The characteristic brings about some difficulties in the numerical research during their orbital evolution , which leads to the failure of the normalization technique in the general removal impact singularities of celestial mechanics methods and the symplectic algorithm which is successfully applied to the investigation in quality 这一特征给其轨道演化数值研究带来一些困难，包括天体力学方法中一般消除碰撞奇点的正规化处理以及对定性研究十分成功的辛算法都将在不同程度上失效。
The asteroids are the most important small bodies in the solarsystem , and they mainly lies in the two locations - a main belt between the mars ' s orbit and the jupiter ' s and the near - earth space . the most feature of the orbits of near - earth asteroids ( neas ) is that the semi - major axes of the orbits are nearly equal to that of the earth or the perihelia distances are approximate to or even less than the mean distance between the sun and the earth , thus they could move into inside of the earth ' s orbit , so that they might close approach or even colliside with the earth ( or other planets , such as the venus , the mars , etc . ) . the characteristic brings about some difficulties in the numerical research during their orbital evolution , which leads to the failure of the normalization technique in the general removal impact singularities of celestial mechanics methods and the symplectic algorithm which is successfully applied to the investigation in quality . by comparing the computation effects of several common numerical methods ( including symplectic algorithm ) , and considering the nature of the movement of the small bodies , the corresponding treatments are provided here to improve the reliability of the computation 小行星是太阳系最重要的一类小天体，主要分布在两个区域；火星和木星轨道之间的一条主带和近地空间.近地小行星轨道的最大特点是其轨道半长径与地球轨道半长径相近，或近日距离接近甚至小于日地平均距离，其运动可深入到地球轨道的内部，这将导致该类小行星与地球(还有金星、火星等)十分靠近甚至发生碰撞.这一特征给其轨道演化数值研究带来一些困难，包括天体力学方法中一般消除碰撞奇点的正规化处理以及对定性研究十分成功的辛算法都将在不同程度上失效.通过对几种常用数值方法(包括辛算法)计算效果的比较，根据小天体运动自身的特性，给出了相应处理措施，从而可提高计算结果的可靠性
The algorithm of strapdown inertial navigation system is also discussed and then use the flight - track generator to give a simulation , since a closed loop feedback integrated navigation system is designed in this paper , and the output of the filter must feed back to the strapdown inertial navigation system , the analysis of the algorithm in strapdown inertial navigation system is important . the scheme to design the trajectory of gps and the simulation of gps constellation are then studied , the simulation of gps constellation is given from the calculation of vernal equinox base on the principle of celestial mechanics , this method of different from other methods given by other paper and is useful to the research of satellite navigation system . a new method to abstract noise modal in integrated navigation system is proved to be useful in practice , this method , which is given by use the principles of stochastic processes , statistics , time series analysis , and system identification , is suitable for the kalman filter in integrated navigation system 如航迹产生器的设计，该航迹产生器是研究组合导航问题的前提，从国外一些研究组合导航系统的文献中可以看出，设计这样一个航迹产生器是非常必要的，所以本文自行设计了这样一个系统；还讨论了捷联惯性导航系统中捷联解算的方法，并进行了仿真研究，由于在本文设计的闭环反馈式组合导航系统中，对捷联惯导系统的平台误差进行闭环控制，需要将滤波器输出的校正量反馈到捷联解算内部，所以必须对捷联解算进行深入的研究和分析，更何况捷联解算问题本身也是导航界的一个热门研究课题；另外，本文还介绍了gps轨道及其星座仿真的设计思想和方案，与以往gps轨道和星座仿真不同的是本文从天体力学中计算春分点开始，逐步进行gps轨道及其星座仿真，这样的设计方法对从事卫星导航的研究工作是有价值的；还对组合导航中误差建模方法进行了研究，综合运用随机过程、概率统计、时序分析及系统辩识等方面的理论提出了一套适合组合导航卡尔曼滤波的误差建模方法，并运用实际研究工作中的测量数据对该方法进行了验证。
