High Speed OFDM based Image transmission system for Remotely Operated Underwater Vehicle (ROV)

Transcription

1 Volume 117 No , ISSN: (printed version); ISSN: (on-line version) url: ijpam.eu High Speed OFDM based Image transmission system for Remotely Operated Underwater Vehicle (ROV) Naveen H 1, Dr. Sreerama Reddy G M 2, Chetan H 3 1 Assistant Professor, New Horizon College of Engineering, Bangalore, Research Scholar 1, VTU, Belgaum, India. 2 Professor, C Byregowda Institute of Technology, Kolar, India 3 Associate Professor, Research Scholar, VTU, Belgaum, India Abstract The research on wireless underwater communication particularly on acoustic communication has been the core area of research in recent years. The research work focuses on design and modelling of OFDM based image transmission system for miniature remotely operated underwater vehicle (ROV). The research work focused to design and construct an underwater remotely-operated vehicle (ROV), fitted with a 4- axis positioning system, an image transmission system, and a 2-axis (pitch and roll) control system to assist imaging and positional stability. The paper includes the design and development of an ARM Cortex-M3 microcontroller based electronic circuit for the operator interface, and another ARM Cortex-M3 microcontrollerbased electronic circuit that controls the seven DC motors fitted with propellers. The paper includes comparative results of FFT OFDM for high speed image transmission The ROV project ultimately represents an overlap of interests: control systems, underwater imaging system, and electronics. Keywords: OFDM, Underwater Communication, ROV, Image Transmission System 1. Introduction Discovering and exploring new environments is an important human endeavor, a motor for mankind s evolution. One vast environment which is still much unexplored is the underwater world. Crucial for its successful exploration are reliable communication systems. The topic is complex and there are various difficulties in underwater communications. Electromagnetic waves usually are not considered as a solution for underwater communications because their attenuation is too high [4]. Acoustic waves appear as a good alternative, despite some associated negative aspects. The ROV is an Underwater Vehicle used for the underwater explorations, the main advantage of ROV is that it reduces the risks which a diver would have faced while exploring underwater. We are trying to enhance the present features of a regular ROV by adding a SONAR for the underwater scanning and we would also be analyzing the real time images obtained from the onboard camera [5].The interest from the research community in the area of underwater communications has increased recently and this 959

2 work aims to be a contribution to the development of the OFDM based image transmission system for ROV. 2. Literature Survey A particle filter (PF)-based robust navigation with fault diagnosis (FD) is designed for an underwater robot, where 10 failure modes of sensors and thrusters are considered. The nominal underwater robot and its anomaly are described by a switching-mode hidden Markov model by Roger Skjetne [10].An Actuator Failure Tolerant Control Scheme for an Underwater Remotely Operated Vehicle by Maria Letizia Corradini, In the paper an actuator fault-tolerant control scheme, composed of the usual modules performing detection, isolation, accommodation, designed for a class of nonlinear systems, and then applied to an underwater remotely operated vehicle (ROV) used for inspection purposes [7]. Tracking objects in underwater multibeam sonar images by Tina Ruiz, in this work an obstacle detection and tracking algorithm applied to multibeam forwardlooking sonar images. It is used by an obstacle avoidance system to be fitted in a remotely operated underwater vehicle (ROV). The real-time data flow from the sonar output is represented as an image and pre-processed (smoothing filters, region-based segmentation and feature extraction) by the system to identify possible obstacles [11]. A total 3, 90,884 accidental deaths were reported in the country during the year A total of 6, 94,390 cases of Un-Natural Accidents have caused 3, 67,194 deaths and rendered 5, 06,348 people injured during The major un-natural causes of accidental deaths were Road Accidents (37.3%), Railway Accidents and Rail- Road Accidents (7.6%), Poisoning (8.0%), Drowning (8.1%), Sudden Deaths (7.3%) and Fire Accidents (6.7%) deaths have occurred during the year 2011 due to drowning (boat capsize). 3. Proposed Work In the research work, proposed a thorough water imaging equipment that can scan the water front in defined areas and generates images of the water bed, The images which are captured by through water imaging equipment in one ROV will be sent to another ROV using OFDM Communication link. The system will be based on sonar imaging technology that can beam sonar signals which scans the water front in defined areas and automatically generates the images Which can be sent with high speed to another ROV placed at long distance. 960

3 OFDM Communication Link Remotely Operated Underwater Vehicle Remotely Operated Underwater Vehicle Fig 1. OFDM based Image Transmission between two ROV 4. ROV Implementation Our main device consists of three separate sectors: 1) Physical structure 2) Top controller and Bottom controller 3) Software Implementation A. Physical Structure Frame Design and Construction The purpose of the frame is to support the water-proof enclosure, the thruster motors, and any trimming weights. The principle design goal for the frame, taking into account thruster and enclosure positioning and support, was to ensure there was maximum water flow through the open frame, to therefore minimize drag. Fig 2. Remotely Operated Vehicle Block Diagram 961

4 B. Top Controller and Bottom Controller Top Controller The primary purpose of the top controller is to act as the operator control interface. From the operator s point-of-view, they need to be able to control the position of the ROV in the water on any one of four axes, as easily as possible, and receive timely feedback from the ROV of its position and the nature of the environment it is in. Fig 3. Top Controller Block Diagram Bottom Controller The primary purpose of the bottom controller is operation of the thrusters and lights, as instructed by the operator using the top controller. There are 7 thrusters: 4 requiring unidirectional control, and 3 requiring bi-directional control. There is also an integrated inertial measurement unit (IMU) for the self-stabilizing control system. Fig 4. Bottom Controller Block Diagram C Software Implementation The web cam used for testing delivers a RGB output that is converted into single value intensity. The frame difference is done between current frame and one timestep-delayed frame. The rate of the video being 30 frames per second the time step is 1/30 of a second. Tracking is implemented following the model proposed by MATLAB Simulink. 962

5 Fig 5. Simulink Block Diagram for Image Capturing 6. OFDM Image Transmission System In the gray scale image transmission is done using a FFT based OFDM system in AWGN channel and results are compared for four different M-PSK modulation scheme with different SNR. We reconstruct our transmitted signal at receiver; in both systems by minimizing the error by efficient and robust technique. Results are compared for different modulation technique with different SNR value. The total number of BER, Pixel error, average phase error, total time taken for transmission of image, PSNR value are calculated and are described here. System Configurations and Parameters The user input variables include: 1) Input file an 8-bit grayscale (256 gray levels) bitmap file (*.bmp); 2) IFFT size an integer of a power of two; 3) Number of carriers not greater than [(IFFT size)/2 2]; 4) Digital modulation method BPSK, QPSK, 16-PSK, or 256-PSK; 5) Signal peak power clipping in db; 6) Signal-to-Noise Ratio in db. The captured image by one ROV will be sent to another ROV using FFT based OFDM system, The table 1 gives the comparison result of different modulation techniques and it shows that 64-PSK provides fastest image transmission i.e 3.7 sec compared to all other modulation techniques. It also shows that SNR, BER, Pixel Error achieved for different modulation techniques. 963

6 Table 1: Comparison of Different modulation Techniques for OFDM image Transmission IFFT = 1024, Carrier = 400,Amplitude Clipping = 3 db, Source image = 600 X 900 Modulation SNR BER Pixel Transmit Receive Time Type Error Time 256-PSK PSK PSK PSK PSK PSK PSK PSK PSK PSK PSK PSK QPSK QPSK QPSK QPSK QPSK QPSK BPSK BPSK BPSK BPSK BPSK BPSK The below figure shows the BER V/S M-PSK techniques, Fig 6. BER V/S M-PSK 964

7 Fig 7. BER V/S SNR Fig 8. Pixel Error V/S SNR Fig 9: Receive Time V/S M-PSK 965

8 Fig 10: Transmit Time V/S M-PSK 7. Result and Snapshots To Build an underwater vehicle fitted with thrusters for horizontal and vertical positioning Fig 11: Underwater ROV fitted with Thrusters Building of microcontroller-based electronic circuitry for operating the thrusters Fig 12. Bottom and Top Controller of ROV 966

9 a) Original Image b) 0 SNR FFT = 64 c)15 SNR FFT=256 d) 0 SNR FFT =1024 e) 70 SNR FFT = 1024 f) 50 SNR FFT =1024 Fig 13. OFDM Image Transmission with Different SNR and FFT Size 8. Conclusion and Future Development 8.1. Conclusion The proposed system will be designed and developed as a prototype and will be used in demonstration of its capabilities. Technology transfer can be taken up with interested companies in commercializing the products. The developed product can be used by Indian Navy for monitoring Marine life and to transfer the high speed images from one ROV to Other ROV. For transmission of High speed image, We use FFT based OFDM. Results are compared for different modulation technique with different SNR value and also BER is computed for different SNR value. The results shows that the Time taken for image transmission using BPSK is more and that of 256-PSK modulation is very less. Comparison result are given in this papers wrt BER vr SNR, Pixel Error Vr SNR. 967

10 8.2 Future Development The project can be analyzed for different input source data like audio, video or text and can be compared its performance against different modulation techniques. The project can be explored for DWT based OFDM and DTCDWT based OFDM and the comparison can be done with FFT based OFDM for performance analysis. The project can be analyzed for underwater channel which uses Rayleigh or Rician Channel. In- and out-of-water testing of the vehicle has been an ongoing process throughout the entire development process. In-water measurements to identify the vehicles dynamic characteristics are still currently underway and have not been completed. 9. ACKNOWLEDGEMENTS We like to thank Chetan H, Assistant Professor, CMRIT for guiding me in making the paper. We would like to thank Prof. Preeta Sharan, HOD, Dept. of ECE, The Oxford college of Engineering for her valuable support and giving inputs in making the paper. We like to express our sincere thanks to all the Faculty members of New Horizon College of Engineering for their support in making the paper. 10. References [1] Naveen H and Dr.Sreerama Reddy G M, Performance analysis of FFT based OFDM and DWT based OFDM for Underwater Acoustic Communication Indian Journal of Science and Technology, Vol 10(36), September 2017, ISSN (Online): (2017) [2] Naveen H and Dr.Sreerama Reddy G M, Multipath Effect of different modulation schemes for underwater acoustic communication IndiaCom 2017, IEEE Conference on Computing for sustainable global development, New Delhi (2017). [3] Diogo Mendes, A MATLAB/Simulink model to evaluate underwater acoustic. Masters thesis, Universidade do Minho, Portugal, December (2011) [4] Kalangi Pullarao Prasanth. Modelling and simulation of an underwater acoustic communication channel. Masters thesis, University of applied sciences Bremen, Germany, (2004). [5] M. Stojanovic. Recent advances in high-speed underwater acoustic communications. Oceanic Engineering, IEEE Journal of, 21(2):125136, (1996). [6] Dario Pompili and Ian F. Akyildiz. Overview of networking protocols for underwater wireless communications. Comm. Mag., 47(1):97102, January (2009). [7] M. Schroeder, Thomas D. Rossing, F. Dunn, W. M. Hartmann, D. M. Campbell, and N. H. Fletcher. Springer Handbook of Acoustics. Springer Publishing Company, Incorporated, 1st edition, (2007) [8] Gunilla Burrowes and Jamil Y. Khan. Short-range underwater acoustic communication networks. Autonomous Underwater Vehicles, Mr. Nuno Cruz (Ed.), (2011) 968

11 [9] A.D. Waite. Sonar for practising engineers. Wiley, (2002) [10] R.J. Urick. Principles of underwater sound. McGraw-Hill, (1983) [11] Mari Carmen Domingo. Overview of channel models for underwater wireless communication networks. Phys. Commun., 1(3):163182, September (2008). [12] William H. Thorp. Analytic description of the low-frequency attenuation coefficient. The Journal of the Acoustical Society of America, 42(1):270270, (1967). Authors Naveen H Naveen H Received B E Degree, M.Tech Degree from Visveswaraih Technological University, Belgaum, India in 2009 and 2011 respectively. Currently Pursuing PhD in VTU, Belgaum. He is working with New Horizon College of Engineering, Bangalore. He has published technical papers in reputed conference and journals. His Area of interest include OFDM, WSN, Communication system, Embedded system for Communication, PSOC, Embedded system for VLSI and DSP. Dr. Sreerama Reddy G M Dr.Sreerama Reddy G M Received B E Degree from Gulbarga University, Gulbarga,India in 1990, M E degree from UVCE, Bangalore, India in 1996, PhD degree from JNTU, Hydrabad, India in He Worked as Assistant Professor in SJCIT, Karnataka from He headed the Department of ECE in SVCET, Chittor from He was Principal in M S Engineering College, Bangalore from He is presently working in CBIT, Kolar, Karnataka as Professor and Head of ECE Dept. He has published two technical Books, More than 30 research papers in international conference and journals. He is Life member in ISTE (LMISTE), he is Fellow Member in IETE (FIETE), Member in IE (MIE). His Research interest include Low Power VLSI, Logic Design, and VLSI Design. 969

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