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At least 523 records · Page 29

All sources NASA NTRS DOE OSTI

NASA NTRS1974

A strapdown laser gyro navigator

A broad spectrum of commercial and military vehicles employ some form of inertial measurement equipment. In general this equipment has a special purpose in that it was tailored for each specific application thereby resulting in high installation and maintenance costs. Recently the emphasis has been directed toward developing low cost building blocks from which the desired inertial functions can be derived. This paper describes a National Aeronautics and Space Administration (NASA) program that combines inertial system sensor and computational advances into a flight demonstration configuration. Specifically, an inertial navigation system employing strapdown laser gyro angular rate sensors and a miniature, modular digital flight computer is described. The objective of this program is to demonstrate, via flight test evaluation, the capabilities of the advanced sensor and computer as they apply to future low cost, high reliability inertial system applications.

Garret, H.↗

NASA NTRS2011

System for detecting and estimating concentrations of gas or liquid analytes

A sensor system for detecting and estimating concentrations of various gas or liquid analytes. In an embodiment, the resistances of a set of sensors are measured to provide a set of responses over time where the resistances are indicative of gas or liquid sorption, depending upon the sensors. A concentration vector for the analytes is estimated by satisfying a criterion of goodness using the set of responses. Other embodiments are described and claimed.

Homer, Margie L.↗

NASA NTRS1990

Developing a self-diagnostic system for piezoelectric sensors

Measurement techniques for developing a self-diagnostic system for piezoelectric sensors are presented. The self-diagnostic system uses two types of measurement techniques based on passive and active evaluation of the piezoelectric element. Both hard and soft failures can be detected by this system. Hard failures such as loss of sensor signal and change in sensor output resistance are determined by monitoring the sensor's output resistance, voltage or current. These are passive measurements of the sensor's output condition. Soft failures include changes in sensor calibration and mounting conditions. Soft failures are detected by measuring structural/electrical impedance of the piezoelectric sensor. Active measurement techniques are used to calculate changes in piezoelectric element properties related to soft failures. This paper describes the general operating principles of a self-diagnostic system and discusses the design of an active/passive measurement technique required for this system to function. Experimental results using two types of piezoelectric accelerometers are presented.

Flanagan, Patrick M.↗

NASA NTRS1993

On Machine Capacitance Dimensional and Surface Profile Measurement System

A program was awarded under the Air Force Machine Tool Sensor Improvements Program Research and Development Announcement to develop and demonstrate the use of a Capacitance Sensor System including Capacitive Non-Contact Analog Probe and a Capacitive Array Dimensional Measurement System to check the dimensions of complex shapes and contours on a machine tool or in an automated inspection cell. The manufacturing of complex shapes and contours and the subsequent verification of those manufactured shapes is fundamental and widespread throughout industry. The critical profile of a gear tooth; the overall shape of a graphite EDM electrode; the contour of a turbine blade in a jet engine; and countless other components in varied applications possess complex shapes that require detailed and complex inspection procedures. Current inspection methods for complex shapes and contours are expensive, time-consuming, and labor intensive.

Resnick, Ralph↗

NASA NTRS1988

Space vehicle glow and its impact on spacecraft systems

Spacecraft glow poses a contamination threat to low orbital altitude optical sensor systems. The complexity of the phenomena entails a multifaceted approach to system design for vehicle glow minimization. In the case of Space Shuttle cloud glow, which involves line and band emission, filtering and careful optical sensor wavelength selection may also prove useful; Space Shuttle thruster glow mitigation entails the limitation of thruster firings during sensor operations. Careful selection of instrument baffle materials and coatings, as well as control of surface temperatures, are recommended as ways of limiting glow impact for instruments directed in the direction of vehicle movement.

Garrett, H. B.↗

NASA NTRS1977

Multispectral system analysis through modeling and simulation

The design and development of multispectral remote sensor systems and associated information extraction techniques should be optimized under the physical and economic constraints encountered and yet be effective over a wide range of scene and environmental conditions. Direct measurement of the full range of conditions to be encountered can be difficult, time consuming, and costly. Simulation of multispectral data by modeling scene, atmosphere, sensor, and data classifier characteristics is set forth as a viable alternative, particularly when coupled with limited sets of empirical measurements. A multispectral system modeling capability is described. Use of the model is illustrated for several applications - interpretation of remotely sensed data from agricultural and forest scenes, evaluating atmospheric effects in LANDSAT data, examining system design and operational configuration, and development of information extraction techniques.

Malila, W. A.↗

NASA NTRS1977

Multispectral system analysis through modeling and simulation

The design and development of multispectral remote sensor systems and associated information extraction techniques should be optimized under the physical and economic constraints encountered and yet be effective over a wide range of scene and environmental conditions. Direct measurement of the full range of conditions to be encountered can be difficult, time consuming, and costly. Simulation of multispectral data by modeling scene, atmosphere, sensor, and data classifier characteristics is set forth as a viable alternative, particularly when coupled with limited sets of empirical measurements. A multispectral system modeling capability is described. Use of the model is illustrated for several applications - interpretation of remotely sensed data from agricultural and forest scenes, evaluating atmospheric effects in Landsat data, examining system design and operational configuration, and development of information extraction techniques.

Malila, W. A.↗

NASA NTRS1978

Improvements and modifications to the NASA microwave signature acquisition system

A user oriented description of the modified and upgraded Microwave Signature Acquisition System is provided. The present configuration of the sensor system and its operating characteristics are documented and a step-by-step operating procedure provides instruction for mounting the antenna truss assembly, readying the system for data acquisition, and for controlling the system during the data collection sequence. The resulting data products are also identified.

Jean, B. R.↗

NASA NTRS2000

Education, outreach and the future of remote sensing in human health

The human health community has been slow to adopt remote sensing technology for research, surveillance, or control activities. This chapter presents a brief history of the National Aeronautics and Space Administration's experiences in the use of remotely sensed data for health applications, and explores some of the obstacles, both real and perceived, that have slowed the transfer of this technology to the health community. These obstacles include the lack of awareness, which must be overcome through outreach and proper training in remote sensing, and inadequate spatial, spectral and temporal data resolutions, which are being addressed as new sensor systems are launched and currently overlooked (and underutilized) sensors are newly discovered by the health community. A basic training outline is presented, along with general considerations for selecting training candidates. The chapter concludes with a brief discussion of some current and future sensors that show promise for health applications.

Review, Tutorial↗

NASA NTRS1975

Low-cost data analysis systems for processing multispectral scanner data

A research-oriented data analysis system was developed which is used for evaluating complex remote sensor systems and for development of techniques for application of remotely sensed data. Some modular hardware components were developed which may be added to one's existing facilities to establish a low-cost data analysis system for processing multispectral scanner data. Software modules which are compatible with small general purpose digital computers process and analyze remote sensor data, and convert it to information needed by users. The software modules are written in FORTRAN IV language for ease of transfer to other computer systems. The basic hardware and software system requirements are defined for some low-cost data analysis systems consisting of an image display system, a small general purpose digital computer, and an output recording device. The hardware modules consist of: a LANDSAT MSS data reformatting program; a series of spectral pattern recognition programs required to generate surface classification maps and tabular information; programs to convert computer generated maps from image space to a geographically referenced base; programs to extract data and irregularly shaped areas and to produce thematic maps of the designated areas; and programs to tabulate acreages of selected classification categories. Some off-the-shelf, inexpensive digital image display systems are described.

Whitley, S. L.↗

NASA NTRS2011

Wireless tamper detection sensor and sensing system

A wireless tamper detection sensor is defined by a perforated electrical conductor. The conductor is shaped to form a geometric pattern between first and second ends thereof such that the conductor defines an open-circuit that can store and transfer electrical and magnetic energy. The conductor resonates in the presence of a time-varying magnetic field to generate a harmonic response. The harmonic response changes when the conductor experiences a change in its geometric pattern due to severing of the conductor along at least a portion of the perforations. A magnetic field response recorder is used to wirelessly transmit the time-varying magnetic field and wirelessly detecting the conductor's harmonic response.

Woodard, Stanley E.↗

NASA NTRS2003

Estimating Uncertainty in GPCP and TRMM Multi-Satellite Precipitation Estimates

One of the high-priority problems in satellite precipitation estimation is developing algorithms for estimating the errors in precipitation retrievals by individual sensors and subsequent multi-satellite combinations. Classically, we distinguish between "random" and "bias" errors, which do and do not, respectively average to zero over a "big enough" time/space sample. The current operational GPCP and TRMM multi-satellite algorithms are nearly unique in estimating random error for the monthly precipitation estimates from individual sensor systems (including gauge), following Huffman, and then making multi-sensor combinations. No routinely operational global precipitation produces estimates of bias error. Subsequently, a similar scheme has been followed to provide random error estimates for the Multi-satellite Precipitation Analysis (MPA) being computed in real time and after real time for TRMM. The Huffman algorithm for random error is briefly reviewed, including a discussion of the limitations imposed on the algorithm by standard monthly precipitation data sets. Starting from a very simple theoretical treatment of the histogram of precipitation samples in a month, an equation is developed that depends on the estimated average precipitation rate for the month, the number of samples in the month, and two constants. The constants are set separately for each source of precipitation estimate (such as "raingauge") by calibration at selected ground sites. We discuss recent work validating the random error estimates to highlight the successes and limitations of this first-generation approach. We then consider what information is needed from the individual sensor algorithms to facilitate additional accuracy in the estimation of random errors across the time/space span of climate regimes which a global estimation system must handle. In addition, the thorny issue of estimating bias is raised. Finally, the role of error estimates (and the qualitative errors!) in creating combinations of precipitation estimates from different individual sensors is discussed. This issue is particularly important when fine scales in space and time are being considered, say the 0.25 x 0.25-deg 3-hourly estimates in the MPA.

Huffman, G. J.↗

NASA NTRS1988

Optical fiber sensors and signal processing for intelligent structure monitoring

The analytic and experimental performance of optical fiber sensors for the control of vibration of large aerospace and other structures are investigated. In particular, model domain optical fiber sensor systems, are being studied due to their apparent potential as distributed, low mass sensors of vibration over appropriate ranges of both low frequency and low amplitude displacements. Progress during the past three months is outlined. Progress since September is divided into work in the areas of experimental hardware development, analytical analysis, control design and sensor development. During the next six months, tests of a prototype closed-loop control system for a beam are planned which will demonstrate the solution of several optical fiber instrumentation device problems, the performance of the control system theory which incorporates the model of the modal domain sensor, and the potential for distributed control which this sensor approach offers.

Rogowski, Robert↗

NASA NTRS2015

Analysis of UAS DAA Surveillance in Fast-Time Simulations without DAA Mitigation

Realization of the expected proliferation of Unmanned Aircraft System (UAS) operations in the National Airspace System (NAS) depends on the development and validation of performance standards for UAS Detect and Avoid (DAA) Systems. The RTCA Special Committee 228 is charged with leading the development of draft Minimum Operational Performance Standards (MOPS) for UAS DAA Systems. NASA, as a participating member of RTCA SC-228 is committed to supporting the development and validation of draft requirements for DAA surveillance system performance. A recent study conducted using NASA's ACES (Airspace Concept Evaluation System) simulation capability begins to address questions surrounding the development of draft MOPS for DAA surveillance systems. ACES simulations were conducted to study the performance of sensor systems proposed by the SC-228 DAA Surveillance sub-group. Analysis included but was not limited to: 1) number of intruders (both IFR and VFR) detected by all sensors as a function of UAS flight time, 2) number of intruders (both IFR and VFR) detected by radar alone as a function of UAS flight time, and 3) number of VFR intruders detected by all sensors as a function of UAS flight time. The results will be used by SC-228 to inform decisions about the surveillance standards of UAS DAA systems and future requirements development and validation efforts.

unmanned aircraft systems↗

NASA NTRS2010

Micrometeoroid and Lunar Secondary Ejecta Flux Measurements: Comparison of Three Acoustic Systems

This report examines the inherent capability of three large-area acoustic sensor systems and their applicability for micrometeoroids (MM) and lunar secondary ejecta (SE) detection and characterization for future lunar exploration activities. Discussion is limited to instruments that can be fabricated and deployed with low resource requirements. Previously deployed impact detection probes typically have instrumented capture areas less than 0.2 square meters. Since the particle flux decreases rapidly with increased particle size, such small-area sensors rarely encounter particles in the size range above 50 microns, and even their sampling the population above 10 microns is typically limited. Characterizing the sparse dust population in the size range above 50 microns requires a very large-area capture instrument. However it is also important that such an instrument simultaneously measures the population of the smaller particles, so as to provide a complete instantaneous snapshot of the population. For lunar or planetary surface studies, the system constraints are significant. The instrument must be as large as possible to sample the population of the largest MM. This is needed to reliably assess the particle impact risks and to develop cost-effective shielding designs for habitats, astronauts, and critical instrument. The instrument should also have very high sensitivity to measure the flux of small and slow SE particles. is the SE environment is currently poorly characterized, and possess a contamination risk to machinery and personnel involved in exploration. Deployment also requires that the instrument add very little additional mass to the spacecraft. Three acoustic systems are being explored for this application.

Corsaro, R. D.↗

NASA NTRS2022

Spatial Grid-Based Object Localization from A Single Passive Sensor: A Deep Learning-Integrated Approach

Ongoing efforts at NASA’s Langley Research Center have produced a single passive sensor system for detecting ground objects and pinpointing their real-world location to a desired level of precision. The Langley center serves as a test range for unmanned aerial systems (UAS) and real-time knowledge about the location of people on campus is needed to inform least-risk UAS flight operations. The proposed system provides this knowledge through a camera combined with a convolutional neural network and an algorithm that projects an imaginary grid of square cells from the ground plane onto the perspective view of the camera. The position of detected objects on the camera’s projected grid determines their location in the real-world. The imaginary grid is easily mapped to a universal coordinate system, such as longitude and latitude, to provide both relative and absolute positional information of the detected objects. This simple system is shown to be accurate and effective, with decisive advantages over alternative multi-sensor and active sensor approaches. Extensions to the system are described to allow adaptation to a variety of other use cases.

object localization↗

DOE OSTI2020

Ultra-Low SWaP CO 2 Sensing for Demand Control Ventilation (Final Report)

In this project PARC and Energy ETC aimed to develop an ultra-low cost, size, weight, and power (SWaP) printed CO 2 sensor system for occupancy detection to enable Demand Control Ventilation (DCV) on a per-room basis. The CO 2 sensor technology is based on the temperature variation when CO 2 reversibly physisorbs to a highly conductive and high surface area sorbent surface, and is compatible with integration with PARC innovations in printed sensors and flexible electronics, for which PARC is a globally leading research center. The printed CO 2 sensor itself is designed to be compatible with PARC’s “peel-and-stick” platform of ultra-low power, low-cost, distributed sensors, and to facilitate real-time DCV based on overall indoor air quality (IAQ). Previously, PARC has developed flexible hybrid electronics (FHE) compatible materials to measure humidity, temperature, light, strain, and gases such as carbon monoxide, methane, ammonia, and hydrogen sulfide. Through this project, PARC developed FHE-compatible materials to measure CO 2 . Thus, with one <$15 FHE “peel-and-stick” based sensor node, a building management system (BMS) will be able to capture a complete picture of the indoor environment. This includes IAQ, light, temperature, and other comfort factors that impact building operations. Combined with optimized DCV, this low-cost sensor capability can be a key enabler of annual primary energy savings of ~ 0.3-0.4 Quad in commercial buildings while ensuring healthy IAQ. Energy ETC is a leader in supplier-agnostic BMS deployments and will design the commissioning and deployment procedures to maximize system interoperability.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

NASA NTRS1989

A temperature and pressure controlled calibration system for pressure sensors

A data acquisition and experiment control system capable of simulating temperatures from -184 to +220 C and pressures either absolute or differential from 0 to 344.74 kPa is developed to characterize silicon pressure sensor response to temperature and pressure. System software is described that includes sensor data acquisition, algorithms for numerically derived thermal offset and sensitivity correction, and operation of the environmental chamber and pressure standard. This system is shown to be capable of computer interfaced cryogenic testing to within 1 C and 34.47 Pa of single channel or multiplexed arrays of silicon pressure sensors.

Chapman, John J.↗