Obstacle Avoidance Robotic Vehicle

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Obstacle Avoidance Robotic
Vehicle

Abstract
 The main scope of project is to automatically changing the
direction of robotic vehicle as required whenever any obstacle
comes on its way.
 Here an ultrasonic sensor is used which detects the presence of
any obstacle and sends the signal to microcontroller which
changes the direction of the robot.

Introduction
 This particular robotic device is a combination of both
mechanical and electronics engineering.
 This system is made so that it can be used to detect and avoid
obstacles successfully.
 This robot will be just like an electronic car that keeps on
moving in straight line until something comes in its path that’s
when it decides to turns into some other direction so it
successfully avoids the obstacle.

Block diagram

Working of circuit diagram
 The project proposes robotic vehicle that has an intelligence built
in it such that it guides itself whenever an obstacle comes ahead
of it.
 This robotic vehicle is built, using a microcontroller of 8051
family. An ultrasonic sensor is used to detect any obstacle ahead
of it and sends a command to the microcontroller.
 Depending on the input signal received, the microcontroller
redirects the robot to move in an alternate direction by actuating
the motors interfaced to it through a motor driver IC.

Hardware requirements
 POWER SUPPLY
 MICROCONTROLLER 8052
 ULTRASONIC SENSOR
 MOTOR DRIVER IC

230 V AC
50 Hz
Bridge rectifier
Filter(470µf)
5v Regulator
5V DC
12V step down
transformer
Power supply

 8K Bytes of In-System Programmable (ISP) Flash
Memory.
 4.0V to 5.5V Operating Range.
Crystal Frequency 11.0592MHZ.
 Three-level Program Memory Lock.
 256 x 8-bit Internal RAM.
 32 Programmable I/O Lines.
 Three 16-bit Timer/Counters.
AT89S52
Micro controller

CPU
On-chip
RAM
On-chip
ROM for
program
code
4 I/O
Ports
Timer 0
Serial
PortOSC
Interrupt
Control
External interrupts
Timer 1
Timer/Count
er
Bus
Control
TxD RxDP0 P1 P2 P3
Address/Data
Counter
Inputs
Block diagram of MC

MC components explanation
ROM:
 A code of 4K memory is incorporated as on-chip ROM in 8051.
RAM:
 The 8051 microcontroller is composed of 128 bytes of internal RAM.
Interrupt Control:
 An event which is used to suspend or halt the normal program
execution for a temporary period of time in order to serve the
request of another program or hardware device is called an
interrupt.

Parallel Input/Output Ports:
PORT P0: When there is no external memory present, this port acts as
a general purpose input/output port.
PORT P1: This port is used for various interfacing activities.
PORT P2: This port can be used as a general purpose port when there
is no external memory but when external memory is present it works
in conjunction with PORT PO as an address bus.
PORT P3: PORT P3 behaves as a dedicated I/O port.

Address Bus:
 A bus is group of wires using which data transfer takes place
from one location to another within a system.
Timers and Counters:
 Synchronization among internal operations can be achieved with
the help of clock circuits which are responsible for generating
clock pulses.
 Internal operations can be synchronized using clock circuits
which produce clock pulses.

Pin diagram of 8052

8052 pin diagram explanation
Port 0(p0.0 to p0.7):
 It is 8-bit bi-directional I/O port. It is bit/ byte addressable. During
external memory access, it functions as multiplexed data and low-
order address bus AD0-AD7.
Port 1 (p1.0 to p1.7):
 It is 8-bit bi-directional I/O port. When logic '1' is written into port
latch then it works as input mode. It functions as simply I/O port
and it does not have any alternative function.

8052 pin diagram explanation
Port 2 (p2.0 to p2.7):
 It is 8-bit bi-directional I/O port. It is bit/ byte addressable.
Port 3(p3.0 to port 3.7):
 It is 8-bit I/O port. In an alternating function each pins can be used
as a special function I/O pin.
RESET:
 It is active high I/P signal. It should be maintained high for at least
two machine cycle while oscillator is running then 8051
microcontroller resets.

Ultrasonic sensor
 Ultrasonic sensors (also known as
transceivers) work on a principle similar
to radar or sonar which evaluate
attributes of a target by interpreting the
echoes from radio or sound waves
respectively.
 Ultrasonic sensors generate high
frequency sound waves and evaluate the
echo which is received back by the
sensor.

 Ultrasonic generators use piezoelectric materials such as zinc or
lead zirconium tartrates or quartz crystal.
 The material thickness decides the resonant frequency when
mounted and excited by electrodes attached on either side of it.
 The medical scanners used for abdomen or heart ultrasound are
designed at 2.5 MHz In this circuit, a 40 kHz transducer is used
for object detection in the air medium.
Ultrasonic receiver

Ultrasonic features
 Use for motion or distance sensing .
 Frequency: 40kHz ±1.0kHz.
 Aluminum case.
 Capacitance: 2000Pf ±20%.
 Transmitter: bandwidth 5.0kHz/100Db, sound pressure level.
112Db/40 ±1.0kHz

Motor driver 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.

Motor driver ic diagram

Operation of motor driver
 L293D has 2 set of arrangements where one set has input 1, input
2, output 1 and output 2 and other set has input 3, input 4,
output 3 and output 4, according to block diagram if pin no 2 & 7
are high then pin no 3 & 6 are also high.
 If enable 1 and pin number 2 are high leaving pin number 7 as
low then the motor rotates in forward direction.
 If enable 2 and pin number 10 are high leaving pin number 15 as
low then the motor rotates in forward direction.

Operation of motor driver
 If enable 1 and pin number 2 are low leaving pin number 7 as
high then the motor rotates in reverse direction.
 If enable 2 and pin number 15 are high leaving pin number 10
as low then the motor rotates in forward direction.

Operational diagram

Software requirements
 Keil an ARM Company makes C compilers, macro assemblers,
real-time kernels, debuggers, simulators, integrated
environments, evaluation boards, and emulators for
ARM7/ARM9/Cortex-M3, XC16x/C16x/ST10, 251, and 8051 MCU
families.
 Compilers are programs used to convert a High Level Language to
object code. Desktop compilers produce an output object code
for the underlying microprocessor, but not for other
microprocessors.

Applications
 Obstacle Detection for a Mining Vehicle.
 Driverless vehicles running along beams.
 Obstacle detecting system for a motor vehicle.
 Autonomous cleaning robot.

Future scope
 The future work includes the enhancement of the robot design
so that it can compute area of a room and plot it on the
computer.

Conclusion
 It gives on an opportunity to test his mechanical and electronics
and programming skills .
 Obstacle Avoidance Robotic Vehicle project also provides robot
construction experience to beginners.
 This technology has application everywhere from industry to
home appliances all that is required is to implement it correctly to
get the best out of it.

Obstacle Avoidance Robotic Vehicle

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