Simulating real virtual ocean environment is necessary for the research of interaction simulation of underwater gravity aided inertial navigation system. One of the key techniques of realizing virtual ocean environment is modeling and simulating three-dimensional ocean waves. Numerical simulation of three-dimensional ocean waves in the case of different wind speeds is realized using MATLAB based on directional spectrum composed of Pierson-Moscowitz frequency spectrum and directional spreading function. Experiments show that the simulation speed is fast and the simulation results are vivid if suitable simulation frequency band, interval of wave frequency and interval of direction angle are selected. The simulation can provide some technological supports for interaction simulation of gravity aided navigation system for underwater vehicles.
Considering the requirements of the high accuracy, high reliability and real-time capability for the aircraft geomagnetic correlation matching algorithm, the similarity core function, geomagnetic properties and search methods will be processed synthetically in this paper. The correlation variance is introduced as the similarity core function, the feature normalization of the geomagnetic field is introduced as the matching parameters and the differential evolution algorithm is introduced for reducing the running time. The experiments have been done in the laboratory based on the actual measured geomagnetic field data, its results show that: the matching probability and accuracy of the new algorithm are better than the traditional one on the whole and the average running time is shortened from 7~11s to 1~2s.
The outlier identification and correction of the geomagnetic parameter measurement is an important influencing factor for the probability and precision of the matching algorithms. The ream-time measurements of the geomagnetic field parameter can be considered as the first-order non-stationary random process, the real-time measurement value can be predicted by using the multi-level recursive method, the outlier identification can be done by the Dixon criterion, and the correction can be made by using the median filter and the one step prediction value. The inspection is carried out by using the emulation data and actual data, the results show that not only the isolated type but also the spot-type outlier value can be detected well and the signal reconstruction error is less than 5%.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.