Real-Time Computer Level Control of a Water Tank.docx

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1、Academic Year: (2012/2013)Enrolment number: 12014664Full name: Sijun WuCourse: BEng Honors Degree in Electrical andElectronic EngineeringProject Title: Real-Time Computer Level Control of a Water Tank1st Supervisor: Guoping Liu2nd Supervisor: Dr Mike PriceDate: April 2013Real-Time Computer Level Con

2、trol of a Water TankStudent: Sijun WuID: 12014664Date: April 2013University of GlamorganDissertation submitted in partial fulfillment for the BEng in Electrical and Electronic Engineering.Faculty of Advanced TechnologyDeclarationI understand the nature of plagiarism, and I am aware of the University

3、s policy on this.I declare that this dissertation is the result of my own independent investigation and that all sources have been appropriately acknowledged in the bibliography.Signature: Date:AbstractWith the development of the times, Control system is playing an increasingly important role in var

4、ious fields. Water tank control system is a typical model of control system. Control of water tank can be used as the basis of research into more complex nonlinear system, It not only has a strong theoretical, belongs to the application of basic research, but also it with strong comprehensive. It co

5、ntains control theory, intelligent control, fluid mechanics, and other disciplines. Peoples life and industrial production, and many other areas often involve liquid level and flow control problem, for example in Inhabitant domestic water supply, beverages, food processing and other industries the p

6、roduction process, we usually need to use the water tank, it need to maintain the appropriate level, neither too overflow cause waste, also cannot too little and cant meet the demand. So the liquid height is an important parameter of the industrial process control, especially in a dynamic state. By

7、using suitable methods to detect the liquid level can control it can receive good effect.In this final project design, I duty is to design a water tank liquid level control system, which involves the dynamic liquid level control, the modeling of the control system, PID parameters setting. I will dis

8、cuss using different control methods to achieve control require, for instance, Proportional controller, PI controller. I will discuss both design processes and test results in this paper. What more I will introduce some main software which includes MATLAB, SIMULINK, and NetCon Systems.Key words: pos

9、ition control, PI controller, PID parameters setting, software AcknowledgementFirst of all, I want appreciate my first supervisor and second supervisor. I could not achieve my project without their help. Especially professor Guoping Liu, he gives me great support. When some questions really confuse

10、me, he always fills of patient and answer for me. He encourages me and teaches me how to solve the problems. He not only teaches me knowledge but also creative my ability of research the essential of the problem. No matter in the theoretical knowledge and practical test.Secondly I want to appreciate

11、 the University of Glamorgan. They give me opportunity to learn the theory with the real application. Thirdly I want to say thanks to Beijing University of Civil Engineering and Architecture where I used to study. They gave me the chance to study in the University of Glamorgan now. I want to appreci

12、ate my teacher in china, especially professor Zhijian Jiang. At last I want to say thank to any people who support me. Especially thanks to my parents and my friends. All of you are very important for me and I really appreciate the help that you gave me in this whole year.contentAbstract4Acknowledge

13、ment5content6Figure list9Chapter1. Project Overview111.1Aim and Objectives:111.2 General Background:111.2.1 Single water-tank system111.2.2 Couple water-tank system12Chapter2. Software Introduction142.1 MATLAB Introduction142.2 Simulink introduction162.3 NetCon System172.3.2NetConLink182.3.3 NetConT

14、op19Chapter3. Hardware Introduction203.1 Coupled-tank system description203.2 Component nomenclature213.3 component description223.3.1 Overall frame and water tanks223.3.2 Pump223.3.3 Pressure sensor223.4 Coupled-tank model parameters22Chapter4. Theory and mathematical model254.1 Mathematical model2

15、54.2Mathematical model of the upper water tank254.2.1 Upper water tank level modeling nonlinear equation of motion254.2.2 Upper water tank level modeling linearization and system transfer function284.3Mathematical model of the couple water tank314.3.1 Couple water tank level modeling nonlinear equat

16、ion of motion314.3.2 Couple water tank level modeling linearization and system transfer function33Chapter5. Introduction of control systems and Controller Design375.1Introduction of control systems375.2 Upper water tank water level controller design385.2.1 Upper water tank water level P-plus-feedfor

17、ward controller385.2.2 Upper water tank water level PI-plus-feedforward controller425.2.3 Upper water tank water level Cascade and feedback controller465.3 Couple water tank water level controller design485.3.1 The Instructions for the cascade system.485.3.2 Couple water tank water level PI-plus-fee

18、dforward controller49Chapter6. The simulation of the system controller526.1 The simulation of upper water controller526.1.1 Simulation of Proportional controller526.1.2 Simulation of proportional integral controller546.1.3 Simulation of cascade and feedback controller556.2 The simulation of couple w

19、ater tank controller57Chapter7. Actual experimental operation and test results617.1 The Instructions for actual experimental617.1.1 The Instructions for the digital to analog and analog to digital conversion617.1.2 The Instructions for using NetConSystem NetConLink and NetConTop627.1.3 Water level s

20、ensor calibration647.14 look-up table657.1.5 Limit voltage protection system667.2 Experimental results and analysis of the upper water tank677.2.1 Experimental results of P-plus-feedforward controller677.2.2 Experimental results of PI-plus-feedforward controller697.2.3 Experimental results of cascad

21、e and feedback controller717.3 Experimental results and analysis of the couple water tank73Chapter8. Mistake analysis76Chapter9. Conclusions77Chapter10. Future Work78Reference79Appendix 180Appendix 297Figure listFigure1. Illustrating the AnalogyFigure2. Schematic of the Coupled-Tank plantFigure3 The

22、 overall NetCon systemFigure4 NetControllerFigure5 Interface of NetConLinkFigure6 User Interface of NetConTop softwareFigure7 Coupled-tank ModelFigure8 Coupled-tank ComponentFigure 9 Upper water tank level modelFigure 10 The open-loop transfer function of the upper water tankFigure 11 couple water t

23、ank level modelFigure 12 The open-loop transfer function of couple water tankFigure 13 Open-loop control systemFigure 14 Close-loop control systemFigure 15 P-plus-feed forward close-loop control systemFigure 16 Step response of a first order system- time constantFigure 17 PI-plus-feed forward close-

24、loop control systemFigure 18 Cascade and feedback control systemFigure 19 The block of whole systemFigure 20 Cascade systemFigure 21 The block diagram of Couple water tank water level PI-plus-feedforward Control systemFigure 22The block diagram of Proportional controllerFigure 23 The block diagram o

25、f Proportional integral controllerFigure 24 The block diagram of Proportional controllerFigure 25 The block diagram of couple water tank PI controllerFigure 26 The system amplitude oscillation curveFigure27 couple water tank PI controller simulation resultsFigure 28 Digital-to-analog and analog-to-d

26、igital converterFigure 29 NetCon setFigure 30 NetCon setFigure 31 NetCon setFigure 32 NetCon setFigure 33 NetConTop setFigure 34 NetConTop setFigure 35 Calibration modelFigure 36Calibration circuit boardFigure 37 Saturation blockFigure 38 Saturation setFigure 39 Proportional control system block dia

27、gramFigure 40 P-plus-feedforward controller experiment result 1Figure 41 P-plus-feedforward controller experiment result 2Figure 42 PI-plus-feedforward control system block diagramFigure 43 PI-plus-feedforward controller experiment result 1Figure 44 PI-plus-feedforward controller experiment result 2

28、Figure 45 PI-plus-feedforward controller experiment result 3Figure 46 Cascade and feedback control system block diagramFigure 47 Cascade and feedback controller experiment result 1Figure 48 Cascade and feedback controller experiment result 2Figure 49 Cascade and feedback controller experiment result

29、 3Figure 50 Couple water tank PI-plus-feedforward control system block diagram.Figure 51 Couple water tank PI-plus-feedforward controller experiment result 1Figure 52 Couple water tank PI-plus-feedforward controller experiment result 2Figure 53 Couple water tank PI-plus-feedforward controller experi

30、ment result 3Figure 54 Couple water tank PI-plus-feedforward controller experiment result 4Chapter1. Project Overview1.1 Aim and Objectives:The aim of the project:The key aim of the project is to apply various control strategies to real-time level control of a water tank using computers.The objectiv

31、es of the project include:a) Understand the level control problem of a water tank;b) Study class and advance control methods, e.g., PID control, optimal control, adaptive control, fuzzy control, etc.c) Be familiar with the following software: Matlab, Simulink, Real-Time Workship, NetCon System;d) Si

32、mulate various control strategies (e.g., PI, PID control, optimal control, adaptive control, fuzzy control) in Simulink for closed-loop level control based on the model of a water tank;e) Simulate various control strategies (e.g., PI, PID control, optimal control, adaptive control, fuzzy control) on

33、 the NetCon System for real-time close-loop level control, based on the model of a water tank;f) Apply the simulated control strategies to a practical level control test rig.1.2 General Background:1.2.1 Single water-tank systemNow day in Inhabitant domestic water supply, beverages, food processing a

34、nd other industries the production process, we usually need to use the water tank, it need to maintain the appropriate level, neither too overflow cause waste, also cannot too little and cant meet the demand.A model of single water-tank is show as the figure one below. V1 is water drain valve. V2 is

35、 the inlet valve. The liquid level of the control requirement is h0. The water flow, which drain into the tank is controlled by V2 valve, water flow, which drains out of the tank, is controlled by V1 valve. The V1 open library is change with the needs of users. As a consequence to control the variab

36、le value of the water level h0 it is transfer to control the Water inflow. In is experiment to achieve control the inlet flow by using change the voltage which is driven the pump.Figure1. Illustrating the Analogy1.2.2 Couple water-tank systemCouple tank water is a typical model of nonlinear delay ob

37、jects, much of the controlled object in industrial whole or partial can be abstracted as mathematics model of double water tank. It has strong representation and strong industrial background. In industrial production the mathematical modeling and control strategy of couple water tank has the guiding

38、 significance in research of liquid level control system. Such as industrial boilers, mold level control. As is showed below the figure 2 is the couple water tank. The experiments require is control the bottom tank water level from the water flow coming out of the top tank.Figure2. Schematic of the

39、Coupled-Tank plant 1To be more specific, the set above two experimental sequences are aimed at:1. How to mathematically model the Coupled-Tank from first principles in order to obtain the two open-loop transfer functions characterizing the system, in the Laplace domain.2. How to linearize the obtain

40、ed non-linear equation of motion about the quiescent point of operation.3. How to design, though pole placement, a proportional-plus-integral-plus-feed forward-based controller for the Coupled-Tank system in order for it to meet the required design specifications for each configuration.4. How to imp

41、lement each configuration controller in real-time and evaluate their actual performance.Chapter2. Software Introduction2.1 MATLAB IntroductionMATLAB is a programming environment for algorithm development, data analysis, visualization, and numerical computation. Using MATLAB, you can solve technical

42、computing problems faster than with traditional programming languages, such as C, C+, and FORTRAN.You can use MATLAB in a wide range of applications, including signal and image processing, communications, control design, test and measurement, financial modeling and analysis, and computational biolog

43、y. For a million engineers and scientists in industry and academia, MATLAB is the language of technical computing 2.Key Features: High-level language for technical computing Development environment for managing code, files, and data Interactive tools for iterative exploration, design, and problem so

44、lving Mathematical functions for linear algebra, statistics, Fourier analysis, filtering, optimization, and numerical integration 2-D and 3-D graphics functions for visualizing data Tools for building custom graphical user interfaces Functions for integrating MATLAB based algorithms with external ap

45、plications and languages, such as C, C+, Fortran, Java, COM, and Microsoft ExcelMATLAB can be used in following works: (1).Creating transfer functionsA transfer function can be expressed as a numerator polynomial divided by a denominator polynomial, that is, F(s) =N(s)/D(s). The numerator, N(s), is

46、represented by a row vector, numf, the contains the coefficients of N(s). Similarly, the denominator, D(s), is represented by a row vector, denf, that contains the coefficients of D(s). We form F(s) with the command, F=tf(numf,denf). F is called a linear time-invariant (LTI) object, or transfer func

47、tion, can be used as an entity in other operations, such as addition or multiplication. (2)Time responseWe can use MATLAB to calculate characteristics of a second order system, such as damping ratio, ; natural frequency; percent overshoot, %OS; settling time, Ts; and peak time, Tp. (3)StabilityMATLAB can solve for the poles of a transfer function in order to determine stability. Also, we can use MATLAB to find the range of gain for stability by generating a loop, changing gain,