Autonomous Underwater Vehicle

This dissertation addresses attitude control and inertial navigation of autonomous underwater vehicles (AUVs). We present theoretical justification for using simplified models, derive system identification algorithms, and verify our results through extensive field trials. Although this research focuses on small AUVs with limited instrumentation, the results are useful for underwater vehicles of any size. standing team. I wish everybody good luck in their future endeavors.

We present a complete, video-based 3d documentation process for the submerged remains of Neolithic pile dwellings at the UNESCO World Heritage Site "See am Mondsee "in Austria. We discuss good practice routines and solutions, such as cable management, supporting the Unmanned Underwater Vehicle (UUV) when strong currents are prevalent, and documentation/record keeping. The recorded site is a Neolithic lake village dating to the 4th millenium BC. Based on initial reconstruction results, we improved the image matching process of our Structure from Motion (SfM) pipeline (built around the free end-user application VisualSFM), by replacing its default feature detector (SiftGPU) with our own implementation of adaptive feature detection. The campaign was accompanied by a German television film crew. Their documentary was shown on the German public television (ARD) broadcast "W wie Wissen" .

This paper is to present the design, development and prototyping of an electrically actuated thruster as a direct drive propulsion system based on a 3-phase permanent magnet brushless machine for an autonomous underwater vehicle. The non-linear design and analysis of the permanent magnet brushless motor are entirely performed in 2-d finite element method. The motor is then coupled directly to a 6-inch mechanical propeller, thus providing a peak thrust of 25N for the AUV's manoeuvre. Critical key performances are accounted for in the analysis such as maximum speed capability, maximum output torque and efficiency at 48V dc battery supply. Other electromagnetic considerations such as cogging torque, slot numbers and pole numbers are also addressed. Hall-effect sensors are embedded inside the motor structure in order for the motor to successfully operate in bldc mode. The optimized motor design has been prototyped and tested to work as direct drive propulsion system. The results obtained from the experiment conducted in laboratory in an open water testbed show satisfactory performance with a rated 15N continual bollard thrust at 1200rpm motor speed.

It has recently been shown that inner shelf waters of NE Monterey Bay, California function as an ''extreme bloom incubator'', frequently developing dense ''red tide'' blooms that can rapidly spread. Located within the California Current upwelling system, this open bay is strongly influenced by oceanographic dynamics resulting from cycles of upwelling favorable winds and their relaxation and/or reversal. Different wind forcing causes influx of different water types that originate outside the bay: cold nutrient-rich waters during upwelling and warm nutrient-poor waters during relaxation. In this study, we examine how the bay's bloom incubation area can interact with highly variable circulation to cause red tide spreading, dispersal and retention. This examination of processes is supported by satellite, airborne and in situ observations of a major dinoflagellate bloom during August and September of 2004. Remote sensing of high spatial, temporal and spectral resolution shows that the bloom originated in the NE bay, where it was highly concentrated in a narrow band along a thermal front. Upwelling circulation rapidly spread part of the bloom, mixing cool waters of an upwelling filament with warm bloom source waters as they spread. Vertical migration of the dinoflagellate populations was mapped by autonomous underwater vehicle surveys through the spreading bloom. Following bloom expansion, a two-day wind reversal forced intrusion of warm offshore waters that dispersed much of the bloom. Upwelling winds then resumed, and the bloom was further dispersed by an influx of cold water. Throughout these oceanographic responses to changing winds, an intense bloom persisted in sheltered waters of the NE bay, where extreme blooms are most frequent and intense. Microscopic examination of surface phytoplankton samples from the central bay showed that spreading of the bloom from the NE bay and mixing with regional water masses resulted in significantly increased abundance of dinoflagellates and decreased abundance of diatoms. Similar dinoflagellate bloom incubation sites are indicated in other areas of the California Current system and other coastal upwelling systems. Through frequent bloom development and along-coast transports, relatively small incubation sites may significantly influence larger regions of the coastal marine ecosystems in which they reside.

This article provides a general overview of the autonomous underwater vehicle (AUV) research thrusts being pursued within the Perceptual Robotics Laboratory (PeRL) at the University of Michigan. Founded in 2007, PeRL's research centers on improving AUV autonomy via algorithmic advancements in environmentally-based perceptual feedback for real-time mapping, navigation, and control. Our three major research areas are: (1) real-time visual simultaneous localization and mapping (SLAM); (2) cooperative multi-vehicle navigation; and (3) perception-driven control. Pursuant to these research objectives PeRL has developed a new multi-AUV SLAM testbed based upon a modified Ocean-Server

The early results in the development of a platform for experimental underwater robotics research are presented in this work. This platform consists of an Unmanned Underwater Vehicle (UUV) and a Mission Monitoring/Control System (MMCS) unit to teleoperate and to supervise the underwater vehicle. Following the initial phases of a product design methodology, a conceptual model for the platform was obtained. This model and the design process are analyzed here. The first results in the implementation of a prototype are also presented.

A thermodynamic model is developed for a novel underwater propulsion system called a hybrid aluminum combustor (HAC) that is based on the exothermic reaction of aluminum powder with sea water. The Rankine cycle-based propulsion system’s components are created and linked together using a system modeling tool called Numerical Propulsion System Simulation (NPSS). The results of the system simulation show that replacing battery- based power systems in unmanned underwater vehicles (UUVs) with HAC-based systems could increase range and endurance by factors of 2 to 5. A rudimentary sensitivity analysis indicates that overall system efficiency is maximized by adjusting the ratio of water mass flow to fuel mass flow so as to control the temperature and quantity of steam. The results also indicate that increasing the amount of combustion byproduct, hydrogen, improves the performance of the turbine. However, the thermodynamic costs of compressing the hydrogen can be high. More work is required to assess the impacts of frictional, thermal, hydrogen compression, and component integration losses on power output and efficiency.