外文翻譯現(xiàn)代控制理論簡(jiǎn)述

1、<p><b>　　外文資料翻譯</b></p><p>　　Introduction to Modern Control Theory</p><p>　　When differential equations are encountered, they are linearized and subjected to whatever constraint

2、s are necessary to establish useful input-output relationships. A recognition of the applicability of well-known methods in other fields of knowledge. Optimal control theory often dictates that nonlinear time varying con

3、trol law be used, even if the basic system is linear and time-invariant. When nonlinearities and time variation are present, the very basis for classical techniques is removed. So</p><p>　　With an advancing

4、technological society, there is a trend towards more ambitious goals. This also means dealing with complex system with a larger number of interesting components. The need for greater accuracy and efficiency has changed t

5、he emphasis on control system performance. The classical specifications in terms of percent overshoot, settling time, bandwidth, etc., have in many cases given way to optimal criteria such as minimum energy, minimum cost

6、, and minimum time operation. Optimization</p><p>　　The concept of state occupies a central position in modern control theory. However, it appear in many other technical and non-technical context as well. I

7、n thermodynamics the equations of state are prominently used. Binary sequential networks are normally analyzed in term of their state. In everyday life, monthly financial statements are commonplace. The President’ state

8、of the Union meesage is another familiar example.</p><p>　　In all of these examples the concept of state is essentially the same. It is a complete summary of the status of the system at a particular point in

9、 time. Knowledge of the state at some initial time t0 plus knowledge of the system inputs after t0, allows the determination of the state at a later time t1. As far as the state at t1 is concerned, it makes no difference

10、 how the initial state was attained. Thus the state at t0 constitutes a complete history of the system behavior prior to t0, insofar</p><p>　　At any fixed time the state of a system can be described by the v

11、alues of a set of variables xi called state variables. One of the state variables of a thermodynamic system is temperature and its value can arrange over the continuum of real number. In a binary network state variable c

12、an take on only two discrete values, 0 or 1. Note that the state of your cheking account at the end of the month can be represented by single number, the balance. The state of the Union can be represented by such th</

13、p><p>　　For Continuous-time system, the state is defined for all time in some interval, for example, a continually varying temperature or voltage. Discrete-time system have their state defined only at discrete

14、times, as with the monthly financial statement or the annual State of the Union message. Continuous-time and discrete-time systems can be discussed simultaneously by defining the times of interest as T. For continuous-t

15、ime system T consists of the set of times . In either case the initial time co</p><p>　　The state vector x(t) is defined only for those . At any given t, it is simply an ordered set of n numbers. However, th

16、e character of a system could change with time, causing the number of required state variables (and not just the values) to change. If the dimension of the state space varies with time, the notation could be used. It is

17、assumed here that is the same n-dimensional state space at all. </p><p><b>　　現(xiàn)代控制理論簡(jiǎn)述</b></p><p>　　當(dāng)使用微分方程時(shí)，要對(duì)其進(jìn)行線性化并受限于一定的約束條件才能建立有用的輸入-輸出關(guān)系。認(rèn)識(shí)到其他領(lǐng)域的一些有名的方法的適用性。即使系統(tǒng)是線性定常的，最優(yōu)控制理論通常

18、給出非線性時(shí)變控制律。當(dāng)系統(tǒng)存在非線性和時(shí)變特性時(shí)，經(jīng)典方法賴以存在的基礎(chǔ)就不存在了。一些成功的方法，如相平面法、描述函數(shù)法以及一些特定的方法可以改進(jìn)經(jīng)典控制理論。</p><p>　　隨著社會(huì)技術(shù)的進(jìn)步，人們總是選擇更高的目標(biāo)。這就意味著要處理復(fù)雜的具有更多相互作用的部件的系統(tǒng)。由于需要更高的精度和效率控制系統(tǒng)的性能指標(biāo)已經(jīng)發(fā)生變化。經(jīng)典的指標(biāo)如超調(diào)量、調(diào)節(jié)時(shí)間、帶寬等已經(jīng)讓位于最優(yōu)化指標(biāo)如最小能量、最小成本已

19、經(jīng)最小時(shí)間等。即使系統(tǒng)是線性定常的，最優(yōu)控制理論通常給出非線性時(shí)變控制律。</p><p>　　狀態(tài)的概念在現(xiàn)代控制理論中占據(jù)中心位置。然而其也出現(xiàn)在其他技術(shù)和非技術(shù)領(lǐng)域。在熱力學(xué)中狀態(tài)方程的概念被突出地使用。二進(jìn)制序列網(wǎng)絡(luò)通常使用狀態(tài)的術(shù)語進(jìn)行分析。在日常生活中每月的也使用財(cái)政（財(cái)務(wù)）狀況。美國(guó)總統(tǒng)的國(guó)情咨文也是一個(gè)熟悉的例子。</p><p>　　在上述所有的例子中，“狀態(tài)”的概念是基

20、本相同的。“狀態(tài)”完全就是系統(tǒng)在某個(gè)特殊時(shí)刻的“狀況”的一個(gè)總結(jié)。狀態(tài)在某個(gè)時(shí)刻t0的值再加上t0時(shí)刻的輸入的知識(shí)可以確定以后時(shí)刻t1的狀態(tài)。就t1時(shí)刻的狀態(tài)而言，它與初始狀態(tài)是如何實(shí)現(xiàn)的無關(guān)。因此，t0時(shí)刻的狀態(tài)就構(gòu)成了t0以前行為的歷史，這個(gè)歷史狀態(tài)在一定程度上影響系統(tǒng)未來的行為。當(dāng)前狀態(tài)就將過去與未來作了一個(gè)截然的劃分。</p><p>　　在任何一個(gè)固定的時(shí)刻，系統(tǒng)的狀態(tài)可以用變量集合的值xi來描述，稱為

21、狀態(tài)變量。熱力學(xué)系統(tǒng)的一個(gè)狀態(tài)變量是溫度，其值是在一個(gè)實(shí)數(shù)連續(xù)區(qū)間R變化。對(duì)于一個(gè)二進(jìn)制網(wǎng)絡(luò)狀態(tài)變量可以僅僅有兩個(gè)離散的值，0和1。你在月底帳目的平衡的狀態(tài)可以用一個(gè)數(shù)來表示。國(guó)情咨文中的狀態(tài)可以用國(guó)民生產(chǎn)總值、失業(yè)率、貿(mào)易赤字等來表示。對(duì)于本文所考慮的系統(tǒng)，狀態(tài)變量可以用任何一個(gè)標(biāo)量值（實(shí)數(shù)或復(fù)數(shù)）來表示。即。雖然有的系統(tǒng)需要用無窮多個(gè)狀態(tài)變量來表示，但是在這里我們僅僅考慮有限個(gè)數(shù)目狀態(tài)變量的系統(tǒng)。因此，狀態(tài)可以表示為n個(gè)分量的狀態(tài)向

22、量。狀態(tài)向量屬于某個(gè)域C上的狀態(tài)空間。</p><p>　　對(duì)于連續(xù)時(shí)間系統(tǒng)，狀態(tài)可以定義某個(gè)區(qū)間上的所有時(shí)間。例如，連續(xù)變化的溫度或者電壓。離散時(shí)間系統(tǒng)的狀態(tài)只定義在離散時(shí)刻。例如，每月財(cái)務(wù)狀況或者年度國(guó)情咨文。連續(xù)時(shí)間系統(tǒng)和離散時(shí)間系統(tǒng)可以通過定義時(shí)間域T來統(tǒng)一討論。對(duì)于連續(xù)時(shí)間系統(tǒng)，T由的所有實(shí)數(shù)構(gòu)成。對(duì)于離散時(shí)間系統(tǒng)，T由離散時(shí)刻集合構(gòu)成。在任何一種情形，有時(shí)，初始時(shí)刻可以為，最終時(shí)刻可以是。</p