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At least 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Production of Reliable Flight Crucial Software: Validation Methods Research for Fault Tolerant Avionics and Control Systems Sub-Working Group Meeting

The state of the art in the production of crucial software for flight control applications was addressed. The association between reliability metrics and software is considered. Thirteen software development projects are discussed. A short term need for research in the areas of tool development and software fault tolerance was indicated. For the long term, research in format verification or proof methods was recommended. Formal specification and software reliability modeling, were recommended as topics for both short and long term research.

Dunham, J. R.↗
NASA NTRS1982

The analysis of the statistical and historical information gathered during the development of the Shuttle Orbiter Primary Flight Software

The results of an effort to thoroughly and objectively analyze the statistical and historical information gathered during the development of the Shuttle Orbiter Primary Flight Software are given. The particular areas of interest include cost of the software, reliability of the software, requirements for the software and how the requirements changed during development of the system. Data related to the current version of the software system produced some interesting results. Suggestions are made for the saving of additional data which will allow additional investigation.

Simmons, D. B.↗
NASA NTRS1981

A high order approach to flight software development and testing

The use of a software development facility is discussed as a means of producing a reliable and maintainable ECS software system, and as a means of providing efficient use of the ECS hardware test facility. Principles applied to software design are given, including modularity, abstraction, hiding, and uniformity. The general objectives of each phase of the software life cycle are also given, including testing, maintenance, code development, and requirement specifications. Software development facility tools are summarized, and tool deficiencies recognized in the code development and testing phases are considered. Due to limited lab resources, the functional simulation capabilities may be indispensable in the testing phase.

Steinbacher, J.↗
NASA NTRS1982

Development of the Galileo Attitude and Articulation Control Subsystem flight software

The ongoing design and implementation of the Project Galileo Attitude and Articulation Control Subsystem (AACS) flight software is outlined, as well as the more important problems that were experienced in the development of this software. The important characteristics of the Galileo spacecraft are described, as are the major requirements driving the software design. The important features of the design are stated and discussed, and a modes and tasks transition diagram is presented. The AACS software implementation is covered, and the algorithms active in each task are shown. Finally, some of the design and management techniques used in the course of the software development are discussed.

Krasner, S. M.↗
NASA NTRS1981

LANDSAT-D flight segment operations manual. Appendix B: OBC software operations

The LANDSAT 4 satellite contains two NASA standard spacecraft computers and 65,536 words of memory. Onboard computer software is divided into flight executive and applications processors. Both applications processors and the flight executive use one or more of 67 system tables to obtain variables, constants, and software flags. Output from the software for monitoring operation is via 49 OBC telemetry reports subcommutated in the spacecraft telemetry. Information is provided about the flight software as it is used to control the various spacecraft operations and interpret operational OBC telemetry. Processor function descriptions, processor operation, software constraints, processor system tables, processor telemetry, and processor flow charts are presented.

Talipsky, R.↗
NASA NTRS1983

Preliminary description of the area navigation software for a microcomputer-based Loran-C receiver

The development of new software implementation of this software on a microcomputer (MOS 6502) to provide high quality navigation information is described. This software development provides Area/Route Navigation (RNAV) information from Time Differences (TDs) in raw form using an elliptical Earth model and a spherical model. The software is prepared for the microcomputer based Loran-C receiver. To compute navigation infomation, a (MOS 6502) microcomputer and a mathematical chip (AM 9511A) were combined with the Loran-C receiver. Final data reveals that this software does indeed provide accurate information with reasonable execution times.

Oguri, F.↗
NASA NTRS1984

An approach to software cost estimation

A general procedure for software cost estimation in any environment is outlined. The basic concepts of work and effort estimation are explained, some popular resource estimation models are reviewed, and the accuracy of source estimates is discussed. A software cost prediction procedure based on the experiences of the Software Engineering Laboratory in the flight dynamics area and incorporating management expertise, cost models, and historical data is described. The sources of information and relevant parameters available during each phase of the software life cycle are identified. The methodology suggested incorporates these elements into a customized management tool for software cost prediction. Detailed guidelines for estimation in the flight dynamics environment developed using this methodology are presented.

Mcgarry, F.↗
NASA NTRS1983

Current research in the Software Engineering Laboratory (SEL)

The basic goal of software engineering is to produce the best possible software at the lowest possible cost. Many practices, tools, and techniques (collectively referred to as technologies) were developed that purport to help do this, some of which have become widely accepted in the software industry. However, few of these technologies were effectively evaluated experimentally. This is due in large part to an insufficient understanding of the software development process, a lack of recognized standards for measurement, and the prohibitive cost of large-scale controlled experiments. The analysis described addresses some of these issues. The specific objectives of this study were to: measure technology use in a production environment; develop a model for evaluating software engineering technologies; and evaluate the effects of productivity and reliability of some specific technologies.

Card, D.↗
NASA NTRS1984

SAGA: A project to automate the management of software production systems

The project to automate the management of software production systems is described. The SAGA system is a software environment that is designed to support most of the software development activities that occur in a software lifecycle. The system can be configured to support specific software development applications using given programming languages, tools, and methodologies. Meta-tools are provided to ease configuration. Several major components of the SAGA system are completed to prototype form. The construction methods are described.

Campbell, R. H.↗
NASA NTRS1985

Space Station Software Issues

Issues in the development of software for the Space Station are discussed. Software acquisition and management, software development environment, standards, information system support for software developers, and a future software advisory board are addressed.

Voigt, S.↗
NASA NTRS1984

Writing executable assertions to test flight software

An executable assertion is a logical statement about the variables or a block of code. If there is no error during execution, the assertion statement results in a true value. Executable assertions can be used for dynamic testing of software. They can be employed for validation during the design phase, and exception and error detection during the operation phase. The present investigation is concerned with the problem of writing executable assertions, taking into account the use of assertions for testing flight software. They can be employed for validation during the design phase, and for exception handling and error detection during the operation phase The digital flight control system and the flight control software are discussed. The considered system provides autopilot and flight director modes of operation for automatic and manual control of the aircraft during all phases of flight. Attention is given to techniques for writing and using assertions to test flight software, an experimental setup to test flight software, and language features to support efficient use of assertions.

Mahmood, A.↗
NASA NTRS1984

Proceedings of the Ninth Annual Software Engineering Workshop

Experiences in measurement, utilization, and evaluation of software methodologies, models, and tools are discussed. NASA's involvement in ever larger and more complex systems, like the space station project, provides a motive for the support of software engineering research and the exchange of ideas in such forums. The topics of current SEL research are software error studies, experiments with software development, and software tools.

Source record↗
NASA NTRS1985

Annotated bibliography of Software Engineering Laboratory literature

An annotated bibliography of technical papers, documents, and memorandums produced by or related to the Software Engineering Laboratory is presented. More than 100 publications are summarized. These publications are summarized. These publications cover many areas of software engineering and range from research reports to software documentation. This document has been updated and reorganized substantially since the original version (SEL-82-006, November 1982). All materials are grouped into five general subject areas for easy reference: (1) the software engineering laboratory; (2) software tools; (3) models and measures; (4) technology evaluations; and (5) data collection. An index further classifies these documents by specific topic.

Source record↗
NASA NTRS1985

Space station: The role of software

Software will play a critical role throughout the Space Station Program. This presentation sets the stage and prompts participant interaction at the Software Issues Forum. The presentation is structured into three major topics: (1) an overview of the concept and status of the Space Station Program; (2) several charts designed to lay out the scope and role of software; and (3) information addressing the four specific areas selected for focus at the forum, specifically: software management, the software development environment, languages, and standards. NASA's current thinking is highlighted and some of the relevant critical issues are raised.

Hall, D.↗
NASA NTRS1986

An experiment in software reliability

The results of a software reliability experiment conducted in a controlled laboratory setting are reported. The experiment was undertaken to gather data on software failures and is one in a series of experiments being pursued by the Fault Tolerant Systems Branch of NASA Langley Research Center to find a means of credibly performing reliability evaluations of flight control software. The experiment tests a small sample of implementations of radar tracking software having ultra-reliability requirements and uses n-version programming for error detection, and repetitive run modeling for failure and fault rate estimation. The experiment results agree with those of Nagel and Skrivan in that the program error rates suggest an approximate log-linear pattern and the individual faults occurred with significantly different error rates. Additional analysis of the experimental data raises new questions concerning the phenomenon of interacting faults. This phenomenon may provide one explanation for software reliability decay.

Dunham, J. R.↗
NASA NTRS1985

Proceedings of Tenth Annual Software Engineering Workshop

Papers are presented on the following topics: measurement of software technology, recent studies of the Software Engineering Lab, software management tools, expert systems, error seeding as a program validation technique, software quality assurance, software engineering environments (including knowledge-based environments), the Distributed Computing Design System, and various Ada experiments.

Source record↗
NASA NTRS1985

DEASEL: An expert system for software engineering

For the past ten year, the Software Engineering Laboratory (SEL) has been collecting data on software projects carried out in the Systems Development Branch of the Flight Dynamics Division at NASA's Goddard Space Flight Center. Through a series of studies using this data, much knowledge has been gained on how software is developed within this environment. Two years ago work began on a software tool which would make this knowledge readily available to software managers. Ideally, the Dynamic Management Information Tool (DynaMITe) will aid managers in comparison across projects, prediction of a project's future, and assessment of a project's current state. This paper describes an effort to create the assessment portion of DynaMITe, called the DynaMITe Expert Advisor for the SEL (DEASEL).

Valett, J. D.↗
NASA NTRS1986

Army technology development. IBIS query. Software to support the Image Based Information System (IBIS) expansion for mapping, charting and geodesy

The Image Based Information System (IBIS) has been under development at the Jet Propulsion Laboratory (JPL) since 1975. It is a collection of more than 90 programs that enable processing of image, graphical, tabular data for spatial analysis. IBIS can be utilized to create comprehensive geographic data bases. From these data, an analyst can study various attributes describing characteristics of a given study area. Even complex combinations of disparate data types can be synthesized to obtain a new perspective on spatial phenomena. In 1984, new query software was developed enabling direct Boolean queries of IBIS data bases through the submission of easily understood expressions. An improved syntax methodology, a data dictionary, and display software simplified the analysts' tasks associated with building, executing, and subsequently displaying the results of a query. The primary purpose of this report is to describe the features and capabilities of the new query software. A secondary purpose of this report is to compare this new query software to the query software developed previously (Friedman, 1982). With respect to this topic, the relative merits and drawbacks of both approaches are covered.

Friedman, S. Z.↗