Information Science

Cooperative Control of Robotic Aircraft

A document reviews a multidisciplinary research program oriented toward development of a rigorous theoretical foundation, and scalable analytical tools and paradigms, for construction of cooperative, networked control for numerous autonomous and semi-autonomous aircraft. This research has addressed issues affecting the design of robust autonomous vehicle systems that could operate in highly uncertain environments, form teams, manage information, and cooperate in deployment, allocation of tasks, and searches. Significant accomplishments are reported in three areas:

Deployment and Task Allocation

Algorithms for deployment of aircraft for surveillance have been developed. The algorithms run in real time aboard the aircraft, routing the aircraft to optimal locations, coordinating among the aircraft, thereby enabling efficient deployment throughout a geographic region.

Verification and Hybrid Systems

Advances have been made in the theory of hybrid input-output automata and in techniques, based on this theory, that enable off-line automatic verification and validation of safety and liveness of cooperative control algorithms.

Information Management for Cooperative Control

An information theory produced in this research has yielded significant contributions to the design of robust communication protocols featuring cooperative routing schemes that take advantage of network layer diversity and delay adaptation to increase reliability over wireless networks with fading channels.

Posted in: Briefs, Information Technology, Electronic control systems, Collaboration and partnering, Research and development, Robotics, Unmanned aerial vehicles

Fusion of Image- and Inertial-Sensor Data for Navigation

Amethod of real-time fusion of readout data from electronic inertial and image sensors for passive navigation has been developed. By "passive navigation" is meant navigation without the help of radar signals, Lidar signals, Global Positioning System (GPS) signals, or any other signals generated by on-board or external equipment. The concept of fusion of image- and inertial- sensor data for passive navigation is inspired by biological examples, including those of bees, migratory birds, and humans, all of which utilize inertial and imaging sensory modalities to pick out landmarks and navigate from landmark to landmark with relative ease. The present method is suitable for use in a variety of environments, including urban canyons and interiors of buildings, where GPS signals and other navigation signals are often unavailable or corrupted.

Posted in: Briefs, Information Technology, Mathematical models, Navigation and guidance systems, Data management

C++ Architecture for Simulating UAVs

A conference paper describes the use of the CADAC++ software system for simulating operations of uninhabited aerial vehicles (UAVs) in conjunction with moving ground targets while interacting with other UAVs and with satellites that assist in targeting. CADAC++ was developed by rewriting the prior Fortran-language CADAC software to take advantage of features of C++ that enable multiple instantiation of UAVs, targets, and satellites, thereby enabling the study of such phenomena as fly-out trajectories, third-party targeting, and distributed information sharing. [CADAC (Com puter Aided Design of Aerospace Con cepts) is chiefly an engineering tool to aid in developing aerospace vehicles.] The architecture of CADAC++ is based on the hierarchical structure of inherited classes, wherein, among other things, every instantiated vehicle object is encapsulated with its methods and data. The paper discusses this architecture in more detail, outlining its class structure and a global data bus through which encapsulated vehicle-objects communicate. The paper then discusses a simulation involving a generic UAV model having five degrees of freedom in order to demonstrate the interactive features of the simulation and to support the conclusion that C++ is the programming environment of choice for networked simulations.

Posted in: Briefs, Information Technology, Computer simulation, Satellites, Unmanned aerial vehicles

Overcoming Obstacles to DoD Software Technology Transition

The term "Software Wind Tunnel" (SWiT) denotes an institution proposed to be established as a means of overcoming obstacles that, heretofore, have impeded technology transition in connection with research on, and development and utilization of, software needed for software- intensive systems of the Department of Defense (DoD). The term "technology transition" should not be confused with the term "technology transfer," which denotes a process in which an item of technology developed by or for the government is transferred to industry (usually) or vice versa. Instead, "technology transition" denotes a process in which an item of technology is made to evolve from its developmental form into a mature form and in which that item is adopted by its intended end users.

Posted in: Briefs, Information Technology

Magneto-Fluid Dynamics Calculations for Aerodynamics

Governing differential equations, and algorithms to solve the equations numerically, have been developed to enable computational simulation of weakly ionized aerodynamic flows in the presence of electromagnetic fields. The equations and algorithms are intended mainly for application to airflows about, and within the engines of, contemplated hypersonic vehicles. There, strong imposed magnetic fields and perhaps imposed electric fields might be used, variously, for reducing transfer of heat to solid surfaces, for extracting electric energy from flows, or for accelerating or decelerating flows to enhance combustion of fuel or otherwise increase energy efficiency.

Posted in: Briefs, Information Technology

Planning Observations by Unmanned Surface Vessels

Three algorithms, and software that implements the algorithms, have been conceived and analyzed as means of effecting automated planning of scientific observations by a fleet of unmanned surface vessels (USVs) equipped with sensors and operating over a large and possibly changing ocean area. Typical observations envisioned in the development of these algorithms include water-temperature measurements ahead of the path of a hurricane (see figure) and fluorometer readings to track harmful algal blooms.

Posted in: Briefs, Information Technology

Simulation of a Flywheel Energy-Storage System

A computational model has been developed to simulate the operation of a laboratory flywheel energy-storage system that is a subsystem of the Flywheel Attitude Control, Energy Transmission, and Storage (FACETS) system located at Kirtland Air Force Base in New Mexico. The FACETS, which includes three advanced flywheel energy-storage units and an apparatus denoted the Agile Multi- Purpose Satellite Simulator (AMPSS), is used to demonstrate conceptual spacecraft operations involving integral combinations of attitude-control maneuvers and energy-storage operations. The flywheel units include high-hoop-strength carbon composite rotors that turn on magnetic bearings. The flywheels have a maximum rated angular speed of 40,000 rpm, making it possible to store as much a 1 kW·hr of energy in each unit. An air bearing supports the entire AMPSS test article allowing three-axis rotation with minimal damping. In addition to the flywheel units, the system includes DC-to-DC power converters and a three-phase rectifier.

Posted in: Briefs, Information Technology, Computer simulation, Energy storage systems, Flywheels, Spacecraft

Sensor Validation Using Nonlinear Minor-Component Analysis

Aconcept of sensor validation using nonlinear minor-component analysis (NLMCA) has been proposed as a theoretical basis of a sensor fault-detection-and isolation (FDI) module in a fault-tolerant control system of an aircraft jet engine or other complex physical plant. As used here, "sensor validation" signifies, loosely, analysis of the readouts of all the sensors in such a system for the purpose of identifying which (if any) sensors are faulty and, if possible, the magnitudes of the faults. Once a fault in a sensor or any other component was detected and isolated, the fault-tolerant control system would automatically reconfigure itself to compensate for the effect of that and any other faults so as to maintain acceptable (or as nearly acceptable as possible) control performance of the plant even in the presence of the faults. In the case of a faulty sensor, the system would utilize any available analytical redundancy among all sensor signals to estimate the value of the physical quantity desired to be measured by that sensor, and that value would then be used for feedback control.

Posted in: Briefs, Information Technology, Finite element analysis, On-board diagnostics, Sensors and actuators

Enlightened Multiscale Simulation of Biochemical Networks

A continuing research project is dedicated to development of mathematical and software infrastructure in support of post genomics research in systems biology. One near-term objective of the project is to contribute to deeper understanding of the organizational principles of biological networks. A distinguishing theme of this project is a focus on scalable methods of robustness and theoretically sound methods of the use of experimental data to validate (or invalidate) models; this theme stands in contrast to the heretofore prevalent theme of relying purely on simulation.

Posted in: Briefs, Information Technology, Mathematical models, Computer software / hardware, Biological sciences, Product development, Research and development

Error-Free Data Acquisition and Archival for High-Bandwidth Military Applications

Acquiring data from sensors, transporting the data, and then archiving it for future reference has changed dramatically over the last few years. The traditional approach of collecting data from an analog-to-digital converter (ADC) with a small microprocessor to monitor the slow-changing levels of a signal is for the most part no longer adequate. Today's new advanced military systems now employ complex sensors capable of generating streams of data with rates of 100 megabytes and greater. To transfer this high-speed data from the sensor to a processor without losing signal characteristics, designers now must digitize the data at the sensor. To meet this requirement, designers needed a protocol that would transport the digital data with minimum processing or latency. This problem was pursued by several companies, including Curtiss- Wright, and the result was the ANSI/VITA 17.1-2003 Serial Front Panel Data Port standard (S-FPDP).

Posted in: Briefs, Information Technology