Teledyne Webb Research (TWR) provides here an overview of the latest Slocum G2 features including the hybrid thruster, increased buoyancy pump displacement, new sensor suites, and an update on the energy harvesting Slocum Thermal E Twin. Three main mission objectives will be reviewed: polar regions, acoustic data telemetry, and long duration transects approximating the course of the Challenger expedition of 1872-76.More
SAILING the seven seas is old hat. The latest trick is to glide them. Sea gliders are small unmanned vessels which are now cruising the briny by the hundred. They use a minuscule amount of power, so they can stay out for months. And, being submarines, they are rarely troubled by the vicissitudes of weather at the surface. Their only known enemies are sharks (several have come back covered in tooth marks) and fishing nets.
Sea gliders are propelled by buoyancy engines. These are devices that pump oil in and out of an external bladder which, because it deflates when it is empty, means that the craft’s density changes as well. This causes the glider to ascend or sink accordingly, but because it has wings some of that vertical force is translated into horizontal movement. Such movement is slow (the top speed of most gliders is about half a knot), but the process is extremely efficient.
That means gliders can be sent on long missions. In 2009, for example, a glider called Scarlet Knight, operated by Rutgers University, in New Jersey, crossed the Atlantic on a single battery charge, though it took seven months to do so.
Since that crossing, gliders have been deployed on many previously unthinkable missions. In 2010 teams from the American navy, the Scripps Institution of Oceanography and iRobot, a robot-maker based in Bedford, Massachusetts, used them to track the underwater effects of the Deepwater Horizon oil spill in the Gulf of Mexico. That same year a glider owned by Oregon State University watched an underwater volcano erupting in the Lau basin near Tonga. In 2011 a glider made by another firm, Teledyne Webb of East Falmouth, also in Massachusetts, tracked seaborne radiation leaked from the tsunami-damaged reactors in Fukushima, Japan. And the University of Newfoundland is planning to use gliders equipped with sonar to inspect icebergs, to work out whether they are a threat to underwater cables and other seabed infrastructure.More
Exocetus Development, LLC of Anchorage Alaska has recently purchased the assets, IP, and manufacturing technology for the ANT Littoral Glider [now called the Coastal Glider] developed with ONR funding during the past 6 years. The glider technology developed under this program is now being modified to be more readily deployed in near coastal scientific applications. The glider is capable of self-ballasting from essentially fresh to full ocean water, and has a variable speed capability to allow it to handle near shore currents up to 2 knots. The glider is currently being modified to include a dedicated science computer and improved communications and survivability. This paper describes the prior and current development of this vehicle, describes the vehicle’s capabilities and specifications, discusses initial applications, and describes plans for future development. Additionally, some of the testing conducted during the past two years by GA Tech, NPGS, NUWCI-Newport, and KORDI in Korea is presented.More
The mission: determining the utility of AUVs for collecting data on the rapidly receding Helheim Glacier.
They needed to determine  how an underwater vehicle could reach the glacier,  find a sonar system that would work with both glacial and arctic ice, and  understand the operational challenges inherent in such an isolated environment. The team also needed to assess operational logistics for future AUV operations through the deployment of glider AUVs for oceanography and an assessment is also needed for a multi-narrow beam sonar for iceberg profiling and for the creation of future obstacle avoidance algorithms.More
Currently, buoyancy driven underwater gliders are deployed globally to gather oceanographic data from across the world’s oceans. This thesis examines the utility of underwater gliders within the context of providing additional U.S. Navy capabilities. An extensive survey of available underwater gliders was undertaken and the resultant survey pool of ten gliders down selected to five gliders of fixed wing configuration. A comprehensive architectural analysis was then conducted of seven key architectural attributes of the five selected gliders. The architectural analysis compared various implementations of the key architectural attributes relative to desirable traits and capabilities for a notional U.S. Navy glider. Following the architectural analysis a proposed architecture for a U.S. Navy underwater glider was developed which includes a compendium of ‘best’ features gleaned from the architectural analysis. Drivers and rationale for selection of specific key architectural attributes and features are also provided. Additionally, a comparison of constraints and capabilities of underwater gliders is provided. Finally, a comparison of the current and proposed capabilities of underwater gliders versus other Autonomous Undersea Vehicles, specifically Unmanned Undersea Vehicles, is proffered.More
When VaCAS researchers were unable to find an underwater glider that could test their different designs and control algorithms, they decided to build one. Now working on their second version of the testbed, the researchers, led by aerospace and ocean engineering faculty members Craig Woolsey and Leigh McCue, are developing an underwater glider that is very different from its peers.
A 360 ROLL CAPABILITY
The Virginia Tech testbed glider shares the general design elements and capabilities of other underwater gliders; however, it has a creative buoyancy actuation system and it can roll over. With this rollover capability, researchers can test more efficient turning schemes and control algorithms.
Most underwater gliders use symmetric airfoils to achieve high efficiency whether sinking or rising. The ability to roll over means that this glider does not need symmetric airfoils, and can therefore use more efficient, curved (“cambered”) airfoils — like the ones used for gliders in the air.More
In a wide ranging discussion with General Heinz, former PEO of the F-35 program and now head of Maritime Systems in I Robot (and working for the former head of NAVAIR, now the COO of I Robot), the current state of Maritime Robotic systems was discussed as well as their prospects.More
Architecture: A significant change is that instead of providing shallow and deep gliders, the G2 is pressure tolerant to 1000 meters depth operation and, building on the modular concept, can be outfitted with interchangeable front pump sections that are optimized for the operational depths. Pump combinations include 30, 100, 200, 350, and 1000 meters. Carrying the additional structure to handle a greater pressure tolerance and still have acceptable payload performance in the shallow water regime is made possible by utilizing our patented composite hulls sections that are significantly lighter than aluminum and additionally are tuned to match the compressibility of water – saving buoyancy drive energy during ascent and descent.More
The development of a magnetometry system for an underwater glider is detailed in this paper. The system is designed for low noise, low sampling rates and high accuracy measurements. The integration progress into a 200 m Slocum Electric glider is presented in addition to an evaluation of the electrical and system noise levels. A calibration algorithm is evaluated for correcting sensor errors as well as hard and soft magnetic effects due to the glider.More
Underwater Gliders have found broad applications in ocean sampling. In this paper, the nonlinear dynamic model of the glider developed by the Shenyang Institute of Automation, Chinese Academy of Sciences, is established. Based on this model, we solve for the parameters that characterize steady state spiraling motions of the glider. A set of nonlinear equations are simplified so that a recursive algorithm can be used to find the solutions.More
We have been involved in collaborative research that uses Slocum gliders to study Harmful Algal Blooms in the Southern California Bight region. The Southern California Bight (SCB) region is home to the ports of Los Angeles and Long Beach which collectively handle approximately 40% of all US container traffic. This large shipping traffic along with a significant presence of smaller crafts in the ocean necessitates careful path-planning to avoid risking collisions with ships while the vehicle is at the surface. All container ships as well as commercial passenger craft are mandated to transmit their locations to VTS terminals nearby to indicate their location, speed and so on using the Automatic Information System (AIS). We have analyzed AIS information from 2009 and 2010 for the SCB (see Figure 1), and use this processed data along with well-established path-planning algorithms to plan missions for the gliders which reduce risk while going between way-points chosen for the scientific mission.
PETREL, a winged hybrid-driven underwater glider is a novel and practical marine survey platform which combines the features of legacy underwater glider and conventional AUV (autonomous underwater vehicle). It can be treated as a multi-rigid-body system with a floating base and a particular hydrodynamic profile. In this paper, theorems on linear and angular momentum are used to establish the dynamic equations of motion of each rigid body and the effect of translational and rotational motion of internal masses on the attitude control are taken into consideration. In addition, due to the unique external shape with fixed wings and deflectable rudders and the dual-drive operation in thrust and glide modes, the approaches of building dynamic model of conventional AUV and hydrodynamic model of submarine are introduced, and the tailored dynamic equations of the hybrid glider are formulated. Moreover, the behaviors of motion in glide and thrust operation are analyzed based on the simulation and the feasibility of the dynamic model is validated by data from lake field trials.
Key words: hybrid-driven; underwater glider; autonomous underwater vehicle; dynamic modeling; momentum theorem
A newer class of coating that is specifically formulated for undersea instruments (optical or acoustic, for example) and specialized platforms such as gliders has recently emerged and was identified by the Rutgers engineering group as a good candidate for the Scarlet Knight. This coating, ClearSignalTM, is a clear, nontoxic, rubber-like coating that resists biofouling because of the nonstick properties of the material itself. The product is a permanent coating that is designed to last for the life of the platform or instrument it is protecting.
The ClearSignal biofouling control system is the product of a joint development effort by Severn Marine Technologies LLC (SMT) and Mercer Island, Washington-based Mid- Mountain Materials Inc. (MMM). The companies originally developed ClearSignal to coat instruments used in the offshore seismic exploration industry. The product was recently reformulated to accommodate the larger oceanographic research community.More
Why current profiling from gliders?
There are really good reasons for making current velocity measurements on a glider. Simply using profiles of current velocity structure and shear as a reference to interpret contour plots of other physical variables is reason enough for many researchers. Measuring higher velocity in one location compared to another could provide evidence of upwelling. Observing variation in the velocity shear at different locations can provide insight to the formation and dissipation of phytoplankton thin layers. Or simply use the acoustic backscatter to map and quantify zooplankton in an effort to understand zooplankton in a effort to understand zooplankton distribution, dynamics, and relationship to whale or fish feeding.
A propulsion module is presented for augmenting the performance of ocean gliders. The proposed module implements a folding propeller and magnetic coupling to allow for intermittent use and minimal power requirements at low levels of thrust. To characterize the propulsion module bollard and open water thrust tests are presented and the relative benefit of the use of a folding propeller over a fixed propeller is shown.More
Prediction of the substantial biologically mediated carbon flows in a rapidly changing and acidifying ocean requires model simulations informed by observations of key carbon cycle processes on the appropriate spatial and temporal scales. From 2000 to 2004, the National Oceanographic Partnership Program (NOPP) supported the development of the first low-cost, fully autonomous ocean profiling Carbon Explorers, which demonstrated that year-round, real-time observations of particulate organic carbon (POC) concentration and sedimentation could be achieved in the world’s ocean. NOPP also initiated the development of a particulate inorganic carbon (PIC) sensor suitable for operational deployment across all oceanographic platforms. As a result, PIC profile characterization that once required shipboard sample collection and shipboard or shore-based laboratory analysis is now possible to full ocean depth in real time using a 0.2-W sensor operating at 24 Hz. NOPP developments further spawned US Department of Energy support to develop the Carbon Flux Explorer, a free vehicle capable of following hourly variations of PIC and POC sedimentation from the near surface to kilometer depths for seasons to years and capable of relaying contemporaneous observations via satellite. We have demonstrated the feasibility of real-time, low-cost carbon observations that are of fundamental value to carbon prediction and that, when further developed, will lead to a fully enhanced global carbon observatory capable of real-time assessment of the ocean carbon sink, a needed constraint for assessment of carbon management
policies on a global scale.
Autonomous Underwater Gliders (AUGs) are becoming the tool of choice for oceanographers to collect in-situ data on the world’s oceans. Since the summer of 2006, the National Research Council-Institute for Ocean Technology (NRC-IOT) and Memorial University (MUN) have been exploring the potential for AUGs to gather oceanographic
information with application to the Newfoundland Shelf. Our group has now collected over a month’s worth of deployment data, and has flown over 700 km with AUGs. Preliminary work has involved testing these vehicles in our local environment and also the integration of new sensors into the platform.
Over the past few decades, a range of strategies and techniques has been used to monitor the sea. More recently, the role of monitoring has been expanded to include the use of autonomous underwater vehicles to perform ocean surveys. With these vehicles it is now possible for the scientist to make complex studies on topics such as the effect of metals, pesticides and nutrients on fish abundance, reproductive success and ability to feed, or on contaminants such as chemicals or biological toxins that are transported in particulate form and become incorporated into living organisms (plankton, bivalves, fishes) or become deposited in bottom sediments. The scientist or environmentalist may desire to detect hazardous substances in the ocean such as chemicals from an underwater vent or toxic algae such as red tide. Additionally, the military’s detection of mines, biological, chemical or radioactive threats are also very important in the monitoring of the seas.
These considerations explain today’s development of new types of autonomous underwater vehicles with integrated sampling equipment that is able to perform a wide-range of fully automated monitoring surveys over extended periods of time. These vehicles survey and monitor the sea environment in a cost-effective manner combining survey capabilities, simultaneous water sampling and environmental data gathering capacities. Included in these types are autonomous underwater gliders that have the ability to glide for long distances and are in some cases able to travel under power. There are currently four classes of underwater gliders: 1) those that use mechanical or electrical means of changing their buoyancy (i.e., drop weights, or electrical power from batteries), 2) those that use the thermal gradient of the ocean to harness the energy to change the vehicle’s buoyancy, 3) those that are able to use other means of power such as ocean wave energy, and 4) hybrid vehicles that use standard propulsion systems and glider systems.More
As tradition now has it, the first blog entry is our dedication. Today we dedicate Rutgers Glider Mission #138, our second mission under the I-COOL banner, to Doug Webb, the inventor of the Slocum autonomous underwater glider.More
Rutgers University Coastal Ocean Observation Lab (RU-COOL) and Webb Research Corporation (WRC) continue to apply the autonomous underwater Slocum gliders in field operations spanning the globe. Our goal is to share the operational experience that we have had with this class of vehicle in the past years and to show the unique data sets acquired.More
The Autonomous Ocean Sampling Network-II (AOSN-II) and Adaptive Sampling and Prediction (ASAP) projects aim to develop a sustainable, portable, adaptive ocean observing and prediction system for use in coastal environments. These projects employ, among other observation platforms, autonomous underwater vehicles that carry sensors to measure physical and biological signals in the ocean. The measurements from all sensing platforms are assimilated in real-time into advanced ocean models. The objective is to coordinate the mobile assets in order to collect data of highest possible utility. Critical to this effort are reliable, efficient and adaptive control strategies to enable the mobile sensor platforms to collect data autonomously. In this paper, we summarize feedback control strategies that enable us to gather useful information over a wide spectrum of spatial and temporal scales. First, we design formation control strategies useful for sampling small spatial scale processes (less than 5 km). In this framework, the feedback control laws maintain a desired formation of vehicles and allow the group to locate interesting features in the ocean. Some of these control strategies were implemented on a group of underwater gliders in Monterey Bay in August 2003, as part of the AOSN-II project. Second, we direct mobile sensor networks to provide synoptic coverage to investigate larger scales (5-100 km). Coordinated vehicle trajectories are designed according to the spatial and temporal variability in the field in order to keep sensor measurements appropriately distributed in space and time.More
Underwater gliders are autonomous vehicles that profile vertically by controlling buoyancy and move horizontally on wings. Gliders are reviewed, from their conception by Henry Stommel as an extension of autonomous profiling floats, through their development in three models, and including their first deployments singly and in numbers. The basics of glider function are discussed as implemented by University of Washington in Seaglider, Scripps Institution of Oceanography in Spray, and Webb Research in Slocum. Gliders sample in the archetypical modes of sections and of “virtual moorings.” Preliminary results are presented from a recent demonstration project that used a network of gliders off Monterey. A wide range of sensors has already been deployed on gliders, with many under current development, and an even wider range of future possibilities. Glider networks appear to be one of the best approaches to achieving subsurface spatial resolution necessary for ocean research.
Autonomous underwater vehicles, and in particular autonomous underwater gliders, represent a rapidly maturing technology with a large cost-saving potential over current ocean sampling technologies for sustained (month at a time) real-time measurements. We give an overview of the main building blocks of an underwater glider system for propulsion, control, communication and sensing. A typical glider operation, consisting of deployment, planning, monitoring and recovery are described using the 2003 AOSN-II field experiment in Monterey Bay, California. We briefly describe the recent developments at NRC-IOT, in particular, the development of a laboratory-scale glider for dynamics and control research and the concept of a regional ocean observation system using underwater gliders.More
Seagliders are small, reusable autonomous underwater vehicles designed to glide from the ocean surface to a programmed depth and back while measuring temperature, salinity, depth-averaged current, and other quantities along a sawtooth trajectory through the water. Their low hydrodynamic drag and wide pitch control range allows glide slopes in the range 0.2 to 3. They are designed for missions in range of several thousand kilometers and durations of many months. Seagliders are commanded remotely and report their measurements in near real time via wireless telemetry. The development and operation of Seagliders and the results of field trials in Puget Sound are reported.More
It is difficult to realize that twenty-five years have passed since I first came to the Slocum Mission Control Center on Nonamesset Island, one of the Elizabeth Islands, in 1996. I was a post-doc in physical oceanography, and the Department of the Environment had just acquired the island from the descendants of a sea captain prominent in the China trade of the early nineteenth century. The government acquired Nonamesset to establish the World Ocean Observing System [WOOS], a facility capable of monitoring the global ocean, using a fleet of small neutrally-buoyant floats called Slocums that draw their power from the temperature stratification of the ocean. Nonamesset Island was chosen partly because it is isolated from the mainland of Cape Cod, but mostly because it is close to the Woods Hole Oceanographic Institution, the Marine Biological Laboratory. and a thriving scientific community.More