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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Evaluation of control and display configurations for helicopter shipboard operations

A simulation evaluation of several approach and landing flight-control configurations and of two out-of-the-cockpit display devices (a head-up display and a helmet-mounted display) was performed for the task of landing a helicopter on a destroyer in adverse weather. The results indicated that the ship airwake turbulence was the most significant environmental variable affecting hover performance. In addition, to achieve adequate landing performance, attitude-command control compensation was required for the pilot regardless of the display used. For improved performance with reduced pilot effort, a velocity-command, position-hold control system was desired.

Paulk, C. H., Jr.↗
NASA NTRS1984

Simulator investigations of side-stick controller/stability and control augmentation systems for night nap-of-earth flight

Several night nap-of-the-earth mission tasks were evaluated using a helmet-mounted display which provided a limited field-of-view image with superimposed flight control symbology. A wide range of stability and control augmentation designs was investigated. Variations in controller force-deflection characteristics and the number of axes controlled through an integrated side-stick controller were studied. In general, a small displacement controller is preferred over a stiffstick controller particularly for maneuvering flight. Higher levels of stability augmentation were required for IMC tasks to provide handling qualities comparable to those achieved for the same tasks conducted under simulated visual flight conditions. Previously announced in STAR as N82-23216

Landis, K. H.↗
NASA NTRS1985

Communications Headgear With Protective Features

Uncomplicated, inexpensive intercom protects head, face, and hearing. Adaptation of highly suitable stock helmet and face shield unit to stock intercom headset provided ideal unit, allowing wearer total use of hands and body while protecting head, face, and hearing. Unit allows wearer to work effectively, efficiently, and safely while communicating from remote areas that require special precautions. Total cost of fabricating unit, using stock parts and including labor, less than $100.

Ward, S. W.↗
NASA NTRS1984

Effects of External Loads on Human Head Movement Control Systems

The central and reflexive control strategies underlying movements were elucidated by studying the effects of external loads on human head movement control systems. Some experimental results are presented on dynamic changes weigh the addition of aviation helmet (SPH4) and lead weights (6 kg). Intended time-optimal movements, their dynamics and electromyographic activity of neck muscles in normal movements, and also in movements made with external weights applied to the head were measured. It was observed that, when the external loads were added, the subject went through complex adapting processes and the head movement trajectory and its derivatives reached steady conditions only after transient adapting period. The steady adapted state was reached after 15 to 20 seconds (i.e., 5 to 6 movements).

Nam, M. H.↗
NASA NTRS1984

Analysis of the magnetic field configuration of a filament-associated flare from X-ray, UV, and optical observations

X-ray and ultraviolet observations from SMM of a filament-associated event on November 22, 1980 are examined in conjunction with ground-based optical observations, in order to determine the magnetic field configuration involved in the flaring process. Evidence that the flare was produced by gradual energy release in a large sheared magnetic loop which interacted with another smaller loop is found. Nonthermal processes, as indicated by hard X-ray emission and impulsive UV kernels, were produced in the interaction of the two loops. Although this flare shared some of the characteristics of Long Duration (class II) Events, no indication of a helmet-type configuration, as generally envisaged for class II events, was found. On the contrary, the magnetic configuration of the November 22, 1980 event was more similar to that of a compact (class I) flare, although on a much larger spatial scale and longer time scale.

Cheng, C.-C.↗
NASA NTRS1983

Comments concerning magnetic fields as a possible cause of rapid, irregular variability of early-type stars

It is noted that it is helpful to divide the atmosphere of an early-type star into two parts: a photosphere and a mantle. The photosphere can be modeled satisfactorily by normal model-atmosphere procedures. When modeling the mantle, one must take account of the deposition of nonradiative heat and momentum and one should recognize that the mantles of hot stars do not appear to be uniform or spherically symmetric. Five areas of discrepancy between classical theory and observation are noted and a possible way of modeling the mantles of early-type stars is outlined. The model consists of arcades of magnetic loops which form helmet-type structures in the equatorial band of the star, and of coronal-hole-type structures emmanating from weak unipolar regions which are chiefly distributed at polar latitudes.

Underhill, A. B.↗
NASA NTRS1985

Evidence for systematic flows in the transition region around prominences

The solar transition region in the neighborhood of prominences has been studied from observations with the Ultraviolet Spectrometer and Polarimeter of NASA's Solar Maximum Mission satellite. Dopplergrams from observations of the transition-region lines C IV 1548 A and Si IV 1393 A, which are formed at about 100,000 K, give velocity amplitudes typically in the range + or - 15 km/s. Prominences are found to be located very close to dividing lines between areas of up- and down-drafts in the transition-region. The observed pattern suggests that the 100,000 K gas flows take place within arcades of magnetic loops, which most likely are part of the supporting magnetic structure for the prominence matter. An additional band of blue-ward Doppler shifts is frequently seen close to quiescent prominences. This may be the source of outward flowing matter along the helmet streamers above filament channels.

Engvold, O.↗
NASA NTRS1986

Adapted head- and eye-movement responses to added-head inertia

Adaptation to inertia added to the head was studied in men by mounting masses on a rigidly attached helmet until two- to ten-fold increases of inertia were produced, while an overhead suspension compensated for the weights. The observed changes in the eye and head movement coordination included increased head movement latencies, as well as changes in the eye movement amplitude, and later stabilizing alternate contractions of the neck muscles. Oscillopsia, or continual displacement or instability of the visual world, which is a symptom of a breakdown of space constancy, was prominent and consistent in the perceptual reports of the subjects. Although adaptation resulting from adding inertia to the head occurred much faster than that induced by adding prisms or lenses, it has similar perceptual and motor components that may be objectively studied in detail.

Gauthier, G. M.↗
NASA NTRS1986

Pilot vehicle interface on the advanced fighter technology integration F-16

This paper focuses on the work load aspects of the pilot vehicle interface in regard to the new technologies tested during AMAS Phase II. Subjects discussed in this paper include: a wide field-of-view head-up display; automated maneuvering attack system/sensor tracker system; master modes that configure flight controls and mission avionics; a modified helmet mounted sight; improved multifunction display capability; a voice interactive command system; ride qualities during automated weapon delivery; a color moving map; an advanced digital map display; and a g-induced loss-of-consciousness and spatial disorientation autorecovery system.

Dana, W. H.↗
NASA NTRS1988

Lightweight Video-Camera Head

Compact, lightweight video camera head constructed by remounting lens and charge-coupled-device image detector from small commercial video camera in separate assembly. Useful in robotics, artificial vision, and vision guidance systems. Designed to be mounted on visor of helmet to monitor motions of eyes in experiments on vestibulo-ocular reflexes.

Proctor, David R.↗
NASA NTRS1988

Analysis procedures and subjective flight results of a simulator validation and cue fidelity experiment

A joint experiment to investigate simulator validation and cue fidelity was conducted by the Dryden Flight Research Facility of NASA Ames Research Center (Ames-Dryden) and NASA Langley Research Center. The primary objective was to validate the use of a closed-loop pilot-vehicle mathematical model as an analytical tool for optimizing the tradeoff between simulator fidelity requirements and simulator cost. The validation process includes comparing model predictions with simulation and flight test results to evaluate various hypotheses for differences in motion and visual cues and information transfer. A group of five pilots flew air-to-air tracking maneuvers in the Langley differential maneuvering simulator and visual motion simulator and in an F-14 aircraft at Ames-Dryden. The simulators used motion and visual cueing devices including a g-seat, a helmet loader, wide field-of-view horizon, and a motion base platform.

Carr, Peter C.↗
NASA NTRS1987

The evolution of a coronal streamer prior to mass ejection

A model describing the quasi-static evolution of a coronal helmet streamer as it is inflated with excess mass was developed. The model produces a sequence of magnetostatic equilibria for a magnetic field configuration that includes a current sheet in the equatorial plane as well as distributed volume currents. The equilibrium solutions are given as Legendre series, and the height at which the current sheet starts is adjusted iteratively to maintain constant flux in the closed-field region. The model was fit to SMM coronagraph/polarimeter observations showing the slow growth of a coronal streamer prior to its disruption in association with an eruptive prominence and mass ejection on August 18, 1980. The results suggest that the early phase of this event is consistent with the quasi-static evolution of the corona in response to the slow addition of mass to the closed-field region of the streamer.

Wolfson, Richard↗
NASA NTRS1988

The effect of perspective displays on altitude and stability control in simulated rotary wing flight

The effect of perspective displays on flight performance is investigated using two simulation experiments. In the first, a perspective grid display was superimposed on computer-generated terrain and subjects attempted to maintain their initial attitude in a simulated hover using terrain and/or one of four grid patterns. Horizontal lines produced the best attitude control performance. In the second experiment, a square grid was studied in combination with various visual display configurations and grid attachment conditions. It was found that performance with the panel-mounted display was significantly worse than with the out-the-window or helmet-mounted displays. The results suggested that the partial grid attachment condition improved hovering performance with the panel-mounted display.

O'Donnell, K. A.↗
NASA NTRS1989

Helicopter flights with night-vision goggles: Human factors aspects

Night-vision goggles (NVGs) and, in particular, the advanced, helmet-mounted Aviators Night-Vision-Imaging System (ANVIS) allows helicopter pilots to perform low-level flight at night. It consists of light intensifier tubes which amplify low-intensity ambient illumination (star and moon light) and an optical system which together produce a bright image of the scene. However, these NVGs do not turn night into day, and, while they may often provide significant advantages over unaided night flight, they may also result in visual fatigue, high workload, and safety hazards. These problems reflect both system limitations and human-factors issues. A brief description of the technical characteristics of NVGs and of human night-vision capabilities is followed by a description and analysis of specific perceptual problems which occur with the use of NVGs in flight. Some of the issues addressed include: limitations imposed by a restricted field of view; problems related to binocular rivalry; the consequences of inappropriate focusing of the eye; the effects of ambient illumination levels and of various types of terrain on image quality; difficulties in distance and slope estimation; effects of dazzling; and visual fatigue and superimposed symbology. These issues are described and analyzed in terms of their possible consequences on helicopter pilot performance. The additional influence of individual differences among pilots is emphasized. Thermal imaging systems (forward looking infrared (FLIR)) are described briefly and compared to light intensifier systems (NVGs). Many of the phenomena which are described are not readily understood. More research is required to better understand the human-factors problems created by the use of NVGs and other night-vision aids, to enhance system design, and to improve training methods and simulation techniques.

Brickner, Michael S.↗
NASA NTRS1987

A space systems perspective of graphics simulation integration

Creation of an interactive display environment can expose issues in system design and operation not apparent from nongraphics development approaches. Large amounts of information can be presented in a short period of time. Processes can be simulated and observed before committing resources. In addition, changes in the economics of computing have enabled broader graphics usage beyond traditional engineering and design into integrated telerobotics and Artificial Intelligence (AI) applications. The highly integrated nature of space operations often tend to rely upon visually intensive man-machine communication to ensure success. Graphics simulation activities at the Mission Planning and Analysis Division (MPAD) of NASA's Johnson Space Center are focusing on the evaluation of a wide variety of graphical analysis within the context of present and future space operations. Several telerobotics and AI applications studies utilizing graphical simulation are described. The presentation includes portions of videotape illustrating technology developments involving: (1) coordinated manned maneuvering unit and remote manipulator system operations, (2) a helmet mounted display system, and (3) an automated rendezous application utilizing expert system and voice input/output technology.

Brown, R.↗
NASA NTRS1987

Telerobotics: A simulation facility for university research

An experimental telerobotics (TR) simulation suitable for studying human operator (H.O.) performance is described. Simple manipulator pick-and-place and tracking tasks allowed quantitative comparison of a number of calligraphic display viewing conditions. A number of control modes could be compared in this TR simulation, including displacement, rate and acceleratory control using position and force joysticks. A homeomorphic controller turned out to be no better than joysticks; the adaptive properties of the H.O. can apparently permit quite good control over a variety of controller configurations and control modes. Training by optimal control example seemed helpful in preliminary experiments. An introduced communication delay was found to produce decrease in performance. In considerable part, this difficulty could be compensated for by preview control information. That neurological control of normal human movement contains a data period of 0.2 second may relate to this robustness of H.O. control to delay. The Ames-Berkeley enhanced perspective display was utilized in conjunction with an experimental helmet mounted display system (HMD) that provided stereoscopic enhanced views.

Stark, L.↗
NASA NTRS1988

A piloted simulation investigation of yaw dynamics requirements for turreted gun use in low-level helicopter air combat

A piloted, fixed-base simulation study was conducted to investigate the handling qualities requirements for helicopter air-to-air combat using turreted guns in the near-terrain environment. The study used a version of the helicopter air combat system developed at NASA Ames Research Center for one-on-one air combat. The study focused on the potential trade-off between gun angular movement capability and required yaw axis response. Experimental variables included yaw axis response frequency and damping and the size of the gun-movement envelope. A helmet position and sighting system was used for pilot control of gun aim. Approximately 340 simulated air combat engagements were evaluated by pilots from the Army and industry. Results from the experiment indicate that a highly-damped, high frequency yaw response was desired for Level I handling qualities. Pilot preference for those characteristics became more pronounced as gun turret movement was restricted; however, a stable, slow-reacting platform could be used with a large turret envelope. Most pilots preferred to engage with the opponent near the own-ship centerline. Turret elevation restriction affected the engagement more than azimuth restrictions.

Decker, William A.↗
NASA NTRS1988

Telerobotics - Problems and research needs

With major emphasis on simulation, a university laboratory telerobotics facility permits problems to be approached by groups of graduate students. Helmet-mounded displays provide realism; the slaving of the display to the human operator's viewpoint gives a sense of 'telepresence' that may be useful for prolonged tasks. Using top-down three-dimensional model control of distant images allows distant images to be reduced to a few parameters to update the model used for display to the human operator in a preview mode to circumvent, in part, the communication delay. Also, the model can be used as a format for supervisory control and permit short-term local autonomous operations. Image processing algorithms can be made simpler and faster without trying to construct sensible images from the bottom. Control studies of telerobots lead to preferential manual control modes and basic paradigms for human motion and thence, perhaps, to redesign of robotic control, trajectory path planning, and rehabilitation prosthetics.

Stark, Lawrence↗