【正文】 二種情況下，電力供應(yīng)將不得不供應(yīng)更多的電力。例如，圖 1 中展示的起重機(jī)，它通過控制速度是可取的。例如：控制系統(tǒng)的機(jī)械結(jié)構(gòu)，人類的因素，功率，穩(wěn)定性和行業(yè)規(guī)則。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。Ayres 1997). The pressure pensator keeps a constant pressure drop across the main spool of the valve, which keeps the flow constant. However, the addition of a pressure pensator makes the valve more plicated 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 account for this (Back233。jbjerg Maskinfabrik (HMF) a Danish crane manufacturer. Refer to Figure 1. Figure 1 Experimental Systems in Laboratory. Left: One DOF crane model. Right: Real Mobile Hydraulic Crane As there are currently no mercially available separate meterin/separate meterout valves,two separate valves will be used instead. A sample circuit of one cylinder is shown in Figure 2. The control algorithms which control 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. Figure 2 Separate Meter In / Separate Meter Out Setup 4 CURRENT WORK Flow Control by Direct Actuation of the Spool Most flow control valves on the market today work with a pressure pensator (Andersen。論文分為五部分：需求分析； 分析當(dāng)前系統(tǒng)和他們的問題 ； 為系統(tǒng)的拓?fù)浣Y(jié)構(gòu)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(jìn)和復(fù)雜的解決辦法這可以應(yīng)用在更遙遠(yuǎn)的將來。控制系統(tǒng)有很多的影響因素。 為了避免目前系統(tǒng)中的不穩(wěn)定性，設(shè)計者采取犧牲某些功能，或者增加復(fù)雜性和成本是可取的。例如，氣缸的動作壓力是 0psi/600 psi ，與 1000psi/1600psi 是相同的。這將降低成本，即使 性能 將有所增加。另一種方式做流量控制是衡量壓力降全國閥和調(diào)整閥芯的立場，考慮到這一點 (Back233。 系統(tǒng)的性能 將低于一個復(fù)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。壓力的參考，也是控制的 PI 控制器。jbjerg Maskinfabrik (HMF) A/S 捐贈測試起重機(jī)。 好處 ，這是唯一的一次，該閥芯已越過零的 位置，當(dāng)操作者 要改變 氣缸當(dāng)運動 方向。 見圖 3 控制策略已出現(xiàn)在文獻(xiàn)中通常相當(dāng)復(fù)雜，并取決于測量氣缸的位置和速度(Elfving, Palmberg 1997。 4 當(dāng)前工作 軸向直接驅(qū)動器的流量控制 流量控制直接驅(qū)動軸線最流量控制閥在市場上今天的工作與壓力補償(Andersen。該微型電腦將使得有可能引入的靈活性閥門。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 。最后，一旦規(guī)則被滿足，穩(wěn)定性被確定，性能達(dá)到正確的水平，控制系統(tǒng)的功率功效達(dá)到最優(yōu)化。系統(tǒng)可以滿足未來的工業(yè)要求。 Palmberg, J. O. (1990). Separate Controls of Meterin and MeterOut Orifices in Mobile Hydraulic Systems, International OffHighway and Powerplant Congress and Exposition Mattila, J.。 without stability the control system can’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 mechanical structure of a mobile hydraulic crane is a very large flexible structure which has very low natural frequencies. To prevent oscillations it is necessary to keep the speed of the control system below this natural frequency or to develop a control system which can increase this frequency. The human operator also imposes limits on the control system. If the control system is too slow or too fast then it is impossible for a human operator to give it proper inputs. And finally, once the regulations have been met, stability is assured, and the performance is at the right level, the power efficiency of the control system has to be optimized. of Current Control Systems 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 are mainly hydraulic and can suffer from three main problems: cost Instability is a serious problem as it can cause injury to human operators or damage to equipment. When a system bees unstable it usually starts to oscillate violently. To avoid instability in current systems, the designers either sacrifice certain functions which are desirable,or add plexity and cost. For example, in the crane shown in Figure 1, it would be desirable to have control over the speed. But due to the safety system that cranes are required to have, standard speed control is not stable. To add speed control requires a more plex and more expensive mechanical system. The parameters of a hydraulic system, such as temperature or load force, also affect system that is stable with one set of parameters might be unstable with another set. To ensure stability over the entire operating range of the system,