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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

The Real Time Interactive Display Environment (RTIDE), a display building tool developed by Space Shuttle flight controllers

NASA's Mission Control Center, located at Johnson Space Center, is incrementally moving from a centralized architecture to a distributed architecture. Starting with STS-29, some host-driven console screens will be replaced with graphics terminals driven by workstations. These workstations will be supplied realtime data first by the Real Time Data System (RTDS), a system developed inhouse, and then months later (in parallel with RTDS) by interim and subsequently operational versions of the Mission Control Center Upgrade (MCCU) software package. The Real Time Interactive Display Environment (RTIDE) was built by Space Shuttle flight controllers to support the rapid development of multiple new displays to support Shuttle flights. RTIDE is a display building tool that allows non-programmers to define object-oriented, event-driven, mouseable displays. Particular emphasis was placed on upward compatibility between RTIDE versions, ability to acquire data from different data sources, realtime performance, ability to modularly upgrade RTIDE, machine portability, and a clean, powerful user interface. The operational and organizational factors that drove RTIDE to its present form, the actual design itself, simulation and flight performance, and lessons learned in the process are discussed.

Kalvelage, Thomas A.↗
NASA NTRS1990

A real time neural net estimator of fatigue life

A neural net architecture is proposed to estimate, in real-time, the fatigue life of mechanical components, as part of the Intelligent Control System for Reusable Rocket Engines. Arbitrary component loading values were used as input to train a two hidden-layer feedforward neural net to estimate component fatigue damage. The ability of the net to learn, based on a local strain approach, the mapping between load sequence and fatigue damage has been demonstrated for a uniaxial specimen. Because of its demonstrated performance, the neural computation may be extended to complex cases where the loads are biaxial or triaxial, and the geometry of the component is complex (e.g., turbopump blades). The generality of the approach is such that load/damage mappings can be directly extracted from experimental data without requiring any knowledge of the stress/strain profile of the component. In addition, the parallel network architecture allows real-time life calculations even for high frequency vibrations. Owing to its distributed nature, the neural implementation will be robust and reliable, enabling its use in hostile environments such as rocket engines. This neural net estimator of fatigue life is seen as the enabling technology to achieve component life prognosis, and therefore would be an important part of life extending control for reusable rocket engines.

Troudet, T.↗
NASA NTRS1990

A real-time signal combining system for Ka-band feed arrays using maximum-likelihood weight estimates

A real-time digital signal combining system for use with Ka-band feed arrays is proposed. The combining system attempts to compensate for signal-to-noise ratio (SNR) loss resulting from antenna deformations induced by gravitational and atmospheric effects. The combining weights are obtained directly from the observed samples by using a sliding-window implementation of a vector maximum-likelihood parameter estimator. It is shown that with averaging times of about 0.1 second, combining loss for a seven-element array can be limited to about 0.1 dB in a realistic operational environment. This result suggests that the real-time combining system proposed here is capable of recovering virtually all of the signal power captured by the feed array, even in the presence of severe wind gusts and similar disturbances.

Vilnrotter, V. A.↗
NASA NTRS1989

Computer-Aided Software Engineering - An approach to real-time software development

A new software engineering discipline is Computer-Aided Software Engineering (CASE), a technology aimed at automating the software development process. This paper explores the development of CASE technology, particularly in the area of real-time/scientific/engineering software, and a history of CASE is given. The proposed software development environment for the Advanced Launch System (ALS CASE) is described as an example of an advanced software development system for real-time/scientific/engineering (RT/SE) software. The Automated Programming Subsystem of ALS CASE automatically generates executable code and corresponding documentation from a suitably formatted specification of the software requirements. Software requirements are interactively specified in the form of engineering block diagrams. Several demonstrations of the Automated Programming Subsystem are discussed.

Walker, Carrie K.↗
NASA NTRS1989

Hybrid interconnection structures for real-time parallel processing

The use of hybrid interconnection structures that combine link connections and bus connections for real-time parallel processing is discussed. Idealistic parallel computation models for two real-time computing applications are described with attention given to a tightly coupled network model for object tracking and a network model for image processing. Consideration is given to the following different interconnection structures: the crossbar, the hypercube, the circular linked array, and the bus array.

Kim, K. H.↗
NASA NTRS1989

Development of real-time software environments for NASA's modern telemetry systems

An effort has been made to maintain maximum performance and flexibility for NASA-Goddard's VLSI telemetry system elements through the development of two real-time systems: (1) the Base System Environment, which supports generic system integration and furnishes the basic porting of various manufacturers' cards, and (2) the Modular Environment for Data Systems, which supports application-specific developments and furnishes designers with a set of tested generic library functions that can be employed to speed up the development of such application-specific real-time codes. The performance goals and design rationale for these two systems are discussed.

Horner, Ward↗
NASA NTRS1990

Internal flow measurements of the SSME fuel preburner injector element using real time neutron radiography

Due to observations of unsteady flow in the Space Shuttle Main Engine fuel preburner injector element, several flow studies have been performed. Real time neutron radiography tests were recently completed. This technique provided real time images of MiL-c-7024 and Freon-22 flow through an aluminum liquid oxygen post model at three back pressures (0, 150, and 545 psig) and pressure drops up to 1000 psid. Separated flow appeared only while operating at back pressures of 0 and 150 psig. The behavior of separated flow was similar to that observed for water in a 3x acrylic model of the LOX post. On the average, separated flow appeared to reattach near the exit of the post when the ratio of pressure drop to supply pressure was about 0.75.

Lindsay, John T.↗
NASA NTRS1989

CHIMERA II - A real-time multiprocessing environment for sensor-based robot control

A multiprocessing environment for a wide variety of sensor-based robot system, providing the flexibility, performance, and UNIX-compatible interface needed for fast development of real-time code is addressed. The requirements imposed on the design of a programming environment for sensor-based robotic control is outlined. The details of the current hardware configuration are presented, along with the details of the CHIMERA II software. Emphasis is placed on the kernel, low-level interboard communication, user interface, extended file system, user-definable and dynamically selectable real-time schedulers, remote process synchronization, and generalized interprocess communication. A possible implementation of a hierarchical control model, the NASA/NBS standard reference model for telerobot control system is demonstrated.

Stewart, David B.↗
NASA NTRS1990

Performance degradation due to multiprogramming and system overheads in real workloads - Case study on a shared memory multiprocessor

The performance degradation due to the multiprogramming (MP) overhead in a parallel execution environment is quantified. In addition, total system overhead is also measured. A methodology, which estimates the MP overhead present in real workloads, is illustrated with real measurents. It is found that MP overhead usually consumes between 10 and 23 percent of the processing power available to parallel programs. The mean MP overhead is determined to be 16 percent which is well over half the total system overhead executed on the system (the mean system overhead is determined to be 24 percent of the processing power). It is found that MP overhead, total system overhead, and application completion time are all moderately correlated.

Dimpsey, R. T.↗
NASA NTRS1990

Real-time piloted simulation of fully automatic guidance and control for rotorcraft nap-of-the-earth (NOE) flight following planned profiles

Developing a single-pilot all-weather NOE capability requires fully automatic NOE navigation and flight control. Innovative guidance and control concepts are being investigated to (1) organize the onboard computer-based storage and real-time updating of NOE terrain profiles and obstacles; (2) define a class of automatic anticipative pursuit guidance algorithms to follow the vertical, lateral, and longitudinal guidance commands; (3) automate a decision-making process for unexpected obstacle avoidance; and (4) provide several rapid response maneuvers. Acquired knowledge from the sensed environment is correlated with the recorded environment which is then used to determine an appropriate evasive maneuver if a nonconformity is observed. This research effort has been evaluated in both fixed-base and moving-base real-time piloted simulations thereby evaluating pilot acceptance of the automated concepts, supervisory override, manual operation, and reengagement of the automatic system.

Clement, Warren F.↗
NASA NTRS1990

The near real time image navigation of pictures returned by Voyager 2 at Neptune

The development of a process for performing image navigation in near real time is described. The process was used to accurately determine the camera pointing for pictures returned by the Voyager 2 spacecraft at Neptune Encounter. Image navigation improves knowledge of the pointing of an imaging instrument at a particular epoch by correlating the spacecraft-relative locations of target bodies in inertial space with the locations of their images in a picture taken at that epoch. More than 8,500 pictures returned by Voyager 2 at Neptune were processed in near real time. The results were used in several applications, including improving pointing knowledge for nonimaging instruments ('C-smithing'), making 'Neptune, the Movie', and providing immediate access to geometrical quantities similar to those traditionally supplied in the Supplementary Experiment Data Record.

Underwood, Ian M.↗
NASA NTRS1991

Software Package For Real-Time Graphics

Software package for master graphics interactive console (MAGIC) at Western Aeronautical Test Range (WATR) of NASA Ames Research Center provides general-purpose graphical display system for real-time and post-real-time analysis of data. Written in C language and intended for use on workstation of interactive raster imaging system (IRIS) equipped with level-V Unix operating system. Enables flight researchers to create their own displays on basis of individual requirements. Applicable to monitoring of complicated processes in chemical industry.

Malone, Jacqueline C.↗
NASA NTRS1990

An AD100 implementation of a real-time STOVL aircraft propulsion system

A real-time dynamic model of the propulsion system for a Short Take-Off and Vertical Landing (STOVL) aircraft was developed for the AD100 simulation environment. The dynamic model was adapted from a FORTRAN based simulation using the dynamic programming capabilities of the AD100 ADSIM simulation language. The dynamic model includes an aerothermal representation of a turbofan jet engine, actuator and sensor models, and a multivariable control system. The AD100 model was tested for agreement with the FORTRAN model and real-time execution performance. The propulsion system model was also linked to an airframe dynamic model to provide an overall STOVL aircraft simulation for the purposes of integrated flight and propulsion control studies. An evaluation of the AD100 system for use as an aircraft simulation environment is included.

Ouzts, Peter J.↗
NASA NTRS1991

Fully automatic guidance and control for rotorcraft nap-of-the-Earth flight following planned profiles. Volume 1: Real-time piloted simulation

Developing a single-pilot, all-weather nap-of-the-earth (NOE) capability requires fully automatic NOE (ANOE) navigation and flight control. Innovative guidance and control concepts are investigated in a four-fold research effort that: (1) organizes the on-board computer-based storage and real-time updating of NOE terrain profiles and obstacles in course-oriented coordinates indexed to the mission flight plan; (2) defines a class of automatic anticipative pursuit guidance algorithms and necessary data preview requirements to follow the vertical, lateral, and longitudinal guidance commands dictated by the updated flight profiles; (3) automates a decision-making process for unexpected obstacle avoidance; and (4) provides several rapid response maneuvers. Acquired knowledge from the sensed environment is correlated with the forehand knowledge of the recorded environment (terrain, cultural features, threats, and targets), which is then used to determine an appropriate evasive maneuver if a nonconformity of the sensed and recorded environments is observed. This four-fold research effort was evaluated in both fixed-based and moving-based real-time piloted simulations, thereby, providing a practical demonstration for evaluating pilot acceptance of the automated concepts, supervisory override, manual operation, and re-engagement of the automatic system. Volume one describes the major components of the guidance and control laws as well as the results of the piloted simulations. Volume two describes the complete mathematical model of the fully automatic guidance system for rotorcraft NOE flight following planned flight profiles.

Clement, Warren F.↗
NASA NTRS1990

Real-time measurement of materials properties at high temperatures by laser produced plasmas

Determination of elemental composition and thermophysical properties of materials at high temperatures, as visualized in the context of containerless materials processing in a microgravity environment, presents a variety of unusual requirements owing to the thermal hazards and interferences from electromagnetic control fields. In addition, such information is intended for process control applications and thus the measurements must be real time in nature. A new technique is described which was developed for real time, in-situ determination of the elemental composition of molten metallic alloys such as specialty steel. The technique is based on time-resolved spectroscopy of a laser produced plasma (LPP) plume resulting from the interaction of a giant laser pulse with a material target. The sensitivity and precision were demonstrated to be comparable to, or better than, the conventional methods of analysis which are applicable only to post-mortem specimens sampled from a molten metal pool. The LPP technique can be applied widely to other materials composition analysis applications. The LPP technique is extremely information rich and therefore provides opportunities for extracting other physical properties in addition to the materials composition. The case in point is that it is possible to determine thermophysical properties of the target materials at high temperatures by monitoring generation and transport of acoustic pulses as well as a number of other fluid-dynamic processes triggered by the LPP event. By manipulation of the scaling properties of the laser-matter interaction, many different kinds of flow events, ranging from shock waves to surface waves to flow induced instabilities, can be generated in a controllable manner. Time-resolved detection of these events can lead to such thermophysical quantities as volume and shear viscosities, thermal conductivity, specific heat, mass density, and others.

Kim, Yong W.↗
NASA NTRS1990

Real-time fuzzy inference based robot path planning

This project addresses the problem of adaptive trajectory generation for a robot arm. Conventional trajectory generation involves computing a path in real time to minimize a performance measure such as expended energy. This method can be computationally intensive, and it may yield poor results if the trajectory is weakly constrained. Typically some implicit constraints are known, but cannot be encoded analytically. The alternative approach used here is to formulate domain-specific knowledge, including implicit and ill-defined constraints, in terms of fuzzy rules. These rules utilize linguistic terms to relate input variables to output variables. Since the fuzzy rulebase is determined off-line, only high-level, computationally light processing is required in real time. Potential applications for adaptive trajectory generation include missile guidance and various sophisticated robot control tasks, such as automotive assembly, high speed electrical parts insertion, stepper alignment, and motion control for high speed parcel transfer systems.

Pacini, Peter J.↗
NASA NTRS1991

Computerized inspection of real surfaces and minimization of their deviations

A method is developed for the minimization of gear tooth surface deviations between theoretical and real surfaces for the improvement of precision of surface manufacture. Coordinate measurement machinery is used to determine a grid of surface coordinates. Theoretical calculations are made for the grid points. A least-square method is used to minimize the deviations between real and theoretical surfaces by altering the manufacturing machine-tool settings. An example is given for a hypoid gear.

Litvin, Faydor L.↗
NASA NTRS1991

A case study for the real-time experimental evaluation of the VIPER microprocessor

An experiment to evaluate the applicability of the Verifiable Integrated Processor for Enhanced Reliability (VIPER) microprocessor to real time control is described. The VIPER microprocessor was invented by the Royal Signals and Radar Establishment (RSRE), U.K., and is an example of the use of formal mathematical methods for developing electronic digital systems with a high degree of assurance on the system design and implementation correctness. The experiment consisted of selecting a control law, writing the control law algorithm for the VIPER processor, and providing real time, dynamic inputs into the processor and monitoring the outputs. The control law selected and coded for the VIPER processor was the yaw damper function of an automatic landing program for a 737 aircraft. The mechanisms for interfacing the VIPER Single Board Computer to the VAX host are described. Results include run time experiences, performance evaluation, and comparison of VIPER and FORTRAN yaw damper algorithm output for accuracy estimation.

Carreno, Victor A.↗