UML-based specification, validation, and log-file based verification of the Orion Pad Abort Software

This paper described the first end to end application of a novel light weight formal specification, validation, and verification technique. The technique is novel is two aspects. First, it uses an intuitive, familiar, and diagrammatic notation for formal specification, a notation that being Turing equivalent and supports the capture of real-life requirements. Second, the technique includes a computer aided approach for validating the correctness of requirements early in the development process, allowing sufficient time for the correction of ambiguous and underspecified requirements. In the verification phase the technique is based on off-line verification using log-files. This approach scales well and is applicable to almost every mission critical system, including real-time systems. The paper describes the application of this technique towards the specification, validation, and verification of the Pad Abort subsystem of NASA's Orion mission.Approved for public release; distribution is unlimited

The Application of V&V within Reuse-Based Software Engineering

Verification and Validation (V&V) is performed during application development for many systems, especially safety-critical and mission-critical systems. The V&V process is intended to discover errors as early as possible during the development process. Early discovery is important in order to minimize the cost and other impacts of correcting these errors. In reuse-based software engineering, decisions on the requirements, design and even implementation of domain assets can can be made prior to beginning development of a specific system. in order to bring the effectiveness of V&V to bear within reuse-based software engineering. V&V must be incorporated within the domain engineering process

Software Reliability through Theorem Proving

Improving software reliability of mission-critical systems is widely recognised as one of the major challenges. Early detection of errors in software requirements, designs and implementation, need rigorous verification and validation techniques. Several techniques comprising static and dynamic testing approaches are used to improve reliability of mission critical software; however it is hard to balance development time and budget with software reliability. Particularly using dynamic testing techniques, it is hard to ensure software reliability, as exhaustive testing is not possible. On the other hand, formal verification techniques utilise mathematical logic to prove correctness of the software based on given specifications, which in turn improves the reliability of the software. Theorem proving is a powerful formal verification technique that enhances the software reliability for missioncritical aerospace applications. This paper discusses the issues related to software reliability and theorem proving used to enhance software reliability through formal verification technique, based on the experiences with STeP tool, using the conventional and internationally accepted methodologies, models, theorem proving techniques available in the tool without proposing a new model.Defence Science Journal, 2009, 59(3), pp.314-317, DOI:http://dx.doi.org/10.14429/dsj.59.152

Model Transformation for a System of Systems Dependability Safety Case

Software plays an increasingly larger role in all aspects of NASA's science missions. This has been extended to the identification, management and control of faults which affect safety-critical functions and by default, the overall success of the mission. Traditionally, the analysis of fault identification, management and control are hardware based. Due to the increasing complexity of system, there has been a corresponding increase in the complexity in fault management software. The NASA Independent Validation & Verification (IV&V) program is creating processes and procedures to identify, and incorporate safety-critical software requirements along with corresponding software faults so that potential hazards may be mitigated. This Specific to Generic ... A Case for Reuse paper describes the phases of a dependability and safety study which identifies a new, process to create a foundation for reusable assets. These assets support the identification and management of specific software faults and, their transformation from specific to generic software faults. This approach also has applications to other systems outside of the NASA environment. This paper addresses how a mission specific dependability and safety case is being transformed to a generic dependability and safety case which can be reused for any type of space mission with an emphasis on software fault conditions

Technique Integration for Requirements Assessment

In determining whether to permit a safety-critical software system to be certified and in performing independent verification and validation (IV&V) of safety- or mission-critical systems, the requirements traceability matrix (RTM) delivered by the developer must be assessed for accuracy. The current state of the practice is to perform this work manually, or with the help of general-purpose tools such as word processors and spreadsheets Such work is error-prone and person-power intensive. In this paper, we extend our prior work in application of Information Retrieval (IR) methods for candidate link generation to the problem of RTM accuracy assessment. We build voting committees from five IR methods, and use a variety of voting schemes to accept or reject links from given candidate RTMs. We report on the results of two experiments. In the first experiment, we used 25 candidate RTMs built by human analysts for a small tracing task involving a portion of a NASA scientific instrument specification. In the second experiment, we randomly seeded faults in the RTM for the entire specification. Results of the experiments are presented

A Framework for Performing V&V within Reuse-Based Software Engineering

Verification and validation (V&V) is performed during application development for many systems, especially safety-critical and mission-critical systems. The V&V process is intended to discover errors, especially errors related to critical processing, as early as possible during the development process. Early discovery is important in order to minimize the cost and other impacts of correcting these errors. In order to provide early detection of errors, V&V is conducted in parallel with system development, often beginning with the concept phase. In reuse-based software engineering, however, decisions on the requirements, design and even implementation of domain assets can be made prior to beginning development of a specific system. In this case, V&V must be performed during domain engineering in order to have an impact on system development. This paper describes a framework for performing V&V within architecture-centric, reuse-based software engineering. This framework includes the activities of traditional application-level V&V, and extends these activities into domain engineering and into the transition between domain engineering and application engineering. The framework includes descriptions of the types of activities to be performed during each of the life-cycle phases, and provides motivation for the activities

Application of flight systems methodologies to the validation of knowledge-based systems

Flight and mission-critical systems are verified, qualified for flight, and validated using well-known and well-established techniques. These techniques define the validation methodology used for such systems. In order to verify, qualify, and validate knowledge-based systems (KBS's), the methodology used for conventional systems must be addressed, and the applicability and limitations of that methodology to KBS's must be identified. The author presents an outline of how this approach to the validation of KBS's is being developed and used at the Dryden Flight Research Facility of the NASA Ames Research Center

Technology for the Future: In-Space Technology Experiments Program, part 2

The purpose of the Office of Aeronautics and Space Technology (OAST) In-Space Technology Experiments Program In-STEP 1988 Workshop was to identify and prioritize technologies that are critical for future national space programs and require validation in the space environment, and review current NASA (In-Reach) and industry/ university (Out-Reach) experiments. A prioritized list of the critical technology needs was developed for the following eight disciplines: structures; environmental effects; power systems and thermal management; fluid management and propulsion systems; automation and robotics; sensors and information systems; in-space systems; and humans in space. This is part two of two parts and contains the critical technology presentations for the eight theme elements and a summary listing of critical space technology needs for each theme

Approaches to the verification of rule-based expert systems

Expert systems are a highly useful spinoff of artificial intelligence research. One major stumbling block to extended use of expert systems is the lack of well-defined verification and validation (V and V) methodologies. Since expert systems are computer programs, the definitions of verification and validation from conventional software are applicable. The primary difficulty with expert systems is the use of development methodologies which do not support effective V and V. If proper techniques are used to document requirements, V and V of rule-based expert systems is possible, and may be easier than with conventional code. For NASA applications, the flight technique panels used in previous programs should provide an excellent way to verify the rules used in expert systems. There are, however, some inherent differences in expert systems that will affect V and V considerations

Gateway Modeling and Simulation Plan

This plan institutes direction across the Gateway Program and the Element Projects to ensure that Cross Program M&S are produced in a manner that (1) generate the artifacts required for NASA-STD-7009 compliance, (2) ensures interoperability of M&S exchanged and integrated across the program and, (3) drives integrated development efforts to provide cross-domain integrated simulation of the Gateway elements, space environment, and operational scenarios. This direction is flowed down via contractual enforcement to prime contractors and includes both the GMS requirements specified in this plan and the NASASTD- 7009 derived requirements necessary for compliance. Grounding principles for management of Gateway Models and Simulations (M&S) are derived from the Columbia Accident Investigation Board (CAIB) report and the Diaz team report, A Renewed Commitment to Excellence. As an outcome of these reports, and in response to Action 4 of the Diaz team report, the NASA Standard for Models and Simulations, NASA-STD-7009 was developed. The standard establishes M&S requirements for development and use activities to ensure proper capture and communication of M&S pedigree and credibility information to Gateway program decision makers. Through the course of the Gateway program life cycle M&S will be heavily relied upon to conduct analysis, test products, support operations activities, enable informed decision making and ultimately to certify the Gateway with an acceptable level of risk to crew and mission. To reduce risk associated with M&S influenced decisions, this plan applies the NASA-STD-7009 requirements to produce the artifacts that support credibility assessments and ensure the information is communicated to program management