I. Introduction
With the development of the modern marine technology, the navigation technology attracts more and more attentions. And the navigation accuracy determines the effect of the task to complete directly. Although the inertial navigation is a completely autonomous navigation method, it has a fatal drawback that the navigation positioning error grows over time, caused by its inertial components [1]. So the Inertial Navigation System (INS) is difficult to work long time independently. Generally speaking, there are two ways to solve this problem: the first one is to improve the precision of the inertial sensors and the other one is using the integrated navigation technology. Since the first one needs to improve the production technology of the inertial sensor significantly and will pay a high price, the second way is much more popular in modern navigation fields. The integrated navigation system can improve the navigation precision availably only using properly integrated navigation algorithm and remaining the inertial sensors unchanged [2]. On the basis of the inertial navigation device with medium accuracy and integrated with auxiliary attitude and position sensors or systems, such as the Global Position System (GPS), the Doppler Velocity Log (DVL) and so on, the INS can provide effective corrected information which is high-precision. So an integrated navigation system whose long-term stability and precision of the system are both the best is formed eventually. Various integrated navigation systems such as INS/GPS, Micro Electro Mechanical System (MEMS)/GPS and the combination of Gyro/Magnetometer system have been widely used [3]. With the emergence of integrated navigation technology, high precision navigation effect is possible though making use of the general medium accuracy of inertial navigation instrument.