SELECTION OF A SET OF INDICATORS FOR ASSESSING THE OBJECT PERFORMANCE OF A FAULT

Abstract

The continuous complication of technical objects and the growth in the degree of automation of the control process bring to the fore the problem of optimal organization of the operation of complex technical objects. An important role is assigned to the definition of the state of objects, which, due to the influence of external and internal factors, changes over time. Technical diagnostics are responsible for resolving all issues related to determining the state of technical objects and the nature of its change over time. Technical diagnostics deals with the study of methods that determine the actual state of technical objects. This provision causes fundamental differences in the methods of research of technical objects used in the theory of reliability and in technical diagnostics. Possible malfunctions are divided into element malfunctions, which are defined as unacceptable quantitative changes in any parameter (characteristics) due to irreversible physical and chemical changes, and object malfunctions, which are interpreted as unacceptable quantitative changes in parameters (characteristics) or changes in structural relationships in the object. The process of determining the actual state of the object provides for the existence of a reasonable program and specified diagnostic algorithms. The diagnostic algorithm is a set of operations performed in a certain sequence in order to solve a specific diagnostic problem. The diagnostic program is a sequence of operations (algorithms) determined in time to establish the actual state of the object and the nature of its change. In this case, the initial data are the sequence of operations, the duration of each operation, the number of operations performed in parallel, and the required power of energy sources. Performance conditions can be formulated on the basis of an analysis of the model of the object being diagnosed or obtained on the basis of an experiment in the study of a real object. In this case, the performance conditions are defined either as restrictions on changes in dynamic and static characteristics or a set of object parameters, or as a requirement to perform specified functions in accordance with a certain logic. Analysis in the complex plane and the formulation of performance conditions as a requirement to find the roots of the transfer function in a given area make it relatively easy to make the transition to setting performance conditions in the time and frequency domains or in the area of controlled parameters. The health of an object is determined by its state. To assess the state of an object, it is necessary to plant it or perform its work functions, or respond to special control actions. In the first case, a so-called functional test will be carried out, in the second case, an assessment by parameters or characteristics. When checking for functioning, as a rule, there is no quantitative assessment and performance is determined by the compliance of the movements of the executive bodies, the amount (volume or weight) of the working fluid, products and positions of the switching bodies with the values set for the operating mode of the object. In addition, during the operation of the object, its performance can be assessed indirectly by the level of noise, the nature of the radiation, and the energy consumed. When evaluating the performance, as the parameters of the object, one can consider the parameters of the elements, the coefficients of the transfer function or the parameters of the dynamic links. When evaluating the performance of an object by characteristics, one can directly compare the actual characteristics with the reference ones, use integral estimates or compare individual indicators of static or dynamic characteristics. As indicators of time characteristics, quality indicators known from the theory of automatic control can be considered: decay time, rise of the first surge, delay, reaching a given level, period and number of oscillations, overshoot, etc. Frequency characteristics can be compared by maximum amplitude, bandwidth, frequencies cutoff and maximum. Parameters or characteristics can be evaluated separately at the facility or by comparing the response of the facility and an equivalent model to the same impact. In this case, it becomes necessary to build a model that is equivalent to an object based on controlled parameters or characteristics. Keywords: Technical diagnostics, object analysis, diagnostics, object health, resonant frequency, fault finding algorithms, decay time