The algorithm of fuzzification of the input value of fuzzy system of automatic control of the executive body of shearer on coal seam hypsometry

Abstract

Purpose. The purpose is to create an informative criterion that reveals violations of the regularity of changes in time of the stator current of the cutting drive motor of a shearer at the beginning of cutting by the executive body of the breed near the roof of the seam. Also, the purpose of the paper is to create a fuzzification algorithm for this informative criterion based on the analysis of the coincidence of function graphs that approximate the change in time of the low-frequency component of the stator current at different time intervals of moving upward of the executive body of the shearer. The methodology of research consists is to establish the statistical characteristics of the stator current of the cutting drive motor of a shearer, which are sensitive to the violation of the regularity of change in time of the low-frequency component of the current of the drive motor of a cutting drive because of the beginning of cutting by the executive body of the breed near the roof of the seam, and also to adapt these characteristics for use as term membership functions. Findings. The appearance of rock cutting at the second stage of a two-stage step-by-step movement of the executive body of the shearer with a modified cutting resistance compared to coal by 14% or more leads to a significant change in the degree of divergence of deviations of the stator current of cutting drive motor separately in the first and second stages of executive body movement in the range of frequencies from 3.12 to 6.25 Hz. This allowed as a numerical informative criterion to use the degree of divergence of the maximum values of the curves that approximate the time variation of the stator current of the cutting drive motor of shearer in the frequency range from 3.12 to 6.25 Hz at certain stages of moving upward of the executive body. It was also found that for various combinations of coal and rock properties, at fuzzification of a numerical informative criterion of mode of material destruction near the roof of the seam, based on approximation of histograms of criterion values distribution, the most acceptable approximating functions, providing the relative deviation of function values from histogram frequencies not more than 10%, are the polynomials of fifth order. The originality consists in using to identify the modes of material destruction near the roof of the seam the result of analyzing the degree of violation of the regularity of changes in time of the low-frequency component of the stator current of the cutting drive motor on the separate time intervals of moving upward of the executive body. At the same time, the algorithm of fuzzification of a numerical informative criterion, which is a measure of violation of the regularity, is proposed. Practical implications. The research results will be used to create a system of fuzzy automatic control by the executive body of the shearer on coal seam hypsometry.