Specification, safety and reliability analysis using stochastic Petri net models

We focus on the specification and assessment of stochastic Petri net (SPN) models to evaluate the design of an embedded system for reliability and availability. The system provides dynamic driving regulation (DDR) to improve vehicle derivability (anti-skid, -slip and steering assist). A functional SPN abstraction was developed for each of three subsystems that incorporate mechanics, failure modes/effects and model parameters. The models are solved in terms of the subsystem and overall system reliability and availability. Four sets of models were developed. The first three sets include subsystem representations for the TC (traction control), AB (antilock braking) and ESA (electronic steering assistance) systems. The last set combines these systems into one large model. We summarize the general approach and provide sample Petri net graphs and reliability charts that were used to evaluate the design of the DDR in parts and as a whole.