Research On Underwater Terrain Matching Navigation Technology Based On Multi-beam System

One of the most important technical challenges of underwater vehicle is the high precision navigation. In recent years, the multi-beam sounding system is widely used in the underwater vehicle, compared with ICCP and TERCOM algorithms which are based on single-beam sounding system, it is helpful to the seabed terrain matching navigation system, including increasing the original terrain information and improving the accuracy and applicability of the matching algorithm. Gray space and feature space navigation models are both set up to study the two-dimensional elevation information matching. Simulations show that the new methods can meet the harsh requirements of underwater terrain matching navigation system. The main contributions of the dissertation are as follows:1 Combined with the general terrain matching navigation system, a new process of terrain matching navigation is given based on the principles of multi-beam sounding system. Grid terrain model is used to describe the multi-beam sounding result, and it is a 2-d density distribution which is like the distribution of image pixels. So the elevation matrix matching can be transformed into gray pixel matching. A gray image matching model is also established to analysis the main error source of it.2 Considering the time and precision, SSDA is a good selection of direct matching methods because of its good performance in fast matching field. A hierarchical search strategy is given based on wavelet analysis. The simulation proves this method is available in seabed terrain matching navigation.3 In order to solve the heading sensitivity of SSDA, Hu moment and Zernike moment are used to describe the feature space of terrain. A series of invariants for Hu moment and Zernike moment have carried on the detailed theoretical derivation and simulation. The circular window search strategy also Guarantee the rotational invariance. Simulation shows that the terrain feature matching has greater ability to resist noise by the moment function.4 Through the dynamic matching, the matching position is confirmed by continuous navigation, so is the error correction. On several typical paths, Comparisons in matching precision, time and applicability are conducted between TERCOM and the method in this paper. All of it tell that the terrain matching based on multi-beam sounding system can be well applied into the terrain matching aided navigation system.