DESIGN OF USB BASED DATA ACQUISITION

SYSTEM AND IMPLEMENTATION OF DIGITAL

CONTROL ALGORITHMS

A PROJECT REPORT

Submitted by

DHARSHANA ,S. (20083213)

GOURAV SAHA (20083218)

JANAARTHANAN ,M. (20083223)

in partial fulfillment for the award of the degree

of

BACHELOR OF ENGINEERING

IN

ELECTRONICS AND INSTRUMENTATION ENGINEERING

MADRAS INSTITUTE OF TECHNOLOGY CAMPUS

ANNA UNIVERSITY : CHENNAI 600 044

APRIL 2012

DESIGN OF USB BASED DATA ACQUISITION

SYSTEM AND IMPLEMENTATION OF DIGITAL

CONTROL ALGORITHMS

A PROJECT REPORT

Submitted by

DHARSHANA ,S. (20083213)

GOURAV SAHA (20083218)

JANAARTHANAN ,M. (20083223)

in partial fulfillment for the award of the degree

of

BACHELOR OF ENGINEERING

IN

ELECTRONICS AND INSTRUMENTATION ENGINEERING

MADRAS INSTITUTE OF TECHNOLOGY CAMPUS

ANNA UNIVERSITY : CHENNAI 600 044

APRIL 2012

ANNA UNIVERSITY : CHENNAI 600 044

BONAFIDE CERTIFICATE

Certified that this project titled ‘DESIGN OF USB BASED DATA

ACQUISITION SYSTEM AND IMPLEMENTATION OF DIGITAL

CONTROL ALGORITHMS’, is the bonafide work of

DHARSHANA ,S. (20083213)

GOURAV SAHA (20083218)

JANAARTHANAN ,M. (20083223)

who carried out the project work under my supervision. Certified further, that to

the best of my knowledge the work reported herein does not form part of any

project on the basis of which a degree or award was conferred on an earlier

occasion on this or any other candidate.

Dr.K.BHOOPATHY BAGAN Dr.J.PRAKASH

Professor and Head, Associate Professor,

Department of Instrumentation Engg, Department of Instrumentation Engg,

MIT campus, MIT Campus,

Anna University, Anna University,

Chennai – 600 044 Chennai – 600 044

i

ACKNOWLEDGEMENT

We would take immense pleasure in thanking Dr. S. Thamarai Selvi,

Dean, Madras Institute of Technology, for providing us all the facilities.

We would like to express our grateful thanks to Dr. K. Bhoopathy

Bagan, Professor and Head, Department of Instrumentation Engineering,

Madras Institute of Technology, for being an inspiration to us and for his

encouragement during the course of the project.

We are indebted to Dr.J.Prakash, Associate Professor, for his excellent

guidance and continuous encouragement throughout this project work. His

friendly guidance and expert advice were invaluable throughout this work. We

wish to express our deep sense of gratitude for him.

We would also like to thank Mrs. Sabitha Ramakrishnan, Dr. N.

Pappa, and Mr.Raman for giving us valuable suggestions.

Also, we would like to thank all the staff members of the Department of

Instrumentation Engineering, who had helped us during the course of this

project work.

ii

ABSTRACT

In this project, our main objective is to design an USB data

acquisition module and program it to receive inputs from a system which is then

controlled by the conventional and advanced control algorithms implemented in

a personal computer. This project is an integration of the following modules:

Analog to digital convertor

Digital to analog convertor

Power delivering circuitry

Interfacing algorithms

Control algorithms coded in Matlab

Online control of a process using the algorithms in PC

The process that is selected for control is a first order RC process which is

realized using analog circuit components. The following are the algorithms that

have been implemented:

System identification using Linear Least Square Algorithm

Proportional- Integral control

Auto-tuning Proportional- Integral control

Model Reference Adaptive Control

Synthesis method of controller design

iii

LIST OF FIGURES

FIG.

NO

NAME PAGE

NO.

1.1 BASIC BLOCK DIAGRAM OF THE PROJECT 5

2.1 PIN CONFIGURATION OF LM79XX SERIES 6

2.2 PIN CONFIGURATION OF LM78XX SERIES 6

2.3 TYPICAL CONNECTION FOR POWER SUPPLY CIRCUIT 7

2.4 PIN CONFIGURATION OF ADC 0804 8

2.5 TYPICAL CONNECTIONS BETWEEN ADC 0804 AND

MICROCONTROLLER

9

2.6 PIN CONFIGURATION OF DAC 0808 9

2.7 TYPICAL CONNECTION FOR DAC 0808 10

2.8 PIN CONFIGURATION OF ATMega328

MICROCONTROLLER

11

2.9 PIN CONFIGURATION OF CD4051 ANALOG

MULTIPLEXER

14

2.10 PIN CONFIGURATION OF MAX 232 15

2.11 TYPICAL CONNECTION FOR SERIAL LEVEL

CONVERTOR CIRCUIT

16

2.12 PROLIFIC USB TO SERIAL CONVERTER 17

2.13 ARDUINO UNO 18

2.14 INTEGRATED HARDWARE 19

4.1 BLOCK DIAGRAM OF MRAC SYSTEM 46

5.1 GRAPH FOR SYSTEM IDENTIFICATION ALGORITHM 49

5.2 SERVO RESPONSE OF FIRST ORDER SYSTEM WITH PI

CONTROLLER

50

5.3 SERVO RESPONSE OF FIRST ORDER SYSTEM WITH

AUTOTUNED PI CONTROLLER

51

iv

5.4 SERVO RESPONSE OF FIRST ORDER SYSTEM WITH

MODEL REFERNCE ADAPTIVE CONTROLLER

52

5.5 SERVO RESPONSE OF FIRST ORDER SYSTEM WITH

SYNTHESISED CONTROLLER

53

1

TABLE OF CONTENTS

CHAPTER NO. TITLE PAGE NO.

ABSTRACT ii

LIST OF FIGURES iii

1. INTRODUCTION

1.1 DATA ACQUISITION SYSTEM 3

1.2 WHY USB? 4

1.3 DIGITAL/DISCRETE CONTROL SYSTEMS 5

2. DAQ HARDWARE

2.1 HARDWARE USED

2.1.1 VOLTAGE REGULATOR 6

(LM79xx & LM78xx series)

2.1.2 ADC0804 8

2.1.3 DAC0808 9

2.1.4 ATMega328 MICROCONTROLLER 11

2.1.5 CD4051 ANALOG MULTIPLEXER 14

2.1.6 MAX232 15

2.1.7 PROLIFIC USB TO SERIAL CONVERTER 17

2.1.8 ARDUINO UNO 18

2.1.9 INTEGRATED HARDWARE 19

3. SOFTWARE

3.1 INTERFACING WITH C

3.1.1 MICROCONTROLLER CODE 20

3.1.2 PC CODE (WRITTEN IN C) 26

2

3.2 INTERFACING WITH MATLAB

3.2.1 MICRCONTROLLER CODE 29

3.2.2 PC CODE (WRITTEN IN MATLAB) 35

4. DIGITAL CONTROL ALGORITHMS

4.1 SYSTEM IDENTIFICATION: LINEAR LEAST 38

SQUARE ALGORITHM

4.2 PI CONTROLLER 41

4.3 AUTOTUNED PI CONTROLLER 42

4.4 CONTROLLER DESIGNED USING SYNTHESIS 44

METHOD

4.5 MODEL REFRENCE ADAPTIVE CONTROLLER 46

5. RESULTS AND DISCUSSION

5.1 SERVO RESPONSE OF FIRST ORDER SYSTEM FOR:

5.1.1 SYSTEM IDENTIFICATION: LINEAR 48

LEAST SQUARE ALGORITHM

5.1.2 PI CONTROLLER 49

5.1.3 AUTOTUNED PI CONTROLLER 49

5.1.4 CONTROLLER DESIGNED USING 50

SYNTHESIS METHOD

5.1.5 MODEL REFRENCE ADAPTIVE 51

CONTROLLER

6. CONCLUSION 52

7. REFERENCES 53

3

CHAPTER 1

INTRODUCTION

1.1 DATA ACQUISITION SYSTEM

Data acquisition is the process of sampling signals that measure real world

physical conditions and converting the resulting samples into digital numeric values

that can be manipulated by a computer. Data acquisition systems (abbreviated with the

acronym DAS or DAQ) typically convert analog waveforms into digital values for

processing. DAQ systems also employ various signal conditioning techniques to

adequately modify acquired electrical signals into voltage that can then be digitized

using an Analog-to-digital converter (ADC).

DAQ hardware is what usually interfaces between the signal and a PC. It could

be in the form of modules that can be connected to the computer's ports

(parallel, serial, USB, etc.) or cards connected to slots (S-100 bus, AppleBus,

ISA, MCA, PCI, PCI-E, etc.) in the motherboard. The fixed connection with the PC

allows for comfortable compilation and debugging. Not all DAQ hardware has to run

permanently connected to a PC, for example intelligent stand-alone loggers and

oscilloscopes, which can be operated from a PC, yet they can operate completely

independent of the PC. In this project, USB port is used for communication with the

PC.

DAQ software is needed in order for the DAQ hardware to work with a PC. The

device driver performs low-level register writes and reads on the hardware. Data

acquisition applications are controlled by software programs developed using various

general purpose programming languages such as BASIC , C, Fortran , Java , Lisp,

Pascal.

4

1.2 WHY USB?

Universal Serial Bus (USB) is an industry standard developed in the mid-1990s

that defines the cables, connectors and communications protocols used in a bus for

connection, communication and power supply between computers and electronic

devices.

USB was designed to standardize the connection of computer peripherals, such

as keyboards, pointing devices, digital cameras, printers, portable media players, disk

drives and network adapters to personal computers, both, to communicate and to

supply electric power. USB has effectively replaced a variety of earlier interfaces,

such as serial and parallel ports, as well as separate power chargers for portable

devices. As of 2008, approximately 6 billion USB ports and interfaces are currently in

the global marketplace, and about 2 billion were being sold each year.

The popularity of USB is mainly due to its ease of device detection that occurs

automatically once the device is plugged-in. It is fondly referred to as a “ Hot spot

port ” since it enables easy plug-in and plug- out of portable computer accessories.

Unlike the other device ports, the USB port does not require explicit and intensive

programming to detect each device. Finally, owing to the growing speed technology

of the USB port, it tops the other methods of interfacing a portable device with PC.

Hence USB port is chosen as the communication means for the Data Acquisition

System designed as a part of this project.

1.3. DIGITAL / DISCRETE CONTROL SYSTEMS:

Computer-controlled digital systems can be controlled by software, allowing

new functions to be added without changing hardware. For instance, changing the

proportional gain for digital system can be done just by changing the program in the

computer, whereas in an analog system it would require changes done in the design

5

from the scratch. Also, running the controller algorithms on a computer facilitate

much faster execution rather than embedding it in a microcontroller. The memory in

microcontroller will not be sufficient to run complex programs like neural control

programs. Hence, in this project we have chosen to interface the microcontroller with

the computer where the control programs will actually be run.

Further more, signals represented digitally can be transmitted without

degradation due to noise. For example, a continuous audio signal, transmitted as a

sequence of 1s and 0s, can be reconstructed without error provided the noise picked

up in transmission is not enough to prevent identification of the 1s and 0s.

Information storage can be easier in digital systems than in analog ones. The

noise-immunity of digital systems permits data to be stored and retrieved without

degradation. In an analog system, noise from aging and wear degrade the information

stored. In a digital system, as long as the total noise is below a certain level, the

information can be recovered perfectly.

1.1. BASIC BLOCK DIAGRAM OF THE PROJECT

6

CHAPTER 2

DAQ HARDWARE

2.1 HARDWARES USED

2.1.1 VOLTAGE REGULATOR (LM79xx & LM78xx series)

2.1 PIN CONFIGURATION OF LM79XX SERIES

2.2 PIN CONFIGURATION OF LM78XX SERIES

The 78xx (sometimes LM78xx) is a family of self-contained fixed linear

voltage regulator integrated circuits. The 78xx family is commonly used in electronic

circuits requiring a regulated power supply due to their ease-of-use and low cost. For

ICs within the family, the xx is replaced with two digits, indicating the

outputvoltage (for example, the 7805 has a 5 volt output, while the 7812 produces

7

12 volts). The 78xx line are positive voltage regulators: they produce a voltage that is

positive relative to a common ground. There is a related line of 79xx devices which

are complementary negative voltage regulators. 78xx and 79xx ICs can be used in

combination to provide positive and negative supply voltages in the same circuit.

Typical connections for the power supply circuit are shown in Fig.2.3.

2.3 TYPICAL CONNECTION FOR POWER SUPPLY CIRCUIT

COMPONENTS USED IN THE POWER SUPPLY CIRCUIT

• 18-0-18 centre tap transformer

• Rectifier bridge with 1N4007 diodes

• IC 7805, IC 7812, IC 7815

• IC 7905, IC 7912, IC 7915

• 1N4007 diodes used as current limiting diode across each of the 79XX ICs

• 2200 µF 50V capacitors

• 100 µF 63 V capacitors

The above circuit provides +15 V,-15 V, +12 V, -12 V, +5 V, -5 V.

8

2.1.2 ADC 0804

2.4 PIN CONFIGURATION OF ADC 0804

Features

• Compatible with 8080 Microprocessors and commonly used Microcontrollers.

• Easy interface to all microprocessors, or operates 'stand alone'

• Differential analog voltage inputs

• Logic inputs and outputs meet both MOS and TTL voltage level specifications

• Works with 2.5V (LM336) Voltage Reference

• On-chip clock generator

• 0V to 5V analog input voltage range with single 5V supply

• No zero adjust required

• Operates ratiometrically or with 5 Vdc, 2.5Vdc, or analog span adjusted voltage

Reference

Typical connections between microcontroller and ADC are portrayed in Fig.2.5.

9

2.5 TYPICAL CONNECTIONS BETWEEN ADC 0804 AND

MICROCONTROLLER

2.1.3 DAC 0808

2.6 PIN CONFIGURATION OF DAC 0808

10

Features

• Relative Accuracy: ±0.19% error maximum

• Full scale current match: ±1 LSB typical

• Fast Settling Time: 150 ns typical

• Non inverting digital inputs are TTL and CMOS compatible

• High speed multiplying input slew rate: 8 mA/µs

• Power Supply Voltage Range: ±4.5V to ±18V

• Low power consumption: 33 mW @ ±5V

Typical connections for the operation of DAC 0808 are shown in Fig.2.7.

2.7 TYPICAL CONNECTION FOR DAC 0808

11

2.1. 4 ATMega328 MICROCONTROLLER

2.8 PIN CONFIGURATION OF ATMega328 MICROCONTROLLER

Features

• Peripheral Features

– Two 8-bit Timer/Counters with Separate Prescaler and Compare Mode

– One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture

Mode

– Real Time Counter with Separate Oscillator

– Six PWM Channels

– 8-channel 10-bit ADC in TQFP and QFN/MLF package

Temperature Measurement

– 6-channel 10-bit ADC in PDIP Package

Temperature Measurement

12

– Programmable Serial USART

– Master/Slave SPI Serial Interface

– Byte-oriented 2-wire Serial Interface

– Programmable Watchdog Timer with Separate On-chip Oscillator

– On-chip Analog Comparator

– Interrupt and Wake-up on Pin Change

• Special Microcontroller Features

– Power-on Reset and Programmable Brown-out Detection

– Internal Calibrated Oscillator

– External and Internal Interrupt Sources

– Six Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, Standby,

and Extended Standby

• I/O and Packages

– 23 Programmable I/O Lines

– 28-pin PDIP, 32-lead TQFP, 28-pad QFN/MLF and 32-pad QFN/MLF

PIN DESCRIPTION

1- VCC

Digital supply voltage.

2- GND

Ground.

3- Port B (PB7:0) XTAL1/XTAL2/TOSC1/TOSC2

Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for

each bit). The Port B output buffers have symmetrical drive characteristics with both

high sink and source capability. As inputs, Port B pins that are externally pulled low

will source current if the pull-up resistors are activated. The Port B pins are tri-stated

when a reset condition becomes active, even if the clock is not running.

13

Depending on the clock selection fuse settings, PB6 can be used as input to the

inverting Oscillator amplifier and input to the internal clock operating circuit.

Depending on the clock selection fuse settings, PB7 can be used as output from the

inverting Oscillator amplifier.

4- Port C (PC5:0)

Port C is a 7-bit bi-directional I/O port with internal pull-up resistors (selected for

each bit). The PC5...0 output buffers have symmetrical drive characteristics with both

high sink and source capability. As inputs, Port C pins that are externally pulled low

will source current if the pull-up resistors are activated. The Port C pins are tri-stated

when a reset condition becomes active, even if the clock is not running.

5- PC6/RESET

If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin. Note that the

electrical characteristics of PC6 differ from those of the other pins of Port C.

If the RSTDISBL Fuse is unprogrammed, PC6 is used as a Reset input. A low level

on this pin for longer than the minimum pulse length will generate a Reset, even if the

clock is not running. Shorter pulses are not guaranteed to generate a Reset.

6- Port D (PD7:0)

Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for

each bit). The Port D output buffers have symmetrical drive characteristics with both

high sink and source capability. As inputs, Port D pins that are externally pulled low

will source current if the pull-up resistors are activated. The Port D pins are tri-stated

when a reset condition becomes active, even if the clock is not running.

7- AVCC

AVCC is the supply voltage pin for the A/D Converter, PC3:0, and ADC7:6. It should

be externally connected to VCC, even if the ADC is not used. If the ADC is used, it

should be connected to VCC through a low-pass filter. Note that PC6...4 use digital

supply voltage, VCC

14

8- AREF

AREF is the analog reference pin for the A/D Converter.

9- ADC7:6 (TQFP and QFN/MLF Package Only)

In the TQFP and QFN/MLF package, ADC7:6 serve as analog inputs to the A/D

converter. These pins are powered from the analog supply and serve as 10-bit ADC

channels.

2.1.5 CD4051 ANALOG MULTIPLEXER

2.9 PIN CONFIGURATION OF CD4051 ANALOG MULTIPLEXER

These analog multiplexers are digitally controlled analog switches having low

``ON'' impedance and very low ``OFF'' leakage currents. Control of analog signals up

to 15Vp-p can be achieved by digital signal amplitudes of 3±15V. For example, if

VDD 5V, VSS 0V and VEE 5V, analog signals from 5V to 5V can be controlled by

digital inputs of 0±5V. The multiplexer circuits dissipate extremely low quiescent

power over the full VDD VSS and VDD VEE supply voltage ranges, independent of

the logic state of the control signals. When a logical ``1'' is present at the inhibit input

terminal all channels are ``OFF''. CD4051BM/CD4051BC is a single 8-channel

15

multiplexer having three binary control inputs. A, B, and C, and an inhibit input. The

three binary signals select 1 of 8 channels to be turned ``ON'' and connect the input to

the output.

2.1.6 MAX232

2.10 PIN CONFIGURATION OF MAX 232

The MAX232 IC is used to convert the TTL/CMOS logic levels to RS232

logic levels during serial communication of microcontrollers with PC. The controller

operates at TTL logic level (0-5V) whereas the serial communication in PC works on

RS232 standards (-25 V to + 25V). This makes it difficult to establish a direct link

between them to communicate with each other.

The intermediate link is provided through MAX232. It is a dual driver/receiver

that includes a capacitive voltage generator to supply RS232 voltage levels from a

single 5V supply. Each receiver converts RS232 inputs to 5V TTL/CMOS levels.

These receivers (R1 & R2) can accept ±30V inputs. The drivers (T1 & T2), also called

transmitters, convert the TTL/CMOS input level into RS232 level.

16

The transmitters take input from controller’s serial transmission pin and send

the output to RS232’s receiver. The receivers, on the other hand, take input from

transmission pin of RS232 serial port and give serial output to microcontroller’s

receiver pin. MAX232 needs four external capacitors whose value ranges from 1µF to

22µF. Typical connections for constructing the serial level convertor circuit are given

in Fig.2.11.

2.11 TYPICAL CONNECTION FOR SERIAL LEVEL CONVERTOR

CIRCUIT

In computing, a serial port is a serial communication physical interface through

which information transfers in or out one bit at a time. Throughout most of the history

of personal computers, data transfer through serial ports connected the computer to

devices such as terminals and various peripherals.

MAX232: As we know for serial port we require TIA/EIA-232-F voltage level i.e.

it can accept ±30-V. MAX232 has a capacitive voltage generator to supply TIA/EIA-

232-F voltage levels from a single 5-V supply. Each receiver converts TIA/EIA-232-F

inputs to 5-V TTL/CMOS levels.

17

So, to interface the atmega32 to the computer we will be connecting atmega32 (pin

no 14 & 15) to serial port via max232. We are using max232 because atmega32 works

at TTL voltage level and for serial port we require other voltage level, max232

converts the TTL voltage level to the required voltage level.

Atmega32 will receive the signal from MAX232 and transmit to max232 which

will be received by serial port. The following connections were done:

• pin no 2 (Tx) of serial port to Tx out of the MAX 232 IC (pin no 14)

• pin no 3 (Rx) of serial port to Rx in of the MAX 232 IC (pin no 13)

• pin no 14 (RxD) of Atmega to Rx out of MAX 232 IC (pin no 12)

• pin no 15 (TxD) of Atmega to Tx in of MAX 232 IC (pin no 11)

2.1.7 PROLIFIC USB TO SERIAL CONVERTER

2.12 PROLIFIC USB TO SERIAL CONVERTER

The Beagle Software USB to serial adapter allows you to use serial hardware with

your USB-equipped laptop or desktop computer.The USB to serial adapter connects

RS-232 serial devices to your USB-equipped Windows computer, providing a bridge

18

connection with a standard DB 9-pin male serial port connector on one end and a

standard USB plug connector on the other. You simply attach your serial device to the

DB 9-pin end of the adapter cable and plug the USB connector into your PC's USB

port.

Features

• Adds a COM port to USB PC allowing usage of legacy serial devices on the

PC

• Can be used with modems, PDAs (including Palm), cellular phones, GPSs,

digital cameras, card readers, and more

• Supports Beagle Software's serial devices including DocuClock printers, Star

Sync and Cell Sync receivers

• Easy plug-and-play installation

• USB-powered—no separate power supply or battery required

• Easily fits into laptop cases for on-the-go applications

2.1.8 ARDUINO UNO

2.13 ARDUINO UNO

19

The Arduino Uno is a microcontroller board based on

the ATmega328 (datasheet). It has 14 digital input/output pins (of which 6 can be used

as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a

power jack, an ICSP header, and a reset button. It contains everything needed to

support the microcontroller; simply connect it to a computer with a USB cable or

power it with a AC-to-DC adapter or battery to get started.

2.1.9 INTEGRATED HARDWARE

2.14 INTEGRATED HARDWARE

20

CHAPTER 3

SOFTWARE

3.1 INTERFACING WITH C

3.1.1 MICROCONTROLLER CODE

The baud rate of communication is set as 9600 bps in the function setup(). The

function loop() polls itself continously. Inside the function loop() the value of choice

can be either -1, 0 or 1. If the value of choice is -1 then it listens to the serial port for

the command "RD" or "WT". If the command received is "RD" choice is set to 0 and

1 if command received is "WT". If choice is set to 0 then the micrcontroller reads the

input analog volatge using ADC0804 and saves the result in the variable value. The

value is then serially transmitted to the computer. After this, the serial buffer is

flushed and choice is again set to -1. Likewise, if the choice is set as 1 then the

microcontroller has to perform a write operation. So, it first listens to the serial port

for the analog voltage which it has to set using the DAC0808. It saves this voltage as

value. The value is then converted into its digital equivalent and sent to the DAC0808.

The serial buffer is then flushed and choice is set to -1.

Given below is the code burnt into the microcontroller.

int i, k, choice, ch;

char cmnd[2];

void setup()

{

Serial.begin(9600);

Serial.flush();

for (i=2; i<=13; i=i+1)

{

pinMode(i, OUTPUT);

21

}

k=0;

choice=-1;

}

void loop()

{

if (choice==0)

{

int value=0, b;

digitalWrite(2, LOW);

delay(2);

digitalWrite(2, HIGH);

delay(2);

digitalWrite(4, LOW);

digitalWrite(3, LOW);

digitalWrite(13, LOW);

delay(1);

b=analogRead(5);

if (b>200)

{

value=value+1;

}

digitalWrite(4, LOW);

digitalWrite(3, LOW);

digitalWrite(13, HIGH);

delay(1);

b=analogRead(5);

22

if (b>200)

{

value=value+2;

}

digitalWrite(4, LOW);

digitalWrite(3, HIGH);

digitalWrite(13, LOW);

delay(1);

b=analogRead(5);

if (b>200)

{

value=value+4;

}

digitalWrite(4, LOW);

digitalWrite(3, HIGH);

digitalWrite(13, HIGH);

delay(1);

b=analogRead(5);

if (b>200)

{

value=value+8;

}

digitalWrite(4, HIGH);

digitalWrite(3, LOW);

digitalWrite(13, LOW);

delay(1);

b=analogRead(5);

23

if (b>200)

{

value=value+16;

}

digitalWrite(4, HIGH);

digitalWrite(3, LOW);

digitalWrite(13, HIGH);

delay(1);

b=analogRead(5);

if (b>200)

{

value=value+32;

}

digitalWrite(4, HIGH);

digitalWrite(3, HIGH);

digitalWrite(13, LOW);

delay(1);

b=analogRead(5);

if (b>200)

{

value=value+64;

}

digitalWrite(4, HIGH);

digitalWrite(3, HIGH);

digitalWrite(13, HIGH);

delay(1);

b=analogRead(5);

24

if (b>200)

{

value=value+128;

}

Serial.write(value);

choice=-1;

Serial.flush();

}

else

if (choice==1)

{

int value=0, f=1;

do

{

if (Serial.available()>0)

{

ch=Serial.read();

value=ch;

f=0;

}

}

while (f==1);

for (i=0; i<=7; i=i+1)

{

if (i>=0 && i<=3)

{

digitalWrite((12-i), bitRead(value, i));

25

}

else

if (i>=4 && i<=7)

{

digitalWrite((1+i), bitRead(value, i));

}

}

choice=-1;

Serial.flush();

}

else

if (choice==-1)

{

if (Serial.available()>0)

{

ch=Serial.read();

if (ch>=int('A') && ch<=int('Z'))

{

cmnd[k]=char(ch);

k=k+1;

}

if (k==2)

{

if (cmnd[0]=='R' && cmnd[1]=='D')

{

choice=0;

}

26

else

if (cmnd[0]=='W' && cmnd[1]=='T')

{

choice=1;

}

k=0;

}

}

}

}

3.1.2 PC CODE (WRITTEN IN C)

In the function setport() the parameter of the serial communication is set, i.e.-

baud rate, parity bits, stop bits and the data word length. For or program baud rate is

9600 bps, no parity bits, one stop bit and data word length of 8.COM PORT 2 (0x2F8

is the base address of the COM PORT 2) is used for this purpose .When the function

read() is called, it sends the command to the "RD" to COM PORT 2 using the

function outportb(). This will instruct the microcontroller to perform read operation.

After that it waits for the microcontroller to send the analog input voltage. When the

microcontroller send the data, it is read using the function inportb(). When the

function write() is called, it sends the command to the "WT" to COM PORT 2 using

the function outportb(). This will instruct the microcontroller to perform write

operation. After this it sends the analog value the microcontroller has to output using

the outportb() function.

Given below is the code running on the PC.

#include<dos.h>

#include<stdio.h>

27

#include<conio.h>

#define PORT 0x2F8

double REF_ADC=5.0, REF_DAC=5.0;

double read()

{

int value, flag, c, ch, k;

double val;

char cmnd[2];

cmnd[0]='R';

cmnd[1]='D';

for (k=0; k<2; k++)

{

delay(1);

outportb(PORT, int(cmnd[k]));

}

value=0;

flag=1;

while (flag)

{

c=inportb(PORT + 5);

if (c & 1)

{

ch=inportb(PORT);

value=ch;

flag=0;

}

}

28

val=(REF_ADC*value)/255.0;

return val;

}

void write(double val)

{

int k, value;

int arr[4], cmnd[4];

cmnd[0]=int('W');

cmnd[1]=int('T');

for (k=0; k<2; k++)

{

delay(1);

outportb(PORT, cmnd[k]);

}

value=int((255.0*val)/REF_DAC);

if (value>255)

value=255;

else

if (value<0)

value=0;

outportb(PORT, value);

}

void setport()

{

outportb(PORT + 1 , 0);

outportb(PORT + 3 , 0x80);

outportb(PORT + 0 , 0x0C);

29

outportb(PORT + 1 , 0x00);

outportb(PORT + 3 , 0x03);

outportb(PORT + 2 , 0xC7);

outportb(PORT + 4 , 0x0B);

}

3.2 INTERFACING WITH MATLAB

3.2.1 MICRCONTROLLER CODE

This code basically implements a state machine that reads the serial port

and makes just one transition to a new state, depending on both the previous state and

the command that is read from the serial port. Some commands need additional inputs

from the serial port, so they need 2 transitions (each one happening as soon as

anything new is available from the serial port) to be fully executed. After a command

is fully executed the state returns to its initial value s=-1. When state s=-1 it listens to

the serial port for any available data. If the incoming data from serial port is 51 then

the state s is set as 30, if it is 52 then s=40 and if it is 57 then s=90. If state s=30 read

operation has to be performed and microcontroller request the ADC0804 for the

analog input. After receiving the analog input from ADC0804 it is sent serially to the

computer. If s=40 then the write operartion has to be performed. The microcontroller

will listen to the serial port for the analog value it has to output and accordingly set the

DAC0808. State s=90 is basically used by MATLAB to know if the DAQ is actually

connected to the computer. So when state s=90 is invoked the microcontroller send

the number 1 to MATLAB to acknowledge its presence.

Given below is the code burnt in microcontroller for interfacing with

MATLAB.

30

void setup()

{

int i;

for (i=2;i<13;i++)

{

pinMode(i,OUTPUT);

}

Serial.begin(9600);

}

void loop()

{

int s = -1;

int pin = 3;

int val = 0;

int agv = 0;

if (Serial.available()>0)

{

val = Serial.read();

switch (s)

{

case -1:

if (val>47 && val<90)

{

s=10*(val-48);

}

if ((s>40 && s<90) || (s>90 && s!=340))

{

31

s=-1;

}

break;

case 30:

if (val>96 && val<103)

{

int value=0, b;

digitalWrite(2, LOW);

delay(2);

digitalWrite(2, HIGH);

delay(2);

digitalWrite(4, LOW);

digitalWrite(3, LOW);

digitalWrite(13, LOW);

delay(1);

b=analogRead(5);

if (b>200)

{

value=value+1;

}

digitalWrite(4, LOW);

digitalWrite(3, LOW);

digitalWrite(13, HIGH);

delay(1);

b=analogRead(5);

if (b>200)

{

32

value=value+2;

}

digitalWrite(4, LOW);

digitalWrite(3, HIGH);

digitalWrite(13, LOW);

delay(1);

b=analogRead(5);

if (b>200)

{

value=value+4;

}

digitalWrite(4, LOW);

digitalWrite(3, HIGH);

digitalWrite(13, HIGH);

delay(1);

b=analogRead(5);

if (b>200)

{

value=value+8;

}

digitalWrite(4, HIGH);

digitalWrite(3, LOW);

digitalWrite(13, LOW);

delay(1);

b=analogRead(5);

if (b>200)

{

33

value=value+16;

}

digitalWrite(4, HIGH);

digitalWrite(3, LOW);

digitalWrite(13, HIGH);

delay(1);

b=analogRead(5);

if (b>200)

{

value=value+32;

}

digitalWrite(4, HIGH);

digitalWrite(3, HIGH);

digitalWrite(13, LOW);

delay(1);

b=analogRead(5);

if (b>200)

{

value=value+64;

}

digitalWrite(4, HIGH);

digitalWrite(3, HIGH);

digitalWrite(13, HIGH);

delay(1);

b=analogRead(5);

if (b>200)

{

34

value=value+128;

}

Serial.println(value);

}

s=-1;

break;

case 40:

if (val>98 && val<117)

{

pin=val-97;

s=41;

}

else

{

s=-1;

}

break;

case 41:

{

for (i=0; i<=7; i=i+1)

{

if (i>=0 && i<=3)

{

digitalWrite((12-i), bitRead(val, i));

}

else

if (i>=4 && i<=7)

35

{

digitalWrite((1+i), bitRead(val, i));

}

}

s=-1;

break;

case 90:

if (val==57)

{

Serial.println(1);

}

s=-1;

break;

default:

s=-1;

}

}

}

3.2.2 PC CODE (WRITTEN IN MATLAB)

This code is implemented in MATLAB. It basically creates a class mydaq

which has all the function to operate on the DAQ, for e.g. initialization (constructor

function), deletion (destructor function), reading (read function) and writing(write

function). When the constructor function is called it first sets the baud rate of the

desired COM PORT as 9600 bps. After that it tries to communicate with the DAQ.

Only if the DAQ communicates back will it create an object of its type. The funcion

read() and write() is to perform reading and writting operation. The function fwrite() is

36

used to send data serially while the function fscanf() is used to read data which is

coming from the serial port.

Given below is the code written in PC for interfacing the microcontroller with

MATLAB.

classdef mydaq < handle

properties (SetAccess=private,GetAccess=private)

aser

end

methods

function a=mydaq(comPort)

a.aser=serial(comPort,'BaudRate',9600);

try

fopen(a.aser);

catch ME,

delete(a);

error(['Could not open port: ' comPort]);

end

fprintf(1,'Attempting connection .');

for i=1:7,

fprintf(1,'.');

pause(1);

end

fprintf(1,'\n');

fwrite(a.aser,[57 57],'uchar');

chk=fscanf(a.aser,'%d');

if isempty(chk)

delete(a);

37

error('Connection unsuccessful, please make sure that the Daq is powered

on, running the server program, and that the board is connected to the indicated

serial port.');

end

if chk==1

disp('DAQ READY');

end

end

function delete(a)

if isa(a.aser,'serial') && isvalid(a.aser) &&

strcmpi(get(a.aser,'Status'),'open'),

fclose(a.aser);

end

if isobject(a.aser),

delete(a.aser);

end

end

function val=read(a)

fwrite(a.aser,[51 97],'uchar');

val=fscanf(a.aser,'%d');

end

function write(a,val)

fwrite(a.aser,[52 100 val],'uchar');

end

end

end

38

CHAPTER 4

DIGITAL CONTROL ALGORITHMS

4.1 SYSTEM IDENTIFICATION: LINEAR LEAST SQUARE ALGORITHM

The system identification code employs an offline linear least square algorithm.

If the process is given by,

����� � �������� �

�� ���� ������ ������ ����� ������� ��

(1)

The formula for offline least square algorithm is:

� � �����-���� where,

� � ����������������������� !�"

#

�

$%%%%& ��'���' � ����' � ��

((

��' � )�

���

��' � ����'�

��' � ��((

��' � ) � ��

���

��' � ����' � ����'�((

��' � ) � ��

���

(((

(

���

(((

(

���

��' � ����' � � �����' � � ���(

(��' � ) ���

���

���' � �����'�

���' � ��((

���' � ) � ��

���

���' � �����' � �����'�((

���' � ) � ��

���

(((

(

���

(((

(

�����

�

* � ���'�����' � �������' � �����' � )�!

N is the number of samples.

The code first creates the matrix A and B. Then it performs the operation

described by offline least square algorithm.

The myident() function has the provision for getting both the discrete and

continous model of the process.

CODE:

function [model]=myident(u, y, n, m, del, type)

data=numel(u);

for i=1:1:data

39

for j=1:1:(n+1)

degree=n+1-j;

A(i,j)=0;

if ((i-degree)>=1)

A(i,j)=u(i-degree);

end

end

for j=(n+2):1:(n+m+1)

degree=n+m+2-j;

A(i,j)=0;

if ((i-degree)>=1)

A(i,j)=-1*y(i-degree);

end

end

B(i,1)=y(i);

end

C=transpose(A);

coeff=inv(C*A)*(C*B);

for k=1:1:(n+1)

NUM(k,1)=coeff((n+2-k),1);

end

for k=1:1:m

DENO(k,1)=coeff(n+m+2-k,1);

end

if (type=='D')

num=NUM;

deno=DENO;

40

model=tf(num, [1 deno], del, 'variable','z^-1');

elseif (type=='C')

for i=0:1:n

num(1+i)=0;

for j=i:1:n

num(1+i)=num(1+i)+NUM(1+j)*((j*del)^(i))/factorial(i);

end

if ((i-floor(i/2.0)*2.0)==1)

num(1+i)=num(1+i)*-1;

end

end

for i=1:1:m

deno(i)=0;

for j=i:1:m

deno(i)=deno(i)+DENO(j)*((j*del)^(i))/factorial(i);

end

if ((i-floor(i/2.0)*2.0)==1)

deno(i)=deno(i)*-1;

end

end

factor=1;

for j=1:1:m

factor=factor+DENO(j);

end

num=num/factor;

deno=deno/factor;

len=numel(num);

41

mid=floor(len/2);

for m=1:mid

copy=num(m);

num(m)=num(len+1-m);

num(len+1-m)=copy;

end

len=numel(deno);

mid=floor(len/2);

for m=1:mid

copy=deno(m);

deno(m)=deno(len+1-m);

deno(len+1-m)=copy;

end

model=tf(num,[deno 1]);

end

4.2 PI CONTROLLER

The algorithm implements a simple PI controller described by the following

formula:

��+� � *,�� � -./�+� � -0 1 /�2�324� (2)

The variable sumerror stores the value of the integral of past errors.

It has the provision for both direct and reverse action. For our process we have

set Kp=0.9 and Ki=0.4.

42

CODE:

function [OP sumerror]=myPI(Kp, Ki, Bias, SP, Y, del, sumerror, action)

y=5.0*Y/256.0;5

if (action=='D')

error=y-Sp;

elseif (action=='R')

error=SP-y;

end

op=Bias+Kp*error+Ki*sumerror;

OP=max(0,min(255,floor(255.0*op/5.0)));

sumerror=sumerror+error*del;

end

4.3 AUTOTUNED PI CONTROLLER

The autotuning PI code aims to tune the PI controller for a particular process in

such a way so as to reduce integral square error (ISE). The code first uses the

myident() function to make a model of the process. The model is then used to obtain

the unit step response of the process. The genetic algorithm function (ga()) of

MATLAB is then used to reduce the integral square error of the step response.

CODE:

function [Kp Ki]=myAutoPI(obj, Tf, del, nProcess, mProcess)

t=0:del:Tf;

N=Tf/del+1;

for i=1:1:floor(N/4);

u(i)=4;

43

end

for i=(floor(N/4)+1):1:floor(2*N/4);

u(i)=1;

end

for i=(floor(2*N/4)+1):1:floor(3*N/4);

u(i)=3;

end

for i=(floor(3*N/4)+1):1:N;

u(i)=2;

end

for i=1:1:N

Y=obj.read();

y(i)=5.0*Y/256.0;

U=floor(255.0*u(i)/5.0);

U=max(0,min(255,U));

obj.write(U);

pause(del);

end

obj.write(0);

Gp=myident(u,y,nProcess,mProcess,del,'C');

k=ga(@myise,2);

function [ise]=myise(Const)

Gc=tf(Const, [1 0]);

Gcl=Gc*Gp/(1+Gc*Gp);

y=step(Gcl,t);

ISE=0;

for j=1:1:N

44

ISE=ISE+(1-y(j))*(1-y(j))*del;

end

ise=ISE;

end

Kp=k(1);

Ki=k(2);

end

4.4 CONTROLLER DESIGNED USING SYNTHESIS METHOD

Designing a synthetic controller consist of designing a controller for a closed

feedback loop so as to get the desired closed loop transfer function. The formula used

is:

�5��� � ������

6 �57������57���

(3)

Considering a first order process whose transfer function is:

����� � ���8��

(4)

We can design controller such that the final closed loop transfer function is:

�57��� � ���857�

(5)

The transfer function of the desired controller is:

�5��� � ����/��� �

��8��89�

(6)

The discrete version of the above controller is:

��,� � ��, � �� � :";"<=">

/�,� � "<">/�, � �� (7)

where, T is the sampling time.

CODE:

i=1;

45

ebef=0;

mbef=0;

while i<=201

Y=obj.read();

y(i)=(5.0*Y)/(256.0);

e(i)=u(i)-y(i);

m(i)=mbef+(T+Tp)/Tr*e(i)-Tp/Tr*ebef;

mbef=m(i);

ebef=e(i);

M=floor(255.0*m(i)/5.0);

M=max(0,min(255,M));

obj.write(M);

i=i+1;

pause(del);

end

46

4.5 MODEL REFRENCE ADAPTIVE CONTROLLER

4.1 BLOCK DIAGRAM OF MRAC SYSTEM

CODE:

ardOBJ=arduino('COM23');

ardOBJ.pinMode(5,'output');

ardOBJ.analogWrite(5,0);

while ardOBJ.analogRead(0)>1

end

T=0.1;

t=0:T:20;

i=1;

while i<=201

Vin(i)=2;

47

i=i+1;

end

K=2;

Tm=4;

r=1.5;

i=1;

while i<=201

Vout(i)=ardOBJ.analogRead(0)*5.0/1024;

u(i)=K*Vin(i);

if (i==1)

Vm(i)=Vin(i)/(1+Tm/T);

end

if (i>1)

Vm(i)=(Tm/T*Vm(i-1)+Vin(i))/(1+Tm/T);

end

K=K-r*(Vout(i)-Vm(i))*Vin(i)*T;

op=max(min(floor(255.0/5.0*u(i)),255),0);

ardOBJ.analogWrite(5,op);

pause(T);

i=i+1;

end

delete(ardOBJ);

RESU

In this section we will present a

function is:

1

Gp(s)= ----------

(1+10*s)

5.1 OUTPUT FOR SYSTEM

SQUARE METHOD

Obtained Model:

0.968

---------------

8.955 s + 1

5.1 GRAPH FOR SYS

48

CHAPTER 5

RESULTS AND DISCUSSION

sent a case study of a RC Process whose theor

TEM IDENTIFICATION DONE BY LINE

R SYSTEM IDENTIFICATION ALGORIT

theoretical transfer

LINEAR LEAST

ORITHM

49

5.2 SERVO RESPONSE OF FIRST ORDER SYSTEM WITH PI

CONTROLLER

5.2 SERVO RESPONSE OF FIRST ORDER SYSTEM WITH PI

CONTROLLER

5.3 AUTOTUNED PI CONTROLLER

Autotuned Value:

Kp=19.0;

Ki=2.3;

50

5.4 SERVO RESPONSE OF FIRST ORDER SYSTEM WITH

MODEL REFERENCE ADAPTIVE CONTROLLER

5.4 SERVO RESPONSE OF FIRST ORDER SYSTEM WITH

MODEL REFERENCE ADAPTIVE CONTROLLER

51

5.5 SERVO RESPONSE OF FIRST ORDER SYSTEM WITH

CONTROLER DESIGNED USING SYNTHESIS METHOD

5.5 SERVO RESPONSE OF FIRST ORDER SYSTEM WITH

CONTROLER DESIGNED USING SYNTHESIS METHOD

From the graph, it is clearly visible that the dynamic response of the closed loop

process is much better than the dynamic response of the open loop process.

52

CHAPTER 6

CONCLUSION

We have acquired the data from a first order RC process through the data

acquisition card we designed and controlled it online through control algorithms

implemented in PC. The following modules were developed.

• Analog to digital convertor

• Digital to analog convertor

• Power delivering circuitry

• Interfacing algorithms

• Control algorithms coded in Matlab

• Online control of a process using the algorithms in PC

The following algorithms were implemented and the results were as desired.

• System identification using Linear Least Square Algorithm

• Proportional- Integral control

• Auto-tuning Proportional- Integral control

• Model Reference Adaptive Control

• Synthesis method of controller design

53

CHAPTER 7

REFERENCES

1) Jan Axelson, "Serial Port Complete", Lakeview Research, 2nd

Edition, 1998

2) Jan Axelson, "USB Complete-The Developer's Guide", Lakeview Research, 4th

Edition, 2009

3) Willis J. Tompkins, John G. Webster, "Interfacing sensors to the IBM PC", Prentice

Hal, 2nd

Edition, 1998

4) http://retired.beyondlogic.org/serial

5) http://www.engineersgarage.com/microcontroller/8051projects/interface-

ADC0804-serial-port-AT89C51-circuit

6) John Hyde, "USB Design by Example-A practical guide to building I/O Devices",

Intel University Press, 2nd

Edition, 2001

7) http://arduino.cc/playground/Interfacing/Matlab

8) David Trumper, "Analysis and Design of Digital Control Systems",

MITOpenCourseWare

9) Yoan D. Landau, Gianluca Zito, "Digital Control Systems: Design, Identification

And Implementation", Springer, 1st Edition, 2006