The twenty sixth Student Poster Program of the OCEANS Conference series was held as part of OCEANS’10 IEEE Sydney. The program was organized by Dr. Stefan Williams, of the University of Sydney, and was supported by a grant from ONR Global. Sixty one abstracts were received and twenty one were accepted for presentation. Nineteen students were invited to participate. Two students had two posters accepted and displayed. Ten countries were represented; France, Norway, New Zealand, India, Spain, USA, Australia, Scotland, Germany and Japan. The posters were displayed in the Exhibition Hall where the conference attendees passed by and observed them. The students gave short presentations describing their work at three scheduled session on Tuesday afternoon and Wednesday morning. This facilitated the judging and also gave the students an opportunity to make a group presentation.

Dr. Stefan Williams, Student Program Chair

The judging was completed by noon on Wednesday and the awards were presented at the Gala Function in Luna Park that evening. Dr. Williams and Mr. Norman D. Miller reviewed the work of the judges and selected the winning posters. At the Gala Function, the Conference Chairman, Dr. Brian Ferguson called Mr. Miller to relate the history of the program and to present the certificates and award. Mr. Miller noted that to date 482 posters had been displayed at the OCEANS Conferences since the program began at OCEANS ’89 in Seattle. Dr. Williams called the students forward and each received a certificate for their participation from Mr. Miller. The last six students called were the award winners. In addition to their participation certificate they received a monetary award. The students were assembled on stage for group photos and then Mr. Miller proclaimed that they were now members of the “OCEANS Student Poster Alumni Association” and asked the audience to recognize the students by their applause.   

The roster of students and their poster titles is listed below along with an abstract of their paper. A short bio is included for those who provided one.

Anuj Sehgal, Jacobs University, Germany – Modeling Underwater Acoustic Communications for Multi-Robot Missions in a Robotics Simulator
     Abstract—Missions involving multiple Autonomous Underwater Vehicles (AUVs) are gaining increasing popularity with the advent of better control mechanisms and availability of acoustic modems that allow for cooperative networked tasks to be carried out by Unmanned Underwater Vehicles (UUVs). However, high costs associated with offshore testing and the lack of useful tools to accurately simulate multi-AUV tasks has been a hindrance to exploiting the full potential of the field. Even though there exist a few simulators for modeling a single AUV, there is virtually no simulation tool available that allows modeling of acoustically networked communications between multiple AUVs by accurately characterizing the underwater acoustic channel. In this paper we present an overview on modeling of the underwater acoustic channel, taking into account the high degree of local variability of ocean conditions, multi-path echoes and ambient noise, within the framework of an underwater acoustic communications server for the Unified System for Automation and Robotics Simulator (USARSim) robotics simulator.

Anuj Sehgal, Jacobs University, Germany – Effects of Climate Change and Anthropogenic Ocean Acidification on Underwater Acoustic Communications
     Abstract—Global climate change is a widely accepted phenomenon and it is well understood that it is also leading to changes in the oceanic conditions. Increased industrial activities have also led to anthropogenic ocean acidification, the effects of which, on marine ecosystems, is a vigorously investigated topic. However, the impact of these phenomenon on underwater acoustic communication has not been investigated thoroughly. Fluctuations in ambient ocean conditions, such as salinity, acidity and temperature can lead to changes in the underwater acoustic channel performance. Since both marine mammals and man-made underwater wireless networks depend upon acoustic communications it is important to understand the effects in this context as well. An insight into the effects of climate change and anthropogenic ocean acidification could aid in designing better communication systems and also help explain some observed changes in marine mammal communication behavior. In this paper we present the results of a study conducted to better understand the effects of global climate change. Along with a brief presentation of the mathematical model, results of increasing temperature and acidity are discussed and effects on digital and marine mammal communication are both explored.

Edmund Brekke, Unik, Norway – The Signal-to-Noise Ratio of Human Divers
     Edmund Brekke was born on October 23, 1980 in Trondheim, Norway. He received the M.S. degree from the Norwegian University of Science and Technology (NTNU) in industrial mathematics in 2005. His research interests are in detection theory, target tracking, seismic inversion and signal processing. He has recently submitted his Ph.D. thesis covering “Clutter Mitigation for Target Tracking”, and expects to receive the Ph.D. degree from NTNU during the remainder of this year. He is currently looking for job opportunities in Singapore.
     Abstract—A challenging problem in underwater acoustics is the detection and tracking of human divers. In order to assess the suitability of different tracking methods on this problem, an evaluation of the signal-to-noise ratio (SNR) is required. This paper investigates the SNR of a human diver using two approaches. The first approach is a moment-based target power estimator which uses the amplitudes of measurements validated by the tracking method. The second approach is by means of the receiving operating characteristic (ROC). The integrated Probabilistic Data Association (IPDA) is used to track the diver. To the best of our knowledge, this is the first well-documented implementation of the IPDA on real data.

Edmund Brekke, Unik, Norway – Target Tracking in State Dependent Wake Clutter
     Abstract—Tracking methods attempt to follow the movement of a target of interest while suppressing irrelevant clutter. A particularly troublesome source of clutter is wakes that appear behind the target. This problem arises in sonar tracking of human divers, in the tracking of boats using surveillance radars, and also in radar tracking of ballistic missiles. Previous research has integrated a solution to this problem in the popular Probabilistic Data Association filter (PDAF). This paper proposes a new solution to this problem in the same framework. While previous research has used an approach described as probabilistic editing, the new solution solves the wake problem in a Bayesian framework by means of marginalization. Monte-Carlo simulations show that the new solution provides significantly increased robustness as compared to both the standard PDAF and the probabilistic editing approach. As the new solution has improved theoretical underpinnings, we hope that it can be useful for further research on tracking in the presence of wake clutter.

Aaron Fisher, Florida Atlantic University, USA – Station Keeping of Small Outboard-Powered Boats
     Abstract—Three station keeping controllers have been developed which work to minimize displacement of a small outboardpowered vessel from a desired location. Each of these three controllers has a common initial layer that uses fixed-gain feedback control to calculate the desired heading of the vessel. A second control layer uses a common fixed-gain feedback controller to calculate the net forward thrust, one of two algorithms for controlling engine angle (Fixed-Gain PID or PID with Adaptively Augmented Gains), and one of two algorithms for differential throttle control (Fixed-Gain PID and PID with Adaptive Differential Throttle gains), which work together to eliminate heading error. The three selected controllers are evaluated using a numerical simulation of a 33-foot center console vessel with twin outboards that is subject to wave, wind, and current disturbances. Each controller is tested for its ability to maintain position in the presence of three sets of environmental disturbances. These algorithms were tested with current velocity of 1.5 m/s, significant wave height of 0.5 m, and wind speeds of 2, 5, and 10 m/s. These values were chosen to model conditions a small vessel may experience in the Gulf Stream off of Fort Lauderdale. The Fixed-gain PID controller progressively got worse as wind speeds increased, while the controllers using adaptive methodologies showed consistent performance over all weather conditions and decreased heading error by as much as 20%. Thus, enhanced robustness to environmental changes has been gained by using an adaptive algorithm.

Angelos Mallios, Universitat de Girona, Spain – Probabilistic Sonar Scan Matching SLAM for Underwater Environment
     Abstract—This paper proposes a pose-based algorithm to solve the full Simultaneous Localization And Mapping (SLAM) problem for an Autonomous Underwater Vehicle (AUV), navigating in an unknown and possibly unstructured environment. A probabilistic scan matching technique using range scans gathered from a Mechanical Scanning Imaging Sonar (MSIS) is used together with the robot dead-reckoning displacements. The proposed method utilizes two Extended Kalman Filters (EKFs). The first, estimates the local path traveled by the robot while forming the scan as well as its uncertainty, providing position estimates for correcting the distortions that the vehicle motion produces in the acoustic images. The second is an augmented state EKF that estimates and keeps the registered scans poses. The raw data from the sensors are processed and fused in-line. No priory structural information or initial pose are considered. Also, a method of estimating the uncertainty of the scan matching estimation is provided. The algorithm has been tested on an AUV guided along a 600 m path within a marina environment and is compared against previous work from the authors, showing the viability of the proposed approach.

Francesco Maurelli, Heriot-Watt University, Scotland (UK) – Particle Diversity Reduction for AUV’S Active Localisation
     Abstract—An Autonomous Underwater Vehicle (AUV) needs to demonstrate a number of capabilities, in order to carry on autonomous missions with success. One of the key areas is autonomous localisation, i.e. the capability of the AUV to estimate correctly its position and orientation in the environment. However, most of the proposed approaches are “passive”, with no robot motion control involved. The “active” localization incorporates the control of the robot motion, as a way to improve the robustness of the AUV localisation, finding the best path to follow in order to reduce the uncertainty in the state estimation. Representing the vehicle’s belief of the state with particles, the active localisation module is triggered when there is a clear grouping in the particles and it produces as an output the path to be followed in order to reduce the uncertainty. Both simulation results and tank trials have shown the advantages of using this technique compared to the classical ones.

Ariell Friedman, Australian Centre for Field Robotics, University of Sydney, Australia – Rugosity, Slope and Aspect Derived from Bathymetric Stereo Image 3D Reconstructions
     Abstract—This paper demonstrates how multi-scale measures of rugosity, slope and aspect can be derived from fine-scale bathymetric reconstructions created using geo-referenced stereo imagery collected by an Autonomous Underwater Vehicle (AUV). We briefly describe the 3D triangular meshes generated from the stereo images and then present a detailed overview of how rugosity can be derived by considering the area of triangles within a window and their projection onto the plane of best fit. By obtaining the plane of best fit, slope and aspect can be calculated with very little extra effort. The results are validated on a simulated surface and the effects of mesh resolution and window size are explored. The technique is demonstrated on real data gathered by an AUV on surveys that cover several linear kilometres and consist of thousands of images. The ability to distinguish habitat types based on rugosity and slope are demonstrated through K-means cluster analysis. A human labelled data set is then used to train a SVM classifier that exhibits promising habitat classification potential based on rugosity and slope.

Daniel Steinberg, Australian Centre for Field Robotics, University of Sydney, Australia – Dirichlet Process Mixture Models for Autonomous Habitat Classification
     Abstract—There is a need for truly unsupervised approaches to understanding acquired data in autonomous exploratory missions with minimal, or zero, bandwidth communication. This paper presents results of using a Bayesian non-parametric Dirichlet Process mixture model – the Infinite Gaussian Mixture Model (IGMM) – for the classification of benthic habitats. The IGMM is trained completely autonomously, without being given labeled data, or knowing the number of habitats present. It is able to infer the number of habitats present in the training data, and is also able to infer the presence of habitats in the test data that were not present in the training data. This is a powerful model for entirely autonomous labelling of benthic datasets, and will be used as the basis of completely autonomous approaches to understanding data in the future.

Francois-Xavier Socheleau, Telecom Bretagne, France – A Maximum Entropy Framework for Statistical Modeling of Underwater Acoustic Communication Channels
     François-Xavier Socheleau received the Eng. degree in Electronics from Ecole Supérieure d’Electronique de l’Ouest (ESEO), Angers, France, in 2001. From 2001 to 2004, he was a research engineer at Thales Communications (France) where he worked on non-cooperative communication interception. From 2005 to 2007 he was employed at Navman Wireless (New Zealand/UK) as a R&D engineer. He is currently working toward the Ph.D degree at Telecom Bretagne (France) in collaboration with Thales Underwater Systems. His research interests include underwater acoustic communications, propagation channel modeling, cognitive radio and communication electronic support.
     Abstract—Based on a method of inductive inference known as the principle of maximum entropy, a time-varying underwater acoustic channel model is derived. The resulting model is proved to be consistent so that it only relies on the available knowledge of the environment to model. While requiring only a few parameters (e.g. channel average power and Doppler spread), it is shown through fading statistics and bit error rates measurements that accurate channel impulse responses can be obtained for communication applications. The Matlab code of the proposed model is available at http://perso.telecombretagne.eu/ fxsocheleau/software.

Jo Borchsenius, Auckland University of Technology, New Zealand – Underwater Glider Propulsion Using Chemical Hybrides
     Jo Borchsenius received a BSc. in mechanical engineering from Soer Troendelag University College in Norway spring 2006. He then worked for National Oilwell Varco manufacturing and further developing drilling equipment for the offshore petroleum industry, before he in 2008 pursued and received a BSc. Hons. in material science from the University of Cape Town where he was rewarded the Class Medal finishing on top of his class. He is currently working on a ME at Auckland University of Technology developing a novel buoyancy engine for underwater gliders, which goes well with his lifelong love for the ocean both on and off work. His research interests are in system and product development, especially in overall efficiency from energy source to final output.
     Abstract—A novel buoyancy engine for the propulsion of underwater gliders is presented. The research explores the direct volume expansion of hydrogen gas from the reaction of lithium hydride with seawater. As a result the seawater is expelled from the reaction chamber creating buoyancy and consequently also propulsion. The hydrogen produced can then be used to create electric energy in a fuel cell for use by the vehicle control system and on-board scientific payload.

Divya Parihar, Indian Institute of Technology, Delhi, India – Time Reversal Mirror: Temporal an Spatial Focusing Tool
     Abstract—Time reversal is a technique to focus waves, both temporally and spatially, through an inhomogeneous medium. The incident pressure wave is time reversed and re-transmitted from an array of transducers to focus the pressure on a source or at a point target which may be reflective. This array of sensors is called time reversal mirror (TRM). In this paper, we have studied the spatial and the temporal focusing properties of different TRM array geometries. Two dimensional as well as three dimensional geometries for different configurations and environment have been studied. It has been found that there exists optimal array configuration for both temporal and spatial focusing.

Serge Pons, Freixes, Marine Technology Unit, Centre Mediterrani d’Investigacions Marines/Ambientals, Spain – Video-Image Processing Applied to the Analysis of the Behavior of Deep-Water Lobsters (Nephrops norvegicus)
     Abstract—In this study, we show the results of applying two automated data processing methods to a set of videos previously used to manually monitor the period and the phase of activity rhythms of the deep-water Norway lobster, Nephrops norvegicus, a species of elevated commercial fishery value. Present data are consistent with published findings on Nephrops norvegicus activity rhythms both in the laboratory and the field

Gabrielle Inglis, University of Rhode Island, USA – Constrained Stereo Correspondence for 3D Seafloor Reconstruction
     Abstract—There is a persistent need in the oceanographic community for accurate three dimensional reconstructions of seafloor structures. To meet this need underwater mapping techniques have expanded to include the use of stereo vision and high frequency multibeam sonar for mapping scenes 10’s to 100’s of square meters in size. Both techniques have relative advantages and disadvantages that depend on the task at hand and the desired accuracy. In this paper, we develop a method to constrain the often problematic stereo correspondence search to small sections of the image that correspond to estimated ranges along the epipolar lines calculated from coregistered multibeam sonar microbathymetry. This approach can be applied to both sparse feature-based and dense area-based stereo correspondence techniques. Data were collected on an underwater vehicle survey using a calibrated stereo rig and a multibeam sonar gathering coincident datasets. Overall, the constrained correspondence method shows improvements in the number and reliability of correct matches and allows for reduction in complexity of feature descriptors but it is reliant on the quality of both intrinsic and extrinsic sensor calibration.

Lashika Medagoda, Australian Centre for Field Robotics, University of Sydney, Australia – Water Column Current Profile Aided Localisation for Autonomous Vehicles
     Abstract—Survey class Autonomous Underwater Vehicles (AUVs) rely on Doppler Velocity Logs (DVL) for precise navigation near the seafloor. In cases where the seafloor depth is greater than the DVL bottom lock range, transiting from the surface, where GPS is available, to the seafloor presents a localization problem since both GPS and DVL are unavailable in the midwater column. This paper proposes an alternative approach to navigation in the mid-water column that exploits the fact that current profiles of water columns are stable over time. With reobservation of these currents with the ADCP (Acoustic Doppler Current Profiler) mode of the DVL during descent, along with sensor fusion of other low cost sensors, position error growth can be constrained to near the initial velocity uncertainty of the vehicle at the sea surface during the dive, and following DVL bottom lock, the entire velocity history is constrained to an error similar to the DVL velocity uncertainty. Simulation results show performance with sensor fusion of a low cost IMU and DVL bottom lock at the sea floor can achieve 20 cm per minute (2 σ) position error growth. Results with real data from an Autonomous Benthic Explorer (ABE) dive show that this method is applicable and a promising approach to navigation for untended deepwater autonomous vehicle operations.

Eric Ferguson, University of Sydney, Australia – Precise Sound Source Localisation of Dolphin Biosonar Pulse Transmissions
     Abstract—Dolphins rely on auditory perception for survival and their biological sonars (or biosonars) equip them for life in marine environments. Dolphins probe their habitats using sequences of short underwater sound pulses (or clicks) for echolocation that enable them to navigate and avoid collisions with natural objects in the environment, and to detect and discriminate between prey, predators, and companions. In May 2009, sequences of biosonar click transmissions, which were emitted by Tursiops aduncus dolphins while swimming freely in their natural habitat, were recorded by a linear array of three widely spaced hydrophones located close to the sea floor in Jervis Bay (35° 07' S, 150° 42' E), New South Wales. In this paper, the hydrophone array output data for two sequences are processed for a
7.5 s observation period, where the arrival time differences of the biosonar signals at the hydrophones are measured to within 0.1 μs. The active biosonar of an individual dolphin is observed to operate in two modes – a regular mode, where the time interval between consecutive click transmissions is long (13–59 ms), followed by a burst mode, where there is a rapid succession of pulses with a short time interval (2–9 ms) between buzz signal transmissions. The source position of each click is localized by using the method of passive ranging by wavefront curvature. This nonintrusive acoustic source localisation method requires the differences in the arrival time data of the received pulses to estimate the range of the source from the centre of the array, as well as its bearing angle with respect to the longitudinal axis of the array. During the observation period, a dolphin is detected near the array. Initially, it is at a range of 28 m at the beginning of the regular click phase, and then it closes to a range of 13 m by the end of the buzz phase. Also, there is a rapid source bearing rate change during the buzz phase, with the bearing changing by 9° in 0.7 s. The instantaneous range and bearing of the moving source change continuously and vary by less than 13 cm and 0.07° respectively between interclick transmissions, and 2 cm and 0.06° between consecutive buzz signals. In addition, the arrival times at the hydrophones of click signals from a far dolphin are extracted from the data. For the 17 click transmissions that formed a sequence, the interclick time interval varies from 34 to 58 ms. The passive ranging by wavefront curvature method estimates the range of the far dolphin as 239 ± 1 m with a bearing of 30.05° ± 0.01°. With this source localisation method, the precision of the source bearing estimates is within 0.01°, independent of the source range. The precision of the source range estimates varies from 1 cm for the near dolphin buzz sequence to 1 m for the far dolphin click sequence.

Elena Torrecilia, Marine Technology Unit, Centre Mediterrani d’Investigacions Marine/Ambientals, Spain* – Mapping Marine Phytoplankton Assemblages From a Hyperspectral and Artificial Intelligence Perspective
*Poster presented by Ismael F. Aymerich
     Abstract—The aim of this contribution is to demonstrate the feasibility of different processing techniques to identify phytoplankton assemblages when applied to oceanographic hyperspectral data sets (i.e. above surface measurements and vertical profiles). In order to address this issue and validate the proposed techniques, a simulated framework has been used based on the oceanic radiative transfer model Hydrolight-Ecolight 5.0. The potential offered by an unsupervised hierarchical cluster analysis technique and two Artificial Intelligence algorithms (i.e. Particle Swarm Optimization and Case-Based Reasoning) have been explored. Our results confirm their suitability to map phytoplankton’s distribution from hyperspectral information given a variety of hypothetical oceanic environments.

Michael Stanway, MIT/WHOI, USA – Water Profile Navigation with an Acoustic Doppler Current Profiler
     M. J. Stanway is a Doctoral Candidate in the Massachusetts Institute of Technology / Woods Hole Oceanographic Institution Joint Program in Oceanography / Applied Ocean Science and Engineering. He works on autonomous underwater vehicles with Dr. Dana Yoerger in the Deep Submergence Laboratory at Woods Hole Oceanographic Institution. His current research focuses on underwater navigation, including techniques for descent/ascent, fusing delayed measurements, and automatic sensor alignment. He received his S. M. and S. B. degrees in Ocean Engineering from the Massachusetts Institute of Technology in 2008 and 2006, respectively.
     Abstract—A novel navigation method is introduced using water current profiles measured by an Acoustic Doppler Current Profiler (ADCP) mounted on a moving vehicle. These current profiles are combined with measurements of vehicle attitude and depth to simultaneously estimate the local current and the vehicle velocity. This velocity estimate can be integrated directly to give a position estimate, or it can be fused with measurements from other navigation sensors, such as an Inertial Navigation System (INS), Long Baseline (LBL) or Ultra-Short Baseline (USBL) acoustic tracking system. The method allows an underwater vehicle to maintain an estimate of its global position throughout all phases of its mission, including descent and ascent.

Natalia Hurtos, Universitat de Girona, Spain – Calibration of Optical Camera Coupled to Acoustic Multibeam for Underwater 3D Scene Reconstruction
     Abstract—Combination of optical and acoustic sensors to compensate the strengths and weaknesses of each sensor modality is a topic of increasing interest in applications involving autonomous underwater vehicles (AUV). In this work, an opti-acoustic system composed by a single camera and a multibeam sonar is proposed, providing a simulation environment to validate its potential use in 3D reconstruction. Since extrinsic calibration is a prerequisite for this kind of feature-level sensor fusion, an effective approach to address the calibration problem between a multibeam and a camera is presented.

M. Azizur Rahman, University of Ryukyus, Japan – The Role of Carbonic Anhydrase Enzyne in the Biocalcification Process of Coral and its Resilience to Global Climate Change
     Abstract—Here we report that the organic substances that participate in calcification in coral skeletons contain a carbonic anhydrase (CA) enzyme which is a biological catalyst responsible for the interconversion of CO2 and bicarbonate. The effect of CA on the hydration of CO2, and its precipitation in the form of calcium carbonate, was studied. The precipitation of calcium carbonate was promoted in the presence of the enzyme. However, we find that the CA acts as “keys” to control internal physiological condition of the body of corals via calcification and to enable a response to external environmental change. Therefore, the CA enzyme is considered to be key biomolecule to understand calcification mechanisms and global climate change.

Bryan McGilvray, University of Rhode Island, USA – Control System Performance and Efficiency for a Mid-Depth Lagrangian Profiling Float
     Abstract—This paper presents the development of a new mid–depth Lagrangian profiling float with a primary emphasis on the control system performance and efficiency. While deep water floats have demonstrated much success in open ocean environments, many are not suited for the additional challenges associated with coastal regions. To study these regions, which are often subject to varying bathymetry within the operating range and higher variations in water density, a more advanced system is required. This new design utilizes pressure and altitude feedback to drive a high volume auto-ballasting system (ABS). The main operating modes of this float include step inputs to park and drift at constant depths, profiling inputs with adjustable rates and adaptable limits, and constant altitude bottom tracking. To handle these tasks, a state–space feedback control system, which uses feedback linearization to account for the nonlinear drag force acting on the moving float, was designed and simulated. Additionally, the development of the control system was coupled with empirical motor efficiency data to study the tradeoffs between efficiency and performance.
     The judging team attended the oral presentations and then reviewed each poster with the student in attendance. The judges turned in their rating sheets and Dr. Williams and Mr. Miller reviewed the results and selected the winners as follows:

1st Place: Ariell Friedman
2nd Place: Francois-Xavier Socheleau and Anuj Sehgal
3rd Place: Gabrielle Inglis, Lashika Medagoda, and M. Azizur Rahman

     Each student received a round of applause as they received their award. The quality of the poster presentations was outstanding and the research work covered a wide spectrum. All of the students expressed their appreciation for being invited to the Conference and made good use of their time to attend sessions and view the exhibits as well as being at their posters. Once again the Student Poster Program had achieved its objective of showing students what the field of Oceanic Engineering was all about.