Researche On D-S Evidence Theory Based Information Fusion And Its Application In Reliability Data Processing

The development of science and technology lead modern device to large-scale, high-speed, precision and integration. Because the relationship between device and human social development and people life, the reliability of equipment and product gets more and more attention, the requirement to reliability are also getting higher.Reliability engineering is an engineering system through device and produce life cycle. Reliability design, reliability allocation, reliability evaluation, reliability prediction and reliability management are the entire reliability engineering category. With decades of development, people have built a complete reliability theory and method system. Traditional reliability work is based on reliability data, and the theory and method are based on Probability theory.Unfortunately, we face the problem of lack of reliability data with some large scale, high precision, and complex equipment. The reason of lack of reliability data including high reliability leading lack of failure records, high value leading life experiment hard to be carry on, the defect of reliability work leading reliability data accumulation insufficiency.The situation of lack of reliability is called small sample, small sample can not reflect the failure regularity and status on the probability level. If we handle the reliability data with traditional reliability theory and method in the situation of small sample, the analysis result is convincing.In fact, in the whole life cycle of device and product, beside the failure data collected in the experiments and in the using period, there are more data and information which could reflect the device and product’s reliability characters could be got. If we can get these data and information, and make use of these data and information in situation of small sample, we must get more convincing conclusion than the tradition method.This paper proposes to make use of these useful reliability data and information, and get more convincing conclusion based on D-S evidence theory. The main work and contribution of this paper is as follow:(1) Traditional weighted D-S evidence theory combination rule has a unavoidable shortage, when the evidence conflict level is high, and the weight factors of evidence is in a special situation, the fusion result may be contrary to the rational thinking. This paper use cluster effect reduce the influence of“bad”evidence through the analysis to the evidence conflict, reassign weight factor according to the whole conflict level. And compare the fusion result of traditional evidence combination rule and the improved one.(2) Fusion information with D-S evidence theory combination rules, the computation quantity will increase fast when the number of hypothesis and evidence increase, especially in the weighted evidence theory combination rules. This character lead D-S evidence theory combination rule is hard to be implying in engineering practice in some situation. Through vector space analysis, this paper propose a simple information fusion method, which converse the hypothesis in evidence theory into the vertical directions in vector space, and use the vector adding method the handle the information fusion problem.In evidence theory, the distribution information will be ignored in the determination of BPAs with statistics data. To avoid this shortage, this paper proposes a method which brings the distribution information into the fusion process, and evaluates the fusion result’s credibility with the distribution of fusion result. This method also gives the BPAs and distribution information transmission way in multilayer fusion structure.In reliability data analysis practice, we face a situation that the collected data could be grouped in some sets, and there is clear difference among these sets which could not be ignored. This paper proposes a sample character preprocess method, and make use of these sets information in the fusion procedure. And propose the reliability data and information fusion framework on the base of SCPM.In the FMECA analysis to a diesel turbocharger practice, we can not get enough reliability data, and use experts’judgments to risk analysis. With these expert judgments, we use the traditional D-S evidence theory combination rule, simple information fusion method based on vector space analysis and the reliability data and information fusion framework to handle these expert judgments, compare and analysis the results of these three method.