Organization features of functional diagnosis of a control computerwith improved survivability

Purpose. Today, the reliability of protection of mission critical objects and objects of increased risk is achieved by applying integrated safety systems, with the integration of subsystems based on control computers. Improvement of survivability of special purpose computers is a critical task that could be solved using the computers with the property of structural stability. Practical realization of such computer is connected with the task of its functional diagnosis and further functional adjustment. This article describes the process of functional diagnosis of structurally stable control computer as a functional system that is fundamentally different from the traditional control of a personal computer made by the known self-checking programs. Methods. To solve the task of functional diagnosis the article offers a mathematical model of test check that may become the basis of functional diagnosis of a control computer. Besides, based on the proposed mathematical model, possible outcomes of the test are analyzed. Results. Analysis of the proposed mathematical model defined the variants of how to minimize the risks of categories I and II, i.e. how to transfer faulty functions to a set of fault-free functions (customer's risk) and to transfer fault-free functions to a set of faulty ones (producer's risk), that is achieved by using a diagnosis practice of “promotion" that is standard for computers. The point is to find an operable “core" - a set of basic functions that help to diagnose the remaining functions of the computer's system of commands. I.e. the “core" with any detected defect is not allowed for further functioning, and a fault-free “core" can serve as rather reliable mean of control. When using this practice, the norm of a single test does not guarantee there is no risk of category I, that explains the common practice of check of each function of the command system by a sufficient sequence of test checks, and the risk of category II does not grow. Conclusion. The proposed model of a functional diagnosis test check made it possible to form the strategy to construct this process for a structurally stable control computer, namely to implement several particular tasks such as: to separate as a specific the task of identification of an operable “core" as a probable cause of risk of category I, that serves as a source of risk of category II; to perform sequential diagnosis of the remaining part of functions as in computing environment with a developed property of slow degradation of functions; to optimize an extending sequence of test checks for each function reducing the risk of category I, irretrievably leading to the growth of time control that is deficit for a pre-staged self-checking; that is also aimed at the adjustment to the current f-state; to proceed with testing in case of negative results using another software implementation to reduce risk of category II; to develop special procedure to substantiate the duration of testing of each function of control computers.

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