外文翻譯---自動控制基礎(chǔ)

1、<p>　　附錄 英文資料及其譯文</p><p>　　CHAPTER 1 Basis of the automatic control</p><p>　　1.       Out line </p><p>　　This device is temperature control expe

2、rimental device of temperature, lever, pressure , that are the most common control subject for water treatment plants, chemical factories and power plants. </p><p>　　At the experiment of automatic control,

3、it is very important to keep the balance of system. Automatic control system is composed of control subjects and to keep control device. Especially process control has many control subjects to keep self-balance, so the e

4、xperimental results is conducted with balance condition.</p><p>　　This experimental device experiments about the relation of input signal and output signal to keep the balance (System characteristics) at the

5、 cascade experiment and fixed command control, also experiments on dynamic characteristic (Balance condition without time variation),static characteristic (Balance condition considerating time variation).</p><

6、p>　　And you record the change of control amount which was input handling amount or establishment of characteristic experiment. These typical response can be thought step response . You experiment optimum control exper

7、iment , fixing P . I. D constant of control device</p><p>　　, relating this step response.</p><p>　　2.       Process control </p><p>　　Process control

8、keeps the balance of the system, automatically correcting toward deviation, and compares every variable to operating toward deviation, and compares every variable to operation condition of industrial process of flux, tem

9、perature, surface, pressure, etc with the established goal.</p><p>　　Process control is decided into closed loop and Open loop control.</p><p>　　3.       Kinds of a

10、utomatic control </p><p>　　Control is composed of detection (measurement), comparison, judgment, operation and manual control is done by man’s hand and automatic control is done by measure or adjuster or oth

11、er machinery.</p><p>　　At present, automatic control is taken at the many plants . Moreover , we cannot think plant control without automatic control.</p><p>　　Kinds of automatic control is deci

12、ded like below.</p><p>　　Automatic control Open loop control Feed forward control </p><p>　　Sequential control</p><p>　　Closed loop controlFeedback control<

13、;/p><p>　　3-1 . Feed back control </p><p>　　Feed back control detects (measure) compares , judges ,operates ,automatically. And it measures the results every moment , and corrects automatically if

14、 there is any differential between the desired value (set value).</p><p>　　Feed back control is one of the main process control . </p><p>　　This is the control that detecting (measuring) the re

15、sults (Control amount: tank water lever ) with differential transmitter, and comparing the value with the set water lever and correct the deviation(Opening operation flow control of the control value)</p><

16、p>　　Like the above, feed back control automatically does the movement of measurement(detection) comparison calculation modernfication. Feed back system has the element of doing these functions.</p><p>　　A

17、t the diagram 3-1 block line diagram it is the closed loop and it transmitted the correcting signal of the opposition toward the process flow.</p><p>　　Block line diagram: Indicating the constructing element

18、 of control system in block , and connecting the line expressing the signal flow.</p><p>　　Signal :The amount being used for transmit the information</p><p>　　3-2.Feed forward control</p>

19、<p>　　Feed forward control is the control method doing necessary correct movement before the influence appears to the control system , when disturbance enters into the control system.</p><p>　　At feed

20、back control, it starts correct movement to erase the deviation after the influence by disturbance appears, so in case of sudden change of disturbance or set value, then control disorders transiently and arises many prob

21、lems.</p><p>　　Feed forward control breaks down this weak point.</p><p>　　At feed forward control, results of the controller is not done feedback and becomes open-loop control, not being close-l

22、oop control. Accordingly, in case of feed back control, the relation between cause and effect of disturbance and the results of control must be understood well. That is ,relation of influence to the control amount toward

23、 load change, and operating amount needed to compensate it should be clear.</p><p>　　But it is generally difficult. In many cases it is difficult that all the disturbance is detected, and to get the perfect

24、process model in actual process.</p><p>　　Moreover it is difficult to avoid constant deviation, so it is used combined with feed back control.</p><p>　　3-3 Sequence control</p><p>　

25、　Sequence control processes the fixed process in advance step by step. This sequence control is used in neon signs, vending machines, or electric washing machines. On the other hand, it is needed in the producing process

26、 at chemical factory, automobile factory, conveyer, automatic warehouse as automation.</p><p>　　3.4       Classification of control methods</p><p>　　Production meth

27、od by continuous process is employed, when scale of process industry gets bigger and larger production amount id requested.</p><p>　　You need to make proper use of the control method on some different condit

28、ion of operation. To classfy automatic control system is difficult strictly because their control system has correlation. But general method of cassification will be like below.</p><p>　　4-1 Classification

29、 by desired value</p><p>　　Automatic control Fixed command control</p><p>　　Following control Follow up control </p><p>　　Program control</p><p>　　4-1-1

30、 Fixed command control</p><p>　　Most of the controls belong to this control when desired value is constant.</p><p>　　4-1-2 Following command control</p><p>　　Servo mechanism compo

31、sed to follow the change belongs to this control when desired value changes optionally.</p><p>　　4-1-3 Program control</p><p>　　It is used for the control in which desired value changes accordi

32、ng to fixed time schedule. Normally , it is well used to temp. Control of fever process of metal or batch process at the chemical industry.</p><p>　　4-2. Classification by control method</p><p>

33、　　Automatic control Unity control loop</p><p>　　Ratio control </p><p>　　Cascade control</p><p>　　4-2-1 ratio control</p><p>　　It is well used to flow control of

34、2 fluid when desired value keeps with other fluid (other amount) constantly.</p><p>　　You compare and measure if special ratio keeps toward basic fluid (B), then maintain the ratio as the purpose.</p>

35、<p>　　4-2-2 Cascade control</p><p>　　It is the control method that more than 2 automatic control systems control by output of other control device. In short, control circuit is combined in series.</

36、p><p>　　You change the desired value of flow by output of flux adjuster. If you control the desired value of flow control to fix water level in water tank, then you can prevent the influence to the level such a

37、s main pressure change of flow itself.</p><p>　　The purpose of cascade control method is to absorb disturbance at first control, also to make easy the next step control, and to progress the control on the wh

38、ole.</p><p>　　3.5      Control action</p><p>　　At control action, movement to reduce control deviation, giving operating amount in accordance with a movement signal

39、 is called control action.</p><p>　　The following is this classification.</p><p>　　5-1 Continuous control</p><p>　　It does constantly correct movement toward deviation with desire

40、d value,measuring continuously toward controlled variable change.</p><p>　　5-1-1 Proportional action</p><p>　　It is the movement that operating amount Y is in proportion to movement signal and

41、deviation.</p><p>　　Suppose you make deviation as e, gain as kp,</p><p>　　3.6       Automatic control apparatus </p><p>　　Following apparatus are nece

42、ssary for each part, like a block diagram( See diagram 3-2) of feedback control. </p><p>　　◇ Primary Detecting element</p><p>　　◇ Final control element</p><p>　　◇ Controlling means&

43、lt;/p><p>　　6-1 Primary Detecting element</p><p>　　This is the part to take out necessary signals from controlling object , and transmit on control devece.</p><p>　　Expanding thermomet

44、er (Bimetal type)</p><p>　　Bimetal is the joined two metal boards which have different thermal expansion coefficient. It curves by temp.change.</p><p>　　Pressure type thermometer ( Vapor pressur

45、e )</p><p>　　You put vaporlizable liquied like propane or ether into thermal sensitivity part.</p><p>　　These liquid has certain vapor pressure, by contact surface with gas, and it deflects the

46、needle, by changing pressure measuring mechanism. </p><p>　　Resistance thermometer </p><p>　　It is well known that in thermometry resistor (Rt). Its resistance increases as electric resistance

47、 changes by temp. and temp. rises.</p><p>　　You build a bridge with thermometry resistor, and when its resistance value changes by temp., unbalanced current generates at the bridge. From this, you will know

48、the temperature. </p><p>　　(4)   Thermoelectric thermometer (Thermocouple)</p><p>　　Zeebesk effect is employed. You connect different kinds of metal. And make one connecting point temp

49、.(Thermometry contact point) higher than another connecting point (Standard contact point) . Then thermoelectromotive force is generated between both connecting points. </p><p>　　(5) Radiant thermometer &l

50、t;/p><p>　　Solid emits radiant energy in proportion to the square of four of absolute temp., like Stefan-Boltzmann’s formula.</p><p>　　(6) Thermocouple and thermometry resistor</p><p>

51、　　Detecting part (Temp.sensor) of temp.control experimental device (SPC-201) is mostly used in industrial tem.measurement.And it employs thermocouple and thermometry resistor with which you can measure in high accuracy a

52、nd easily. </p><p>　　6-2. Final control element ( Control valve)</p><p>　　Control valve receives output of adjuster and converts it into process variable Control valve is the element to feedbac

53、k to the process. So decides valve specifications. Understanding each controlled objects.</p><p>　　6-2-1 Control valve feature</p><p>　　(1) Flow feature( Proper feature)</p><p>　　Re

54、lation of lift of control valve. That is , valve operation signal, with flux is called flow feature,equal percentage feature and on-off feature represent.</p><p>　　near feature</p><p>　　queral

55、percentage feature</p><p>　　3、 On-off feature</p><p>　?、?#160;    Linear feature</p><p>　　Valve opening degree and flow are in proportion. Accordingly, flux changes 1

56、0% linearly,</p><p>　　as opening degree changes 10%.</p><p>　?、?#160;    Equal percentage feature</p><p>　　Flow increasing modulus becomes constant toward unit change

57、 of valve lift . Suppose there is flow increasing modulus at 10%, toward n% change of lift. Then flow will be.</p><p>　　When 10 L/min weighting is 10*0.1=1 L/min</p><p>　　When 50 L/min weighting

58、 is 50*0.1=1 L/min </p><p>　　When 90 L/min weighting is 90*0.1=1 L/min </p><p>　　Even if the same n% lift change, flow change is small, if flow is small. And it becomes big if flow is big. So, i

59、t has fine adjustment feature over wide flow range.</p><p>　?、?On-off feature</p><p>　　Flow soon reaches to the max.value, when a valve shift starts to move. It is usually used for 2-positionin

60、g control.</p><p>　　It is called on-off feature or quick open feature.</p><p>　　Relation of PID value and disturbance and control response toward setting change. Collect the relationship of P

61、ID value and control response toward disturbance, from experimental results, acquired at experiments.</p><p>　　proportional (P) action effect </p><p>　　????????????To increase proportional gain

62、</p><p>　　?To decrease off set amount (In case of no-integral action)</p><p>　　?To become oscillative ,and be hunting condition</p><p>　　?To get shouter the period of oscillation &l

63、t;/p><p>　　Integral (I) action results </p><p>　　Following things are conducted in a experiment ,changed only integral time TI and shortening TI.</p><p>　　?To lose off set amount</p

64、><p>　　?The first mountain gets smaller</p><p>　　?To become oscillative. Amplitude damping ratio gets bigger to finally exhale </p><p>　　?Returning time initially to setting value is s

65、hortened.</p><p>　　Differential (D) action effect </p><p>　　Following thing is conducted in a experiment ,changing only differential time and making TD longer.</p><p>　　?Off set amo

66、unt does not change (In case of no-integral action)</p><p>　　?The first mountain gets smaller</p><p>　　?Oscillation is restrained. Amplitude damping ratio gets smaller. But ,if differential time

67、 is too long ,it becomes oscillative again.</p><p>　　?Oscillaion period is shortened.</p><p>　　8. P.I.D adjustment procedure</p><p>　　You shall understand PID feature and nature fro

68、m experiments you did ,however, have difficulty in finding true value ,despite the adjustment .</p><p>　　Adjust P-I-D in order. Make step change toward desirable value, changing each constant. Then confirm a

69、nd record the results.</p><p>　　Change proportional (P) band from large number to small number. Stop it when measuring value causes hunting.</p><p>　　Change integral time (TI) from large number

70、to small number, too. Stop it when measuring value causes hunting, and bring a little back larger.</p><p>　　Change differential time (TD) from small number to large number. Stop it when measuring value cause

71、s hunting, and bring a little back smaller.</p><p>　　When you wish to shorten setting time, make P much smaller, and check the change of measuring value.</p><p>　　9. Optimum adjustment</p>

72、<p>　　To arrange the control purpose based on the former experiments.</p><p>　　When you change desirable value, make measuring value and desirable value agree, as soon as possible. (Desirable value ch

73、ange, step response)</p><p>　　If measuring value deviates from desirable value, owing to changes of surrounded condition temporarily, put it back as soon as possible. (Disturbance response)</p><p&

74、gt;　　As for (1) , time passage to make them agree is the problem. Measuring value change on PID value, in case of desirable value change, will be normally like diagram 9-1.</p><p>　　At this diagram, temporar

75、ily it gets over desirable value. This is called overshoot. To decrease this over amount, and to shorted time to settle down measuring value (Setting time) do not normally coexist. In short, adjusting not to get over mak

76、es the setting time longer.</p><p>　　Also, control process may have some trouble, if you shorten the setting time, ignoring over amount. On the other hand, it may be better to reach the desirable value soone

77、r in spite of over amount. So, establishing guideline of overshoot, and you have and adjusting method, making time minimum within the range. It is called optimum adjustment, to adjust PID constant.</p><p>&l

78、t;b>　　自動控制基礎(chǔ)</b></p><p><b>　　提綱</b></p><p>　　這套設(shè)備是用來測量溫度、流量、液位、壓力的實驗設(shè)備中的溫度的設(shè)備。溫度、流量、液位、壓力這些控制量是水處理廠、化工廠、電廠中最普遍的控制對象。在這些自動控制實驗中，最重要的是保持系統(tǒng)平衡。</p><p>　　自動控制系統(tǒng)是由控制對

79、象、控制裝置組成的。尤其是過程控制，它要求有多種控制對象來保持自身平衡。因此，實驗結(jié)果是在平衡的情況下得到的。在串級實驗和固定命令控制下，這套實驗裝置通過測試輸入與輸出的關(guān)系來保持系統(tǒng)的平衡。因此，這套系統(tǒng)有靜態(tài)特性和動態(tài)特性。</p><p>　　這個反映是階躍響應(yīng)的結(jié)果。</p><p><b>　　過程控制</b></p><p>　　過

80、程控制是保持系統(tǒng)的平衡，自動調(diào)整偏差。根據(jù)工業(yè)過程中液面、壓力、流量、溫、等要求的目標(biāo)來比較，自動調(diào)節(jié)偏差。</p><p>　　過程控制分為開環(huán)控制和閉環(huán)控制。</p><p>　　3、 自動控制的種類</p><p>　　控制是由檢測裝、比較裝置、調(diào)節(jié)裝置、執(zhí)行裝置組成并且手動控制是由人通過手工實現(xiàn)的，自動控制是通過機械、調(diào)節(jié)器、檢測器實現(xiàn)的。在目前，自動被用于

81、許多工廠中，甚至，我們無法想象，在工廠中沒有過程控制會怎樣。</p><p>　　各種過程控制的分類如下所示：</p><p><b>　　3-1反饋控制</b></p><p>　　自動控制 開環(huán)控制 前饋控制</p><p><b&

82、gt;　　順序控制</b></p><p>　　閉環(huán)控制 反饋控制</p><p>　　反饋控制主要依據(jù)比較部分來實現(xiàn)自動操作。它返回的每部分的測量結(jié)果，如果測量值與給定值產(chǎn)生偏差，那么根據(jù)二者之差將操作值也作相應(yīng)的調(diào)整。</p><p>　　反饋控制是一種主要的過程控制，我們將以如圖3-1的液位控制系統(tǒng)為例進(jìn)行介紹。</

83、p><p>　　這個控制系統(tǒng)檢測結(jié)果（被控參數(shù)：水塔的液位）被測量變送器轉(zhuǎn)化之后，與設(shè)定液位進(jìn)行比較，然后根據(jù)比較結(jié)果閥的開度，直至最后使液位達(dá)到平衡。</p><p><b>　　3-2、前饋控制</b></p><p>　　前饋控制特點：按干擾作用的大小進(jìn)行控制，可以克服擾動或給定突然改變帶來的問題，一般比反饋控制要及時，但一種前饋控制只能克服

84、一種干擾；反饋控制屬于閉環(huán)而前饋控制屬于開環(huán)控制，且其使用的是視對象特性而定的特殊控制器。</p><p>　　一般前饋控制很難達(dá)到控制要求，因為對實際系統(tǒng)來說將所有的擾動區(qū)分開來去建立一個實際模型是不可能的。因此，前饋控制通常與反饋控制、串級控制共同使用以達(dá)到良好的控制效果。</p><p><b>　　3-3、順序控制</b></p><p&g

85、t;　　順序控制適用于高級單步執(zhí)行系統(tǒng)。這種順序控制常用在霓虹燈廣告牌，全自動洗衣機或電動洗衣機等領(lǐng)域，另一方面，化工廠、汽車廠、轉(zhuǎn)化器、自動倉庫的生產(chǎn)過程中也經(jīng)常使用順序控制器。</p><p><b>　　4、控制方法的分類</b></p><p>　　實際和產(chǎn)經(jīng)常使用連續(xù)的生產(chǎn)方式，而生產(chǎn)過程中很少有要求太大的被控量。</p><p>　

86、　4-1 根據(jù)給定值分類</p><p>　　自動控制： 定值控制</p><p><b>　　隨動控制：隨動控制</b></p><p><b>　　程序控制</b></p><p>　　4-1-1 恒值控制</p><p>　　實際生產(chǎn)中，大多數(shù)的控制都屬于給定值為常數(shù)的

87、恒值控制。</p><p>　　4-1-2 隨動控制</p><p>　　隨動控制是輸出隨給定變化的控制。</p><p>　　4-1-3 程序控制</p><p>　　它是給定值按固定的程序設(shè)定時間而變化，通常被用在化工生產(chǎn)中溫度的過程化控制。</p><p>　　4-2 根據(jù)控制方法分類</p>&l

88、t;p>　　自動控制：單元控制、 比值控制、 串級控制</p><p>　　4-2-1 比值控制</p><p>　　實現(xiàn)兩個或兩個以上參數(shù)符合一定比例關(guān)系的控制系統(tǒng)，通常以保持兩種或幾種物料的流量為一定比例關(guān)系的系統(tǒng)。</p><p>　　經(jīng)過比較、測量確定兩種物料中處于主導(dǎo)地位物料便于實現(xiàn)比值控制。</p><p><b>

89、;　　6、自動控制部分</b></p><p>　　下面將要介紹各個部分對于反饋控制是必不可少的。</p><p>　　基本檢測單元、執(zhí)行單元、 控制單元</p><p><b>　　6-1基本檢測要素</b></p><p>　　在控制設(shè)備中，這是從被控對象上提取重要的信號的部分。用壓力檢測的基本要素如下：

90、</p><p>　　6-1-1 流量檢測</p><p>　　我們通常辨別物質(zhì)為三種狀態(tài)：固體、液體、氣體。固體的形狀是固定的，幾乎不能改變。液體是容易改變形狀和體積的。在三種物態(tài)中，液體和氣體被通稱為流體。</p><p>　　單位時間里通過一定區(qū)域的流動流體的體積或質(zhì)量稱為流量。測量流量有以下幾</p><p>　　種方法：（１）差壓

91、式流量計</p><p>　　將一個節(jié)流裝置即帶孔的金屬盤放在流體流過的管子中，流體在通過盤前后是產(chǎn)生不同的壓力。流體通過節(jié)流裝置時，節(jié)流裝置的上游、下游之間產(chǎn)生壓差。這個壓差與流量有關(guān)，所以我們就可以通過測量這個壓力差得到流量。</p><p><b>　?。ǎ玻┺D(zhuǎn)子流量計</b></p><p>　　將浮子放入一個錐形管子中，被測流體由底部

92、向上漲，引起浮子上移。浮子上移的數(shù)量與流量有關(guān)，這個值隨流量改變。</p><p><b>　　（３）電磁流量計</b></p><p>　　在磁感應(yīng)強度均勻的磁場中，垂直于磁場方向放置一個不導(dǎo)磁的管道，在該管道上與磁場垂直方向設(shè)置一對同被測介質(zhì)相接觸的電極，管道與電極之間絕緣。當(dāng)導(dǎo)電流體流過管道時，相當(dāng)于一根長度為管道內(nèi)徑Ｄ的導(dǎo)線在切割磁力線，因而產(chǎn)生了感應(yīng)電勢，并

93、由兩個電極引出。感應(yīng)電勢與被測介質(zhì)的流量成線性關(guān)系。</p><p><b>　?。ǎ矗┏暡髁坑?lt;/b></p><p>　　超聲波在流體中的傳播速度與流體的平均流量有關(guān)?？梢酝ㄟ^測量傳播速度、管長、流體流動的速度來確定流量。 （５）動態(tài)壓力流量計</p><p>　　裝在管子中心的元件獲得的功率與流量的２倍成正例。因此當(dāng)功率傳送到

94、上面的傳感器時，就可以知道流量的大小。</p><p>　?。ǎ叮E圓齒輪流量計</p><p>　　當(dāng)流體有下向上流過，由于壓力損失，使出口和入口產(chǎn)生壓差，橢圓齒輪在此壓差作用下產(chǎn)生力矩而轉(zhuǎn)動。當(dāng)橢圓齒輪與殼間的半月牙容積Ｖ一定時，只要測出橢圓齒輪的轉(zhuǎn)速Ｎ，便可知被測流體的體積流量Ｑ，即</p><p><b>　　Ｑ＝４ＮＶ</b><

95、/p><p><b>　　（7）水壩式流量計</b></p><p>　　在水流的方向上建以個水壩，讓水流流過壩，使水流增大，水位升高。這就固定了流量與壩形狀的關(guān)系?？梢酝ㄟ^壩的表面和高度知道流量。</p><p>　　直角三角壩： Q=Kh5/2(m/h)</p><p>　　方型壩：

96、Q=Kbh3/2(m/h)</p><p>　　一般壩： Q=Kbh3/2(m/h)</p><p>　　6-1-2電磁流量計的使用原理</p><p>　　電磁流量計用于流量控制實驗設(shè)備（SPC-315）中測量流量。</p><p>　　電磁流量計的原理是根據(jù)法拉弟定律當(dāng)流體在磁場中流動時產(chǎn)生的感應(yīng)電動勢與流速成正比。

97、產(chǎn)生的感應(yīng)電勢是垂直于電磁場方向和液體流動方向，可通過右手定則判斷。電磁流量計將產(chǎn)生的感應(yīng)電動勢轉(zhuǎn)換成4-20mA的統(tǒng)一標(biāo)準(zhǔn)直流電信號。</p><p>　　感應(yīng)電動勢E的大小用下式表示：</p><p>　　E=D·V·B (1)</p><p><b>　　E：表示感應(yīng)電

98、勢</b></p><p><b>　　B：磁感應(yīng)強度</b></p><p><b>　　D：管道內(nèi)徑</b></p><p><b>　　V：流體的平均流速</b></p><p>　　流量表示為Q[M/S]</p><p>　　Q=

99、 （2）</p><p>　　所以感應(yīng)電勢E被表示為 E= （3）</p><p>　　從式（3）中可知，感應(yīng)電勢E是和流量Q成正比的。</p><p>　　電磁流量計的正確使用條件：</p><p>　　1. 被測介質(zhì)具有導(dǎo)電性；&l

100、t;/p><p>　　2. 測量管道內(nèi)充滿液體；</p><p>　　3. 液體是單一物質(zhì)；</p><p>　　4. 流體是無磁性的。</p><p>　　6-2 執(zhí)行單元（控制閥）</p><p>　　控制閥是過程控制系統(tǒng)的一個重要組成部分，其接受過程反饋數(shù)據(jù)的調(diào)節(jié)并將其轉(zhuǎn)換后對過程進(jìn)行控制。因此，閥的特性對控制質(zhì)量

101、至管重要。</p><p>　　6-2-1控制閥特性</p><p><b>　　理想的流量特性</b></p><p>　　控制閥的流量特性是指閥的操作信號與流量之間的關(guān)系?？煞譃橹本€特性，等百分比特性和開關(guān)特性。</p><p>　　直線特性、百分比特性、開關(guān)特性</p><p><b&

102、gt;　?、僦本€特性</b></p><p>　　閥的開度與流量成比例關(guān)系。即閥的開度改變10%，其流量也改變10%。</p><p><b>　?、诘劝俜直忍匦?lt;/b></p><p>　　閥桿的單位相對位移（開度）變化所引起的相對流量變化與該點的相對流量成正比。例如，</p><p>　　量增加率為10%

103、，閥的開度將變化n%。</p><p>　　當(dāng)開度為10%，其流量變化為 10×0.1=1L/min</p><p>　　當(dāng)開度為 50%，其流量變化為 50 ×0.1=5L/min</p><p>　　當(dāng)開度為90%，其流量變化為 90 ×0.1=9L/min</p><p>　　即使同樣是n%

104、的開度，流量的變化也很小。所以利用等百分比流量特性是有利的，控制閥在小開度時，控制作用緩和平穩(wěn)，控制閥在大開度是，控制及時有效。</p><p><b>　?、劭扉_特性</b></p><p>　　當(dāng)閥開始移動時，流量很快到達(dá)最大值。它通常用在二位控制系統(tǒng)中。它被稱</p><p>　　為開關(guān)特性又叫快開特性。</p><p

105、>　　1、研究PID的值與系統(tǒng)抗擾能力及系統(tǒng)對突加給定的響應(yīng)的關(guān)系。</p><p>　　通過實驗的數(shù)據(jù)找出PID參數(shù)與擾動響應(yīng)的關(guān)系。</p><p><b>　　比例環(huán)節(jié)的作用</b></p><p><b>　　·增大比例系數(shù)</b></p><p>　　·發(fā)生波動，

106、搜索狀況</p><p><b>　　·減少調(diào)節(jié)時間</b></p><p><b>　　微分環(huán)節(jié)作用</b></p><p>　　通過實驗只改變微分時間TD，使TD變大，可以得到以下結(jié)論</p><p>　　·系統(tǒng)有靜差（在無積分作用時）</p><p>

107、;　　·第一個峰值變小超調(diào)量減小</p><p>　　·波動穩(wěn)定，振幅斜率變小，但如微分時間太長，波形將再次振蕩</p><p><b>　　·調(diào)節(jié)時間變小</b></p><p><b>　　積分環(huán)節(jié)作用</b></p><p>　　通過實驗只改變積分時間TI，使TI

108、變大，可以得到以下結(jié)論。</p><p><b>　　·系統(tǒng)無靜差</b></p><p>　　·第一個峰值的高度變?。ǔ{(diào)量變小）</p><p>　　·產(chǎn)生波動，而振幅傾斜變大直至發(fā)散</p><p>　　·系統(tǒng)回復(fù)到設(shè)定值的時間變短</p><p>&

109、lt;b>　　2、PID調(diào)節(jié)過程</b></p><p>　　通過進(jìn)行實驗理解PID的作用和特性，然而很難找到最佳調(diào)節(jié)作用的值。</p><p>　　以下過程中找到最佳的PID 值的方法：</p><p>　?。?）P-I-D在順序逐個改變參數(shù)，使響應(yīng)接近理想的值，確定并記錄結(jié)果。</p><p>　　（2）從大到小改變比例

110、放大系數(shù)，當(dāng)測量值產(chǎn)生搜索時，停止改變。</p><p>　　（3）從大到小改變積分時間，當(dāng)測量值產(chǎn)生搜索時，將積分時間變大一點。 </p><p>　?。?）從小到大改變微分時間，當(dāng)測量值產(chǎn)生搜索時，停止改變微分時間，并將微分時間再調(diào)小一點。</p><p>　?。?）當(dāng)希望減小調(diào)節(jié)時間時，把比例系數(shù)調(diào)小一點，再檢查測量值的變化。</p><p

111、><b>　　最優(yōu)控制</b></p><p>　　根據(jù)前面的實驗，安排設(shè)置控制目標(biāo)。</p><p>　　希望在改變設(shè)定值時，使測量值盡可能快的與設(shè)定值相同（同步跟隨測</p><p><b>　　量值的變化）。</b></p><p>　　假如由于周圍環(huán)境的臨時改變而導(dǎo)致測量值偏離給定，則

112、希望盡可能地</p><p>　　使測試值返回到給定值。（擾動響應(yīng)）</p><p>　　對于第一種情況，調(diào)節(jié)時間是關(guān)鍵問題。在給定值發(fā)生變化時，測量值在PID調(diào)節(jié)作用下改變，一般變化過程如圖（9-1），在此圖中測量值暫時超過了給定值，這被稱為超調(diào)量。減少超調(diào)量和縮短調(diào)節(jié)時間通常不能同時滿足。簡而言之就是調(diào)節(jié)沒有超調(diào)就會使調(diào)節(jié)時間變長。同理，在過程控制中也會遇到同樣的問題。如果減少時間，超