Information Fusion Method Based On Desert-smarandache Theory For Fault Diagnosis

Dempster-Shafer Theory (DST) in information fusion has been widely applied in the fault diagnosis, since its advantage in the representing, measurement and combination of uncertainty. However, the existing DST-based fault diagnosis method is mainly used to deal with single fault diagnosis problem, since simultaneous faults can not be characterized in DST because of the fundamental assumption of"mutually exclusive". A new theory of plausible and paradoxical reasoning, known as Dezert-Smarandache Theory (DSmT) relaxes the exclusivity constraint in DST and provides an unified frame of discernment for both single fault and simultaneous faults diagnosis, representing, measurement and fusion of uncertainty. On the other hand, both DSmT and DST have some strict limitation that can not be satisfied in practical application, such as the dependent evidence, incomplete frame, dynamic frame and so on. This thesis provides many new methods for evidence combination that focus on these problems. The main contributions are as follows:(1) Some problems in DST that deals with dependent evidence, incomplete frame and dynamic frame are analyzed, a comprehensive overview of the latest development of the theory are summarized.(2) The combination method for dependent evidence and its application for simultaneous faults diagnosis are presented. According to the characteristics of simultaneous faults, a frame of discernment is given for both single fault and simultaneous faults diagnosis, and the DSmT combination rule applicable to simultaneous faults diagnosis is introduced; then, the dependence of evidence is classified according to the difference of three factors: sensors, types of fault features, methods for extracting of fault feature, and a new method for evidence decorrelation is provided; next, DSmT combination rule is used to aggregate the decorrelated evidence.(3) A new DSmT combination rule in open frame of discernment and its application for simultaneous faults diagnosis are established. This method can deal with the conflict resulting from the incomplete frame. A two-dimensional measure factor in DST is extended to DSmT to judge the degree of conflict between evidence, and the combination rule is selected according to the degree.(4) A research on conditional DSmT combination rule and its application for simultaneous faults diagnosis are carried out. The limitation of DSmT for handling the dynamic frame of discernment is introduced; then, the Dempster's rule of condition and similar Dempster's rule of condition in DST are given to update the evidence; next, the conditional rule in DST is extended to DSmT to deal with the diagnosis of simultaneous faults.For the (2)⁴ problems, some examples in fault diagnosis of motor rotor are given to illustrate the effectiveness of the proposed combination rule.