This document discusses fundamental control theory concepts. It introduces control systems and defines them as systems that control an output to a particular value, sequence, or event based on inputs. Open and closed loop systems are described, with closed loop utilizing feedback to correct errors. The basic elements of open and closed loop systems are also outlined, including the comparison element, control law implementation element, correction element, process, and measurement element. Finally, motor shaft speed control is provided as a case study example.

1. CHAPTER 1 : FUNDAMENTAL OF CONTROL THEORY
INTRODUCTION
GP 619 –
ADVANCED
CONTROL
SYSTEM CONTROL
PROCESSES
Prepared by
OPEN & CLOSED
LOOP SYSTEM Mr. Mohd Taufik Rezza B Mohd
Foudzi
BASIC ELEMENT
CASE STUDY

2. INTRODUCTION

3. CONTROL SYSTEM
A control system can be thought of as a system which
for some particular input or inputs is used to control its
output to some particular value , give a particular
sequence of events or give an event if certain
conditions are met .
• Control a variable to obtain the required value
•Control the sequence of events
•Control whether an event occurs or not

4. OPEN & CLOSED LOOP SYSTEM
• No correction for errors in the output which might result from
extraneous disturbances
• relatively simple and consequently cheap with generally good
reliability

5. OPEN & CLOSED LOOP SYSTEM
• The input to the process depends on the deviation of the
measuring value fed back from the output of the system from
the required set point, the difference between them being
determined by a comparison element.
• There is a constant comparison of the actual and required
setpoint In this situation there is feedback
LOGO

6. OPEN & CLOSED LOOP SYSTEM
+ set value - feedback value = error
• the comparison element in the closed-loop control system is
represented by a circular symbol with a + opposite the set value
input and a - opposite the feedback signal.
• This difference between the set value and feedback value, the
so-called error
LOGO

7. BASIC ELEMENT (OPEN LOOP)
•Control element
This determines the action to be taken as a result of the input of the required value
signal to the system.
•Correction element
This has an input from the controller and gives an output of some action designed
to change the variable being controlled.
•Process
This is the process of which a variable is being controlled. There is no changing of
the control action to account for any disturbances which change the output variable.

8. BASIC ELEMENT
(CLOSED LOOP)
LOGO

9. BASIC ELEMENT
(CLOSED LOOP)
1. Comparison element
This element compares the required value of the variable being controlled
with the measured value of what is being achieved and produces an error
signal:
error = required value signal - measured actual value signal
2. Control law implementation element
The control law element determines what action to take when an error
signal is received. The control law used by the element may be just to
supply a signal which switches on or off when there is an error, as in a room
thermostat, or perhaps a signal which is proportional to the size of the error
so that if the error is small a small control signal is produced and if the error
is large a large proportional control signal is produced. Other control laws
include integral mode where the control signal continues to increase as
long as there is an error and derivative mode where the control signal is
proportional to the rate at which the error is changing.
LOGO

10. BASIC ELEMENT
(CLOSED LOOP)
The term control unit or controller is often used for the
combination of the comparison element
3. Correction element
The correction element or, as it is often called, the final control element, produces
a change in the process which aims to correct or change the controlled condition.
The term actuator is used for the element of a correction unit that provides the
power to carry out the control action. Examples of correction elements are
directional control valves which are used to switch the direction of flow of a fluid and
so control the movement of an actuator such as the movement of a piston in a
cylinder. Another example is an electric motor where a signal is used to control the
speed of rotation of the motor shaft
LOGO

11. BASIC ELEMENT
(CLOSED LOOP)
4 . Process
The process is the system in which there is a variable that is being controlled, e.g. it
might be a room in a house with the variable of its temperature being controlled.
5. Measurement element
The measurement element produces a signal related to the variable condition of the
process that is being controlled. For example, it might be a temperature sensor with
suitable signal processing.
1. Feedback path
Feedback is a means whereby a signal related to the actual condition being achieved is fed
back to modify the input signal to a process. The feedback is said to be negative when the
signal which is fed back subtracts from the input value. It is negative feedback that is required
to control a system. Positive feedback occurs when the signal fed back adds to the input
signal.
2. Forward path
The term forward path is used for the path from the error signal to the output. In before these
forward path elements are the control law element, the correction element and the process
element.
LOGO

12. CASE STUDY
1.CONTROL OF SPEED OF ROTATION OF A MOTOR SHAFT

13. CASE STUDY
1.CONTROL OF SPEED OF ROTATION OF A MOTOR SHAFT
LOGO