Tactical Decision Aid Research Articles

An Embedded Tactical Decision Aid Framework for Environmentally Adaptive Autonomous Underwater Vehicle Communication and Navigation

Motivated by a changing acoustic environment in the Arctic Beaufort Sea, in this article, we present a tactical decision aid framework for a human decision-maker collaborating with an autonomous underwater vehicle (AUV) to integrate the vertical sound-speed profile for underwater navigation and communication. In a predeployment phase, using modeled and real oceanographic data, we load basis function representations of the sound-speed perturbations onto one or more AUVs on deck, where a handful of weights can estimate a sound-speed profile. During deployment, these weights are updated on an AUV through a digital acoustic message to improve navigation and reciprocal communication throughout the duration of an under-ice mission. Field work applying this framework in the Beaufort Sea is presented, highlighting key decisions regarding predeployment oceanographic data assimilation, CTD cast collection, and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> weight choice. Selected examples evaluate the framework’s ability to adapt to a depth-limited CTD cast and the appearance of an anomalous microlens feature in the profile. We show that the framework effectively balances the need to adapt in a changing acoustic environment in real time while maintaining operator trust in an AUV’s embedded intelligence.

Implementation of Tactical Decision Aids Based on Event Knowledge Graph

This paper proposes a new tactical decision aids method based on event knowledge graph (EventKG). In the warfare domain, EventKG can be constructed through event types design, event network construction and transition probability computation between events. Initially, four event classes are introduced in accordance with the OODA loop, and eighteen subclasses are further decomposed. With the aids of a common event template, all the events taking place in the battle field can be described. Event networks are built by adopting the hierarchical task network (HTN) and described through Bayesian network, to exhibit various relations between battle events. Transition probability, namely the occurrence probability of next possible event, is computed by using the prior probability and conditional probability of event occurring. On the basis of structured EventKG, entity knowledge graph (EKG) and entity relation knowledge graph (ERKG), tactical decision aid instructions can be generated by combining with the battlefield situation information.

Forty-year review of developments in underwater acoustic modeling

This is the sixth paper in a series of reviews presented at eight-year intervals starting in 1979 [J. Acoust. Soc. Am. 65, S42 (1979); 82, S102 (1987); 97, 3312 (1995); 114, 2430 (2003); 129, 2631 (2011)]. All surveys covered basic acoustic models and sonar performance models. Basic acoustic models included 143 propagation, 29 noise, and 32 reverberation models. Propagation models were categorized according to ray theory, multipath expansion, normal mode, fast field, and parabolic approximation formulations; further distinctions were made between range-independent and range-dependent solutions. Noise models included ambient noise and beam-noise statistics models. Reverberation models included cell and point-scattering formulations. The 44 sonar performance models included active sonar models, model operating systems, and tactical decision aids. Active sonar models integrated basic acoustic models, signal-processing models, and supporting databases into cohesive operating systems organized to solve the sonar equations. Model operating systems provided a framework for the direct linkage of data-management software with computer-implemented codes of acoustic models. Tactical decision aids represented a form of engagement-level simulation that blended environmental and sonar performance information with tactical rules. The overall inventory increased by 5 models per year; historical references are maintained in the fifth edition of Underwater Acoustic Modeling and Simulation.

Improving the speed of acoustic propagation modeling, for sonar training applications, with a 3D Gaussian ray bundling model

This research improves the calculation speed of acoustic propagation modeling, for sonar training applications in littoral environments, by implementing a 3D Gaussian ray bundling model in the geodetic coordinates of the environmental databases. Tactical decision aids currently transform the three-dimensional environment into two dimensional radials, then compute acoustic propagation as a function of range and depth. This allows them to analyze millions of range, depth, and bearings for potential targets locations in a few minutes. But, it assumes that the cost of transformation is small compared to the speed benefit of computing propagation in Cartesian coordinates. This assumption is violated in applications where the geometry of the sensors and targets is rapidly evolving, results are strongly dependent on location, and answers must be produced faster than real time. Instead of relying on advancements in computer hardware, this research focuses on the development of a new algorithm to compute bistatic, broadband, transmission loss, and reverberation for 100 active sonar acoustic contacts on commodity laptop hardware, at rates ten times faster than the speed of sound, with no measurable impact on accuracy. [Work supported by the High Fidelity Active Sonar Training (HiFAST) Project at the U.S. Office of Naval Research.]

Achieving distributed decision-making using BDI and Coo^2 for future Distributed Tactical Decision Aids

Achieving distributed decision-making using BDI and Coo^2 for future Distributed Tactical Decision Aids

Improved Active Sonar Tactical Support by Through-the-Sensor Estimation of Acoustic Seabed Properties

Accurate environmental information is required for obtaining confident sonar performance predictions. This environmental information is, however, often unreliable or unavailable. To support antisubmarine warfare (ASW) operations, a through-the-sensor approach has been developed in which relevant acoustic seabed properties are derived from reverberation data, and a demonstrator system has been installed on a Royal Norwegian Navy frigate. It determines relevant acoustic seabed parameters from the reverberation data near real time. This demonstrator system has been validated in several sea trials conducted off the coast of Bergen, Norway. The acoustic seabed parameters derived in these trials have a good correspondence with the available prior information. Furthermore, the results show that acoustic seabed parameters derived from reverberation data in previous trials can be used to improve reverberation prediction for subsequent trials, even when environmental conditions, i.e., sound-speed profiles, are different. Because the demonstrator makes information on acoustic seabed properties directly available for in situ sonar performance prediction, it can be used as a tactical decision aid.

Effectiveness Assessment of Tactical Laser Engagement Scenarios in the Lower Atmosphere

This study quantifies the effectiveness of proposed high-energy tactical laser missions, such as the Advanced Tactical Laser Advanced Concept Technical Demonstration and the Electric Laser on a Large Aircraft program, with consideration of simulated engagement scenarios in the lower atmosphere or troposphere, and establishes the need for a high-energy laser tactical decision aid. The simulations can be varied by geographic location and recent/ current atmospheric weather conditions. The atmospheric effects are defined through the Air Force Institute of Technology Center for Directed Energy high-energy laser end-to-end operational simulation model. This model enables the creation of vertical profiles of temperature, pressure, water vapor content, optical turbulence, and atmospheric particulates and hydrometeors as they relate to line-by-line layer extinction coefficient magnitude at wavelengths from the ultraviolet to the radio frequency. The expected propagation performance is assessed at the wavelength of 1:315 m in tactical laser engagement scenarios at a representative midlatitude site. Seasonal and boundary-layer variations (summer and winter) and time-of-day variations for a range of relative humidity percentile conditions are considered to determine optimum efficiency in a specific environment. Each atmospheric particulate/hydrometeor is evaluated based on its wavelength-dependent forward and off-axis scattering characteristics and absorption effects on the propagating environment. In addition to realistic vertical profiles of molecular and aerosol absorption and scattering, correlated optical turbulence profiles in probabilistic (percentile) format are used. The physically correct atmospheric characterizations used in a high-energy laser end-to-end operational simulation demonstrate the usefulness of implementing an engineering performancemodel with current meteorological conditions to a mission plan and optimize potential tactical high-energy laser combat engagements.

Modeling uncertainty in transmission loss due to spatio-temporal variation in environmental parameters

Tactical prediction and decision aid tools require acoustic propagation modeling. The effectiveness of these tools relies on knowledge of the transfer function between model inputs - either measured or predicted - and model outputs. Of particular interest is this transfer when inputs are uncertain and characterized statistically. The Recognized Environmental Picture experiment 2011 (REP11) was designed to provide observations of spatio-temporal variability in oceanographic and acoustic quantities. REP11 was comprised of multiple runs of co-located and contemporaneous oceanographic and acoustic measurements repeated over twenty-four hours. Acoustic measurements were made using a broad-band source towed along radials from a fixed receiver array. The sound speed field in the water column was sampled independently during each run using gliders, towed instruments, and moorings, each having a different spatio-temporal resolution. Due to the nature of the ocean environment, the sound speed field varied both in time and space for each traversal of the track, yielding a suite of realizations representing the sensitivity of acoustic pressure to spatio-temporal variations in the environment. Based on these data, the statistics of transmission loss from propagation simulations using the observed sound speed fields are compared to the statistics of the measured acoustic pressure fields.

Correlating measured oceanographic and acoustic variability toward understanding uncertainty transfer

The Recognized Environmental Picture experiment 2011 (REP11) was conducted to support research in the areas of battlespace characterization, quantifying uncertainty, and decision support. By integrating results from these three areas, the goal is to incorporate physics based uncertainty transfer in models driving decision support tools. Generically, this is accomplished by parameterizing the environment according to need and providing the best knowledge available for each parameter including uncertainty. Experimentally, the research requires information on both the input and output sides of acoustic propagation models used for tactical prediction or decision aids. This talk describes an experimental effort to contemporaneously measure both oceanographic and acoustic quantities over a wide range of spatio-temporal scales using a combination of mobile, autonomous, and fixed assets. By measuring these quantities over the course of several days and repeating set geometries, many realizations of the oceanographic and acoustic fields were obtained. These data will be examined with respect to correlations between observed variability in the environment and variability in the measured acoustic fields.

A review of recent developments in underwater acoustic modeling.

This is the fifth paper in a series of reviews presented at 8-year intervals starting in 1979 [J. Acoust. Soc. Am. 65, S42 (1979); 82, S102 (1987); 97, 3312 (1995); 114, 2430 (2003)]. All surveys cover basic acoustic models and sonar-performance models. Basic acoustic models include propagation, noise, and reverberation models. Propagation models are categorized according to ray theory, multipath expansion, normal mode, fast field, and parabolic approximation formulations; further distinctions are made between range-independent and range-dependent solutions. Noise models include ambient noise and beam-noise statistics models. Reverberation models include cell and point-scattering formulations. Sonar-performance models include active sonar models, model operating systems, and tactical decision aids. Active sonar models integrate basic acoustic models, signal processing models, and supporting databases into cohesive operating systems organized to solve the sonar equations. Model-operating systems provide a framework for the direct linkage of data-management software with computer-implemented codes of acoustic models. Tactical decision aids represent a form of engagement-level simulation that blend environmental and sonar-performance information with tactical rules. The current inventory of underwater acoustic models comprises 128 propagation models, 21 noise models, 28 reverberation models, and 35 sonar-performance models. Since 1979, approximately five models have been added to the inventory each year.

Overview of U.S. Navy Operational Oceanographic Models in Support of Acoustic Applications

The Naval Oceanographic Office operational global 1/8° Navy Coastal Ocean Model assimilates satellite and in‐situ data to produce daily 72‐hr forecasts. Output includes 3D fields of temperature, salinity, u‐ and v‐components of ocean currents at standard depth levels, and these support derived fields including sound speed and sonic layer depth. The global model provides initial/boundary conditions for nested regional models, primarily relocatable NCOM. The relocatable NCOM modeling system can be set up quickly for areas of interest, includes river and tidal forcing, and is forced with a high‐resolution atmospheric mesoscale model. Local and remote observations are incorporated into the models through the Navy Coupled Ocean Data Assimilation system, which assimilates sea surface temperature data from satellite, ships and buoys, profile data from floats and gliders, xbt's, CTD's, fixed and drifting buoys as well as altimeter‐derived sea surface heights and ice concentration. In this presentation we will discuss how the operational ocean models feed into acoustic prediction models and tactical decision aids, the role glider observations will play in the modeling strategy, the use of ensembles to provide improved prediction error estimates and guide new observations, and future plans.

Operational Impacts of the Environment on Mid-Frequency Navy Sonar Systems In Shallow Water

The coastal oceans represent a challenging domain for mid-frequency maritime Anti-Submarine Warfare (ASW) sonar systems to operate effectively. Information on the advantages and disadvantages of, as well as general tactical employment criteria for the prevalent types of active mid-frequency sonar systems found in the world's navies is provided. Operational performance of these systems, which include hull-mounted sonars, monostatic buoys and multistatic active systems, as well as dipping sonars, is always affected by shallow water environmental parameters. These acoustic and oceanographic factors include frequent bottom interactions of the transmitted acoustic energy, highly variable sound speed and noise fields, strong coastal currents and high levels of acoustic clutter. Accurate and timely four-dimensional sensor performance predictions and optimization recommendations can mitigate some of the negative impact of the environment on sonar detection ranges. We discuss the trade-offs and assumptions made by modern computer-based tactical decision aids to deliver the most accurate environmental information balanced by the need to deliver these data in tactical time frames useful to the ASW mission planner and sonar operator at sea. We will also present thoughts on the quantification of acoustic uncertainty in support of ASW operations and the need for high-fidelity active sonar training systems.

Systemic approach to performance prediction and the exploitation of environmental information in naval systems

Interoperability of systems and implementation of network enabled capabilities are at the heart of defense transformation. By providing extensive capabilities for data gathering, processing and presentations, they achieve a greater tactical advantage through superior knowledge of and use of the operational environment. Within the framework of the deployment of the new French Navy information system SIC21, a system of systems is being developed in order to support the implementation of the NATO concept of Recognized Environmental Picture (REP). The metasystem established allows for the assimilation of Rapid Environmental Assessment (REA) data, and for a local or remote production of the REP. In order to support decision making and to guide actions local exploitation of the REP is carried out through embedded tactical decision aids. They rely on advanced performance prediction tools including propagation modelling capabilities called in simulation scenarios. The aims of the implemented models are to predict performances at the appropriate level of granularity, to provide a confidence level on the proposed tactical picture, to define the appropriate level of marine environmental knowledge that should be acquired, to optimise sensor settings, and finally to provide inversion tools for the REA, ensuring consistency with forward modelling used in performance prediction.

Verification and training of real-time forecasting of multi-scale ocean dynamics for maritime rapid environmental assessment

The Harvard Ocean Prediction System (HOPS) provides real-time and hindcast, multi-scale oceanic field estimates for Maritime Rapid Environmental Assessment (MREA). Results of aspects of the validation, calibration and verification of HOPS for MREA03 and MREA04 are presented, with implications for future MREA exercises. A new method of model training, via bias correction through the use of limited data, was applied to MREA03 and shown to produce significant forecast improvement while reducing computational requirements. Advances in, and the demand for, adaptive modeling, require that aspects of validation, calibration and verification be carried out in real-time in order to expand the usage and relevance of dynamical forecast-based MREA tactical decision aids.

Mine Countermeasures (MCM) Tactical Decision Aids (TDAs), A Historical Review

Mine Countermeasures (MCM) Tactical Decision Aids (TDAs), A Historical Review

Robustness and constraints of high-frequency ambient noise inversion for sonar performance estimation

Perhaps the most dominant source of error in sonar performance estimation in shallow waters is the geoacoustic description of the seafloor. Various investigators have studied the possible use of ambient noise to infer some key parameters such as the critical angle, geoacoustic properties, or bottom loss. Most operational sonar performance models and tactical decision aids require the bottom loss as a function of grazing angles and frequency to describe the reflected acoustic energy off the ocean floor. Harrison and Simons [Harrison &amp; Simons, ‘‘Geoacoustics inversion of ambient noise: A simple method,’’ J. Acoust. Soc. Am. 112, 1377 (2002)] described a simple measurement approach to infer the bottom loss from ambient noise measurement on a vertical line array. This approach is well suited as an environmental measurement approach during naval operations. The robustness and operational constraints of this measurement approach are quantified using a high-frequency ambient noise model that accounts for wind, shipping, and thermal noise [Ferat &amp; Arvelo, ‘‘Mid-Frequency Ambient Noise Directivity And Array Response in Range-Dependent Environments,’’ High-frequency Ocean Acoustics Conference Proceedings, 2004)]. The effects of array tilt, nearby shipping noise, water absorption, thermal noise, surface-noise dipole pattern, and array beam response on sonar performance estimation are demonstrated. Mitigating factors to maximize estimated bottom loss accuracy will also be outlined.

Objective sampling with EAGLE to improve acoustic prediction accuracy

Some Navy operations require extensive acoustic calculations. The standard computational approach is to calculate on a regular grid of points and radials. In complex environmental areas, this implies a dense grid and many radials (i.e., long run times) to achieve acceptable accuracy and detail. However, Navy tactical decision aid calculations must be timely and exhibit adequate accuracy or the results may be too old or too imprecise to be valuable. This dilemma led to a new concept, OGRES (Objective Grid/Radials using Environmentally-sensitive Selection), which produces irregular acoustic grids [Rike and DelBalzo, Proc. IEEE Oceans (2002)]. Its premise is that physical environmental complexity controls the need for dense sampling in space and azimuth, and that transmission loss already computed for nearby coordinates on previous iterations can be used to predict that complexity. Recent work in this area to further increase accuracy and efficiency by using better metrics and interpolation routines has led to the Efficient Acoustic Gridder for Littoral Environments (EAGLE). On each iteration, EAGLE produces an acoustic field for the entire area of interest with ever-increasing resolution and accuracy. An example is presented where approximately an order of magnitude efficiency improvement (over regular grids) is demonstrated. [Work sponsored by ONR.]

NAVDAS: Formulation and Diagnostics

Abstract The Naval Research Laboratory Atmospheric Variational Data Assimilation System (NAVDAS) is a three-dimensional variational data assimilation suite for generating atmospheric state estimates to satisfy a variety of navy needs. These needs range from global initial conditions for navy global prediction models to environmental input into forward-deployed shipboard tactical decision aids. In common with many other U.S. Navy applications, the NAVDAS system has been designed to be robust, flexible, and portable. In particular, it can perform central site global assimilation on massively parallel machines as well as local data assimilation on workstations with the same code. NAVDAS is an observation space algorithm. The preconditioned conjugate gradient method is used as the descent algorithm to minimize the three-dimensional cost function. The number of iterations required to reach convergence is minimized through the use of dual block diagonal preconditioners with Choleski decomposition. Vertical eige...

TACT: a tactical decision aid using a CERES based wheat simulation model

A decision support system (DSS) was developed in consultation with wheat farmers in the mediterranean wheat growing region of Western Australia. This system is targeted at decisions to be made at the start of the season and provides information about changes in the yield distribution of wheat given seasonal conditions to date. The DSS also access to historical weather records, which may be analysed according to simple, user defined rules.

An Overview of Fleet Numerical Oceanography Center Operations and Products

Abstract The environment is a critical factor to the safe, effective operations of the U.S. Navy. In support of our global peacekeeping mission, the fleet must have timely and accurate forecasts of environmental conditions from the top of the stratosphere to the bottom of the ocean, 24 hours a day, 7 days a week. The hub of this support is the Fleet Numerical Oceanography Center (FLENUMOCEANCEN) located at Monterey, California. As the navy's primary operational processing center for global oceanographic and atmospheric analyses and predictions, FLENUMOCEANCEN provides numerical environmental products to meet the needs of the navy, as well as a full spectrum of oceanographic products to support the Department of Defense. All products are based on the center's extensive global atmospheric and oceanographic database, sophisticated long-range forecast models, and tailored tactical decision aids in support of specific weapons and sensor systems. This paper briefly describes FLENUMOCEANCEN's data sources, compu...