TURRET MOUNTED LASER GUIDANCE SYSTEMExternal 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 lockedonto it .There are basically four methods of detecting an object. First is the manual Fly by wire detectionsystem 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 theradar emissions of an enemy vehicle and then locks the warhead onto the target. And the last is laser guidedmissile 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 ofthe 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 ofabsolute 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 afiring mechanism as well as two motor drivers. The laser is mounted on a shaft by identical stepper motorswhich 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 laserbeam .The laser guided missiles and bombs work on the principle of beam riding guidance. With thistechnique the enemy target is detected by cameras mounted on the vehicle. The vehicle emits a laser beamwhich is kept pointed at the target .The laser radiation bounces off the target and is scattered in alldirections. After the laser beam is locked onto the target, the missile is launched as close as possible on thetarget .The missile contains a laser seeker which detects the direction of the reflected laser radiation and thenaims the projectile towards the source. Our project involves in developing a prototype of the laser guided missile, concentrating intarget detection and „target locking‟ by laser. The targets are marked on a white sheet of paper. The targetscan be marked using any symbol, i.e a cross, a triangle etc and by any colour.The image of the target istaken by a single V.G.A camera, kept at a fixed distance from the screen. A snapshot of the screen is takenand 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 newpair of co-ordinates. The X axis movement and the Y axis movement of the turret are controlled byindividual stepper motors. It is then sent to a 80C51 microcontroller via the serial port of the computer. Thenew pair of co-ordinates represents the number of steps the motor has to move in the X and Y axis directionrespectively in order to reach the target.The overall block diagram of the system is shown in figure 1 and the setup shown in figure 2FEATURES: 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 .Thecomputer 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 microcontrollers. The programmer being used is supported by a Dos based software LAB TOOL. The Programmersoftware 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 aUSB .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. Arelay 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. Themotors were previously used in the 5 ¼ inch floppy drive .It has a step angle of 7.5”. It has one commonterminal and resistance between two windings is 50 Ω.It has a dimension of 4*3 cm and weighs around 600gms.The stepper motor controlling the X axis movement of the turret is 12V, 6 wire bipolar winding motor. Ithas six terminals, in which two terminal are common. The step angle of the motor is 7.5” and hasdimensions 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 UARTThe microcontroller board consists of the following blocks Serial communication block Motor Drive block LCD blockSerial 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 9pin 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 30mAwhich is not enough to drive a motor.ULN2803 chip is used which acts a buffer and boots up the signalsfrom 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 darkcolours.Presently, the distance between the camera and the screen is kept constant. The image of the screenis 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 outputconsists of a RX2 dimensional array where R is the number of targets to be detected. The target image isshown 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 usingstepper 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, thestep angle of the motors was reduced by programming it to run by 8 step sequence which is also called “halfstepping sequence”.Interfacing the laser with microcontroller.The commands to switch on, off and coming back to its initial position is given is given by themicrocontroller. 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 UVisionREFERENCES: 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”.
2D VIEW OF THE TURRET SETUP Figure 2 12V VV8 V0 UC P L 8 O N5 R 2 Y axis motor1 T 8 5V 0 1 P1 3 X axis motor Figure 3
5V RELAY PORT P380C51 LASER Figure 4 .asm file ASM51 .Lst file(It shows .obj file the errors in the It has the machine assmebly code level translation of the assembly file. RL51 51 The object file is linked with the 8051 instruction set OH .hex file is burnt in the 8051 Figure 5