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At least 1,171 records · Page 65

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NASA NTRS1989

Experiences in teleoperation of land vehicles

Teleoperation of land vehicles allows the removal of the operator from the vehicle to a remote location. This can greatly increase operator safety and comfort in applications such as security patrol or military combat. The cost includes system complexity and reduced system performance. All feedback on vehicle performance and on environmental conditions must pass through sensors, a communications channel, and displays. In particular, this requires vision to be transmitted by close-circuit television with a consequent degradation of information content. Vehicular teleoperation, as a result, places severe demands on the operator. Teleoperated land vehicles have been built and tested by many organizations, including Sandia National Laboratories (SNL). The SNL fleet presently includes eight vehicles of varying capability. These vehicles have been operated using different types of controls, displays, and visual systems. Experimentation studying the effects of vision system characteristics on off-road, remote driving was performed for conditions of fixed camera versus steering-coupled camera and of color versus black and white video display. Additionally, much experience was gained through system demonstrations and hardware development trials. The preliminary experimental findings and the results of the accumulated operational experience are discussed.

Mcgovern, Douglas E.↗

NASA NTRS1989

Development of a stereo 3-D pictorial primary flight display

Computer-generated displays are becoming increasingly popular in aerospace applications. The use of stereo 3-D technology provides an opportunity to present depth perceptions which otherwise might be lacking. In addition, the third dimension could also be used as an additional dimension along which information can be encoded. Historically, the stereo 3-D displays have been used in entertainment, in experimental facilities, and in the handling of hazardous waste. In the last example, the source of the stereo images generally has been remotely controlled television camera pairs. The development of a stereo 3-D pictorial primary flight display used in a flight simulation environment is described. The applicability of stereo 3-D displays for aerospace crew stations to meet the anticipated needs for 2000 to 2020 time frame is investigated. Although, the actual equipment that could be used in an aerospace vehicle is not currently available, the lab research is necessary to determine where stereo 3-D enhances the display of information and how the displays should be formatted.

Nataupsky, Mark↗

NASA NTRS1988

Geometric database maintenance using CCTV cameras and overlay graphics

An interactive graphics system using closed circuit television (CCTV) cameras for remote verification and maintenance of a geometric world model database has been demonstrated in GE's telerobotics testbed. The database provides geometric models and locations of objects viewed by CCTV cameras and manipulated by telerobots. To update the database, an operator uses the interactive graphics system to superimpose a wireframe line drawing of an object with known dimensions on a live video scene containing that object. The methodology used is multipoint positioning to easily superimpose a wireframe graphic on the CCTV image of an object in the work scene. An enhanced version of GE's interactive graphics system will provide the object designation function for the operator control station of the Jet Propulsion Laboratory's telerobot demonstration system.

Oxenberg, Sheldon C.↗

NASA NTRS1990

Mariner 9 observations of the south polar cap of Mars - Evidence for residual CO2 frost

The first spacecraft observations of the south residual polar cap of Mars were obtained by the Mariner 9 orbiter during the Martian southern summer season, 1971-1972. Analyses of Viking orbiter observations obtained 3 Mars years later have shown that residual carbon dioxide frost was present at the south polar cap in 1977. In this study, Mariner 9 infrared interferometer spectrometer spectra and television camera images are used in conjuction with multispectral thermal emission models to constrain the temperatures of dark bare ground and bright frost regions within the south residual cap. The results provide strong evidence that carbon dioxide frost was present throughout the summer season despite the fact that the residual frost deposits observed by Mariner 9 were less extensive than those observed by Viking.

Paige, D. A.↗

NASA NTRS1989

Precise measurement of asteroid sizes and shapes from occultations

The observational techniques (including photoelectric observations, television recordings, and visual timings) used to measure asteroid dimensions from occultations of stars by asteroids are discussed together with the methods of analysis appropriate to occultation data. Results are presented on the determinations of asteroid diameter, density, and internal structure measures learned from occultations of 36 asteroids. Prospects for continued effective applications of the occultation technique to asteroid studies are discussed.

Millis, R. L.↗

NASA NTRS1989

Application of visual psychophysics to the design of video systems for use in space

A series of two-alternative forced choice experiments was conducted to compare the sharpness of televised moving images sampled using cardinal or diagonal patterns with reference images of varying resolution. The results indicate that both image sampling and resolution orientation play an important role in determining apparent sharpness of the images. If an image has better cardinal than diagonal resolution, the apparent sharpness is significantly greater. Thus, if the polar distribution of resolution is limited by the sampling process, diagonal sampling can be expected to yield a sharper image than cardinal sampling with the same number of pixels.

Glenn, William E.↗

NASA NTRS1991

Stereoscopic Configurations To Minimize Distortions

Proposed television system provides two stereoscopic displays. Two-camera, two-monitor system used in various camera configurations and with stereoscopic images on monitors magnified to various degrees. Designed to satisfy observer's need to perceive spatial relationships accurately throughout workspace or to perceive them at high resolution in small region of workspace. Potential applications include industrial, medical, and entertainment imaging and monitoring and control of telemanipulators, telerobots, and remotely piloted vehicles.

Diner, Daniel B.↗

NASA NTRS1990

State of the art in video system performance

The closed circuit television (CCTV) system that is onboard the Space Shuttle has the following capabilities: camera, video signal switching and routing unit (VSU); and Space Shuttle video tape recorder. However, this system is inadequate for use with many experiments that require video imaging. In order to assess the state-of-the-art in video technology and data storage systems, a survey was conducted of the High Resolution, High Frame Rate Video Technology (HHVT) products. The performance of the state-of-the-art solid state cameras and image sensors, video recording systems, data transmission devices, and data storage systems versus users' requirements are shown graphically.

Lewis, Michael J.↗

NASA NTRS1990

Rocket observations of the ultraviolet spectrum of comet Austin (1989c1)

Long slit ultraviolet spectra of Comet Austin (1989c1) were obtained from a sounding rocket experiment launched from White Sands Missile Range, New Mexico, on 21 April 1990 at 1015 UT. The instrument, known as the Faint Object Telescope, consisted of f/15.5 Dall-Kirkham telescope, a Rowland Circle spectrograph and a microchannel plate intensifier coupled to a Reticon diode array. An onboard television camera transmitted images to the ground during flight, which permitted real-time maneuvers in order to center the comet in the entrance slit. The comet was held near the center of the slit for approximately 270 seconds by sending six pointing corrections, all but one of which was less than 30 arcseconds. The comet's parameters at the time of observation, along with the characteristics of the instrument, are given.

Sahnow, D. J.↗

NASA NTRS1991

Potential commercial uses of EOS remote sensing products

The instrument complement of the Earth Observing System (EOS) satellite system will generate data sets with potential interest to a variety of users who are now just beginning to develop geographic information systems tailored to their special applications and/or jurisdictions. Other users may be looking for a unique product that enhances competitive position. The generally distributed products from EOS will require additional value added processing to derive the unique products desired by specific users. Entrepreneurs have an opportunity to create these proprietary level 4 products from the EOS data sets. Specific instruments or collections of instruments could provide information for crop futures trading, mineral exploration, television and printed medium news products, regional and local government land management and planning, digital map directories, products for third world users, ocean fishing fleet probability of harvest forecasts, and other areas not even imagined at this time. The projected level 3 product are examined that will be available at launch from EOS instruments and commercial uses of the data after value added processing is estimated.

Thompson, Leslie L.↗

NASA NTRS1991

NASA/Ames Research Center DC-8 data system

In-flight facility data acquisition, distribution, and recording on the NASA Ames Research Center (ARC) DC-8 are performed by the Data Acquisition and Distribution System (DADS). Navigational and environmental data collected by the DADS are converted to engineering units and distributed real-time to investigator stations once per second. Selected engineering units data are printed and displayed on closed circuit television monitors throughout flights. An in-flight graphical display of the DC-8 flight track (with barbs indicating wind direction and magnitude) has recently been added to the DADS capabilities. Logging of data run starts/stops and commentary from the mission director are also provided. All data are recorded to hard disk in-flight and archived to tape medium post-flight. Post-flight, hard copies of the track map and mission director's log are created by the DADS. The DADS is a distributed system consisting of a data subsystem, an Avionic Serial Data-to-VMEbus (ASD2VME) subsystem, and a host subsystem. Each subsystem has a dedicated central processing unit (CPU) and is capable of stand-alone operation. All three subsystems are housed in a single 20-slot VME chassis and communicate with each other over the VMEbus. The data and host subsystems are briefly discussed, and the DC-8 DADS internal configuration and system block diagram are presented.

Cherniss, S. C.↗

NASA NTRS1990

Time and frequency comparisons in Europe by means of ECS 5 geostationary satellite

A time synchronization experiment between some European laboratories using the passive television method applied to the signals broadcasted by Eutelsat I-F5 telecommunication satellite was completed in 1990. The results obtained in the last period, when also range measurements from a Telespazio ground station were performed, are analyzed to evaluate the accuracy level of the time comparisons corrected for the effect of the satellite movement with position data obtained either from the European Space Agency (ESA) or from orbit determination with range data entered into GEODYN program of NASA/GSFC.

Cordara, Franco↗

NASA NTRS1991

Optical joint correlator for real-time image tracking and retinal surgery

A method for tracking an object in a sequence of images is described. Such sequence of images may, for example, be a sequence of television frames. The object in the current frame is correlated with the object in the previous frame to obtain the relative location of the object in the two frames. An optical joint transform correlator apparatus is provided to carry out the process. Such joint transform correlator apparatus forms the basis for laser eye surgical apparatus where an image of the fundus of an eyeball is stabilized and forms the basis for the correlator apparatus to track the position of the eyeball caused by involuntary movement. With knowledge of the eyeball position, a surgical laser can be precisely pointed toward a position on the retina.

Juday, Richard D.↗

NASA NTRS1990

Lunar rover developments at JPL

Results of previous JPL developments are summarized and the current work related to lunar roving missions is discussed. Objectives of a long lunar transverse are reviewed and include lunar resource prospecting and base site surveys. Rover design criteria are presented, noting that payload instrumentation would include both television cameras for driving and cameras producing panoramic facsimile for high-fidelity scientific imaging and landmark navigation, as well as a multipurpose imaging system with multispectral, close-up, and microscopic capabilities. Instrumentation providing for chemical and mineral analysis, a gravimeter, and a magnetometer are also important. Rover performance requirements include a capability to support a 50 kg payload mass with a rover mass of 500 to 600 kg, powering and supporting the payload, managing the on-board resources available to each instrument, and handling all of the mission data. Desert tests of lunar roving navigation and field geology are discussed.

Burke, James D.↗

NASA NTRS1990

Performance of a modified feedback loop adaptive array with TVRO satellite signals

Performance of an experimental adaptive antenna array system is evaluated using television receive-only (TVRO) satellite signals. The experimental system is a sidelobe canceller with two auxiliary channels. Modified feedback loops are used to enhance the suppression of weak interfering signals. The modified feedback loops used two spatialy separated antennas, each with an individual amplifier for each auxiliary channel. Thus, the experimental system uses five antenna elements. Instead of using five separate antennas, a reflector antenna with multiple feeds is used to receive signals from various TVRO satellites. The details of the earth station are given. It is shown that the experimental system can null up to two signals originating from interfering TVRO satellites while receiving the signals from a desired TVRO satellite.

Steadman, Karl N.↗

NASA NTRS1990

Signal-to-noise ratios in IUE SWP-LO spectra of chromospheric emission-line sources

The short-wavelength-prime (SWP) detector of the International Ultraviolet Explorer should operate near the photon-counting limit, but the noise levels in flat-field images are several times higher. The exaggerated noise can be traced to the incomplete removal of the pixel-to-pixel granularity of the television frames by the prevailing spectral image processing system. An empirical noise model for the current-epoch photometric linearization strategy and one for a hypothetical processing system that achieves complete flat fielding of the raw images are derived. A formula is then proposed to predict the signal-to-noise ratio in the measured flux of an emission line (possibly superimposed on a smooth continuum) in an IUE low-dispersion (5 A resolution) far-ultraviolet (1150 A-1950 A) spectrum as recorded with the SWP camera. For illustration, the formula is specialized to the important C IV 1549 A feature of F-K stars. The S/N relation permits one to determine sensitivity limits, upper limits in faint exposures, and optimum exposure times.

Ayres, Thomas R.↗

NASA NTRS1991

Lightning flash mensuration using video from the Space Shuttle Columbia (STS-32)

Using the payload bay television cameras from various Space Shuttle missions, a study was performed to investigate the relationship between the size and duration of lightning flashes, though separated by 1-100 km, that appeared to be flashing in synchronization. The area, duration, and rate of propagation of the lightning in these storms was also studied. By employing the analytical methods described, the use of deinterlaced video of lightning observed from STS-32 provides the highest sampling rate ever utilized for this purpose from space (1 image each 16.7 m/sec).

Pitts, David E.↗

NASA NTRS1990

Proposed advanced satellite applications utilizing space nuclear power systems

A review of the status of space nuclear reactor systems and their possible applications is presented. Such systems have been developed over the past twenty years and are capable of use in various military and civilian applications in the 5-1000-kWe power range. The capabilities and limitations of the currently proposed nuclear reactor systems are summarized. Statements of need are presented from DoD, DOE, and NASA. Safety issues are identified, and if they are properly addressed they should not pose a hindrance. Applications are summarized for the DoD, DOE, NASA, and the civilian community. These applications include both low- and high-altitude satellite surveillance missions, communications satellites, planetary probes, low- and high-power lunar and planetary base power systems, broadband global telecommunications, air traffic control, and high-definition television.

Bailey, Patrick G.↗