Lecture 1 & 2 - 2
Lecture 1 & 2 - 2
Lecture 1 & 2 - 2
Course Book
Feedback Control of Dynamic Systems.
Lecture Outline
What is Control Systems? Applications Implementations Salient Design Steps Chapter 1
Controls ?
Objective is to modify the behavior of a given system so that it works in accordance with our wishes. Science of designing such controllers.
One of the complicated and theoretical branch of Electrical Engineering.
Systems
Definition of Controls revolve around Systems.
What is a system? Identify systems in this room
Air-conditioners
Bracket fans Amplifiers Humans (Combination of sub-systems) Power Supply of a PC
Other Systems
Aircrafts, Missiles Automotives Nuclear Reactors Industrial Processes Robots Human Systems
Systems
Nasty Systems
Stabilizing Platform
Feedback is a must
Can you manage this
Implementation
Modern day controller
Piece of Software Housed in a PC
Chapter 1
An Overview and Brief History of Feedback Control
Gas Valve
Furnace
Q in + House Room Temperature
Figure 1.2 : Generic Components of the Elementary Feedback Control System, as identified from the above example.
Disturbance Plant Input Filter Reference + Controller Control Signal
Actuator
Process Output
Sensor
Sensor Noise
Actuator
Throttle
Sensor Speedometer
Sensor Noise
A mathematical model of our system is needed in the form of a set of quantitative relationships among the variables, while ignoring the dynamic behavior. (Figure 1.4)
w(% grade )
0.5
Control (degrees) u +
10
Case # 1
Example of an Open-Loop Control System. Controller does not use the speedometer readings.
Plant
0.5
Controller u r
1 / 10
10
Case # 2
Example of a Closed-Loop Control System. Feedback reduces the sensitivity of the speed error. Feedback scheme is shown in fig 1.6, where the controller gain has been set to 10.
0.5
Controller u
10
-
10
Ycl
Liquid Level Control: Invented in antiquity and still used today (e.g. water tank of the ordinary flush toilet) is the float valve.
Drebbelss Incubator:
Designed in 1620, to control the temperature of a furnace, used to heat an incubator. (Refer to Fig 1.7)
Fly-ball Governor:
Motivated by the desire to automatically control the speed of the grinding stone in a wind driven flour mill, Fuller (1976) used a conical pendulum, or Fly-ball governor, to measure the speed of the mill.
James Watt:
However it was adaption of these principles to the steam engine in the laboratories of James Watt that made Fly-ball Governor famous.
Fly-ball Governor
Stability Analysis:
In a paper written by Maxwell, he stated that stability depends on the roots of a certain equation having negative real parts.
Frequency Response:
To solve the problem of reducing distortion, BLACK proposed the feedback amplifier.
PID Control:
This field, characterized by processes that are not only highly complex but also nonlinear and subject to relatively long time delays between actuator and sensor, developed Potentional Integral-Derivative Control.
Root Locus:
State-Variable Design:
Much of this work was stimulated by the new field of control of artificial earth satellites, in which the ODE is a natural form for writing the model.
Classical Control:
It uses the Laplace or Fourier transforms.
Modern Control:
It is based on ODEs in state form and were introduced into the field starting in the 1960s.
End Of Lecture