Research On Z-based Reliability Modeling And Evaluation Technology Of Embedded System

At present,embedded systems are increasingly used in safety-critical areas such as aerospace and medicine.These systems in safety-critical areas require higher reliability than those in general fields and require higher and higher reliability.How to ensure the reliability of embedded systems has become one of the research hotspots of many researchers at home and abroad.If the reliability can be strictly verified in the early stage of embedded system development,the test and maintenance cost of the embedded system can be greatly reduced.Therefore,it is necessary to study reliability modeling,and evaluation and quantitative analysis in the early development stage to reduce potential software errors and hardware defects in embedded systems.The main research work and achievements of the thesis are as follows:(1)In order to model and evaluate the reliability of embedded software,a combining Z and AADL embedded software reliability model(ZARM)is established.Compared with the existing model,ZARM is a comprehensive model that describes the reliability of embedded software from three dimensions: fault element,static structure and dynamic behavior.In order to quantitatively evaluate the reliability of ZARM model,a DTMC-based embedded software reliability probability model detection method is proposed.The ZARM model is characterized as a DTMC.Combined with the properties of the smooth distribution of MC,the stationary distribution of the state probability of the embedded software is calculated,and the reliability evaluation result is obtained.Finally,the modeling ZARM modeling process is illustrated by an exemplifying embedded software,and the evaluation method is verified.(2)In order to model and evaluate the reliability of embedded hardware,a Z-based embedded hardware reliability model(ZHRM)is established.Compared with the existing model,ZHRM adopts the method of hierarchical modeling.Starting from the composition of embedded hardware,the hardware function module is used as the unit to establish a reliability model for the embedded hardware system.In order to analyze and quantitatively evaluate the reliability of ZHRM,a method based on CTMC for reliability evaluation is proposed.The conversion rules from ZHRM to CTMC are designed.The transfer relationship between states and the transition probability are described in CTMC.The probability of embedded hardware being in each state at a certain moment can be calculated by CTMC,and the key functional module of reliability is identified.Finally,the modeling ZHRM modeling process is illustrated by exemplifying embedded hardware,and the evaluation method is verified.(3)Based on eclipse technology,an embedded system reliability modeling and evaluation framework is established,and the integrated platform of modeling and evaluation is designed and implemented preliminarily.The platform consists of three subsystems,a model transformation subsystem,an embedded software reliability modeling and evaluation subsystem,and an embedded hardware reliability modeling and evaluation subsystem.The test results of the platform function and performance show that the platform can evaluate the reliability of the embedded system with less time consumption,which can greatly shorten the time for reliability verification.