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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Flight data acquisition methodology for validation of passive ranging algorithms for obstacle avoidance

The automation of low-altitude rotorcraft flight depends on the ability to detect, locate, and navigate around obstacles lying in the rotorcraft's intended flightpath. Computer vision techniques provide a passive method of obstacle detection and range estimation, for obstacle avoidance. Several algorithms based on computer vision methods have been developed for this purpose using laboratory data; however, further development and validation of candidate algorithms require data collected from rotorcraft flight. A data base containing low-altitude imagery augmented with the rotorcraft and sensor parameters required for passive range estimation is not readily available. Here, the emphasis is on the methodology used to develop such a data base from flight-test data consisting of imagery, rotorcraft and sensor parameters, and ground-truth range measurements. As part of the data preparation, a technique for obtaining the sensor calibration parameters is described. The data base will enable the further development of algorithms for computer vision-based obstacle detection and passive range estimation, as well as provide a benchmark for verification of range estimates against ground-truth measurements.

Smith, Phillip N.↗
NASA NTRS1997

Analysis of Technology for Compact Coherent Lidar

In view of the recent advances in the area of solid state and semiconductor lasers has created new possibilities for the development of compact and reliable coherent lidars for a wide range of applications. These applications include: Automated Rendezvous and Capture, wind shear and clear air turbulence detection, aircraft wake vortex detection, and automobile collision avoidance. The work performed by the UAH personnel under this Delivery Order, concentrated on design and analyses of a compact coherent lidar system capable of measuring range and velocity of hard targets, and providing air mass velocity data. The following is the scope of this work. a. Investigate various laser sources and optical signal detection configurations in support of a compact and lightweight coherent laser radar to be developed for precision range and velocity measurements of hard and fuzzy targets. Through interaction with MSFC engineers, the most suitable laser source and signal detection technique that can provide a reliable compact and lightweight laser radar design will be selected. b. Analyze and specify the coherent laser radar system configuration and assist with its optical and electronic design efforts. Develop a system design including its optical layout design. Specify all optical components and provide the general requirements of the electronic subsystems including laser beam modulator and demodulator drivers, detector electronic interface, and the signal processor. c. Perform a thorough performance analysis to predict the system measurement range and accuracy. This analysis will utilize various coherent laser radar sensitivity formulations and different target models.

Amzajerdian, Farzin↗
NASA NTRS2014

Middle Man Concept for In-Orbit Collision Risks Mitigation, CAESAR and CARA Examples

This paper describes the conjunction analysis which has to be performed using data provided by JSpOC. This description not only demonstrates that Collision Avoidance is a 2- step process (close approach detection followed by risk evaluation for collision avoidance decision) but also leads to the conclusion that there is a need for a Middle Man role. After describing the Middle Man concept, this paper introduces two examples with their similarities and particularities: the American civil space effort delivered by the NASA CARA team (Conjunction Assessment Risk Analysis) and the French response CAESAR (Conjunction Assessment and Evaluation Service: Alerts and Recommendations). For both, statistics are presented and feedbacks discussed. All together, around 80 satellites are served by CARA and/or CAESAR. Both processes regularly evolve in order either to follow JSpOC upgrades or to improve analysis according to experience acquired during the past years.

conjunction↗
NASA NTRS2017

Unmanned Aircraft Systems (UAS) Integration in the National Airspace System (NAS) Project: Advanced Collision Avoidance System for UAS (ACAS Xu) Interoperability White Paper Presentation

The Phase 1 DAA Minimum Operational Performance Standards (MOPS) provided requirements for two classes of DAA equipment: equipment Class 1 contains the basic DAA equipment required to assist a pilot in remaining well clear, while equipment Class 2 integrates the Traffic Alert and Collision Avoidance (TCAS) II system. Thus, the Class 1 system provides RWC functionality only, while the Class 2 system is intended to provide both RWC and Collision Avoidance (CA) functionality, in compliance with the Minimum Aviation System Performance (MASPS) for the Interoperability of Airborne Collision Avoidance Systems. The FAAs TCAS Program Office is currently developing Airborne Collision Avoidance System X (ACAS X) to support the objectives of the Federal Aviation Administrations (FAA) Next Generation Air Transportation System Program (NextGen). ACAS X has a suite of variants with a common underlying design that are intended to be optimized for their intended airframes and operations. ACAS Xu being is designed for UAS and allows for new surveillance technologies and tailored logic for platforms with different performance characteristics. In addition to Collision Avoidance (CA) alerting and guidance, ACAS Xu is being tuned to provide RWC alerting and guidance in compliance with the SC 228 DAA MOPS. With a single logic performing both RWC and CA functions, ACAS Xu will provide industry with an integrated DAA solution that addresses many of the interoperability shortcomings of Phase I systems. While the MOPS for ACAS Xu will specify an integrated DAA system, it will need to show compliance with the RWC alerting thresholds and alerting requirements defined in the DAA Phase 2 MOPS. Further, some functional components of the ACAS Xu system such as the remote pilots displayed guidance might be mostly references to the corresponding requirements in the DAA MOPS. To provide a seamless, integrated, RWC-CA system to assist the pilot in remaining well clear and avoiding collisions, several issues need to be addressed within the Phase 2 SC-228 DAA efforts. Interoperability of the RWC and CA alerting and guidance, and ensuring pilot comprehension, compliance and performance, will be a primary research area.

detect and avoid↗
NASA NTRSDate not supplied

Hazard Perception and Avoidance (HPA) Overview

This short presentation is intended to provide RTCA Special Committee 147 (SC-147) members an overview of Advanced Air Mobility's Hazard Perception and Avoidance (HPA) technical area. This talk includes background on HPA's high-level objectives, as well as quick view of their upcoming simulation and flight test work. The presentation ends with plans for how HPA will coordinate with RTCA going forward.

automation↗
NASA NTRS2019

Unmanned Aircraft Systems (UAS) Integration in the National Airspace System (NAS) Project: ACAS Xu Engineering Analysis Results

This presentation provides an overview of the results from a two-part engineering analysis conducted as part of the Unmanned Aircraft Systems (UAS) Integration in the National Airspace System (NAS) Project. Part one of this analysis examined how to present resolution advisories (RAs) issued by Airborne Collision Avoidance System (ACAS) Xu, which can be in the vertical dimension, the horizontal dimension, or both (i.e., "blended"). The study varied the appearance of the alerting and the verbiage used in the aural alerts. Results revealed high acceptability ratings for the appearance of the RA guidance. Part two of the analysis assessed pilot acceptability of varying levels of automation in the collision avoidance (CA) task. Pilots experienced conditions in which ACAS Xu RAs were executed either manually or automatically (i.e., auto-Collision Avoidance). In some conditions the return to a previously filed course was also executed automatically (auto-Return to Course). Results indicated that improvements are needed to how the state of the automation is presented. Implications of these findings are also discussed.

Detect and Avoid↗
NASA NTRS2012

Cloud Screening and Quality Control Algorithm for Star Photometer Data: Assessment with Lidar Measurements and with All-sky Images

This paper presents the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. These algorithms are necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, delta Ae(lambda), and precipitable water vapor content, W, at nighttime. This cloud screening procedure consists of calculating moving averages of delta Ae() and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable Ae(lambda) and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16 N, 3.60 W, 680 ma.s.l.; South-East of Spain) for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.

data quality control algorithm↗
NASA NTRS1990

Analysis of aircraft performance during lateral maneuvering for microburst avoidance

Aircraft response to a severe and a moderate three-dimensional microburst model using nonlinear numerical simulations of a Boeing 737-100 is studied. The relative performance loss is compared for microburst escape procedures with and without lateral maneuvering. The results show that the hazards caused by the penetration of a microburst in the landing phase are attenuated if lateral escape maneuvers are applied in order to turn the aircraft away from the microburst core rather than flying straight through. If the lateral escape maneuver is initiated close to the microburst core, high bank angles tend to deteriorate aircraft performance. Lateral maneuvering is also found to reduce the advanced warning required to escape from microburst hazards but requires that information of the existence and location of the microburst is available (i.e., remote detection) in order to avoid an incorrect turn toward the microburst core.

Avila De Melo, Denise↗
NASA NTRSDate not supplied

UAS Pilot Performance Comparisons with Different Low Size, Weight and Power Sensor Ranges

The present study evaluated the performance of UAS pilots under four simulated low size, weight, and power (SwaP) sensor ranges: 1.5nmi, 2.0nmi, 2.5nmi, and 3.0nmi. Nine active-duty UAS pilots responded to scripted DAA conflicts against non-cooperative intruders while flying a simulated RQ-7 Shadow at varied speeds along a pre-filed flight path in Class E airspace. Findings revealed a linear effect of sensor range on alerting time and separation performance, with nearly every DAA well clear (DWC) violation and all Near Mid-Air Collision (NMAC) events occurring below 2.5nmi. Response time differences at these reduced ranges were negligible due to the high frequency of warning-level alerts that require an immediate response. Since caution alert duration was truncated to some degree by each tested declaration range, pilots were often unable to coordinate their avoidance maneuvers with ATC prior to their uploads. Nonetheless, the 2.5nmi range allowed minimum alerting times that were sufficient for acceptable pilot performance. These findings will inform DAA system requirements for UAS with alternative surveillance equipment and aircraft performance capabilities. Implications on DAA display and sensor requirements are discussed.

unmanned aircraft systems↗
NASA NTRS2020

UAS Pilot Performance Comparisons with Different Low Size, Weight and Power Sensor Ranges

The present study evaluated the performance of UAS pilots under four simulated low size, weight, and power (SwaP) sensor ranges: 1.5nmi, 2.0nmi, 2.5nmi, and 3.0nmi. Nine active-duty UAS pilots responded to scripted DAA conflicts against non-cooperative intruders while flying a simulated RQ-7 Shadow at varied speeds along a pre-filed flight path in Class E airspace. Findings revealed a linear effect of sensor range on alerting time and separation performance, with nearly every DAA well clear (DWC) violation and all Near Mid-Air Collision (NMAC) events occurring below 2.5nmi. Response time differences at these reduced ranges were negligible due to the high frequency of warning-level alerts that require an immediate response. Since caution alert duration was truncated to some degree by each tested declaration range, pilots were often unable to coordinate their avoidance maneuvers with ATC prior to their uploads. Nonetheless, the 2.5nmi range allowed minimum alerting times that were sufficient for acceptable pilot performance. These findings will inform DAA system requirements for UAS with alternative surveillance equipment and aircraft performance capabilities. Implications on DAA display and sensor requirements are discussed.

unmanned aircraft systems↗
NASA NTRSDate not supplied

UAS Pilot Performance Comparisons with Different Low Size, Weight and Power Sensor Ranges

The present study evaluated the performance of UAS pilots under four simulated low size, weight, and power (SwaP) sensor ranges: 1.5nmi, 2.0nmi, 2.5nmi, and 3.0nmi. Nine active-duty UAS pilots responded to scripted DAA conflicts against non-cooperative intruders while flying a simulated RQ-7 Shadow at varied speeds along a pre-filed flight path in Class E airspace. Findings revealed a linear effect of sensor range on alerting time and separation performance, with nearly every DAA well clear (DWC) violation and all Near Mid-Air Collision (NMAC) events occurring below 2.5nmi. Response time differences at these reduced ranges were negligible due to the high frequency of warning-level alerts that require an immediate response. Since caution alert duration was truncated to some degree by each tested declaration range, pilots were often unable to coordinate their avoidance maneuvers with ATC prior to their uploads. Nonetheless, the 2.5nmi range allowed minimum alerting times that were sufficient for acceptable pilot performance. The study findings will inform DAA system requirements for UAS with alternative surveillance equipment and aircraft performance capabilities. Implications on DAA display and sensor requirements are discussed.

unmanned aircraft systems↗
NASA NTRS2011

ALHAT System Validation

NASA has embarked on a multiyear technology development effort to develop a safe and precise lunar landing capability. The Autonomous Landing and Hazard Avoidance Technology (ALHAT) Project is investigating a range of landing hazard detection methods while developing a hazard avoidance capability to best field test the proper set of relevant autonomous GNC technologies. Ultimately, the advancement of these technologies through the ALHAT Project will provide an ALHAT System capable of enabling next generation lunar lander vehicles to globally land precisely and safely regardless of lighting condition. This paper provides an overview of the ALHAT System and describes recent validation experiments that have advanced the highly capable GNC architecture.

Brady, Tye↗
NASA NTRS2012

Near-Infrared (NIR) Raman Spectroscopy of Precambrian Carbonate Stromatolites with Post-Depositional Organic Inclusions

Raman spectroscopy has promising potential for future Mars missions as a non-contact detection technique for characterizing organic material and mineralogy. Such a capability will be useful for selecting samples for detailed analysis on a rover and for selecting samples for return to Earth. Stromatolites are important evidence for the earliest life on Earth and are promising targets for Mars investigations. Although constructed by microorganisms, stromatolites are organo-sedimentary structures that can be large enough to be discovered and investigated by a Mars rover. In this paper, we report the Raman spectroscopic investigations of the carbonate mineralogy and organic layering in a Precambrian (;1.5 Gyr old) stromatolite from the Crystal Spring Formation of Southern California. Ultraviolet (UV: 266 nm), visible (514 nm, 633 nm), and near-infrared (NIR: 785 nm, 1064 nm) Raman spectra are presented. We conclude that 1064 nm excitation is the optimal excitation wavelength for avoiding intrinsic fluorescence and detecting organic carbon within the carbonate matrix. Our results confirm that NIR Raman spectroscopy has important applications for future Mars missions.

Tanaka, Zuki↗
NASA NTRSDate not supplied

A Human-in-the-Loop Evaluation of ACAS Xu

As part of the Phase 2 UAS DAA MOPS, a Class 3 DAA system has been under development with the potential to resolve many of the limitations of Class 1 and 2 systems. A Class 3 system would combine the DAA and CA functions into a single, unified system, and would also extend the CA capabilities relative to TCAS II. Class 3 is enabled by the Airborne Collision Avoidance System (ACAS) XU, a next generation CA system developed specifically for UAS operations. Unlike Class 2 systems, ACAS XU provides CA protection against both cooperative and non-cooperative traffic. Class 3 systems also expand the CA logic to allow horizontal RAs in addition to vertical RAs. The purpose of the current study was to evaluate ACAS XU in a real-time, HITL simulation. The latest version of ACAS XU was implemented and pilots were tasked with responding to scripted traffic conflicts over the course of four experimental trials. Variables included the location of the ACAS XU guidance information (standalone vs. integrated) and traffic conflict type (DAA or CA threat). Sixteen active UAS pilots participated in the study, with ATC and ‘pseudo’ pilots acting as airspace confederates. Results showed that pilots were able to maintain DWC with ACAS XU at a rate comparable to previous research (~5%). Compliance rates to initial RAs were high (~90%) but dropped significantly when the target heading value issued during horizontal RAs were updated over the course of an encounter (30-70%). The implications of these findings on the display, alerting, and guidance requirements for Class 3 systems will be discussed.

unmanned aircraft systems↗
NASA NTRS2020

A Human-in-theLoop Evaluation of ACAS Xu

As part of the Phase 2 UAS DAA MOPS, a Class 3 DAA system has been under development with the potential to resolve many of the limitations of Class 1 and 2 systems. A Class 3 system would combine the DAA and CA functions into a single, unified system, and would also extend the CA capabilities relative to TCAS II. Class 3 is enabled by the Airborne Collision Avoidance System (ACAS) XU, a next generation CA system developed specifically for UAS operations. Unlike Class 2 systems, ACAS XU provides CA protection against both cooperative and non-cooperative traffic. Class 3 systems also expand the CA logic to allow horizontal RAs in addition to vertical RAs. The purpose of the current study was to evaluate ACAS XU in a real-time, HITL simulation. The latest version of ACAS XU was implemented and pilots were tasked with responding to scripted traffic conflicts over the course of four experimental trials. Variables included the location of the ACAS XU guidance information (standalone vs. integrated) and traffic conflict type (DAA or CA threat). Sixteen active UAS pilots participated in the study, with ATC and ‘pseudo’ pilots acting as airspace confederates. Results showed that pilots were able to maintain DWC with ACAS XU at a rate comparable to previous research (~5%). Compliance rates to initial RAs were high (~90%) but dropped significantly when the target heading value issued during horizontal RAs were updated over the course of an encounter (30-70%). The implications of these findings on the display, alerting, and guidance requirements for Class 3 systems will be discussed.

unmanned aircraft systems↗
NASA NTRSDate not supplied

A Human-in-the-Loop Evaluation of ACAS Xu

As part of the Phase 2 UAS DAA MOPS, a Class 3 DAA system has been under development with the potential to resolve many of the limitations of Class 1 and 2 systems. A Class 3 system would combine the DAA and CA functions into a single, unified system, and would also extend the CA capabilities relative to TCAS II. Class 3 is enabled by the Airborne Collision Avoidance System (ACAS) XU, a next generation CA system developed specifically for UAS operations. Unlike Class 2 systems, ACAS XU provides CA protection against both cooperative and non-cooperative traffic. Class 3 systems also expand the CA logic to allow horizontal RAs in addition to vertical RAs. The purpose of the current study was to evaluate ACAS XU in a real-time, HITL simulation. The latest version of ACAS XU was implemented and pilots were tasked with responding to scripted traffic conflicts over the course of four experimental trials. Variables included the location of the ACAS XU guidance information (standalone vs. integrated) and traffic conflict type (DAA or CA threat). Sixteen active UAS pilots participated in the study, with ATC and ‘pseudo’ pilots acting as airspace confederates. Results showed that pilots were able to maintain DWC with ACAS XU at a rate comparable to previous research (~5%). Compliance rates to initial RAs were high (~90%) but dropped significantly when the target heading value issued during horizontal RAs were updated over the course of an encounter (30-70%). The implications of these findings on the display, alerting, and guidance requirements for Class 3 systems will be discussed.

unmanned aircraft systems↗
DOE OSTI2025

Stability evaluation and mitigation strategies in advanced tokamaks using 3D MHD spectroscopy

Multi-modal, active 3D MHD spectroscopy is applied in high-performance advanced tokamak scenarios to study their stability time evolution, revealing an intriguing dependence on both and . A tailored applied 3D field provides a 3D plasma response to extract the growth rate of the least stable mode. The estimated growth rate finds a decrease in stability when the minimum in the safety factor (q) passes through 2.0 and reveals inherent risks of crossing an additional rational surface at integer q min , even above the usual q = 1 sawtooth condition. Based on this result, the potential scenario in which q min ~ 2 can be safely crossed during a more stable lower β N phase was investigated, and the improved stability of this scenario is confirmed by the estimated growth rate. This shows that 3D MHD spectroscopy can offer insights into strategies for improving stability by identifying the vulnerable aspects of such scenarios. In addition, the method highlights its potential for instability avoidance by enabling early detection of multiple modes, even before magnetic coils can measure them. The measured growth rate by the 3D MHD spectroscopy shows its reliability by exhibiting a correlation with the programmed rises in plasma beta across various high β N and high q min discharges. In addition, this method is successfully applied during rapidly evolving I p ramp-up phases, a key part of the scenario development. By achieving reasonable growth rate measurements at high-performance scenario developments, this technique contributes to the development of advanced diagnostic tools for tokamak scenario stability, which will help identify an effective pathway to stable, high-performance scenarios.

Yang, S. M. [Princeton Plasma Physics Laboratory (↗