Tuesday 28 February 2012
Wednesday 22 February 2012
AIR DEFENSE GUN
INTRODUCTION
As the semi-conductor technology
is experiencing rapid growth, human life gets complicated without “embedded
system”. Nowadays these new technologies are introduced in the equipments
engaged in the battlefield to improve the safety of soldiers and also to ensure
combat effectiveness. Our scope is to develop a mechanism to automatically
control the movement of the air defense gun mounted on the tank. To understand
our project better, let’s consider our indigenous tank ‘ARJUN’ designed by
CVRDE, DRDO. It consists of hull and turret. The latter is provided with three hatches .There are
four crew members namely loader, gunner,
driver and commander .The tank is equipped with three guns, namely main gun,
machine gun and air defense gun. Main gun uses FSAPDS and HESH as ammunition,
the coaxial 7.62mm PKT machine gun and a 12.7mm air defense machine gun. A
5.45mm AKS-74 assault rifle is carried on a storage rack.
Air
defense gun is mounted on the loader’s hatch in the turret of the tank and is
controlled by the loader .It is primarily used to attack low flying armored
vehicles. Presently the gunner has to expose himself to track the enemy vehicle
and attack the target and so he becomes vulnerable to external foes, added to
it he has to manually adjust the desired elevation and depression of the air
defense gun.
Our
project focuses on the safety of the gunner by employing embedded systems to
position the air defense gun without having the gunner exposed.
SCOPE
The scope of the project is to create a
conceptual model enabling power operated movement of air defense gun in place
of the existing manual operation.
PRESENT STATUS ON MBT ARJUN
Presently the air defense gun is maneuvered
manually both in azimuth and vertical planes. This entails operation of the air
defense gun by the loader in the hatch opened condition, exposing the loader to
the attack by the enemy. Also this manual operation will be a tiring activity.
BASIC REQUIREMENTS
The system should enable sighting of the target
through a sight, aiming the target in hatch closed condition by slewing and
elevating/ depressing anti-aircraft gun The system should enable the rotation
of loader’s hatch in azimuth plane both in anti-clockwise and clockwise
direction through 360 degree. The movement of air defense gun in the vertical
plane is from -10 degree to +70 degree. The system also requires automatic
stopping of gun movement if it attains the extreme positions in the vertical
plane.
BASIC BLOCK DIAGRAM OF AUTOMATIC LAYING OF AIR DEFENSE GUN
TECHNICAL DESCRIPTION
JOYSTICK
●
Joystick is an
input device consisting of a stick that pivots on a base and reports its angle
or direction to the device it is controlling. Joysticks are often used to
control video games, and usually have one or more push-buttons whose state can
also be read by the computer. A popular variation of the joystick used on
modern video game consoles is the analog stick.
●
The joystick
has been the principal flight control in the cockpit of many aircraft,
particularly military fast jets, where center stick or side-stick location may
be employed.
●
Joysticks are
also used for controlling machines such as cranes, trucks, underwater unmanned
vehicles, wheelchairs, surveillance cameras and zero turning radius lawn
mowers. Miniature finger-operated joysticks have been adopted as input devices
for smaller electronic equipment such as mobile phones.
MICROCONTROLLER
ATMEGA32
The AVR core combines a rich instruction set
with 32 general purpose working registers. All the32 registers are directly
connected to the Arithmetic Logic Unit (ALU), allowing two independent
registers to be accessed in one single instruction executed in one clock cycle.
The resulting architecture is more code efficient while achieving throughputs up
to ten times faster than conventional CISC microcontrollers .The ATmega32
provides the following features: 32K bytes of In-System Programmable Flash
Program memory with Read-While-Write capabilities, 1024 bytes EEPROM, 2K byte
SRAM, 32general purpose I/O lines, 32 general purpose working registers, a JTAG
interface for Boundaryscan ,On-chip Debugging support and programming, three
flexible Timer/Counters with compare models, Internal and External Interrupts,
a serial programmable USART, a byte oriented Two-wire Serial Interface, an
8-channel, 10-bit ADC with optional differential input stage with programmable
gain (TQFP package only), a programmable Watchdog Timer with Internal
Oscillator, an SPI serial port, and six software selectable power saving modes.
The Idle mode stops the CPU while allowing the USART, Two-wire interface, A/D
Converter, SRAM, Timer/Counters ,SPI port, and interrupt system to continue
functioning. The Power-down mode saves the register
contents but freezes the Oscillator, disabling all
other chip functions until the next External Interrupter Hardware Reset. In
Power-save mode, the Asynchronous Timer continues to run ,allowing the user to
maintain a timer base while the rest of the device is sleeping. The ADC Noise
Reduction mode stops the CPU and all I/O modules except Asynchronous Timer , to minimize switching noise during ADC
conversions. In Standby mode, the crystal/resonator Oscillator is running while
the rest of the device is sleeping. This allows very fast start-up combined with
low-power consumption. In Extended Standby mode, both the main Oscillator and
the Asynchronous Timer continue to run.
The device is manufactured using Atmel’s high
density nonvolatile memory technology. The On chip ISP Flash allows the program
memory to be reprogrammed in-system through an SPI serial interface, by a
conventional nonvolatile memory programmer, or by an On-chip Boot program
running on the AVR core. The boot program can use any interface to download the
application program in the Application Flash memory. Software in the Boot Flash
section will continue to run the Application Flash section is updated,
providing true Read-While-Write operation. By combining an 8-bit RISC CPU with
In-System Self-Programmable Flash on a monolithic chip ,the Atmel ATmega32 is a
powerful microcontroller that provides a highly-flexible and cost-effective
solution to many embedded control applications .The ATmega32 AVR is supported
with a full suite of program and system development tools including: C
compilers, macro assemblers, program debugger/simulators, in-circuit emulators
,and evaluation kits.
LCD DISPLAY
A liquid crystal display (LCD) is a thin, flat electronic visual display that uses the light modulating properties of liquid crystals (LCs). LCs do not emit light directly.
SPECIFICATION
Important factors to consider when evaluating an LCD monitor:
■
Resolution: The
horizontal and vertical screen size expressed in pixels (e.g., 1024×768).
Unlike CRT monitors, LCD monitors
have a native-supported resolution for best display effect.
■
Dot pitch: The distance
between the centers of two adjacent pixels. The smaller the dot pitch size, the
less granularity is present, resulting in a sharper image. Dot pitch may be the
same both vertically and horizontally, or different (less common).
■
Viewable size:
The size of an LCD panel measured on the diagonal (more specifically known as
active display area).
■
Response time: The minimum time
necessary to change a pixel's colour or brightness. Response time is also
divided into rise and fall time. For LCD monitors, this is measured in btb
(black to black) or gtg (gray to gray). These different types of measurements
make comparison difficult.
■
Input lag - a delay between the
moment monitor receives the image over display link and the moment the image is
displayed. Input lag is caused by internal digital processing such as image
scaling, noise reduction and details enhancement, as well as advanced
techniques like frame interpolation. Input lag can measure as high as 3-4
frames (in excess of 67 ms for a 60p/60i signal). Some monitors and TV
sets feature a special "gaming mode" which disables most internal
processing and sets the display to its native resolution.
■
Refresh rate: The number of times per
second in which the monitor draws the data it is being given. Since activated
LCD pixels do not flash on/off between frames, LCD monitors exhibit no
refresh-induced flicker, no matter how low the refresh rate.[3] High-end
LCD televisions now feature up to 240 Hz refresh rate, which allows
advanced digital processing to insert additional interpolated frames to smooth
up motion, especially with lower-frame rate 24p material like the Blu-ray disc. However, such high
refresh rates may not be supported by pixel response times, and additional
processing can introduce considerable input lag.
■
Colour support:
How many types of colours are supported (coll., more specifically known as colour gamut).
■
Brightness: The amount of
light emitted from the display (coll., more specifically known as luminance).
LIMIT SWITCH
In electronics, a switch is
an electrical component that can break
an electrical circuit, interrupting
the current or diverting
it from one conductor to another. The most familiar form of switch is a
manually operated electromechanical device
with one or more sets of electrical contacts. Each set of
contacts can be in one of two states: either 'closed' meaning the contacts are
touching and electricity can flow between them, or 'open', meaning the contacts
are separated and non conducting.
A switch may be directly manipulated by a human as a control signal to a
system, such as a computer keyboard button, or to control power flow in a
circuit, such as a light switch.
Automatically-operated switches can be used to control the motions of machines,
for example, to indicate that a garage door has reached its full open position
or that a machine tool is in a position to accept another work piece. Switches
may be operated by process variables such as pressure, temperature, flow,
current, voltage, and force, acting as sensors in a process
and used to automatically control a system. For example, a thermostat is an
automatically-operated switch used to control a heating process. A switch that
is operated by another electrical circuit is called a relay. Large
switches may be remotely operated by a motor drive mechanism. Some switches are
used to isolate electric power from a system, providing a visible point of isolation
that can be pad-locked if necessary to prevent accidental operation of a
machine during maintenance, or to prevent electric shock.
DRIVING STEPPER MOTORS WITH THE L293D
The L293D contains two H-bridges for driving small DC motors. It can
also be used to drive stepper motors because stepper motors are, in fact, two
(or more) coils being driven in a sequence, backwards and forwards. One L293D
can, in theory, drive one bi-polar 2 phase stepper motor.
TRIGGER
A trigger is a mechanism that actuates the firing sequence of firearms, or a power tool. Triggers almost universally consist of levers or buttons actuated by the index finger. Rare variations use the thumb to actuate the trigger.
Firearms use triggers to initiate the firing of a cartridge in the
firing chamber of the weapon. This is accomplished by actuating a striking
device through a combination of spring and kinetic energy operating
through a firing pin to strike and ignite the
primer.
MODE SELECTION: BURST MODE
In automatic firearms, burst mode or
burst fire is a firing mode enabling the shooter to fire a predetermined number
of rounds,
usually 2 or 3 rounds or 100+ on anti-aircraft weapons, with a single
pull of the trigger. This firing mode is commonly used in submachine guns, assault rifles and carbines The burst mode
is normally employed as an intermediate fire mode between semi-automatic and fully-automatic, although some
firearms lack a "full auto" capability and use a burst mode instead.
The number of rounds fired in a burst is almost universally determined by a cam mechanism that trips the
trigger mechanism for each shot in the burst. Some designs will terminate the
burst if the trigger is released before the burst is complete, while others
will reset the cam position, so the next burst will fire a full number of
rounds.
ADDITIONAL FEATURES
●
PC interface
with the circuit for future processes.
●
Updating and
displaying the number of bullets fired.
●
Using image
processing for targeting the gun with the hatch in closed position.
●
Use of advanced
motors for a better control of position.
●
Use of real
time cameras for tracking the movement of the air defence
gun.
●
PROPOSED ACTION PLAN
On finalization of the hardware the same will be
procured for testing and assembly. Necessary software also to be generated for
the mechanism to function
Monday 20 February 2012
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