System integrated fault-tree analysis methods (SIFTAN)
First Claim
1. A method of performing integrated fault-tree analysis on a software controlled system, said software controlled system employing a specific hardware configuration which hardware configuration is selectively operated by means of programmed software comprising the steps performed by a computer of:
- predicting a critical system output condition manifesting a top-level-event,determining from that predicted condition a set of prior system conditions which caused said event,modifying the system response upon detection of an unblocked patch to said event according to said set of prior system conditions.
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Abstract
The subject invention employs a system integrated fault-tree analysis (SIFTAN) which has the unique ability to detect all latent hardware and software design defects that could cause unanticipated critical failure of a complex software controlled electronic system. This new approach modifies and then integrates two existing system analysis techniques-namely, hardware fault-tree analysis (HFTA) and software fault-tree analysis (SFTA). The resultant integrated technique is identified as SIFTAN for system integrated fault-tree analysis. Through its integrated hardware/software scope and its critical failure focus, SIFTAN has unique potential to solve the essential analytical limitation behind the software reliability problem. The system exceeds the scope of all current system analysis techniques by providing a system free from all potential critical specification hardware or software design errors. The system accomplishes the above-noted objects by performing fault tree analysis with respect to the contents of a dynamic "stack of contradiction parameters" and then superimposing the modified hardware and software fault trees onto each other. The super position is accomplished by automatically branching from the software to a specified fault tree hardware whenever hardware could result in a critical system output. It is important to indicate that the SIFTAN system is applied with great advantages to early conceptual levels of system design in addition to its certification of the final design implementation.
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Citations
25 Claims
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1. A method of performing integrated fault-tree analysis on a software controlled system, said software controlled system employing a specific hardware configuration which hardware configuration is selectively operated by means of programmed software comprising the steps performed by a computer of:
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predicting a critical system output condition manifesting a top-level-event, determining from that predicted condition a set of prior system conditions which caused said event, modifying the system response upon detection of an unblocked patch to said event according to said set of prior system conditions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 23)
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10. A method of performing an integrated fault-tree analysis on a digital software controlled system said software controlled system employing a specific hardware configuration which hardware configuration is selected to operate under control of programmed software comprising the steps performed by a computer of:
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defining a critical system output condition specifying a top-level-system event, forming a set of contradiction parameters indicative of the other top-level-system conditions, parsing the system software for a program statement which sets the defined top level system event, retrieving a generic fault-tree template for said program statement to identify which inputs to said program statement sets said top-level-event, examining said fault tree for contradictions according to said set of formed contradiction parameters to determine which inputs do not lead to said top-level-event, and which inputs do lead to said top-level-event, eliminating all inputs found which do not lead to said event, replacing all inputs which lead to said event for defining a new top-level-event and continuing said steps commencing with said step of parsing the system software until all inputs are eliminated. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 21, 22, 24, 25)
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19. ORing other parameters in said set with other simultaneously occurring events, and
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20. separately analyzing said OR'"'"'ed combinations apart from said AND'"'"'ed combinations.
Specification