Real-Time Optimized Earth Observation Autonomous Planning

Adams, M. et al.

On the Complexity and Distributed Construction of Energy-Efficient Broadcast Trees in Static Ad Hoc Wireless Networks

Evolution of Low-Cost MEMS Inertial Systems

Ash, M.E.

Technical Evaluation Report (TER) on Emerging Military Capabilities Enabled by Advances in Navigation Sensors

Apparent Mass of Parafoils with Spanwise Camber

High Productivity Truck and Bus Lane

Maintaining Network Element Synchronization in the X-38 Fault-Tolerant Parallel Processor

Bergstrom, S.E. et al.

Borenstein, J.T.

Borenstein, J.T. et al.

The Inertial Stellar Compass: a New Direction in Spacecraft Attitude Determination

Timeliner: Automating Procedures on the ISS

Semiconductor Silicon as a Selective Emitter

A Micromechanical Inertial Measurement Unit for Tactical Applications

Adaptive Robust Constrained Matched Filter and Subspace Detection

Diffusion Tensor Model Based Smoothing and Segmentation

Robust Non-Gaussian Matched Subspace Detectors

DiMatteo, R.S. et al.

An Evaluation of GPS M-Code Under Jamming

An Optimal Guidance Law for Formation Flying and Stationkeeping

A Si-Based FPW Sensor Array System with Polymer Microfluidics Integrated on a PCB

Duwel, A. et al.

Edsall, A.

Gilmore, J.P. et al.

Hammett, R.

Homer, M.L.

The Silicon Oscillating Accelerometer: a MEMS Inertial Instrument for Strategic Missile Guidance

Houston, K.M. et al.

Onboard Determination of Vehicle Glide Cabability for Shuttle Abort Flight Management (SAFM)

Apollo and Space Shuttle On-Board Navigation Systems: Application of Kalman Filtering Techniques

Kim, E.S. et al.

Kim, E.S. et al.

Kondoleon, A.S. et al.

Krupadanam, A.S. et al.

Malcos, M.

Aluminum Nitride Chip Carrier for Microelectromechanical Sensor Applications

Martorana, R.T.

Mescher, M.J. et al.

Mettler, B. et al.

Nervegna, M. et al.

Racine, R. et al.

System Status in the X-38 Fault-Tolerant Parallel Processor

Performance Optimization of a Maneuvering Reentry Vehicle Using a Legendre Pseudospectral Method

Ricard, M. et al.

Ricard, M. et al.

Sargent, D. et al.

Using Taguchi Analysis in the Recapture of a Legacy Production Process for a Precision Accelerometer Float

Reliability and Survivability in the Reduced Ship's Crew by Virtual Presence System. Revision

Control Allocation for the Next Generation of Entry Vehicles

Spangler, G.E. et al.

Modernization of a High-Precision, Heavy Payload Centrifuge

Thermo-Optical Switches Using Coated Microsphere Resonators

Turney, D. et al.

Abramson, M.; Carter, D.; Kolitz, S.; Ricard, M.; Greenfeld, I.

Autonomously Optimizing Multi-Spacecraft Mission Managing System

Core Technologies for Space Systems. Held in Colorado Springs, CO, 11/19/2002 to 11/21/2002. Sponsored by: IEEE/AAS/AIAA. (Draper Report no. P-4057)

Abstract: Earth monitoring systems of the future may include large numbers of inexpensive small satellites, tasked in a coordinated fashion to observe both long-term and transient targets. For best performance, a tool that helps operators optimally assign targets to satellites will be required. Initial results from algorithms developed for real-time optimized autonomous planning of large numbers of small single-sensor Earth observation satellites are presented. The algorithms will reduce requirements on the human operators of such a system of satellites, ensure good utilization of system resources, and provide the capability to dynamically respond to temporal terrestrial phenomena. The initial real-time system model handles up to 100 satellites and large number of points of interest on Earth (e. g., hurricanes, volcanoes,  forest fires) with the objective to maximize the total science value of observations over time. An integrated approach using integer programming, network optimization, and astrodynamics is used to calculate optimized observation and sensor tasking plans. Test scenarios and associated experiments consisting of hypotheses, test procedures, and results are presented.

Subjects: AUTONOMOUS ORBITAL SYSTEMS, EARTH OBSERVATION SATELLITE (EOS), SMALL SATELLITES

Abramson, M.; Carter, D.; Kolitz, S.; Ricard, M.; Scheidler, P.

Real-Time Optimized Earth Observation Autonomous Planning

Earth Science Technology Conference (ESTC). 2nd. Held in Pasadena, CA, 06/11/2002 to 06/13/2002. Sponsored by: NASA. (Draper Report no. P-3993)

Abstract: Earth monitoring systems of the future may include large numbers of inexpensive small satellites, tasked in a coordinated fashion to observe both long-term and transient targets. For best performance, a tool that helps operators optimally assign targets to satellites will be required. We present initial results from algorithms developed for real-time optimized autonomous planning of large numbers of small single-sensor Earth observation satellites. The algorithms will reduce requirements on the human operators of such a system of satellites, ensure good utilization of system resources, and provide the capability to dynamically respond to temporal terrestrial phenomena. Our initial real-time system model consists of approximately 100 satellites and large number of points of interest on Earth (e.g., hurricanes, volcanoes, forest fires) with the objective to maximize the total science value of observations over time. Several options for calculating the science value of observations include the following: 1) total observation time, 2) number of observations, and the 3) quality (a function of e.g., sensor type, range, slant angle) of the observations. An integrated approach using integer programming, network optimization and astrodynamics is used to calculate optimized observation and sensor tasking plans.

Subjects: EARTH OBSERVATIONS (FROM SPACE), AUTONOMY, EARTH OBSERVATION SATELLITE (EOS), ALGORITHMS, REAL TIME SYSTEMS

Adams, M.; Hall, W.; Hanson, M.; Zacharias, G.

Mixed Initiative Planning and Control Under Uncertainty

Unmanned Aerospace Vehicles, Systems, Technologies, & Operations. 1st. Held in Portsmouth, VA, 05/20/2002 to 05/22/2002. Sponsored by: AIAA. (Draper Report no. P-4005)

Abstract: A hierarchical architecture is developed to provide closed-loop, mixed initiative planning and control for distributed force teams of unmanned air vehicles in an uncertain military operational environment. The hierarchical architecture derives from a rigorous decomposition of the problem that preserves system-level objectives while respecting local constraints and defines the interactions and information exchanges between decision-making nodes at each level. An intelligent adversary is addressed in planning and decision-making through coupling of uncertainty in state estimation and the risk associated with possible system states. The proposed hierarchical structure also accommodates human decision-makers and operators at any level within any planning and control function. This is made possible by the incorporation of human-centered design principles and human behavior representation models that enable human operators and machine automation to function as a cooperative team. Game-theoretic estimation and control techniques capture the actions of an intelligent adversary in order to improve performance under imperfect state knowledge. The problem decomposition and the use of experimentally-derived heuristics make this approach computationally tractable. Computational cognitive process models capture expert human decision-making, thereby providing a foundation for bridging the gap between engineering estimation/optimization algorithms and naturalistic human machine interfaces (HSIs) that support effective mixed initiative monitoring, planning, and control in dynamic environments.

Subjects: MICA, CLOSED-LOOP SYSTEMS (FEEDBACK CONTROL), UNMANNED AERIAL VEHICLES (UAV), HIERARCHICAL SYSTEMS, UNCERTAINTY, DECISION-MAKING

Ahluwalia, A.; Modiano, E.; Shu, L.

On the Complexity and Distributed Construction of Energy-Efficient Broadcast Trees in Static Ad Hoc Wireless Networks

Conference on Information Science and Systems (CISS). 36th. Held in Princeton, NJ, 03/20/2002 to 03/22/2002. Sponsored by: Princeton University. (Draper Report no. P-3983)

Abstract: We address the energy-efficient broadcasting problem in ad hoc wireless networks. First, we show that finding the minimum energy broadcast tree is NP-complete and develop an approximation algorithm, which computes suboptimal solutions in polynomial time. We present a distributed algorithm that computes all N possible broadcast trees simultaneously with O(N2) message complexity. We compare our algorithm's performance to the best known centralized algorithm, and show that it constructs trees consuming, on average, only 18% more energy.

Subjects: BROADCASTING, WIRELESS COMMUNICATIONS, ALGORITHMS

Anderson, R.; Barbour, N.; Connelly, J.; Hanson, D.; Kourepenis, A.; Sitomer, J.; Ward, P.

Evolution of Low-Cost MEMS Inertial Systems

Emerging Military Capabilities Enabled by Advances in Navigation Sensors. Held in Istanbul, Turkey, 10/14/2002 to 10/16/2002. Sponsored by: NATO. (Draper Report no. P-4048)

Abstract: The performance of MEMS inertial technology has evolved from automotive quality to that approaching tactical-grade quality (1 deg/h, 1 mg). This evolution is a direct result of advances made in the key technology areas driven by gun-launched projectile requirements. The application of silicon MEMS inertial technology to competent munitions efforts began in the early 1990s. Initially, gun hardness was demonstrated at the sensor level, although the bias-and-scale factor of these gyros and accelerometers was mostly suitable for automotive or commercial use. Subsequently, development programs were initiated to develop gun-hard inertial systems with greatly improved sensor performance, and with a goal of low production cost. This paper discusses the evolution of low-cost MEMS inertial system technology development for guided projectile INS/GPS systems and high-performance IMUs. The evolution in sensors and packaging to realize performance improvement and system size reduction are presented. Recent data from the culmination of a 3-year effort to develop an 8-in3 IMU are summarized, and represent the highest performance to date for an all-silicon IMU. Further investments in gun-hard silicon MEMS systems will ultimately realize IMUs that are smaller (less than 2 in3), higher performing (1 deg/h and less than 1 mg), and lower in cost (less than $1200 per IMU and $1500 per INS/GPS) than is achievable in any competing technology.

Subjects: MICROELECTROMECHANICAL SYSTEM (MEMS), LOW-COST INERTIAL GUIDANCE, INERTIAL MEASUREMENT UNIT (IMU), INERTIAL NAVIGATION SYSTEMS (INS), GLOBAL POSITIONING SYSTEM (GPS)

Ash, M.E.

Equipping GPS Satellites with Accelerometers and Satellite-to-Satellite Observables

Institute of Navigation National Technical Meeting. Held in San Diego, CA, 01/28/2002 to 01/30/2002. Sponsored by: ION. (Draper Report no. P-3934)

Abstract: Millimeter-level accuracy applications of terrestrial GPS phase tracking can be done more robustly with global rather than regional accuracy if the GPS satellites are equipped with (1) accelerometers to measure rather than model nongravitational accelerations, (2) satellite-to-satellite phase tracking as well as ranging cross links to work around inadequately modeled atmospheric propagation effects, and (3) gyroscopes for better satellite attitude control. More complete general relativity modeling is also needed in the orbit fitting and site coordinate estimation process, for which it could be advantageous to employ a combination of Kalman filtering on the orbital motions and maximum likelihood estimation on the site coordinates, accelerometer biases, and other parameters.

Subjects: GLOBAL POSITIONING SYSTEM (GPS), ACCELEROMETERS, KALMAN FILTERING

Barbour, N.M.

Technical Evaluation Report (TER) on Emerging Military Capabilities Enabled by Advances in Navigation Sensors

Emerging Military Capabilities Enabled by Advances in Navigation Sensors. Held in Istanbul, Turkey, 10/14/2002 to 10/16/2002. Sponsored by: NATO. (Draper Report no. P-4068)

Subjects: NAVIGATION, SENSORS, MICROELECTROMECHANICAL SYSTEM (MEMS)

Barrows, T.M.

Apparent Mass of Parafoils with Spanwise Camber

Journal of Aircraft, Vol. 39, No. 3, May-June 2002. pp. 445-451. (Draper Report no. P-3865-REV-A)

Abstract: For an arbitrarily shaped body, there may be more than one center of apparent mass. The apparent mass of a parafoil shape for motions along various axes is computed using potential flow analysis. From this, the 6 x 6 apparent mass matrix about some reference point is computed. Parametric forms for estimating the terms are given. The existence of multiple mass centers results in off-diagonal terms in this matrix, which couple the translational and rotational motions. It is shown how the nondiagonal 6 x 6 apparent inertia matrix about a certain reference point can be used to compute the corresponding apparent mass matrix at any other reference point. Dynamic equations including nonlinear terms are presented.

Subjects: PARAFOILS, APPARENT MASS, PARAMETRIC ANALYSIS, NONLINEAR EQUATIONS

Barrows, T.M.

High Productivity Truck and Bus Lane

Applications of Advanced Technology in Transportation. Held in Cambridge, MA, 08/05/2002 to 08/07/2002. Sponsored by: ASCE. (Draper Report no. P-3979)

Abstract: A high productivity truck and bus lane is described, which includes a U-shaped guideway, built along interstate right-of-way, to serve both passengers and freight. Passengers would used a Tracked Ram Air Cushion Bus (TRACBUS), a dual-mode vehicle that can travel on a highway at 60 mph and can also enter the guideway and travel at speeds of 200 mph or greater. The guideway is used for "truck trains" during the hours between midnight and 6 a.m., The TRACBUS uses aerodynamic suspension and propulsion for operation on a guideway at high speeds, and retractable wheels for low speeds. There are movable control surfaces in the front and rear of the vehicle that provide control of pitch, yaw, roll, and sway. There is a pair of ducted fans in the front, each of which is powered by a gas turbine. The wake from the fans is ducted under the vehicle and adds to the lift. At low speeds, including all highway operations, the fans are decoupled and the turbine is used to power a pair of drive wheels.

Subjects: TRACKED RAM AIR CUSHION BUS (TRACBUS), TRUCKS, BUS, INTELLIGENT VEHICLE/HIGHWAY SYSTEM

Beilin, S.

Maintaining Network Element Synchronization in the X-38 Fault-Tolerant Parallel Processor

International Conference on Dependable Systems and Networks (DSN). Held in Bethesda, MD, 06/23/2002 to 06/26/2002. Sponsored by: IEEE. (Draper Report no. P-4021)

Subjects: X-38, SYNCHRONIZATION, PARALLEL PROCESSORS, FAULT TOLERANCE

Bergstrom, S.E.; Proulx, R.J.; Cefola, P.J.

Atmospheric Density Correction Using Observational Data

Astrodynamics Specialist Conference. Held in Reston, VA, 08/05/2002 to 08/08/2002. Sponsored by: AIAA/AAS. (Draper Report no. P-3931)

Abstract: Many inaccuracies in the determination and prediction of satellite orbits in the low earth orbit (LEO) range are due to errors in atmospheric drag modeling. These errors can theoretically be reduced by using observational data in real time to enhance an existing atmospheric density model. An algorithm has been developed to compute a linear correction term to the atmospheric density model in order to improve the model accuracy. The algorithm has previously been validated using simulated data. This paper studies the application of the algorithm to a set of real observations.

Subjects: LOW EARTH ORBIT (LEO), ATMOSPHERIC DENSITY, ALGORITHMS

Borenstein, J.T.

Advances in BioMEMS

Science and Foundation of Nanosystems (NY-NanoTech) (UNYVAC). Held in Troy, NY, 08/06/2002 to 08/08/2002. Sponsored by: AVS. (Draper Report no. P-4034)

Subjects: MICROELECTROMECHANICAL SYSTEM (MEMS), BIOLOGY, SPECTROMETERS, ION MOBILITY, TISSUE ENGINEERING

Borenstein, J.T.; Terai, H.; King, K.R.; Weinberg, E.J.; Kaazempur-Mofrad, M.R.; Vacanti, J.P.

Microfabrication Technology for Vascularized Tissue Engineering

Engineered Tissue Growth (ETG). Held in Pittsburgh, PA, 03/19/2002 to 03/19/2002. Sponsored by: ETG. (Draper Report no. P-4003)

Abstract: This work describes the application of advanced microfabrication technologies, including silicon micromachining and polymer replica molding toward the field of tissue engineering of complex tissues and organs. As a general approach, tissue engineering of skin, bone, and cartilage using cell transplantation on biodegradable matrices has achieved great success. However, such techniques encounter difficulties when applied to complex tissues and vital organs. The principal limitation for such applications is the lack of an intrinsic blood supply for the tissue engineered organ, which experiences significant cell death when the tissue thickness is increased above the 1 - 2 mm range. In this work, the concept of microfabricated scaffolds is introduced, with the goal of producing organ templates with feature resolution of 1 micron, well in excess of that necessary to fashion the capillaries that comprise the microcirculation of the organ. Initial efforts have resulted in high-resolution biocompatible polymer scaffolds produced by replica molding from silicon micromachined template wafers. These scaffolds have been successfully seeded with endothelial cells in channels with dimensions as small as the capillaries.

Subjects: MICROFABRICATION, TISSUE ENGINEERING

Brady, T.; Tillier, C.; Brown, R.; Jimenez, A.; Kourepenis, A.

The Inertial Stellar Compass: a New Direction in Spacecraft Attitude Determination

Conference on Small Satellites. 16th. Held in Logan, UT, 08/12/2002 to 08/15/2002. Sponsored by: AIAA/USU. (Draper Report no. P-4018)

Abstract: The Inertial Stellar Compass (ISC) is a real-time, miniature, low-power stellar inertial attitude determination system, composed of a wide field-of-view active pixel star camera and a microelectromechanical system (MEMS) gyro assembly, with associated processing and power electronics. The integrated technologies enable an attitude determination system with an accuracy of 0.1 deg (1 sigma) to be realized at very low power and volume. The attitude knowledge provided by the ISC is applicable to a wide range of space and earth science missions that may include the use of highly maneuverable, stabilized, tumbling, or lost spacecraft. Under the guidance of NASA's New Millennium ST-6 project, Draper Laboratory is currently developing the ISC. Its completion and flight validation will represent a breakthrough in real-time miniature attitude determination sensors. This paper describes system design, development, and validation activities currently underway at Draper.

Subjects: STELLAR INERTIAL GYROSCOPE COMPASSES, MICROELECTROMECHANICAL SYSTEM (MEMS), NEW MILLENNIUM PROGRAM

Brown, R.A.; Braunstein, E.; Brunet, R.; Grace, R.; Vu, T.; Busa, J.; Dwyer, W.

Timeliner: Automating Procedures on the ISS

SpaceOps. Held in Houston, TX, 10/09/2002 to 10/12/2002. Sponsored by: AIAA. (Draper Report no. P-4035)

Subjects: TIMELINER, INTERNATIONAL SPACE STATION (ISS), PROCEDURES, AUTOMATION

Chubb, D.L.; Wolford, D.S.; Meulenberg, A.; DiMatteo, R.S.

Semiconductor Silicon as a Selective Emitter

Thermophotovoltaic Generation of Electricity. 5th. Held in Rome, Italy, 09/16/2002 to 09/18/2002. Sponsored by: AIP. (Draper Report no. P-3904)

Abstract: Using the same semiconductor for both the emitter and photovoltaic (PV) array would make an ideal thermophotovoltaic (TPV) system since the emitter spectral emittance would match the PV array spectral response. Silicon operating in a vacuum is a good candidate since it has a high melting point (1680 K). In this paper, we present both theoretical and experimental results for the spectral emittance of thin (~1-micron) films of pure silicon on sapphire substrates with a platinum film backing on the sapphire. These results show the importance of temperature and film thickness in determining the spectral emittance.

Subjects: THERMOPHOTOVOLTAICS (TPV), SEMICONDUCTORS, EMITTERS, SILICON

Connelly, J.; Kourepenis, A.

A Micromechanical Inertial Measurement Unit for Tactical Applications

Guidance, Navigation, and Control Conference. Held in Monterey, CA, 08/05/2002 to 08/08/2002. Sponsored by: AIAA. (Draper Report no. P-4037)

Abstract: Micromachined silicon inertial sensors offer revolutionary improvements in cost, size, and reliability for guidance, navigation, and control (GN&C). Batch manufacturing techniques produce thousands of virtually identical microelectromechanical system (MEMS) devices, each a few square millimeters in size. Development of inertial MEMS is driven by the high-volume, commercial market that targets modest performance applications at prices below $10 per axis. Draper Laboratory has recently demonstrated higher performance, multi-axis systems using commercial processes for lower-volume tactical applications ranging from guided munitions to microsatellites. More accurate sensors enabled by Deep Reactive Ion Etch technology and new digital electronics are rapidly approaching a bias stabilities of 1 deg/h and 100 micro-g over -40°C to +85°C. Future architectures under development reflect a radical departure from early demonstration systems. New sensors with complementary input axes have led to multi-axis sensor arrays, and new wafer-scale processes, integrating sensor arrays and Application-Specific Integrated Circuits (ASICs), are creating complete systems on a chip.

Subjects: MICROELECTROMECHANICAL SYSTEM (MEMS), INERTIAL MEASUREMENT UNIT (IMU), TACTICAL DEPLOYMENT, ETCHINGS

Desai, M.; Mangoubi, R.

Adaptive Robust Constrained Matched Filter and Subspace Detection

Asilomar Conference on Signals, Systems and Computers. 36th. Held in Pacific Grove, CA, 11/03/2002 to 11/06/2002. Sponsored by: IEEE. (Draper Report no. P-4043)

Abstract: We provide a minmax methodology for formulating adaptively robust and sensitive matched filter and subspace detectors where the signal and interference or structured noise are partially known. The signal and interference subspaces are assumed to reside in conical regions of the measurement space, and their gain parameters can have bounded magnitude. We show that the minmax approach permits the design of a rich variety of matched filter and subspace detectors that vary in their degree of robustness and sensitivity.

Subjects: SUBSPACE DETECTORS, MATCHED FILTERS, ROBUSTNESS

Desai, M.; Kennedy, D.; Mangoubi, R.; Shah, J.; Karl, C.; Markis, N.; Worth, A.

Diffusion Tensor Model Based Smoothing and Segmentation

International Symposium on Biomedical Imaging. Held in Washington, DC, 07/07/2002 to 07/10/2002. Sponsored by: IEEE. (Draper Report no. P-3991)

Abstract: We provide a unified framework for smoothing noisy brain image data along attributes of choice derived from diffusion tensor imaging. The framework is based on a variational segmentation functional approach that outputs smoothed regions within the white matter that are relatively homogeneous with respect to specific diffusion tensor image properties. The smoothed tensor fields and the associated edge fields are recovered in a number of ways, thus illustrating the applicability of the proposed unified framework for smoothing and feature extraction in support of the anatomic identification of white matter fiber systems in the human brain.

Subjects: BRAIN, IMAGING, TENSOR ANALYSIS

Desai, M.; Mangoubi, R.

Robust Non-Gaussian Matched Subspace Detectors

European Signal Processing Conference (EUSIPCO). 11th. Held in Toulouse, France, 09/03/2002 to 09/06/2002. Sponsored by: EURASIP. (Draper Report no. P-3986)

Abstract: We address the problem of matched subspace detection in the presence of arbitrary noise and interferents, or interfering signals that may lie in a possibly unknown subspace, but that nevertheless corrupt the measurements. A hypothesis test that is robust to interferents yet sensitive to the signal of interest is formulated. The test is applicable to a large class of noise density functions. In addition, specific expressions for the generalized likelihood ratio (GLR) detectors are derived for the class of generalized Gaussian noise. The detectors are generalizations of the x2, t, and F statistics used with Gaussian noise. For matched filter detection, these expressions are simpler and computationally efficient. ROC performance results based on simulation demonstrate the superior performance obtained with detectors based on the correct noise model. The results also demonstrate the improved performance robust detectors offer when interferents are present.

Subjects: GENERALIZED LIKELIHOOD RATIO TEST (GLRT), GAUSSIAN NOISE (RANDOM NOISE), DETECTORS, MAGNETIC RESONANCE IMAGERY

DiMatteo, R.S.; Greiff, P.; Finberg, S.L.; Young-Waithe, K.A.; Choy, H.K.H.; Masaki, M.M.; Fonstad, C.G.

Micron-Gap Thermophoto Voltaics (MTPV)

Thermophotovoltaic Generation of Electricity. 5th. Held in Rome, Italy, 09/16/2002 to 09/18/2002. Sponsored by: AIP. (Draper Report no. P-4059)

Abstract: To date, ThermoPhotoVoltaic (TPV) technology has been governed by Planck's Law. To increase the photonic flux from the emitter to the receiver in a TPV system, the temperature must be increased. Higher temperatures lead to materials challenges and higher parasitic system-level thermal losses. In addition, they make it difficult for TPV to compete in many waste heat conversion applications where the available waste heat is at temperatures less than those required for TPV. Planck indicated that his law applies only if the dimensions of the system are large compared to the wavelengths of the radiation. The idea that the electromagnetic energy transfer in a TPV system can be increased by 5 times or more beyond Planck's Law by placing the emitter in close proximity to the photovoltaic receiver has been proposed and studied theoretically, and has been referred to as Micron-gap TPV (MTPV). In this paper, we discuss the theory, the technology, and the experimental results that obtain when the distance between the emitter and receiver surfaces is reduced to submicron dimensions. The dramatic demonstration of this effect is the initial step in the development of a new class of energy conversion devices.

Subjects: MICRON-GAP THERMOPHOTOVOLTAICS (MTPV)

Dowdle, J.R.; Flueckiger, K.

An Evaluation of GPS M-Code Under Jamming

Joint Navigation Conference (JNC). 27th. Held in Orlando, FL, 05/06/2002 to 05/09/2002. (Draper Report no. P-4020)

Subjects: GLOBAL POSITIONING SYSTEM (GPS), JAMMING

D'Souza, C.N.

An Optimal Guidance Law for Formation Flying and Stationkeeping

Guidance, Navigation, and Control Conference. Held in Monterey, CA, 08/05/2002 to 08/08/2002. Sponsored by: AIAA. (Draper Report no. P-3982)

Abstract: With the large number of proposed missions focused on rendezvous, there is a need for the development of optimal guidance laws for formation flying, station-keeping and controlled approach to a target vehicle. Much of the work performed to date involves guidance and control laws based on Linear Quadratic (LQ) methods. A weakness of this approach is that there is no direct control of the time required to transfer between two specified points, not to mention the fact that these control laws are not tractable in closed form. A new closed-form guidance law has been obtained that allows transfers between two points in a specified time. It minimizes the commanded acceleration subject to the Hill-Clohessy-Wiltshire equations of relative motion, and ensuring that the terminal constraints are satisfied. The equations of motion allow for the in-plane motion to be solved separately from the out-of-plane motion. Hence, these can be targeted separately. These guidance laws are applied to two vehicles moving in elliptical motion with respect to each other and also to two vehicles closing on one another.

Subjects: STATION-KEEPING, FORMATION-KEEPING, GUIDANCE LAWS

Dubé, C.E.; Fiering, J.O.; Mescher, M.J.

A Si-Based FPW Sensor Array System with Polymer Microfluidics Integrated on a PCB

Sensors. Held in Orlando, FL, 06/11/2002 to 06/15/2002. Sponsored by: IEEE. (Draper Report no. P-3937)

Abstract: Many methods for fabricating structures for microfluidic-based sensors have been developed in recent years. However, little has been reported on effective methods for integrating these structures into electronic systems for analysis and fluidic delivery. This paper describes a straightforward and versatile fabrication platform for polymer microfluidics that readily accommodates integration with silicon-based sensors, printed circuit, and surface-mount technologies. In particular, we have demonstrated a novel system for distributed delivery to flexural plate wave (FPW) chemical/biological sensor where micromachined fluidic components are combined in a single package with silicon die, multilayer printed circuit board, and surface-mount electronics. In the same fabrication platform, we have demonstrated temperature control of the sensor with 0.1°C precision using integrated metal thin-film heater and sensor elements. This is an important capability for FPW sensors to compensate for temperature-induced drift. We present results for the on-board microfluidic system where the sensor is used to detect changes in the composition of the supplied fluid.

Subjects: FLEXURAL PLATES, BIOLOGICAL SENSORS, CHEMICAL SENSORS, MICROFLUIDICS

Duwel, A.; Weinstein, M.; Gorman, J.; Borenstein, J.; Ward, P.

Quality Factors of MEMS Gyros and the Role of Thermoelastic Damping

International Conference on Microelectromechanical Systems (MEMS). 15th. Held in Las Vegas, NV, 01/20/2002 to 01/25/2002, pp. 214-219. Sponsored by: IEEE. (Draper Report no. P-3935)

Abstract: In this paper, we present new experimental data illustrating the importance of thermoelastic damping in MEMS resonant sensors. We have used MEMS gyroscopes to demonstrate that both the choice of materials and variations in device design can lead to significant differences in the measured Quality (Q) factors of the device. These differences in Q factor can be explained by including the contribution of thermoelastic damping (TED), which varies strongly between the different silicon etch-stop compositions used in this study. Known damping mechanisms such as fluid damping, anchor damping, and electronics damping are minimized and held fixed in this experiment so that materials effects can be isolated.

Subjects: MICROELECTROMECHANICAL SYSTEM (MEMS), DAMPING, RESONANT SENSORS

Edsall, A.

The X-38 Fault-Tolerant Parallel Processor: High Reliability Flight Control Based on COTS Computer Hardware

Future Reusable Launch Vehicles Symposium. Held in Huntsville, AL, 04/11/2002 to 04/12/2002. Sponsored by: AIAA/IAF. (Draper Report no. P-4002)

Subjects: X-38, FAULT TOLERANT PARALLEL PROCESSOR (FTPP), FLIGHT CONTROL SYSTEMS (FCS), COMMERCIAL-OFF-THE-SHELF (COTS), COMPUTER HARDWARE

Gilmore, J.P.; Luniewicz, M.F.; Sargent, D.G.

Enhanced Precision Pointing Jitter Suppression System

LASE: High-Power Lasers and Applications. Held in San Jose, CA, 01/20/2002 to 01/25/2002. Sponsored by: SPIE. (Draper Report no. P-3921)

Abstract: Space based defense systems, such as a Space-Based Laser (SBL), and space-based surveillance systems share a common objective: extremely high resolution line-of-sight (LOS) target imaging. In order to achieve the mission objectives, their beam control subsystem must provide precise LOS pointing and tracking capabilities with suppression of LOS jitter. Draper Laboratory has developed concepts and instrumentation that address these needs based on a stabilized inertial platform mechanization that holds a collimated light source, called the Inertial Pseudo Star Reference Unit (IPSRU). This paper describes the original IPSRU design and a design concept for a new high-performance version of the IPSRU system (HP-IPSRU) that meets the jitter stabilization needs of the SBL. The IPSRU provides an inertially stabilized optical probe beam that provides a precise pointing and tracking reference with nanoradian jitter performance. The IPSRU serves as a master reference for stabilizing imaging and weapon system pointing and tracking. This paper describes the IPSRU system, its measured error allocation and integrated performance. It presents the error budget required to achieving the 5-nrad rms jitter stabilization performance projected to be necessary for an operational SBL system. A conceptual design for the HP-IPSRU is presented.

Subjects: SPACE-BASED LASERS (SBL), LINE-OF-SIGHT JITTER (LOS JITTER), INERTIAL PSEUDO STAR REFERENCE UNIT (IPSRU)

Hammett, R.

Design by Extrapolation: An Evaluation of Fault-Tolerant Avionics.

Digital Avionics Systems Conference. 20th. Held in Daytona Beach, FL. 10/14/2001 to 10/18/2001, pp. 1C51-1C512. Sponsored by: IEEE. IEEE Aerospace and Electronic Systems Magazine, Vol. 17, No. 4, April 2002, pp. 17-25. (Draper Report No. P-3889)

Abstract: Over the past 30 years, safety-critical avionics systems such as Fly-By-Wire (FBW) flight controls, full-authority digital engine controls, and other systems have been introduced on many commercial and military airplanes and spacecraft. Early FBW systems, such as on the F-16 and Airbus A320, were considered revolutionary and were introduced with extreme caution. These early systems and their successors all make use of redundant and fault-tolerant avionics to provide the required dependability and safety, but have used significantly different architectures. This paper examines the different levels of criticality and fault tolerance required by different types of avionics systems, establishes architectural categories of fault-tolerant architectures, and identifies the discriminating features of the different approaches. Examples of discriminators include the level of redundancy, methods of engaging backup systems, protection from software errors, and the use of dissimilar hardware and software. The strengths and weaknesses of the different approaches will be identified. The paper concludes with some speculation on trends for future systems based on this evaluation of previous systems.

Subjects: FLY-BY-WIRE CONTROL; AVIONICS; FAULT-TOLERANT SYSTEMS

Homer, M.L.

Handling Event-Driven Messaging in Distributed Flight Critical Systems

Digital Avionics Systems Conference (DASC). 21st. Held in Irvine, CA, 10/27/2002 to 10/31/2002. Sponsored by: IEEE. (Draper Report no. P-3995)

Abstract: Using events rather than time to schedule messaging between nodes in a distributed avionics architecture can lessen data communication/processing requirements and reduce the cost of system expansion. Regulating bus access via the Flexible Time Division Multiple Access (FTDMA) method promises to enable event-driven messaging without affecting the predictability of message response times. This paper investigates the FTDMA method in a distributed system handling both closed-loop control and discrete event detection/response tasks. Calculations are derived for placing an upper limit on message response times. The formula is then evaluated using empirical data from an experimental setup employing the byteflight communications protocol.

Subjects: MESSAGING, DIGITAL AVIONICS SYSTEM, FLEXIBLE TIME DIVISION MULTIPLE ACCESS (FTDMA)

Hopkins, R.; Miola, J.; Sawyer, W.; Setterlund, R.; Ward, P.

The Silicon Oscillating Accelerometer: a MEMS Inertial Instrument for Strategic Missile Guidance

Missile Sciences Conference. Held in Monterey, CA, 11/05/2002 to 11/07/2002. Sponsored by: AIAA. (Draper Report no. P-4001)

Abstract: The intercontinental ballistic missile (ICBM) and submarine-launched strategic missiles developed over the past 50 years have employed successive generations of increasingly accurate inertial guidance systems. The comparatively short time of guided flight and high acceleration levels characteristic of the ballistic missile application place a premium on accelerometer performance to achieve desired weapon system accuracy. Currently, the U.S. strategic missile arsenal relies on variants of the pendulous integrating gyro accelerometer (PIGA) to meet the high-performance, radiation-hard requirements of the weapon system. However, the PIGA (whose heritage dates back to World War II) is a complex electromechanical instrument, a life-cycle cost drawback that has motivated a search for a more modern, solid-state, strategic accelerometer. Draper Laboratory is currently in the process of developing the Silicon Oscillating Accelerometer (SOA), a Microelectromechanical System (MEMS)-based sensor that has demonstrated in laboratory testing the part-per-million (ppm)/micro-g scale-factor and bias performance stability required of the strategic missile application. The SOA belongs to the generic category of accelerometers known as Vibrating Beam Accelerometers (VBA), which sense acceleration by measuring the change in resonant frequency of beam oscillators under the inertial loading of a proof mass. The SOA differs from conventional VBAs in one important respect; namely, the SOA is a silicon MEMS-based device, as opposed to VBAs, which are typically bulk-fabricated quartz devices. The silicon MEMS process offers several advantages from an accelerometer design standpoint: (1) semiconductor-grade, single-crystal silicon is a perfectly elastic, high-strength structural material; (2) the MEMS process enables the fabrication of very small (millimeter scale in the case of the SOA) resonator elements that are well isolated from the influence of parasitic instrument package stresses; and (3) capacitively-based, electrostatic resonator actuation and sensing that offers great flexibility in designing the SOA resonator elements. This paper will give an overview of the Draper SOA and present performance data taken to date.

Subjects: INTERCONTINENTAL BALLISTIC MISSILES (ICBM), SILICON OSCILLATING ACCELEROMETERS (SOA), VIBRATING BEAM ACCELEROMETERS, MICROELECTROMECHANICAL SYSTEM (MEMS)

Houston, K.M.; McGaffigan, D.P.

Spectrum Analysis Techniques for Personnel Detection Using Seismic Sensors

MSS Specialty Group on Acoustic and Seismic Sensing. Held in Laurel, MD, 09/23/2002 to 09/26/2002. Sponsored by: IRIA. (Draper Report no. P-4051)

Abstract: There is a general need for improved detection range and false alarm performance for seismic sensors used for personnel detection. In this paper, we describe a novel footstep detection algorithm that was developed and run on seismic footstep data collected at the Aberdeen Proving Ground in December 2000. The initial focus was an assessment of achievable detection range. The conventional approach to footstep detection is to detect transients corresponding to individual footfalls. We feel this is an error-prone approach. Because many real-world signals unrelated to human locomotion look like transients, transient-based footstep detection will inevitably either suffer from high false alarm rates or will be insensitive. Instead, we examined the use of spectrum analysis on envelope-detected seismic signals and have found the general method to be quite promising, not only for detection, but also for discrimination against other types of seismic sources. In particular, gait patterns and their corresponding signatures may help discriminate between human intruders and animals. In the APG data set, mean detection ranges of 64 meters (at Pd = 50%) were observed for normal walking, significantly improving on ranges previously reported. For running, mean detection ranges of 84 meters were observed. However, stealthy walking (creeping) remains a considerable problem. Even at short ranges (10 meters), in some cases the detection rate was less than 50%. In future efforts, additional data sets for a range of geologic and environmental conditions should be acquired and analyzed. Improvements to the detection algorithms are possible, including estimation of direction of travel and the number of intruders.

Subjects: SPECTRUM ANALYSIS, SEISMIC SENSORS

Jackson, M.; Straube, T.; Fill, T.; Nemeth, S.

Onboard Determination of Vehicle Glide Cabability for Shuttle Abort Flight Management (SAFM)

Core Technologies for Space Systems. Held in Colorado Springs, CO, 11/19/2002 to 11/21/2002. Sponsored by: IEEE/AAS/AIAA. (Draper Report no. P-4050)

Abstract: An overview of the glided flight portion of the Shuttle Abort Flight Manager (SAFM) algorithm is presented. The algorithm determines Shuttle glide capability and continuously updates assessments of candidate runways during powered ascent as well as glided flight. SAFM requirements and cockpit displays are discussed briefly to provide background for Glided Flight algorithm design considerations. Major algorithm features are discussed, including vehicle pullout state prediction, the use of energy/range corridors to determine the vehicle footprint, and the compensation of vehicle energy to account for phugoid motion. The techniques used to assign figures of merit to each runway are covered, as well as runway prioritization methods that consider runway facilities in order to make a final landing site recommendation during an abort. Finally, display histories for several abort scenarios are provided as examples of algorithm performance.

Subjects: SPACE SHUTTLES, GLIDE PATH SYSTEMS, ALGORITHMS

Kachmar, P.M.

Apollo and Space Shuttle On-Board Navigation Systems: Application of Kalman Filtering Techniques

Institute of Navigation Annual Meeting. 58th. Held in Albuquerque, NM, 06/24/2002 to 06/26/2002. Sponsored by: ION. (Draper Report no. P-3996A)

Abstract: The use of Kalman filtering techniques in the on-board navigation systems for the Apollo Command Module and the Apollo Lunar Excursion Module was an important factor in the overwhelming success of the Lunar Landing Program. The adaptation and evolution of these techniques for the Space Shuttle rendezvous and entry navigation systems have been an important factor in the continuing success of the Space Shuttle program. This paper will present an historical perspective of the development of the navigation system designs for both programs. The evolution of the navigation system concepts and designs from those used successfully in the Apollo Program, to the navigation system concepts and designs used successfully in the Space Shuttle program, will be presented. Navigation sensors, system architecture and system operations will be described for the on-orbit, rendezvous, and entry and landing mission phases in which the Kalman filter was used for spacecraft navigation. System considerations and system-level decisions, which influenced the structure and design of the navigation systems, will be discussed. A description of the key assumptions made in the formulation of the filters, which impacted system design and operation, will also be described. In addition, the impact of existing navigation-related technologies (e.g., sensors, processors) on system architecture and operations will be described.

Subjects: KALMAN FILTERING, APOLLO, SPACE SHUTTLES

Kim, E.S.; Kaazempur-Mofrad, M.R.; Borenstein, J.T.; Vacanti, J.P.; Kamm, R.D.

Design of a Single Capillary-Parenchymal Co-Culture Bioreactor

Materials Research Society (MRS) Symposium. Held in San Francisco, CA, 04/01/2002 to 04/05/2002. Sponsored by: MRS. (Draper Report no. P-4006)

Abstract: A bioreactor is designed and fabricated for the co-culture of endothelial and hepatic parenchymal cells. The device provides a structured environment mimicking the in viva characteristics of a single capillary and the adjacent tissue. The bioreactor consists of two cell-scale fluid channels separated by a biocompatible thin porous membrane made of self-assembling oligopeptide gel. Analytic and computational modeling techniques were used to investigate the fluid flow and mass transfer characteristics and aid in the design of the bioreactor. Study of co-cultured cells in this device will contribute to the development of tissue-engineered organs.

Subjects: TISSUE ENGINEERING, MICROELECTROMECHANICAL SYSTEM (MEMS)

Kim, E.S.; Kaazempur-Mofrad, M.R.; Borenstein, J.T.; Vacanti, J.P.; Kamm, R.D.

Design of a Single Capillary-Parenchymal Co-Culture Bioreactor

Biomedical Engineering Society Fall Meeting. Held in Houston, TX, 10/23/2002 to 10/26/2002. Sponsored by: BMES. (Draper Report no. P-4008)

Abstract: A bioreactor is designed and fabricated for the co-culture of endothelial and hepatic parenchymal cells. The device provides a structured environment mimicking the in vivo characteristics of a single capillary and the adjacent tissue. The bioreactor consists of two cell-scale fluid channels separated by a biocompatible thin porous membrane made of self-assembling oligopeptide gel. Analytic and computational modeling techniques were used to investigate the fluid flow and mass transfer characteristics and aid in design of the bioreactor. Study of co-cultured cells in this device will contribute to the development of tissue-engineered organs.

Subjects: BIOSENSORS, TISSUE ENGINEERING, MICROELECTROMECHANICAL SYSTEM (MEMS)

Kondoleon, A.S.; Moore, R.

Manufacturing Process Improvement for Long Life Gas Bearing Assemblies

Joint Navigation Conference (JNC). 27th. Held in Orlando, FL, 05/06/2002 to 05/09/2002. (Draper Report no. P-4007)

Abstract: Gas bearings wheels, which are used in high-performance inertial instruments, are required to run long hours with no degradation in performance. This requires that the plasma-spray process used to coat the piece parts of the gas bearings be well understood in order that the parts can be reproduced over long periods of time. The present spool and hemispherical wheels have beryllium bearing surfaces machined and lapped from a plasma-sprayed Al2O3 coating. This coating is hard and produces a wear-resistant surface. The property of this coating is dependent on a variety of parameters, such as feed rate of the powder, the temperature, and the pressure of the gases. The process, used at the only approved source of these components, is manually set and controlled, but little science is involved in what the settings should be. The ultimate worth of the coating is the performance of the wheels tested after final assembly. Examining just the manufacturing data from the piece parts does not provide insight into the worth of the parts. Detailed examination of the surfaces and cross sections can give insight into a proper and consistent coating, but only running wheels with stable performance will provide the final answer as to the worth of any process changes. This paper outlines the steps being taken by Draper Laboratory to develop a group of systems that will provide a continuing supply of piece parts for long life wheel assemblies based on understating the plasma spray coating process and the semi-automation of some critical finishing operations.

Subjects: GAS BEARING WHEEL, MANUFACTURING, PROCESSING

Krupadanam, A.S.; Annaswamy, A.M.; Mangoubi, R.S.

Multivariable Adaptive Control Design with Applications to Autonomous Helicopters

Journal of Guidance, Control, and Dynamics, Vol. 25, No. 5, September-October 2002, pp. 843-851. (Draper Report no. P-3964)

Abstract: Control of autonomous helicopters in the presence of environmental and system uncertainties is a challenging task. These uncertainties not only change the dynamics of the system, but the trim inputs themselves. A viable multivariable adaptive control methodology is proposed that is applicable for general maneuvers with arbitrary speeds and high-bandwidth requirements. The control design methodology achieves global stability and is tested on a high-fidelity simulation of a real-life autonomous helicopter. The results indicate a satisfactory tracking performance even as the speeds and bandwidth requirements are increased well beyond hover and as the parametric uncertainties were increased by about 20% of their nominal values.

Subjects: ADAPTIVE CONTROL SYSTEMS, HELICOPTERS, AUTONOMOUS VEHICLES

Malcos, M.

Six-Sigma Performance Excellence

North East Quality Council Conference. 54th. Held in Mystic, CT, 10/21/2002 to 10/25/2002. Sponsored by: NEQC/ASQ. (Draper Report no. P-4047)

Subjects: DESIGN PROCESS, QUALITY CONTROL, OPERATIONAL PROCEDURES

Marinis, T.F.; Soucy, J.W.

Aluminum Nitride Chip Carrier for Microelectromechanical Sensor Applications

Materials Research Society (MRS) Fall Meeting. Held in Boston, MA, 12/02/2002 to 12/06/2002. Sponsored by: MRS. (Draper Report no. P-4061)

Abstract: A commercially fabricated aluminum nitride chip carrier was evaluated for packaging various types of MEMS inertial sensors. They were successfully assembled and vacuum-sealed within A1N chip carriers and their pressures have remained stable for over 1 year. Aging tests were conducted under electrical bias at 85°C and 85% RH. The leakage currents were not as stable as those measured in alumina chip carriers and post-test inspection of the A1N parts revealed etching of the ceramic between conductors.

Subjects: CHIP CARRIERS, MICROELECTROMECHANICAL SYSTEM (MEMS), INERTIAL SENSORS

Martorana, R.T.

WASP - a High-g Survivable UAV

Unmanned Aerospace Vehicles, Systems, Technologies, & Operations. 1st. Held in Portsmouth, VA, 05/20/2002 to 05/22/2002. Sponsored by: AIAA. (Draper Report no. P-3997)

Abstract: WASP (Wide Area Surveillance Projectile) is a folded UAV (Unmanned Air Vehicle) that is deployed as cargo from a standard 155-mm artillery round, the M-483A. A unique load-mitigation approach protects the Flyer from the extreme gun-fire environments, enabling it to use the gun's energy rather than its own to get to a target very quickly for time-critical targets. The Program demonstrated in December 2000 that the Flyer could be packaged and has flight integrity. WASP will use the existing 155-mm infrastructure for handling, loading, and transportation, and will not require a special UAV platoon for launch or recovery since it is expendable. This "UAV-in-a-can" may also be used for multiple zero and low-g applications.

Subjects: WIDE AREA SURVEILLANCE PROJECTILE (WASP), UNMANNED AERIAL VEHICLES (UAV)

Mescher, M.J.; Vladimer, M.L.; Bernstein, J.J.

A Novel High-Speed Piezoelectric Deformable Varifocal Mirror for Optical Applications

International Conference on Microelectromechanical Systems (MEMS). 15th. Held in Las Vegas, NV, 01/20/2002 to 01/25/2002, pp. 511-515. Sponsored by: IEEE. (Draper Report no. P-3939)

Abstract: We describe the characteristics of a microelectromechanical deformable optical component: a parabolic focusing mirror having a focal length that is controlled by piezoelectric actuation of thin-film PZT. Devices of two different sizes were tested and have resonant frequencies in the low MHz range, nominal focal lengths between 1500 and 2000 microns and numerical apertures of approximately 0.10 and 0.05. Tuning ranges of several hundred microns have been demonstrated. Finite-element modeling is described and compared to measured results. The equations required for device scaling are provided to show some of the trade-offs that can be made between aperture size, mechanical bandwidth, and focal length tuning range.

Subjects: MICROMIRRORS, PIEZOELECTRICITY, LEAD ZIRCONATE TITANATE (PZT)

Mettler, B.; Dever, C.; Feron, E.

Identification Modeling, Flying Qualities, and Dynamic Scaling of Miniature Rotorcraft

Challenges in Dynamics, System Identification, Control and Handling Qualities for Land, Air, Sea. Held in Berlin, Germany, 05/13/2002 to 05/15/2002. Sponsored by: NATO RTO. (Draper Report no. P-4019)

Abstract: In this paper, we present a parameterized linear model developed for the system identification of a Yamaha R-50 helicopter (10-ft rotor diameter) and applied to both the R-50 and a smaller, more agile X-Cell .60 helicopter (5 ft rotor diameter). Using this model, we derive flying qualities metrics as functions of physical characteristics, showing the influence of key system parameters. Based on this framework, we determine the effects of rotorcraft scale on flying qualities and performance characteristics. Finally, we summarize the results, emphasizing the features that are characteristic to small-scale rotorcraft, and providing a basis for the definition of operational characteristics for this class of vehicles.

Subjects: ROTORCRAFT AIRCRAFT, HELICOPTERS, IDENTIFICATION SYSTEMS

Miotto, P.

GN&C Autocode Procedures for Simulink Embedded Coder

Modeling and Simulation Technologies. Held in Monterey, CA, 08/05/2002 to 08/08/2002. Sponsored by: AIAA. (Draper Report no. P-4033)

Subjects: GUIDANCE NAVIGATION AND CONTROL (GN&C), SIMULINK, CODE GENERATION

Nervegna, M.; Ricard, M.; Keegan, M.

An Efficient Mapping System for Next-Generation Navy UUVs

International Symposium on Unmanned Systems. Held in Orlando, FL, 07/09/2002 to 07/11/2002. Sponsored by: AUVSI. (Draper Report no. P-3971)

Abstract: As part of the Future Naval Capabilities effort, The Charles Stark Draper Laboratory, The Naval Undersea Warfare Center, Division Newport and Northrop Grumman Corporation are working to perform a Maritime Reconnaissance Demonstration (MRD) with an Unmanned Undersea Vehicle (UUV). The concept of operations requires that the UUV be