Text Books: K. Ogata, Modern Control Engineering,. 3rd edition, Prentice Hall,
1997. References: • N. Nise, Control Systems Engineering, John Wiley. & Sons ...
Automatic Control Introduction
Dr. Aly Mousaad Aly Department of Mechanical Engineering Faculty of Engineering, Alexandria University
Instructor • • • •
Instructor: Dr. Aly Mousaad Aly Classes and office hours: every Tuesday Email:
[email protected] Teaching assistants: Eng Khaled Hassib (ME221) Eng. Eng. Nermine E. Shehata (EE290) Eng. Sherif Omar (EE290)
Slides 1: Introduction
2
Course Materials Slid Will b Slides: be available il bl online li . Text Books: K. Ogata, Modern Control Engineering, 3rd edition, Prentice Hall, 1997. References: • N. Nise, Control Systems Engineering, John Wiley & Sons, Inc., 2011. • R.C. Dorff and d R.H. Bishop, h Modern d Controll Systems, 11th ed. Pearson Education Inc., 2008. Slides 1: Introduction
3
Grading • • • •
Class participation, quizzes and assignments First midterm exam Second midterm exam Final examination
Slides 1: Introduction
4
Why to study “Automatic Automatic Control Control”?? • The study of automatic control is essential for students pursuing degrees in many engineering disciplines (mechanical, electrical, structural, aerospace, p biomedical, or chemical). ) • Applications of automatic control include, but not limited to to, aircraft aircraft, robots robots, civil engineering structures, process control, …., etc. • Automatic i controll h has played l d a vital i l role l iin the h advance of engineering and science. Slides 1: Introduction
5
What is “Control”? Control ? • Make k some object bj ((called ll d system, or plant) l ) behave as we desire. • Imagine “control” around you! Room temperature p control Car driving Voice volume control Balance of bank account “C “Control” l” ((move)) the h position i i off the h pointer i etc. Slides 1: Introduction
6
What is “Automatic Automatic Control Control”?? • N Not manual! l! • Why do we need automatic control? Convenient (room temperature, laundry machine) Dangerous (hot/cold places, space, bomb removal) Impossible for human (nanometer scale precision positioning, work inside the small space that human cannott enter, t huge h antennas t control, t l elevator) l t ) It exists in nature. (human body temperature control) High efficiency (engine control) • Many examples of automatic control around us Slides 1: Introduction
7
Example: temple doors opened by fire on an altar Hero (or Heron) of Alexandria (10–70 AD)
Slides 1: Introduction
8
Example: vending machine
Heron's ' COIN CO automat
Slides 1: Introduction
9
Example: laundry machine A laundry machine washes clothes, by setting a p g program. Program setting (Input)
Laundry Machine
Washed clothes (Output)
A laundryy machine does not measure how clean the clothes become. C t l without Control ith t measuring i d devices i ((sensors)) are called open-loop control. Slides 1: Introduction
10
Open loop control systems Open-loop Advantages: Ad t • Simple construction and ease of maintenance. • There is no stability concern concern. • Convenient when output is hard to measure or measuring the output precisely is economically not feasible. (For example, l iin the h washer h system, iit would ld b be quite i expensive i to provide a device to measure the quality of the washer's output, p cleanliness of the clothes). ) Disadvantages: • Disturbances and changes in calibration cause errors, and th output the t t may b be diff differentt ffrom what h t iis d desired. i d • Recalibration is necessary from time to time. Slides 1: Introduction
11
Closed loop (feedback) control Closed-loop In this hi approach, h the h quantity i to b be controlled, ll d say C, is measured, compared with the desired value, R, and d th the error b between t th the ttwo, E = R - C used d tto adjust C. This means that the control action is somehow dependent on the output output.
. Slides 1: Introduction
12
Example: autopilot mechanism Its purpose is i to maintain i i a specified ifi d airplane heading, despite atmospheric changes. h It performs f thi this ttaskk b by continuously measuring the actual airplane heading heading, and automatically adjusting the airplane control surfaces (rudder ailerons, (rudder, ailerons etc etc.)) so as to bring the actual airplane heading into correspondence with the specified heading. Slides 1: Introduction
13
Example: antenna azimuth
Slides 1: Introduction
14
Example: antenna azimuth
Slides 1: Introduction
15
Feedback and Feedforward • FFeedback db k mechanism: h i Abilit off a machine Ability hi tto self-correct its operation by using some part of its output as input input. • Feedforward mechanism: Ability of a machine to examine the raw materials that come to it and then decide what operations to perform. Lettersorting machines in post offices are of this type. The machine sorts a letter by reading the zip code on the address and then sending the letter to the appropriate subsystem subsystem. (other examples include, include metro gate, automatic coin machine, etc.). Slides 1: Introduction
16
Basic elements of control loop Ref.
Error Controller
Actuator
Disturbance Input Output Plant
Sensor
The role of the controller is to make the output following the reference in a “satisfactory” satisfactory manner even under disturbances. Slides 1: Introduction
17
Example: playing sport Better Sensors Provide better Vision
Better Actuators Provide more Muscle
Better Control Provides more finesse by combining sensors and actuators in more intelligent ways
Slides 1: Introduction
18
Course goals Ref.
Error Controller
Actuator
Disturbance Input Output Plant
Sensor
Implementation Modeling Controller
Design Slides 1: Introduction
Mathematical model
Analysis
19
Procedure
Slides 1: Introduction
20
Summary • Introduction: Control essentiality Examples of control systems Open loop versus closed loop control systems • Next Lecture: Laplace Transformation Review
Slides 1: Introduction
21
