NDT:High Resolution Systems

Sri Tanusha KolliMLR Instituions, Hyderabad Sritanusha003@gmail.com

Ravi KatukamCyeint Limited Hyderabad

Hyderabad IndiaRavi.Katukam@cyient.com

Abstract—Technology usage was growing day byday due its automation mainly in the fields ofscience. Sensors are playing their importantrole in these advancements. The basicnecessity to use a sensor might be the sensingthe right element that which is required bythe user. So the idea of the smartness beganto takes a shape. Sensors made the smartnessto accomplish in a much easy way. This paperdiscuss about some of the technologies thatare used by medical field and can also be usedin aerospace field as technologicaladvancements. Paper mainly reviews theequipments that are already in usage in aparticular field but also has high utility inother fields also. The equipment that themedical industry is using can also be used forNDT also.NDT is a major phase that an aircraftneed to undergo. This paper also explainsabout the sensors that are used in dronesmaking them more helpful.

Keywords—sensors, medical, aerospace, NDT, drones.

The world is run ning aroundsmartness and smart cities are also inimplementation. The main reason would bethe preference of luxury by people andeven technology was also supporting it alot. So the application of smart becameapplicable to each and every field.Reducing the man power and risk factors toa huge extent. The major part in the smartconcept runs around sensors and itssupporting devices. Sensors are not justrestricted to the field of automobileindustry, communication, networking etc.fields but also in aerospace industry.There applications can be found in dronesalso which makes them to increases itsusage. This paper mainly describes about

various sensors that can be used in usedin drone for various applications.

This paper mainly discusses aboutsensors the can be used in Non DestructiveTesting (NDT) applications. This is usedto predict defects that will be generallyoccurring in structural components. NDTis one of the crucial testing phase forevery aircraft to undergo. Here the partwill be tested without destroying it i.e.is the testing the component withoutdestroying its serviceability conditions.Thus making an advantage rather thancompared to other testing conditions. Thispaper mainly concentrates on the sensorsthat can be used in NDT techniques thusmaking it easier to apply and predicts theresults more accurately. There is alsodiscussion about the application ofmedical equipment like CT, radiography inNDT of aircraft.

I. .MEDICAL EQUIPMEMTS IN AEROSPACE NDT:The equipments that are used in

diagnostics are far advanced and canpredict more accurate results than that ofactual devices that are used intraditional NDT techniques. So an attemptwas made to replace the traditionaltechniques with medical equipments. Thefollowing are the some of the equipmentsthat can be used as NDT in aerospacefield. Even they can determine the hairsize defects also which is very muchnecessary for an aero structure todetermine.

A. COMPUTED TOMOGRAPHY:

X-ray is photons with high energy. Itcan penetrate through objects. X-raybeams, usually shaped as a horizontalplanar fan or cone, slice through theobject which rotates and moves vertically.Due to the different absorptions caused bydensity variation through the section, theintensities of X-rays pass through theobject will indicate the structuralvariation which is captured and convertedinto measurable signals. Image intensifierconverts x-ray energy into light, which isthen captured by video camera and turnsinto image pixels. Many slices are thencombined by mathematical operations tocreate CT image. So, the CT system allowsthe visualization and digitalization ofinternal structure without breaking theobject.The below figure shows the setup for CTscan.

The figure below shows the outputobtained for an assembly of pipe componentthrough CT scan.

SENSOR USAGE: Sensors measure theamount of radiation absorbed by thedifferent components. By which an crosssectional view if the images are formed.

B. DIGITAL RADIOGRAPHY:

The method to perform will be similarto normal radiography only but digitalradiography is based on digital detectorsystems in which the x-ray image isdisplayed directly on a computer screenwithout the need for developing chemicalsor intermediate scanning.  The incident x-ray radiation is converted into anequivalent electric charge and then toa digital image through a detector sensor.Compared to other imaging devices flatpanel detector provides high qualitydigital images with better signal to noiseratio and improved dynamic range, which inturn provides high sensitivity forradiographic application.

The above figure shows the setup for andigital radiography

The above figure shows the result thatwas obtained from the digtal radiographyfor a blade.

SENSOR USAGE: Direct digital sensorsare either a charge-coupled device (CCD)or complementary metal oxide semiconductoractive pixel sensor (CMOS-APS).

C. ENDOSCOPIC ULTRASOUND:The basic principle of endoscopic

detection technology is the use of visualmethods to monitor the inner situation ofa sealed object, and then through the

optical image evaluation perform testingand diagnosis. The structure of electronicendoscope is shown in fig with endoscopy,lighting, video processing, video displayand image recording. The biggest featureis the use of CCD components to observeobjects and convert the optical signalsinto digital signals, and then thesesignals are transmitted to the videoprocessing equipment for furtherprocessing, display and data extraction.The electronic endoscope is very importantfor detection of internal damage inengines and other machinery for faultmonitoring and diagnosis.

The above figure shows experimental setup for

SENSOR USAGE: position sensors tolocate the position of part inspected.

D. FLASH RADIOGRPHY:High-sensitive CCD-camera of digital X-

ray television system can be producedusing different CCD-matrices (number ofpixels can make 752x582, 1392х1040 andothers). The camera is equipped with highaperture lens, providing small light lossduring image transfer from X-ray screen toCCD-matrix. Enter of the images intocomputer is carried out through USB 2.0

interface. Efficient single-crystalscreens of Customer-required size are usedas scintillation X-ray screen. Televisioncamera has the capability to operate in amode of adjusted duration of imagecollection to CCD-matrix and cooling isused for reduction of dark component anddark noises at large duration ofcollection. Collection time is severalorders lower than auxiliary time atradiography with intermediate carriers ofinformation.

The above figure shows setup for flashradiography.

The above figure shows results obtainedthrough flash radiography.SENSORS USAGE: used in CCD camera.

II. SENSORS USAGE IN OTHER NDTTESTINGS:

a) AUTOMATATED ULTRASONIC SCANNERS:The scanners have magnetic wheels that

hold them on the vessel. Mild steel tracksclamped to the scan area are used for non-ferromagnetic materials or hightemperature scans. SPI-Matrix offers arange of automated and semi-automatedultrasonic scanning systems. The primarysystem comprises an Olympus MS5800

instrument coupled to a general purpose(GPS) or remotely controlled (GPA)scanner. The scanners operate with a fullrange of ultrasonic probes includingstraight beam, angle beam, tri-element andTOFD. The scanners can be set up withmultiple probes including combinations ofpulse-echo, straight beam and TOFD. Inaddition to these, SPI-Matrix offersprobes for high temperature applicationsand phased array probes. Ultrasonicsignals are acquired and evaluated usingthe versatile advanced software. Thisprovides multiple views of the ultrasonicdata including the raw ‘A-scan’, C-scantop view and sectional views of the areabeing inspected.

SENSOR USAGE: sensors implemented intotal system to detect and the defect andlocation of it.

b) COMPARATIVE VACUUM METHOD:Comparative Vacuum Monitoring (CVM)

offers a novel method for in-situ, real-time monitoring of crack initiation and/orpropagation. CVM has been developed foruse in both a laboratory environment or onoperating equipment. The laboratorytesting equipment has rapidly gainedacceptance in several testing facilitieswithin the aviation industry; often usedto control a fatigue testing program dueto its proven reliability and built-infail-safe properties. A portable unit,with its own data logger, has recentlybeen developed to allow monitoring ofcomponents in operating equipment whereaccess to critical components isdifficult, time consuming and costly.

SENSOR USAGE: CVM sensors used todetect pressure difference.

III. SENSORS APPLICATIONS IN DRONES:

A. MEMS:

The satellite navigation and imageprocessing system for Micro airvehicles by using MEMS sensors.Theproposed system does it by usingthe MEMS sensors which will beattached to the MAV. Also we canfind any remote place by imageprocessing it can take pictures ofspot and its location can bedisplaced with the help of GPSreceiver so by this we can rescuethe people as soon as possible.The satellite navigation uses threeaccelerometer, three gyroscopes,two pressure sensors and twomagneto impedance .Hereaccelerometer and gyroscopes areused to measure the three axisacceleration and angular rates andpressure sensor for air speed andpressure altitude and MagnetoImpedense for measuring thegeomagnetism and calculate theheading angle and here levelingloop is used to measure thereference velocities used tocalculate the error velocities .INS(inertial navigation system) anderror velocities are feed backed tothe basis of gyroscope and then arecorrected and received by GPSconnected to the circuit and

simultaneously the image processingis done by the camera attached tothe MAV sends info to the user thebelow Shows the block diagram ofthe MEMS navigation system.

B. ULTRASONIC SENSORS:To a drone it is very much necessary tohave an autonomous system in total phasesof its flight. So the risks of collisionwith obstacles in the path of autonomousflying systems have to be detected andavoided. It is necessary for drone tocarry a robust controller that respondsquickly enough to reduce the risk ofcollision with obstacle is a need. Anobstacle avoidance technique using low-cost ultrasonic sensors need to be used.They consists of ultrasonic sensors andcontroller board for detection of virtualdistance function and controls the flyingparameters of drone respectively and asimple data fusion method for fusingsensors data measurements. This techniquecan be used to detect and avoid obstaclesin both indoor and outdoor environment. Ultrasonic sensor uses sonar todetermine distance to an object likebats or dolphins do. It offersexcellent non - contact rangedetection with high accuracy andstable readings in an easy-to-usepackage from 2cm to 400 cm. Itsoperation is not affected by sun lightor black materials like Sharp rangefinders are (although acousticallysoft materials like cloth can bedifficult to

detect). It comes complete withultrasonic transmitter and receivermodule.The Ultrasonic sensor is shownin Figure below.

The collision avoidance module divides the area around the quad copter dependenton the measured distance into three zonesfor each direction:a) Far or safe zone (green)b) Close zone (yellow)c) Dangerous zone (red)

The above figure shows the distancezones that are created by thecollision avoidance module.

C. HYPERSPECTRAL SENSORS:Hyper spectral sensors are the imagingsensors developed by Ratheon.corp .Themain advantages of this type of sensorscomes with its ability to detect theinvisible objects by human eye .So whenthey are installed on a drone they can beused to detect the hidden objects such asbombs, archeological objects, in forestsetc,.When light reflects off materials, itproduces a specific chemical signatureunique to that material. If thesignature is in a database of knownmaterials, then a single pixel can

provide enough information to identifya substance. Instead of UV,hyperspectral sensors use reflectionsfrom hundreds of bands in the infraredrange of the electromagnetic spectrum.While cameras (and eyeballs) identifytargets by their shape or by contrastsof light and dark, hyperspectralscanners can collect reflections atvarious IR wavelengths andautomatically determine the materialthat a target is made of.

The above figure shows the differentwavelengths that are obtained byhyperspectral sensors for differentmaterials.

The above figure shows the drone AcesHy which has hyperspectral sensors.

D. WIRELESS SENSORS:These sensors,are helping farmers touse less fertilizers and water, and tocontrol the general condition of theircrops.Drones which carry small camerasable to take near infra-red images ofcrops. Healthy plants are rich inchlorophyll, a pigment that reflectsinfrared quite well: therefore, this

technology, which is already used forscanning by plane, satellite ortractor, has become a precise, non-invasive and more affordable tool tocheck how crops are doing. Moreover,it improves sustainability because itdetects whether a plant needs more orless watering, pesticides or plantfoodsThe sensors are mainly detectingnormalized difference vegetationindex.

The above figure shows the thermalimage of the wheat crop withundiseased plants in a field.E. ULTRASONIC AND THERMAL SENSORS:As it was discussed about NDT in previous

section of thisPaper .so the same application can bedone by using drone by using differentsensors. They are attached to a drone tolocate flaws that are there in the testedpart.The application of this type ofsensors can make the use of NDT mucheasy and reduce the man power to ahuge extent.The use of ultrasound sensors makes adrone to maintain its altitude and canalso be used to determine defectlocation. Whereas the thermal sensorsare used to detect defects on aircraftparts.Thus reducing the man power and timealso by installing it on a drone.

The below figure shows the thermalimage of an aircraft part near wing.

CONCLUSION:There are many NDT techniques that arepresent and also in which the industryis using but most of them are oftraditional and are not able topredict defects accurately .The use ofmedical equipment in NDT was anadvanced technology the was stillunder development. So if the usage ofthis becomes huge the NDT industry canwitness a huge development.The drone that industry was using hasmany advances in terms of sensors thatthey are using. Thus making thereapplications from normal to highlyapplicable areas.

REFERNCES[1] Pauli Vaara ,Jukka Leinonen ,

Technology Survey on NDT of Carbon-fiber Composites ,researchpaper,2012.

[2] David I A Lines Diagnostic SonarLtd.The application of real-timemedical ultrasonic techniques toNDT”a research paper.

[3] P. Rohith, Sai Raman, Azeem Unnisa ,Satellite Navigation and Image Processing by MAV using MEMS,a research paper published in 2014.

[4] Anabarasu B, Ramar S,G. Anitha, Obstacle Detection and Collision Avoidance for MAV Navigation in Indoor and Outdoor Environments using Ultrasonic Sensors, a reserchpaper published in 2014.

[5] Sensors and drones: Hi-tech sentinels for crops: http://phys.org/news/2015-06-sensors-drones-hi-tech-sentinels-crops.html

AUTHORS BIOGRAPHY

Sri Tanusha Kolli ispresently pursuing a degreein field of aeronauticalengineering from MLRinstitute oftechnology,dundigal. Her area

Ravi K is Head - Smart technologies at Motivitylabs Hyderabad. He has 12 years of industry andresearch experience that includes EngineeringInnovation, Problem Solving, Team BuildingDiscover the inventor Leadership, multi-disciplinary engineering, Technology planning.He has obtained M.tech from IIT Mumbai. He hasreceived numerous awards/ rewards forscholastic achievements namely Chief MinisterAndhra Pradesh Gold Medal in 1997, Institution