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At least 919 records · Page 51

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NASA NTRS1989

Optical pattern recognition; Proceedings of the Meeting, Los Angeles, CA, Jan. 17, 18, 1989

Papers on optical pattern recognition are presented, covering topics such as the estimation of satellite pose and motion parameters using a neural net tracker, associative memory, optical implmentation of programmable neural networks, optoelectronic neural networks, dynamic autoassociative neural memory, heteroassociative memory, bilinear pattern recognition processors, optical processing of optical correlation plane data, and a synthetic discriminant function-based nonlinear optical correlator. Other topics include an interactive optical-digital image processor, geometric transformations for video compression and human teleoperator display, quasiconformal remapping for compensation of human visual field defects, hybrid vision for automated spacecraft landing, advanced symbolic and inference optical correlation filters, and a rotationally invariant holographic tracking system. Additional topics include the detection of rotational and scale-varying objects with a programmable joint transform correlator, a single spatial light modulator binary nonlinear optical correlator, optical joint transform correlation, linear phase coefficient composite filters, and binary phase-only filters.

Liu, Hua-Kuang↗

NASA NTRS1991

Improved Rotary Transformer For Shaft-Position Indicator

Improved rotary transformer for Inductosyn (or equivalent) shaft-position-indicating circuit has pair of ferrite cores instead of the solid-iron cores. Designed with view toward decreasing excitation power (to maximum allowable 2 W) supplied to shaft-position-indicating circuit to increase its output signal and make tracking system less vulnerable to electromagnetic interference.

Mclyman, W. T.↗

NASA NTRS1990

Space simulation facilities providing a stable thermal vacuum facility

CBI has recently constructed the Intermediate Thermal Vacuum Facility. Built as a corporate facility, the installation will first be used on the Boost Surveillance and Tracking System (BSTS) program. It will also be used to develop and test other sensor systems. The horizontal chamber has a horseshoe shaped cross section and is supported on pneumatic isolators for vibration isolation. The chamber structure was designed to meet stability and stiffness requirements. The design process included measurement of the ambient ground vibrations, analysis of various foundation test article support configurations, design and analysis of the chamber shell and modal testing of the chamber shell. A detailed 3-D finite element analysis was made in the design stage to predict the lowest three natural frequencies and mode shapes and to identify local vibrating components. The design process is described and the results are compared of the finite element analysis to the results of the field modal testing and analysis for the 3 lowest natural frequencies and mode shapes. Concepts are also presented for stiffening large steel structures along with methods to improve test article stability in large space simulation facilities.

Tellalian, Martin L.↗

NASA NTRS1991

Fuzzy logic in autonomous orbital operations

Fuzzy logic can be used advantageously in autonomous orbital operations that require the capability of handling imprecise measurements from sensors. Several applications are underway to investigate fuzzy logic approaches and develop guidance and control algorithms for autonomous orbital operations. Translational as well as rotational control of a spacecraft have been demonstrated using space shuttle simulations. An approach to a camera tracking system has been developed to support proximity operations and traffic management around the Space Station Freedom. Pattern recognition and object identification algorithms currently under development will become part of this camera system at an appropriate level in the future. A concept to control environment and life support systems for large Lunar based crew quarters is also under development. Investigations in the area of reinforcement learning, utilizing neural networks, combined with a fuzzy logic controller, are planned as a joint project with the Ames Research Center.

Lea, Robert N.↗

NASA NTRS1991

Sliding mode control of magnetic suspensions for precision pointing and tracking applications

A recently developed nonlinear control method, sliding mode control, is examined as a means of advancing the achievable performance of space-based precision pointing and tracking systems that use nonlinear magnetic actuators. Analytic results indicate that sliding mode control improves performance compared to linear control approaches. In order to realize these performance improvements, precise knowledge of the plant is required. Additionally, the interaction of an estimating scheme and the sliding mode controller has not been fully examined in the literature. Estimation schemes were designed for use with this sliding mode controller that do not seriously degrade system performance. The authors designed and built a laboratory testbed to determine the feasibility of utilizing sliding mode control in these types of applications. Using this testbed, experimental verification of the authors' analyses is ongoing.

Misovec, Kathleen M.↗

NASA NTRS1991

Robotic control and inspection verification

Three areas of possible commercialization involving robots at the Kennedy Space Center (KSC) are discussed: a six degree-of-freedom target tracking system for remote umbilical operations; an intelligent torque sensing end effector for operating hand valves in hazardous locations; and an automatic radiator inspection device, a 13 by 65 foot robotic mechanism involving completely redundant motors, drives, and controls. Aspects concerning the first two innovations can be integrated to enable robots or teleoperators to perform tasks involving orientation and panal actuation operations that can be done with existing technology rather than waiting for telerobots to incorporate artificial intelligence (AI) to perform 'smart' autonomous operations. The third robot involves the application of complete control hardware redundancy to enable performance of work over and near expensive Space Shuttle hardware. The consumer marketplace may wish to explore commercialization of similiar component redundancy techniques for applications when a robot would not normally be used because of reliability concerns.

Davis, Virgil Leon↗

NASA NTRS1990

Enhancing orbital servicing operations: Providing positive and effective management of spare and installed hardware - A case study of the Hubble Space Telescope

The Satellite Resources Management and Tracking System was developed specifically for the Hubble Space Telescope (HST) program, and now, NASA has the ability to immediately access the necessary data for planning successful orbital satellite servicing operations. This system is an online, real-time data base system that contains a plethora of data on each item identified to support the HST throughout its planned 15 year life. Some of the information provided includes the current status, location, quantity, and history of each asset, a separate record for each discrete serial numbered item, procurement lead times on items sensitive to technology obsolescence, and the maintenance and repair history of each asset. Finally, details are provided on organizational, operational and logistics requirements.

Randolph, Joseph L.↗

NASA NTRS1990

The Goddard optical communications program

The main areas of research being conducted at NASA Goddard Space Flight Center are reviewed. Research on transmitter source technology is addressed, emphasizing the development of AlGaAs semiconductor laser diodes. Research on receiver technology is examined, and progress being made in the development of the Pointing, Acquisition, and Tracking System (PATS) is reviewed. Plans for an in-space technology demonstration are briefly discussed.

Seery, B. D.↗

NASA NTRS1991

A high data rate recorder for astronomy

A magnetic tape recorder developed for the special requirements of radio astronomy and geodesy is described. These requirements include a high bit packing density and long record times. The current version of this longitudinal recorder used by the Very Long Baseline Array (VLBA) records 5.5 Terabits on a 14-in diameter reel of inch-wide tape. A maximum record rate of 256 Mb/s is achieved in the VLBA configuration with one recorder operating at 4 ms and utilizing 32 of the heads in a single stack. The VLBA recorders have been tested using a longitudinal density of 2.25 fr/micron; 448 data + 56 system tracks are recorded in 14 passes, each lasting 50 min, for a total record time (at 128 Mb/s) of 12 h on 14-in diameter reel of inch-wide 13-microns-thick D1-equivalent tape.

Hinteregger, H. F.↗

NASA NTRS1992

Modified Synthetic-Discriminant-Function Optical Filter

Experiments demonstrated feasibility of synthetic-discriminant-function filter encoded in binary spatial light modulator. Filter is part of optoelectronic apparatus indicating degree of correlation between input image and any number of training images of same object at various positions and orientations. Used in optical correlator to recognize rotated images, or in tracking system to recognize moving vehicle or other substantially rigid object from any direction.

Reid, Max B.↗

NASA NTRS1991

Initial Hardware Development Schedule

The hardware development schedule for the Common Lunar Lander's (CLLs) tracking system is presented. Among the topics covered are the following: historical perspective, solution options, industry contacts, and the rationale for selection.

Culpepper, William X.↗

NASA NTRS1991

Summary report: A preliminary investigation into the use of fuzzy logic for the control of redundant manipulators

The Rice University Department of Mechanical Engineering and Materials Sciences' Robotics Group designed and built an eight degree of freedom redundant manipulator. Fuzzy logic was proposed as a control scheme for tasks not directly controlled by a human operator. In preliminary work, fuzzy logic control was implemented for a camera tracking system and a six degree of freedom manipulator. Both preliminary systems use real time vision data as input to fuzzy controllers. Related projects include integration of tactile sensing and fuzzy control of a redundant snake-like arm that is under construction.

Cheatham, John B., Jr.↗

NASA NTRS1992

Vaporizing particle velocimeter

A velocimeter measures flow characteristics of a flow traveling through a chamber in a given direction. Tracer particles are entrained in the flow and a source of radiant energy produces an output stream directed transversely to the chamber, having a sufficient intensity to vaporize the particles as they pass through the output stream. Each of the vaporized particles explodes to produce a shock wave and a hot core, and a flow visualization system tracks the motion of the hot cores and shock waves to measure the velocity of each tracer particle and the temperature of the flow around the tracer.

Weinstein, Leonard M.↗

NASA NTRS1991

TOPEX/Poseidon - The ocean topography experiment

The configuration of the TOPEX/Poseidon mission is discussed in an overview of the launch and experimental objectives related to the deployment planned for 1992. The spacecraft carries equipment for radar altimetry and precise orbit determination, and the instruments are expected to provide precise observations of global ocean dynamics. Six scientific instruments are described including the Laser Retroreflector Array, the Tracking System Receiver, and GPS Demonstration Receiver. Also described are the orbit configuration of the satellite, verification of system performance, and the techniques for data processing. The observations from the TOPEX/Poseidon experiment can provide data that is free of sea-level variabilities and describes the general circulation of the ocean and its variability.

Fu, Lee-Lueng↗

NASA NTRS1991

Optical correlators for automated rendezvous and capture

Two dimensional image correlation is a robust technique for recognizing known objects and determining their position with respect to the sensing platform. This capability is of paramount importance to vehicles which must rendezvous and capture using only on-board sensors and processors. Standard digital processors can provide the necessary correlations, but their speed, weight, size and power consumption make them undesirable components of an on-board tracking system. Optical correlators provide correlation results comparable to digital systems, but with a fraction of the size, weight and power and often many times faster. This presentation discusses the application of optical correlators to Automated Rendezvous & Capture (AR&C), and the specific work being done at the Johnson Space Center and DARPA in developing optical correlator technology.

Juday, Richard↗

NASA NTRS1993

Concept definition study for an extremely large aerophysics range facility

A conceptual design of a very large aeroballistic range is presented, as are its operational characteristics and procedures. The proposed model launcher is a two-stage light-gas gun, having a launch tube diameter of 254 mm, and the capability of accelerating a 14 kg launch mass to 6.1 km/sec. The gun's 91.4 cm diameter piston is driven by pressurized helium. High pressures in the central breech are contained by a multiple disk arrangement. The blast tank and sabot separation tank are described, as are methods for arresting sabot segments. The conceptual design of the range itself includes a 3.3 m diameter test or flight chamber some 330 m in length. Provisions are made for testing of free flight models and tests in which the model is confined by a track system. Methods for model deceleration and recovery are described. Provisions required for future addition of advanced model launchers such as an electromagnetic launcher or ram accelerator are addressed. Siting and safety issues are also addressed.

Swift, Hallock F.↗

NASA NTRS1993

TDRSS orbit determination using short baseline differenced carrier phase

This paper discusses a covariance study on the feasibility of using station-differenced carrier phase on short baselines to track the TDRSS satellites. Orbit accuracies for the TDRSS using station-differenced carrier phase data and range data collected from White Sands, NM are given for various configurations of ground stations and range data precision. A one-sigma-position position accuracy of 25 meters can be achieved using two orthogonal baselines of 100 km for the station-differenced phase data and range data with 1 m accuracy. Relevant configuration parameters for the tracking system and important sources of error are examined. The ability of these data to redetermine the position after a station keeping maneuver is addressed. The BRTS system, which is currently used for TDRSS orbit determination, is briefly described and its errors are given for comparison.

Nandi, S.↗

NASA NTRS1992

Ice tracking techniques, implementation, performance, and applications

Present techniques of ice tracking make use both of cross-correlation and of edge tracking, the former being more successful in heavy pack ice, the latter being critical for the broken ice of the pack margins. Algorithms must assume some constraints on the spatial variations of displacements to eliminate fliers, but must avoid introducing any errors into the spatial statistics of the measured displacement field. We draw our illustrations from the implementation of an automated tracking system for kinematic analyses of ERS-1 and JERS-1 SAR imagery at the University of Alaska - the Alaska SAR Facility's Geophysical Processor System. Analyses of the ice kinematic data that might have some general interest to analysts of cloud-derived wind fields are the spatial structure of the fields, and the evaluation and variability of average deformation and its invariants: divergence, vorticity and shear. Many problems in sea ice dynamics and mechanics can be addressed with the kinematic data from SAR.

Rothrock, D. A.↗