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At least 1,153 records · Page 64

Real-time sensor data validation

This report describes the status of an on-going effort to develop software capable of detecting sensor failures on rocket engines in real time. This software could be used in a rocket engine controller to prevent the erroneous shutdown of an engine due to sensor failures which would otherwise be interpreted as engine failures by the control software. The approach taken combines analytical redundancy with Bayesian belief networks to provide a solution which has well defined real-time characteristics and well-defined error rates. Analytical redundancy is a technique in which a sensor's value is predicted by using values from other sensors and known or empirically derived mathematical relations. A set of sensors and a set of relations among them form a network of cross-checks which can be used to periodically validate all of the sensors in the network. Bayesian belief networks provide a method of determining if each of the sensors in the network is valid, given the results of the cross-checks. This approach has been successfully demonstrated on the Technology Test Bed Engine at the NASA Marshall Space Flight Center. Current efforts are focused on extending the system to provide a validation capability for 100 sensors on the Space Shuttle Main Engine.

Bickmore, Timothy W.↗

Online assessment of a distributed processor

ORT (Operational Readiness Test) software allows one engineer to test readiness of 64 minicomputers and their peripherals from single console. Software makes roll call of computers and peripherals via common data buffer to check readiness of system in morning "wake up" or at other important times. Subsystems are tested in parallel to save time. "Watchdog" terminates test of any system that does not respond in time, so one failed system does not halt test sequence. Entire rollcall is complete in about 15 minutes. Software is designed for Space Shuttle prelaunch checkout, but approach should interest users of similar equipment.

Ehrlich, L. F.↗

The environmental control and life support system advanced automation project

The objective of the ECLSS Advanced Automation project includes reduction of the risk associated with the integration of new, beneficial software techniques. Demonstrations of this software to baseline engineering and test personnel will show the benefits of these techniques. The advanced software will be integrated into ground testing and ground support facilities, familiarizing its usage by key personnel.

Dewberry, Brandon S.↗

Software Innovation in a Mission Critical Environment

Operating in mission-critical environments requires trusted solutions, and the preference for "tried and true" approaches presents a potential barrier to infusing innovation into mission-critical systems. This presentation explores opportunities to overcome this barrier in the software domain. It outlines specific areas of innovation in software development achieved by the Johnson Space Center (JSC) Engineering Directorate in support of NASA's major human spaceflight programs, including International Space Station, Multi-Purpose Crew Vehicle (Orion), and Commercial Crew Programs. Software engineering teams at JSC work with hardware developers, mission planners, and system operators to integrate flight vehicles, habitats, robotics, and other spacecraft elements for genuinely mission critical applications. The innovations described, including the use of NASA Core Flight Software and its associated software tool chain, can lead to software that is more affordable, more reliable, better modelled, more flexible, more easily maintained, better tested, and enabling of automation.

Fredrickson, Steven↗

Space Telecommunications Radio System (STRS) Application Repository Design and Analysis

The Space Telecommunications Radio System (STRS) Application Repository Design and Analysis document describes the STRS application repository for software-defined radio (SDR) applications intended to be compliant to the STRS Architecture Standard. The document provides information about the submission of artifacts to the STRS application repository, to provide information to the potential users of that information, and for the systems engineer to understand the requirements, concepts, and approach to the STRS application repository. The STRS application repository is intended to capture knowledge, documents, and other artifacts for each waveform application or other application outside of its project so that when the project ends, the knowledge is retained. The document describes the transmission of technology from mission to mission capturing lessons learned that are used for continuous improvement across projects and supporting NASA Procedural Requirements (NPRs) for performing software engineering projects and NASAs release process.

information retrieval↗

FLOP for FLAG Output Plotting

The Los Alamos hydrodynamics code, FLAG, is capable of dumping many types of output for many different variables in an array of formats. While some outputs are best viewed in a multidimensional engineering analysis visualization software, others are best viewed as 1-D “this versus that” curves. During development of a FLAG model, it is frequently required to quickly assess a model’s performance by reviewing such curves, and doing so may involve writing scripts repeatedly, adapting them each time to a specific model’s parameters. This report describes an application developed specifically to improve user efficiency in reviewing 1-D curve dumps from FLAG.

42 ENGINEERING↗

The Curiosity Mars Rover's Fault Protection Engine

The Curiosity Rover, currently operating on Mars, contains flight software onboard to autonomously handle aspects of system fault protection. Over 1000 monitors and 39 responses are present in the flight software. Orchestrating these behaviors is the flight software's fault protection engine. In this paper, we discuss the engine's design, responsibilities, and present some lessons learned for future missions.

flight software↗

A jet engine control problem for evaluating minimal design software

The problem of designing feedforward and feedback compensators to achieve a specified closed loop performance matrix is shown to reduce to a minimal design problem. Existing results for the F100 turbofan engine can be interpreted to yield the closed loop specifications for the associated control problem - and also a possible solution. All possible solutions can be enumerated by computing the kernel of a polynomial matrix. It is shown how this matrix can be obtained from the formulation of the minimal design problem.

Gejji, R. R.↗

Space shuttle orbital maneuvering system failure detection and identification software requirements (uncontrolled)

Candidate designs and their software implementation are presented for the Orbital Maneuvering System (OMS) Failure Detection and Identification (FDI) algorithms in the Redundance Management (RM) module of the Space Shuttle Guidance, Navigation, and Control (GN&C) software. The OMS engine FDI algorithm monitors OMS engine thrust performance, and the OMS actuator FDI algorithm monitors OMS gimbal actuator performance. The software functional requirements of the algorithms are described along with the objective of each algorithm. A list of the assumptions which have governed its design, input/output requirements, a functional description of the algorithm (including a functional block diagram), and input interface requirements are given. The HAL (the language of the space shuttle flight computer) software formulation of the algorithms is considered including structured flowcharts of the procedures, estimates of flight computer core storage and CPU time, and processing requirements. A glossary of the symbols used to define the software requirements and formulations is included.

Damario, L. A.↗

Position Papers for the ASCR Workshop on the Science of Scientific-Software Development and Use

Software is an increasingly important component in the pursuit of scientific discovery. Both its development and use are essential activities for many scientific teams. At the same time, very little scientific study has been conducted to understand, characterize, and improve the development and use of software for science. Computational science teams have diversified over time to include contributions from domain scientists who provide expertise in scientific and engineering disciplines, applied mathematicians and computer scientists who provide optimal algorithms and data structures, and software and data engineers who provide methodologies and tools adapted and adopted from other software domains. These diverse contributions have enabled tremendous advances in the pursuit of scientific discovery, even as models, computer architectures, and software environments have become more complicated. With this increasing diversity, we believe the next opportunity for qualitative improvement comes from applying the scientific method to understanding, characterizing, and improving how scientific software is developed and used. We believe that this pursuit requires expertise from computational scientists themselves, and from the cognitive and social sciences as well as the software engineering research community. As we look to increase the productivity and sustainability of the scientific-software-development-and-use cycle, a more systematic application of the scientific method to understand processes for software development and use will be a valuable tool to guide future work and result in more usable and sustainable software. This workshop will bring together computer scientists, software engineering researchers, computational scientists, applied mathematicians, social scientists, cognitive scientists, and others, to explore how we can conduct such systematic investigations, what can be learned, and how doing so will benefit the scientific enterprise. The workshop will be structured around a set of breakout sessions, with every attendee expected to participate actively in the discussions. Afterward, workshop attendees — from DOE, industry, and academia — will produce a report for ASCR that summarizes the findings of the workshop.

42 ENGINEERING↗

Analysis of Ada as a prototyping language

This paper examines the suitability of Ada as a language for developing software prototypes. The differences between software prototypes and traditional engineering prototypes are discussed; the approaches to software prototyping are identified. Ada's potential as a language for prototyping is evaluated according to the writability, expressiveness, and flexibility of the language; Ada is found to be inadequate as a prototyping language because it lacks writability and expressiveness. Possible approaches to improving the expressiveness of the language are discussed.

Holloway, C. Michael↗

User's Guide for the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS)

This report is a Users Guide for the NASA-developed Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) software, which is a transient simulation of a large commercial turbofan engine (up to 90,000-lb thrust) with a realistic engine control system. The software supports easy access to health, control, and engine parameters through a graphical user interface (GUI). C-MAPSS provides the user with a graphical turbofan engine simulation environment in which advanced algorithms can be implemented and tested. C-MAPSS can run user-specified transient simulations, and it can generate state-space linear models of the nonlinear engine model at an operating point. The code has a number of GUI screens that allow point-and-click operation, and have editable fields for user-specified input. The software includes an atmospheric model which allows simulation of engine operation at altitudes from sea level to 40,000 ft, Mach numbers from 0 to 0.90, and ambient temperatures from -60 to 103 F. The package also includes a power-management system that allows the engine to be operated over a wide range of thrust levels throughout the full range of flight conditions.

Frederick, Dean K.↗

User's Guide for the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS): Version 2

This report is a Users Guide for version 2 of the NASA-developed Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) software, which is a transient simulation of a large commercial turbofan engine (up to 90,000-lb thrust) with a realistic engine control system. The software supports easy access to health, control, and engine parameters through a graphical user interface (GUI). C-MAPSS v.2 has some enhancements over the original, including three actuators rather than one, the addition of actuator and sensor dynamics, and an improved controller, while retaining or improving on the convenience and user-friendliness of the original. C-MAPSS v.2 provides the user with a graphical turbofan engine simulation environment in which advanced algorithms can be implemented and tested. C-MAPSS can run user-specified transient simulations, and it can generate state-space linear models of the nonlinear engine model at an operating point. The code has a number of GUI screens that allow point-and-click operation, and have editable fields for user-specified input. The software includes an atmospheric model which allows simulation of engine operation at altitudes from sea level to 40,000 ft, Mach numbers from 0 to 0.90, and ambient temperatures from -60 to 103 F. The package also includes a power-management system that allows the engine to be operated over a wide range of thrust levels throughout the full range of flight conditions.

Liu, Yuan↗

Standardized development of computer software. Part 2: Standards

This monograph contains standards for software development and engineering. The book sets forth rules for design, specification, coding, testing, documentation, and quality assurance audits of software; it also contains detailed outlines for the documentation to be produced.

Tausworthe, R. C.↗

Software for Preprocessing Data From Rocket-Engine Tests

Three computer programs have been written to preprocess digitized outputs of sensors during rocket-engine tests at Stennis Space Center (SSC). The programs apply exclusively to the SSC E test-stand complex and utilize the SSC file format. The programs are the following: (1) Engineering Units Generator (EUGEN) converts sensor-output-measurement data to engineering units. The inputs to EUGEN are raw binary test-data files, which include the voltage data, a list identifying the data channels, and time codes. EUGEN effects conversion by use of a file that contains calibration coefficients for each channel. (2) QUICKLOOK enables immediate viewing of a few selected channels of data, in contradistinction to viewing only after post-test processing (which can take 30 minutes to several hours depending on the number of channels and other test parameters) of data from all channels. QUICKLOOK converts the selected data into a form in which they can be plotted in engineering units by use of Winplot. (3) EUPLOT provides a quick means for looking at data files generated by EUGEN without the necessity of relying on the PVWAVE based plotting software.

Cheng, Chiu-Fu↗

CiteSoft_Py

There is a need to provide a way for dev-users (Scientists, Engineers, and other Software Developers) to get credit (citations) when they contribute to an important software package - particularly a large package that is already established. Various solutions (including cross package) solutions do exist, but a simple standard format that can work between multiple packages and multiple languages in a modular way is not widely available. CiteSoft_py is a python implementation of CiteSoft. CiteSoft is a plain text standard consisting of a format and a protocol that exports the citations for the end-users for whichever softwares they have used. CiteSoft has been designed so that software dev-users can rely upon it regardless of coding language or platform, and even for cases where multiple codes are working in a coupled manner. The CiteSoft_py implementation includes python decorators to make wrappers for facile use. The purpose is that when dev-users (scientists, engineers and professional programmers) contribute to a collaborative software project, that the appropriate citations (e.g., journal article, conference proceeding) are provided to the end-user. The end-user does not need to know how to use a command line interface, API, etc.

Savara, Aditya↗

Building Safer Systems With SpecTRM

System safety, an integral component in software development, often poses a challenge to engineers designing computer-based systems. While the relaxed constraints on software design allow for increased power and flexibility, this flexibility introduces more possibilities for error. As a result, system engineers must identify the design constraints necessary to maintain safety and ensure that the system and software design enforces them. Safeware Engineering Corporation, of Seattle, Washington, provides the information, tools, and techniques to accomplish this task with its Specification Tools and Requirements Methodology (SpecTRM). NASA assisted in developing this engineering toolset by awarding the company several Small Business Innovation Research (SBIR) contracts with Ames Research Center and Langley Research Center. The technology benefits NASA through its applications for Space Station rendezvous and docking. SpecTRM aids system and software engineers in developing specifications for large, complex safety critical systems. The product enables engineers to find errors early in development so that they can be fixed with the lowest cost and impact on the system design. SpecTRM traces both the requirements and design rationale (including safety constraints) throughout the system design and documentation, allowing engineers to build required system properties into the design from the beginning, rather than emphasizing assessment at the end of the development process when changes are limited and costly.System safety, an integral component in software development, often poses a challenge to engineers designing computer-based systems. While the relaxed constraints on software design allow for increased power and flexibility, this flexibility introduces more possibilities for error. As a result, system engineers must identify the design constraints necessary to maintain safety and ensure that the system and software design enforces them. Safeware Engineering Corporation, of Seattle, Washington, provides the information, tools, and techniques to accomplish this task with its Specification Tools and Requirements Methodology (SpecTRM). NASA assisted in developing this engineering toolset by awarding the company several Small Business Innovation Research (SBIR) contracts with Ames Research Center and Langley Research Center. The technology benefits NASA through its applications for Space Station rendezvous and docking. SpecTRM aids system and software engineers in developing specifications for large, complex safety critical systems. The product enables engineers to find errors early in development so that they can be fixed with the lowest cost and impact on the system design. SpecTRM traces both the requirements and design rationale (including safety constraints) throughout the system design and documentation, allowing engineers to build required system properties into the design from the beginning, rather than emphasizing assessment at the end of the development process when changes are limited and costly.

Source record↗

Evaluation of the efficiency and fault density of software generated by code generators

Flight computers and flight software are used for GN&C (guidance, navigation, and control), engine controllers, and avionics during missions. The software development requires the generation of a considerable amount of code. The engineers who generate the code make mistakes and the generation of a large body of code with high reliability requires considerable time. Computer-aided software engineering (CASE) tools are available which generates code automatically with inputs through graphical interfaces. These tools are referred to as code generators. In theory, code generators could write highly reliable code quickly and inexpensively. The various code generators offer different levels of reliability checking. Some check only the finished product while some allow checking of individual modules and combined sets of modules as well. Considering NASA's requirement for reliability, an in house manually generated code is needed. Furthermore, automatically generated code is reputed to be as efficient as the best manually generated code when executed. In house verification is warranted.

Schreur, Barbara↗