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NASA NTRS1991

Gravitational Effects on Brain and Behavior

Visual, vestibular, tactile, proprioceptive, and perhaps auditory clues are combined with knowledge of commanded voluntary movement to produce a single, usually consistent, perception of spatial orientation. The recent Spacelab flights have provided especially valuable observations on the effects of weightlessness and space flight. The response of the otolith organs to weightlessness and readapting to Earth's gravitation is described. Reference frames for orientation are briefly discussed.

Young, Laurence R.↗

NASA NTRS1991

M.I.T./Canadian Vestibular Experiments on the Spacelab-1 Mission. Part 1: Sensory Adaptation to Weightlessness and Readaptation to One-G: An Overview

Experiments on human spatial orientation were conducted on four crewmembers of Space Shuttle Spacelab Mission 1. The conceptual background of the project, the relationship among the experiments, and their relevance to a 'sensory reinterpretation hypothesis' are presented. Detailed experiment procedures and results are presented in the accompanying papers in this series. The overall findings are discussed as they pertain to the following aspects of hypothesized sensory reinterpretation in weightlessness: (1) utricular otolith afferent signals are reinterpreted as indicating head translation rather than tilt, (2) sensitivity of reflex responses to footward acceleration is reduced, and (3) increased weighting is given to visual and tactile cues in orientation perception and posture control. Results suggest increased weighting of visual cues and reduced weighting of graviceptor signals in weightlessness.

Young, Laurence R.↗

NASA NTRS1991

Expert system training and control based on the fuzzy relation matrix

Fuzzy knowledge, that for which the terms of reference are not crisp but overlapped, seems to characterize human expertise. This can be shown from the fact that an experienced human operator can control some complex plants better than a computer can. Proposed here is fuzzy theory to build a fuzzy expert relation matrix (FERM) from given rules or/and examples, either in linguistic terms or in numerical values to mimic human processes of perception and decision making. The knowledge base is codified in terms of many implicit fuzzy rules. Fuzzy knowledge thus codified may also be compared with explicit rules specified by a human expert. It can also provide a basis for modeling the human operator and allow comparison of what a human operator says to what he does in practice. Two experiments were performed. In the first, control of liquid in a tank, demonstrates how the FERM knowledge base is elicited and trained. The other shows how to use a FERM, build up from linguistic rules, and to control an inverted pendulum without a dynamic model.

Ren, Jie↗

NASA NTRS1990

GPS composite clock software performance

Computer software for ensembling all the space vehicle (SV) and ground clocks of the Global Positioning Systems (GPS) was implemented at the Master Control Station (MCS) on 17 June 1990. Improved GPS time stability and steering control are predicted. The perceptions of both Air Force and outside users are assessed. Current performance is compared with theoretical predictions.

Satin, Arthur L.↗

NASA NTRS1991

A geochemical assessment of possible lunar ore formation

The Moon apparently formed without appreciable water or other relatively volatile materials. Interior concentrations of water or other volatile substances appear to be extremely low. On Earth, water is important to the genesis of nearly all types of ores. Thus, some have reasoned that only abundant elements would occur in ore concentrations. The definition and recognition of ores on the Moon challenge the imaginations and the terrestrial perceptions of ore bodies. Lunar ores included solar-wind soaked soils, which contain abundant but dilute H, C, N, and noble gases (including He-3). Oxygen must be mined; soils contain approximately 45 percent (wt). Mainstream processes of rock formation concentrated Si, Mg, Al, Fe, and Ca, and possibly Ti and Cr. The highland surface contains approximately 70 percent (wt) feldspar (mainly CaAl2Si2O8), which can be separated from some highland soils. Small fragments of dunite were collected; dunite may occur in walls and central peaks of some craters. Theoretical extensions of observations of lunar samples suggest that the Moon may have produced ores of trace elements. Some small fragments have trace-element concentrations 10(exp 4) times higher than the lunar average, indicating that effective geochemical separations occurred; processes included fractional crystallization, silicate immiscibility, vaporization and condensation, and sulfide metamorphism. Operations of these processes acting on indigenous materials and on meteoritic material in the regolith could have produced ores. Infalling carbonaceous meteorites and comets have added water and hydrocarbons that may have been cold-trapped. Vesicles in basalts, pyroclastic beads, and reported transient events suggest gag emission from the lunar interior; such gas might concentrate and transport rare elements. Large impacts may disperse ores or produce them through deposition of heat at depth and by vaporization and subsequent condensation. The main problem in assessing lunar resources is the ignorance about the largely unexplored Moon.

Haskin, Larry A.↗

NASA NTRS1990

Contour-map encoding of shape for early vision

Contour maps provide a general method for recognizing 2-D shapes. All but blank images give rise to such maps, and people are good at recognizing objects and shapes from them. The maps are encoded easily in long feature vectors that are suitable for recognition by an associative memory. These properties of contour maps suggest a role for them in early visual perception. The prevalence of direction sensitive neurons in the visual cortex of mammals supports this view.

Kanerva, Pentti↗

NASA NTRS1990

Sensor fusion II: Human and machine strategies; Proceedings of the Meeting, Philadelphia, PA, Nov. 6-9, 1989

Various papers on human and machine strategies in sensor fusion are presented. The general topics addressed include: active vision, measurement and analysis of visual motion, decision models for sensor fusion, implementation of sensor fusion algorithms, applying sensor fusion to image analysis, perceptual modules and their fusion, perceptual organization and object recognition, planning and the integration of high-level knowledge with perception, using prior knowledge and context in sensor fusion.

Schenker, Paul S.↗

NASA NTRS1990

Autonomous navigation and control of a Mars rover

A Mars rover will need to be able to navigate autonomously kilometers at a time. This paper outlines the sensing, perception, planning, and execution monitoring systems that are currently being designed for the rover. The sensing is based around stereo vision. The interpretation of the images use a registration of the depth map with a global height map provided by an orbiting spacecraft. Safe, low energy paths are then planned through the map, and expectations of what the rover's articulation sensors should sense are generated. These expectations are then used to ensure that the planned path is correctly being executed.

Miller, D. P.↗

NASA NTRS1991

Lasers revisited - Their superior utility for interstellar beacons, communications, and travel

This paper demonstrates reasons why research supporting SETI and Communication with Extraterrestrial Intelligence should be broadened to optical wavelengths rather than focusing almost entirely upon microwave wavelengths and technologies. New perceptions regarding the feasibility of laser technologies, along with reassessments of signal-to-noise considerations, show both the desirability and feasibility of optical interstellar transmissions, especially at IR and visible wavelengths. It is shown that utilization of the large bandwidths available at optical wavelengths greatly improves the possible use of such endeavors.

Rather, John D. G.↗

NASA NTRS1991

Parameter estimation in space systems using recurrent neural networks

The identification of time-varying parameters encountered in space systems is addressed, using artificial neural systems. A hybrid feedforward/feedback neural network, namely a recurrent multilayer perception, is used as the model structure in the nonlinear system identification. The feedforward portion of the network architecture provides its well-known interpolation property, while through recurrency and cross-talk, the local information feedback enables representation of temporal variations in the system nonlinearities. The standard back-propagation-learning algorithm is modified and it is used for both the off-line and on-line supervised training of the proposed hybrid network. The performance of recurrent multilayer perceptron networks in identifying parameters of nonlinear dynamic systems is investigated by estimating the mass properties of a representative large spacecraft. The changes in the spacecraft inertia are predicted using a trained neural network, during two configurations corresponding to the early and late stages of the spacecraft on-orbit assembly sequence. The proposed on-line mass properties estimation capability offers encouraging results, though, further research is warranted for training and testing the predictive capabilities of these networks beyond nominal spacecraft operations.

Parlos, Alexander G.↗

NASA NTRS1991

Simulation evaluation of the effects of time delay and motion on rotorcraft handling qualities

A study aimed at determining the effects of simulator characteristics on perceived handling qualities is discussed. Evaluations were conducted with a baseline set of rotorcraft dynamics, using a simple transfer-function model of an uncoupled helicopter, under different conditions of visual and overall time delays. As the visual and motion parameters were changed, differences in pilot opinion were found reflecting a change in the pilots' perceptions of handling qualities, rather than changes in the aircraft model itself. It is concluded that it is necessary to tailor the motion washout dynamics to suit the task, with reduced washouts for precision maneuvering as compared to aggressive maneuvering. Visual-delay data suggest that it may be better to allow some time delay in the visual path to minimize the mismatch between visual and motion, rather than eliminate the visual delay entirely through lead compensation.

Mitchell, David G.↗

NASA NTRS1990

Fault characterization of a multilayered perceptron network

The results of a set of simulation experiments conducted to quantify the effects of faults in a classification network implemented as a three-layered perception model are reported. The percentage of vectors misclassified by the classification network, the time taken for the network to stabilize, and the output values are measured. The results show that both transient and permanent faults have a significant impact on the performance of the network. Transient faults are also found to cause the network to be increasingly unstable as the duration of a transient is increased. The average percentage of the vectors misclassified is about 25 percent; after relearning, this is reduced to 10 percent. The impact of link faults is relatively insignificant in comparison with node faults (1 percent versus 19 percent misclassified after relearning). A study of the impact of hardware redundancy shows a linear increase in misclassifications with increasing hardware size.

Tan, Chang H.↗

NASA NTRS1991

Aeroacoustics of large wind turbines

This paper reviews published information on aerodynamically generated noise from large horizontal axis wind turbines operated for electric power generation. Methods are presented for predicting both the discrete frequency rotational noise components and the broadband noise components, and results are compared with measurements. Refraction effects that result in the formation of high-frequency shadow zones in the upwind direction and channeling effects for the low frequencies in the downwind direction are illustrated. Special topics such as distributed source effects in prediction and the role of building dynamics in perception are also included.

Hubbard, Harvey H.↗

NASA NTRS1990

NASA's Telerobotic Testbed

As part of the Advanced Technology Program in Telerobotics Technology conducted by NASA's Office of Aeronautics and Space Technology, a Telerobotics Testbed has been placed into use at the Jet Propulsion Laboratory. The Telerobotics Testbed represents an integration of the discipline technologies represented by its subsystems: (1) Operator Control Station, (2) Planning and Reasoning, (3) Run Time Control, (4) Sensing and Perception, and (5) Manipulation and Control Mechanization. The features provided initially by the Telerobotic Testbed are described both at the subsystem level and at the level of a fully integrated, end-to-end system. The capabilities of the total system as displayed experimentally are discussed, and the capabilities of which the Telerobotic Testbed will be capable are described. The experimental program to define the performance of the Telerobotic Testbed is discussed.

Stocky, J. F.↗

NASA NTRS1992

Training For Estimation Of Angles Via Perspective Displays

Training helps people estimate angles more accurately from perspective pictures of three-dimensional scenes on two-dimensional displays, according to report. Based on study in which subjects shown scene containing ground plane (represented by perspective display of irregularly spaced parallel lines) and reference cube and target cube floating above ground plane. Scene devised to represent scenes like those occurring in flight simulators and at robot-control stations, where selection of trajectories, perception of obstacles, and manipulation of objects required.

Tharp, Gregory K.↗

NASA NTRS1992

Effect Of Contrast On Perceived Motion Of A Plaid

Report desribes series of experiments examining effect of contrast on perception of moving plaids. Each plaid pattern used in experiments was sum of two drifting sinusoidal gratings of different orientations. One of many studies helping to show how brain processes visual information on moving patterns. When gratings forming plaid differ in contrast, apparent direction of motion of plaid biased up to 20 degrees toward direction of grating of higher contrast.

Stone, L. S.↗

NASA NTRS1991

Real-time earthquake monitoring: Early warning and rapid response

A panel was established to investigate the subject of real-time earthquake monitoring (RTEM) and suggest recommendations on the feasibility of using a real-time earthquake warning system to mitigate earthquake damage in regions of the United States. The findings of the investigation and the related recommendations are described in this report. A brief review of existing real-time seismic systems is presented with particular emphasis given to the current California seismic networks. Specific applications of a real-time monitoring system are discussed along with issues related to system deployment and technical feasibility. In addition, several non-technical considerations are addressed including cost-benefit analysis, public perceptions, safety, and liability.

Source record↗

NASA NTRS1991

Human response to aircraft noise

The human auditory system and the perception of sound are discussed. The major concentration is on the annnoyance response and methods for relating the physical characteristics of sound to those psychosociological attributes associated with human response. Results selected from the extensive laboratory and field research conducted on human response to aircraft noise over the past several decades are presented along with discussions of the methodology commonly used in conducting that research. Finally, some of the more common criteria, regulations, and recommended practices for the control or limitation of aircraft noise are examined in light of the research findings on human response.

Powell, Clemans A.↗