25-08-2017, 09:32 PM
1461824289-ABSTACT1.docx (Size: 718.39 KB / Downloads: 10)
INTRODUCTION TO PROJECT
This project deals with a topic of much contemporary relevance. It proposes a unique and economical method for improving the safety of our level crossings .Road accidents at railway gate is a leading cause of death and injury worldwide. Surveys conducted by Indian Railway found that about 17% of total railway accidents in India is crossing accidents of which majority occurs at passive railway crossing . The operation of railway gates at level crossings is not so reliable nowadays. Primarily the road user has to wait a very long time before the arrival of train and even after the train is left. And secondly the chances of accidents that usually made by the carelessness of the road users or due to the time errors made by the gatekeepers is more. Here comes the importance of automatic railway gate control system.
In this project we detect the arrival of train and warn the road users about the arrival of train. If no obstacle is found a green signal is given for the train to pass, otherwise a red signal is given to slow down. After the obstacles are cleared, the gate is closed and train is passed .We will make sure that the train is passed and reopen the gate. The system deals with two things. Firstly, it deals with the reduction of time for which the gate is being kept closed. And secondly, to provide safety to the road users by reducing the accidents. In the automatic railway gate control system, at the level crossing the arrival of the train is detected by the sensor placed near to the gate. Hence, the time for which it is closed is less compared to the manually operated gates and also reduces the human labor.
The railroad industry’s own desire to maintain their ability to provide safe and secure transport of their customers hazardous materials, has introduced new challenges in rail security. Addressing these challenges is important, as railroads, and the efficient delivery of their cargo, play a vital role in the economy of the country.
The present project is designed to satisfy the security needs of the railways. This system provides the security in two ways: automatic gate opening/closing system at track crossing, signaling for the train driver. The automatic gate opening/closing system is provided with the IR sensors placed at a distance of few kilometers on the both sides from the crossing road. These sensors give the train reaching and leaving status to the embedded controller at the gate to which they are connected. The controller operates (open/close) the gate as per the received signal from the IR sensors.
The train driver always observes the signals placed beside the track. These signals are controlled from the control room. The green light denotes that the track is free and red light denotes the track is busy. These signals are controlled based on the train position which is sensed by the using the IR sensors placed along the track.
BLOCKDIAGRAM DESCRIPTION:
2.2.1. DESIGNING:
Since the main intension of this project is to design auditorium Control System. In order to fulfill this application there are few steps that has been performed i.e.
• Designing the power supply for the entire circuitry.
• Selection of microcontroller that suits our application.
• Selection of IR TX & IR RX.
• Selection of RELAYS.
• Complete studies of all the above points are useful to develop this project.
2.2.2.POWER SUPPLY SECTION:
In-order to work with any components basic requirement is power supply. In this section there is a requirement of two different voltage levels.
Those are
1) 5V DC power supply.
2) DC power supply.
Now the aim is to design the power supply section which converts 230V AC in to 5V DC. Since 230V AC is too high to reduce it to directly 5V DC, therefore we need a step-down transformer that reduces the line voltage to certain voltage that will help us to convert it in to a 5V DC. Considering the efficiency factor of the bridge rectifier, we came to a conclusion to choose a transformer, whose secondary voltage is 3 to 4 V higher than the required voltage i.e. 5V. For this application 0-9V transformers is used, since it is easily available in the market.
The output of the transformer is 9V AC; it feed to rectifier that converts AC to pulsating DC. As we all know that there are 3 kind of rectifiers that is
1) Half wave
2) Full wave and
3) Bridge rectifier
Here we short listed to use Bridge rectifier, because half wave rectifier has we less in efficiency. Even though the efficiency of full wave and bridge rectifier are the same, since there is no requirement for any negative voltage for our application, we gone with bridge rectifier.
Since the output voltage of the rectifier is pulsating DC, in order to convert it into pure DC we use a high value (1000UF/1500UF) of capacitor in parallel that acts as a filter. The most easy way to regulate this voltage is by using a 7805 voltage regulator, whose output voltage is constant 5V DC irrespective of any fluctuation in line voltage.
2.2.3. SELECTION OF MICROCONTROLLER:
As we know that there so many types of micro controller families that are available in the market. Those are
1. 8051 Family
2. AVR microcontroller Family
3. PIC microcontroller Family
4. ARM Family
Basic 8051 family is enough for our application; hence we are not concentrating on higher end controller families.
In order to fulfill our application basic that is AT89C51 controller is enough. But still we selected AT89S52 controller because of inbuilt ISP (in system programmer) option.
There are minimum six requirements for proper operation of microcontroller. Those are:
1) power supply section
2) pull-ups for ports (it is must for PORT 0)
3) Reset circuit
4) Crystal circuit
5) ISP circuit (for program dumping)
6) EA/VPP pin is connected to Vcc.
PORT0 is open collector that’s why we are using pull-up resistor which makes PORT0 as an I/O port. Reset circuit is used to reset the microcontroller. Crystal circuit is used for the microcontroller for timing pluses. In this project we are not using external memory that’s why EA/VPP pin in the microcontroller is connected to Vcc that indicates internal memory is used for this application.
2.2.4. SELECTION OF IR PAIR:
IR PAIRS are available in IR TX & IR RX. Here we are using it only for Detecting and sending information to the microcontroller. This is wireless applications, these IR TX is sending information up to 1 feet & this signal is received by IR RX.
2.2.5.SELECTION OF MOTOR:
Stepper Motor or dc motor is widely used in CNC machine drives , robots, and wherever an accurate positioning is required . In such applications, step angle , direction , operating modes( single coil or double coil), speed and position are important considerations. stepper motor is a simple dc motor with a permanent magnet rotor and a stator with armature consisting of coils. These coils produce a magnetic field when suitable current flows through them this field produces a torque in the rotor which makes it rotate. Well these are a little more complicated to control than the simple DC motors but these provide exact step wise rotation with an overall turn of 1.8 degrees / step . The step wise motion can be easily controlled by a stepper controller which is a simple circuit which takes digital logic and then uses it to turn the motor step wise .
CIRCUIT OPERATION
The structure of the railway gate control system contains a gate latch opener and IR Receivers are interfaced to the microcontroller. This having IR pairs for the purpose of getting the status of arrival and departure of the train from towards the gate and away from the gate.
The IR follows the line of sight propagation. Therefore IR TX continuously generating the light. IR RX continuously receiving the signal. Therefore RX getting the light when there is no disturbance in light transmission, at this movement IR RX gives low output(logic ‘0’). RX getting the no light when there is disturbance in light transmission, at this movement IR RX gives high output (logic ‘1’)
As soon as IR (arrival) receiver gets high gate closed. If IR (departure) receiver gets high gate opened. Therefore based on the status of the IR receiver, the micro controller close or open the gate.
2.5. INTRODUCTION TO EMBEDDED SYSTEMS:
Embedded systems are electronic devices that incorporate microprocessors with in their implementations. The main purposes of the microprocessors are to simplify the system design and provide flexibility. Having a microprocessor in the device helps in removing the bugs, making modifications, or adding new features are only matter of rewriting the software that controls the device. Or in other words embedded computer systems are electronic systems that include a microcomputer to perform a specific dedicated application. The computer is hidden inside these products. Embedded systems are ubiquitous. Every week millions of tiny computer chips come pouring out of factories finding their way into our everyday products.
Embedded systems are self-contained programs that are embedded within a piece of hardware. Whereas a regular computer has many different applications and software that can be applied to various tasks, embedded systems are usually set to a specific task that cannot be altered without physically manipulating the circuitry. Another way to think of an embeddedsystem is as a computer system that is created with optimal efficiency, thereby allowing it to complete specific functions as quickly as possible.
Embedded systems designers usually have a significant grasp of hardware technologies. They use specific programming languages and software to develop embedded systems and manipulate the equipment. When searching online, companies offer embedded systems development kits and other embedded systems tools for use by engineers and businesses.
Embedded systems technologies are usually fairly expensive due to the necessary development time and built in efficiencies, but they are also highly valued in specific industries. Smaller businesses may wish to hire a consultant to determine what sort of embedded systems will add value to their organization.
2.5.1. CHARACTERISTICS:
Two major areas of differences are cost and power consumption. Since many embedded systems are produced in tens of thousands to millions of units range, reducing cost is a major concern. Embedded systems often use a (relatively) slow processor and small memory size to minimize costs.
The slowness is not just clock speed. The whole architecture of the computer is often intentionally simplified to lower costs. For example, embedded systems often use peripherals controlled by synchronous serial interfaces, which are ten to hundreds of times slower than comparable peripherals used in PCs. Programs on an embedded system often run with real-time constraints with limited hardware resources: often there is no disk drive, operating system, keyboard or screen. A flash drive may replace rotating media, and a small keypad and LCD screen may be used instead of a PC's keyboard and screen.
Firmware is the name for software that is embedded in hardware devices, e.g. in one or more ROM/Flash memory IC chips. Embedded systems are routinely expected to maintain 100% reliability while running continuously for long periods, sometimes measured in years. Firmware is usually developed and tested too much harsher requirements than is general-purpose software, which can usually be easily restarted if a problem occurs.
2.6. INTRODUCTION TO MICROCONTROLLER
Microcontrollers as the name suggests are small controllers. They are like single chip computers that are often embedded into other systems to function as processing/controlling unit. For example the remote control you are using probably has microcontrollers inside that do decoding and other controlling functions. They are also used in automobiles, washing machines, microwave ovens, toys ... etc., where automation is needed.
Micro-controllers are useful to the extent that they communicate with other devices, such as sensors, motors, switches, keypads, displays, memory and even other micro-controllers. Many interface methods have been developed over the years to solve the complex problem of balancing circuit design criteria such as features, cost, size, weight, power consumption, reliability, availability, manufacturability. Many microcontroller designs typically mix multiple interfacing methods. In a very simplistic form, a micro-controller system can be viewed as a system that reads from (monitors) inputs, performs processing and writes to (controls) outputs.
Embedded system means the processor is embedded into the required application. An embedded product uses a microprocessor or microcontroller to do one task only. In an embedded system, there is only one application software that is typically burned into ROM. Example: printer, keyboard, video game player
Microprocessor - A single chip that contains the CPU or most of the computer
Microcontroller - A single chip used to control other devices
Microcontroller differs from a microprocessor in many ways. First and the most important is its functionality. In order for a microprocessor to be used, other components such as memory, or components for receiving and sending data must be added to it. In short that means that microprocessor is the very heart of the computer. On the other hand, microcontroller is designed to be all of that in one. No other external components are needed for its application because all necessary peripherals are already built into it. Thus, we save the time and space needed to construct devices.
2.6.1. FEATURES OF MICROCONTROLLER AT89S52:
8K Bytes of In-System Reprogrammable Flash Memory
Endurance: 1,000 Write/Erase Cycles
Fully Static Operation: 0 Hz to 24 MHz
256 x 8-bit Internal RAM
32 Programmable I/O Lines
Three 16-bit Timer/Counters
Eight Interrupt Sources
Programmable Serial Channel
Low-power Idle and Power-down Modes
ALE/PROG:
Address Latch Enable is an output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during flash programming. In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and may be used for external timing or clocking purposes. However, that one ALE pulse is skipped during each access to external data memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode.
PSEN
Program Store Enable is the read strobe to external program memory. When the AT89C52 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory.
EA/VPP:
External Access Enable (EA) must be strapped to GND in order to enable the device to fetch code from external pro-gram memory locations starting at 0000H up to FFH. However, if lock bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to VCC for internal program executions. This pin also receives the 12V programming enable voltage (VPP) during Flash programming when 12V programming is selected.
XTAL1:
Input to the inverting oscillator amplifier and input to the internal clock operating circuit.
XTAL2:It is an output from the inverting oscillator amplifier.
2.7. Power Supply
Power supply is a reference to a source of electrical power. A device or system that supplies electrical or other types of energy to an output load or group of loads is called a power supply unit or PSU. The term is most commonly applied to electrical energy supplies, less often to mechanical ones, and rarely to othersis this power supply section required to convert AC signal to DC signal and also to reduce the amplitude of the signal. The available voltage signal from the mains is 230V/50Hz which is an AC voltage, but the required is DC voltage (no frequency) with the amplitude of +5V and +12V for various applications.
In this section we have Transformer, Bridge rectifier, are connected serially and voltage regulators for +5V and +12V (7805 and 7812) via a capacitor (1000µF) in parallel are connected parallel as shown in the circuit diagram below. Each voltage regulator output is again is connected to the capacitors of values (100µF, 10µF, 1 µF, 0.1 µF) are connected parallel through which the corresponding output (+5V or +12V) are taken into consideration.
INFRARED TECHNOLOGY
3.1. WHAT IS INFRARED?
Technically known as "infrared radiation", infrared light is part of the electromagnetic spectrum located just below the red portion of normal visible light – the opposite end to ultraviolet. Although invisible, infrared follows the same principles as regular light and can be reflected or pass through transparent objects, such as glass. Infrared remote controls use this invisible light as a form of communications between themselves and home theater equipment, all of which have infrared receivers positioned on the front. Essentially, each time you press a button on a remote, a small infrared diode at the front of the remote beams out pulses of light at high speed to all of your equipment. When the equipment recognizes the signal as its own, it responds to the command.
The light our eyes see is but a small part of a broad spectrum of electromagnetic radiation. On the immediate high energy side of the visible spectrum lies the ultraviolet, and on the low energy side is the infrared. The portion of the infrared region most useful for analysis of organic compounds is not immediately adjacent to the visible spectrum, but is that having a wavelength range from 2,500 to 16,000 nm, with a corresponding frequency range from 1.9*1013 to 1.2*1014 Hz. (From http://hyperphysics.phy-astr.gsu.edu/hbase/ems3.html: the frequency of infrared ranges from 0.003 - 4 x 1014 Hz or about 300 gigahertz to 400 terahertz.).
Infrared imaging is used extensively for both military and civilian purposes. Military applications include target acquisition, surveillance, and night vision, homing and tracking. Non-military uses include thermal efficiency analysis, remote temperature sensing, short-ranged wireless communication, spectroscopy, and weather forecasting. Infrared astronomy uses sensor-equipped telescopes to penetrate dusty regions of space, such as molecular clouds; detect cool objects such as planets, and to view highly red-shifted objects from the early days of the universe
FEATURES:
• Wave length is 940 nm
• Chip material =GaAs with AL GaAs window
• Package type: T-1 3/4 (5mm lens diameter)
• Matched Photo sensor: QSD122/123/124
• Medium Emission Angle, 40°
• High Output Power
• Package material and color: Clear, untainted, plastic
3.1.3Emitter/Detector Alignment:
Good alignment of the emitter and detector is important for good operation, especially if the gap is large. This can be done with a piece of string stretched between and in line with LED and phototransistor. A length of dowel or stiff wire could be used to set the alignment. Another method that can be used for longer distances is a laser pointer shone through one of the mounting holes
For best results the height of the "beam" should be at coupler height and at an angle across the tracks. The emitter could also be mounted above the track with the phototransistor placed between the rails in locations such as hidden yards. Placing the emitter and detector at an angle would again be helpful.