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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Detecting Hidden Failure Modes in Critical, Embedded Software

This experience report describes a method that has been used successfully to detect hidden failure modes in critical, embedded spacecraft software. The method is an adaptation of an earlier, controversial approach called failure modes and effects analysis. The adapted method was found to be well-suited to identifying latent software design weaknesses involving complex system interactions and dependencies in the two applications described here. This experience may be useful for other high-integrity software systems in which the possibility of hidden failure modes is a major concern.

detecting software failure design analysis↗
NASA NTRS1993

The Cassini spacecraft: Object oriented flight control software

The Cassini Attitude and Articulation Control Subsystem (AACS) is responsible for determining and controlling the spacecraft attitude including instrument pointing, antenna pointing, and thrust vector pointing during velocity change maneuvers. The 12 year mission life, long round-trip light time, and extended periods of coast without continuous ground control drive the AACS flight software design in the directions of autonomy, fault tolerance, and modularity to accommodate planned upgrades in flight. The Cassini AACS Flight Software is depicted in increasing levels of detail using a Context Diagram, Architecture Diagrams (i.e., Dependency Diagrams), an Object Diagram for each object, and a Statechart (i.e., State Transition Diagram) for each object. The detail contained in the diagrams is enhanced and refined during the Requirements and Design Phases of both Subsystem and Software Development. Examples of all the diagrams as well as the criteria for object selection, the advantages of statecharts, and the ease of modifying the design to accommodate changes in scope are described.

Hackney, John C.↗
NASA NTRS1996

Identification, Uncertainty Characterization and Robust Control Synthesis Applied to Large Flexible Structures Control

This paper demonstrates an approach to frequency domain identification for the explicit purpose of designing robust H(infinity) controllers. The approach transforms raw experimental data into a plant set estimate directly usable by modern robust control design software(e.g., Matlab Robust Control Toolboxes [11][2]). A key issue in control design from raw data is the question of whether the controller will work when applied to the true system. The main feature fo this approach is that the resulting controller in guaranteed to work as designed(when applied to the true system) to a prescribed statistical confidence. While the overall methodology addresses key theoretical issues, it has at the same time been specifically designed to support practical implementations. A simulation example is included to demonstrate the overall approach.

software↗
NASA NTRSDate not supplied

Clinical Decision Support For Exploration Space Flight: Software Augmentation To Enhance Progressively Earth-Independent Medical Operations

This panel identifies the challenges of supporting medical events in deep space using integrated systems software to augment existing capabilities during increasingly Earth-independent missions where an asynchronous communication environment becomes routine. An interdisciplinary team of software designers, physicians, human factors engineers, and computational modelers applied their respective expertise to develop a roadmap for supporting the crew making medical decisions in more autonomous fashion with time-delayed ground support. The first presentation describes predictive modeling implemented to assist medical system design and address risk reduction using robust clinical decision support software. The second presentation details how operational and environmental challenges guide assumptions and, in turn, by what means requirements for medical decision-making in deep space are derived. The third presentation describes and defines the skills and capabilities an exploration spaceflight medical officer will need to perform effectively during extended-duration spaceflight missions. The fourth presentation covers the potential models and function of the software element for supporting clinical decisions. The final presentation covers how these elements may work together with ground support to provide comprehensive care despite deep space travel's extreme challenges and limitations.

Dana Levin↗
NASA NTRS2023

Considerations for Software Fault Prevention and Tolerance

Mission or safety-critical spaceflight systems should be developed to both reduce the likelihood of software faults pre-flight and to detect/mitigate the effects of software errors should they occur in-flight. New data is available that categorizes software errors from significant historic spaceflight software incidents with implications and considerations to better develop and design software to both minimize and tolerate these most likely software failures.

Avionics↗
NASA NTRS1992

Design of a nickel-hydrogen battery simulator for the NASA EOS testbed

The hardware and software design of a nickel-hydrogen (Ni-H2) battery simulator (BS) with application to the NASA Earth Observation System (EOS) satellite is presented. The battery simulator is developed as a part of a complete testbed for the EOS satellite power system. The battery simulator involves both hardware and software components. The hardware component includes the capability of sourcing and sinking current at a constant programmable voltage. The software component includes the capability of monitoring the battery's ampere-hours (Ah) and programming the battery voltage according to an empirical model of the nickel-hydrogen battery stored in a computer.

Gur, Zvi↗
NASA NTRS1984

A research program in active control/aeroelasticity in the JIAFS at NASA Langley Research Center

A control law synthesis methodology for multifunctional active control system to satisfy root-mean-square load and response constraints as well as to meet stability robustness requirements at plant input and output was developed. Modern control theory, singular value analysis and optimization techniques were utilized. All stability and response derivative expressions were derived analytically for sensitivity study. The software is incorporated as an update to the AB/LAD general control design software package PADLOCS.

Whitesides, J. L.↗
NASA NTRS1988

COSPAS/SARSAT 406-MHz emergency beacon digital controller

The digital control portion of a low-cost 406-MHz COSPAS/SARSAT emergency beacon has been designed and breadboarded at the NASA Lewis Research Center. This report discusses the requirements and design tradeoffs of the digital controller and describes the hardware and software design, which is available only to United States citizens and companies.

Ivancic, William D.↗
NASA NTRS1990

Flight Dynamics Analysis System

Flight Dynamics Analysis System (FDAS) collection of computer programs provides environment for configuration and study of Ada software. Designed to support flight-dynamics research and analysis activities concerning software models, algorithms, and techniques used within flight Dynamics Division at Goddard Space Flight Center. Assists analysts and programmers in building, testing, and evaluating applications software by providing integrated support system for modification and reconfiguration of software. Includes capability of assembling reusable software components into applications programs, and reconfiguring assembled program after partially or fully completed. Developed in Ada for use on DEC VAX computer operating under VMS 4.3 or higher and version 1.3 or higher of VAX Ada Compilation System (ACS).

Tasaki, Keiji↗
NASA NTRS1991

The walking robot project

A walking robot was designed, analyzed, and tested as an intelligent, mobile, and a terrain adaptive system. The robot's design was an application of existing technologies. The design of the six legs modified and combines well understood mechanisms and was optimized for performance, flexibility, and simplicity. The body design incorporated two tripods for walking stability and ease of turning. The electrical hardware design used modularity and distributed processing to drive the motors. The software design used feedback to coordinate the system and simple keystrokes to give commands. The walking machine can be easily adapted to hostile environments such as high radiation zones and alien terrain. The primary goal of the leg design was to create a leg capable of supporting a robot's body and electrical hardware while walking or performing desired tasks, namely those required for planetary exploration. The leg designers intent was to study the maximum amount of flexibility and maneuverability achievable by the simplest and lightest leg design. The main constraints for the leg design were leg kinematics, ease of assembly, degrees of freedom, number of motors, overall size, and weight.

Williams, P.↗
NASA NTRS1992

Problem-Solving Software

CBR Express software solves problems by adapting sorted solutions to new problems specified by a user. It is applicable to a wide range of situations. The technology was originally developed by Inference Corporation for Johnson Space Center's Advanced Software Development Workstation. The project focused on the reuse of software designs, and Inference used CBR as part of the ACCESS prototype software. The commercial CBR Express is used as a "help desk" for customer support, enabling reuse of existing information when necessary. It has been adopted by several companies, among them American Airlines, which uses it to solve reservation system software problems.

Source record↗
NASA NTRS2003

Obtaining the Greatest Scientific Benefit from Observational Platforms by Consideration of the Relative Benefit of Observations

One of the current trends in spacecraft software design is to increase the autonomy of onboard flight and science software. This is especially true when real-time observations may affect the observation schedule of a mission. For many science missions, such as those conducted by the Swift Burst Alert Telescope, the ability of the spacecraft to autonomously respond in real-time to unpredicted science events is crucial for mission success. We apply utility theory within resource management middleware to optimize the real-time performance of application software and achieve maximum system level benefit. We then explore how this methodology can be extended to manage both software and observational resources onboard a spacecraft to achieve the best possible observations.

Chelberg, David↗
NASA NTRS2013

Installation of TVC Actuators in a Two Axis Inertial Load Simulator Test Stand

This paper is about the installation of Space Shuttle Main Engines (SSME) actuators in the new Two Axis Inertial Load Simulator (ILS) at MSFC. The new test stand will support the core stage of the Space Launch System (SLS). Because of the unique geometry of the new test stand standard actuator installation procedures will not work. I have been asked to develop a design on how to install the actuators into the new test stand. After speaking with the engineers and technicians I have created a possible design solution. Using Pro Engineer design software and running my own stress calculations I have proven my design is feasible. I have learned how to calculate the stresses my design will see from this task. From the calculations I have learned I have over built the apparatus. I have also expanded my knowledge of Pro Engineer and was able to create a model of my idea.

Dziubanek, Adam↗
NASA NTRS1990

An experimental evaluation of software redundancy as a strategy for improving reliability

The strategy of using multiple versions of independently developed software as a means to tolerate residual software design faults is suggested by the success of hardware redundancy for tolerating hardware failures. Although, as generally accepted, the independence of hardware failures resulting from physical wearout can lead to substantial increases in reliability for redundant hardware structures, a similar conclusion is not immediate for software. The degree to which design faults are manifested as independent failures determines the effectiveness of redundancy as a method for improving software reliability. Interest in multi-version software centers on whether it provides an adequate measure of increased reliability to warrant its use in critical applications. The effectiveness of multi-version software is studied by comparing estimates of the failure probabilities of these systems with the failure probabilities of single versions. The estimates are obtained under a model of dependent failures and compared with estimates obtained when failures are assumed to be independent. The experimental results are based on twenty versions of an aerospace application developed and certified by sixty programmers from four universities. Descriptions of the application, development and certification processes, and operational evaluation are given together with an analysis of the twenty versions.

Eckhardt, Dave E., Jr.↗
NASA NTRS1991

An experimental evaluation of software redundancy as a strategy for improving reliability

The strategy of using multiple versions of independently developed software as a means to tolerate residual software design faults is suggested by the success of hardware redundancy for tolerating hardware failires. Although, as generally accepted, the independence of hardware failures resulting from physical wearout can lead to substantial increases in reliability for redundant hardware structures, a similar conclusion is not immediate for software. The degree to which design faults are manifested as independent failures determines the effectiveness of redundancy as a method for improving software reliability. Interest in multi-version software centers on whether it provides an adequate measure of increased reliability to warrant its use in critical applications. The effectiveness of multi-version software is studied by comparing estimates of the failure probabilities of these systems with the failure probabilities of single versions. The estimates are obtained under a model of dependent failures and compared with the estimates obtained when failures are assumed to be independent. The experimental results are based on twenty versions of an aerospace application developed and certified by sixty programmers from four universities. Descriptions of the application, development and certifications processes, and operational evaluation are given together with an analysis of the twenty versions.

Eckhardt, Dave E.↗
NASA NTRS1979

The design of relatively machine-independent code generators

Two complementary approaches were investigated. In the first approach software design techniques were used to design the structure of a code generator for Halmat. The major result was the development of an intermediate code form known as 7UP. The second approach viewed the problem as one in providing a tool to the code generator programmer. The major result was the development of a non-procedural, problem oriented language known as CGGL (Code Generator Generator Language).

Noonan, R. E.↗
NASA NTRS1989

NASA/NBS (National Aeronautics and Space Administration/National Bureau of Standards) standard reference model for telerobot control system architecture (NASREM)

The document describes the NASA Standard Reference Model (NASREM) Architecture for the Space Station Telerobot Control System. It defines the functional requirements and high level specifications of the control system for the NASA space Station document for the functional specification, and a guideline for the development of the control system architecture, of the 10C Flight Telerobot Servicer. The NASREM telerobot control system architecture defines a set of standard modules and interfaces which facilitates software design, development, validation, and test, and make possible the integration of telerobotics software from a wide variety of sources. Standard interfaces also provide the software hooks necessary to incrementally upgrade future Flight Telerobot Systems as new capabilities develop in computer science, robotics, and autonomous system control.

Albus, James S.↗
NASA NTRS1986

An expert system prototype for aiding in the development of software functional requirements for NASA Goddard's command management system: A case study and lessons learned

At NASA Goddard, the role of the command management system (CMS) is to transform general requests for spacecraft opeerations into detailed operational plans to be uplinked to the spacecraft. The CMS is part of the NASA Data System which entails the downlink of science and engineering data from NASA near-earth satellites to the user, and the uplink of command and control data to the spacecraft. Presently, it takes one to three years, with meetings once or twice a week, to determine functional requirements for CMS software design. As an alternative approach to the present technique of developing CMS software functional requirements, an expert system prototype was developed to aid in this function. Specifically, the knowledge base was formulated through interactions with domain experts, and was then linked to an existing expert system application generator called 'Knowledge Engineering System (Version 1.3).' Knowledge base development focused on four major steps: (1) develop the problem-oriented attribute hierachy; (2) determine the knowledge management approach; (3) encode the knowledge base; and (4) validate, test, certify, and evaluate the knowledge base and the expert system prototype as a whole. Backcasting was accomplished for validating and testing the expert system prototype. Knowledge refinement, evaluation, and implementation procedures of the expert system prototype were then transacted.

Liebowitz, Jay↗