Diagnostic Modeling And Analysis Software Design For System Testability

With the continuous improvement of the functions of equipment system,the complexity of the system also increases,leading to the rising difficulty of fault diagnosis and locating and also high testing costs.Therefore,it is an inevitable trend to consider the requirements of system testability in the tache of equipment design and and development.Using computer-aided testability design software to establish the corresponding model of equipment and analyze it can obviously reduce the time for fault detection and location,improve the efficiency of system maintenance,and achieve the purpose of improving reliability of the system and reducing the cost of equipment maintenance.There are mainly two kinds of models applied in system testability modeling abroad: multi-signal flow model and hybrid diagnostic model.The advantage of multi-signal flow model is to distinguish the fault's accessibility to tests in the form of signals,but it cannot reflect the relationship between the faults and the function of the module in the system.The hybrid diagnostic model makes up for the deficiency of the multi-signal flow model well.It combines the faults and functions of the component for analysis,and enriches the types of tests,which can more comprehensively meet the requirements of equipment developers for testability modeling.At present,China has not independently developed the testability analysis software based on the hybrid diagnostic model,and the ability of testability design also lags behind,which is bound to hinder the further development of equipment system.Therefore,it is of great significance to study hybrid diagnostic model and testability analysis theory deeply and apply it to testability modeling and analysis software.This topic comes from equipment pre-research project,cooperates with Beijing Aerospace Measurement and Control Co.,Ltd.,refers to the widely used testability analysis software DSI e Xpress,and study deeply on the system testability modeling and analysis technology based on the hybrid diagnostic model,and develops the software platform,which fills the gap in the field of testability analysis software in China.The main contents of this paper are as follows:First of all,study the principle and steps of hybrid diagnostic model,according to its elements and modeling principle proposed the overall plan of software platform,the required data structure is designed,and the graphical modeling environment is set up,and finally the basic functions,such as drawing graphic,inputing testability information,project management are developed.Secondly,the relevant algorithms for testability analysis of hybrid diagnostic models are studied in detail.Firstly,the traversal algorithm of the model is designed by depth-first search,and the reachability correlation between the faults and the tests is obtained.Furthermore,the algorithm of generating the correlation matrix is designed and the program is completed.Based on the correlation matrix,the algorithm and software scheme of qualitative testability index,such as fault detection rate,fault isolation rate,and quantitative testability index,such as fuzzy group and redundancy tests,are studied with examples.Then,combine the traditional matrix segmentation algorithm by weight function with the Rollout algorithm,the fault diagnosis test sequence is solved and optimized by taking the performance of fault diagnosis and isolation and the cost of tests as the analysis criteria,and it is calculated and analyzed with an example.By designing the fault diagnosis tree generating program,the fault diagnosis sequence is showed on the software interface.Finally,the software performance is tested.The modeling and testability analysis function of the software platform built in this project are verified by combining with a radar system example,and compared with e Xpress,an internationally advanced testability evaluation software.The results show that its performance meets the expected design requirements and can reach the level of the current general commercial testability modeling and analysis software.