Research On Matching Algorithm Of Terrain Aided Navigation System

Terrain matching algorithm is the basis of terrain aided navigation. Terrain aided navigation is very important method of integrated navigation at present, it's also called terrain matching. It makes up of the inertial navigation, wireless altimeter and digital maps virtually. The terrain aided navigation system has remarkable characteristic correcting the error of inertial navigation system and enhancing navigation precision.Firstly, the digital maps are discussed. The two-dimensional statistical model of terrain matching is described by planar non-stationary random process. On the basis of the statistical model of terrain, the simulated digital maps are produced by computer.Algorithm is the core of the terrain matching. This paper introduces briefly several comparatively mature algorithms and its principle, features and application. There are TERCOM,SITAN and similarity measure algorithm.In this paper, the research work focus on the terrain entropy matching algorithm and arithmetic combining terrain entropy and MAD. The algorithm on terrain entropy has its own individual advantage, especially for the complicated zone topography. It can match and analyze a great deal of terrain data rapidly, find the exact position of aircraft, in the case of bigger noises. But terrain entropy algorithm has some disadvantages, such as instability, divergent trend. The MAD algorithm can be quite accurate, the method combining terrain entropy and MAD can eliminate divergent trend effectively.Simulation of algorithm on the terrain entropy is given based on the digital maps resulted from the two- dimensional random process. The results shows that the approach has resistance to errors, it can find matching position swiftly, achieve good matching effect for the area having unique topographical character.