Impact Source Location Method For Manned Sealed Capsule Based On Acoustic Emission

Natural phenomenon such as star collision and human space activities could create space debris. The space debris surrounds the earth threatens security of spacecraft in orbit. With the development of space technology, requirements of spaceflight increase in our country which implies the necessity of ensuring the security of manned spacecraft and astronauts’ lives. When space debris impacts a manned sealed capsule, the bulkhead may be penetrated or damaged which will result in the leakage of inside gas and dangerous incident may occur. One function of in-orbit monitoring system is to provide the impact source location of manned capsule to ensure the security of astronauts and help repairing the spacecraft.Among the various localization techniques, acoustic emission technique with its advantages such as passive perception, low cost, and applicable to large measurable objects implies that it is suitable to be used to localize impact source. Further, the rule of K-nearest neighbour method is simple, easy to use and applicable to space technology. Based on K-nearest neighbour method, accuracy could be improved through combining cluster analysis and fuzzy theory. The main content of the article is as follows:(1) Choose the article’s research method based on the theory of regional localization. Achieving high accuracy localizing result through experiments on localizing impact source of manned spacecraft, generate new signal by adding disturbance to the existing signal, and apply the localization method to manned sealed capsule.(2) Improve the localizing accuracy based on regional localization, narrow down the scope of researching objects to small region and do regional impact source localizing experiments to get the training and testing data of each small area. Apply Knearest neighbour method to achieve localizing result and compare to reach the conclusion. Meanwhile, do deviation analogic experiments against the problem of existence of noise in signals. Analyse the result and prove the irrelevance of geometrical distance and vector distance in this research.(3) Based on K-nearest neighbour algorithm, combine cluster analysis to derive kmeans cluster algorithm and combine fuzzy theory on basis of that to get fuzzy c-means cluster algorithm. Use three algorithms to localize impact source and analyse the influence of difference parameters to K-nearest neighbour algorithm. Analyse the influence of location of test point and signal fluctuation to the localizing result. Analyse the effect of applying K-means cluster algorithm and fuzzy c-means cluster algorithm. Analyse the advantages and disadvantages of the three algorithms in practical use.