Opening session

Manuel Pinto de Abreu
Secretary of State for Maritime Affairs
Portugal



Keynotes

1 - Nonlinear observers for integration of position and IMU measurements
The navigation system is one of the key components when designing modern guidance and control systems. From a historical point of view, navigation is the science of directing a craft bydetermining its position, course, and distance traveled. It is derived from the Latin /navis/, ship , and /agere/, to drive .In some cases velocity and acceleration are determined as well. The software tool for accurate integration of the inertial measurements (accelerometers and gyros) with position measurements is the extended Kalman filter (EKF) algorithm, which dates back to the 1960s. Morerecently, nonlinear observer theory has shown to be an alternative to the EKF algorithm. The inertial navigation systems (INS) principle exploits that acceleration and gyro measurements can be integrated to produce estimates of position, velocity and attitude (PVA). Drift due to sensor bias and measurement noise is corrected by combing the INS with a global navigation satellite system (GNSS) for surface applications or a hydro-acoustic positioning reference (HPR) system for underwater applications. The resulting system forms a feedback connection, which can be analyzed using nonlinear observer theory. This is a nontrivial problem since the system is highly nonlinear and in particular the topological restrictions of the attitude estimation problem on SO(3) makes it difficult to prove global stability. Practical solutions, such as the EKF algorithm, are frequently used for sensor integration. However, this method does not guarantee global exponential stability (GES). In fact, only local results can be proven due to linearization. In addition, the Riccati equations of the SO(3) attitude estimation problem will result in singular points. Nonlinear observers for integration of referencesystems and inertial navigation systems (INS) are a new field of research which seeks to overcome the limitations of the EKF by addressing the topological restrictions on SO(3) using nonlinear theory. These algorithms are computational effective and they can run on relatively small embedded computers with limited clock frequency and power consumption. Today navigation systems are used by marine craft, aircraft, spacecraft, automotive systems, mobile robots, unmanned vehicles and the software developed from these applications have the potential to be used in consumer electronics such as game consoles, remotes, mobile phones and toys. This motivates research on nonlinear observers for effective integration of low-cost micro-electromechanical system (MEMS) gyros, accelerometers and magnetometers aided by position reference systems. The stability results of the nonlinear observers are verified experimentally by considering unmanned aerial vehicles and underwater vehicles.
Thor Fossen
Norwegian University of Science and Technology
Trondheim
Norway

2 - Robotic Cities: on Oceans Opportunities and Challenges
João Fonseca Ribeiro
The Task Group for Maritime Affairs (EMAM)
Portugal

3 - Autonomous Detection and Targeted Sampling of Oceanographic Features by AUVs
In this talk, we will present novel methods of using AUVs for studying oceanographic features that carry significant impact on ocean ecology. For example, in a coastal upwelling system, zooplankton often aggregates at the front between stratified water and upwelling water. We have developed a set of AUV algorithms for autonomous detection of and targeted sampling in oceanographic features such as phytoplankton thin layers and intermediate nepheloid layers, upwelling fronts, and thermocline. These algorithms have been successfully applied on MBARI's Dorado and Tethys AUVs in a series of field experiments. During the April and June 2011 CANON (Controlled, Agile, and Novel Observing Network) Experiments in Monterey Bay, California, the novel detection and targeted sampling capabilities permitted the AUVs to autonomously classify the three distinct water types (stratified water, upwelling water, and the front in between), accurately locate and track the narrow front, and conduct "surgical sampling" of the complex marine ecosystem. There is an ongoing effort of incorporating the third generation Environmental Sample Processor (ESP) into the Tethys long-range AUV. The combination of an AUV-borne ESP and the AUV's capability of autonomously detecting ocean features provides an exciting prospect of conducting molecular biology analysis on targeted water samples in situ.
Yanwu Zhang
Monterey Bay Aquarium Research Institute
Monterey
USA

4 - Cooperative Navigation and Control: Marine Vehicles and Humans in the Loop
This talk addresses the general topic of cooperative navigation and motion control of marine vehicles, both from a theoretical and a practical standpoint. The presentation is rooted in practical developments and experiments. Examples of scientific mission scenarios with autonomous surface vehicles (ASVs) and autonomous underwater vehicles (AUVs), acting alone or in cooperation, set the stage for the main contents of the presentation. From a theoretical standpoint, special attention is given to a number of challenging problems that include: i) cooperative motion control of fleets of autonomous vehicles, ii) optimal sensor placement for multiple underwater vehicle localization with acoustic range measurements, and ii) cooperative vehicle navigation using geophysical and single-beacon measurements. The efficacy of some of the systems developed has been shown during real tests at sea. Recent results on cooperative motion control with applications to the development of devices for robot-assisted diving operations are also described. The results are illustrated with videos from actual field tests with multiple marine robots and a human diver in the loop. The core material presented in the talk was obtained in the scope of the EC GREX and CO3AUVs projects (http://www.grex-project.eu) and (http://www.co3-auvs.org)
António Pascoal
Institute for Systems and Robotics - Instituto Superior Técnico
Lisbon
Portugal

5 - Challenges and limitations of high-resolution sea-floor optical mapping using UUVs
Robotics has greatly advanced in the last few years as a tool for environmental monitoring and seafloor characterization. Seafloor imagery is routinely acquired during near-bottom mapping surveys conducted by Unmanned Underwater Vehicles (UUVs). Deep-sea hydrothermal fields or shallow-water coral reef communities are, for instance, two scenarios that have long been the target of such studies. Imagery is useful to characterize the nature and distribution of geological features and biological communities, extract ecological indicators, and to provide a permanent visual record of the seafloor condition. However, imaging studies often yield large numbers of images (several tens of thousands, especially in deep-sea cruises) that are frequently underutilized largely because of the difficulties inherent in processing and visualizing large data sets. Moreover, light suffers from a rapid and nonlinear attenuation underwater that affects the acquired images, which forces AUVs to navigate close to the seafloor, thus increasing the risk of the survey mission.
In this talk we will present ongoing work at the University of Girona towards development and application of vision-based seafloor survey methodologies, including large area 2D mosaicing (>1sqkm), monocular-based 3D mosaicing, and stereo seafloor modeling. The developed tools set a first step towards detecting and documenting the temporal variations associated with the active processes operating at these sites.
Rafael Garcia
University of Girona
Girona
Spain

6 - The Role of Artificial Intelligence based Inference for AUV Sampling, Command and Control
Persistent under-sampling of complex coastal ocean processes has resulted in calls for new methods to approach the sampling problem. Autonomous Underwater Vehicles (AUVs) have been used over the last few years to observe dynamic events such as blooms, anoxic zones and ocean fronts. However they had till recently, been stymied with the use of simple reactive approaches which depended on a priori plans which prevented any substantiative adaptation of mission structure to deal with opportunistic science and other unanticipated events. Further formulation of reactive plans have resulted in non-systematic and a 'band-aid' approach to software engineering which is discombobulated with systematic software architecture. Such ad-hoc approaches have resulted in software bloat not only boxing future developers from contributing to the code-base, but stymying efforts from anyone other than the original developer from doing sustaining engineering.
We motivate the use of Artificial Intelligence (AI) based Planning and Execution using /generative/ planning techniques in-situ for such robots and highlight the range and diversity of applications which have been impacted to enable novel observations. The talk will explore collaborative scientific missions used within a very inter-disciplinary environment at MBARI and highlight future challenges for this domain in AI Planning, Data Mining, Mixed-Initiative distributed control and Machine Learning.
Kanna Rajan
Monterey Bay Aquarium Research Institute
Monterey
USA

7 - Some algorithms of AUV positioning based on one moving beacon
The report is devoted to designing of algorithms for AUV mobile navigation system operation. The navigation system includes AUV onboard reckoning system and acoustic positioning system with long base line that uses single moving beacon. The approach is described where at first the initial AUV position and sound velocity in water are estimated and than AUV position is calculated on the base of the Kalman filtering. The algorithm for mobile beacon trajectory creation is discussed that allows minimizing the AUV positioning error. Some modeling results of proposed approach operation are supplemented.
Alexander Scherbatyuk
Institute for Marine Technology Problems
Vladivostok
Russia