ŎƬ˘˹ŘǚŘ ʊǔDŽ ȭŘ ǘɁʁ˘˿ʊǜŘȭǔƬ ˘ Řʁǜ˿ǘˁȦˁ ȭŘ ˹ŘʁˁȭǘŘƋǒ ǚǔƋƬȭƋǖǔ ,ʁƬŘǜǔ˸Ƭ ,ɁȧȧɁȭʊ ʢȭŘȭǔƬ ŘˁǜɁʁʊǜ˹Ř ʯƖ1
. IntroductionDiagnostics of analog systems is currently a wide domain with numerous applications, closely related to the types of analyzed objects. With the increasing number of such systems (including mechanical and electronic elements), the set of usable approaches also increases. Contrary to the digital object, its analog counterpart is characterized by the continuous transmission and processing of information. Therefore the system may also be in the infinite number of states, generating continuous signals. This makes the diagnostics of analog systems especially difficult. The most popular approaches used in the domain belong to Artificial Intelligence (AI). Their advantages include the autonomous operation (without the input of the human operator), high accuracy with generalization abilities and (in most cases) the ability to update knowledge through the additional learning procedure. Disadvantages include the dependency of the acquired diagnostic knowledge on the available data (use cases) presented during the training of the diagnostic module. Sometimes explanation of the reasoning process (i.e. how the premises were used to draw conclusions) is required. The most popular diagnostic methods, exploited in practice, are Artificial Neural Networks (ANN) [1,2]. This paper presents the taxonomy, structural and operational details of ANN used for the diagnostic purposes. The structure of the paper is as follows. Section 2 presents diagnostic principles important from the AI-application point of view. In Section 3 the generic diagnostic architecture is introduced with the focus on internal modules. Section 4 covers the ANN work regime from the diagnostic point of view. In Section 5 the main architectures of ANN with their applications are presented. Section 6 presents diagnostics of the 5 th order lowpass filter using the RBF ANN-based classifier. In Section 7 summary and future prospects of the discussed ANN are provided.
Aims of the diagnosticsDiagnostics is aimed at determining the actual state of the analyzed System Under Test -SUT, based on the observations of the measured signals y(t) being responses to the known excitation x(t). Similarly to the medical and veterinary diagnostics, in technical sciences non-invasive approaches are preferred, where the information about the system's behavior is available only through the input and output (accessible and partially accessible) nodes (with the maximum set of nodes being hidden, i.e. inaccessible). Therefore the diagnostic system is expected to establish relations (in the form of the unknown function f()) between the observable features of output signals and configuration of parameters p defining the SUT's work regime [1]. The latter can be based on the human expert's experience or the mathematical description of the system. Alternatively, simulations of the SUT model may provide the information about how it works and how changes in parameters influence behavior o...