Design and Development of a Mechatronic System for

Discovery

ANALYSIS

The International Daily journal

ISSN 2278 – 5469 EISSN 2278 – 5450 © 2015 Discovery Publication. All Rights Reserved

Design and Development of a Mechatronic System for the Measurement of Railway Tracks Publication History Received: 23 August 2015 Accepted: 20 September 2015 Published: 15 October 2015

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Citation Ketan Tamboli, Saurin Sheth, Viraj Shah, Chintan Gandhi, Neel Amin, Vivek Modi. Design and Development of a Mechatronic System for the Measurement of Railway Tracks. Discovery, 2015, 43(200), 174-180

Design and Development of a Mechatronic System for the Measurement of Railway Tracks Ketan Tamboli(a*), Saurin Sheth(a*)

Viraj Shah

Chintan Gandhi

Neel Amin

Vivek Modi

(a*)

Practising Engg Iolite Cube infra material Ltd., Vadodara

Practising Engg Cosmos Pvt Ltd.,

Practising Engg. Infosys

Vadodara

Pune

PG Student University Of Windsor Canada

An innovative approach for measuring the railway parameters (inspection of parallelism, levelling, etc.) based on principles of sensing and data acquisition is presented. It can overcome the challenges in existing system faced by Indian Railway. The existing system “gauge cum level” commonly used to measure levelling and parallelism of railway tracks consists of sensitive spring mechanism and spirit level to measure gauge and levelling respectively. It is a manually operated system and is of contact type mechanism. The range of the instrument is +20 to -10mm with minimum accuracy of 1mm in gauge and Super elevation range of -30 mm to + 200 mm Cross level precision of + 1.0 mm. In the proposed system, it is manned to mount and orient sensors on a motor driven unit which keeps track of the rails by sensing. In case of misalignment of rails, sensor gives signal to microcontroller which gives knowledge of degree of misalignment and displays on display unit. Microcontroller also does job of synchronization between sensors and motor (switching timing of sensor and motor of mechanical system).Experimentation and testing has been carried out to prove its practicality. The work showed is original and is tested in real environment. ABSTRACT-

Keywords- Parallelism, Innovative, Synchronization, Data acquisition.

I.

INTRODUCTION Day by day technology is getting advanced in railway systems and the day is not far when every system of railways will be automated. With increasing risks involved in safety of public and properties, attention must also be given to proper alignment, parallelism and levelling of railway

tracks. In 1920 Railway board issued a schedule of minimum, maximum and recommended dimensions to be observed on all 1676 mm gauge railways in India. The schedule of dimensions of 1922 contained two distinct sections, namely, a schedule of "Maximum and Minimum Dimensions" which was considered to enable the proposed larger vehicles to run with about the same degree of safety as that which was previously obtained on the older Railways. Mechanized maintenance of track on Indian Railways was introduced. During early sixties, Modern track cannot be maintained and laid manually and thus use of machines has become a basic necessity. Track Machines on Indian Railways have been categorized as Small Track Machines & Large Track Machines. Due to growing traffic and introduction of heavier track structure, faster and more efficient methods of maintenance are needed to be evolved. In the change socio-economic scenario, role of small track machines has increased for quality maintenance of track. Different types of small machines have been developed for various activities on track. These small track machines are to be used for day-to-day maintenance, laying and construction of track.

II.

STUDY OF EXISTING SYSTEM

A brief explanation of existing system is given in following sub sections. Working and technical details: The gauge- cum- level (Refer Fig1 and Fig2) is an instrument which is used to measure the gauge as well as the cross level of Railway track simultaneously. Gauge-cum-level comprises two main items i.e., the ‘gauge’ and a spirit level conforming to the RDSO (Research Designs and Standards Organisation) specification. The gauge is fitted with two gauge tips of which one is fixed and other is of sliding type. The hardness of rail seating and gauge tips lies in the range of 40HRc to

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G.H. Patel college of Engg & Tech, V V Nagar , India

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Asso Prof Department of Mechatronics

PROPOSED SYSTEM

IV.

ELECTRONICS DESIGN

Detailed description of main components of electronic system is discussed in subsections. A. Micro-controller- Arduino Uno Arduino is an open-source single-board microcontroller, descendant of the open-source Wiring platform, designed to make the process of using electronics in multidisciplinary projects more accessible. The hardware consists of a simple open hardware design for the Arduino board with an Atmel AVR processor and on-board input/output support. The software consists of a standard programming language compiler and the boot loader that runs on the board. Arduino hardware is programmed using a Wiringbased language (syntax and libraries), similar to C++ with little simplifications and modifications, and a Processing-based integrated development environment. Current versions can be purchased pre-assembled; hardware design information is available for those who would like to assemble an Arduino by hand. Additionally, variations of the Italian-made Arduino—with varying levels of compatibility—have been released by third parties; some of them are programmed using the Arduino software.( arduino.cc/en/Main/arduinoBoardUno) Arduino code: Code is developed into two parts: 1. Code for measurement 2. Code for display Code for Measurement: This code includes setting up the ARDUINO pins for necessary inputs and outputs, reading analog values from inductive sensor and converting into digital values, calibration of the sensor values in terms of distance, calculation for the error, storing of error values in EEPROM of the microcontroller for displaying it on LCD in latter stage. Code for display: This code includes reading values from EEPROM, necessary commands for interfacing LCD with Arduino, displaying values on LCD, displaying type of error (slack/tight).( E. Balagurusamy,2008) Code includes following functions: pinMode(pin, state) To set pin and its state digitalWrite(pin,state) To make pin high or low digitalRead(pin state) To read pin high or low delay(time) To have delay (in terms of 10-3) analogRead(pin) To read values from analog pin

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III.

A novel system comprising of electronic components such as micro-controller, PMDC motor, inductive sensor, display unit, etc. is presented with block diagram and working in following sections. A. Block diagram In order to make the measurement system semi-automated a closed loop control system (as shown in Fig.4) is proposed which synchronizes the alternate switching of sensor and motor to measure the gauge of tracks.( M. M. Agarwal,1984, V. B. Sood) B. Mechanical design According to the requirements of the system and external forces acting on the system, shaft diameter and chassis is designed considering normal forces, bending forces and pulley design laws. On performing calculations and constructing

different bending moment diagrams, diameter of shaft is found to be 30mm and chassis dimensions are considered based on railway track standards and weight criteria. (Refer Fig 10)

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45HRc.or measurement of cross level, the housing frame is provided with three ramps i.e., smaller ramp, horizontal platform and longer ramp. (Indian Railway Tender, 2001).Cross level from 1 to 30 mm is measured by smaller whereas cross level from 1 mm to 200 mm is measured by the longer ramp. Graduations shall be neatly etched/ embossed on the scales provided on the ramps. The sliding assembly is housed inside the main frame and is comprising of one sliding gauge tip (round), a connecting rod with compression spring and two fixed blocks. block at the other end through two fixed blocks which the connecting rod is fitted with the sliding gauge tip (round) at one end and a movable gauge scale are screwed to the main frame. The sliding tip is so designed, that it can be reused after reversal of the same by 180° and is capable to measure gauge correctly in both positions. In between the two fixed blocks compression spring is provided. The movable gauge scale block carry the ‘gauge – scale’ at the top. This scale is clearly visible from outside through the glass of the eye piece. The glass is provided with an indicator at the centre which is the reference mark to correctly show the correct reading of the gauge on the sliding scale. The gauge- cum- level conform the following technical requirements: Nominal Gauge (B G) : 1676m Overall length : 1840+5mm Height of Rectangular tubing : 50.8mm Width of Rectangular tubing : 25.4mm Thickness of Rectangular tubing : 2 mm Length of horizontal platform : 200mm Measuring range for gauge : +20to-10mm Accuracy for gauge : 1.0mm Super elevation range : -30 to + 200mm Cross level precision : 1mm

D. Liquid Crystal Display

Pin no 1 2

3

Function Ground (0V) Supply voltage (4.7V-5.3V) Contrast adjustment; through a variable resistor

Name Ground Vcc

Vee

Command and Data. The command register stores the command instructions given to the LCD. A command is an instruction given to LCD to do a predefined task like initializing it, clearing its screen, setting the cursor position, controlling display etc. The data register stores the data to be displayed on the LCD. The data is the ASCII value of the character to be displayed on the LCD (Pin number description is given in table 3). Table 2. Pin Number of LCD 4

5

6

7 8 9

Selects commands resistor when low; and data resistor when high Low to write to the resistor; high to read from resistor Sends a data to data pin when high to low pulse is given 8-bit data pins Backlight Vcc (5V) Backlight ground (0V)

Resistor select

Read/Write

Enable

DB0-DB7 Led+ Led-

E. Other components Battery: 12V, 1A, lead acid batteries. Relay: Relay is used as an electro-magnetic switch (5V DC) Operational Amplifier: OPAMP with negative feedback is used as a filtering element for scaling 0-14V to 0-5V.

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Table 1. Specifications of Proximity Inductive Sensors Operating voltage 12VDC Type Analog Sensing distance 15mm Probe diameter 20mm Output voltage 0-10V Max. frequency 500Hz

A 16x2 LCD means it can display 16 characters per line and there are 2 such lines. In this LCD each character is displayed in 5x7 pixel matrix. This LCD has two registers, namely,

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If(condition) Decision function Serial.print(“statement”) To print statement on serial monitor EEPROM.write(address,value) To write on EEPROM EEPROM.read(address) To read from EEPROM For(initialization, condition, inc/dec) Control loop lcd.begin(col,row) To specify type of lcd lcd.setcursor(m,n) To specify location on lcd lcd.print(“statement”) To print statement on lcd screen lcd.clear Clear the display on lcd B. PMDC motor In a PMDC motor, an armature rotates inside a permanent magnetic field. Basic working principle of dc motor is based on the fact that whenever a current carrying conductor is placed inside a magnetic field, there will be mechanical force experienced by that conductor. This motor is chosen as it has low speed of 30 rpm approximately and high torque as per system requirement. C. Inductive sensor An inductive proximity sensor consists of an oscillator, a ferrite core with coil, a detector circuit, output circuit housing, and a cable or connector. The oscillator generates a sine wave of a fixed frequency. This signal is used to drive the coil. The coil in conjunction with ferrite core induces electromagnetic field. When the field lines are interrupted by a metal object, the oscillator voltage is reduced, proportional to the size and distance of the object from the coil. Inductive proximity sensor is chosen because it is suitable for concentrated area, has high switching frequency and has performance in detecting distance of a iron metal(rail tracks). According to the application required , two inductive sensors will sense the two rails of the track by mounting it on mechanical unit such that it is perpendicular to the side face of the rail and send the analog reading to the microcontroller passing through filtering and deamplification circuit (Refer Table 1).

The selected inductive analog sensor gives 0 to 14 volts (analog) hence in order to interface with Arduino Uno which accepts only 0 to 5 volts (analog) at analog input pin, de-amplification circuit is needed. Following circuits has been experimented and simulated : 1. 0.36 gain inverse feed-back op-amp circuit. 2. Potential divider circuit. 3. Potential divider circuit in series with unity gain inverse feedback opamp circuit. A. Experiment 1: 0.36 gain inverse feedback op-amp circuit Components: LM-339 IC, 240- ohm resistor 1K-ohm resistor, four 10 K-ohm pot., two 20 K-ohm pot., PCB, 12V DC, 1micro-F capacitor, 20K-ohm pot., battery, connecting wires(Refer Fig 5 and 9). Observation Interfacing this circuit with sensor it was observed that by moving sensor from its maximum to its minimum position the output voltage was from 2.20 to 5 V (analog). Conclusion From the result it is concluded that there was constant output 2.20 volts for minimum distance and there was no output below 2.2 volts( A. K. Sawhney,2011). B. Experiment 2: Voltage Divider Circuit Components: PCB, 20K- ohm pot., 10K-ohm pot., 0.1 micro-F capacitors (2), connecting wires, 12V battery(refer fig 3 and 6). Observation 1. Interfacing this circuit with sensor it was observed that by moving sensor from its maximum to its minimum position the output voltage was from 0 to 5 V (analog). 2. It fulfils the aim of mapping 0 to 14 V to 0 to 5 V but interfacing with Arduino the analog value from ADC of Arduino gives wide range of values for a fixed distance (eg: if the distance is 0 than analog value varies from 410 to 530). Conclusion 1. Mapping of 0 to 14 volts to 0 to 5 volts is accomplished. 2. For fixed distance of sensors it gives wide range of ADC values, hence difficult to calibrate. C. Experiment 3: Potential divider circuit in series with unity gain inverse feedback opamp circuit Components: PCB, 20K- ohm pot., 10K-ohm pot., two 2.2K-ohm resistors, LM339 IC, 1K-ohm resistor, 0.1 micro-F capacitors (2), connecting wires, 12V battery Observation

1. Interfacing this circuit with sensor it was observed that by moving sensor from its maximum to its minimum position the output voltage was from 0 to 5 V (analog). 2. It fulfils the aim of mapping 0 to 14 V to 0 to 5 V and for fixed distance of sensors narrow range of ADC value is obtained. Conclusion 1. Mapping of 0 to 14 volts to 0 to 5 volts is accomplished 2. For fixed distance of sensors it gives narrow range of ADC values. Hence comparatively easy to calibrate (Refer Fig 7). After these experiments, and achieving conclusion, potential divider circuit in series with unity gain inverse feedback opamp circuit is implemented and sensors are calibrated (shown in table 3 and table 4).

Table 3. Calibration Table of Sensor 1 Sr no

Distance

Mapped ADC values Voltage (05V) Sensor 1 (15 mm), Voltage of battery (13.39 V) 1 0 5 500-504 2 2 5 499 3 4 4.8 487-495 4 6 3.1 309-350 5 8 0.5 443-60 6 10 0.4 39-42 7 12 0.3 36-37 8 15 0.1 38

Table 4. Calibration Table of Sensor 2 Sensor 2 (8mm), voltage of battery (13.39 V) 1 0 5.1 526-528 2 2 5 524-525 3 4 4.9 514-515 4 6 2.2 249-245 5 8 0 0

VI.

WORKING OF PROPOSED SYSTEM

In the proposed system, mounted and properly oriented sensors on a motor driven unit keeps track of the rails by sensing. In case of misalignment of rails, sensor gives signal to microcontroller which gives knowledge of degree of misalignment and displays it on display unit.

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EXPERIMENTATION AND SIMULATION

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Microcontroller also does the job of synchronization between sensors and motor (switching timings of sensor and motor).The new proposed system will satisfy measuring parameters as follows: Nominal Gauge (B G): 1673 mm Measuring range for gauge: + 20 mm to -10 mm Accuracy for gauge: 2mm

VII.

PHOTO GALLERY Fig.4. Block Diagram of Proposed SemiAutomated System

Fig.1. guage cum level meter

Fig.5. Inverse Feedback OP-AMP Circuit

Fig.2. Spring mechanism of sliding end

Fig.6. Simulation of Voltage Divider Circuit

Fig.7. Electronic System Setup

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Fig.3. potential divider circuit

Fig.8. Working Model

Fig.9. Simulation of OP-AMP Circuit

Fig.10. Orthographic views of mechanical system

CONCLUSION By studing existing system, designing mechatronic system which includes conceptual modelling,fundamental task of selection of sensors that to of analog type, scaling output of sensor to the input standards of microcontroller and undergoing experimentation, testing and simulation, it is concluded that this system can measure misalignment having accuracy of 2mm.However the capability of these system can be increased by having good quality of sensor, using image processing to make system understand the difference between the crack and misalignment of the track at the point of measurement on the track.This system can be made fully automatic by designing a software for data acquisition and display of the reading during the measurement(online measurement) .This system can take measurements at the regular interval on the track and number of measurement is based on memory of the controller

References [1] Indian Railway Tender “Specification of box type gauge cum level (bg)”, number tm-58, 2001 [2] M. M. Agarwal: “Indian Railway Track: Design, Construction, Maintenance and Modernisation”, Volume 5,Prabha-1984. [3] A. K. Sawhney: “Electrical and Electronic Measurement and Instrumentation”, Volume 19, DhanpatRai&Co. 2011. [4] arduino.cc/en/Main/arduinoBoardUno [5] E. Balagurusamy: “programming with ANSI C”, Volume 4E, The McGrow Hill Companies2008 [6] V. B. Sood: “Notes on realignment of curves for railway tracks”,

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Acknowledgement We are grateful to the Western Indian Railway for granting permission for experimenting and testing the working model on the rails.