TURRET MOUNTED

LASER GUIDANCE SYSTEM

External Guide: Mr. M.N. Rehman Mayur Sarode(0110402062)

Internal Guide:Mr. K Venugopal Vivek Ranjan(0110402062)

ABSTRACT:

In unmanned warfare it is necessary to detect and track the enemy target after which the warhead is locked

onto it .There are basically four methods of detecting an object. First is the manual 'Fly by wire' detection

system in which the operator manually adjusts the scope and fires the warhead. Second is the 'heat seeking '

missile systems which detects the heat signature emitted by the enemy vehicle .The third type detects the

radar emissions of an enemy vehicle and then locks the warhead onto the target. And the last is laser guided

missile which points the enemy target with a laser and then the locks the warhead on to the target.

We propose to make a Laser-Guided Turret which tracks a target using a camera, calculates the location of

the target in 2-D space, and communicates to a turret to aim and fire.

The PC handles all video processing algorithms. When calculations are finished, the number of

absolute steps needed to move is sent to the turret. Other commands to the laser include fire, stop, and reset .

The circuitry of the turret contains Atmel 80C51 which interprets the command and controls a

firing mechanism as well as two motor drivers. The laser is mounted on a shaft by identical stepper motors

which control the Y axis movement and a stepper motor which controls the X axis movement.

INTRODUCTION:

Laser guidance is a technique of guiding a warhead, a projectile or a vehicle to a target by means of laser

beam .The laser guided missiles and bombs work on the principle of beam riding guidance. With this

technique the enemy target is detected by cameras mounted on the vehicle. The vehicle emits a laser beam

which is kept pointed at the target .The laser radiation bounces off the target and is scattered in all

directions. After the laser beam is locked onto the target, the missile is launched as close as possible on the

target .The missile contains a laser seeker which detects the direction of the reflected laser radiation and then

aims the projectile towards the source.

Our project involves in developing a prototype of the laser guided missile, concentrating in

target detection and „target locking‟ by laser. The targets are marked on a white sheet of paper. The targets

can be marked using any symbol, i.e a cross, a triangle etc and by any colour.The image of the target is

taken by a single V.G.A camera, kept at a fixed distance from the screen. A snapshot of the screen is taken

and sent to a desktop computer via the USB cable. Using the image processing functions of matlab, the co-

ordinate of the target is generated. The actual co-ordinates are then scaled and offset is added to give new

pair of co-ordinates. The X axis movement and the Y axis movement of the turret are controlled by

individual stepper motors. It is then sent to a 80C51 microcontroller via the serial port of the computer. The

new pair of co-ordinates represents the number of steps the motor has to move in the X and Y axis direction

respectively in order to reach the target.

The overall block diagram of the system is shown in figure 1 and the setup shown in figure 2

FEATURES:

512 MB Ram,1.9 GHz computer with serial ports

80C51 micro-controller

Laser pointer

3 Stepper motors

VGA web camera

SPECIFICATIONS:

Software:

Matlab R2006 installed on a computer having a minimum RAM of 512mb and 1.9 Ghz Speed .The

computer should also have 9 pin COM port to connect the serial cable.

Dos based ASM51 assembler and RL51 linker to execute the assembly program written for micro

controllers.

The programmer being used is supported by a Dos based software LAB TOOL. The Programmer

software is invoked by the command LT48 at the command prompt.

The overall process is shown in figure 5.

Camera:

A normal VGA web camera is used for the project. The web camera is connected to the computer through a

USB .To run the Web camera in matlab, the win32 driver for the camera is installed in the system.

Laser :

The laser available in market is switched on by a mechanical switch which has a voltage rating of 4.5 volt. A

relay based electrical switch is made which is controlled by the microcontroller.

Motors:

Two stepper motors control the Y movement of the turret It is a 12V, 5 wire bipolar winding motor. The

motors were previously used in the 5 ¼ inch floppy drive .It has a step angle of 7.5”. It has one common

terminal and resistance between two windings is 50 Ω.It has a dimension of 4*3 cm and weighs around 600

gms.

The stepper motor controlling the X axis movement of the turret is 12V, 6 wire bipolar winding motor. It

has six terminals, in which two terminal are common. The step angle of the motor is 7.5” and has

dimensions 5.3*4 cm dimension.

Microcontroller Board:

The micro controller used is 80C51 micro controller is manufactured by atmel. It has the following features.

8051 Central Processing Unit

4k × 8 ROM (80C51)

128 × 8 RAM

Three 16-bit counter/timers

Full duplex serial channel

Boolean processor

Low voltage (2.7V to 5.5V@ 16MHz) operation

Memory addressing capability

– 64k ROM and 64k RAM

Power control modes:

– Clock can be stopped and resumed

– Idle mode

– Power-down mode

CMOS and TTL compatible

Three speed ranges at VCC = 5V

– 0 to 16MHz

– 0 to 33MHz

Dual Data Pointers

Second DPTR register

6 interrupt sources

Four 8-bit I/O ports

Full–duplex enhanced UART

The microcontroller board consists of the following blocks

Serial communication block

Motor Drive block

LCD block

Serial Communication block:

The serial communication work in negative logic. The receive and transmit signals from the Rx (10) and Tx

(11) have to converted into positive logic in the range of 5 to 12 Volt. This is done by the Max 232 chip A 9

pin female connector connects the board to the Com port of the computer.

Motor Drive block:

Port P1 is used to is to run stepper motors. The output pulses from a micro-controller are 5volt and 30mA

which is not enough to drive a motor.ULN2803 chip is used which acts a buffer and boots up the signals

from microcontrollers.

The motor connections are shown in figure 3.

The overall schematic of the board is shown in attach 1.

WORK COMPLETED:

Setting up of Screen and design of Turret:

The screen is a white background on which the targets to be detected are marked are marked with dark

colours.Presently, the distance between the camera and the screen is kept constant. The image of the screen

is captured in mat tab using a VGA Web camera.

The turret consist of a platform over which the three stepper motors are mounted as shown in the blueprint

(attach 2).

Code for detecting the target:

A test code is developed in Matlab to detect multiple targets. The algorithm is given below. To test the code;

an image of the target screen, made in Microsoft paint as shown in fig 2 is fed into the program. The output

consists of a RX2 dimensional array where R is the number of targets to be detected. The target image is

shown in figure 6.

Algorithm:

1. Ask the user the number of points to be detected.

2. Read the image which has the target marked(fig.2).It is saved as test2.jpg

3. Read the image which contains a unit target. This is done in order to specify the shape and size of the

target. It is saved as crosshair. jpg

4. Convert the above two images to gray scale.

5. Calculate the size of the both the images and store it in arrays

6. Search of 0 in the target image

7. If a zero is found then check whether the next portion of the array is same as the array in which the

crosshair image is stored.

8. If the above condition is true then display the central co-ordinates of the target.

9. Send each data to the serial port of the computer.

Assembling of the micro controller board

The clock frequency of the micro controller is 11.059 MHz. An external crystal oscillator gives the clock

signals. The components of the microcontroller are soldered on a PCB according to the schematic shown

in attach 2.

Establishing of serial communication between the computer and the micro

controller board

. To check whether data is being sent or being received by micro-controller, a small test code in

microcontroller continuously sends a string to the computer. The data being received by the computer

can be seen in the Hyperterminal, which is Communication software available in Windows. The sending

baud rate of the micro controller and the receiving baud rate of the computer should be equal (9600).

The reverse process is also done. The string received by the UC is transmitted again to the computer and

read in the hyper terminal.

Motor selection and driving them by microcontroller:

Servo motors and stepper motors are suitable for our project. Servo motors have high load torque (2 kgNm)

and are by a microcontroller by giving it pwm signals. But due to high cost of servo motors, we are using

stepper motors. The stepper motor was first run by 4 step sequence which is also called “Full Stepping”. The

step angle of the stepper motor was observed to be 7.5 .As we need precise movement of the motors, the

step angle of the motors was reduced by programming it to run by 8 step sequence which is also called “half

stepping sequence”.

Interfacing the laser with microcontroller.

The commands to switch on, off and coming back to its initial position is given is given by the

microcontroller. The connections are shown in figure 4.

WORK TO BE COMPLETED AND IMPROVEMENTS:

Improvising the test program to be used by Web camera

Improving the code and to incorporate stereoscopic image processing

Making the laser turret system real time

Developing C codes to program 8051 microcontroller using UVision

REFERENCES:

The 8051 microcontroller by Mazadi

The 80C51 microcontroller family architecture(data sheet)

An Ms project titled „laser targeted wireless turret‟ form USC university.

Dr. Jean-Yves Bouguet, “Stereo Triangulation in Matlab”.

Figure 1

2D VIEW OF THE TURRET SETUP

Figure 2

Figure 3

8

0

C

5

1

U

L

N

2

8

0

3

X axis motor

Y axis motor

P

O

R

T

P1

8

1

12V

VV

V

5V

Figure 4

Figure 5

.asm file

.obj file

It has the machine

level translation of the

assembly file.

.Lst file(It shows

the errors in the

assmebly code

ASM51

RL51

51

The object file is

linked with the 8051

instruction set

OH

.hex file is

burnt in the

8051

80C51

LASER

5V RELAY

PORT P3

Figure 6