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At least 1,441 records · Page 80
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Man-machine cooperation in advanced teleoperation

Teleoperation experiments at JPL have shown that advanced features in a telerobotic system are a necessary condition for good results, but that they are not sufficient to assure consistently good performance by the operators. Two or three operators are normally used during training and experiments to maintain the desired performance. An alternative to this multi-operator control station is a man-machine interface embedding computer programs that can perform some of the operator's functions. In this paper we present our first experiments with these concepts, in which we focused on the areas of real-time task monitoring and interactive path planning. In the first case, when performing a known task, the operator has an automatic aid for setting control parameters and camera views. In the second case, an interactive path planner will rank different path alternatives so that the operator will make the correct control decision. The monitoring function has been implemented with a neural network doing the real-time task segmentation. The interactive path planner was implemented for redundant manipulators to specify arm configurations across the desired path and satisfy geometric, task, and performance constraints.

Fiorini, Paolo↗
NASA NTRS1992

Robust recognition of handwritten numerals based on dual cooperative network

An approach to robust recognition of handwritten numerals using two operating parallel networks is presented. The first network uses inputs in Cartesian coordinates, and the second network uses the same inputs transformed into polar coordinates. How the proposed approach realizes the robustness to local and global variations of input numerals by handling inputs both in Cartesian coordinates and in its transformed Polar coordinates is described. The required network structures and its learning scheme are discussed. Experimental results show that by tracking only a small number of distinctive features for each teaching numeral in each coordinate, the proposed system can provide robust recognition of handwritten numerals.

Lee, Sukhan↗
NASA NTRS1993

ALLY - An operator's associate for cooperative supervisory control systems

The design, implementation, and evaluation of ALLY, a computer-based associate for the human supervisor of a simulated satellite ground control system, is described. ALLY's dynamic intent inferencing abilities and system control properties are described. Experimental evaluation of ALLY compared performance of a two-person team with a person-ALLY team in the control of a simulated satellite ground control system.

Bushman, James B.↗
NASA NTRS1991

Control for two cooperating disparate manipulators

This research seeks to provide an advanced force control strategy for a flexible manipulator. Two main issues with force control of flexible arms are discussed: non-collocation and robustness.

Lew, Jae Young↗
NASA NTRS1993

Scientific goals of the Cooperative Multiscale Experiment (CME)

Mesoscale Convective Systems (MCS) form the focus of CME. Recent developments in global climate models, the urgent need to improve the representation of the physics of convection, radiation, the boundary layer, and orography, and the surge of interest in coupling hydrologic, chemistry, and atmospheric models of various scales, have emphasized the need for a broad interdisciplinary and multi-scale approach to understanding and predicting MCS's and their interactions with processes at other scales. The role of mesoscale systems in the large-scale atmospheric circulation, the representation of organized convection and other mesoscale flux sources in terms of bulk properties, and the mutually consistent treatment of water vapor, clouds, radiation, and precipitation, are all key scientific issues concerning which CME will seek to increase understanding. The manner in which convective, mesoscale, and larger scale processes interact to produce and organize MCS's, the moisture cycling properties of MCS's, and the use of coupled cloud/mesoscale models to better understand these processes, are also major objectives of CME. Particular emphasis will be placed on the multi-scale role of MCS's in the hydrological cycle and in the production and transport of chemical trace constituents. The scientific goals of the CME consist of the following: understand how the large and small scales of motion influence the location, structure, intensity, and life cycles of MCS's; understand processes and conditions that determine the relative roles of balanced (slow manifold) and unbalanced (fast manifold) circulations in the dynamics of MCS's throughout their life cycles; assess the predictability of MCS's and improve the quantitative forecasting of precipitation and severe weather events; quantify the upscale feedback of MCS's to the large-scale environment and determine interrelationships between MCS occurrence and variations in the large-scale flow and surface forcing; provide a data base for initialization and verification of coupled regional, mesoscale/hydrologic, mesoscale/chemistry, and prototype mesoscale/cloud-resolving models for prediction of severe weather, ceilings, and visibility; provide a data base for initialization and validation of cloud-resolving models, and for assisting in the fabrication, calibration, and testing of cloud and MCS parameterization schemes; and provide a data base for validation of four dimensional data assimilation schemes and algorithms for retrieving cloud and state parameters from remote sensing instrumentation.

Cotton, William↗
NASA NTRS1993

United States/Russia Space Cooperation Documentary

This video documents the initiative to develop a multinational, permanent space research laboratory. Historical background on the U.S. and Soviet manned space flight program as well as joint efforts such as the Apollo-Soyuz link up is shown. The current initiative will begin with collaborative missions involving NASA's space shuttle and Russia's Mir space station, and culminate in a permanently manned space station involving the U.S., Russia, Japan, Canada, and ESA. Shown are computer simulations of the proposed space station. Commentary is provided by the NASA administrator, former astronauts, cosmonauts, and Russian and American space experts.

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NASA NTRS1994

Space/ground systems as cooperating agents

Within NASA and the European Space Agency (ESA) it is agreed that autonomy is an important goal for the design of future spacecraft and that this requires on-board artificial intelligence. NASA emphasizes deep space and planetary rover missions, while ESA considers on-board autonomy as an enabling technology for missions that must cope with imperfect communications. ESA's attention is on the space/ground system. A major issue is the optimal distribution of intelligent functions within the space/ground system. This paper describes the multi-agent architecture for space/ground systems (MAASGS) which would enable this issue to be investigated. A MAASGS agent may model a complete spacecraft, a spacecraft subsystem or payload, a ground segment, a spacecraft control system, a human operator, or an environment. The MAASGS architecture has evolved through a series of prototypes. The paper recommends that the MAASGS architecture should be implemented in the operational Dutch Utilization Center.

Grant, T. J.↗
NASA NTRS1993

Cooperative GN&C development in a rapid prototyping environment

The Navigation, Control and Aeronautics Division (NCAD) at NASA-JSC is exploring ways of producing Guidance, Navigation and Control (GN&C) flight software faster, better, and cheaper. To achieve these goals NCAD established two hardware/software facilities that take an avionics design project from initial inception through high fidelity real-time hardware-in-the-loop testing. Commercially available software products are used to develop the GN&C algorithms in block diagram form and then automatically generate source code from these diagrams. A high fidelity real-time hardware-in-the-loop laboratory provides users with the capability to analyze mass memory usage within the targeted flight computer, verify hardware interfaces, conduct system level verification, performance, acceptance testing, as well as mission verification using reconfigurable and mission unique data. To evaluate these concepts and tools, NCAD embarked on a project to build a real-time 6 DOF simulation of the Soyuz Assured Crew Return Vehicle flight software. To date, a productivity increase of 185 percent has been seen over traditional NASA methods for developing flight software.

Bordano, Aldo↗
NASA NTRS1994

Breaking down barriers in cooperative fault management: Temporal and functional information displays

At the highest level, the fundamental question addressed by this research is how to aid human operators engaged in dynamic fault management. In dynamic fault management there is some underlying dynamic process (an engineered or physiological process referred to as the monitored process - MP) whose state changes over time and whose behavior must be monitored and controlled. In these types of applications (dynamic, real-time systems), a vast array of sensor data is available to provide information on the state of the MP. Faults disturb the MP and diagnosis must be performed in parallel with responses to maintain process integrity and to correct the underlying problem. These situations frequently involve time pressure, multiple interacting goals, high consequences of failure, and multiple interleaved tasks.

Potter, Scott S.↗
NASA NTRS1994

Cooperative control theory and integrated flight and propulsion control

This report documents the activities and research results obtained under a grant (NAG3-998) from the NASA Lewis Research Center. The focus of the research was the investigation of dynamic interactions between airframe and engines for advanced ASTOVL aircraft configurations, and the analysis of the implications of these interactions on the stability and performance of the airframe and engine control systems. In addition, the need for integrated flight and propulsion control for such aircraft was addressed. The major contribution of this research was the exposition of the fact that airframe and engine interactions could be present, and their effects could include loss of stability and performance of the control systems. Also, the significance of two directional, as opposed to one-directional, coupling was identified and explained. A multi variable stability and performance analysis methodology was developed, and applied to several candidate aircraft configurations. Also exposed was the fact that with interactions present along with some integrated control approaches, the engine command/limiting logic (which represents an important non-linear component of the engine control system) can impact closed-loop airframe/engine system stability. Finally, a brief investigation of control-law synthesis techniques appropriate for the class of systems was pursued, and it was determined that multi variable techniques, included model-following formulations of LQG and/or H (infinity) methods showed promise. However, for practical reasons, decentralized control architectures are preferred, which is an architecture incompatible with these synthesis methods.

Schmidt, David K.↗
NASA NTRS1995

Cooperative control theory and integrated flight and propulsion control

The major contribution of this research was the exposition of the fact that airframe and engine interactions could be present, and their effects could include loss of stability and performance of the control systems. Also, the significance of two directional, as opposed to one-directional, coupling was identified and explained. A multivariable stability and performance analysis methodology was developed, and applied to several candidate aircraft configurations. In these example evaluations, the significance of these interactions was underscored. Also exposed was the fact that with interactions present along with some integrated control approaches, the engine command/limiting logic (which represents an important nonlinear component of the engine control system) can impact closed-loop airframe/engine system stability. Finally, a brief investigation of control-law synthesis techniques appropriate for the class of systems was pursued, and it was determined that multivariable techniques, including model-following formulations of LQG and/or H infinity methods, showed promise. However, for practical reasons, decentralized control architectures are preferred, which is an architecture incompatible with these synthesis methods. The major contributions of the second phase of the grant was the development of conditions under which no decentralized controller could achieve closed loop system requirements on stability and/or performance. Sought were conditions that depended only on properties of the plant and the requirement, and independent of any particular control law or synthesis approach. Therefore, they could be applied a priori, before synthesis of a candidate control law. Under this grant, such conditions were found regarding stability, and encouraging initial results were obtained regarding performance.

Schmidt, David K.↗
NASA NTRS1995

Cooperative research in space sciences

This grant covered the period from July 1989 through September 30, 1995. The research covered a number of topics in the general area of space science. Specific research topics included: (1) Solar astronomy - largely in support of the Ulysses project; (2) Space Science - largely in support of instrumentation for several NASA satellite projects; (3) Cometary astronomy; and (4) Planetary Astronomy - largely supporting the NASA Infrared Heterodyne instrument.

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NASA NTRS1994

Cooperative research in space geodesy and crustal dynamics

This research grant, which covered the period of July 1991 to August 1994, was concerned with a variety of topics within the geodesy and crustal dynamics fields. The specific topics of this grant included satellite tracking and gravity field determinations and crustal dynamics (this concentrated of space geodetic site stability for VLBI sites). Summaries of the specific research projects are included along with a list of publications and presentations supported by this research grant.

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NASA NTRS1994

Cooperative research in terrestrial planetary geology and geophysics

This final report for the period of July 1991 to August 1994 covered a variety of topics concerning the study of Earth and Mars. The Earth studies stressed the interpretation of the MAGSAT crustal magnetic anomalies in order to determine the geological structure, mineralogical composition, magnetic nature, and the historical background of submarine features, and also featured work in the area of terrestrial remote sensing. Mars research included the early evolution of the Martian atmosphere and hydrosphere and the investigations of the large Martian impact basins. Detailed summaries of the research is included, along with lists of the publications resulting from this research.

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NASA NTRS1994

Cooperative research in high energy astrophysics

Details of the activities conducted under the joint effort of the University of Maryland and NASA Goddard Space Flight Center Laboratory for High Energy Astrophysics are detailed for the period July 1989 through April 1994. The research covered a variety of topics including: (1) detection of cosmic rays and studies of the solar modulation of galactic cosmic rays; (2) support work for several x-ray satellites; (3) high resolution gamma-ray spectroscopy of celestial sources; (4)theoretical astrophysics; and (5) active galaxies.

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