Creating and testing models of uncertainty systems

Abstract

Technological objects can be subject to various changes in the life cycle process, arising from the peculiarities of technological processes. Such changes include, for example, the formation of scale in the aggregates. As a result, the mathematical description of the object obtained at the previous stages of the life cycle may not correspond to the current state of the automation object. Such systems are called robust. The aim of the work is to define functions for the analysis and description of a high-pressure heater using the MATLAB system, using the Robust Toolbox library. Materials and methods. The initial data of the work was the transfer function of the heater through the flow channel, obtained experimentally. A controller was synthesized for this object and a description of the system and the transient process in MATLAB were presented. The next stage of work was the synthesis of uncertain parameters using the ureal function. As a result, the object received not specific parameter values, but an interval for each of the object's parameters. As a result, an object with uncertain parameters and graphs of its transients was obtained. At the next stage, the nominal parameters of the object were identified and the stability of the system was checked. A system with nominal parameters is stable, so it is possible to perform an analysis of a system with uncertain parameters. To do this, the calculation of robust stability was performed. Robust stability calculation was performed by means of MATLAB, using the robuststab function. As a result of the work, the function allows you to determine a number of values for estimating the system and a combination of system parameters at which the system under consideration becomes unstable. At the next stage of the study, the worst parameters of the system from the selected set were determined; the obtained values differ from the parameters of the robust instability of the system. As a result, the transfer functions of a system with nominal parameters, the worst parameters, and an unstable system are obtained, and the transfer functions are constructed. Results. With the help of the tool for analyzing robust systems, the study of the object was carried out, the ranges of parameters were determined, under which the system will remain stable.