DEVS Simulation of Marginally Stable Systems

In this paper we study the simulation of marginally stable systems using the methods of Quantized State Systems of first order (QSS) and second order (QSS2). We show that the simulation global error can be bounded by a magnitude which grows linearly with the time. Consequently, the direct use of QSS and QSS2 in these systems yields unstable simulation results. Therefore, we propose a modification to the methods which attempts to eliminate the mean value of the perturbations introduced by the quantization in order to avoid the unstability. All this results are illustrated with the simulation of two examples.