line tracing robot

BLACK LINE TRACER AND OBSTACLE AVOIDANCE AUTONOMOUS ROBOT

BLACK LINE TRACER AND OBSTACLE AVOIDANCE

AUTONOMOUS ROBOT

Mini Project Report Submitted

By

DON MATHEW

In partial fulfilment of Sixth semester of

Bachelor of Technology

In

ELECTRONICS AND COMMUNICATION

OF

COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY

DEPARTMENT OF ELECTRONICS AND COMMUNICATION

COLLEGE OF ENGINEERING, POONJAR

KOTTAYAM-686 582

E-mail:-:[email protected]

Website:-http://www.cep.ac.in

Dept of Electronics and Communication College of Engineering Poonjar

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http://www.cep.ac.in/

mailto:[email protected]


ABSTRACT

Robotics is the science and technology of robots, their design, manufacture, and

application. Robotics requires a working knowledge of electronics, mechanics, and software.

Although the appearance and capabilities of robots vary vastly, all robots share the features of

a mechanical, movable structure under some form of autonomous control. This project

develops a line follower robot that detects a line drawn on a plain surface and moves through

it. The path can be visible like a black line on a white surface (or vice-versa) or it can be invisible

like a magnetic field. Sensing the line and constantly correcting wrong moves using feedback

mechanism forms an effective yet complex closed loop system. The robot also works on

another mode in which it detect and avoid the obstacles on the path. In this mode the

robot choose another path for its movement when an obstacle is detected. The user has the

option of setting the modes in which the robot should manure. The project implements line

tracking techniques and obstacle avoidance in microcontroller based embedded system. The

system also controls the motors that moves the robot through its path.


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CONTENTS

1. INTRODUCTION 01

2. REQUIREMENTS FOR THE PROJECT 02

3.1 HARDWARE REQUIREMENTS 02

3.2 SOFTWARE REQUIREMENTS 02

3. BLOCK DIAGRAM 03

4. BLOCK LEVEL DESCRIPTION 04

5. CIRCUIT DIAGRAM 05

6. DESIGN 06

7. CIRCUIT PARTS 07

7.1 REGULATED POWER SUPPLY 09

7.2 MOTION CONTROL 09

7.3 H-BRIDGE MOTOR CONTROL 10

7.4 IR SENSOR 18

7.5 COMPARATOR 18

7.6 D.C. MOTORS 19

8. WORKING 20

9. PCB LAYOUT 21

10. FLOW CHART 23

11. PROGRAM CODE24

12. APPLICATIONS 32

13. FUTURE SCOPES 32


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14.LIMITATIONS 32

15. RESULTS AND CONCLUSIONS 33

16. BIBLIOGRAPHY 34


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1. LIST OF FIGURES

Figure 1 Block Diagram 07

Figure 2 Circuit Diagram 10

Figure 3 Block Diagram of Regulated Power Supply 13

Figure 4 Regulated Power Supply Circuit Diagram 14

Figure 5 L293D Block Diagram 15

Figure 6PIC 16F877A 17

Figure 7 IR sensor25

Figure 8 PCB Layout 30

Figure 9PCB Layout 31

Figure 10Flow chart 33


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1. INTRODUCTION

The word "robot" originates from the Czech word for forced labour or serf. Robots are

electronic devices intended to perform a desired function. Many refer to them as "machines",

however, a drill press is a machine, yet it requires an operator to perform its function, where

robots can be programmed to do it themselves. Robots have the potential to change our

economy, our health, our standard of living, our knowledge and the world in which we live.

Robotics is not only a science, but it is also an art. There are many different versions of robots

that can be made.

The Line follower robot is a mobile machine that can detect and follow the line drawn on the

floor. Generally, the path is predefined like a black line on a white surface Therefore, this kind

of Robot should sense the line with its Infrared Ray (IR) sensors that installed under the robot.

After that, the data is transmitted to the processor by specific transition buses. Hence, the

processor is going to decide the proper commands and then it sends them to the driver and

thus the path will be followed by the line follower robot. If there is any obstacle on the path of

the robot, it takes a deviation.


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2. REQUIREMENTS FOR THE PROJECT

Both hardware and software are required for the successful completion of the project

2.1 HARDWARE REQUIREMENTS

Hardware requirements include

PIC 16F877A: It is a 40 pin microcontroller chip Bridge Rectifier: Used in power supply LM 7805: Voltage regulator Crystal oscillator: 4 MHZ for clock signal generation Tact switch: Used for resetting PIC and mode selection Resistors: Various ranges of carbon resisters are required

10K, 1K, 4.7K, 100Ω, 220Ω, 470 Ω Capacitors: Various electrolytic & paper capacitors are used

0.1µF, 100µF, 1000µF, 22pF Transistors: BC547 Sensors: TSOP 1738, IR LED, Photodiode Motor control: L293D is used Comparator: LM358N for deriving digital outputs Motor: BO Motor 45 rpm Tyre Castor wheel: for sliding over the surface

2.2 SOFTWARE REQUIREMENT

Software requirements include

MicroC Simulation software PICkit 2 v2.61

3.BLOCK DIAGRAM


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IR LIGHT

SURFACE

LEFT LINE MIDDLE LINE RIGHT

SENSOR SENSOR SENSOR SENSOR SENSOR

PIC 16F877A

MOTOR

DRIVER

MOTOR MOTORFigure 1


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4.BLOCK LEVEL DESCRIPTION

The PIC microcontroller requires a +5V voltage supply and for other section of the circuit too. So a related dc voltage of 5V can be delivered from the 230V supply. The 230V supply is step downed to an appropriate value and after that it is rectified and regulated by IC 7805 voltage regulator. In order to facilitate high emission we employ IR LEDs. The rays emitted by these LEDs incident on the surface on which the line is drawn. The various operation of the system is controlled by software that is embedded in the PIC. We use PIC16F877A microcontroller due to its high number of I/O pins. It also employs more number of registers. The two line sensors track the path and the left, middle and right obstacle sensor senses the obstacle. The output from the line sensor and obstacle sensor is given to the PIC. Motor moves according to the instructions from the PIC.

5. CIRCUIT DIAGRAM


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Figure 2

6. DESIGN


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PIC 16F877A, the central controller operates at 5v. The control IC for motor , L293D has an operating voltage of 9V.So these voltage levels are produce from a 230V ac supply by a 230V:9V transformer followed by two 9V and 5V dc regulators. The operating voltageof all other sections are hence divided at 5V. The value for resistance affects the source IR brightness ,for maximum brightness we set resistance to give the maximum allowable forward current for the IR led. For the proper operation point of IR LED current required is .051 A critically. So we connect a resistor R1 in series with LED for proper current control. The IR detector operates with proper light sensing at an operating current value equal to 0.05 A. So resistance to be connected in series with IR detector is R=V/I=5/0.05=100Ω .When operated at a current of 0.5mA BC547 operates at the quiescent value. So resistance series with BC547 is 5V/0.5mA =10R. PIC 16F877A operates at a clock frequency of 20 MHz (use 4MHz).

6.1 VOLTAGE REGULATOR

o To maintain a constant dc output voltage.

o It also rejects any ac ripple voltage that is not removed by the filter.

o It includes protective features such as short circuit protection, current limiting, thermal shutdown, or over-voltage protection.

The 230v ac mains input is stepped down to 12v and fed to Bridge rectifier input. The rectified output is pulsating and is fed to the capacitive filter for smoothening. To obtain regulated output a voltage regulator IC (LM7805) is used. Hence 5v dc regulated output is obtained. But here in robot for mobile applications we use a battery source of 9v or 12v which is directly given to LM7805 voltage regulator and the required 5v is obtained. Otherwise for testing and development process of the robot we can use the circuit with direct ac input into the transformer.

6.2 MOTION CONTROL


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This is done with help of output commands from PIC microcontroller. IC L293D is used to drive the 45rpm motor as the PIC can’t directly drive 12v motors. L293D - The Device is a monolithic integrated high voltage, high current four channel driver designed to accept standard DTL or TTL logic levels and drive inductive loads and switching power transistors. To simplify use as two bridges each pair of channels is equipped with an enable input. This device is suitable for use in switching applications at frequencies up to 5 kHz

7.CIRCUIT PARTS

7.1 REGULATED POWER SUPPLY:

Transformer Rectifier Filter Voltage regulator

Block diagram of regulated power supply

Figure 3 Transformer

o Used for voltage transformation.o Step-down transformer used for down-conversion of ac line voltage to a smaller

peak voltage.o Step down in voltage achieved by decreasing the voltage and proportionally

increasing the current.

Rectifiero Converts the sinusoidal ac voltage into either positive or negative pulsating dc.


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o P-N junction diode, which conducts when forward biased and practically does not conduct when reverse biased, can be used for rectification.

o Rectifiers may be either half-wave rectifiers or full-wave rectifiers (centre-tap or bridge) type.

o Bridge rectifier is used because output for the entire cycle of input voltage is obtained.

Filtero To reduce ac components from the rectifier output voltage.o Capacitive filters are used with less charging time and more discharging time.o The RC charge time of the filter capacitor must be short and the RC discharge

time must be long to eliminate ripple action when using this filter. In other words, the capacitor must charge up fast with preferably no discharge at all.

The entire process of rectification and filtering is obtained using a 1A Bridge IC.

Voltage regulatoro To maintain a constant dc output voltage. o It also rejects any ac ripple voltage that is not removed by the filter. o It include protective features such as short-circuit protection, current limiting,

thermal shutdown, orover-voltage protection.

Regulated power supply circuit diagram

Figure 4

The 230v ac mains input is stepped down to 12v and fed to Bridge rectifier input. The rectified optput is pulsating and is fed to the capacitive filter for smoothening. To obtain regulated


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http://www.circuitstoday.com/full-wave-bridge-rectifier

http://www.circuitstoday.com/centre-tap-full-wave-rectifier

http://www.circuitstoday.com/centre-tap-full-wave-rectifier

http://www.circuitstoday.com/half-wave-rectifiers


output a voltage regulator IC (LM7805) is used. Hence 5v dc regulated output is obtained. But here in robot for mobile applications we use a battery source of 9v or 12v which is directly given to LM7805 voltage regulator and the required 5v is obtained. Otherwise for testig and development process of the robot we can use the circuit with direct ac input into the transformer.

7.2 MOTION CONTROL:

This is done with help of output commands from PIC microcontroller. Here an ic L293D is used to drive the 45rpm geared motor as the PIC can’t directly drive 12v motors.

L293D - The Device is a monolithic integrated high voltage,high current four channel driver designed to accept standard DTL or TTL logic levels and drive inductive loads and switching power transistors.To simplify use as two bridges each pair of channels is equipped with an enable input. A separate supply input is provided for the logic, allowing operation at a lower voltage and internal clamp diodes are included. This device is suitable for use in switching applications at frequencies up to 5 kHz.

Figure 5

7.3 H-BRIDGE MOTOR CONTROL

DC motors are generally bi-directional motors. That is, their direction of rotation


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can be changed by just reversing the polarity. But once the motors are fixed, control

becomes tricky. This is done using the H-Bridge.

IN1 IN2 IN3 IN4 OPERATION1 0 1 0 BOTH MOTORS FORWARD (MOVES FORWARD)1 0 0 1 RIGHT MOTOR BACKWARD, LEFT MOTOR FORWARD (TURN RIGHT)0 1 1 0 RIGHT MOTOR FORWARD, LEFT MOTOR BACKWARD (TURN LEFT)


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7.4 PIC 16F877A

Figure 6

a)Microcontroller Core Features:

• Only 35 single word instructions to learn


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• All single cycle instructions except for program branches which are two cycle

• Operating speed: DC - 20 MHz clock input

• 8K × 14 word Flash program memory, 368×8 bytes RAM,

256×8 bytes of EEPROM Data Memory

• Direct, indirect and relative addressing modes

• Power-on Reset (POR)

• Power-up Timer (PWRT) and Oscillator Start-up Timer (OST)

• Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation

• Programmable code protection

• Power saving SLEEP mode

• Selectable oscillator options

• Low power, high speed CMOS FLASH/EEPROM technology

• Fully static design

• In-Circuit Serial Programming (ICSP) via two pins

• Single 5V In-Circuit Serial Programming capability

• Processor read/write access to program memory

b)Peripheral Features:

• Port A: 6bit bidirectional port

• Port B , C,D: 8bit and Port E:3 bit bidirectional port

• Timer0: 8-bit timer/counter with 8-bit pre-scalar

• Timer1: 16-bit timer/counter with pre-scalar, can be incremented during

SLEEP via external crystal/clock

• Timer2: 8-bit timer/counter with 8-bit period register, pre-scalar and postscalar

• Two Capture, Compare, PWM modules (CCP modules)

• 10-bit, 5 - channel Analog-to-Digital converter

• Synchronous Serial Port (SSP) with SPI (Master mode) and I2C

(Master/Slave)

Universal Synchronous Asynchronous Receiver


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• Transmitter (USART/SCI) with 9-bit address detection

• Brown-out detection circuitry for Brown-out Reset (BOR)

c )MEMORY ORGANIZATION

There are three memory blocks in each of these PIC micro MCUs. The Program Memory and

Data Memory have separate buses so that concurrent access can occur. The third block is

EEPROM.

i )Program Memory Organization

The PIC16F87X devices have a 13-bit program counter capable of addressing an 8K x 14

program memory space. The PIC16F877/876 devices have 8K x 14words of FLASH program

memory. Accessing a location above the physically implemented address will cause a wrap

around. The reset vector is at 0000h and the interrupt vector is at 0004h.

ii )Data Memory Organization

The data memory is partitioned into multiple banks which contain the General Purpose

Registers and the Special Function Registers. Bits RP1 (STATUS<6>) andRP0 (STATUS<5>) are the

bank select bits. Each bank extends up to 7Fh (128 bytes). The lower locations of each bank are

reserved for the Special Function Registers. Above the Special Function Registers are General

Purpose Registers, implemented as Static RAM. All implemented banks contain Special Function

Registers. Some “high use” Special Function Registers from one bank may be mirrored in another

bank for code reduction and quicker access.

d )DATA EEPROM AND FLASH PROGRAM MEMORY


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The Data EEPROM and FLASH Program Memory are readable and writable during

normal operation over the entire VDD range. A bulk erase operation may not be issued from

user code (which includes removing code protection). The data memory is not directly mapped

in the register file space. Instead it is indirectly addressed through the Special Function

Registers (SFR). There are six SFRs used to read and write the program and data EEPROM

memory. EECON1, EECON2, EEDATA, EEDATH, EEADR EEADRH. The EEPROM data memory

allows byte read and writes. When interfacing to the data memory block, EEDATA holds the 8-

bit data for read/write and EEADR holds the address of the EEPROM location being accessed.

The registers EEDATH and EEADRH are not used for data EEPROM access. These devices have

up to 256 bytes of data EEPROM with an address range from 0h to FFh. The program memory

allows word reads and writes. Program memory access allows for checksum calculation and

calibration table storage. A byte or word write automatically erases the location and writes the

new data (erase before write). Writing to program memory will cease operation until the write

is complete.

i )Reading the Data EEPROM Memory

To read a data memory location, the user must write the address to the EEADR register,

clear the EEPGD control bit (EECON1<7>) and then set control bit RD (EECON1<0>). The data is

available in the very next instruction cycle of the EEDATA register; therefore it can be read by

the next instruction. EEDATA will hold this value until another read operation or until it is

written to by the user (during a write operation).

ii)Writing to the Data EEPROM Memory

To write an EEPROM data location, the address must first be written to the EEADR

register and the data written to the EEDATA register. The write will not initiate if the above

sequence is not exactly followed. It is strongly recommended that interrupts be disabled during

this code segment. Additionally, the WREN bit in EECON1 must be set to enable writes. This

mechanism prevents accidental writes to data EEPROM due to unexpected code execution (i.e.,


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runaway programs). The WREN bit should be kept clear at all times, except when updating the

EEPROM. The WREN bit is not cleared by hardware.

e)I/O PORTS

Some pins for these I/O ports are multiplexed with an alternate function for the

peripheral features on the device. In general, when a peripheral is enabled, that pin may not be

used as a general purpose I/O pin.

f)PORTA and the TRISA Register

PORTA is a 6-bit wide bi-directional port. The corresponding data direction register is

TRISA. Setting a TRISA bit (=1) will make the corresponding PORTA pin an input (i.e., put the

corresponding output driver in a hi-impedance mode). Clearing a TRISA bit (=0) will make the

corresponding PORTA pin an output (i.e., put the contents of the output latch on the selected

pin).Reading the PORTA register reads the status of the pins, whereas writing to it will write to

the port latch. All write operations are read-modify-write operations. Therefore, a write to a port

implies that the port pins are read; the value is modified and then written to the port data latch.

Pin RA4 is multiplexed with the Timer0 module clock input to become the RA4/T0CKI pin. The

RA4/T0CKI pin is a Schmitt Trigger input and an open drain output. All other PORTA pins have TTL

input levels and full CMOS output drivers. Other PORTA pins are multiplexed with analog inputs

and analog VREF input. The operation of each pin is selected by clearing/setting the control bits

in the ADCON1 register (A/D Control Register1). The TRISA register controls the direction of the

RA pins, even when they are being used as analog inputs. The user must ensure the bits in the

TRISA register are maintained set when using them as analog inputs.

g)PORTB and the TRISB Register


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PORTB is an 8-bit wide, bi-directional port. The corresponding data direction register is

TRISB. Setting a TRISB bit (=1) will make the corresponding PORTB pin an input (i.e., put the

corresponding output driver in a hi-impedance mode). Clearing a TRISB bit (=0) will make the

corresponding PORTB pin an output (i.e., put the contents of the output latch on the selected

pin). Three pins of PORTB are multiplexed with the Low Voltage Programming function;

RB3/PGM, RB6/PGC and RB7/PGD. The alternate functions of these pins are described in the

Special Features Section. Each of the PORTB pins has a weak internal pull-up. A single control bit

can turn on all the pull-ups. This is performed by clearing bit RBPU (OPTION_REG<7>). The weak

pull-up is automatically turned off when the port pin is configured as an output. The pull-ups are

disabled on a Power-on Reset of PORTB’s pins, RB7:RB4, have an interrupt on change feature.

Only pins configured as inputs can cause this interrupt to occur (i.e. any RB7:RB4 pin configured

as an output is excluded from the interrupt on change comparison).The input pins (of RB7:RB4)

are compared with the old valuelatched .

h)PORTC and the TRISC Register

PORTC is an 8-bit wide, bi-directional port. The corresponding data direction register is

TRISC. Setting a TRISC bit (=1) will make the corresponding PORTC pin an input (i.e., put the

corresponding output driver in a hi-impedance mode). Clearing a TRISC bit (=0) will make the

corresponding PORTC pin an output (i.e., put the contents of the output latch on the selected

pin). PORTC is multiplexed with several peripheral functions (Table 3-5). PORTC pins have Schmitt

Trigger input buffers. When the I2C module is enabled, the PORTC (3:4) pins can be configured

with normal I2C levels or with SMBUS levels by using the CKE bit (SSPSTAT <6>).When enabling

peripheral functions, care should be taken in defining TRIS bits for each PORTC pin. Some

peripherals override the TRIS bit to make a pin an output, while other peripherals override the

TRIS bit to make a pin an input. Since the TRIS bit override is in effect while the peripheral is

enabled, read-modify write instructions (BSF, BCF, XORWF) with TRISC as destination should be

avoided.

i)PORTD and TRISD Registers


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PORTD is an 8-bit port with Schmitt Trigger input buffers. Each pin is individually configurable as

an input or output.

j)PORTE and TRISE Registers

This section is not applicable to the PIC16F873 or PIC16F876. PORTE has three pins,

RE0/RD/AN5, RE1/WR/AN6 and RE2/CS/AN7, which are individually configurable as inputs or

outputs. These pins have Schmitt Trigger input buffers. I/O PORTE becomes control inputs for the

microprocessor port when bit PSPMODE (TRISE<4>) is set. In this mode, the user must make sure

that the TRISE<2:0> bits are set (pins are configured as digital inputs). Ensure ADCON1 is

configured for digital I/O. In this mode, the input buffers are TTL. Register 3-1 shows the TRISE

register, which also controls the parallel slave port operation. PORTE pins are multiplexed with

analog inputs. When selected as an analog input, these pins will read as ’0’s. TRISE controls the

direction of the RE pins, even when they are being used as analog inputs. The user must make

sure to keep the pins configured as inputs when using them as analog inputs

k)TIMER0 MODULE

The Timer0 module timer/counter has the following features: 8-bit timer/counter, Readable and

writable, 8-bit software programmable prescaler, Internal or external clock select, Interrupt on

overflow from FFh to 00h, Edge select for external clock. Timer mode is selected by clearing bit

T0CS (OPTION_REG<5>).Counter mode is selected by setting bit T0CS (OPTION_REG<5>). In

counter mode, Timer0 will increment either on every rising or falling edge of pin RA4/T0CKI. The

incrementing edge is determined by the Timer0 Source Edge Select bit T0SE (OPTION_REG<4>).

Clearing bit T0SE selects the rising edge. The TMR0 interrupt is generated when the TMR0

register overflows from FFh to 00h. This overflow sets bit T0IF (INTCON<2>). The interrupt can be

masked by clearing bit T0IE (INTCON<5>). Bit T0IF must be cleared in software by the Timer0

module interrupt service routine before re-enabling this interrupt.

i)Using Timer0 with an External Clock


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When no prescaler is used, the external clock input is the same as the prescaler output.

The synchronization of T0CKI with the internal phase clocks is accomplished by sampling the

prescaler output on the Q2 and Q4 cycles of the internal phase clocks. Therefore, it is necessary

for T0CKI to be high for at least 2Tosc (and a small RC delay of 20 ns) and low for at least 2Tosc

(and a small RC delay of 20 ns).

l)TIMER1 MODULE

The Timer1 module is a 16-bit timer/counter consisting of two 8-bit registers (TMR1H and

TMR1L), which are readable and writable. The TMR1 Register pair (TMR1H:TMR1L) increments

from 0000h to FFFFh and rolls over to 0000h. The TMR1 Interrupt, if enabled, is generated on

overflow, which is latched in interrupt flag bit TMR1IF (PIR1<0>). This interrupt can be

enabled/disabled by setting/clearing TMR1 interrupt enable bit TMR1IE (PIE1<0>).Timer1 can

operate in one of two modes: As a timer and as a counter.

7.5 IR SENSOR


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It consists of an infrared emitting diode (λ = 950nm) and a photodiode mounted to face

each other on a converging optical axis in a black plastic housing. The phototransistor responds

to radiation from the emitting diode only when no object is present within its field of view. This

sensor is physically modified so that the emitter and detector face the same direction and thus

the modified sensor serves the purpose of an optical-reflective sensor. The sensor has a focal

length of 8mm, thus the surface must be at an optimum distance of 1.6cm. The original and

modified sensors are shown below.

Figure 77.6 COMPARATOR

A comparator is a circuit which compares a signal voltage applied at one input of

an op-amp with a known reference voltage at the other input, and produces either a high

or a low output voltage, depending on which input is higher. The reference voltage is generated

by the 50k POT and given to all the comparators to the non-inverting input. When the

respective sensor is on the line, the emitted light is absorbed by the line and the transistor is

the cut-off mode, thus a potential of 4.6V is given to the inverting input which is greater than

Vref (which is chosen to be 2.5V), thus the output of the comparator goes low. When the

sensor is not on the line (reflective white surface) the potential across the detector is usually

0.6V. Thus the output of the comparator goes high (the non-inverting input has a greater


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potential). Thus the output of the comparator goes low only when the sensor is over the line.

The comparator is open collector, and hence a pull-up resistor of 10 kΩis required at the

output.

7.7 D.C. MOTORS

DC motors are widely used, inexpensive, small and powerful for their size.Reduction

gearboxes are often required to reduce the speed and increase the torque output of the motor.

Unfortunately more sophisticated control algorithms are required to achieve accurate control

over the axial rotation of these motors. Although recent developments in stepper motor

technologies have come a long way, the benefits offered by smooth control and high levels of

acceleration with DC motors far outweigh any disadvantages. several characteristics are

important when selecting DC motors and these can be split into two specific categories. The

first category is associated with the input ratings of the motor and specifies its electrical

requirements, like operating voltage and current. The second category is related to the motor's

output characteristics and specifies the physical limitations of the motor in terms of speed,

torque and power.

7.8 CRYSTAL OSCILLATOR

The clock frequency is provided by one 4Mhz crystal which is connected acrossthe OSC1 & OSC2 pins. This provides an instruction execution time of 200ns.

8. WORKING


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Common features required for line followers:

Follow a black line Stop if the line disappears Avoid an obstacle if present

The line following robot will need to see the line, therefore we require a light detector of some sort. Also the line follower robot needs to do this regardless of the ambient conditions. So the robot will also need its own illumination source.

The basic steps to be performed include:

facilitation of emission of light rays detection of reflected rays processing the received signal enable proper motor operation

LINE FOLLOWING MODE

The line is tracked by the IR sensor. It consists of an infrared emitting diode and a photodiode. In order to facilitate light emission we employ IR LEDs. The rays emitted by these LEDs incident on the surface on which the line is drawn. The white surfaces on which the lines are drawn, reflects these emitted rays. These emitted rays are detected by photodiodes. On the other hand the black coloured surface absorbs the rays. The photodiode responds to radiation from the emitting diode and its output is fed to the comparator. Comparator compares the input with a reference voltage level and converts it to a digital value. These different outputs are fed to the input of the ADC of PIC16F877A. The PIC is so programmed to trace the black coloured surface or black line. The motor driving IC L293D facilitates different motor operations and helps the circuit trace the path correctly.

OBSTACLE DETECTION MODE

Obstacle detection is made possible by using three sensors for detecting obstacles present at the front end, right and left ends. If the rays emitted by the LEDs get sensed by the sensor TSOP 1738 with no delay, then it indicates the presence of no obstacle. In case of the presence of any obstacle the line follower stops further proceeding. The circuit then checks for any available path without obstacle for further traversal and continue its motion in that path if any. The motor driving IC L293D facilitates different motor operation.


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9.PCB LAYOUT

Figure 8


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Figure 9

The pcb layout was designed and simulated with help of software named orcad.

STEPS IN PCB MAKING The pcb layout made with proteus was printed on a paper The pcb layout was printed on a copper clad by pressing the printed layout with a hot

iron box The layout obtained on the copper clad is verified and connections are darkened Holes for placing components were drilled The printed copper clad was dipped in ferrous sulphate solution and was placed in sun

light The etching was completed in 10 mins and the printed circuit boad was ready The components were soldered into the pcb


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10. FLOW CHART

Figure 10


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11. PROGRAM

// Directives

#define SW PORTB.F7

#define OBLED PORTD.F4

#define LFLED PORTD.F5

#define LIN1 PORTD.F2

#define LIN2 PORTD.F3

#define RIN1 PORTC.F4

#define RIN2 PORTC.F5

#define TSOPR PORTA.F0

#define TSOPM PORTA.F1

#define TSOPL PORTA.F2

#define PHSL PORTD.F0

#define PHSR PORTD.F1

// End Directives

// Variables

char mode = 0,ir_stat = 1,turn_cnt=0,turn_mode=0;

// End Variables

// Initialize MCU

voidinit_mcu ( )


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ADCON1 = 0x06;

TRISA = 0xFF; // set port A as input port

TRISB = 0xFF; // set port B as input port

TRISC = 0x00; // set port C as output port

TRISD = 0x03; /* set last 2 ports of D as input and other ports as output ports*/

PORTC = 0x00; // out 00 to port C

PORTD = 0x00; // out 00 to port D

Delay_ms (1000);

OBLED = 1;

LFLED = 1;

While (SW==1)

;

OBLED = 0;

LFLED = 0;

Delay_ms (2000);

// End Initialize MCU

// ROUTINES FOR LINE DETECTION

// Vehicle Move Straight

Void move_strt ( )

LIN1 = 1; // left motor rotates forward

LIN2 = 0;


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RIN1 = 1; // right motor rotates forward

RIN2 = 0;

// End Vehicle Moves Straight

// Vehicle Moves Reverse

Void move_rvrs ( )

LIN1 = 0;

LIN2 = 1; //left motor rotates backward

RIN1 = 0;

RIN2 = 1; // right motor rotates backward

// End Vehicle Moves Reverse

// Vehicle Moves Right

Void move_rght ( )

LIN1 = 1; // left motor rotates forward

LIN2 = 0;

RIN1 = 0;

RIN2 = 1; //right motor rotates backward

Delay_ms (20);

// End Vehicle Moves Right


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// Vehicle Moves Left

void move left()

LIN1 = 0;

LIN2 = 1; //left motor rotates backward

RIN1 = 1; //right motor rotates forward

RIN2 = 0;

Delay_ms (20);

// End Vehicle Moves Left

// Vehicle Stops

Void vhcl_stop ( )

LIN1 = 0; // left motor stops

LIN2 = 0;

RIN1 = 0; // right motor stops

RIN2 = 0;

// End Vehicle Stop

// Main Routine

// ROUTINE FOR OBSTACLE DETECTION

Void main ()


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init_mcu ( ); //initialise the controller unit

While (1)

if (SW==0)

Delay_ms(300);

If (mode==0)

mode = 1;

else if(mode==1)

mode = 0;

If (mode==1) //mode for obstacle detection

If (ir_stat==1)

PWM1_Init(38000); //PWM inputs to TSOP

PWM1_Start();

PWM1_Set_Duty(20);

ir_stat = 0;

OBLED = 0;

LFLED = 1;

if(TSOPM==1 && TSOPR==1 && TSOPL==1) //no obstacle

move_strt(); //moves straight


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else if((TSOPM==1&&TSOPR==1&&TSOPL==0)||(TSOPM==0&&TSOPR==1&&TSOPL==0)) //obstacle at left or at left & middle

move_rght(); //moves right

else if((TSOPM==1&&TSOPR==0&&TSOPL==1)||(TSOPM==0&&TSOPR==0&&TSOPL==1)) //obstacle at right or at right & middle

move_left(); // moves left

else if(TSOPM==0 && TSOPR==1 && TSOPL==1) // obstacle at mibble

vhcl_stop(); //stops

move_rvrs(); // moves reverse

Delay_ms(500);

vhcl_stop(); //stops

if(turn_cnt>=5)

turn_cnt = 0;

if(TSOPR==1 &&turn_mode==0) // no obstacles at right

//checks if movement to right is possible

if(turn_cnt<=2)

move_rght(); //moves right

Delay_ms(150);


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turn_cnt++;

else

turn_mode = 1; //mode for left

else if(TSOPL==1 &&turn_mode==1) //no obstacles at left

//checks if movement to left is possible

if(turn_cnt>=2 &&turn_cnt<=5)

move_left(); //moves left

Delay_ms(150);

turn_cnt++;

else

turn_mode = 0; //mode for right

turn_cnt = 0;

else if(mode==0) //line detection mode

PWM1_Stop(); // cuts off TSOP

ir_stat = 1;


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OBLED = 1;

LFLED = 0;

if(PHSL==1 && PHSR==1) // both sensors on the line

move_strt(); // moves straight

else if(PHSL==0 && PHSR==1) // left sensor off the line

move_rght(); // moves right

else if(PHSL==1 && PHSR==0) //right sensor off the line

move_left(); //moves left

else // both sensors off the line

vhcl_stop(); // stops

// End Main Routine


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12. APPLICATIONS

Industrial automated equipment carriers. Automated traffic. Tour guides in museums and other similar applications. Second wave robot reconnaissance operations. In large office buildings for message transfer. Medicine transportation in hospitals.

13. FUTURE SCOPE

Software control of the line type (dark or light) to make automatic detection possible. Obstacle detecting sensors to avoid physical obstacles and continue on the line. Distance sensing and position logging & transmission.

14. LIMITATIONS

Calibration is difficult and it is not easy to set a perfect value The steering mechanism is not easily implemented in huge vehicles and impossible for

non electric vehicles. Few curves are not made efficiently and must be avoided Lack of four wheel drive makes it not suitable for a rough terrain Use of IR even though solves a lot of problems pertaining to interference, makes it hard

to debug a faulty error. Lack of speed control makes the robot unstable at times.


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15. RESULTS AND DISCUSSIONS

The project “BLACK LINE TRACER AND OBSTACLE AVOIDANCEAUTONOMOUS ROBOT”

is completed successfully. The robot is made with proper functioning of line tracking and

obstacle detection. We are thankful to all those who gave us valuable help and guidance to

complete our project work successfully.

16.BIBLIOGRAPHY

1) DESIGN WITH PIC MICROCONTROLLERS : JOHN.B.PEATMAN

WEBSITES

1) http://www.microchip.com

2) http://www.electronicsforu.com

3) http://ieeexplore.ieee.org

4) http://www.extremeelectronics.co.in

Thank You...!


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http://www.extremeelectronics.co.in/

http://ieeexplore.ieee.org/

http://www.electronicsforu.com/

http://www.microchip.com/

line tracing robot

Documents

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kind of robot

dept of electronics

introductionthe word

line tracking techniques

block diagram circuit

ir sensor25 figure

technology of robots