Line Follower Robot Using Micro-controllers

LINE FOLLOWER ROBOT USING Micro-Controllers

WALCHAND INSTITUTE OF TECHNOLOGY,SOLAPUR Robo Club BY WASI QAZI

Introduction

What is a uC ? In simple words -- a single chip Computer

Introduction Computer

uC

• uP

• uP

• RAM • HDD • Clock • Ports (Serial/USB) • Ports (Parallel) • Mic/Headphone Jack (ADC/ DAC) • Power Supply Unit • Reset • Mother-board

• Flash Memory • EEPROM • Clock Unit • SPI / UART Controllers • Digital I/O Ports • ADC • Power Supply Unit • Reset • IC

THE BLOCK DIAGRAM Clock 12Mhz

Main Power Supply

Motor Power Supply

Left Motor Microcontroller

Priority Encoder

HEX Inverter

H - Bridge DC Motor Control

Analog Comparators

NOR Gate

Sensor Array

Right Motor

Threshold Voltage

Sensors • A sensor is a device which measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. • They are used to provide feedback from the external environment

IR Sensor Pair IR sensor Pair

Transmitter (Tx)

Receiver (Rx)

Transmitter = LED( Light Emitting Diode) Receiver = Photodiode

Object / Line

Principle of Operation WHITE surface Maximum reflection T1 is turned ON Vout is LOW BLACK surface Minimum or No Reflection T1 is turned OFF Vout is HIGH

R1< R2

ADC BY OP-AMP:

G N D

+5v

Line Follower : Design The bot has two IR sensors facing downwards (towards the floor). Sleft

Sright

The separation between the sensors is such that in normal (correct) position of the bot , both the sensors are on white surface. ie separation > strip width The bot is driven by two wheel differential drive ie the two back wheels are driven by independent motors.

Line Follower : Algo

Sleft

When the bot is in correct pos, both sensors are on white & read LOW. The robot should move forward in this case. Sright

Sleft

Sright

Movement

LOW

LOW

Forward

Line Follower : Algo Sleft

When the bot is over line from right side, left sensor is on white & reads LOW whereas right sensor is on black & reads HIGH The robot should take a right turn in this case to come back in correct pos.

Sright

Sleft

Sright

Movement

LOW

HIGH

Right Turn

Line Follower : Algo S left

When the bot is over line from left side, right sensor is on white & reads LOW whereas left sensor is on black & reads HIGH The robot should take a left turn in this case to come back in correct pos.

S right

Sleft

Sright

Movement

HIGH

LOW

Left Turn

Line Follower

Sleft

Sright

Movement

Left Motor

Right Motor

LOW

LOW

Forward

Forward

Forward

LOW

HIGH

Right Turn

Forward

Back

HIGH

LOW

Left Turn

Back

Forward

Atmega16L : An Overview 8-bit Micro-cotroller 40-pin DIP 32 Programmable I/O Lines Operating Voltages

2.7 - 5.5V

Speed Grades 0 - 8 MHz 16K Bytes of In-System Self-programmable Flash program memory 512 Bytes EEPROM Two 8-bit Timer/Counters with Separate Prescalers and Compare Modes One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture Mode 8-channel, 10-bit ADC Programmable Serial USART Master/Slave SPI Serial Interface Programmable Watchdog Timer with Separate On-chip Oscillator On-chip Analog Comparator

Pin diagram

Block Daigram

Simplified Diagram

4 8bit Parallel Input-Output ports through which you can i/p or o/p digital data.

Power Supply

Port Architecture

uC

P O R T A

D D R A

P I N A

External world

Complete Program A program to o/p 33 (hex) on PortD and configure and read pins 2 and 7 of Port A #include void main( ) { unsigned int x,y; DDRD=0xFF; DDRA=0b01111011; PORTD=0x33; x=PINA.2; y=PINA.7; }

// all pins o/p // pin 7 & 2 i/p rest immaterial

L298N Motor Driver

Similarly other 2 o/p are connected /disconnected by I/p 3 & I/P 4 All the O/p’s operate independently, ie if all I/p 1-I/p 4 are 1, all O/p1 – O/p4 will be connected to +VPP L298 can provide 1A current / Output channel , therefore total of 4A. But heat sinks should be installed for such high currents . VPP can be anything in the range 2V- 46V , therefore any motor can be driven even though Atmega provides only 0/5 V.

A T M E G A

4 Outputs

4 Inputs

MOTOR DRIVER

MOTOR

Working of Motor Driver +VPP

O/p 1

I/p 1 ( O/p from uC)

O/p 2

I/p 2

O/p 3

I/p 3

O/p 4

If uC send ‘1’ to I/p 1, O/p is conn touC + VPP If send ‘0’ to I/p 1, O/p is conn to GND

I/p 4

GND

Working of Motor Driver +VPP

O/p 1

I/p 1 ( O/p from uC)

O/p 2

I/p 2

O/p 3

I/p 3

O/p 4

If uC send ‘1’ to I/p 2, O/p is conn touC + VPP If send ‘0’ to I/p 1, O/p is conn to GND

I/p 4

GND

Working of Motor

H-BRIDGE MOTOR CONTROL

H-BRIDGE MOTOR CONTROL

H-BRIDGE MOTOR CONTROL

H-BRIDGE USING TRANSISTOR

Motor Connection for Clockwise: +VPP

O/p 1

I/p 1 ( O/p from uC)

O/p 2

I/p 2

O/p 3

I/p 3

O/p 4

If uC send ‘1’ to I/p 2, O/p is conn touC + VPP If send ‘0’ to I/p 1, O/p is conn to GND

I/p 4

GND

Motor Connection for Anti-Clockwise: +VPP

O/p 1

I/p 1 ( O/p from uC)

O/p 2

I/p 2

O/p 3

I/p 3

O/p 4

If uC send ‘1’ to I/p 2, O/p is conn touC + VPP If send ‘0’ to I/p 1, O/p is conn to GND

I/p 4

GND

SPEED CONTROL BY PWM