| Reliability,testability,maintainability and safety(RTMS)are the core quality properties of complex industrial products for safe and efficient use.In the aviation field,aircraft functional system with highly complex technology and its special security requirement especially need high targets in the comprehensive performance of RTMS.In the process of research and development of domestic modern military and civilian aircraft,there are still some mismatches and contradictions between system function design and evaluation with a detailed quantized RTMS measures system,which restricts the development of model projects to a higher quality technology level.The design philosophy of the integration of RTMS emphasizes the organic combination of RTMS modelling,evaluation and system function design and stresses the efficient information feedback between them,which needs to study the techniques for modelling system RTMS synthetically,the techniques for characterizing the logic uncertainty and dynamic nature of complex systems intensively and the techniques for computing system RTMS measures in a detailed way.As a general system modelling tool,Petri net has good ability of descripting the dynamic behavior of a complex system and quite suitable for constructing a model that integrates system RTMS information synthetically.This dissertation is intended to deveplop a Petri net model that could integrate RTMS information of aircraft system and study a detailed quantification analysis method for computing RTMS measures in the Petri net model,to raise the technical level of synthesizing RTMS information of a complex engineering system,as well as the engineering application abilitie.The main research work of the dissertation is outlined as follows: 1)The basic definitions and key measures of RTMS are summarized.The Bayesian network and Markov chian method in the application of system probability accurate calculation is analysized,which provides theoretical basis for validating the correctneness of the proposed RTMS model with its detailed quantification analysis method.2)By dividing failure into two new modes—physical failure and non-physical failure,a new state "function abnormal" is raised as a supplement to the traditional normal state and failure state.By the state "function abnormal",a method for converting system function principle diagram to a three-state model is developed and is called "three-state modelling method" for short.On the basis of three-state modelling method and by adding system RTMS information into the three-state model above,a framework for building RTMS model according to system function principle diagram is proposed.3)The characteristics of fault propagation in an aircraft system are studied from the aspects of longitudinal dependency,the complexity of fault mode,time-sequence,logic complexity and so on.With a summary of Petri net in graphic expression,a Petri net named Dynamic Colored Stochastic Petri Net is put forward.Furthmore,with the guide of the framework for building RTMS model,Dynamic Colored Stochastic Petri Net with RTMS integrated is constructed by combining aircraft system RTMS information.The propsed Dynamic Colored Stochastic Petri Net with RTMS integrated is capale of characterizing the state diversity,logic uncertainty and dynamics of a system,and hence it can describe the evolution process of a system more realistic and intuitive than traditional modes.4)With the increasing of system scale,there will be a state combination explosion problem by using exact method for system analysis.Therefore,on the basis of Monte Carlo simulation principles and by combining firing rules,a simulation method called "fault propagation simulation algorithm" with its two extended algorithms "fault propagation simulaition algorithm 2" and "reachability analysis algorithm" is exploxed for the proposed Dynamic Colored Stochastic Petri Net with RTMS integrated.With the samples achived from those three algorithms,a statistical method for computing RTMS measures is presented in depth.The three simulation algorithms and the corresponding statistical method form a systematic way for analysizing the reliability,testability,maintainability and safety of a system.5)The propsed modelling and simulation method is applied to two l ongitudinal fly-by-wire flight control systems,a simple one and a complex one separately.In particular,the simple one is used to demonstrate the correctness of the propsed method in comparision with the results achived by traditional accurate method.The complex one is analysized to illustrate the practicability of the proposed method when it applied to large complex engineering system.In addition,a scheme for storaging the model of Dynamic Colored Stochastic Petri Net with RTMS integrated and its basic RTMS information is raised.Furthermore,the logic for realizing the proposed algorithms for system RTMS anaylsis in compute is studied.Eventually,software called RTMS_Petri is designed,realized and verified.6)In view of the important technical value of importance degree for system reliability,testability,maintainability and safety evaluation in engineering,simulation method for computing structure importance degree,probability importance degree and critical importance degree is studied on the basis of "fault propagation simulation method",which is a complement to RTMS analysis for a static two-state system.Several instances are presented and analysized to validate the new proposed modelling and simulation method.The results show that proposed modelling method can intergrate basic RTMS information effectively and has the ability to bulid a Dynamic Colored Stochastic Petri Net with RTMS integrated,which refects the operation of a system in more detailed and realistic way.In addition,the results demonstrate that the suggested simulaition method can used to computer RTMS measures correctively,which supports the RTMS evaluation work done during the system function design and can promote the development of technology in coordinationg and synchronizing RTMS and function design for complex engineering system... |
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