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莊智清 控制工程 Chapter 1 2011 Fall 1
Chapter 1
Introduction to Control Systems
莊智清 控制工程 Chapter 1 2011 Fall 2
Chapter Contents
1. Introduction2. Brief History of automatic control3. Examples of control systems4. Engineering design5. Control system design6. Mechatronic systems7. Green engineering8. The future evolution of control systems9. Design examples10. Sequential design example: disk drive read
system11. Summary
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1.1 Introduction
Control system engineers are concerned with modeling and controlling segments of their environment, often called systems, to provide useful economic products of society.
Automotive
Off-road Vehicle
Heavy Industry
Aerospace
Weapon
Aircraft
Pneumatic System
Hydraulic System
Computer Peripheral
Control systems are everywhere Man made Nature created Many others
Modeling Understand Represent Able to predict
Controlling Analyze Design Implement Verify
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Control Engineering
A multi-disciplinary course Feedback theory Linear system analysis Network theory Communication theory
Applicable to aeronautical, chemical, mechanical, environmental, civil, and electrical engineering.
Role of control in EE curriculum Electronics Semiconductor CAD Communication Network Computer Power Instrumentation
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Control System
A control system is an interconnection of components forming a system configuration that will provide a desired system response.
A component or process to be controlled is represented by a block.
The input-output relationship represents the cause-and-effect relationship of the process.
Depending on the system configuration, there are two kinds of control systems Open-loop control system Closed-loop control system
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Open-Loop Control System
An open-loop control system utilizes a controller or control actuator to obtain the desired system response.
An open-loop system is a system without feedback.
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Closed-Loop Control System
A closed-loop control system utilizes an additional measure of the actual output to compare the actual output with the desired output response.
The measure of the output is called the feedback signal. A feedback control system is a control system that tends to
maintain a prescribed relationship of one system variable to another by comparing functions of these variables and using the difference as a means of control.
Feedback concept: foundation for control system analysis and design
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Multivariable Control System
A control system is multivariable if there are more than one input or output variables to be controlled.
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Advantages of Control Systems
Power amplification (antenna) Remote control (robot) Convenience of input form (heater) Compensation for disturbances (compact disc) Sensitivity reduction (power converter) Linearization (microsensor) Performance enhancement (communication system) Stability augmentation (fighter aircraft)
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1.2 Brief History of Control
Float regulator mechanism The Greeks began engineering feedback systems around 300 BC Ktesibios: water clock Philon of Byzantium: oil lamp Heron of Alexandria: pneumatica
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History of Control
Steam pressure and temperature controls Denis Papin: safety valve for the regulation of steam pressure Cornelis Drebbel: temperature control system
mercury
alcohol
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History of Control
Speed control Edmund Lee: speed control of windmill James Watt: flyball speed governor
At the set speed the governor operates to let just the appropriate amount of steam to the engine. Should the engine speed up, the weights on the governor (driven by the engine) would fly further outward, cutting down the steam. If the engine slows up, the weight of the revolving balls will cause the valve to open further and restore normal speed.
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History of Control
1769: Watt, steam engine and governor developed. 1800: Whitney, concept of interchangeable parts manufacturing 1868: Maxwell, ‘On governors’ formulates a differential equation
to model the governor control and hunting effect. 1877: Routh, ‘Stability of motion’ Routh-Hurwitz criterion 1892: Lyapunov, Stability theory 1913: Ford, mechanized assembly machine introduced for
automobile production. 1922: Sperry, gyro and automatic steering 192x: Minorsky, PID (proportional-integral-derivative) control 192x: Black, feedback amplifiers 1927: Bode, Network analysis and feedback amplifier design 1932: Nyquist, regeneration theory for stability analysis 1942: Ziegler & Nichols, PID tuning
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History of Automatic Control
1948: Evans, root locus 1952: MIT, Numerical control (NC) and servomechanism 1954: Devol, first industrial robot 1956: Pontryagin, optimal control 1962: Bellman, dynamic programming 1970s: state variables model, Kalman filtering, and optimal
control 1980s: robust control, adaptive control, intelligent control
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1.3 Examples of Control Systems
Feedback amplifier Previous achievements: Armstrong and de Forest, positive
feedback amplifiers Harold S. Black in 1921, negative feedback amplifier Objective: Linearizing, stabilizing, and improving the
amplifiers Approach: Feeding systems output back to the input as a
method of system control thus helping to eliminate distortion in telecommunications and to extend the frequency range of the amplifier.
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Examples of Control Systems
Automobile steering control system
Feedback is essential
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Examples of Control Systems
Intelligent vehicle and intelligent transportation Intelligent infrastructure + intelligent vehicles
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Examples of Control Systems
Robots, robots, robots http://www.youtube.com/watch?v=EzjkBwZtxp4 http://www.youtube.com/watch?v=b2bExqhhWRI http://www.youtube.com/watch?v=2STTNYNF4lk http://www.youtube.com/watch?v=Q3C5sc8b3xM http://www.youtube.com/watch?v=9vwZ5FQEUFg http://www.youtube.com/watch?v=H8bziuSFvW4
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Control System Examples
Float level regulation Temperature control (refrigerator, air-conditioner, heater) Household appliances Automation and robots Home automation Automobile control and intelligent transportation system (ITS) Semiconductor manufacturing industry Entertainment Computer peripherals Power industry Metallurgical industry Automatic warehousing and inventory control Biomedical and biological control Social, economic, and political … many many others
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National Income System
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Economics and Control
The Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel 1999 was awarded to Prof. Robert A. Mundell.
"for his analysis of monetary and fiscal policy under different exchange rate regimes and his analysis of optimum currency areas“ Economical policy exchange rates and capital
mobility The Effects of Stabilization Policy Optimum Currency Areas
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Invention of the Transistor
In 1956 John Bardeen, Walter Houser Brattain, and William Bradford Shockley were honored with the Nobel Prize in Physics "for their researches on semiconductors and their discovery of the transistor effect".
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The key: understanding of the process of the electron mobility in a semiconductor. It was realized that if there was some way to control the flow of the electrons from the emitter to the collector of this newly discovered diode, one could build an amplifier. For instance, if you placed contacts on either side of a single type of crystal the current would not flow through it. However if a third contact could then "inject" electrons or holes into the material, the current would flow.
Their understanding solved the problem of needing a very small control area to some degree. Instead of needing two separate semiconductors connected by a common, but tiny, region, a single larger surface would serve. The emitter and collector leads would both be placed very close together on the top, with the control lead placed on the base of the crystal. When current was applied to the "base" lead, the electrons or holes would be pushed out, across the block of semiconductor, and collect on the far surface. As long as the emitter and collector were very close together, this should allow enough electrons or holes between them to allow conduction to start.
莊智清 控制工程 Chapter 1 2011 Fall
Cell Control
Cell control A cell consists of millions of intracellular molecules, which serve as
building blocks for its structure and functions. These interactions among these building blocks display the property of self organization which intrinsically serves as the foundation of the networks of signaling and regulatory pathways.
It is through these intrinsically inter-connected networks that a cell, the basic unit of life, senses, responses and adapts its environment. These three characteristics (large number of building blocks, self-organization due to interactions and adaptation) are commonly observed in all complex systems.
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莊智清 控制工程 Chapter 1 2011 Fall
Cell Control
The Center for Cell Control of US is working on an unprecedented approach to first utilize systems control, with therapeutic intent, to determine the parameters for guiding the cell to a directed phenotype/genotype which will then be followed by in depth study, using nanoscale modalities, of the path by which this desired state is achieved. This approach will enable engineering systems that can be applied towards the regulation of a spectrum of cellular functions, such as cancer eradication, controlling viral infection onset, and stem cell differentiation.
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1.4 Engineering Design
Engineering design is a complex process in which both creativity and analysis play major roles.
Design is a process of conceiving or inventing the forms, parts, and details of a system to achieve a specific purpose.
The design steps are1. Determine a need arising from the values of various groups,
covering the spectrum from public policy makers to consumer2. Specify in detail what the solution to that need must be and to
embody the value3. Develop and evaluate various alternative solutions to meet these
specifications4. Decide which one is to be designed in detail and fabricated
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Engineering Design
Engineering design must also consider the constraint of time. The design of technical systems aims to achieve appropriate
design specifications and rests on four characteristics: Complexity Trade-off Design gaps Risk
Tasks in an engineering design may involve Analysis Synthesis Optimization
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1.5 Control System Design
The design of control systems is a specific example of engineering design.
The goal of control system engineering is to obtain the configuration, specifications, and identification of the key parameters of a proposed system to meet an actual need.
The design process is iterative.
Computer-aided tools are often used to speed up the design.
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1.6 Mechatronic Systems
Mechatronics: the synergistic integration of mechanical, electrical, and computer systems.
Physical system modeling
Sensors and actuators
Software and data acquisition
Signals and systems
Computers and logic systems
Mechatronics
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Mechatronics
Applications of mechatronics to engineering systems Hybrid fuel vehicles Wind power Microelectromechanical systems (MEMS) BioMEMS Embedded computer
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MEMS (MicroElectroMechanical System)
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1.7 Green Engineering
Green engineering: to design products that will minimize pollution, reduce the risk to human health, and improve the environment. Engineer processes and products holistically, use system analysis, and
integrate environmental impact assessment tools Conserve and improve natural ecosystems while protecting human health and
well-being. Use life-cycle thinking in all engineering activities Ensure that all material and energy inputs and outputs are as inherently safe
and benign as possible Minimize depletion of natural resources Strive to prevent waste Develop and apply engineering solutions, while being cognizant of local
geography, aspirations, and cultures Create engineering solutions beyond current or dominant technologies;
improve, innovate, and invent technologies to achieve sustainability Actively engage communities and stakeholders in development of engineering
solutions Green engineering applications: environmental monitoring, energy
storage system, power quality monitoring, solar energy, and wind energy.
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1.8 The Future Evolution of Control Systems
Goal of control systems: provides extensive flexibility and a high level of autonomy.
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1.9 Design Examples
Smart grid control systems
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Rotating Disc Speed Control Design Example
Applications of rotating disk speed control: CD/DVD, hard disc, …
Goal of turntable speed control: ensure that the actual speed of rotation is within a specified percentage of the desired speed.
Open-loop scheme (without feedback) Turntable DC motor Amplifier Battery
Closed-loop scheme Turntable (process) DC motor (actuator) Amplifier (control device) Tachometer (sensor) Battery (power supply)
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Open-Loop Turntable Speed Control
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Closed-Loop Turntable Speed Control
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Design Examples: Insulin Delivery Control System
Control systems have been utilized in the biomedical field to create implanted automatic drug-delivery systems to patients.
Automatic systems can be used to regulate blood pressure, blood sugar level, and heart rate.
Open-loop drug delivery system Based on the mathematical model
of the dose-effect relationship As miniaturized glucose sensors
are not available, the best solutions rely on individually programmable, pocket-sized insulin pumps that can deliver insulin according to a preset time history.
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Closed-Loop Insulin Delivery Control System
1. Establish control goals: design a system to regulate the blood sugar concentration of a diabetics.
2. Identify the variables to control: blood glucose concentration.3. Write the specifications for the variables: provide a blood
glucose level for the diabetic that closely approximates the glucose level of a healthy person.
4. Establish the system configuration and identify the actuator: use a sensor to measure the actual glucose level and compare that level with the desired level, thus turning the motor pump on when it is required.
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1.9 Sequential Design Example: Disk Drive Read System
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Disk Drive Read System
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Disk Drive Control
1. Establish control goals: position the reader head in order to read the data stored on a track on the disk.
2. Identify the variables to control: position of the reader head.3. Write the specifications for the variables: the position accuracy
is 1 mm and the time for the reader head to move is 50 ms.4. Establish the system configuration and identify the actuator: use
of sensor, actuator, control processor, and feedback.
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Summary
A control system Consisting of interconnected components Designed to achieve a desired purpose
Control systems can be open-loop or closed-loop. The use of feedback (conceptually and pragmatically) is
important. Control system design is essentially an iterative process. Knowledge of feedback and control is essential in many
engineering disciplines.
