TigerCENSE: Wireless Image Sensor Network to Monitor Tiger
Contents
1. References 1 Yasuda M Kawakami K New method of monitoring remote wildlife via the Internet Ecological Research 17 119 124 2002 2 Nath L Camera Trap in Conservation http www nfwf org AM Template cfm Section HomexTEMPLATE CM ContentDisplay cfm amp CONTENTID 8749 3 http www panda org what_we_do endangered_species tigers 4 http www iucnredlist org details 15955 0 5 Staving Off Extinction A Decade of Investments to Save the World s Last Wild Tigers 1995 2004 http www nfwf org Content ContentFolders NationalFishandWildlife Foundation ConservationLibrary ProgramEvaluations Staving_off_ 6 McDougal C The Face of the Tiger Rivington Books London 1977 7 http www panda org what_we_do endangered_species tigers tiger_ solutions 8 PIR Parallax 555 18017 Datasheet http www parallax com detail asp product_id 555 28027 9 Texas Instrument TPS2092 Datasheet http www ti com lit gpn tps2092 10 COMedia Ltd s C328RS User Manual http www electronics123 net amazon datasheet C328R_UM pdf 11 Lens of camera http www electronics123 net amazon datasheet C328R pdf 24 12 13 14 15 16 17 18 19 20 21 22 R Bagree et al DS3231 RTC Datasheet http www maxim ic com quick_view2 cfm qv_pk 4627 XBee PRO OEM RF Modules Product manual http www maxstream net products XBee product manual_XBee_OEM_RFModules pdf micro SD Card Datasheet2. image sensor 1 Introduction Most of the WSN applications have depended on sensors such as light and tem perature etc which produce small amount of data per sample However in recent years technological advances especially in CMOS have made it possible to have very small low powered and cheap image sensors integrated to WSN enabling us to collect valuable visual information of the target object and its surroundings These image sensors produce large data per sample based on im age size Due to this Wireless Image Sensor Network WiSN has emerged as a new field with its own application areas as well as challenges One of its most promising applications is monitoring wildlife species Corresponding author 1 This project is partially funded by Wildlife Institute of India Dehradun P J Marron et al Eds REALWSN 2010 LNCS 6511 pp 1 2010 Springer Verlag Berlin Heidelberg 2010 14 R Bagree et al Traditional methods of wildlife monitoring are largely based on statistical methods and data collected by ground surveys i Though these methods usu ally yield extensive data for a given animal and its habitat they are time con suming expensive and unauthenticated Some methods such as the traditional pugmark census are not even reliable enough 2 Above all most of the en dangered or critically endangered species live in remote arid and inaccessible landscape Monitoring them their behavior their status and dis
3. where standard existing technology can be used This section describes the platform developed and used for our experiments Hardware system architecture of tiger CENSE node is as depicted in Figure While describing the hardware used we will also discuss the flow of the software and the challenges faced during its development When the system is in idle state with no movements of animal all the hard ware components will be in power saving or sleep mode except the PIR sensor When an intrusion is detected PIR sends an interrupt to the micro controller and the system gets into its active state The PIR Sensor is a pyro electric device that detects the motion by measuring changes in the infrared levels emitted by surrounding objects PIR We use Parallax INC 555 28027 8 PIR sensor which works from 3 3 to 5V and draws less then 100 uA current Also it is less prone to false triggers 18 R Bagree et al when compared to active beam interrupted motion detectors Active beam based system may get triggered by a very small object e g leaves falling of a tree It has the Fresnel lens with the viewing angle of 90 degree and a range of approxi mately 20 feet At start up the PIR requires a warm up time in order to learn its environment or in other words creating the heat map of the environment This start up time could be anywhere from 10 60 seconds After this whenever PIR sensor detects any sudden change in its heat map in other words
4. a Power MOSFET with very small ON time resistance ON time resistance is of particular importance as we are drawing very high current of 2 5A Even few milliohms of ON resistance can result in significant voltage drop across LEDs which will reduce its intensity severely Power MOSFET The Power MOSFET STB100NFO3L 19 from ST Micro electronics has been used for the said task Its ON resistance is less than 3 2 m2 with Gate threshold voltage is as low as 1 7V Tigers mostly move in night time and to illuminate the animal we are using IR LEDs But since the size of the trap is of much concern we need to use least no of LEDs possible This requires very high radiant intensity low forward voltage LEDs IR LED We use TSHG5210 20 which is the strongest high intensity IR LED available in the market from Vishay Semiconductors This is an infrared 850nm emitting diode with forward voltage of 1 5V In pulse mode its radiant power is 2300mW sr Its angle of half intensity is 10 degree However one may need wider beam angle than what this provides Right now the system uses 12 LEDs in parallel We are working on the ways to reduce the number of LEDs to about 5 6 by improving the charge buffer system We selected parallel configuration as it is easy to provide a large current instead of high voltage Also in such configuration each LED is independent of the other and failure of one LED does not disturb the function of whole flash Learning
5. continuous shots has been found out to be Is It is dictated by the time to transfer the data from Image Sensor to Micro SD card and can be reduced by buffering it in a fast memory if one needs to collect a burst of images To find out the minimum suitable ON time for the IR flash to capture the stripes clearly on its body we deployed a prototype box as shown in Figure 3 near the cage of a tiger in Kankaria Zoo Ahmedabad Gujarat We programmed the node to take pictures with increasing ON time starting from 10ms to 70ms with an increment of 10ms Figure 4 shows some of the photographs taken by the node in the dark using an IR Flash From the experiments we concluded that an ON time of 30ms is sufficient to get a reasonable quality image with clear stripes We need flash time to be as low as possible to reduce blur due to motion Some commercial digital cameras use 125 ms flash time which leads to significant blare to the extent of image being useless 6 Conclusion This paper presents an operational prototype for wildlife monitoring using WiSN tiger CENSE is compact non intrusive energy efficient and reliable sensing de vice It not only has all the capabilities of traditional traps but has also addressed most of the drawbacks of them Integrated development has led to minimum de lay of 250 ms The software protocols and the hardware implementation have TigerCENSE Wireless Image Sensor Network 23 all been carefully crafted to optim
6. from the experience for wildCENSE 21 project the node has been designed employing numerous noise reduction techniques To reduce the ADC noise a LC filter L 10mH and C 0 1uF has been added to the ADC pins of the micro controller Also the AVcc is connected to the main power supply TigerCENSE Wireless Image Sensor Network 2l n 1y Gi MMU EEA i 2 ee eraan j ry p Del ows et RoN tiat ME GL PHPH H I i A 3 22gieite JYOTI 0000 zoi Fig 2 tigerCENSE node Front and Rear view without any in between fan out lines to reduce noise 22 The whole PCB has copper pouring to keep the noise at a minimum level as also to dissipate any heat generated by the node Figure 2 depicts the PCB made for the node The size of the populated PCB is 3 8 x 5 6 x 3 1cm weighing only 43 gms excluding power supply and enclosure 5 Experimental Results Based on the expected speed of movement and width of walkways assumed 10 feet and distance of node from walkway to be 10 feet a delay of 1 8 sec is kept Fig 3 Prototype box used for testing 22 R Bagree et al fa b cd Fig 4 Photograph clicked using IR Flash in dark night between the PIR interrupt and capturing a photograph of the object Minimum delay achievable seems to be 250 ms It is extremely small time as compared to the response time of traditional traps which ranges into few seconds Also minimum delay between two
7. need micro controller switches on the high intensity Infra Red Flash using a power MOSFET All the photographs need to be time stamped along with the node ID To keep track of time on the node we are using a Real Time Clock RTC When the node is powered on for the first time it needs to be in the range of a base station to synchronize with the system time Once the time is set the battery backed RTC keeps the timing information for years and corrects any drift each time node communicates with the base Real Time Clock RTC We use DS3231 12 as RTC which is one of the industry s most accurate RTC Its power consumption is 110 uA at 3 3V It has integrated temperature compensated crystal oscillator TCXO and I C interfacing A radio transceiver has been used to transfer the collected photographs and other data health information of the node to the gateway base station for on ward transmission to the server Radio Transceiver Communication module XBee Pro i3 from Digi Key is used which is based on ZigBee TEEE 802 15 4 standard It operates at 2 4 GHz only freely available ISM band in India providing a range of more than a kilometer Its RF data rate is 250 Kbps While using this frequency results in TigerCENSE Wireless Image Sensor Network 19 higher power consumption for same range compared to 900 MHz we gain in terms of much higher data rate and smaller compact antenna Low cost low power and ease of use are among
8. poaching activities etc Most of the available cam era traps use independent commercially available camera modules that may be digital or film based usually triggered by a motion detector In the very old days trip wires and pressure pads were used to trigger cameras 2 Modern motion detectors are based on infrared and may be active or passive Active infrared based motion detectors send out an infrared beam to a receptor located some distance away When any object obstructs this beam s path the detector triggers and camera captures the photograph Whereas a PIR sensor tracks heat change in the surrounding When any infrared emitting object passes in front of the detector it detects the motion Also the modules that aim for night photography usually come equipped with either white or infrared flash Some of the commercial cameras use almost 64 LEDs making them much bigger and consume lot of power These systems usually use strobes and wires to interconnect the motion detec tor the independent camera and to setup an automatic image capturing system This makes their size quite bulky and difficult to camouflage making it highly prone to stealing by people or being damaged by animals Also presently most TigerCENSE Wireless Image Sensor Network 15 of the commercially available traps do not have a local wireless network link Al though few of the traps do communicate with satellite but because of the leased satellite link they cost heavil
9. recognition and density estimates activity cycles behavior seasonal variation in movement and abundance and also allows for comparisons to be made between areas 2 tiger CENSE is an attempt in the similar direction and provides images in an inexpensive power and time efficient manner Nodes are setup by researchers along each bifurcation of the tiger trail to help figure out the path taken by tiger Whenever a tiger gets in the field of view of PIR sensor an interrupt is generated and the image sensor will capture the photograph As tiger moves mostly in night an infrared flash is integrated in the system The photograph is time stamped and gets stored on a micro SD card along with node ID Once the communication with gateway or next hop neighbor is available it would transfer the image wirelessly using a radio transceiver As the memory size of the micro SD card can be increased the upper limit of photographs that can be saved is adjustable Also wireless connectivity and solar recharging for battery help in minimum anthropogenic disturbance which otherwise would have been required for data collection and to change the power battery Though camera traps technology have been in use for quite long time but still it is not fully explored and suffer some major drawbacks Besides having all the pros of old traps tiger CENSE has been designed keeping the following drawbacks explained further as its prime design challenges 16 R Bagree e
10. TigerCENSE Wireless Image Sensor Network to Monitor Tiger Movement Ravi Bagree Vishwas Raj Jain Aman Kumar and Prabhat Ranjan Dhirubhai Ambani Institute of Information and Communication Technology Gandhinagar India 382007 ravi_bagree vishwas_jain aman_kumar prabhat_ranjan daiict ac in Abstract Wireless Sensor Network WSN in combination with image sensors opens plethora of opportunities in the wildlife tracking It pro vides a glimpse into previously unseen remote and inaccessible world of some of the most endangered species on earth tigerCENSE Fis such an attempt to put sensor network technology in conserving one of the rarest and most elusive big cat species The node triggered by the Passive In frared PIR sensor captures the image of tiger using a CMOS image sensor and stores it in an external memory chip To avoid any disturbance to animal the node uses an Infrared IR flash instead of white flash to illuminate the target at night The stored images get transferred to the base station via radio transceiver This is transferred to the database server through Internet links for analysis by wildlife researchers A solar energy harvesting system for recharging node s batteries is being added to avoid frequent human visit to change the batteries making it highly non intrusive system Keywords Camera Trap Wireless Sensor Network Image Sensor Net work wildlife tracking Intrusion detection CMOS camera IR flash
11. e number of shots in burst mode delay between two adjacent shots etc of the traps Remotely changing of parameter further reduces the visit and labor of researchers Fail Proof against False Interrupts In spring when many trees shed their leaves in preparation for new foliage active IR sensor gives lot of false interrupts Each momentary break in the beam caused by a leaf floating across the path may result in a useless picture being taken tiger CENSE needs to take care of it as this may consume large amount of power for no good reason Health Information of Traps Presently once the trap is deployed in the field there is no way to know about its health and other parameters The film or the battery might have been exhausted long back but the researchers would not know Also the camera might stop working because of some technical problems it might get stolen or may have been damaged by an animal but it will remain unknown until someone visits it This makes the trap highly inefficient as it may loose important information Energy Harvesting Present traps consume enormous power and need the battery replacement at regular interval This not only leads to frequent visit of the researchers but also the maintenance cost goes up This requires for an efficient power supply with a recharging mechanism The Solar recharging system could be an excellent solution to it With careful energy management policy supplemented by harvesting the energy req
12. gy consumption profile and almost similar input supply range with 3 3V as the common voltage The decision of using a common voltage 3 3V not only made the power supply 20 R Bagree et al for the node simple but also saved energy which otherwise would have been wasted in regulating it for different voltages With time the battery voltage will reduce from 3 7V to 2 7V But the node needs a constant voltage supply of 3 3V so we need a buck boost DC converter to regulate the battery voltage Buck Boost Converter To utilize the battery power to the maximum a DC DC converter TPS63001 17 buck boost converter from Texas Instruments is used It provides a constant 3 3V output with a maximum of 1 8A of current being rated up to 96 efficient The same battery will be used to power the IR LEDs These LEDs will be used in pulse mode with high time of 30ms To get high intensity rays we need to supply very large current approx 3 0 A for this pulse duration As a battery may not supply such large current we need buffer storage of electric charge in between Super capacitor is the best option for this task We are using two super capacitors in series to get the required voltage Super Capacitor Super capacitor TS12S R 18 is used which is highly com pact and high density capacitor with capacity of 10F at 2 5V Its self discharge rate is very low and can supply maximum of 4 5A of current To switch on the LEDs for such a short time we need
13. http www sparkfun com datasheets Prototyping microsD_Spec pdf Atmel ATMegal281 Datasheet http www atmel com dyn resources prod_ documents doc2549 pdf Polymer Lithium Ion Batteries 6Ah Datasheet http www sparkfun com datasheets Batteries UnionBattery 2000mAh pdf Texas Instruments TPS63001 Datasheet http www ti com lit gpn tps63001 Suntan Super capacitor TS125 R Datasheet http www sparkfun com datasheets Components TS12S R pdf ST microelectronics Power MOSFET STBIOONFO3L Datasheet http www st com stonline products literature ds 9307 pdf Vishay Semiconductor IR LEDs TSHG5210 Datasheet http www vishay com docs 81810 tshg5210 pdf Jain V R Bagree R Kumar A Ranjan P wildCENSE GPS base Animal Tracking System In International Conference on Intelligent Sensors Sensor Net works and Information Processing Sydney December 15 16 2008 Innovative Techniques for Extremely Low Power Consumption with 8 bit Micro controllers http www atmel com dyn resources prod_documents doc7903 pdf
14. it detects an intrusion it pulls up its output pin giving an interrupt to the micro controller The interrupt from the PIR wakes up the micro controller and it initializes the image sensor to take the photograph The initialization of image sensor happens in two steps In the first step the micro controller enables the power to the image sensor using a power switch TPS2092 9 The power switch is being used to conserve the power which otherwise would be wasted as the quiescent power of the image sensor In the second step the micro controller sends commands to the image sensor to customize setting and to capture the image Image Sensor COMedia Ltd s C328R image sensor module is used which performs as a JPEG compressed low cost low powered still camera It interfaces with the micro controller using the serial communication It works on 3 3V with 60mA of current As we are using IR flash to illuminate the object we use a lens without IR filter CMOS image sensors are typically sensitive to 1000 nm and use of IR LED in 850 nm to 950 nm range to illuminate the target is possible The lens configuration can also be altered to vary the Field of View FOV of the camera Currently we are using the lens with FOV of 60 degree Before taking the photograph the micro controller reads the output of a photo resistor interfaced to its ADC pin to sense whether the ambient light is sufficient for the image or if flash is required Depending on the
15. ize the systems energy requirement Further utilizing the solar recharging mechanism node lifetime would be enhanced In future we can also add some micro climatic sensors in order to collect ambiance information Also to reduce the amount of wireless data transfer we can deploy in situ digital signal processing technique This will help us save both power and time which is highly crucial for the success of the system tiger CENSE has been mainly developed to help in the research and conserving tigers Besides the use for conducting a census camera traps can be very useful for many management tasks It can be used for human surveillance as well In the past traps have photographed poaching parties Although due to latency in collecting the photograph target animal prey were not saved but it eventually led to the arrest and conviction of known offenders Acknowledgment We would like to thank Bharat Jethwa of GEER foundation Gandhinagar for always being available when needed Discussion with WII researchers P R Sinha Director S P Goyal K Sankar B Pandav Q Qureshi and others have been very helpful We would also like to thank R K Sahu Superintendent and others of Kankaria Zoo Ahmedabad for giving us permission to carry out trials as well as helping in the process We would also like to acknowledge tremendous contribution made by earlier team members of tigerCENSE especially Amrit Panda Rigveda Kadam Dheeraj Kota and Hemant Kavadiya
16. nit of our design It has 4K bytes of EEPROM and 8K bytes of SRAM The availability of 2 USART ports enables independent communication of Camera and Radio transceiver with the core processing unit The internal res onator is not accurate enough for serial communication so an external crystal of 1 83728 MHz is used Limiting baud error to zero percent An efficient energy power supply and management policy has been designed to achieve true non intrusive nature of tigerCENSE Energy efficiency is achieved by using very low loss DC DC converter and other components such as power switch to switch off all the devices whose sleep mode power consumption is not sufficiently low All the peripherals are switched off or kept in sleeping mode except PIR sensor in normal mode The system is powered by a re chargeable Li poly battery Solar energy harvesting is being added to further enhance the node life The battery s capacity should be sufficient enough to power the node for at least one month We are carrying out tests to determine node s actual life time in working environment Battery We are using a 6AH Li poly battery 16 These are very slim extremely light weight batteries based on the new Polymer Lithium Ion chemistry Its output voltage is 3 7V with 2 7V cut off voltage Also it has 2C discharge rate Designing a simple power supply for such complex system was a challenge All components and sensors were carefully selected to have low ener
17. t al Response Time The time delay between PIR interrupt and capturing the photograph is very critical Because of large response time of many traditional traps fast moving animals do not get captured tigerCENSE system needs to reduce this time to around one second to overcome the said drawback Size and Cost Traditional traps were bulky and costly Developing a cus tomized system with an integrated image sensor is desirable as this will drasti cally reduce the size and the cost Also presently the number of LEDs used to illuminate the animal is very high We could make an illuminator with fewer but brighter and more efficient LEDs Disturbance to Animals To allow night photography IR flash is recom mended as white flash will startle the animal resulting in the abandonment of the path Also mechanical shutter produces a click sound while taking a photograph This needs to be avoided as this makes the animal cautious of its surrounding and to behave abnormally Automated Data Transmission and Local Storage A wireless connectiv ity is required which allows the nodes to be deployed in very remote areas and it will also reduce human visit to the forest to a great extent Also to compensate for any link failure due to environment or other failures the node should have sufficient external memory to store the data for a month Remote Configuration Researchers need to go to the field each time they need to change any parameter lik
18. the other advantages It also provides five sleep modes to meet various needs of different applications We use lowest power sleep mode as it is not a time but power critical system Recently introduced XBee Pro 2 5 version supports multihop transfer of data The image can be transferred using multihop facility provided by XBee Pro 2 5 But there are chances because of bad weather or some other technical problem establishing a communication link is not always possible for a sensor node especially those deployed in remote areas So the captured image needs to be stored in some storage device Typically the size of a photograph is 60KB So we cannot use an internal memory and need an external storage Micro SD Card We have used micro Secure Digital SD 14 card commonly used in mobile phones which can be interfaced with micro controller using SPI bus The card can be manually removed and the images can be transferred into a computer phone or even a digital camera for viewing The conventional method of writing data into external flash memory restricts the user from viewing the images with such ease The storage capacity of the micro SD card is adjustable depending on the activity of the animal at the location Currently we are using a 2GB card All the decision making and controlling of components on the node is done centrally by the micro controller Micro controller ATMega1281V 15 with 128K bytes program memory is the core processing u
19. tribution be comes life threatening tiger CENSE is an attempt in this direction to make such tracking more authentic automated non intrusive less expensive and safe Un der tigerCENSE project we are primarily focusing on collecting images of tigers along with its time date and location to identify their movement patterns and making it available to the researchers in an easy manner Tiger is the largest of all the Asian big cats and one of the most threatened species 3 Throughout their range in Asia tiger populations are threatened either directly from poaching or from habitat and prey loss 4 Once having the population count above one million is now struggling for its survival with the mere population of 3 402 5 140 across the world 4 In last few decades number of conservation programs have been proposed by various countries and other international organizations They have been working on many possible solutions like restoring habitat monitoring populations anti poaching laws etc and millions of dollars have been invested for the same 5 But common to all the solutions is monitoring the status and population distribution information of the tigers 2 Available Technology The advent of advance camera trap technology has revolutionized conservation plans for wildlife It helped to uncover invaluable information about rare species and their habitats which can be shared with local governments when mak ing land use decisions anti
20. uirements can be met TigerCENSE Wireless Image Sensor Network 17 IR LEDs TSHG5210 PIR Sensor Parallax INC Real Time Clock 555 28027 uController DS 3231B ATMega1281V 8bit RISC 128kB waco up A Flash 8KB RAM Interrupt Photo Y 4KB EEPROM Power MOSFET STB100NFO3L Micro SD Card 2GB SSS Transceiver Resistor XBEE Pro Camera 2 4Ghz Radio Fig 1 tigereCENSE Hardware setup depicting various components their interfacing and power supply 4 System Overview Broadly the tiger CENSE system is divided like any other traditional WSN in the hardware related system software and drivers middle ware servers with data log ging and web hosting services and finally the browser based visualization software We plan to use radio transceivers capable of communicating over 1 5 km in the free space The range may get affected due to surroundings but would still be sufficient to allow node to node communication and multihopping of data Most of the nodes would be in the valley but to provide link to Internet we would need to use GPRS links using mobile communication infrastructure As mobile signals would not be available in the valley we would need to setup a 4 5 km directional link between a gateway in the valley and that on the hills Using mobile signal available on the hills we would be able to transfer the data to servers using GPRS Our focus in this paper is more on the node development and not on the rest of the system
21. y In this paper we are proposing the system tiger CENSE which has been able to resolve many of the problems faced by these traditional camera traps Here we will be discussing the hardware and software design architecture of the tiger CENSE system at the node base and network levels In particular the paper embodies the issues and constraints which were met during the design and testing of the system Section of the paper discusses the design parameters taken into account for tigerCENSE Overview of the system is described in Section 4 covering the hardware and software aspects of the system Experience gained system perfor mance and our field testing results are covered in Section 5 Finally we conclude by enumerating the challenges and experience gained from inception to trials 3 tigerCENSE To make an informed decision researchers need to know the status and distri bution pattern of tigers in the area of interest They collect information using pugmark DNA technique or through camera traps As human beings have fin gerprints as their unique identity characteristic stripe patterns on cat s body differ from one individual to another and from one side of the cat s body to the other 6 In fact there are no tigers with identical markings Wildlife re searchers are mainly interested in these unique stripes pattern It allows them to extract potential information on the presence of species their home range sizes individual
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