【正文】 39 附錄 一 英文科技文獻(xiàn)翻譯 英文原文 ： Linearized Dynamic Models EXAMPLES AND CLASSIFICATIONS OF CONTROL SYSTEMS Control systems exist in a virtually infinite, both in type of application and level of sophistication. The heating system and the water heater in a house are systems in which only the sign of the difference between desired and actual temperatures is used for control. If the temperature drops below a set value, a constant heat is switched on, to be switched off again when the temperature rises above a set maximum. Variations of such relay or onoff control systems, sometimes quite sophisticated, are very mon in practice because of their relatively low cost. In the nature of such control systems, the controlled variable will oscillate continuously between maximum and minimum limits. For many applications the control is not sufficiently smooth or accurate. In the Power steering of a car, the controlled variable or system output is the angle of the front wheels, it must follow the system input, the angle of the steering wheel, as closely as possible but at a much higher Power level. In the Process industries, including refineries and chemical plants, there are many temperatures and level to be held to usually constant values in the presence of various disturbance. of an electric power generation Plant, controlled values of voltage and frequency are outputs, but inside such a plant there are again many temperatures, levels, pressures, and, other variables to be controlled. In aerospace, the control of aircraft, missiles, and satellites is an area of often very advanced system. One Classification of control systems Is the following: 1. Process control or regulator systems: The controlled variable, or output, must be held as close as possible to a usually constant desired value, or input, despite any disturbances. 2. Servomechanisms: The input varies and the output must be made to follow it as closely as possible. Power steering is One example of the second class, equivalent to systems for positioning control surfaces on aircraft. Automated manufacturing machinery, such as numerically controlled machine tools, uses servos extensively for the control of positions or speeds. This last example brings to mind the distinction between continuous and discrete systems. The latter are inherent in the use of digital puters for control. The classification into linear nonlinear control systems should also be mentioned at this point. Analysis and design are in general much simpler for the former, to which most of this book is devoted. Yet most systems bee nonlinear if the variables more over wide enough ranges. The importance in practice of linear techniques relies on linearization based on the assumption that the variables stay close enough to a given operating point. OPENLOOP CONTROL AND CLOSEDLOOP CONTROL To introduce the subject, it is useful to consider an example. In , let it be desired to maintain the actual water level in the tank as close as possible to a desired level. The desired level will be called the system input, and the actual level the controlled or system output. Water flows from the tank via valve Vo and enters the 40 tank a supply via a control valve Vc. The control valve is adjustable, either manually or by some type of actuator. This may be an electric motor or a hydraulic or pneumatic cylinder. Very often it would be pneumatic diaphragm actuator, indicated in Fig 2. Increasing the pneumatic pressure above the diaphragm pushes it down against a spring and increases valve opening. In this form of Control, the valve is adjusted t0 make output c equal to input r, but not, readjusted continually to keep the two equal. Open loop control, with certain safeguards added is very mon, for example, in the context of sequence control, that is, guiding a process through a sequence of predetermined steps. However, for systems such as the one at hand, this form of control will normally not yield high performance. A difference between input and output, a system error e = rc would be expected to develop, due to two major effect: 1. Disturbances acting on the system 2. Parameter variation of the system These are prime motivations。還要感 謝我們 03 電氣所有的同學(xué)，正是可愛的你們，我的大學(xué)生活才如此的豐富多彩！ 最后要感謝的，是 我的家人，同時(shí)將這篇論文送給他們。同時(shí) 也給與我們很多幫助。正是由于我們的努力，整個(gè)設(shè)計(jì)才能進(jìn)行的那么順利。 其次，我要感謝的是我的同伴 —— 陶睿同學(xué)，本系統(tǒng)的設(shè)計(jì)由我們共同完成。在論文的編寫過(guò)程中，他給我提出寶貴的意見，并且給與細(xì)致的指導(dǎo)。 首先，我要向我的指導(dǎo)老師致以由衷的感謝和誠(chéng)摯的敬意，他的指導(dǎo)為我們提供了設(shè)計(jì)的主題思想，在編程過(guò)程中，他在自己的繁忙工作之余指導(dǎo)我們，檢查并排除了我們?cè)O(shè)計(jì)過(guò)程中的諸多漏洞。這正是該項(xiàng)目的難點(diǎn)，也是我們繼續(xù)要開發(fā)研究的。 要真正實(shí)現(xiàn)基于網(wǎng)絡(luò)的遠(yuǎn)程實(shí)驗(yàn)、仿真、數(shù)據(jù)分析等，非常困難。大大減少實(shí)驗(yàn)室的投入，降低辦學(xué)成本。這將使更多的學(xué)生可以進(jìn)行必要的實(shí)驗(yàn)，彌補(bǔ)了實(shí)驗(yàn)設(shè)備、仿真軟件的缺乏，改善了學(xué)校的實(shí)驗(yàn)狀況，提高實(shí)驗(yàn)的開出率。我需要一個(gè)基于網(wǎng)絡(luò)平臺(tái)的遠(yuǎn)程實(shí)驗(yàn)、仿真系統(tǒng)。 當(dāng)然在這次畢業(yè)設(shè)計(jì)中我們也有許多不足之處：由于在畢業(yè)設(shè)計(jì)初期全局考慮不夠周全，把實(shí)驗(yàn)報(bào)告的生成考慮的不夠細(xì)致，導(dǎo)致在最后生成實(shí)驗(yàn)報(bào)告時(shí)，不得不把實(shí)驗(yàn) 報(bào)告部分安排在每個(gè)分析實(shí)驗(yàn)的界面之下；本來(lái)打算把編寫的軟件 36 進(jìn)行打包生成可執(zhí)行文件，由于時(shí)間倉(cāng)促也沒有實(shí)現(xiàn)；關(guān)于 MATLAB 與 C 語(yǔ)言等其他高級(jí)語(yǔ)言的接口問(wèn)題也沒有涉及，總之本實(shí)驗(yàn)系統(tǒng)也還有較多的需要完善的地方。 對(duì)于給 定被 控系統(tǒng)，按照預(yù)先給定系統(tǒng)的參數(shù)繪制出系統(tǒng)的根軌跡圖，并按照給定的瞬態(tài)性能指標(biāo)要求用根軌跡分析法設(shè)計(jì)串聯(lián)校正補(bǔ)償器以及求出校正前后系統(tǒng)的傳遞函數(shù)。 可以用于分析系統(tǒng)，而且指出了改善系統(tǒng)性能的有效途徑。 根軌跡法是一種求解閉環(huán)特征方程根的簡(jiǎn)便圖解方法，它根據(jù)系統(tǒng)的開環(huán)傳遞函數(shù)極點(diǎn)和零點(diǎn)的分布，依據(jù)一些簡(jiǎn)單的規(guī)則，研究開環(huán)系統(tǒng)某一參數(shù)變化時(shí)，閉環(huán)系統(tǒng)極點(diǎn)和零點(diǎn)在 s 平面上的軌跡 。此次畢業(yè)設(shè)計(jì)建模這一塊我們重在介紹如何 通過(guò) MATLAB 工具求取系統(tǒng)每個(gè)環(huán)節(jié)傳遞函數(shù)，然后通過(guò)一定的算法得到總傳遞函數(shù)。我還了解了 MATLAB 的控制系統(tǒng)工具箱，它是 MATLAB 中的一個(gè)重要的領(lǐng)域型工具箱，主要用于線性定常系統(tǒng)的分析、設(shè)計(jì)與仿真。 通過(guò)這次畢業(yè)設(shè)計(jì)機(jī)會(huì)我強(qiáng)化了自己的自動(dòng)控制理論，學(xué)會(huì)了用 MATLAB進(jìn)行控 制理論和控制工程研究的基本思路和方法。 35 5 總結(jié)和展望 本次畢業(yè)設(shè)計(jì)我們用 MATLAB 設(shè)計(jì)了《自動(dòng)控制原理》虛擬實(shí)驗(yàn)系統(tǒng)，主要設(shè)計(jì)友好的人機(jī)界面供學(xué)生做實(shí)驗(yàn)使用。 我們由實(shí)驗(yàn)報(bào)告生成模塊中知道：實(shí)驗(yàn)報(bào)告包括實(shí)驗(yàn)原 理與目的（圖 ）、實(shí)驗(yàn)步驟（圖 ）、和實(shí)驗(yàn)結(jié)果（圖 和圖 ）。 33 在此，我們以根軌跡實(shí)驗(yàn)為例簡(jiǎn)要地說(shuō)明本虛擬實(shí)驗(yàn)系統(tǒng)在《自動(dòng)控制原理》實(shí)驗(yàn)中的應(yīng)用，展示一下本虛擬實(shí)驗(yàn)系統(tǒng)的功能。保存下來(lái)的 模型 參數(shù)可用于重復(fù)進(jìn)行系統(tǒng)分析、設(shè)計(jì)與仿真 ；保存下來(lái)的輸人數(shù)據(jù)、設(shè)計(jì)與仿真結(jié)果可以作為撰寫實(shí)驗(yàn)報(bào)告的素材。對(duì)用戶而言，操作簡(jiǎn)單易學(xué)且無(wú)須編程，參數(shù)輸人與修改是活．具有多次或重復(fù)仿真運(yùn)行的控制能力，可 以 顯示校正前后系統(tǒng)的特性曲 線，能很直觀漂亮地繪 制出控制系統(tǒng)的階躍響應(yīng)曲線、伯德圖、乃氏 圖和根軌跡圖．這些很強(qiáng)的交互能力使其在自動(dòng)控制原理的實(shí)驗(yàn)中可以發(fā)揮理想的效果。該系統(tǒng)是中文界面， 具有人機(jī)界面友好、結(jié)果可視化的優(yōu)點(diǎn)。 最后生成新的 M 文件 : 文件 ,在運(yùn)行該文件 ,得到圖的主界面 圖 虛擬實(shí)驗(yàn)系統(tǒng)的主界面 32 4 系統(tǒng)設(shè)計(jì)成果及實(shí)驗(yàn)舉例 系統(tǒng)設(shè)計(jì)成果 經(jīng)過(guò)三個(gè)月的努力，我們建立了一個(gè)用戶界面良好的《自動(dòng)控制原理