NAAC Algorithm And Its Application For Intelligent Fault Diagnosis System

Driven by some emerging applications, digital system integration is on the rise. To serve digital system fault detection requirements, a lot of intelligent fault detection and diagnostic methods have been found. However, in most of fault diagnosis system, it is a difficult thing to classify multi-line short circuit fault from fixed logic fault. To solve the puzzle, the paper author widely study in Boolean Matrix theories , fault detection and condensing theorem, fault diagnostic soundness theorem and anti-aliasing theorem. In addition, the author also research in general detection optimal algorithm used by fault diagnosis system, these detection optimal algorithm can classify into two types, the first type is that algorithm must be able to find the PTVs (Parallel Test Vector)which has the best condensing index P under fault location precision request, these algorithm include WOA optimal algorithm, True/Compliment optimal algorithm; The second type is that algorithm must be able to find the PTVs which has the best fault location precision under the condensin index P request. These algorithms include minimum weight value optimal algorithm. But these general detection optimal algorithms have a lot of flaw in test time cost or low fault coverage rate. Therefore, the paper brings up a new detection optimal algorithm that belongs to the first type: NAAC (No Aliasing and Anti-Confounding) detection optimal algorithm, and put the NAAC detection optimal algorithm into a practical intelligent fault diagnosis system. The NAAC detection optimal algorithm can assure to generate test matrix with no symptom aliasing and no symptom confounding, at the same time, it can compress a large of scale test matrix to verysmall of scale test matrix. The PTV of test matrix is different for each other, but has same weight value. And the weight value can be appointed by fault diagnosis system designer. When those PTVs are sequentially loaded to CUT (Circuit Under Test) from intelligent fault diagnosis system, homologous PRVs (Parallel Response Vector) are taken back. Through test response analysis by expert system , Intelligent fault diagnosis system can detect all fixed'1'logic fault, fixed'0'logic fault, and detect the majority of multi-line short circuit fault. Practical analysis and experimental results show that the NAAC detection optimal algorithm is characterized by almost full error coverage.The paper also discusses two intelligent fault diagnostic methods: expert system intelligent fault diagnostic method and boundary-scan technique intelligent fault diagnostic method. Benefit from designer experience, Expert system regulations are built by C language. Through the inference, all fixed logic fault and most multi-line short circuit fault are detected by expert system. On that account, the design process built by C language will be a mode that can be imitated by other intelligent fault diagnosis system. On the other hand, Boundary-scan technique intelligent fault diagnostic method was applied to practice. For most digital system, devices with boundary-scan architecture are broadly used. Only using four line or five line to connect PC parallel port with CUT TAP (Test Access Port), all the PTVs can be loaded to CUT and all homologous PRVs can be taken back to intelligent fault diagnosis system. The method extremely simplifies diagnosis system design. .In this intelligent fault diagnosis system, virtual instrument technology is a key point. "Software is instrument" isn't a slogan but a fact. The author designs diagnosis system software with Delphi 6.0 , the whole system are divided according to functional block. Some of the blocks are written by MCS-51 ASM language and VHDL hardware description language. With the powerful GUI (Graph User Interface), this diagnosis system is ease to use, and can be conveniently transplanted into other applications.In the hardware part of the intelligent fault diagnosis system, a circuit board for interface is design meticulously by author, the interface board connects PC with CUT, all l...