dr. tarek a. tutunji microcontroller systems … · bode plots nyquist stability ... considered...
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D R . T A R E K A . T U T U N J I
M I C R O C O N T R O L L E R S Y S T E M S
P H I L A D E L P H I A U N I V E R S I T Y
2 0 1 7
Controllers Overview
Control Systems
The control system is at the heart of mechatronic systems and its selection is arguably the most critical decision in the design process.
The controller selection involves two inter-dependent parts:
The control method (i.e. software)
The physical controller (i.e. hardware)
O P E N V S . C L O S E D L O O P C O N T R O L
P R O C E S S V S . M O T I O N C O N T R O L
T R A N S I E N T A N D S T E A D Y S T A T E S P E C I F I C A T I O N S
Basic Control Concepts
Open-Loop Control
[Ref] Kilian
Closed-Loop Control
[Ref] Kilian
Control Systems Classification
Control systems are classified by application.
Process control usually refers to an industrial process being electronically controlled for the purpose of maintaining a uniform correct output.
Motion control refers to a system wherein things move. A servomechanism is a feedback control system that provides remote control motion of some object, such as a robot arm or a radar antenna.
Motion Control Examples
[Ref] Kilian
CNC Machine Robot Manipulator
Process Control Example
[Ref] Kilian
General Control System
First Order Systems
2nd Order Systems: Performance Criteria
T A R E K A . T U T U N J I
Control Methods
Dr. Tarek A. Tutunji
Control Techniques / Strategies
Classical Control
Advanced Control
Intelligent Control
Dr. Tarek A. Tutunji
Classical Control
Classical control design are used for SISO systems.
Most popular concepts are:
Bode plots
Nyquist Stability
Root locus.
PID is widely used in feedback systems.
Classical Control: On-Off Control
This is the simplest method of control. The control action has three possible outputs: on; off; no change. This method is usually used for slow-acting operations (such as a refrigeration unit).
The advantage is its ease of design and low cost. However, it cannot vary the controlled variable with precision.
On-Off Control Example
Classical Control: PID
Dr. Tarek A. Tutunji
Proportional-Integral-Derivative (PID) is the most commonly used controller for SISO systems
dt
)t(deKdt)t(eK)t(eK)t(u DIp
Analog PID Implementation
[Ref] Kilian
Digital PID Control
Digital
Analog
Tarek A. Tutunji
Digital PID Realization
Required Operations: •Multiplication •Addition •Delay
Discrete PID Implementation
Digital Control Block Diagram
Intelligent Control
Dr. Tarek A. Tutunji
Intelligent controllers are used for high-level control
Intelligent controllers are also used when the system must make decisions (from several alternatives) based on input data from sensors.
Intelligent Control is usually used when the mathematical model for the plant is unavailable or highly complex.
The most two commonly used intelligent controllers are
Artificial Neural Networks
Fuzzy Logic
Intelligent Controllers Applications
[Ref] Tunstel
Intelligent Controller Application
•Low Level PID Control for velocity control •High Level Intelligent Control:
•Fuzzy for Decision making •Neural nets for Image Analysis
D R . T A R E K T U T U N J I
Hardware Controllers
Analog vs. Digital Control Systems
Analog Digital
Time variable Continuous Discrete
Time equations Differential equations Difference equations
Frequency transforms Laplace Z-Transform
Stability Poles on LHS Poles inside unit circle
Controller Hardware: Op-Amps Software: None
Hardware: Microcontroller Software: Program
Dr. Tarek A. Tutunji
Criteria for Choosing Controller
Price Size and Weight Number of Digital Inputs and Outputs Number of Analog Inputs and Outputs Speed Required Interrupt Required hardware Communication Interface Reliability Memory Programming Capability Software Support
Dr. Tarek A. Tutunji
Hardware Controllers
Microcontroller
PLCs
DSPs
PC with DAQ
Dr. Tarek A. Tutunji
Microcontrollers
Microcontroller is a special type of small computer that can perform a specific job
Microcontrollers
The microcontroller is a computer-on-chip. It is an integrated circuit that contains microprocessor, memory, I/O ports and sometimes A/D converters. It can be programmed using several languages (such as Assembly or C/C++). It can be used in manufacturing lines, but requires additional hardware. Microcontrollers are mainly used in engineering products such as washing machines and air-conditioners.
Dr. Tarek A. Tutunji
Microcontrollers Companies
Microcontroller Market Share
PIC16F84
PIC16F877
Arduino
Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software.
The hardware consists of a simple open source hardware board designed around an 8-bit Atmel AVR microcontroller, though a new model has been designed around a 32-bit Atmel ARM
Arduino Uno
Arduino Uno
UNO vs. MEGA
PLCs
A Programmable Logic Controller (or PLC) is a specialized digital controller that can control machines and processes. it monitors inputs, makes decisions, and controls outputs in order to automate machines and processes
Programmable Logic Controller
PLC’s are a user-friendly, microprocessor-based, specialized computer that is used for process control. It contains input/output (I/O) modules for appropriate sensors/actuator interfaces. It is mainly used in automated manufacturing lines. The PLC is usually used for simple logic operations. It is considered reliable and easy to program (using ladder diagrams, instructions, or function blocks).
Dr. Tarek A. Tutunji
PLC Manufacturers
PLC vs. Microcontroller
Usually PLCs are used in an industrial environment, where as the microcontrollers are smaller and well suited for embedded situations.
PLCs are programmed with ready made blocks or programming elements, whereas in Microcontrollers a programming language must be used to write a programming code
PLC Advantages
They are highly reliable, fast and flexible.
They can handle severe conditions such as dust, humidity etc.
They can communicate with other controllers.
They are easy to program and troubleshoot.
They include display units.
Digital Signal Processors
Digital Signal Processing (DSP) is the arithmetic processing of discrete-time signals. A/D is needed for analog signals
Digital signal processors (DSP) are specialized
microprocessors with advanced architectures (such as multiple buses, parallel processing, hardware multipliers and fast sampling rate) that are designed to reduce the number of instructions and operations necessary for efficient processing.
DSP chips enable developers to implement complex
algorithms and perform computationally efficient and fast algorithms. DSP are preferred over microcontrollers when the need for complex and
iterative control algorithms is required.
Dr. Tarek A. Tutunji
Digital Signal Controllers Manufacturers
Texas Instruments.
TMS320C2000™ DSP Platform
Microchip.
dsPIC30F3010
Motorola
Custom made DSP Engines
Personal Computers
Personal computers are used when extensive signal processing and in-depth analysis is required.
This will require Data Acquisition Cards (DAQs) to interface
the I/O power and signals between the PC and the environment.
Advantages include superior graphical and software
flexibility. However, the cost is high and, therefore, they are not suitable
for a large number of products Another disadvantage is the speed
Dr. Tarek A. Tutunji
PCs and DAQs
Summary
The selection of the controller is arguably the most important issue of the mecahtronics system
This choice can be divided into two parts:
1. Software/Firmware algorithm On-Off, PID, Adaptive, Robust, Optimal, and Intelligent
2. Hardware system Microcontroller, PLC, DSP, FPGA, and PC-DAQ
Dr. Tarek A. Tutunji
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