Optimal Star Direction Determination And Precision Analysis Of Celestial-inertial Composite Guidance Scheme

The celestial-inertial composite guidance,which combines the advantages of celestial guidance and inertial navigation,plays an important role in the guidance and control of underwater launched maneuverable ballistic missile.Therefore,this method has been widely actualized in America and Russia.This thesis bases on the single-star scheme with altered platform,and the main contents and innovative points are introduced as follows:Firstly,we obtain the mode of platform adjusting,deduce the model of star-light observation and build equation between error angle of platform and various error source,which based on the analyzing of the single-star scheme with altered platform.In addition, the circle error probability of missile changing with the star azimuth is simulated,whose result shows that the hit precision has been improved efficiently.Secondly,as one solution,we propose a method for quick ascertaining of optimal star,and establish the table of reference azimuth to offer the initial position which supports the searching method with better performance in the whole range.Taking into account that the optimal star may be not available or inexistent in the sky,the ascertaining method of sub-optimal star is put forward,which could provide reference for an optimized choice of navigation star,and consummate the study of quick ascertaining method of optimal star.In the end,the rationality and feasibility of the method are validated by simulation results.Finally,the influence of different inertial error model and fixed azimuth angle of star sensor are considered.The former could be referred to build the inertial error model and set coefficients,while the latter is important for the hit precision of the missile system,which has been proved in the simulation,so we propose optimizing solution based on four dimension simplex method,and furthermore,analyze the regularity of fixed azimuth angle of star sensor in case of simple suppose,that is interrelated results could be used for reference in design of star sensor.In short,all contents of this thesis combine compactly with the ballistic missile project requirements,and large amount of simulations conform the conclusions of the research.It is believed that it could supply theoretical and technological reference for the research and development of interrelated weapon equipment.