外文翻譯-液位控制系統(tǒng)

1、畢業(yè)設(shè)計(jì)論文英文翻譯系 別專 業(yè)班 級(jí)學(xué)生姓名學(xué) 號(hào)指導(dǎo)教師報(bào)告日期International Railway JournalLevel Control System【Title】 International Railway Journal【Publication Date 】2021【No.】 period MarchIon Matei, Dumitru Popescu, Ciprian Lupu, llie LuicanPolitehnica University of Bucharest - Control and Computer Science FacultySplaiul Inde

2、pendentei nr.313,sector6,Bucurcsti,Romaniaemail: inion 3 home .ro1 Level control systemThe fluid flow is controlled by an electric pomp. The process input is a voltage with values between 0 and 10 V and the output is the fluid level measured by an ultrasounds transducer. The process is nonlinear but

3、 it is approximated with linear mathematical model around a representative point of functioning. The approximated mathematical model which was obtained using the sample period Te = 5s. It is important to mention that for designing a numerical regulator three steps must be followed:- computing the di

4、screte model;- performances specification;- computing the adequate control algorithmIn this case for the level control were used the next numerical control algorithms: RST and PID with its two variants, PIDl and PID2. These algorithms have different performances so that the students will have the op

5、portunity to compare them. First it will be presented the RST algorithm and than the paper will continue with PID algorithms which will be structured analyzed and compared to the first one.2 PID algorithmNumerical PID algorithm comes from sampling the continuous PID algorithm with all appropriate sa

6、mpling period.Numerical PID controllers are suitable only for processes modeled by a second order transfer function with or without pure delay.It is worth to mention that some numerical PID controllers do not have a continuous equivalent.2.1 PIDl numerical algorithmLet us consider the algorithm:The

7、transfer functions of a continuous PID controller，This algorithm is specified by four parameters:K - proportional action;Ti - integral action;Td - derivative action;Td - filtered derivative action.There are many methods that can be used to sample this algorithm resulting in a numerical controller of

8、 the same form.As it may be seen, PIDl numerical regulator has also four parameters (rth r1 r2, s1) as its continuous form. This algorithm can be International Railway Journalstructured in a RST form if T(q-1)=R(q-1 ).It is easy to notice that PIDl is one freedom degree algorithm. The transfer funct

9、ion in closed loop which join the reference r(t) with the output y(i) is, where P(q-1)defines the poles wanted in closed loop that determine the performances for perturbations rejection. PIDl algorithm introduces new zeros in closed loop by polynomial R(q-1) that alter the performances. This negativ

10、e effect will be partially eliminated by thePID2 algorithm. Having already determined the RST algorithms it is now easy to calculate the PIDl parameters (if the rejection performances define by P (q-1) are not changed) because the polynomials R(q-1) and S(q-1) will be the same 3.As it may be observe

11、d in the next graphics the perforinanccs of the PIDl algorithm are inferior to the RST algorithm.2.2 PID2 numerical algorithmAs it was noticed above the PIDl regulator introduces supplementary zeros in closed loop by polynomial T(q-1)=R(q-1). Those zeros affect specially the control performances as

12、it was observed in figure 7. This disadvantage can be partially eliminated if the polynomial T(q-1) is chosen. assuring in this manner a unitary transfer function in stationary regime 3.The block schematics of the PID2 numerical algorithm structured as RST is presented bellow.This algorithm assures

13、superior performances compare to PIDl as it may be seen in the next graphics.3 RST numerical algorithmFor any control system there are defined two important objectives:1 . Reference 's tracking;2 . Rejection of the perturbations;A classical control structure. with only one liberty degree (fig. 2

14、) has the great disadvantage that it can not fulfill the two objective defined above.As it may be noticed the command is not pondered differentially by reference and measure. This means that some performances defined for perturbations rejection could restrict the reference tracking. If the polynomia

15、l R(q-1), which filter the reference, is replaced by another polynomial T(q-1) i t will lead to a RST structure with two liberty degree that accepts different performances in tracking and rejection3 4.The block structure of the RST numerical algorithm is presented in the next figure:The closed loop

16、transfer function is:The performances for rejection are established by characteristic polynomial P(q-1) obtained by sampling a second order continuous system. The polynomials R(q-1) and S(q-1) results from solving the next polynomial equation:A(q-1)S(q-1)+ q-dB(q-1)R(q-1)= P(q-1) (4)The tracking per

17、formances are controlled by T(q-1) and reference filtering. The polynomial T(q-1) is chosen so that the close loop International Railway Journaltransfer is unitary (the output will follow the imposed reference y*).T(q-1)=P(q-1) (5)Tracking dynamics can be modify by polynomials Bm(q-1) and Am(q-1) wh

18、ich filter the reference:Polynomials Bm, and Am, result also from sampling a second order continuous system. Therefore choosing the parameters and will determine the tracking performances 4.The block diagram of the RST control structure with filtered reference is presented below:The system tracking

19、performances are chosen by a second order system with ,I = 0.25, = 0.99 which results in:The rejection performances are also given by a second order system with: n= 2.5, = 0.8.The characteristic polynomial for the poles allocation method, will become:P(q-1)=1 - -1 + -2 (8)Solving the system (4) and

20、applying (5) results in:R(q-1)=-1 -2 (9)S(q-1) = 1 - 1q-1 + 1q-2 (10)T(q-1)=6.3423 -1 +-2 (11)System response to step and perturbations rejection are presented in the figure below:4 Virtual experimentThe experiment presented in this paper is a part of the laboratory activity of “Identification and C

21、ontrol Systems, course dedicated to the forth year students from the UPB-Control and Computer Science Faculty. The laboratory purpose is to train students in practical activity of system identification and numerical process control. During this part of the practical activity the students have the po

22、ssibility to control the level fluid from a tank by testing different type of numerical algorithms. In the figure IO is presented an image of the level control didactical platform. The lab activity. in the virtual version proposed.is structures in two parts. In the first part students practice the o

23、pen loop identification of the studied process, the presence of the students in the laboratory being necessary. The second part of the lab consists in numeric control of the identified process by testing various algorithms. For this section of the lab the prescnce of the students in the laboratory i

24、s not compulsory because the activity could be undertaken from any place with an internet connection. The virtual experment is formed from two components: a hardware and o software structure.4.1 Hardware structureThe base of this experiment is a hardware structure composed from:- an acquisition boar

25、d with analog to digital and digital to analog converters which acquires and send data to the process;- a PC compatible IBM with a Pentium II 350 MHz processor and 64 Mbytes RAM, which contain the acquisition board;- a video camera for real-time images broadcasting;International Railway Journal- a H

26、P LH3 server for Internet connection4.2 Software structureThe software structure is formed by to subsystems which allow access to the didactical platform local as well as distant - using the Internet as it may be observe in figure 10: The first subsystem represents a program written in Lab Windows/C

27、VI. It runs on the computer connected to the process and allows direct local access to the platform. This application represents a gate for the data that leave and come to the process.The second subsystem is a client-server application which assures distant interaction with the process.4. Local acce

28、ssThe program for local access was created using Lab Windows/CVI and it is an independent application that allows local access to the platform independent towards the distant access.This program makes the connection with the process acquiring and sending data from respectively to the process. The da

29、ta is sent further on to thc clients applications via the Internet.The local application assures a fcw operations over the platform such as:- reference changing;- automat/manual regime changing;- manual command;- algorithms configuration.For an easy use, the local program has a graphical user interf

30、ace (GUI) presented bellow.4.2.2 Distance accessThe base of the distant communication is a clientserver application. There are some key words that define such an architecture which will be described as follows:Server - entity that accepts requests and offers services to the clients connected to him

31、5. For this experiment the server is a program written in Java which runs on HP LH3 server machine. The server connects itself to the local application and become a proxy for the clients that connect to him. The server is a multithreading program that runs in background and sends periodically data a

32、bout the state of the process to the clients. Theoretically it can accept an infinite number of client connections but the number is limited by software to maintain a certain level of performances.Client - software entity which sends requests to the server and process the data received as answer 5.

33、For this experiment the client is a Java applet incorporated in a web page. Next to the applet there arc presented live images with the process evolution.International Railway Journal5. ConclusionsIn this paper a level control system with distant access option that allows monitoring and updating of

34、important parameters of the system is presented. There are presented the base theory for level control and the hardware and software structures for distant access via the Internet.A comparative study for performance evolution of different control algorithms can be realized.The system has been create

35、d as an educational tool through the students can experiment distant access to a technological platform. 國際鐵路雜志液位控制系統(tǒng)【標(biāo)題】國際鐵路雜志【出版日期】 2021【編號(hào)】三月期離子馬太，杜米特魯·波佩斯庫，西普里安盧浦， llie Luican控制與計(jì)算機(jī)科學(xué)系 - 布加勒斯特Politehnica大學(xué)Splaiul Independentei nr.313 ， sector6 ， Bucurcsti ，羅馬尼亞電子郵件： INION 3家RO1液位控制系統(tǒng)所述流體流是由

36、一個(gè)電控的盛況。該過程的輸入是用介于0和10 V值的電壓輸出是由一個(gè)超聲波換能器測(cè)量的流體的水平。該過程是非線性的，但它是近似與周圍的代表點(diǎn)功能的線性數(shù)學(xué)模型。這是利用樣本時(shí)間段Te = 5秒得到的近似數(shù)學(xué)模型。重要的是要提的是設(shè)計(jì)一個(gè)數(shù)字調(diào)節(jié)器必須遵循三個(gè)步驟是很重要的：- 計(jì)算離散模型;- 性能標(biāo)準(zhǔn);- 計(jì)算適當(dāng)?shù)目刂扑惴ㄔ谶@種情況下為電平控制被用來在未來的數(shù)字控制算法： RST和PID與它的兩個(gè)變種， PIDL和PID2 。這些算法有不同的表演，讓學(xué)生們將有時(shí)機(jī)對(duì)它們進(jìn)行比擬。首先，將介紹在RST算法和比紙張將繼續(xù)與將在結(jié)構(gòu)化分析和比擬，以第一個(gè)PID運(yùn)算。2 PID算法數(shù)字PID算法來

37、自與所有適當(dāng)?shù)牟蓸又芷诓蓸拥倪B續(xù)PID算法。數(shù)字PID控制器只適合用帶或不帶純滯后二階傳遞函數(shù)建模的流程。值得一提的是一些數(shù)字PID控制器不具有持續(xù)等效。2.1 PIDL數(shù)值算法讓我們考慮的算法：連續(xù)PID控制器的傳遞函數(shù)，該算法被指定由四個(gè)參數(shù)：的K - 比例作用;TI - 積分作用;TD - 微分作用;TD - 過濾派生訴訟。有許多方法可以用來采樣這個(gè)算法產(chǎn)生的以相同的形式的數(shù)字控制器。由于可以看出， PIDL數(shù)字調(diào)節(jié)器還具有四個(gè)參數(shù) RTH R1 R2 ， S1作為它的連續(xù)形式。該算法可以是國際鐵路雜志結(jié)構(gòu)采用了第一種形式，如果T Q- 1 = R Q- 1 。這是很容易看到， PIDL

38、是自由度算法。在閉環(huán)其中參加參考RT 與輸出y i該傳遞函數(shù)，其中，P Q- 1限定的極點(diǎn)在閉環(huán)需求確實(shí)定的性能對(duì)擾動(dòng)抑制。 PIDL算法由多項(xiàng)式R Q-1 ，該改變的性能引入閉環(huán)新的零。這種負(fù)面影響將被局部地消除PID2算法。在已經(jīng)確定的RST的算法現(xiàn)在是很容易計(jì)算的PIDL參數(shù)如果拒絕表演定義為P Q-1不改變，因?yàn)槎囗?xiàng)式R Q-1 和S Q-1將相同的3。因?yàn)樗赡軙?huì)在未來的圖形應(yīng)遵守的PIDL算法的perforinanccs處于劣勢(shì)的RST算法。2.2 PID2數(shù)值算法因?yàn)樗厦娴腜IDL調(diào)節(jié)注意到引入閉環(huán)補(bǔ)充零多項(xiàng)式T Q-1 = R Q -1。那些零影響專門的控制性能，因?yàn)樗怯^察

39、到的圖7中。這個(gè)缺點(diǎn)可以被局部地消除，如果多項(xiàng)式T Q-1 被選擇。以這種方式保證在固定的制度一整體的傳遞函數(shù)3。結(jié)構(gòu)為RST的PID2數(shù)值算法的結(jié)構(gòu)原理圖呈現(xiàn)波紋管。該算法保證了優(yōu)異的性能比擬PIDL ，因?yàn)樗赡軙?huì)在未來的圖形可以看出。3 RST數(shù)值算法對(duì)于任何控制系統(tǒng)中定義了兩個(gè)重要目標(biāo)：1 。參考的跟蹤;2 。擾動(dòng)的抑制;一個(gè)經(jīng)典的控制結(jié)構(gòu)。只有一個(gè)自由程度圖2具有很大的缺點(diǎn)，即它不能滿足這兩個(gè)目標(biāo)定義如上。因?yàn)樗赡軙?huì)注意到命令不被參考和測(cè)量差分思考。這意味著，對(duì)于擾動(dòng)抑制定義了一些演出可能限制基準(zhǔn)的跟蹤。如果多項(xiàng)式R Q- 1 ，其中過濾器的引用，被替換為另一個(gè)多項(xiàng)式T Q- 1

40、，它會(huì)導(dǎo)致一個(gè)RST結(jié)構(gòu)與接受的跟蹤和排斥不同場(chǎng)次2自由程度 3 4 。在RST數(shù)值算法的塊結(jié)構(gòu)呈現(xiàn)下列圖：的閉環(huán)傳遞函數(shù)是：表演拒絕通過由采樣二階連續(xù)系統(tǒng)獲得的特征多項(xiàng)式P Q-1成立。多項(xiàng)式R Q-1 和S Q-1從解決下一多項(xiàng)式方程的結(jié)果：A Q-1 S Q-1 + Q -dB的第q- 1R Q-1 = P Q-1 4的跟蹤性能進(jìn)行由T Q-1和參考濾波的控制。多項(xiàng)式T Q- 1 的選擇，使閉環(huán)國際鐵路雜志轉(zhuǎn)移是酉輸出將按照規(guī)定的參考Y * 。T Q-1 = P Q-1 5跟蹤動(dòng)力學(xué)可以通過多項(xiàng)式進(jìn)行修改Bm的第q- 1和Am Q-1該過濾器的參考：多項(xiàng)式BM和AM，從采樣二階連續(xù)系統(tǒng)也造成。因此選擇的參數(shù)和將確定的跟蹤性能4。在RST控制結(jié)構(gòu)與過濾引用的方框圖列示如下：該系統(tǒng)的跟蹤性能是由一個(gè)二階系統(tǒng)選擇， I = 0.25 ， = 0.99結(jié)果為：拒絕演出是由一個(gè)二階系統(tǒng)還給出為：n = 2.5 ， = 0.8 。為兩極分配方法的特征多項(xiàng)式，將成為：P Q-1 = 1 - 1.2807q -1 + 0.4493q - 28求解系統(tǒng)4和應(yīng)用5的結(jié)果如下：R Q-1 = 5.1232 - 6.5q -1 + 2.0516q - 29S Q-1 = 1 - 11.432q -1 + 0.4321q - 210