electronic and communication engineering technology

51.1 The definition of the control and automatic control system ...51.2 The structure of a typical automatic control system ...71.3 Difference between closed-loop and open-loop system ..

HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION

FACULTY FOR HIGH QUALITY TRAINING

FINAL PROJECT AUTOMATIC CONTROL SYSTEMS

LƯƠNG NGỌC PHƯƠNG QUỲNHStudent ID: 19161050

VÕ MINH NHỰTStudent ID: 19161042

Major: ELECTRONIC AND COMMUNICATIONENGINEERING TECHNOLOGY

Advisor: VŨ VĂN PHONG, PhD

Ho Chi Minh City, June 2022

HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION

FACULTY FOR HIGH QUALITY TRAINING

FINAL PROJECT

LƯƠNG NGỌC PHƯƠNG QUỲNHStudent ID: 19161050

VÕ MINH NHỰTStudent ID: 19161042

Major: ELECTRONIC AND COMMUNICATIONENGINEERING TECHNOLOGY

Advisor: VŨ VĂN PHONG, PhD

Ho Chi Minh City, June 2022

Table of Contents

TASK 1: Basic concepts of the Automatic Control System 5

1.1 The definition of the control and automatic control system 5

1.2 The structure of a typical automatic control system 7

1.3 Difference between closed-loop and open-loop system 9

1.4 Consider the liquid-level control system in Fig.5, please list the components of this system and make block diagram of this system This system is open-loop or closed-loop system? 11

TASK 2: Mathematical Model 11

2.1 Block Diagram 11

2.2Using Matlab to find the closed-loop transfer function 12

2.3 State-space equation 14

TASK 3: Transient Response and stability Analysis 17

3.1 Analyse the behaviour and response of the first-order system as follow: 17

3.2 Consider the Hubbe Space Telescope is modelled in Fig.8 Analyse the behavior and response of this system .18

3.3 Taken into account the following system 20

3.4 Consider the Disk Drive Read System in Figure 9 22

TASK 4: PID Controller Design 25

4.1 Please explain 25

4.2 Let us consider the following system 31

4.3 Consider a system in the following figure 39

4.4 The DC Motor in Fig.31 is modelled in the following transfer function 42

Reference 45

Table of Figure and Table

Figure 1 Figure of Task 1 5

Figure 2 A control system 5

Figure 3 Automobile interior cabin temperature control system 7

Figure 4 The structure of automatic control system 7

Figure 5 11

Figure 6 Block Digram of system Fig 5 11

Figure 7 Structure of Pneumatic System 12

Figure 8 Block diagram of Pneumatic system 12

Figure 9 13

Figure 10 Using Matlab to determine the transfer function 13

Figure 11 Enter Transfer funtion into Matlab 14

Figure 12 Mechanical system 14

Figure 13 Simulate System with Simulink 15

Figure 14 Simulate System with Simulink 15

Figure 15 The Waveform in Simulink 16

Figure 16 Simulate with Simulink 17

Figure 17 Simulate the system in Matlab with unity step signal 18

Figure 18 Block diagram of the system 20

Figure 19 21

Figure 20 Plot the poles and zeros 21

Figure 21 22

Figure 22 22

Figure 23 The mathematical form of PID algorithm 26

Figure 24 P-control behavior is mathematically illustrated 27

Figure 25 P-controller output for step input 28

Figure 26 I-control behavior is mathematically illustrated 29

Figure 27 I-controller output for step input .30

Figure 28 D-control behavior is mathematically illustrated 30

Figure 29 D-controller output for step input 31

Figure 30 Blcok Diagram of this system 31

Figure 32 Block Diagram of the system 39

Figure 31 Model of the DC Motor with the inertial load 42

Table 1 Comparison chart 10

TASK 1: Basic concepts of the Automatic Control System

Figure 1 Figure of Task 1Before studying the automatic control system, there are several concepts of controlfiled that need to understand clearly The requirements for this task are that students have

to answer the following questions:

1.1 The definition of the control and automatic control system

Please provide the definition of the control and automatic control; and give a realspecific example of automatic control

What is a control system?

A control system is a system capable of monitoring and regulating the operation of aprocess or a plant The study of control system is essentially a study of an importantaspect of systems engineering and its applications A control system consists ofsubsystems and processes (or plants) assembled for the purpose of controlling the outputs

of the process For example, a furnace produces heat as a result of the flow of fuel In thisprocess, flow of fuel in the input, and heat to be controlled is the output

Figure 2 A control systemThere are two common classes of control systems, with many variations andcombinations: logic or sequential controls, and feedback or linear controls There is also

Float

fuzzy logic, which attempts to combine some of the design simplicity of logic with theutility of linear control Some devices or systems are inherently not controllable.What is a automatic control system?

In a manual control system a machine will be operated by a person but in the case of

an automatic control system machine will do the operation automatically The automaticcontrol system has a controller so it can perform the operation on its own Basically, thecontrol system is a combination of elements and subsystem which needs to maintain aquantity The control system can maintain a process with the help of feedback control,this would help to maintain the specific variables close to the required values So thecontrol system can meet the requirement of the process by adjusting the selectedvariables in the system The feedback control can make use of an output of the system toinfluence the input of the same system The automatic control system would haveelectronic equipment and it uses current and voltage to communicate Control will beimplemented in the sensors, valves, and other equipment in the process

The automatic control system will use, for the regulation and quality control ofprocesses and the environment The control system is used in many industrial processes,

a process is a device, plant, or system which is under control The process control is done

by a control system, the control system would convert the variable to the requiredvariable There are manual and automatic control systems if a human operator is required

to give input throughout the process then it is manual control In an automatic controlsystem, there will be a controller which can replace the human operator and this will bevery useful and this controller is set to control the process accurately In most cases, thefunction of the control system is to control the physical variables such as temperature,voltage, frequency, flow rate, current, position, speed, etc, and all these are called thecontrolled variables[1]

Example: Automobile interior cabin temperature control system

Many luxury automobiles have thermostatically controlled air-conditioning systemsfor the comfort of the passengers Sketch a block diagram of an air-conditioning systemwhere the driver sets the desired interior temperature on a dashboard panel Identify thefuntion of each element of the thermostatically controlled cooling system[2]

Figure 3 Automobile interior cabin temperature control system1.2 The structure of a typical automatic control system

Please describe the structure of a typical automatic control system Please list thetypical components and their function?

https://infopedia.su/16xd750.html

The structure of a typical automatic control system include block controller, sensor,actor, and plant

Figure 4 The structure of automatic control system

In the controlled behaviour approach the model describes the behaviour of the plantand the controller joined together For the implementation the control algorithm has to beextracted from the combined model

The logic controller approach tries to define the inputoutput behaviour of thecontroller, which satisfies all the system requirements Using this method the controlprogram can be deduced directly from the obtained I/Obehaviour This approach leads tothe physical implementation of the control program, but simulation is required to validatethe closed-loop behaviour.

The control theoretic approach has been investigated by numerous research teamsand is getting more and more popular The approach adopts the controller synthesisparadigm from control theory for continuous systems A decomposition of an automationsystem leads to a structure very similar to a control loop in control engineering (Fig 4).The approach is based on separate models of plant and controller[3]

The typical components and their function?

Automatic control systems may be classified as servo-mechanisms, process controlsystems and regulators, but whatever the classification be, the same principles ofoperation are common to them all Every ACS should contain five main components.They are: a driver or reference input, an error detector, control elements, a controlledquantity and feedback path elements The basic control system operation may bedescribed by the simple block diagram[4]:

The reference input or driver sets the desired level or position of controlled quantity

C in this system The controlled quantity C is the resulting level or position of variableparameter, which is the position to be controlled by this ACS The feedback pathelements H supply a feedback signal B that indicates the level of the controlled quantity

C The error detector receives the feedback signal B and compares it with the inputcommand signal R; any error (or difference between B and R) produces an output or

resulting signal E Control elements G receive, amplify and transform the output signal E

to maintain the controlled quantity at the desires level[4]

1.3 Difference between closed-loop and open-loop system

Basis For

Comparison

Open Loop System Closed Loop System

Definition The system whose

control action is free fromthe output is known as theopen loop control system

In closed loop, theoutput depends on thecontrol action of thesystem

Other Name Non-feedback

Construction Simple Complex

Reliability Non-reliable Reliable

Accuracy Depends on

calibration

Accurate because offeedback

Stability Stable Less Stable

Optimization Not-Possible Possible

Calibration Difficult Easy

System

Disturbance

Affected Not-affected

Linearity Non-linear Linear

Examples Traffic light,

automatic washingmachine, immersion rod,

TV remote etc

Air conditioner,temperature controlsystem, speed andpressure control system,refrigerator, toaster

Table 1 Comparison chartExample for Open Loop Control System:

The automatic washing machine is the example of the open loop system Theoperator manually sets the operating time of the machine The machine stops operatingafter the set time, even the desire cleanliness of clothes are not obtained This happensbecause the machine has no feedback system which signals the control action of thesystem for desired output

Example for Closed Loop Control System:

Suppose in the above example of closed dryer we are using the transducer whichsenses the dryness of the clothes and provides the feedback signal to the controllerrelating to dryness Here the dryness is the output of the system The sensor act as afeedback of the system The sensor gives the signal to the controller of the machine, andhence the dryer provides the desired output

Figure 17 Simulate the system in Matlab with unity step signal3.2 Consider the Hubbe Space Telescope is modelled in Fig.8 Analyse thebehavior and response of this system.

Fig 8: The block-diagram of the systemIgnore the effect of disturbance, please determine the transfer functionbetween Y(s) and R(s)

K= ωn =2.1025

�1=2�� =1.5�With obtained K and K1, please find the steady state error with unity stepsignal

���=lim

�→1

11+ �(�)=0.5Simulating the system in Matlab with input is unity step signal

3.3 Taken into account the following system

Figure 18 Block diagram of the system

• Find the poles and zeros of the closed-loop system in Figure 18

A(s)B(s)The poles: B(s) = 0

Figure 19

Figure 20 Plot the poles and zeros

• Based on the position of poles on complex plane, please check the stability of thesystem

Because the poles of the transfer function are all to the left of the complexplane ( s = -2; -0.5 +1.323j; -0.5-1.232j)

→ the transfer function is stable

• Simulate the system with unity step input by Matlab/Simulink Comment theobtained results

Figure 21

Figure 22

→ The transfer function is stable, according to the results Although it willtake a long time to stabilize (it takes up to 15 seconds for the transfer function tobecome stable)

3.4 Consider the Disk Drive Read System in Figure 9

Fig 9: Disk drive read system

Choose Kp = 20 and Kp = 100

+ Kp = 20

+ Kp = 100

→ Evaluate the stability of the system with P controller:According to Hurwitz criterion for the system to be stable, K must be less than 84 and greater than 0

Routh-We discover that the system is unstable when K is bigger than 84 (exactly equal to 100)

As a result, the PID controller is very important balancing the stable system

TASK 4: PID Controller Design

4.1 Please explain

What is the PID controller?

A proportional–integral–derivative controller (PID controller or three-term controller)

is a control loop mechanism employing feedback that is widely used in industrial controlsystems and a variety of other applications requiring continuously modulated control APID controller continuously calculates an error value e(t) as the difference between adesired setpoint (SP) and a measured process variable (PV) and applies a correctionbased on proportional, integral, and derivative terms (denoted P, I, and D respectively),hence the name

It is important to note that cost benefit ratio obtained through the PID controller isdifficult to achieve by other controllers It is found that 97% of the regulatory controllers

in industry use PID algorithm The PID controller is popularly known as three termcontroller- the Proportional (P), Integral (I) and Derivative (D) The desired closed-loopsystem performance can be achieved with an appropriate adjustment of controller settings.This procedure is known as controller tuning Hundreds of tools, methods and theories

are available for tuning the PID controller However, finding optimal parameters for thePID controller is still a tricky task, in practice still the trial and error method is used fortuning process by the control engineers The controller can provide optimized controlaction, and minimized error performance with optimum tuning of the three parameters inthe PID controller algorithm The mathematical form of PID algorithm is represented inFig.23 [5].

Figure 23 The mathematical form of PID algorithm

In practical terms, PID automatically applies an accurate and responsive correction

to a control function An everyday example is the cruise control on a car, whereascending a hill would lower speed if constant engine power were applied Thecontroller's PID algorithm restores the measured speed to the desired speed with minimaldelay and overshoot by increasing the power output of the engine in a controlled manner.The roles of the P, I, D of PID control in the control system

Proportional (P) Control:

One type of action used in PID controllers is the proportional control Proportionalcontrol is a form of feedback control It is the simplest form of continuous control thatcan be used in a closed-looped system P-only control minimizes the fluctuation in theprocess variable, but it does not always bring the system to the desired set point Itprovides a faster response than most other controllers, initially allowing the P-onlycontroller to respond a few seconds faster However, as the system becomes morecomplex (i.e more complex algorithm) the response time difference could accumulate,allowing the P-controller to possibly respond even a few minutes faster Although the P-only controller does offer the advantage of faster response time, it produces deviationfrom the set point This deviation is known as the offset, and it is usually not desired in aprocess The existence of an offset implies that the system could not be maintained at thedesired set point at steady state It is analogous to the systematic error in a calibrationcurve, where there is always a set, constant error that prevents the line from crossing theorigin The offset can be minimized by combining P-only control with another form ofcontrol, such as I- or D- control It is important to note, however, that it is impossible to