FILTERS RESEARCH FOR FREE MOTION EXTRACTION IN SELF-TUNING AUTOMATIC CONTROL SYSTEMS

Abstract

Technological type control objects specific feature, which distinguish them among many mobile or electro technical types, is more low-frequency parametric disturbances spectral composition than spectral composition of coordinate disturbances. Most often parametric disturbances reveal themselves in changing control object transmission coefficient in the channel ―controller control action – control variable‖. On a number of occasions transmission coefficient can change in a wide range – in 2…10 times more than initial value. Coordinate disturbances change control variables but don’t change control object features. Besides spectral density of control variable change, under the impact of coordinate disturbances, has its peak in low-frequency range and characterize forced component of automatic control system motion. Parametric disturbances have influence on control variables and on control object properties, in particular on its transition coefficient. In this case, character of transient processes change, i.e. free motion component of the system. Spectral density of control variable changes, under the influence of transition coefficient change, has its peak, in general, in mid-frequency range. In the case, when using filters, even approximately, it is possible to separate out mid-frequency component from the overall process, which characterizes generally free motion of automatic control system, then it is possible to estimate current value of control object transmission coefficient using parameters change of this component. Such control variable components motions separation is used for designing selftuning ACS. In this case the informative parameter is dispersions difference of control object control variable and control variable of its model in the outputs of linear band pass filters. This dispersion difference is in proportion to current value of transition coefficient. In this article the results of simulation modeling computer experiments of self-tuning automatic control system with opened self-tuning loop are represented. The analysis of filtering efficiency, for three filter model options, are represented as well. The analysis was carried out with three different coordinate disturbances spectral compositions, with the same dynamics of control object and its model and with the different dynamics. Recommendations for filters structures alternatives selection are given. The possibility of optimal parametric tuning of filters is examined.