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At least 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Moving Through Time: The Utility of a Temporal Metric for Vehicular Control

Recent work on time-to-contact (TTC) and time-to-passage (TTP) estimation have revealed conflicting evidence. On the one hand, when tau information is available, observers often fail to use it properly. For instance, absolute size of the object, rotation, and contrast all interfere with estimation accuracy. That is, the visual system often is unable to isolate tau. On the other hand, judgments are remarkably robust when invariant information is no longer available. Observers seem to adjust to many disturbances. This symposium intends to stimulate a discussion of recent findings within visual and auditory TTC paradigms. Alternative concepts that are able to accommodate these findings should be entertained and, if found valid, incorporated into the classic theory of temporal-range estimation.

Kaiser, Mary K.↗
NASA NTRS2001

A Novel Telometric Metric for In-Situ Measurement of Intrauterine Pressure (IUP) in Pregnant and Parturient Rats

During labor and birth, considerable forces exerted on fetuses help instigate certain adaptive postpartum responses (viz., breathing and suckling). To make precise, reliable measures of the forces experienced by rat fetuses during parturition, we developed a novel method for measuring intrauterine pressure (IUP) in late pregnant rats. A small (1.25 x 4cm) telemetric blood pressure sensor is fitted within a fluid-filled balloon, similar in size to a full term rat fetus. The balloon is surgically implanted in the uterus on Gestational Day 19 of the rats' 22-day pregnancy. During birth, dams are able to deliver their pups and the balloon. IUP arsenals are recorded during labor (G22 or 23) and birth. Data derived from a group of implanted rats indicated that pressures on the balloon increased across the period of birth, reaching 18 mmHg during labor, 25 mmHg during pup births and 39 mmHg just prior to delivery of the balloon. These data are within the range reported for conventional IUP measurement techniques. Dams are simultaneously videotaped, enabling us to analyze behavioral expressions of labor contractions and to integrate in-situ and behavioral findings.

Baer, Lisa A.↗
NASA NTRS2002

Structural Life and Reliability Metrics: Benchmarking and Verification of Probabilistic Life Prediction Codes

Over the past two decades there has been considerable effort by NASA Glenn and others to develop probabilistic codes to predict with reasonable engineering certainty the life and reliability of critical components in rotating machinery and, more specifically, in the rotating sections of airbreathing and rocket engines. These codes have, to a very limited extent, been verified with relatively small bench rig type specimens under uniaxial loading. Because of the small and very narrow database the acceptance of these codes within the aerospace community has been limited. An alternate approach to generating statistically significant data under complex loading and environments simulating aircraft and rocket engine conditions is to obtain, catalog and statistically analyze actual field data. End users of the engines, such as commercial airlines and the military, record and store operational and maintenance information. This presentation describes a cooperative program between the NASA GRC, United Airlines, USAF Wright Laboratory, U.S. Army Research Laboratory and Australian Aeronautical & Maritime Research Laboratory to obtain and analyze these airline data for selected components such as blades, disks and combustors. These airline data will be used to benchmark and compare existing life prediction codes.

Litt, Jonathan S.↗
NASA NTRS2005

Initial Development of a Metric to Describe the Level of Safety Associated with Piloting an Aircraft with Synthetic Vision Systems (SVS) Displays

Synthetic Vision Systems (SVS) displays provide pilots with a continuous view of terrain combined with integrated guidance symbology in an effort to increase situation awareness (SA) and decrease workload during operations in Instrument Meteorological Conditions (IMC). It is hypothesized that SVS displays can replicate the safety and operational flexibility of flight in Visual Meteorological Conditions (VMC), regardless of actual out-the-window (OTW) visibility or time of day. Significant progress has been made towards evolving SVS displays as well as demonstrating their ability to increase SA compared to conventional avionics in a variety of conditions. While a substantial amount of data has been accumulated demonstrating the capabilities of SVS displays, the ability of SVS to replicate the safety and operational flexibility of VMC flight performance in all visibility conditions is unknown to any specific degree. In order to more fully quantify the relationship of flight operations in IMC with SVS displays to conventional operations conducted in VMC, a fundamental comparison to current day general aviation (GA) flight instruments was warranted. Such a comparison could begin to establish the extent to which SVS display concepts are capable of maintaining an "equivalent level of safety" with the round dials they could one day replace, for both current and future operations. A combination of subjective and objective data measures were used to quantify the relationship between selected components of safety that are associated with flying an approach. Four information display methods ranging from a "round dials" baseline through a fully integrated SVS package that includes terrain, pathway based guidance, and a strategic navigation display, were investigated in this high fidelity simulation experiment. In addition, a broad spectrum of pilots, representative of the GA population, were employed for testing in an attempt to enable greater application of the results and determine if "equivalent levels of safety" are achievable through the incorporation of SVS technology regardless of a pilot's flight experience.

Bartolone, Anthony P.↗
NASA NTRS2005

INDUCTIVE SYSTEM HEALTH MONITORING WITH STATISTICAL METRICS

Model-based reasoning is a powerful method for performing system monitoring and diagnosis. Building models for model-based reasoning is often a difficult and time consuming process. The Inductive Monitoring System (IMS) software was developed to provide a technique to automatically produce health monitoring knowledge bases for systems that are either difficult to model (simulate) with a computer or which require computer models that are too complex to use for real time monitoring. IMS processes nominal data sets collected either directly from the system or from simulations to build a knowledge base that can be used to detect anomalous behavior in the system. Machine learning and data mining techniques are used to characterize typical system behavior by extracting general classes of nominal data from archived data sets. In particular, a clustering algorithm forms groups of nominal values for sets of related parameters. This establishes constraints on those parameter values that should hold during nominal operation. During monitoring, IMS provides a statistically weighted measure of the deviation of current system behavior from the established normal baseline. If the deviation increases beyond the expected level, an anomaly is suspected, prompting further investigation by an operator or automated system. IMS has shown potential to be an effective, low cost technique to produce system monitoring capability for a variety of applications. We describe the training and system health monitoring techniques of IMS. We also present the application of IMS to a data set from the Space Shuttle Columbia STS-107 flight. IMS was able to detect an anomaly in the launch telemetry shortly after a foam impact damaged Columbia's thermal protection system.

Iverson, David L.↗
NASA NTRS2004

Defining Exercise Performance Metrics for Flight Hardware Development

The space industry has prevailed over numerous design challenges in the spirit of exploration. Manned space flight entails creating products for use by humans and the Johnson Space Center has pioneered this effort as NASA's center for manned space flight. NASA Astronauts use a suite of flight exercise hardware to maintain strength for extravehicular activities and to minimize losses in muscle mass and bone mineral density. With a cycle ergometer, treadmill, and the Resistive Exercise Device available on the International Space Station (ISS), the Space Medicine community aspires to reproduce physical loading schemes that match exercise performance in Earth s gravity. The resistive exercise device presents the greatest challenge with the duty of accommodating 20 different exercises and many variations on the core set of exercises. This paper presents a methodology for capturing engineering parameters that can quantify proper resistive exercise performance techniques. For each specified exercise, the method provides engineering parameters on hand spacing, foot spacing, and positions of the point of load application at the starting point, midpoint, and end point of the exercise. As humans vary in height and fitness levels, the methodology presents values as ranges. In addition, this method shows engineers the proper load application regions on the human body. The methodology applies to resistive exercise in general and is in use for the current development of a Resistive Exercise Device. Exercise hardware systems must remain available for use and conducive to proper exercise performance as a contributor to mission success. The astronauts depend on exercise hardware to support extended stays aboard the ISS. Future plans towards exploration of Mars and beyond acknowledge the necessity of exercise. Continuous improvement in technology and our understanding of human health maintenance in space will allow us to support the exploration of Mars and the future of space exploration.

Beyene, Nahon M.↗
NASA NTRS1994

Contrasting Target, Stray-Light, and Other Performance Metrics for MISR

The Multi-angle Imaging Spectrometer (MISR) is an Earth-observing sensor to be flown as part of the Earth Observing System (EOS) in 1998. The radiometric and spectral calibration of the nine cameras which compose this instrument will be done using targets which are uniform in space and in angle, unpolarized, and lacking in absorption lines. A calibration uncertainty will also be determined for this configuration. This allows one to estimate the accuracy of measured radiances, assuming the scene is likewise featureless with respect to these parameters. In addition to these calibrations, the MISR engineering team will be responsible for verification of certain performance specifications which assure data products can be produced for a range of target types.

Multi-angle Imaging Spectrometer MISR Earth Observ↗
NASA NTRS2008

3D Air Quality and the Clean Air Interstate Rule: Lagrangian Sampling of CMAQ Model Results to Aid Regional Accountability Metrics

The Clean Air Interstate Rule (CAIR) is expected to reduce transport of air pollutants (e.g. fine sulfate particles) in nonattainment areas in the Eastern United States. CAIR highlights the need for an integrated air quality observational and modeling system to understand sulfate as it moves in multiple dimensions, both spatially and temporally. Here, we demonstrate how results from an air quality model can be combined with a 3d monitoring network to provide decision makers with a tool to help quantify the impact of CAIR reductions in SO2 emissions on regional transport contributions to sulfate concentrations at surface monitors in the Baltimore, MD area, and help improve decision making for strategic implementation plans (SIPs). We sample results from the Community Multiscale Air Quality (CMAQ) model using ensemble back trajectories computed with the NASA Langley Research Center trajectory model to provide Lagrangian time series and vertical profile information, that can be compared with NASA satellite (MODIS), EPA surface, and lidar measurements. Results are used to assess the regional transport contribution to surface SO4 measurements in the Baltimore MSA, and to characterize the dominant source regions for low, medium, and high SO4 episodes.

Fairlie, T. D.↗
NASA NTRS2009

[A Handling Qualities Metric for Damaged Aircraft]

In recent flight tests of F-15 Intelligent Flight Control System (IFCS), software simulated aircraft control surface failures were inserted to evaluate the IFCS adaptive systems. The failure commanded the left stabilator to a fixed position. The adaptive system uses a neural network that is designed to change control law gains, in the event of damage (real or simulated), that allows the aircraft to fly as it had before the damage. The performance of the adaptive system was assessed in terms of its ability to re-establish good onboard model tracking and its ability to decouple roll and pitch response.

Cogan, Bruce↗
NASA NTRS2006

Telemetry Metrics: Monitoring Data Quality in the Spacecraft Ground Data System

During the launch of Mars Odyssey, ground data system (GDS) engineers experienced a glitch in the ground data system that caused us to re-evaluate how we looked at spacecraft telemetry, particularly during the spacecraft development period and for critical spacecraft events in flight. Spacecraft telemetry told the subsystem and instrument engineers about the health and status of the spacecraft, but there was surprisingly little information about how well the ground data system was doing in getting information from the spacecraft to the engineers.The problem for the Mars Odyssey launch was with a single channel not updating as often as expected. Spacecraft engineers considered calling off the Launch but eventually decided that this particular channel did not provide information that was crucial for launch. It was only after the post launch acquisition of the Odyssey signal that ground data system engineers heard there had been a concern about the channel....

Mars↗
NASA NTRS2012

A Briefing on Metrics and Risks for Autonomous Decision-Making in Aerospace Applications

Significant technology advances will enable future aerospace systems to safely and reliably make decisions autonomously, or without human interaction. The decision-making may result in actions that enable an aircraft or spacecraft in an off-nominal state or with slightly degraded components to achieve mission performance and safety goals while reducing or avoiding damage to the aircraft or spacecraft. Some key technology enablers for autonomous decision-making include: a continuous state awareness through the maturation of the prognostics health management field, novel sensor development, and the considerable gains made in computation power and data processing bandwidth versus system size. Sophisticated algorithms and physics based models coupled with these technological advances allow reliable assessment of a system, subsystem, or components. Decisions that balance mission objectives and constraints with remaining useful life predictions can be made autonomously to maintain safety requirements, optimal performance, and ensure mission objectives. This autonomous approach to decision-making will come with new risks and benefits, some of which will be examined in this paper. To start, an account of previous work to categorize or quantify autonomy in aerospace systems will be presented. In addition, a survey of perceived risks in autonomous decision-making in the context of piloted aircraft and remotely piloted or completely autonomous unmanned autonomous systems (UAS) will be presented based on interviews that were conducted with individuals from industry, academia, and government.

Frost, Susan↗
NASA NTRS2012

Geometry-Based Observability Metric

The Satellite Servicing Capabilities Office (SSCO) is currently developing and testing Goddard s Natural Feature Image Recognition (GNFIR) software for autonomous rendezvous and docking missions. GNFIR has flight heritage and is still being developed and tailored for future missions with non-cooperative targets: (1) DEXTRE Pointing Package System on the International Space Station, (2) Relative Navigation System (RNS) on the Space Shuttle for the fourth Hubble Servicing Mission.

Eaton, Colin↗
NASA NTRS2014

Prototype and Metrics for Data Processing Chain Components of IPM

This presentation lays out the evolution of the Intelligent Payload Module (IPM) vision given that the HyspIRI mission has been delayed. It shows that there has been a focus on airborne vehcile and unmanned aerial systems to further develop the IPM functionality. This of course does not preclude use of the IPM for space missions but provides alternate paths to continue the concept of improved onboard processing for low latency users of science data products.

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