Making a Line Follower Robot Without Microcontroller


  1. 1. Step by Step: Line Follower Robot Without Microcontroller

Line follower is an autonomous robot which follows either black line in white area or white line in black area. Robot must be able to detect particular line and keep following it.

For special situations such as cross over’s where robot can have more than one path which can be followed, predefined path must be followed by the robot.

Line following is a task in which robot has to follow the line. It must be capable of taking various degrees of turns to follow the curved lines also.

Line Follower RobotLine Follower Robot without Microcontroller

Image: Line Follower Robot without Microcontroller

The Line following Robot moves to follow a line drawn on the floor. This Robot follows the black line which is drawn over the white surface .The line sensors are used to sense the line. When the signal falls on the white surface, it gets reflected and if it falls on the black surface, it is not reflected this principle is used to scan the Lines for the Robot.

The Robot should be capable of taking various degrees of turns and must be insensitive to environmental factors such as lighting and noise.

2. Principal of Operation

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Explanation of block diagram

 

Stage 1  

Line sensor plate

Reflection of light

This stage consists of reflection of light phenomena in which light reflect from the plane surface.

LED:

LEDs are used as indicator lamps in many devices and are increasingly used for general lighting.

Long leg is positive.

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Short leg is negative.

LDR:

A photoresistor light dependent resistor (LDR) or is a resistor whose resistance decreases as with increasing incident light intensity.

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Reflection of light on any plane surface 

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Reflection of light on white surface is More.

Reflection of light on black surface is Less.

Line sensor

Line sensor is a combination of LDR (Light Dependent Resistor) and LED (Light Emitting Diode) which works on phenomenon of Reflection and Absorption.

White color surface reflects the most of the color falling on them while Black color surface absorbs all the light  falling on them.

So, a major part of light emitted by LED is reflected by white surface and so, LDR detects it.

Image of line sensor

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Stage 2

Logic circuit Section

Logic circuit consists of LM324 ic which is used for to generate logic signal. It take input from the line sensor and generate the output signal which is used for to drive the motors.

LM324 IC

LM324 is a 14pin IC consisting of four independent operational amplifiers (op-amps) compensated in a single package. Op-amps are high gain electronic voltage amplifier with differential input and, usually, a single-ended output. The output voltage is many times higher than the voltage difference between input terminals of an op-amp.

Pin Diagram

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Pin Description: 

 Pin No

 Function

 Name

1

Output of 1st comparator

Output 1

2

Inverting input of 1st comparator

Input 1-

3

Non-inverting input of 1st comparator

Input 1+

4

Supply voltage; 5V (up to 32V)

Vcc

5

Non-inverting input of 2nd comparator

Input 2+

6

Inverting input of 2nd comparator

Input 2-

7

Output of 2nd comparator

Output 2

8

Output of 3rd comparator

Output 3

9

Inverting input of 3rd comparator

Input 3-

10

Non-inverting input of 3rd comparator

Input 3+

11

Ground (0V)

Ground

12

Non-inverting input of 4th comparator

Input 4+

13

Inverting input of 4th comparator

Input 4-

14

Output of 4th comparator

Output 4

Stage 3

Logic inverter circuit section

In this logic inverter circuit section 74HC04D IC is used for to invert the logic. The logic is  given to it ’s input terminal in the form of logic 0 and logic 1.

74HC04 IC

This IC is used for to invert the logic. The input are given from the output of LM324 IC and this IC output are used for to drive the motor. It also provide buffering that is amplification for the motor driver IC.

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Stage 4

Motor Driving Stage

In this stage the motor driver l293D IC is used for to drive the motor. As the signal comes from the inverter IC it drives the motor according to signals comes.

L293D IC

L293D is a dual H-bridge motor driver integrated circuit (IC). Motor drivers act as current amplifiers since they take a low-current control signal and provide a higher-current signal. This higher current signal is used to drive the motors.

L293D contains two inbuilt H-bridge driver circuits. In its common mode of operation, two DC motors can be driven simultaneously, both in forward and reverse direction. The motor operations of two motors can be controlled by input logic at pins 2 & 7 and 10 & 15. Input logic 00 or 11 will stop the corresponding motor. Logic 01 and 10 will rotate it in clockwise and anticlockwise directions, respectively.

Enable pins 1 and 9 (corresponding to the two motors) must be high for motors to start operating. When an enable input is high, the associated driver gets enabled. As a result, the outputs become active and work in phase with their inputs. Similarly, when the enable input is low, that driver is disabled, and their outputs are off and in the high-impedance state.

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Truth table for robot Movement

Sr.No

IN1

IN2

IN3

IN4

Movement of robot

1

1

0

0

1

Forward

2

0

1

1

0

Backward

3

0

1

0

1

Left

4

1

0

1

0

Right

Note

You can exchange the motor wire with output pins to make the above respective movement.

Accessories Required to make line follower robot

Sr.No.

Component Name

Quantity

1. Double AA batteries cell holder 1
2. Chassis  ( Robotic  Platform) 1
3 Breadboard 1
4 Nipper 1
5. Stripper 1
6. One  core wire 1
7. Nose pliers 1
8 Screw driver 1

3. Mechanical assembly of robotic chassis

Step 1:

Take a robotic chassis.

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Step 2:

Take the BO motor as shown in the diagram.

Step 3:

Take a M2.5 (25) screw to fit the BO motor on the chassis. Fit the motor in upward direction as shown in the figure. Here the last hole of the chassis are used to fit the motor.

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Note

Here kept the motor screw M2.5 (25) in the separate polyethene and also don’t mix it with other screw.

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Step 4

Fit the both wheel on the both motor shaft as shown in figure. Fix the motor with self tapping red wheel screw.robotStep 5 

Take the caster wheel and caster wheel strip as shown in the diagram.

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Step 6

Inset three M3 -10 screw into the caster wheel. Now fit the caster wheel into the caster wheel strip in the outward direction as shown in the figure.

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Step 7

Now fit the caster wheel strip on the middle position of the chassis as shown in the diagram by using two M3-10 screw.

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Now your robotic platform is ready to be used.

4. Breadboard Connection

 

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·         Give positive +5 volt supply in first row.

·         Connect the GND in the second row of the breadboard.

·         Connect + 5 volt  upper row with the below row to make below line +5 volt .

·         Connect the upper gnd line with the lower gnd line to make the below row gnd line.

·         Short the below middle rows as connect the +5 volt to +5volt line and gnd line with the gnd line.

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Construction of line follower robot on breadboard

·         Power Supply

·         Motor Driver

·         Logic sensor ( Comparator + Line sensor plate)

·         Inverter IC section

5. Power Supply Section

General Description

Power supply is used for to give power to the whole circuit assembly. The below component are used for to make power supply section.

Component list for power supply

Sr.No.

Component Name

Component list

1 DC jack 1
2 7805 voltage regulator IC 1
3 3 mm Led 1
4 Resistor  (220 ? ) (Red, Red, Black, Black ) 1

Explanation of component

Make the below connection for power supply as given in below image.

DC jack

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7805 Connection pin diagram

Sr .No

7805 Pin No

7805 Pin name

1

Pin 1

+12 volt (Given by battery)

2

Pin 2

Gnd

3

Pin3

+ 5 (output to give whole circuit )

By referring below images you can make the power supply circuit.

1.      Breadboard Image

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2.      Schematic Diagram for  power supply

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3.      Actual image of  power Supply

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Testing of power Supply Section

If  the led will be glow it means the power supply circuit connection is correct. and  now you can able to give power to whole the assembly.

6. Motor driver section

General Description

Now you have make a motor driver section which is used for to drive the motor. Here to drive the motor you have use L293D IC.

Component List for Motor Driver Section

Sr No

Component Name

1. L29D3 IC Section
2. One core wire

Designing of motor driver section

By referring below images and table  you can make and test the motor driver section.

L293D pin connection

Sr.No

L293 D pin

Supply voltage

1 Pin no 1 +5 volt
2 Pin no 9 +5 volt
3 Pin no 16 +5 volt
4 Pin no 8 +12 volt
5 Pin no 4 &  5 Gnd
6 Pin no 12 & 13 Gnd

Connection of Motor with L293D IC

Sr. No.

Output pins

Motor Wire

1 o/p1 First wire of  first  motor
2 o/p2 Second wire of first motor
3 o/p3 First wire of second motor
4 o/p4 Second wire of second motor

Breadboard Image

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Schematic image of motor driver section

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Actual  image of  motor driver section

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Give the below supply at input terminal of L293d IC to test the motor 

Sr.No. Pins Name Given supply
1 In1 +5
2 In2 Gnd
3 In3 +5
4 In4 Gnd

Note

·         Short 4  (gnd) and 5 (gnd) pin with the jumper. Jumper can be taken from the wire.

·         In the same way also short  pin no  12 (gnd) and 13(gnd) of the l293D IC.

Testing of motor driver section

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Step 1

Connect one wire of  first motor with the o/p1 pin of L293D IC. And second one is with second o/p2 of L293D IC.

The motor should be rotate in clockwise direction from your front side. If the motor rotate in anticlockwise direction than make it in clockwise direction by exchanging it’s wire with L293 o/p pins.

Step 2

Connect one wire of  second  motor with the o/p3 pin of L293D IC. And second one with second o/p4 of L293D IC.

Now the motor should be rotate in anticlockwise direction from your front side. If the motor rotate in clockwise direction than make it in anticlockwise direction by exchanging it’s wire with L293D o/p pins.

Now the chassis should be moves in the forward direction.

7. Logic Circuit

General Discription

This section consists of  two parts one is comparator section and another one is line sensor plate section.

Part 1

Comparator Section

Comparator LM324 IC  is used to generate logic which is used to drive the motor and led. Here the comparator IC is used to perform comparison between the reference voltage which is set at it’s non inverting input terminal and it’s inverting terminal voltage.

Component required to make logic circuit is as given below table.

Sr.No.

Component Name

Quantity

1. LM324 IC 1
2. 20 k preset (Metallic) 2
3. Led ( 3mm ) 2
4. 10 k ? ( Brown, Black ,Black, Red) 4

Component Explanation

20 k preset

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Here two potentiometer are used to set reference voltage at the non inverting terminal of pcb.

Note:

You can exchange the 5 volt and Gnd pin with each other.

LM 324 IC section

Sr.No

Pin no

Component Connection

1 1 (Output pin) Negative terminal of led
2 2 (Inverting pin) o/p  of  LDR sensor 1  from zero pcb
3 3 (Non inverting terminal) o/p pin of potentiometer 1
4 4  (vcc) +5 volt
5 11 GND
6 14(Output pin) Negative terminal of led
7 13 (Inverting pin) o/p  of  LDR sensor 2  from zero pcb
8 12 (Non inverting terminal) o/p pin of potentiometer 2

Make also below connection

·         Connect the positive terminal of both  led with the  one terminal of 10 k ? resistance  and another terminal of resistance with the +5 volt.

·         Connect the  one terminal of 10 k?  resistance with the  pin no 2 & pin no 13 of the LM324 ic and another terminal of both resistance with the + 5volt.

·         Also insert the 220 ? resistance in breadboard where it’s one terminal is connected to +5 volt and another will be connected with the Zero pcb +5 volt pin.

1.      Breadboard image of  logic section

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2. Schematic layout of logic section

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3.  Actual Image of comparator Section 

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Part 2

Sensor plate section

Sensor plate section consists of two LDR sensor and two led. Make the positive terminal of led and ldr are common and negative terminal of led and LDR are common.

Note

You can connect the LDR are sensor in any way in any direction. You can use ten core wire to make connection.

Component list for sensor plate

Sr.No.

Component Required

Quantity

1  3mm led 2
2 LDR 2
3 Ten core wire As per use

Note

Please make the connection on the zero pcb.

Breadboard image of sensor plate

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Schematic  layout for sensor plate.

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Actual image of  sensor plate  

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Calibration of line sensor 

Take a line sensor plate and make connection with the LM324 IC as given below.

·         Here one +5 volt pin of line sensor will be connected through the 220 ? resistance on breadboard and gnd pin will be connected through gnd pin on breadboard.

·         Two signal pin which are coming from two ldr sensor o/p (B & C) will be connected through lM324 pin ( 2 & 13 ).

·         Now take a white paper and stretch black tape on it.

·         Put the line sensor above the white sheet and perform calibration on it.

·         Set the both preset in this way that  both output led’s of LM324 IC  will becomes on  at the black surface and will becomes off on white surface as the sensor comes on the white sheet.

Note

You can set the preset by revolving it through screw driver.

·         Try the above step number of times until the both led will becomes on at the black surface and remains off at the white surface.

Sr.No.

Color

Logic generate at LM324 output pin

1

Black

0

2

White

1

Check your calibration step from below table as output generate on color.

Sr.no

LDR_sensor1

On

LDR_ sensor 2

On

Led1 of LM324 IC

Led 2 of LM324 IC

1

White

White

Off

Off

2

Black

White

On

Off

3

White

Black

Off

On

4

Black

Black

On

On

 

8. Inverting IC stage of (HD74LS04) IC

General Description

This section is used for to drive the motor by converting signal into the it’s invert form. If you have give 1 on it than it’s outcome will be 0 and if you have give 0 than it’s outcomes will be 1.

Component list

Sr.No.

Component Name

Quantity

1 HD74LS04  inverting IC 1

Make connection as given below in the table and as image given below

Short the inverter( HD74LS04) IC pin with each other as given in below table    

Sr. No.

Pin of inverting  IC

Pin of inverting  IC

1

Pin no 1

Pin no 5

2

Pin no 2

Pin no 3

3

Pin no 14

Pin no 9

4

Pin no 12

Pin no 11

Breadboard Image of inverter section

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Schematic image of inverter section

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Actual image of inverter section

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Fully connected circuit for line follower robot

First make the connection of inverting IC with the L293D IC

Inverter IC connection with L293D IC

Sr. No.

Pin of inverting IC

Pin of L293D IC

1 Pin no 4 Pin no 3
2 Pin no 6 Pin no 7
3 Pin no 10 Pin no 14
4 Pin no 8 Pin no 10

Inverter IC connection with comparator IC

Sr.No

Output pin of LM324 IC

Inverting pin ic no

1  LM 324 o/p pin 1 ( pin no 16) Pin no 1
2 LM 324 o/p pin 2  ( pin no 1) Pin no 13

9. Breadboard and Schematic Layout

Breadboard image of complete assembly

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Schematic layout of complete image

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Actual Image of Complete Circuit

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Now connect the Motor with the L293D as given below in table.

Connection of Motor with L293D IC

Sr. No.

Output pins

Motor Wire

1 o/p1 First wire of  first  motor
2 o/p2 Second wire of first motor
3 o/p3 First wire of second motor
4 o/p4 Second wire of second motor

Movement of robotic platform

Sr.No.

LDR_Sensor 1

LDR_Sensor 2

Output

1

White

White

Forward Movement

2

White

Black

Left /Right Movement

3

Black

White

Right/Left Movement

4

Black

Black

Backward Movement

 

10.Complete Assembly of line following robot

Now take the robotic platform to fit the zero line sensor PCB on the robotic platform.

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·         Take the M-60 screw and bolts to fit the zero pcb with the robotic platform.

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·         Take the line sensor zero pcb and make drill on it’s corner point.

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·         Now take a robotic platform and fit the zero pcb on the robotic platform with the M-60 screw driver. The sensors direction should be in downward direction.

·         Also fit the breadboard on the robotic platform. The complete assembly of the line robotic platform as given below.

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·         Also take a battery cell holder and put it on the robotic platform.

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