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The combination of two or more navigation technologies is called a combined navigation system. According to different requirements, there are various combination navigation systems, with inertial navigation systems being the main subsystems. The integrated navigation system generally has the following 1-3 functions:

① Collaboration function: Utilizing the navigation information of each subsystem to form navigation functions that the subsystem does not possess. The automatic navigator that works with the airspeed information of the atmospheric data computer and the heading information of the compass can provide the position information of the aircraft. It is an early combination navigation system.

② Complementary function: Although the combined navigation function is the same as that of each subsystem, it can comprehensively utilize the characteristics of each subsystem, thereby expanding the scope of use and improving navigation accuracy.

③ Redundancy function: The combination of two or more navigation systems has the function of navigation redundancy, which increases the reliability of the navigation system. The ground velocity signal output by the Doppler radar of the inertial Doppler navigation system has high accuracy, but there is significant transient noise. Inertial navigation systems can provide accurate heading information and have good transient performance of speed signals, but their accuracy is not high. The combination of the two can reduce speed errors, improve the attitude accuracy of the inertial platform, and thus suppress the increase of position errors. The application of Kalman filtering technology can also estimate disturbances such as gyroscope drift (see gyroscope), which improves the performance of inertial navigation systems. Due to the fact that the speed error of inertial navigation is directly related to the attitude error of the inertial platform, this system can also perform aerial alignment of the inertial platform, with an alignment time of about 15-20 minutes. This combination system belongs to autonomous systems and is commonly used in military aircraft.

Inertial Direction Finding, Ranging, and Navigation System

The inertial direction finding and ranging navigation system can directly improve the positioning accuracy of inertial navigation and the attitude accuracy of the inertial platform. It can also perform aerial alignment of the inertial platform, with an alignment time of about half an hour. The azimuth error of the direction finding system is relatively large, so the accuracy of azimuth alignment is also poor. If a dual ranging system is used in combination, it can improve the accuracy of azimuth alignment. Combination can be intermittent or continuous, and this combination system is commonly used in civil aviation aircraft. When flying within the coverage area of the ground response station, it can be used for regional navigation. This system can also perform aerial re alignment of the inertial platform, allowing the aircraft to navigate using aligned pure inertial navigation when flying outside the ground station coverage area.

Inertial Omega Navigation System

Similar in nature to inertial direction finding and ranging navigation systems, it is commonly used for aircraft flying across oceans. The positioning accuracy of the Omega navigation system is lower than that of the direction finding and ranging system, so the airborne alignment time is longer, about 1 hour. In order to shorten the air alignment time and improve the accuracy of the system's velocity information, the inertia Omega Doppler combination is sometimes used.

Inertial astronomical navigation system

Can continuously provide accurate navigation information. Astronomical navigation can measure the angular position of celestial bodies in the inertial platform coordinate system, so when combined, it can not only estimate disturbances such as gyroscope drift, but also estimate the true platform attitude error, thereby distinguishing the zero bias of the horizontal accelerometer. The combination effect of inertial astronomical navigation system is good, but it is affected by climate and cloud cover when used at medium and low altitudes. Doppler radar is often added to this system to form a more complete autonomous navigation system.

Inertial Satellite Navigation System

The Global Positioning System enables aircraft to obtain real-time position and velocity information in any region, with a positioning accuracy of 10 meters. However, during intense maneuvers or when the signal-to-noise ratio of the "navigation star" global positioning system is low, the navigation accuracy will be greatly reduced. Combining the "Navigation Star" global positioning system with the inertial navigation system can not only greatly improve the accuracy of position and velocity information in inertial navigation, but also estimate various interference factors such as gyroscope drift and inertial platform attitude errors, thereby improving the performance of the inertial navigation system. At the same time, utilizing the speed and other information provided by the inertial navigation system can also improve the ability of the "Navigation Star" global positioning system tracking loop to intercept and lock signals. This combination method is the development direction of integrated navigation systems.