Railway track detection using gsm

8/9/2019 Railway track detection using gsm

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CHAPTER 1

INTRODUCTION

Railway is lifeline of India and it is being the cheapest modes of

transportation are preferred over all other means of transportation. When we go

through the daily newspapers we come across many accidents in railroad

railings. Railroad-related accidents are more dangerous than other

transportation accidents in terms of severity and death rate etc. Therefore more

efforts are necessary for improving safety. Collisions with train are generally

catastrophic, in that the destructive forces of a train usually no match for any

other type of vehicle. Train collisions form a major catastrophe, as they cause

severe damage to life and property. Train collisions occur frequently eluding all

the latest technology.

1.1 PROJECT BACKGROUND

Railway safety is a crucial aspect of rail operation the world over.

Malfunctions resulting in accidents usually get wide media coverage even when

the railway is not at fault and give to rail transport, among the uninformed

public, an undeserved image of inefficiency often fueling calls for immediate

Fig1.1: Causalities in Train Accidents during 1995-96 to 2006-07


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reforms. This paper is aimed at helping the railway administrations concerned

to strengthen their safety culture and develop the monitoring tools required by

modern safety management. Railroad intersections are very unique, special,

potentially dangerous and yet unavoidable in the World. Here two different

entities with entirely different responsibilities, domains, performances come

together and converge for a single cause of providing a facility to the road user.

During the normal operation also, there is every possibility of accidents

occurring even with very little negligence in procedure and the result is of very

high risk. The potential for accidents is made higher as the railways control

only half the problem. The other half, meanwhile, cannot really be said to be

controlled by one entity, as even though traffic rules and road design standards

supposedly exist, the movements of road users are not organized and monitored

by one specific entity as rigidly as rail movements. The railway systems of Asia

and the Pacific are no exception to this. Each year, accidents at level crossings

not only cause fatalities or serious injuries to many thousands of road users and

railway passengers, but also impose a heavy financial burden in terms of

disruptions of railway and road services and damages to railway and road

vehicles and property. A very high number of these collisions are caused by the

negligence, incompetence or incapacity of road vehicle drivers, who by and

large operate their vehicles in environments in which safety consciousness is

practically non-existent. Since it is the railway which must bear the

responsibility for ensuring that it is protected from the transgressions by road

users (despite the fact that in many countries the law gives it priority of passage

over road users), it is the railway which also has to shoulder most of the

financial burden of providing this protection. Similarly, it is the railway, which

has most of the responsibility for educating road users on the safe use of its

level crossings. Notwithstanding this, it appears that in many regions, railways


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are ill-equipped to be in a position to monitor level crossing safety effectively

and to take both corrective and pro-active measures to improve the safety of

their level crossing installations.

In the rapidly flourishing country like ours, even though all the

latest technologies are there train collisions are occurring frequently. The

railway accidents are happening due to the carelessness in manual operations or

lack of workers. The other main reasons for the collisions of Train are: 1.Train

Derailment in curves and bends,2.Running Train collisions with the Standing

Train,3.Train Accidents in Slopes,4.Mis- signaling due to fog or Mist. There is

no fruitful steps have been taken so far in these areas. This paper deals about

one of the efficient methods to avoid train Collision and derailment. Also by

using simple electronic components we tried to automate the control of railway

gate in an embedded platform. The system has been implemented and

demonstrated by using vibration sensor and ZigBee with the help of

microcontroller.

1.2 SCOPE: To

• Review the present status of level-crossing accidents and train collisions.

• Present statistics, indicators, technology and problems relating to the

systems adopted for railway protection; in practice

• Analyze various alternative systems for train collision avoidance; and

• Make recommendations pertaining to the selection of cost-effective

protection systems.

1.3 METHODOLOGY:

The following analyses are considered:


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•

Evaluation of the requirements of a Safety Management Information

System which adequately addresses the needs of railway management for

information on train collision avoidance performance;

•

Review of the essential and effective safety, enhancements, measures and

priorities for railway security.

• Assessment of level crossing safety performance and safety measures

• Examination of Cost Benefit Analysis of investments on level crossing

safety enhancement;

• Review of the technical attributes and suitability of Networked Anti

Collision System (ACD) for level crossing protection system;

• 6. Recommendations and guidelines for adoption of networked ACD

Systems by railways.

1.4 ORGANISATION OF THE REPORT

In the following chapter we are going to discuss more about the literature

review in chapter 2, the proposed system in chapter 3, results, discussion and

conclusion of the system in chapter 4. At the end of the report the list of

references and related appendices are attached.

We start with the literature review about the railway security monitoring

system and the existing system. Then we discuss about the flow of the project

and the important components of the project development in chapter 3.Finally

we made the conclusion and future recommendations in chapter 4, follwed by

the references and appendices.


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CHAPTER 2

LITERATURE REVIEW

2.1 EXISTING SYSTEM

The existing conventional signaling system most of the times

relay on the oral communication through telephonic and telegraphic

conversations as input for the decision making in track allocation for trains.

There is large scope for miscommunication of the information or

communication gap due to the higher human interference in the system. This

miscommunication may lead to wrong allocation of the track for trains, which

ultimately leads to the train collision. The statistics in the developing countries

showing that 80% of worst collisions occurred so far is due to either human

error or incorrect decision making through miscommunication in signaling and

its implementation. IR sensors are also used to identify the cracks in the

railway. IR sensors have limitations due to the geographic nature of the tracks.

The Anti collision device system also is found to be ineffective as it is notconsidering any active inputs from existing Railway signaling system, and also

lacks two ways communication capability between the trains and the control

centers or stations. Later geographical sensors have also been used which

makes use of satellites for communication. But the system is costly and

complicated to implement.

At present laser proximity detector is used for collision avoidance, IR

sensors identifies the cracks in the railway track and gate control is done by

manual switch controlled gate. But there is no combined solution for collision

between trains, train derailment in curves and bends and the automatic control

of railway gate.


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2.2 PROPOSED SYSTEM

RAILWAY SECURITY MONITORING SYSTEM USING VIBRATION

SENSOR AND ZIGBEE

The proposed Train Anti Collision and Level Crossing Protection

System consists of a self-acting microcontroller and two way ZigBee based

data communication system which works round-the-clock to avert train

collisions and accidents at the level crosses. Thus enhances safety in train

operations by providing a NON-SIGNAL additional safety overlay over the

existing signaling system. The system operates without replacing any of the

existing signaling and nowhere affects the vital functioning of the present safety

systems deployed for train operations. The proposed system gets data from the

vibration sensor. The efficiency of the system is expected to be considerably

increased as the proposed system takes inputs from the sensor and also from the

level crossing gates. As more relevant data are included, it is expected that the

present system may assist loco drivers in averting accidents efficiently. As no

change is necessary to be made to the infrastructure of the existing system, the

cost of implementation of this system is also less. The system has been

designed and simulated using proteus real time simulation software.

2.3 GENERAL FEATURES

• Railway security and monitoring system mainly focus (i) Train collision

avoidance (ii) Derailment in curves and bends (iii) Railway gate control

• This system uses PIC 16F877A microcontroller, PIC 16F73

microcontroller, mini sense 100(v) vibration sensor, zig-bee transceiver,

and servo motor.

•

PIC 16F877A is an 8 bit microcontroller with 10 channel ADC.


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•

The vibration sensor is used to sense the vibration of the train.

• Servo motor is used for the gate control.

• Zig-Bee transceiver provides the communication between the base station

and the train side.

•

Lithium ion battery is used for giving power to the components.

• Regulator IC (LM 7805) used for providing constant 5v supply

• Transistor Tip 122 is used for switching applications.

2.4 BLOCK DIAGRAM

In our project the entire system can be classified into two systems. The

first system can be placed in the base station side and the second system can be

placed in the train side.

• The system in the base station consists,

Micro controller (PIC 16f877a), Vibration sensor, Servo motor, zig-bee

transceiver and necessary power supply conditions.

•

The system in the train side consists,Micro controller (PIC 16f73), zig-bee transceiver, Brake control system and

necessary power supply conditions.

The fundamental block diagram of base station side and train side are shown

below


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FUNDAMENTAL BLOCK DIAGRAM OF BASE STATION SIDE

Figure 2.1: Block diagram of base station side

FUNDAMENTAL BLOCK DIAGRAM OF TRAIN SIDE

Figure 2.2: Block diagram of train side

PIC MICRO CONTROLLER

(PIC 16F877A)

ZIGBEE

TRANSCEIVER

POWER

SUPPLY (+5V)

VIBRATION

SENSOR

SERVO

MOTOR

PIC MICRO CONTROLLER

(PIC 16F73)

BRAKECONTROL

ZIGBEE

TRANSCEIVER

POWER

SUPPLY (+5V)


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2.4.1 Block diagram description

The sensors sense the input and sends to the microcontroller, where it

responds and gives command to the particular component with predefined

algorithm. The time parameters are crucial which can be easily changed and

modified using Micro-controllers. Thus, this device would work in coherence

would help to reduce the train collisions

2.4.2 Block diagram components

PIC microcontroller

• The microcontroller employed in our project is PIC 16F877A and PIC

16f73.• The microcontroller is used for entire control.

Vibration sensor

• Sense the vibration of the train. According to the vibration it determines

the train is arriving or departure.

• It works based on piezoelectric effect. That means it converts mechanical

vibration of train into electric pulses.

• The vibration sensor used in our project is mini sense 100 vertical.

Zig-Bee transceiver

• Zig-Bee devices are often used in mesh network form to transmit data

over longer distances, passing data through intermediate devices to reach

more distant ones.

• Zig-Bee is a specification for a suite of high level communication

protocols

• The IEEE specification of Zig-Bee is IEEE 802.15.4.


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Servo motor

• It is the modified form of DC motor

• It consist DC motor, potentiometer, gearing system.

•

The servo motor works based on PWM switching

•

The main advantage of servo motor is precise control of angular position.


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CHAPTER 3

RAILWAY SECURITY SYSTEM

3.1 HARDWARE DESCRIPTION

3.1.1VIBRATION SENSOR

It uses piezoelectric effect to detect the vibrations in the rails due to the

arrival or departure of train and the direction of vibration indicate the arrival or

departure. This could sense the train’s position at roughly at 800 to 900 m

away. This input is fed to the microcontroller. This could help in avoiding

accidents between trains in slopes because the arrival of one train found out

using vibration sensor can be immediately sent to the Control Room and the

power supply can be switched off within 3 minutes so trains could be stopped

without colliding each other. Vibration or shock sensors are commonly used in

alarm systems to activate an alarm whenever the devices to which they are

attached are touched, moved, or otherwise vibrated. Commercial vibration

sensors use a piezoelectric ceramic strain transducer attached to a metallic proofmass in order to respond to an externally imposed acceleration. Piezoelectric

vibration sensors used for detecting vibration from various vibration sources are

generally classified into two large types, resonant type and no resonant type.

Vibration sensors are several types. Before selecting the vibration sensor

must consider five factors. 1)It’s measuring range, 2)frequency range,

3)accuracy,4) transverse sensitivity and 5)ambient conditions. The most

commonly used vibration sensor is minisense 100


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MINISENSE 100

The Minisense 100 is a low-cost cantilever-type vibration sensor loaded

by a mass to offer high sensitivity at low frequencies. The pins are designed for

easy installation and are solderable. Horizontal and vertical mounting options

are offered as well as a reduced height version. The active sensor area is

shielded for improved RFI/EMI rejection. Rugged, flexible PVDF sensing

element withstands high shock overload. Sensor has excellent linearity and

dynamic range, and may be used for detecting either continuous vibration or

impacts. The mass may be modified to obtain alternative frequency response

and sensitivity selection. It can be classified into two 1)minisense 100

vertical,2)minisense 100 horizontal .The vibration sensor used here is minisense

100 vertical

Circuit diagram

Figure 3.1:a)circuit diagram of vibration sensor b)minisense 100 vertical

MINISENSE 100 VERTICAL

Functional description

The MiniSense 100 acts as a cantilever-beam accelerometer. When the

beam is mounted horizontally, acceleration in the vertical plane creates bending

10MΩ PIEZO

GNDa) b)


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in the beam, due to the inertia of the mass at the tip of the beam. Strain in the

beam creates a piezoelectric response, which may be detected as a charge or

voltage output across the electrodes of the sensor. The sensor may be used to

detect either continuous or impulsive vibration or impacts. For excitation

frequencies below the resonant frequency of the sensor, the device produces a

linear output governed by the "baseline" sensitivity. The sensitivity at resonance

is significantly higher. Impacts containing high-frequency components will

excite the resonance frequency, as shown in the plot above (response of

MiniSense 100 to a single half-sine impulse at 100 Hz, of amplitude 0.9 g). The

ability of the sensor to detect low frequency motion is strongly influenced by

the external electrical circuit.

Electrical description

The MiniSense 100 behaves electrically as an “active” capacitor: it may

be modeled as a perfect voltage source (voltage proportional to applied

acceleration) in series with the quoted device capacitance. Any external input or

load resistance will form a high-pass filter, with a roll-off frequency as

tabulated above, or calculated from the formula f(c) = 1/(2_RC). The

impedance of the sensor is approximately 650 M ohm at 1 Hz. The active

sensor element is electrically shielded, although care should be taken in the

PCB design to keep unshielded traces as short as possible.

External R (Ω) LLF (Hz) Desired LLF (Hz) Required R (Ω)

10M 65 10 65M

100M 6.5 1 650M

1G 0.65 0.1 6.5G

Table 3.1: Lower limiting frequency (-3 dB roll-off)


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Off-axis sensitivity

The sensitivity of the Minisense 100 follows a cosine law, when rotated

horizontally around its axis, or vertically around its mid-point. At 90 degrees

rotation in either plane, both baseline sensitivity and sensitivity at resonance are

at a minimum. In theory, sensitivity should be zero in this condition. It is likely

that some sensitivity around the resonance frequency will still be observed – but

this may be unpredictable and is likely to be at least -16 dB with reference to

the on-axis response. Note that the sensitivity at 30 degrees rotation is -1.25 dB

(87% of on-axis response), at 60 degrees, it falls to -6 dB (50%).

The plots below show the change in sensitivity observed for either:

1) Rotation about major axis of sensing element, or

2) Rotation about mid-point of sensing element.

3.1.2 ZIGBEE

The name ZigBee refers to the waggle dance of honey bees after their

return to the beehive. It symbolizes the communication between nodes in a

mesh network. So it is called as networking protocol. The network components

are analogous to queen bee, drones and worker bees. It is also the technological

Standard Created for Control and Sensor Networks based on the IEEE 802.15.4

Standard created by the ZigBee Alliance.

Off axis response

Rotation angle

Figure 3.2: off axis response of vibration sensor


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ZigBee is a specification for a suite of high level communication

protocols using small, low-power digital radios based on an IEEE 802 standard

for personal area networks. In the IEEE 802.15.4 standard the 802 refers to

the network operations and technologies,15 refers to wireless networking and 4

refers to the low data rate or low power consumption.

Overview

It is used in embedded application for low data rates, low power

consumption and long battery life. ZigBee lets battery powered devices can

sleep for hours or even days, reducing battery use. The duty cycle of battery

powered nodes within a ZigBee network is designed to be very low, offering

even more energy efficiency and greater battery life. Once associated with a

network, a ZigBee node can wake up and communicate with other ZigBee

devices and return to sleep. It is the inexpensive small packet networks used for

Home Entertainment and for Controlling Wireless sensor networks. It is having

the physical range of about 10-100 meters and data rate of 250kbits/sec.

So it is best suited for periodic or intermittent data or a single signal

transmission from a sensor or input device. Applications include wireless light

switches, electrical meters with in-home-displays, traffic management systems,

and other consumer and industrial equipment that requires short-range wireless

transfer of data at relatively low rates. The technology defined by the ZigBee

specification is intended to be simpler and less expensive than other WPANs,

such as Bluetooth or Wi-Fi.

ZigBee devices are often used in mesh network form to transmit data

over longer distances, passing data through intermediate devices to reach more

distant ones. This allows ZigBee networks to be formed ad-hoc, with no


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centralized control or high-power transmitter/receiver able to reach all of the

devices. Any ZigBee device can be tasked with running the network. The

ZigBee network layer natively supports both star and tree typical networks, and

generic mesh networks.

Every network must have one coordinator device, tasked with its

creation, the control of its parameters and basic maintenance. Within star

networks, the coordinator must be the central node. Both trees and meshes

allow the use of ZigBee routers to extend communication at the network level.

The mesh network is having high reliability and extensive range. ZigBee

Operates in the Unlicensed ISM bands.ISM 2.4 GHz is Global Band at

250kbps, 868 MHz is European Band at 20kbps and 915 MHz is North

American Band at 40kbps.

It mainly operates in Personal Area Networks and device-to-device

networks. Here the connectivity is in between small packet devices. It is used

for the control of lights, switches, thermostats, appliances etc. The Low duty

cycle of ZigBee provide long battery life and Support for multiple network

topologies like star and mesh up to 65000 nodes on a network. The 128-bit

encryption standard provides secure connection. Collision can also be

avoided by using ZigBee.

History

ZigBee-style networks began to be conceived around 1998, when many

installers realized that both Wi-Fi and Bluetooth were going to be unsuitable

for many applications. In particular, many engineers saw a need for self-

organizing ad-hoc digital radio networks.


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The IEEE 802.15.4-2003 standard was completed in May 2003 and has

been superseded by the publication of IEEE 802.15.4-2006. In the summer of

2003, Philips Semiconductors, a major mesh network supporter, ceased the

investment. The ZigBee specifications were ratified on 14 December 2004. The

ZigBee Alliance announced availability of Specification 1.0 on 13 June 2005,

known as ZigBee 2004 Specification. In September 2006, ZigBee 2006

Specification is announced. In 2007, ZigBee PRO, the enhanced ZigBee

specification was finalized.

The first stack release is now called ZigBee 2004. The second stack

release is called ZigBee 2006, and mainly replaces the structure used in 2004

with a "cluster library". The 2004 stack is now more or less obsolete. ZigBee

2007, now the current stack release, contains two stack profiles, stack profile 1

(simply called ZigBee), for home and light commercial use, and stack profile 2

(called ZigBee PRO). ZigBee PRO offers more features, such as multi-casting,

many-to-one routing and high security with Symmetric-Key Key Exchange

(SKKE), while ZigBee (stack profile 1) offers a smaller footprint in RAM and

flash. Both offer full mesh networking and work with all ZigBee application

profiles.

ZigBee 2007 is fully backward compatible with ZigBee 2006 devices: A

ZigBee 2007 device may join and operate on a ZigBee 2006 network and vice

versa. Due to differences in routing options, ZigBee PRO devices must become

non-routing ZigBee End-Devices (ZEDs) on a ZigBee 2006 network, the same

as for ZigBee 2006 devices on a ZigBee 2007 network must become ZEDs on a

ZigBee PRO network. The applications running on those devices work the

same, regardless of the stack profile beneath them. The ZigBee 1.0 specification

was ratified on 14 December 2004 and is available to members of the ZigBee


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Alliance. Most recently, the ZigBee 2007 specification was posted on 30

October 2007. The first ZigBee Application Profile, Home Automation, was

announced 2 November 2007.

ZIGBEE DEVICE TYPES

ZigBee Co-coordinator (ZC): The most capable device, the Co-coordinator

forms the root of the network tree and might bridge to other networks. There is

exactly one ZigBee Co-coordinator in each network since it is the device that

started the network originally (the ZigBee Light Link specification also allows

operation without a ZigBee Co-coordinator, making it more usable for over-the-

shelf home products). It stores information about the network, including acting

as the Trust Center & repository for security keys.

ZigBee Router (ZR): As well as running an application function, a Router can

act as an intermediate router, passing on data from other devices

ZigBee End Device (ZED): Contains just enough functionality to talk to the

parent node (either the coordinator or a Router); it cannot relay data from other

devices. This relationship allows the node to be asleep a significant amount of

the time thereby giving long battery life. A ZED requires the least amount of

memory, and therefore can be less expensive to manufacture than a ZR or ZC

ZIGBEE ARCHITECHTURE

The architecture of Zigbee is closely related with OSI model. ZigBee

builds upon the physical layer and medium access control defined in IEEE

standard 802.15.4 (2003 version) for low-rate WPANs.


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Figure 3.4: zigbee architecture

The specification goes on to complete the standard by adding four main

components: network layer, application layer, ZigBee device objects (ZDOs)

and manufacturer-defined application objects which allow for customization

and favor total integration


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Besides adding two high-level network layers to the underlying

structure, the most significant improvement is the introduction of ZDOs. These

are responsible for a number of tasks, which include keeping of device roles,

management of requests to join a network, device discovery and security.

ZigBee is not intended to support power line networking but to interface

with it at least for smart metering and smart appliance purposes. Because

ZigBee nodes can go from sleep to active mode in 30 ms or less, the latency can

be low and devices can be responsive, particularly compared to Bluetooth

wake-up delays, which are typically around three seconds. Because ZigBee

nodes can sleep most of the time, average power consumption can be low,

resulting in long battery.

Physical layer: It contains electrical and physical specifications.

MAC layer: The channel access is primarily through CSMA/CA. It takes care

of transmitting data, scanning channels and encryption of data.

Network layer: Take care of network setup, device configuration, routing and

providing security.

Application layer: It is mainly used for end user software applications.

Advantages

•

Power saving: As a result of the short working period, low power

consumption of communication, and standby mode

• Reliability: Collision avoidance is adopted, with a special time slot

allocated for those communications that need fixed bandwidth so that

competition and conflict are avoided when transmitting data. The MAC


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layer adopts completely confirmed data transmission, that is, every data

packet sent must wait for the confirmation from the receiver

• Low cost of the modules: The ZigBee protocol is patent fee free

•

Short time delay: Typically 30 ms for device searching, 15 ms for

standby to activation, and 15 ms for channel access of active devices

• Large network capacity: One ZigBee network contains one master

device and maximum 254 slave devices. There can be as many as 100

ZigBee networks within one area

• Safety: ZigBee provides a data integrity check and authentication

function. AES-128 is adopted and at the same time each application canflexibly determine its safety property.

•

Long battery life: The battery life is high compared to any other

devices.

• Security: The data can be protected from any external interferences.

Disadvantages

• Short range

• Low complexity

• Low data speed.

Applications

• Home automation

• Wireless sensor networks

• Industrial control

•

Embedded sensing

• Medical data collection


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•

Smoke and intruder warning

• Building automation

• Smart Energy 1.0

•

Telecommunication Services

•

Health Care

• Remote Control

• Light link

3.1.3 MICROCONTROLLER:

Circumstances that we find ourselves in today in the field of

microcontrollers had their beginnings in the development of technology of

integrated circuits. This development has made it possible to store hundreds of

thousands of transistors into one chip. That was a prerequisite for production of

microcontrollers, and the first computers were made by adding external

peripherals such as memory, input-output lines, timers and other. Further

increasing of the volume of the package resulted in creation integrated circuits.

These integrated circuits contained both processor and peripheral. That is how

the first chip containing a microcomputer, or what would later be known as a

microcontroller came about

A computer-on-a-chip is a variation of a microprocessor, which

combines the processor core (CPU), some memory, and I/O (input/output) lines,

all on one chip. The computer-on-a-chip is called the microcomputer whose

proper meaning is a computer using a (number of) microprocessor as its CPUs,

while the concept of the microcomputer is known to be a microcontroller. A

microcontroller can be viewed as a set of digital logic circuits integrated on a

single silicon chip. This chip is used for only specific applications.


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Advantages of micro controller

A designer will use a Microcontroller to

1. Gather input from various sensors

2. Process this input into a set of actions

3. Use the output mechanisms on the Microcontroller to do something useful

4. RAM and ROM are inbuilt in the MC.

5. Multi machine control is possible simultaneously.

6. ROM, EPROM, [EEPROM] or Flash memory for program and operating

parameter storage.

Examples:

8051, 89C51 (ATMAL), PIC (Microchip), Motorola (Motorola), ARM

Processor,

PIC MICROCONTROLLER

Features

A PIC microcontroller is an amazingly powerful fully featured processorwith internal RAM, EEROM FLASH memory and peripherals. One of the

smallest ones occupies the space of a 555 timer but has a 10bit ADC, 1k of

memory, 2 timers; high current I/O ports a comparator a watch dog timer.

PIC 16F877A

The microcontroller unit used here is a PIC16f877A .The core controller

is a mid-range family having a built-in SPI master. 16F877A have enough I/O

lines for current need. It is capable of initiating all intersystem communications.

The master controller controls each functions of the system with a supporting

device. Also responsible for reception of commands from the host and taking

necessary actions. PIC16F877A is an 8-bit, fully static,


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EPROM/EPROM/ROM-based CMOS microcontroller. It employs RISC

architecture with only 35 word/single cycle instructions. All these instructions

are single cycle (1ms) expect for program branches which takes two cycles. The

PIC16f877A products are supported by a full featured macro assembler, a

software simulator, „C‟ compiler etc.

The PIC16F887 features 256 bytes of EEPROM data memory, self

programming, an ICD, 2 Comparators, 14 channels of 10-bit Analog-to-Digital

(A/D) converter, 1 capture/compare/PWM and 1 Enhanced

capture/compare/PWM functions, a synchronous serial port that can be

configured as either 3-wire Serial Peripheral Interface (SPI™) or the 2-wireInter-Integrated Circuit (I²C™) bus and an Enhanced Universal Asynchronous

Receiver Transmitter (EUSART). All of these features make it ideal for more

advanced level A/D applications in automotive, industrial, appliances or

consumer applications.

Features:

•

High performance RISC CPU

• Only 35 single word instructions to learn

• All single cycle instructions except for program branches which are two

cycle

• Operating speed: DC - 20 MHz clock input DC - 200 ns instruction cycle

• Up to 8K x 14 words of FLASH Program Memory, Up to 368 x 8 bytes

of Data up to Memory (RAM) 256 x 8 bytes of EEPROM Data Memory

•

Pin out compatible to the PIC16C73B/74B/76/77

• Interrupt capability (up to 14 sources)

• Eight level deep hardware stack

• Programmable code protection


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•

Power saving SLEEP mode

• Selectable oscillator options

•

Low power, high speed CMOS FLASH/EEPROM technology

•

Fully static design

• In-Circuit Serial Programming (ICSP) via two pins

• Single 5V In-Circuit Serial Programming capability

• In-Circuit Debugging via two pins

• Processor read/write access to program memory

• Wide operating voltage range: 2.0V to 5.5V

• High Sink/Source Current: 25 mA

•

Commercial, Industrial and Extended temperature ranges

•

Low-power consumption: - < 0.6 mA typical @ 3V, 4 MHz - 20 µA

typical @ 3V, 32 kHz - < 1 µA typical standby current

Peripheral features:

•

Timer0: 8-bit timer/counter with 8-bit prescaler

•

Timer1: 16-bit timer/counter with prescaler, can be incremented during

SLEEP via external crystal/clock

•

Timer2: 8-bit timer/counter with 8-bit period register, prescaler and post

scalar


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•

Two Capture, Compare, PWM modules - Capture is 16-bit, max.

Resolution is 12.5 ns - Compare is 16-bit, max. Resolution is 200 ns -

PWM max. Resolution is 10-bit

• 10-bit multi-channel Analog-to-Digital converter

• Synchronous Serial Port (SSP) with SPI (Master mode) and

I2C(Master/Slave)

• Universal Synchronous Asynchronous Receiver Transmitter

(USART/SCI) with 9-bit address detection.

Analog features:

•

10-bit, up to 8-channel Analog-to-Digital Converter (A/D)

• Brown-out Reset (BOR)

• Analog Comparator module with: -Two analog comparators -

Programmable on-chip voltage reference (VREF) module -Programmable

input multiplexing from device inputs and internal voltage reference -

Comparator outputs are externally accessible

Special microcontroller features:

•

100,000 erase/write cycle Enhanced Flash program memory typical

• 1,000,000 erase/write cycle Data EEPROM memory typical

• Data EEPROM Retention > 40 years

• Self-reprogrammable under software control

•

In-Circuit Serial Programming™ (ICSP™) via two pins

• Single-supply 5V In-Circuit Serial Programming

• Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable

operation Programmable code protection

•

Power saving Sleep mode


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•

Selectable oscillat

• In-Circuit Debug (

Figure

r options

ICD) via two pins

3.5: Block diagram of PIC 16F877A


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Hardware features

There are three memory blocks in each of the PIC16F87XA devices.

The program memory and data memory have separate buses so that concurrent

access can occur. The Special Function Registers are registers used by the CPU

and peripheral modules for controlling the desired operation of the device.

These registers are implemented as static RAM. Some pins for these I/O ports

are multiplexed with an alternate function for the peripheral features on the

device. In general, when a peripheral is enabled, that pin may not be used as a

general purpose I/O pin. The Master Synchronous Serial Port (MSSP) module

is a serial interface, useful for communicating with other peripheral or

microcontroller devices. These peripheral devices may be serial EEPROMs,

shift registers, display drivers, A/D converters, etc. The MSSP module can

operate in one of two modes. The Universal Synchronous Asynchronous

Receiver Transmitter (USART) module is one of the two serial I/O modules.

(USART is also known as a Serial Communications Interface or SCI.) The

USART can be configured as a full-duplex asynchronous system that can

communicate with peripheral devices, such as CRT terminals and personal

computers, or it can be configured as a half-duplex synchronous system that can

communicate with peripheral devices, such as A/D or D/A integrated circuits,

serial EEPROMs, etc. The Analog-to-Digital (A/D) Converter module has five

inputs for the 28-pin devices and eight for the 40/44-pin devices. The

conversion of an analog input signal results in a corresponding 10-bit digital

number. The A/D module has high and low-voltage reference input that is

software selectable to some combination of VDD, VSS, RA2 or RA3. The A/D

converter has a unique feature of being able to operate while the device is in

Sleep mode. To operate in Sleep, the A/D clock must be derived from the A/D’s

internal RC oscillator. The comparator module contains two analog


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comparators. The inputs to the comparators are multiplexed with I/O port pins

RA0 through RA3, while the outputs are multiplexed to pins RA4 and RA5.

All PIC16F87XA devices have a host of features intended to maximize

system reliability, minimize cost through elimination of external components,

provide power saving operating modes and offer code protection.

Memory organization

There are three memory blocks in each of the PIC16F87X MCUs. The

Program Memory and Data Memory have separate buses so that concurrent

access can occur.

Program memory organization

The PIC16F87X devices have a 13-bit program counter capable of

addressing an 8K x 14 program memory space. The PIC16F877/876 devices

have 8K x 14 words of FLASH program memory, and the PIC16F873/874

devices have 4K x 14. Accessing a location above the physically implemented

address will cause a wraparound. The RESET vector is at 0000h and the

interrupt vector is at 0004h.

Data memory organization

The data memory is partitioned into multiple banks which contain the

General Purpose Registers and the Special Function Registers. Bits RP1

(STATUS) and RP0 (STATUS) are the bank select bits. Each bank

extends up to 7Fh (128 bytes). The lower locations of each bank are reserved

for the Special Function Registers. Above the Special Function Registers are

General Purpose Registers, implemented as static RAM. All implemented banks

contain Special Function Registers. Some frequently used Special Function


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RB7/PGD. The alternate functions of these pins are described in “Special

Features of the CPU”. Each of the PORTB pins has a weak internal pull-up. A

single control bit can turn on all the pull-ups. This is performed by clearing bit

RBPU (OPTION_REG). The weak pull-up is automatically turned off when

the port pin is configured as an output. The pull-ups are disabled on a Power-on

Reset.

PORTC is an 8-bit wide, bidirectional port. The corresponding data

direction register is TRISC. Setting a TRISC bit (= 1) will make the

corresponding PORTC pin an input (i.e., put the corresponding output driver in

a High-Impedance mode). Clearing a TRISC bit (= 0) will make the

corresponding PORTC pin an output (i.e., put the contents of the output latch

on the selected pin). PORTC is multiplexed with several peripheral functions.

Figure 3.6: Pin details of PIC 16F877A


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PORTC pins have Schmitt Trigger input buffers. When the I2C module is

enabled, the PORTC pins can be configured with normal I2C levels, or

with SMBus levels, by using the CKE bit (SSPSTAT). When enabling

peripheral functions, care should be taken in defining TRIS bits for each

PORTC pin. Some peripherals override the TRIS bit to make a pin an output,

while other peripherals override the TRIS bit to make a pin an input. Since the

TRIS bit override is in effect while the peripheral is enabled, read-modify-write

instructions (BSF, BCF, XORWF) with TRISC as the destination, should be

avoided. The user should refer to the corresponding peripheral section for the

correct TRIS bit settings.

PORTD is an 8-bit port with Schmitt Trigger input buffers. Each pin is

individually configurable as an input or output. PORTD can be configured as an

8-bit wide microprocessor port (Parallel Slave Port) by setting control bit,

PSPMODE (TRISE). In this mode, the input buffers are TTL.

PORTE has three pins (RE0/RD/AN5, RE1/WR/AN6 and RE2/CS/AN7)

which are individually configurable as inputs or outputs. These pins have

Schmitt Trigger input buffers. The PORTE pins become the I/O control inputs

for the microprocessor port when bit PSPMODE (TRISE) is set. In this

mode, the user must make certain that the TRISE bits are set and that the

pins are configured as digital inputs. Also, ensure that ADCON1 is configured

for digital I/O. In this mode, the input buffers are TTL. Register 4-1 shows the

TRISE register which also controls the Parallel Slave Port operation. PORTE

pins are multiplexed with analog inputs. When selected for analog input, these

pins will read as „0‟s. TRISE controls the direction of the RE pins, even when

they are being used as analog inputs. The user must make sure to keep the pins


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configured as inputs when using them as analog inputs. The system has two

interconnected modules as its working elements.

PIC16F73

This powerful yet easy-to-program (only 35 single word instructions)

CMOS FLASH-based 8-bit microcontroller packs Microchip's powerful PIC®

architecture into a 28 pin package. The PIC16F73 features operating frequency

of 20MHz , 8-bit Analog-to-Digital Module, 2 capture/compare/PWM module

Serial Communications using SSP, USART,11 interrupts, Synchronous Serial

Port (SSP) with SPI, Master mode) and I2C (Slave), Universal Synchronous

Asynchronous Receiver Transmitter (USART/SCI), Parallel Slave Port (PSP),

Programmable code protection , Selectable oscillator options, In-Circuit Serial

Programming (ICSP)

General Features

•

High performance RISC CPU

•

Up to 8K x 14 words of FLASH Program Memory

• Up to 368 x 8 bytes of Data Memory (RAM)

• Timer0: 8-bit timer/counter with 8-bit prescaler

• Timer1: 16-bit timer/counter with prescaler can be incremented during



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Figure 3.7: Block diagram of PIC16F73


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•

Timer2: 8-bit timer/counter with 8-bit register, prescaler and postscaler

• Two Capture, Compare, PWM modules

- Capture is 16-bit, max. Resolution is 12.5 ns

- Compare is 16-bit, max. Resolution is 200 ns

- PWM max. Resolution is 10-bit

Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable

operation.

Peripheral Features:

• Timer0: 8-bit timer/counter with 8-bit prescaler

• Timer1: 16-bit timer/counter with prescaler, can be incremented during


• Timer2: 8-bit timer/counter with 8-bit period register, prescaler and

postscaler

•

Two Capture, Compare, PWM modules

- Capture is 16-bit, max. Resolution is 12.5 ns

-

Compare is 16-bit, max. Resolution is 200 ns

-

PWM max. Resolution is 10-bit

•

8-bit, up to 8-channel Analog-to-Digital converter

• Synchronous Serial Port (SSP) with SPI (Master mode) and I2C

(Slave)

• Universal Synchronous Asynchronous Receiver Transmitter

(USART/SCI)

• Parallel Slave Port (PSP), 8-bits wide with external RD, WR and CS

controls (40/44-pin only)

• Brown-out detection circuitry for Brown-out Reset (BOR)


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CMOS Technology:

• Low power, high speed CMOS FLASH technology

• Fully static design

•

Wide operating voltage range: 2.0V to 5.5V

•

High Sink/Source Current: 25 mA

• Low power consumption:

-

< 2 mA typical @ 5V, 4 MHz

-

20 µA typical @ 3V, 32 kHz

- < 1 µA typical standby current

PINDETAILS

The pins that are used in this system,

MCLR/VPP: Master Clear (input) or programming voltage (output

• MCLR: Master Clear (Reset) input. This pin is an active low RESET to

the device.

Figure 3.8: Block diagram of PIC16F73


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•

VPP: Programming voltage input.

VSS: Ground reference for logic and I/O pins.

Osc1: Oscillator crystal input or external clock source input. ST buffer when

configured in RC mode. Otherwise CMOS.

OSC2: Oscillator crystal output. Connects to crystal or resonator in Crystal

Oscillator mode

RC4: Digital I/O.

RC5: Digital I/O.

RC6: Digital I/O.

RC7: Digital I/O.VDD: Positive supply for logic and I/O pins.

RB0: Digital I/O.

3.1.4 SERVOMOTOR

A servomotor is a rotary actuator that allows for precise control of

angular position. It consists of a motor coupled to a sensor for position

feedback, through a reduction gearbox. It also requires a relatively sophisticated

controller, often a dedicated module designed specifically for use with

servomotors. Servomotors are used in applications such as robotics, CNC

machinery or automated manufacturing. It is the modified form of DC motor.

As the name suggests, a servomotor is a servomechanism. More

specifically, it is a closed-loop servomechanism that uses position feedback to

control its motion and final position. The input to its control is some signal,

either analogue or digital, representing the position commanded for the output

shaft.


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The motor is paired with some type of encoder to provide position and

speed feedback. In the simplest case, only the position is measured. The

measured position of the output is compared to the command position, the

external input to the controller. If the output position differs from that required,

an error signal is generated which then causes the motor to rotate in either

direction, as needed to bring the output shaft to the appropriate position. As the

positions approach, the error signal reduces to zero and the motor stops.

The very simplest servomotors use position-only sensing via a

potentiometer and bang-bang control of their motor; the motor always rotates at

full speed (or is stopped). This type of servomotor is not widely used in

industrial motion control, but they form the basis of the simple and cheap

servos used for radio-controlled models.

Radio Control (RC) hobby servos are small actuators designed for

remotely operating model vehicles such as cars, airplanes, and boats.

Nowadays, RC servos are become more popular in robotics. This is because its’

ability to rotate and maintain and certain location, position or angle according to

control pulses from a single wire. Inside a typical RC servo contains a small

motor and gearbox to do the work, a potentiometer to measure the position of

the output gear, and an electronic circuit that controls the motor to make the

output gear move to the desired position. Because all of these components are

packaged into a compact, low-cost unit, RC servos are great actuators for

robots.

More sophisticated servomotors measure both the position and also the

speed of the output shaft. They may also control the speed of their motor, rather

than always running at full speed. Both of these enhancements, usually in


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combination with a PID control algorithm, allow the servomotor to be brought

to its commanded position more quickly and more precisely, with less

overshooting.

Over view

A Servo is a small device that incorporates a three wire DC motor, a gear

train, a potentiometer, an integrated circuit, and an output shaft bearing. Of the

three wires that stick out from the motor casing, one is for power, one is for

ground, and one is a control input line. The shaft of the servo can be positioned

to specific angular positions by sending a coded signal. As long as the codedsignal exists on the input line, the servo will maintain the angular position of the

shaft. If the coded signal changes, then the angular position of the shaft

changes.

Servos come in different sizes but use similar control schemes and are

extremely useful in robotics. The motors are small and are extremely powerful

for their size. It also draws power proportional to the mechanical load. A lightly

loaded servo, therefore, doesnt consume much energy.

A very common use of servos is in Radio Controlled models like cars,

airplanes, robots, and puppets. They are also used in powerful heavy-duty sail

boats. Servos are rated for Speed and Torque. Normally there are two servos of

the same kind, one geared towards speed (sacrificing torque), and the other

towards torque (sacrificing speed)

Servos are constructed from three basic pieces; a motor, a potentiometer

(variable resister) that is connected to the output shaft, and a control board. The

potentiometer allows the control circuitry to monitor the current angle of the


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servo motor. The motor, through a series of gears, turns the output shaft and the

potentiometer simultaneously. The potentiometer is fed into the servo control

circuit and when the control circuit detects that the position is correct, it stops

the motor. If the control circuit detects that the angle is not correct, it will turn

the motor the correct direction until the angle is correct. Normally a servo is

used to control an angular motion of between 0 and 180 degrees. It is not

mechanically capable (unless modified) of turning any farther due to the

mechanical stop build on to the main output gear.

The amount of power applied to the motor is proportional to the distance

it needs to travel. So, if the shaft needs to turn a large distance, the motor will

run at full speed. If it needs to turn only a small amount, the motor will run at a

slower speed. This is called proportional control.

SERVOMOTOR VS STEPPERMOTOR

Servomotors are generally used as a high performance alternative to the

stepper motor. Stepper motors have some inherent ability to control position, as

they have inbuilt output steps. This often allows them to be used as an open-

loop position control, without any feedback encoder, as their drive signal

specifies the number of steps of movement to rotate. This lack of feedback

though limits their performance, as the stepper motor can only drive a load that

is well within its capacity, otherwise missed steps under load may lead to

positioning errors.

The encoder and controller of a servomotor are an additional cost, but

they optimize the performance of the overall system (for all of speed, power

and accuracy) relative to the capacity of the basic motor. With larger systems,


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where a powerful motor represents an increasing proportion of the system cost,

servomotors have the advantage.

Many applications, such as laser cutting machines, may be offered in two

ranges, the low-priced range using stepper motors and the high-performance

range using servomotors.

vcc

Gnd

Figure 3.9: servo motor

Working

servomechanism is used for controlling the servomotor.The servos are

controlled by sending them a pulse of variable width. The control wire is used

to send this pulse. The parameters for this pulse are that it has a minimum pulse,

a maximum pulse, and a repetition rate. Given the rotation constraints of the

servo, neutral is defined to be the position where the servo has exactly the same

amount of potential rotation in the clockwise direction as it does in the counter

clockwise direction. It is important to note that different servos will have

different constraints on their rotation but they all have a neutral position, and

that position is always around 1.5 milliseconds (ms). The angle is determined

by the duration of a pulse that is applied to the control wire. This is called Pulse

width Modulation. The servo expects to see a pulse every 20 ms. The length of

Control signal


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the pulse will determine how far the motor turns. For example, a 1.5 ms pulse

will make the motor turn to the 90 degree position (neutral position).

When these servos are commanded to move they will move to the

position and hold that position. If an external force pushes against the servo

while the servo is holding a position, the servo will resist from moving out of

that position. The maximum amount of force the servo can exert is the torque

rating of the servo. Servos will not hold their position forever though; the

position pulse must be repeated to instruct the servo to stay in position.

When a pulse is sent to a servo that is less than about 0.6 ms the servo does not

rotates to any position and holds its output shaft at zero degree. If the pulse is

wider than 0.6 ms the servo rotates. For example, if pulse width is equal to 1,5

ms servo will rotate 90 degrees and for pulse width is equal or greater than 2

ms, servo will make rotation of 180 degrees. The minimal width and the

maximum width of pulse that will command the servo to turn to a valid position

are functions of each servo. Different brands, and even different servos of the

0.6

1.5

2

Figure 3.10: PWM switching of servo motor


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same brand, will have different maximum and minimums. Generally the

minimum pulse will be about 1 ms wide and the maximum pulse will be 2 ms

wide.This is PWM switching.

Description: This Light Weight Servo (1.5 Kg) can be used for our project

development. This comes with a standard 3 pin power, control cable. Can be

used in Electric aircraft, glider etc.

3.2 TRAIN COLLISION AVOIDANCE

Now a day’s people prefer to travel in Train instead of Bus, according a

lot of changes the way of using our transport systems. More and more trains are

aiding for the transportation systems. At the same time the probable of train to

train collision increasing day by day. Train Collisions are of different types

depending upon the circumstance. There so many technology updates in this

connection to avoid collisions and save the people. In the present railway

signalling system, train location is detected by the track circuit, and according

to train location, train control signals are indicated to prevent collisions between

trains. But these present technologies cannot avoid collision completely.

This paper introduces a new approach addressing the problem of

colliding trains. The system uses the latest communication and sensor

technologies. If the system detects an imminent collision, the power supply of

the train will cutoff and the train will be stop within next few seconds. And the

collision can be avoided. The collision avoidance system mainly consist three

components. The first main component is a short range communication system.The short range communication system used here is Zigbee. The second

important component is its vibration identifying system. Accurate sensing is

very important for collision avoidance system. The vibration of each train is

essential information for the situation analysis. Here the vibration sensor is used


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to identify the train vibration. The PIC microcontroller 16f877a and 16f73 is

used as hardware platform to monitor and control the train operation like,

communication between train and station.

When we are standing at the railway crossing, we can easily know the

arrival of the train only by sensing the intensity of the vibrations created on the

metal tracks on which train runs. Thus, the intensity of the vibrations created

during passage of a train at the railroads or railways tracks can be identified by

vibration sensor. Vibration Sensor that works according to the high and low

intensity of the vibrations created on railway tracks whenever trains run on it.

The vibration sensors are attached on the railway track. It is an intelligent

system that can sense the increasing and decreasing amount of vibrations being

created on railway tracks and it converts mechanical vibration into electrical

signal. Then it sends the relevant signal to the attached PIC microcontroller

through the analog pin and work accordingly without any other intervention. If

the train comes in both the direction more than one sensor shows higher value.

So the microcontroller identifies the trains come in opposite direction. Output

of the microcontroller goes to the other PIC microcontroller 16f73 in the train

side through the transmitter and receiver section of the zigbee. The engines of

trains are equipped with microcontroller containing all the data and information

about all the trains. Then the power supply of the train will cutoff and the train

will be stopped within few seconds.

Based on immediate response against the vibrations created, the proposed

mechanism will be cost-effective, flawless and quite secure for the general

public. It avoiding frequently occurring collisions. If this technology is

implemented in all rail road railings, the overall collision rate can be reduced

significantly and travel will become safe for everyone.


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3.3 TRAIN DERAILMENT

Train derailment is mainly occurred due to the presence of crack in the

railway track. The major problems that railroads have faced since the earliest

days are the prevention of service failures in track. As is the case with all modes

of high-speed travel, Rail is manufactured in different weights; there are

different rail conditions wear, corrosion etc. present there are a significant

number of potential defects possible and the task has to be performed with some

speed to reliably inspect the thousands of miles of track stretching across the

land failures of an essential component can have serious consequences. The

main problem about a railway analysis is detection of cracks in the structure. If

these deficiencies are not controlled at early stages they might cause huge

economical problems affecting the rail network unexpected requisition of spare

parts, handling of incident and/or accidents.

Figure 3.11: General schematic of a track

RAIL

FISH PLATE BOLT

SPIKE

TIE

EXPANSION

SPACE

NUT

TIE

PLATE


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If there is any crack in the railway track, the vibration of train will not get

continuously by the vibration sensor. This means that the crack is present. So

we have to stop the train before passing the crack. The vibration sensor values

are given to the analog channels of microcontroller. The microcontroller

PIC16F877A is used at the base station .The vibration sensor and ZigBee is

interfaced with the microcontroller. The ZigBee transceiver transfers the

information to the transceiver present at the train side.

The train side a brake control system is present. When the false signal

(presence of crack) reaches the train will automatically stops by releasing the

brake of train. Thus the train can be stopped before the crack. There by we can

avoid the derailment of trains in bends and curves.

3.4 AUTOMATIC GATE CONTROL

One of the main objectives of this project is to control the unmanned rail

gate automatically using embedded platform to reduce maintenanceexpenditure, human mistakes, and accidents. An Embedded system is a

combination of computer hardware and software, and perhaps additional

mechanical or other parts, designed to perform a specific function.

The largest public sector in India is the Railways. The network of Indian

Railways covering the length and breadth of our country is divided into nine

Railway zones for operational convenience. The railway tracks crises-cross thestate Highways and of course village road along their own length. The points or

places where the Railway track crosses the road are called level crossings.

Level crossings cannot be used simultaneously both by road traffic and trains,

as this result in accidents leading to loss of precious lives.


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Today often we see news papers very often about the railway accidents

happening at un- attended railway gates. This project is developed in order to

help the INDIAN RAILWAYS in making its present working system a better

one, by eliminating some of the loopholes existing in it. The program for this

project is embedded in this Micro controller Integrated Chip and interfaced to

all the peripherals.

Early level crossings had a flagman in a nearby booth that would, on the

approach of a train, wave a red flag or lantern to stop all traffic and clear the

tracks. Manual or electrical closable gates that barricaded the roadway were

later introduced. The gates were intended to be a complete barrier against

intrusion of any road traffic onto the railway. In the early days of the railways

much road traffic was horse drawn or included livestock. It was thus necessary

to provide a real barrier. Thus, crossing gates, when closed to road traffic,

crossed the entire width of the road. When opened to allow road users to cross

the line, the gates were swung across the width of the railway, preventing any

pedestrians or animals getting onto the line. With the appearance of motorvehicles, this barrier became less effective and the need for a barrier to

livestock diminished dramatically. Many countries therefore substituted the

gated crossings with weaker but more highly visible barriers and relied upon

road users following the associated warning signals to stop. In many countries,

level crossings on less important roads and railway lines are often "open" or

"uncontrolled", sometimes with warning lights or bells to warn of approaching

trains. Ungated crossings represent a safety concern; many accidents have

occurred due to failure to notice or obey the warning. Level crossings in India,

China, Thailand, and Malaysia are still largely manually-operated, where the

barriers are lowered using a manual switch when trains approach.


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Existing System:-

1. Manual/Physical gate closing & opening.

2. Manual switch based gate closing & opening.

Limitations of exiting system:-

1. Chances of human error.

2. Time consuming.

3. A lot of human resource is required.

An automatic railway gate at a level crossing replacing the gates operated

by the gatekeeper. It 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. By the presently existing system once

the train leaves the station, the stationmaster informs the gatekeeper about the

arrival of the train through the telephone. Once the gatekeeper receives the

information, he closes the gate depending on the timing at which the train

arrives. Hence, if the train is late due to certain reasons, then gate remain closed

for a long time causing traffic near the gates. By employing the automatic

railway gate control 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.

This type of gates can be employed in an unmanned level crossing where the

chances of accidents are higher and reliable operation is required. Since, the

operation is automatic; error due to manual operation is prevented. Automaticrailway gate control is highly economical microcontroller based arrangement,

designed for use in almost all the unmanned level crossings in the country”. It

intends to attain the following objectives: 1.To design a system that will

enhance the existing railway gate control system. 2. To incorporate C-


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Programming in the design of the “Automatic Railway Gate Control and Track

Switching”. 3. To show the application of automation in the miniature prototype

of the “Automatic Railway Gate Control and Track Switching”.

Using simple electronic components we have tried to automate the

control of railway gates. For that it uses PIC micro controller PIC16F877A and

PIC16F73, vibration sensor, Zig-Bee module, servo motor etc. As a train

approaches the railway crossing the vibration sensor placed near the crossing

will sense the vibrations and give the measured values to the base station which

is controlled by the micro controller. The Zig-Bee Transceiver connected to the

micro controller (PIC16F877A) will send a signal to the Zig-Bee Transceiver

which is placed over the train. The train is also controlled by the micro

controller PIC16F73.Then the train side PIC will send a signal to the gate which

is controlled by the servo motor.


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FLOW CHART FOR RAILWAY GATE CONTROL

Figure 3.12: flow chart for automatic railway gate control

START

CHECH ANY

DATA PRESENT

IF DATARXEDFROM

TRAIN


51/76

FLOW CHART FOR STOPPING THE TRAIN

Figure 3.13: flow chart for brake control of train

SCAN FOR THE STATUS OF RC6

RB0=0

Train

START

START

IS

RC6=1

SET RB0=0 TO STOP TRAIN

SET RB0=1 TRAIN USING

MANUAL OVERRIDE


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3.5 CIRCUIT DIAGRAM

3.5.1 BASE STATION

Figure 3.14: circuit diagram of base station side


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3.5.2 TRAIN SIDE

Figure 3.15: circuit diagram of train side


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3.6 CIRCUIT DIAGRAM DESCRIPTION

3.6.1 REGULATED POWER SUPPLY:

A variable regulated power supply, also called a variable bench power

supply, is one which you can continuously adjust the output voltage to your

requirements. Varying the output of the power supply is recommended way to

test a project after having double checked parts placement against circuit

drawings and the parts placement.

This type of regulation is ideal for having a simple variable bench power

supply. Actually this is quite important because one of the first projects a

hobbyist should undertake is the construction of a variable regulated power

supply. While a dedicated supply is quite handy e.g. 5V or 12V, it’s much

handier to have a variable supply on hand, especially for testing.

Most digital logic circuits and processors need a 5 volt power supply. To

use these parts we need to build a regulated 5 volt source. Usually you start

with an unregulated power to make a 5 volt power supply; we use a LM7805

voltage regulator IC (Integrated Circuit).

Figure 3.16: LM 7805 block diagram

705

5

+

+

2 1


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The LM7805 is simple to use. We can simply connect the positive lead to

the unregulated DC power supply (anything from 9VDC to 24VDC) to the

Input pin, connect the negative lead to the Common pin and then when you turn

on the power, you get a 5 volt supply from the Output pin.

Circuit features:

• Brief description of operation: Gives out well regulated +5V output,

output current capability of 100mA.

•

Circuit protection: Built-in overheating protection shuts down output

when regulator IC gets too hot.

•

Circuit complexity: Very simple and easy to build.

• Circuit performance: Very stable +5V output voltage, reliable operation

• Availability of components: Easy to get, uses only very common basic

components.

Figure 3.17: Pin representation of LM 7805


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•

Design testing: Based on datasheet example circuit, I have used this

circuit successfully as part of many electronic projects.

• Applications: Part of electronics devices, small laboratory power supply

3.6.2 TIP122

The TIP122 is silicon Epitaxial-Base NPN power transistors in

monolithic Darlington configuration mounted in Jedec TO-220 plastic package.

They are intented for use in power linear and switching applications.

Here 1 represents base 2 represents collector and 3 represents emitter.

The devices are manufactured in planar technology with “base island” layout

and monolithic Darlington configuration. The resulting transistors show

exceptional high gain performance coupled with very low saturation voltage.

Figure 3.18: transistor TIP 122


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Transistor polarity NPN

Continues collector current Ic max 5A

Power dissipation 2w

DC collector current 5v

DC current gain hFE 1000

No of pins 3

Full power rating temperature 25°C

Hfe min 1000

3.6.3 LITHIUM ION BATTERY

Lithium-ion battery (sometimes Li-ion battery or LIB) is a member of a

family of rechargeable battery types in which lithium ions move from the

negative electrode to the positive electrode during discharge, and back whencharging. Li-ion batteries use an intercalated lithium compound as the electrode

material, compared to the metallic lithium used in the non-rechargeable lithium

battery.

The three primary functional components of a lithium-ion battery are the

negative electrode, positive electrode, and the electrolyte. The negative

electrode of a conventional lithium-ion cell is made from carbon. The positiveelectrode is a metal oxide, and the electrolyte is a lithium salt in an organic

solvent. The electrochemical roles of the electrodes change between anode and

cathode, depending on the direction of current flow through the cell. The most

commercially popular negative electrode material is graphite. The positive

Table 3.2: Features of TIP 122 transistor


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electrode is generally one of three materials: a layered oxide (such as lithium

cobalt oxide), a polyanion (such as lithium iron phosphate), or a spinel (such as

lithium manganese oxide). The electrolyte is typically a mixture of organic

carbonates such as ethylene carbonate or diethyl carbonate containing

complexes of lithium ions. These non-aqueous electrolytes generally use non-

coordinating anion salts such as lithium hexafluorophosphate (LiPF6), lithium

hexafluoroarsenate monohydrate (LiAsF6), lithium perchlorate (LiClO4),

lithium tetrafluoroborate (LiBF4), and lithium triflate (LiCF3SO3). Depending

on materials choices, the voltage, capacity, life, and safety of a lithium-ion

battery can change dramatically. Recently, novel architectures using

nanotechnology have been employed to improve performance. Pure lithium is

very reactive. It reacts vigorously with water to form lithium hydroxide and

hydrogen gas. Thus, a non-aqueous electrolyte is typically used, and a sealed

container rigidly excludes water from the battery pack. Lithium ion batteries are

more expensive than NiCd batteries but operate over a wider temperature range

with higher energy densities, while being smaller and lighter. They are fragile

and so need a protective circuit to limit peak voltages.

Li-Ion Battery 7.4V 700mAh (1C)

Very light weight and small size compared to Ni-Cd, Ni-MH and Lead

acid batteries. Very long life without losing charging capacity. Weights just 80

grams. This battery includes an inbuilt charger and protection circuit which

allows you to use this battery without worrying about over discharge, over

charge or short circuit. For charging just connect to any 9V & max 1A power

source. This battery can be use inline just like mobile phone battery, when

connected to charger it can still use as circuit or robot and charge battery

simultaneously.


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Features

• Very Small in size and weight compared to Ni-Cd, Ni-MH and Lead

Acid Batteries

• Discharge Current upto 1A

• Full Charge in 120 minutes depending on power source

• Long life with full capacity for upto 1000 charge cycles

• Inbuilt charge and discharge protection circuit

• Inbuilt charge controller, no dedicated charger required, use any 9V 1A

supply to charge

•

Can be used in inline application where battery is for backup, use while

you are charging

3.6.4 CRYSTAL OSCILLATOR

The 16 MHz Crystal Oscillator module is designed to handle off-chip

crystals that have a frequency of 4.16 MHz. The crystal oscillator’s output is

fed to the System PLL as the input reference. The oscillator design generates

low frequency and phase jitter, which is recommended for USB operation.

Crystal Equivalent Circuit

Figure 3.19: Crystal electrical equivalent schematic


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The crystal model is based on the following components:

L: Motional Inductor

C: Motional Capacitor

R: Equivalent Series Resistor

Cc: Shunt Capacitor

Operational oscillation frequency is a function of the components in

Freq = 1/[2*pi*sqrt(L*C)]

The conditions for oscillation are as follows:

• Amplifier Gain ≥ 1

• Total phase shift across crystal = 360 degrees

The following factors influence crystal oscillation:

1. As Cc increases, Gain decreases.

2. As R increases, Gain decreases.

3. The C1 and C2 load capacitors affect the gain and phase margin

Enabling the On-Chip 16 MHz Oscillator

To use the on-chip 16 MHz oscillator with a crystal, you must use a high

quality crystal with an ESR below 20 ohms. To enable the on-chip 16 MHz

oscillator, the Clock Source Control Register (CSCR) must have the following

settings:

• CLKO_SEL . Set to any value other than 011 (CLK16M).

•

OSC_EN . To enable the on-chip 16 MHz oscillator, set to 1.

•

Set System_SEL . To select the 16 MHz oscillator as the clock source of

the System PLL, set to 1.


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Caution

When you enable the on-chip 16 MHz oscillator, make sure CLKO_SEL is not

set to output CLK16M. Experiments have shown that this setting can load down

the on-chip oscillator during crystal start up. After the 16 MHz oscillator starts

to oscillate, however, it is all right to output CLK16M. If you are not using the

CLKO signal, it is advisable to disable the CLKO pin by setting CLKO_SEL to

110 or 111.

Applications

•

Automotive

• Cable Modems

• Cell Phones

• Computer Peripherals

•

Copiers

• Infotainment

• PCs

• Printers

Figure 3.20: Crystal electrical equivalent schematic


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Applications Information

• Crystal Selection

The DS1080L requires a parallel resonating crystal operating in the

fundamental mode, with an ESR of less than 90Ω. The crystal should be placed

very close to the device to minimize excessive loading due to parasitic

capacitances.

• Oscillator Input

When driving the DS1080L using an external oscillator clock, consider the

input (X1) to be high impedance.

• Crystal Capacitor Selection

The load capacitors CL1 and CL2 are selected based on the crystal

specifications (from the data sheet of the crystal used). The crystal parallel load

capacitance is calculated as follows:

CL=[(CL1*CL2)/ (CL1+CL2)]CIN

For the DS1080L use CL1 = CL2 = CLX. In this case, the equation then

reduces to:

CL= (CLX/2) +CIN

Where CL1 = CL2 = CLX.

Equation 2 is used to calculate the values of CL1 and CL2 based on values on

CL and CIN noted in the data sheet electrical specifications.

•

Power-Supply Decoupling

To achieve best results, it is highly recommended that a decoupling capacitor is

used on the IC power-supply pins. Typical values of decoupling capacitors are

0.001µF and 0.1µF. Use a high-quality, ceramic, surface- mount capacitor, and


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mount it as close as possible to the VCC and GND pins of the IC to minimize

lead inductance.

• Layout Considerations

As noted earlier, the crystal should be placed very close to the device to

minimize excessive loading due to parasitic capacitances. Care should also be

taken to minimize loading on pins that could be floated as a programming

option (SMSEL and CMSEL). Coupling on inputs due to clocks should be

minimized.

3.6.5 RELAY SWITCHA relay is an electrically operated switch. Many relays use an

electromagnet to operate a switching mechanism mechanically, but other

operating principles are also used. Relays are used where it is necessary to

control a circuit by a low-power signal (with complete electrical isolation

between control and controlled circuits), or where several circuits must be

controlled by one signal. The first relays were used in long distance telegraph

circuits, repeating the signal coming in from one circuit and re-transmitting it to

another. Relays were used extensively in telephone exchanges and early

computers to perform logical operations

A type of relay that can handle the high power required to directly

control an electric motor or other loads is called a contractor. Solid-state relays

control power circuits with no moving parts, instead using a semiconductor

device to perform switching. Relays with calibrated operating characteristics

and sometimes multiple operating coils are used to protect electrical circuits

from overload or faults; in modern electric power systems these functions are

performed by digital instruments still called "protective relays".


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3.7 OVER VIEW OF T

The sensors sens

responds and gives co

algorithm. The time par

modified using Micro-c

would help to reduce the

3.8 SOFTWARE SPEC

3.8.1 MPLAB IDE

MPLAB Integrate

toolset for the develop

PIC and dsPIC microco

MS Windows, is easy t

Figure 3.21:

HE PROPOSED SYSTEM

the input and sends to the microcontr

mand to the particular component w

ameters are crucial which can be easil

ntrollers. Thus, this device would wor

train collisions.

IFICATION

d Development Environment (IDE) is a

ent of embedded applications employi

trollers. MPLAB IDE runs as a 32-bit

use and includes a host of free softwa

ver view of the proposed system

oller, where it

ith predefined

changed and

in coherence

ree, integrated

g Microchip’s

application on

e components


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for fast application development and supercharged debugging. MPLAB IDE

also serves as a single, unified graphical user interface for additional Microchip

and third party software and hardware development tools. Moving between

tools is a snap, and upgrading from the free software simulator to hardware

debug and programming tools is done in a flash because MPLAB IDE has the

same user interface for all tools. A development system for embedded

controllers is a system of programs running on a desktop PC to help write, edit,

debug and program code- the intelligence of embedded systems applications in

to a microcontroller. MPLAB IDE runs on a PC and contains all the

components needed to design and deploy embedded systems applications.

MPLAB IDE Programmer’s Editor Helps write correct code with the language

tools of choice. The editor is aware of the assembler and compiler programming

constructs and automatically “color-keys” the source code to help ensure it is

syntactically correct. The Project Manager enables you to organize the various

files used in your application source files, processor description header files and

library files. Language tools run into errors when building the application, the

offending line is shown and can be “double-clicked” to go to the corresponding

source for immediate editing. After editing, press the “build” button to try

again. Often this write-compile-fix loop is done many times for complex code,

as the subsections are written and tested.

Once the code builds with no errors, it needs to be tested. MPLAB IDE

has components call

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