CREATION OF A MATHEMATICAL MODEL OF A FIVE-INDICATION STATION EXIT SIGNAL IN THE FORM OF A FINITE-STATE AUTOMATON

Abstract

The work is aimed at improving the operational functional reliability of microprocessor-based station interlocking systems by verifying the correctness of system operation during commissioning using simulation models of trackside equipment. Methodology. Various types of mathematical models were analyzed. It was determined that, for the given task, the most effective approach is the use of models based on finite discrete automata, since such a model allows the interaction between the controlled object and the microprocessor-based part of the system to be easily implemented through the selection of input and output parameters. It is proposed to use a Moore finite-state automaton with two output states (signal cleared and signal at stop) and five internal states (signal indication of the railway signal). A finite-state automaton was developed, and its input, output, and internal states were defined. State transition and output tables were constructed, sequential equations describing the automaton operation were derived, and their minimization was performed using an analytical method. The states of memory elements based on three RS flip-flops were determined, and the minimization of their encoding was carried out using Karnaugh maps. A structural diagram of the developed automaton was created, and the model operation was verified using computer simulation. For the first time, a mathematical model of a five-indication station signal with double-yellow aspects and a shunting indication has been developed in the form of a finite-state discrete automaton, which enables its use for simulating the operation of this object under various operating modes. The use of the proposed model makes it possible for the manufacturer to verify the correctness of system operation at the design stage, where the model can be implemented as software emulation without physical realization. It also enables verification of compliance with regulatory documentation during the system commissioning stage at a railway station, where a physical circuit simulating the operation of the signal using logic elements and flip-flops is employed