Specification of the State’s Lifetime in the DEVS Formalism by Fuzzy Controller

This work aims to improve simulation performance by introducing fuzzy logic in the discrete event simulation. This paper attempts to develop a new approach to assess the duration of dynamical systems, especially the natural processes. To do, we have used the fuzzy logic theory and particularly the fuzzy inference system combined to the discrete event simulation (DEVS). The process simulation is adjusted by the fuzzy controller which interacts with the input variables of the system. In fact, the fuzzy rules reflect the inputs influence on the duration of processes. The idea is to define a set of fuzzy rules obtained from observers or expert knowledge and to specify a fuzzy model which computes the duration of the process. This duration is then directed towards the simulated model in order to get a new trajectory. In the conventional model, each state is defined by a mean lifetime value whereas our method, calculates for each state the new lifetime according to input variables values. A case study is presented at the end of the paper which is a wildfire spread. It is a challenging task due to its complex behavior, dynamical weather condition, and various variables involved. A global specification of the fuzzy controller and the forest fire model are presented in the DEVS formalism and comparison between conventional and fuzzy method is illustrated.