Research On Integrated Navigation Scheme For Subsonic Vehicles

What this report contributed is the reassembly of current research results instead of creative research results. And it is a feasibility assessment of relative techniques, including the author's subjective opinions.The subsonic vehicle has the characteristics of low speed, longtime flight and low dynamics. Now the main navigation means of such vehicles still adopts inertial navigation, and intermediate navigation adopts terrain contour matching method. The main shortage of inertial navigation is that precision descends along with the lapse of time. And the terrain matching navigation has the shortage of quite longtime task programming and low navigation precision; moreover, the landmarks are extremely rare when the vehicle flies over a desert or sea. Therefore, it is necessary to improve the current navigation means of the subsonic vehicle. The radio navigation will be the preferred means of the integrated navigation of these vehicles.Currently there are two kinds of radio navigation resources in our country. One is the Changhe â…¡ loran, which mainly overlays inshore regions of our country and serves for ships. The advantages of this system include the strong transmitting power, the wide overlaying region, and simple receiving technique. Whereas its precision is relatively low and there exist blind areas in the conjoint region between two chains. The other is Beidou satellite navigation system, which consists of two synchronous satellites working over the equator and the control system on the ground. Its advantage is that the overlaying region is wide. It can overlay our country mainland and the adjacent areas. The shortages of the system include that the target is prone to be exposed for it adopts responsive working mode, and the capacity of users is limited.GNSS includes GPS of USA and GLONASS of Russia. These navigation systems have high precision, and can overlay all over the world. But foreign governments control them. Although America government has cancelled the SA disturbance of GPS now, it is possible for America to resume the disturbance as the change of the international political situation. So the GNSS can only be taken as a reference to our navigation system but not a reliant means.Integrated navigation is a new method. It takes inertial navigation as the principal means, Changhe â…¡ system and Beidou system as the primary measurement means, and GNSS as the reference system, uses distributed federal filter, then alters the weight parameters according to the precision of each navigation subsystem and other situations, and finally carries out the optimal estimation for the flight state of the vehicle.The integrated navigation of the subsonic vehicles needs necessary improvement upon our current radio navigation system. One way is that the receivers of Changhe â…¡ adopt double station chain cooperative system aided with earth conductivity database technology. Another is that the receivers of Beidou satellite navigation system adopt independent time system and thus the responsive work mode can be changed.The report has presented detailed research on concerned instances of integrated navigation and compared it with the system of the subsonic vehicle. The research has shown that the scheme composed of Changhe â…¡ loran, Beidou satellite navigation system and GNSS for such subsonic vehicles is feasible and technically realizable.