1. Chapter 1: Introduction to Control Systems Objectives
In this chapter we describe a general process for designing a control system.
A control system consisting of interconnected components is designed to achieve a desired purpose. To understand the purpose of a control system, it is useful to examine examples of control systems through the course of history. These early systems incorporated many of the same ideas of feedback that are in use today.
Modern control engineering practice includes the use of control design strategies for improving manufacturing processes, the efficiency of energy use, advanced automobile control, including rapid transit, among others.
We also discuss the notion of a design gap. The gap exists between the complex physical system under investigation and the model used in the control system synthesis.
The iterative nature of design allows us to handle the design gap effectively while accomplishing necessary tradeoffs in complexity, performance, and cost in order to meet the design specifications.

2. Introduction
System – An interconnection of elements and devices for a desired purpose.
Control System – An interconnection of components forming a system configuration that will provide a desired response.
Process – The device, plant, or system under control. The input and output relationship represents the cause-and-effect relationship of the process.

3. Introduction
Open-Loop Control Systems utilize a controller or control actuator to obtain the desired response.
Closed-Loop Control Systems utilizes feedback to compare the actual output to the desired output response.
Multivariable Control System

4. History

5. History
18th Century James Watt’s centrifugal governor for the speed control of a steam engine.
1920s Minorsky worked on automatic controllers for steering ships.
1930s Nyquist developed a method for analyzing the stability of controlled systems
1940s Frequency response methods made it possible to design linear closed-loop control systems
1950s Root-locus method due to Evans was fully developed
1960s State space methods, optimal control, adaptive control and
1980s Learning controls are begun to investigated and developed.
Present and on-going research fields. Recent application of modern control theory includes such non-engineering systems such as biological, biomedical, economic and socio-economic systems
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6. Examples of Modern Control Systems
(a) Automobile steering control system.
(b) The driver uses the difference between the actual and the desired direction of travel
to generate a controlled adjustment of the steering wheel.
(c) Typical direction-of-travel response.

7. Examples of Modern Control Systems

8. Examples of Modern Control Systems

9. Examples of Modern Control Systems

10. Examples of Modern Control Systems

11. Examples of Modern Control Systems

12. Increasing Affordability and Military Capability
Design Example
ELECTRIC SHIP CONCEPT
Vision
Electrically
Reconfigurable
Ship
All
Electric
Ship
Integrated
Power
System
Technology
Insertion
Warfighting Capabilities
Increasing Affordability and Military Capability
Reduced manning
Automation
Eliminate auxiliary systems (steam, hydraulics, compressed air)
Electric Drive
Reduce # of Prime Movers
Fuel savings
Reduced maintenance
Ship
Service
Power
Main Power
Distribution
Propulsion
Motor
Drive
Generator
Prime
Mover
Conversion
Module

13. Design Example
CVN(X) FUTURE AIRCRAFT CARRIER

14. Design Example

15. Design Example

16. Design Example

17. Design Example

20. Design Example

21. Sequential Design Example

22. Part II AUTOMATION AND CONTROL TECHNOLOGIES
Chapters:
Introduction to Automation
Industrial Control Systems
Hardware Components for Automation and Process Control
Numerical Control
Industrial Robotics
Discrete Control Using Programmable Logic Controllers and Personal Computers
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23. Ch 4 Introduction to Automation
Sections:
Basic Elements of an Automated System
Advanced Automation Functions
Levels of Automation
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24. Automation and Control Technologies in the Production System
Fig. 4-1
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25. Automation Defined
Automation is the technology by which a process or procedure is accomplished without human assistance.
Basic elements of an automated system:
Power - to accomplish the process and operate the automated system
Program of instructions – to direct the process
Control system – to actuate the instructions
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26. Elements of an Automated System
Fig. 4-2
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27. Electricity - The Principal Power Source
Widely available at moderate cost
Can be readily converted to alternative forms, e.g., mechanical, thermal, light, etc.
Low level power can be used for signal transmission, data processing, and communication
Can be stored in long-life batteries
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28. Power to Accomplish the Automated Process
Power for the process
To drive the process itself
To load and unload the work unit
Transport between operations
Power for automation
Controller unit
Power to actuate the control signals
Data acquisition and information processing
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29. Program of Instructions
Set of commands that specify the sequence of steps in the work cycle and the details of each step
Example: CNC part program
During each step, there are one or more activities involving changes in one or more process parameters
Examples:
Temperature setting of a furnace
Axis position in a positioning system
Motor on or off
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30. Decision-Making in a Programmed Work Cycle
The following are examples of automated work cycles in which decision making is required:
Operator interaction
Automated teller machine
Different part or product styles processed by the system
Robot welding cycle for two-door vs. four door car models
Variations in the starting work units
Additional machining pass for oversized sand casting
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31. Features of a Work Cycle Program
Number of steps in the work cycle
Manual participation in the work cycle (e.g., loading and unloading workparts)
Process parameters - how many must be controlled?
Operator interaction - does the operator enter processing data?
Variations in part or product styles
Variations in starting work units - some adjustments in process parameters may be required to compensate for differences in starting units
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32. Control System – Two Types
Closed-loop (feedback) control system – a system in which the output variable is compared with an input parameter, and any difference between the two is used to drive the output into agreement with the input
Open-loop control system – operates without the feedback loop
Simpler and less expensive
Risk that the actuator will not have the intended effect
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33. (a) Feedback Control System and (b) Open-Loop Control System
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34. Positioning System Using Feedback Control
A one-axis position control system consisting of a leadscrew driven by a dc servomotor and using an optical encoder as the feedback sensor
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35. When to Use an Open-Loop Control System
Actions performed by the control system are simple
Actuating function is very reliable
Any reaction forces opposing the actuation are small enough as to have no effect on the actuation
If these conditions do not apply, then a closed-loop control system should be used
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36. Advanced Automation Functions
Safety monitoring
Maintenance and repair diagnostics
Error detection and recovery
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37. Safety Monitoring
Use of sensors to track the system's operation and identify conditions that are unsafe or potentially unsafe
Reasons for safety monitoring
To protect workers and equipment
Possible responses to hazards:
Complete stoppage of the system
Sounding an alarm
Reducing operating speed of process
Taking corrective action to recover from the safety violation
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38. Maintenance and Repair Diagnostics
Status monitoring
Monitors and records status of key sensors and parameters during system operation
Failure diagnostics
Invoked when a malfunction occurs
Purpose: analyze recorded values so the cause of the malfunction can be identified
Recommendation of repair procedure
Provides recommended procedure for the repair crew to effect repairs
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39. Error Detection and Recovery
Error detection – functions:
Use the system’s available sensors to determine when a deviation or malfunction has occurred
Correctly interpret the sensor signal
Classify the error
Error recovery – possible strategies:
Make adjustments at end of work cycle
Make adjustments during current work cycle
Stop the process to invoke corrective action
Stop the process and call for help
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40. Levels of Automation
Device level – actuators, sensors, and other hardware components to form individual control loops for the next level
Machine level – CNC machine tools and similar production equipment, industrial robots, material handling equipment
Cell or system level – manufacturing cell or system
Plant level – factory or production systems level
Enterprise level – corporate information system
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41. Levels of Automation Fig. 4.6
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42. Open loop vs closed loop

43. Open-loop
An open-loop controller, also called a non-feedback controller, is a type of controller which computes its input into a system using only the current state and its model of the system.

44. Open-loop
A characteristic of the open-loop controller is that it does not use feedback to determine if its output has achieved the desired goal of the input. This means that the system does not observe the output of the processes that it is controlling. Consequently, a true open-loop system can not engage in machine learning and also cannot correct any errors that it could make. It also may not compensate for disturbances in the system.

45. Closed-loop
Close loop control systems use the open loop systems (as forward path) and feedback from the output to decide the input level to the open loop system. And because the input is decided based on how much away the output is from the desired level, the non idealities in forward path do not degrade the system performance. The accuracy of the output thus depends on the feedback path, which in general can be made very accurate.

46. Differences
The terms open-loop control and closed-loop control are often not clearly distinguished. Therefore, the difference between open-loop control and closed-loop control is demonstrated in the following example of a room heating system. In the case of open-loop control of the room temperature according to Figure the outdoor temperature will be measured by a temperature sensor and fed into a control device.

47. Open-loop

48. Closed-loop
In the case of closed-loop control of the room temperature as shown in Figure the room temperature is measured and compared with the set-point value. If the room temperature deviates from the given set-point value, a controller (C) alters the heat flow. All changes of the room temperature, e.g. caused by opening the window or by solar radiation, are detected by the controller and removed.

49. Closed-loop

50. The order of events to organise a closed-loop control is characterised by the following steps:
Measurement of the controlled variable
Calculation of the control error (comparison of the controlled variable with the set-point value )
Processing of the control error such that by changing the manipulated variable the control error is reduced or removed

51. Comparing open-loop control with closed-loop control the following differences are seen:

52. Closed-loop control shows a closed-loop action (closed control loop);
can counteract against disturbances (negative feedback);
can become unstable, i.e. the controlled variable does not fade away, but grows (theoretically) to an infinite value.

53. Open-loop control shows an open-loop action (controlled chain);
can only counteract against disturbances, for which it has been designed; other disturbances cannot be removed;
cannot become unstable - as long as the controlled object is stable.

54. Summarising these properties we can define:
Systems in which the output quantity has no effect upon the process input quantity are called open-loop control systems.
Systems in which the output has an effect upon the process input quantity in such a manner as to maintain the desired output value are called closed-loop control systems.