2. INTRODUCTION
Robotics is an interesting subject to discuss about and in this advanced world, Robots
are becoming a part of our life.
As strange as it might seem, there is no standard definition for a robot. However,
there are some essential characteristics that a robot must have and this might help
one to decide what is and what not a robot is. It will also help us to decide what
features are required to build into a machine before it can behave like a robot.
A robot has the essential characteristics:
1. Sensing : The robot should be able to sense its surroundings. Providing the robot with
the sensors such as light sensors (eyes), touch and pressure sensors (hands), chemical
sensors (nose), hearing and sonar sensors (ears), and taste sensors (tongue) will give
the robot awareness of its environment.
2. Movement : The robot needs to be able to move around its environment. Whether
rolling on wheels, walking on legs or propelling by thrusters a robot should be able to
move.
3. Energy : The robot needs to be able to power itself. A robot might be solar powered,
electrically powered, battery powered.
4. Intelligence : A robot needs some kind of "smarts." A programmer is the person who
gives the robot its 'smarts.' The robot will have to have some way to receive the
program so that it knows what it is to do.
3. So what is a robot?
It is a system that contains sensors, control systems, manipulators, power supplies and
software all working together to perform a task.
Designing, building, programming and testing a robots is a combination of physics,
mechanical engineering, electrical engineering, structural engineering, mathematics and
computing. In some cases biology, medicine, chemistry might also be involved.
A study of robotics means that it is an active involvement in all of these disciplines in a
deeply problem-posing problem-solving environment.
What is a line follower?
Line follower is a machine that can follow a path. 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.
What is the need to build a line follower?
Sensing a line and maneuvering the robot to stay on course, while constantly correcting
wrong moves using feedback mechanism forms a simple yet effective closed loop system.
The programmer gets the opportunity to ‘teach’ the robot how to follow the line thus
giving it a human-like property of responding to stimuli.
4.
5. MICROCONTROLLER(A
T89S52)
It has 40 pins and it is in
dual in package
It has 4 ports, 6 interrupts
and 2 timers
It has RAM of 128bytes and
ROM of 4KB
It is used for interfacing of
the input and output
modules
7. FEATURES
Compatible with MCS-51® Products
8K Bytes of In-System Programmable (ISP) Flash Memory
– Endurance: 1000 Write/Erase Cycles
4.0V to 5.5V Operating Range
Fully Static Operation: 0 Hz to 33 MHz
Three-level Program Memory Lock
256 x 8-bit Internal RAM
32 Programmable I/O Lines
Three 16-bit Timer/Counters
Eight Interrupt Sources
Full Duplex UART Serial Channel
Low-power Idle and Power-down Modes
Interrupt Recovery from Power-down Mode
8. WORKING PRINCIPLE
The Embedded Line following robot uses two motors to control rear wheels and the single front
wheel is free. It has 3-infrared sensors on the bottom for detection of black tracking tape. When the
middle sensor detects the black color, this sensor output is given to the comparator LM324. The
output of comparator compares this sensor output with a reference voltage and gives an output. The
output of comparator will be low when it receives an input from the sensor.
A simple logic has been used to implement this project. As it is known that black colour is capable of
absorbing the radiation and white colour or a bright colour reflects the radiation back. Here, 3 pairs
of IR TX and Rx are used. The robot uses these IR sensors to sense the line and the arrangement is
made such that sensors face the ground. The output from the sensors is an analog signal which
depends on the amount of light reflected back and this analog signal is given to the comparator to
produce 0s and 1s.
Internally we have an OTP (one time programmable) processor which is used to control
the rotation of the wheels. The rotation of these wheels depends up on the response from
the comparator. Let us assume that when a sensor is on the black line it reads 0 and
when it is on the bright surface it reads 1.
Here we can get three different cases, they are:
1. Straight direction
2. Right curve
3. Left curve
9. Straight direction:
It can be assumed that the robot moves in straight direction when the middle sensors
response is low and the remaining two sensors response is high. i.e., according to our
arrangement the middle sensor will always be on the line and as the line is black in
colour it will not reflect the emitted radiation back and the response of the sensor will be
low and the response of the remaining two sensors will be high as they will be on the
bright surface.
Right curve:
When a right curve is found on the line the responses will change i.e. the response of the
first sensor which is to the right will become low as that sensor will be facing the black
line and the remaining sensors response will be high. When this data is achieved, the
control of the wheels is changed i.e. the right wheel is held constant and the left wheel is
made to move freely until the response from the middle sensor becomes low. Then the
same process repeats again.
Left curve:
When a left curve is found on the line the response of the left most sensor will be changed
from high to low as the sensor will now face the black or the dark surface. Then the
control of the wheel changes i.e. by holding the left wheel constant and allowing the
right wheel to move freely until the middle sensor changes its response from high to low.
The same process continues for all the turns and the robot moves continuously until the
supply is removed.
10. Steps to follow the line (using single sensor):
-Start.
-Check for line.
-Line detected go right.
-Check for line.
-If no line turn left till line detected.
The arrangement of the sensors is shown in the figure.
11. LM 324
Wide gain bandwidth . : 1.3MHZ input common-
mode voltage range
Includes ground .largevoltage gain : 100DB .very
lowsupply current/ampli : 375MA .low input bias
current : 20NA low input offset voltage : 5mv max.
Low input offset current : 2NA wide power supply
range :
Single supply : +3v to +30v
Dual supplies : ±1.5v to ±15v
13. IR section
WHAT IS INFRARED?
Infrared is a energy radiation with a frequency
below our eyes sensitivity, so we cannot see it
Even that we can not "see" sound frequencies,
we know that it exist, we can listen them.
Even that we can not see or hear infrared, we
can feel it at our skin temperature sensors.
When you approach your hand to fire or warm
element, you will "feel" the heat, but you can't
see it. You can see the fire because it emits
other types of radiation, visible to your eyes, but
it also emits lots of infrared that you can only
feel in your skin
14. IR Transmitter, Receiver
IR TRANSMITTER
The IR LED emitting infrared light is put on in
the transmitting unit. To generate IR signal,
555 IC based astable multivibrator is used.
Infrared LED is driven through transistor BC
548.
IR RECEIVER
The TSOP17.. – Series are miniaturized
receivers for infrared remote control systems.
PIN diode and preamplifier are assembled on
lead frame, the epoxy package is designed as
IR filter
15. IR Emitter and IR phototransistor:
An infrared emitter is an LED made from gallium arsenide, which emits
near-infrared energy at about 880nm.
The infrared phototransistor acts as a transistor with the base voltage
determined by the amount of light hitting the transistor. Hence it acts as a
variable current source.
Greater amount of IR light cause greater currents to flow through the
collector-emitter leads.
16. IR Sensor
Features:
• Extra high radiant power and radiant
intensity
• High reliability
• Low forward voltage
• Suitable for high pulse current
operation
• Standard T-1¾ (∅ 5 mm) package
• Angle of half intensity ϕ = ± 17°
• Peak wavelength λp = 940 nm
• Good spectral matching to Si
photodetectors
17. Lead Acid Battery
Specifications
12V 1.3Ah sealed lead acid battery
1. CE and RoHs
2. high quality and relaibility
3. miantenance free
4. long life cycle
12V 1.3Ah sealed lead acid battery
General Features:
Sealed and maintenance free operation.
Non-Spillable construction design.
ABS containers and covers(UL94HB, UL94-
0)optional.
Safety valve installation for explosion proof.
High quality and high reliability.
Exceptional deep discharge recovery
performance.
Low self discharge characteristic.
Flexibility design for multiple install positions.
18. H-Bridge
Features:
600 mA Output Current Capability
Per Driver
Pulsed Current 1.2 A / Driver
Wide Supply Voltage Range: 4.5 V
to 36 V
Separate Input-Logic Supply
NE Package Designed for Heat
Sinking
Thermal Shutdown & Internal ESD
Protection
High-Noise-Immunity Inputs
19. DC Geared Motor
Technical Specifications:
•60RPM 12V DC motors with Metal Gearbox
•6mm shaft diameter
•Gearbox diameter 37 mm.
•Motor Diameter 28.5 mm
•Length 63 mm without shaft
•Shaft length 15mm
•300gm weight
•38kgcm torque
•No-load current = 800 mA(Max), Load current = upto 9.5
A(Max)
20. ADVANTAGES
Robot movement is automatic.
Fit and Forget system.
Used for long distance applications.
Defense applications.
Used in home, industrial automation.
Cost effective.
21. APPLICATIONS
Automated cars running on roads with embedded magnets.
Guidance system for industrial robots moving on shop floor etc.
Guidance system for industrial robots moving on shop floor etc.
Industrial applications
Home applications
22. CONCLUSION
In this project we have studied and implemented a
Line Following Robot using a Microcontroller for
blind people. The programming and interfacing of
microcontroller has been mastered during the
implementation. This device is designed to provide
with a greater advantage.
