Monday 11 February 2013

RAILWAY GATE CONTROL

RAILWAY GATE CONTROL  :::::






Description of the Project:-

Content-addressable memory (CAM) is a special type of computer Memory used in certain very high speed searching applications. It is also known as associative memory, associative storage, or associative array.

Content-addressable memory (CAM) is frequently used in applications,

such as lookup tables, databases, associative computing, and networking, that require high-speed searches due to its ability to improve application performance by using parallel comparison to reduce search time. Although the use of parallel comparison results in reduced search time, it also significantly increases power consumption. In this paper, we propose a Block-XOR approach to improve the efficiency of low power precomputation- based CAM (PB-CAM). Compared with the ones-count PB-CAM system, the experimental results show that our proposed approach can achieve on average 30% in power reduction and 32% in power performance reduction. The major contribution of this paper is that it presents practical proofs to verify that our proposed Block-XOR PB-CAM system can achieve greater power reduction without the need for a special CAM cell design. This implies that our approach is more flexible and adaptive for general designs

OBJECTIVE:

The aim of this project is to Automate unmanned railway gate using mechatronics.

Project Definition:

The objective of this project is to manage the control system of railway gate using the microcontroller. When train arrives at the sensing point alarm is triggered at the railway crossing point so that the people get intimation that gate is going to be closed. Then the control system activates and closes the gate on either side of the track. once the train crosses the other end control system automatically lifts the gate. For mechanical operation of the gates 1.8 step angle stepper motors are employed. Here we are using embedded controller built around the 8051 family (AT89C52) for the control according to the data pattern produced at the input port of the micro controller, the appropriate selected action will be taken.. The logic is produced by the program written in Embedded C language. The software program is written, by using the KEIL micro vision environment. The program written is then converted in HEX code after simulation and burned on to microcontroller using FLASH micro vision. 

WORKING METHODOLOGY:

Present project is designed using 8051 microcontroller to avoid railway accidents happening at unattended railway gates, if implemented in spirit. This project utilizes two powerful IR transmitters and two receivers; one pair of transmitter and receiver is fixed at up side (from where the train comes) at a level higher than a human being in exact alignment and similarly the other pair is fixed at down side of the train direction. Sensor activation time is so adjusted by calculating the time taken at a certain speed to cross at least one compartment of standard minimum size of the Indian railway. We have considered 5 seconds for this project. Sensors are fixed at 1km on both sides of the gate. We call the sensor along the train direction as ‘foreside sensor’ and the other as ‘after side sensor’. When foreside receiver gets activated, the gate motor is turned on in one direction and the gate is closed and stays closed until the train crosses the gate and reaches aft side sensors. When aft side receiver gets activated motor turns in opposite direction and gate opens and motor stops. Buzzer will immediately sound at the fore side receiver activation and gate will close after 5 seconds, so giving time to drivers to clear gate area in order to avoid trapping between the gates and stop sound after the train has crossed. 

GATE CONTROL

Railways being the cheapest mode of transportation are preferred over all the other means .When we go through the daily newspapers we come across many railway accidents occurring at unmanned railway crossings. This is mainly due to the carelessness in manual operations or lack of workers. We, in this project has come up with a solution for the same. Using simple electronic components we have tried to automate the control of railway gates. As a train approaches the railway crossing from either side, the sensors placed at a certain distance from the gate detects the approaching train and accordingly controls the operation of the gate. Also an indicator light has been provided to alert the motorists about the approaching train.

Introduction:

The objective of this project is to manage the control system of railway gate using the microcontroller. When train arrives at the sensing point alarm is triggered at the railway crossing point so that the people get intimation that gate is going to be closed. Then the control system activates and closes the gate on either side of the track. once the train crosses the other end control system automatically lifts the gate. For mechanical operation of the gates 1.8 step angle stepper motors are employed. Here we are using embedded controller built around the 8051 family (AT89C52) for the control according to the data pattern produced at the input port of the micro controller, the appropriate selected action will be taken.. The logic is produced by the program written in Embedded C language. The software program is written, by using the KEIL micro vision environment. The program written is then converted in HEX code after simulation and burned on to microcontroller using FLASH micro vision. 

AT89C51 Microcontroller

The Micro controller (AT89C51) is a low power; high performance CMOS 8-bit micro controller with 4K bytes of Flash programmable and erasable read only memory (PEROM). The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional non-volatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer, which provides a highly flexible and cost-effective solution to many embedded control applications. By using this controller the data inputs from the smart card is passed to the parallel port of the pc and accordingly the software responds. The IDE for writing the embedded program used is KEI L software.

Keil Micro vision Integrated Development Environment.

Keil Software development tools for the 8051 micro controller family support every level of developer from the professional applications engineer to the student just learning about embedded software development.The industry-standard Keil C Compilers, Macro Assemblers, Debuggers, Real-time Kernels, and Single-board Computers support ALL 8051-compatible derivatives and help you get your projects completed on schedule.

The source code is written in assembly language .It is saved as ASM file with an extension. A51.the ASM file is converted into hex file using keil software. Hex file is dumped into micro controller using LABTOOL software. At once the file is dumped and the ROM is burnt then it becomes an embedded one.

Step Motor Advantages

Step motors convert electrical energy into precise mechanical motion. These motors rotate a specific incremental distance per each step. The number of steps executed controls the degree of rotation of the motor’s shaft. This characteristic makes step motors excellent for positioning applications. For example, a 1.8° step motor executing 100 steps will rotate exactly 180° with some small amount of non-cumulative error. The speed of step execution controls the rate of motor rotation. A 1.8° step motor executing steps at a speed of 200 steps per second will rotate at exactly 1 revolution per second.

Step motors can be very accurately controlled in terms of how far and how fast they will rotate. The number of steps the motor executes is equal to the number of pulse commands it is given. A step motor will rotate a distance and at a rate that is proportional to the number and frequency of its pulse commands.

Step motors have several advantages over other types of motors. One of the most impressive is their ability to position very accurately. NMB’s standard step motors have an accuracy of +/-5%. The error does not accumulate from step to step. This means that a standard step motor can take a single step and travel 1.8° +/-0.09°. Then it can take one million steps and travel 1,800,000° +/-0.09°. This characteristic gives a step motor almost perfect repeatability. In motor terms, repeatability is the ability to return to a previously held position. A step motor can achieve the same target position, revolution after revolution.

COMPONENTS

The project consists of three main parts:

• 8051 microcontroller

• IR Transmitter

• IR Receiver

• Stepper Motor Circuit

• 8051 CONTROLLER

The I/O ports of the 8051 are expanded by connecting it to an 8255 chip. The 8255 is programmed as a simple I/O port for connection with devices such as LEDs, stepper motors and sensors. 

The following block diagram shows the various devices connected to the different ports of an 8255. The ports are each 8-bit and are named A, B and C. The individual ports of the 8255 can be programmed to be input or output, and can be changed dynamically. The control register is programmed in simple I/O mode with port A, port B and port C (upper) as output ports and port C (lower) as an input port.

IR CIRCUITS

This circuit has two stages: a transmitter unit and a receiver unit. The transmitter unit consists of an infrared LED and its associated circuitry.

IR TRANSMITTER

The IR LED emitting infrared light is put on in the transmitting unit. To generate IR signal, 555 IC based astable multivibrator is used. Infrared LED is driven through transistor BC 548. IC 555 is used to construct an astable multivibrator which has two quasi-stable states. It generates a square wave of frequency 38kHz and amplitude 5Volts. It is required to switch ‘ON’ the IR LED.

IR RECEIVER:

The receiver unit consists of a sensor and its associated circuitry. In receiver section, the first part is a sensor, which detects IR pulses transmitted by IR-LED. Whenever a train crosses the sensor, the output of IR sensor momentarily transits through a low state. As a result the monostable is triggered and a short pulse is applied to the port pin of the 8051 microcontroller. On receiving a pulse from the sensor circuit, the controller activates the circuitry required for closing and opening of the gates and for track switching. The IR receiver circuit is shown in the figure below.

STEP MOTOR ADVANTAGES

Step motors convert electrical energy into precise mechanical motion. These motors rotate a specific incremental distance per each step. The number of steps executed controls the degree of rotation of the motor’s shaft. This characteristic makes step motors excellent for positioning applications. For example, a 1.8° step motor executing 100 steps will rotate exactly 180° with some small amount of non-cumulative error. The speed of step execution controls the rate of motor rotation. A 1.8° step motor executing steps at a speed of 200 steps per second will rotate at exactly 1 revolution per second.

Step motors can be very accurately controlled in terms of how far and how fast they will rotate. The number of steps the motor executes is equal to the number of pulse commands it is given. A step motor will rotate a distance and at a rate that is proportional to the number and frequency of its pulse commands.

Step motors have several advantages over other types of motors. One of the most impressive is their ability to position very accurately. NMB’s standard step motors have an accuracy of +/-5%. The error does not accumulate from step to step. This means that a standard step motor can take a single step and travel 1.8° +/-0.09°. Then it can take one million steps and travel 1,800,000° +/-0.09°. This characteristic gives a step motor almost perfect repeatability. In motor terms, repeatability is the ability to return to a previously held position. A step motor can achieve the same target position, revolution after revolution.

EMBEDDED SYSTEMS

Introduction:

An Embedded system is a combination of computer hardware and software, and perhaps additional mechanical or other parts, designed to perform a specific function.

Embedded systems are usually a part of larger, complex system. Dedicated applications, designed to execute specific activities, are implemented and embedded in systems. These embedded applications are required to collaborate with the other components of an enclosed system. Embedded application components interact mostly with the non-human external environment. They continuously collect data from sensors or other computer components and process data within real-time constraints. Embedded systems are usually associated with dedicated hardware and specific software.

• Embedding an application into system

• Application and system are closely tied together

• Collaborative application

• Dedicated H/W and specific S/W

• Interaction with non-human external environment

• Real-time systems are embedded systems

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