的初步實驗測試的同時，起重機如圖1所示已完成任務。穩(wěn)定是沒有達到，因為起重機是配備了負荷控股閥。不過，負荷控股閥將取代一個試點運作，止回閥，應使人們有可能穩(wěn)定系統(tǒng)。在目前的制度下，負載控股閥服務兩項職能，負載控股和失控的負荷保護由于使用了smismo閥安裝，離家出走的負

95、荷保護是建成的控制策略，因此，唯一的功能是必要的負荷控股閥的執(zhí)行是負載舉行。液體單向閥門將能夠做到這一點，沒有加入復雜的動力學，這顛覆了系統(tǒng)的穩(wěn)定性。</p><p><b>　　5 結論</b></p><p>　　即使沒有太大的試點工作已經(jīng)完成，一個好的開始，已取得初步測試已大有希望的。綱要的論文已被發(fā)達國家和有組織的在一個合乎邏輯的方式。工作分成五個部分，需求分

96、析，分析現(xiàn)行制度，分析不同的拓撲結構，發(fā)展一個不久的將來解決辦法，和發(fā)展一個更優(yōu)化的解決方案。在去年底的論文，控制移動液壓起重機將得到改善。</p><p><b>　　6 鳴謝</b></p><p>　　這個項目由丹佛斯流體動力A/S提供部分資金。作者也想感謝Højbjerg Maskinfabrik (HMF) A/S捐贈測試起重機。</p>