Parameterized GSPN Model and Extended Dependability Block Diagram for Reliability Evaluation of Embedded Systems

In this study we focus on the specification and evaluation of parameterized generalized and stochastic Petri net (GSPN) models for reliability and safety estimates of embedded systems. The embedded system to be modeled is specified using the extended dependability block diagram (EDBD), a high-level system specification model, which is composed of several and diverse blocks: functional, decision, standby spare, multiple and subsystem. For each block, parameterized GSPN model parameters may be defined as: failure and repair rates, failure and success probabilities, redundancy and number of redundant components (if any), mean time to failure (MTTF) and mean time to repair (MTTR) among others. The parameterized solution helps the development of high-level automation tools. The parameterized GSPN models are concise and changeable models, based on few block models (with small variations). These models, depending on the parameters, can assume different structural configuration. Through Markovian and non-Markovian distributions functions, evaluation of series, parallel, m-out-of-n and other complex structures are possible. Non-Markovian distributions can be represented by composition of exponential distributions by means of method-of-stages through moment matching technique or by analytical expressions into a random switch, a GSPN construct. At the end, a case study related to a flight-control system solution is presented and estimates are shown which validate the proposed model.