| Nowadays,sonar and underwater equipment are developing rapidly.Faced with different mission requirements,underwater platform presents new features of complex shape and diverse functions.Sonar as an underwater platform "thousands of miles" also ushered in new opportunities for development.At the same time,the scale limitation of underwater sonar platform and the growing demand for detection performance also bring new challenges to passive sonar array design.In this paper,based on the theory of array signal processing and the background of the bow array design of underwater platform such as UUV,the systematic method of arbitrary array design-analysis-optimization is studied for the scale limitation of underwater passive sonar carrier and higher detection performance requirements.Its main work includes the following aspects:The space geometric model of underwater arbitrary array is constructed.Spatial geometry designs of linear array,plane array,volume array and arbitrary array are carried out respectively to maximize the use of platform space.At the same time,the constraints of signal form,array shape and mutual coupling are assumed.Finally,a unified and universal physical model between array element domain signal and spatial excitation is established by coordinate transformation.The influence of array pattern,main lobe width,sidelobe level and array gain on spatial gain performance of arbitrary array is analyzed.Two numerical methods are used:physical-mathematical model based spatial gain numerical analysis method and finite element method based spatial gain analysis method.The former explores the influence of the main lobe width,side lobe level and array gain on the number and frequency of the array elements.The latter realizes the analysis of spatial gain performance of array mounted on baffle.The three-dimensional directivity diagrams of different arrays are given,and the spatial directivity differences of arrays with or without baffles are compared.A parameterized model of complex marine environment is constructed.Based on passive sonar detection mechanism,the detection performance of arbitrary array is analyzed.The influence of target-sonar detection situation and target parameters on the coverage of array detection is explored.It is found that in a certain frequency range,the increase of frequency will reduce the noise of marine environment,increase the directivity index of array,and enhance the detection performance of array,but at the same time,there will be detection burr phenomenon.Aiming at the problems of high side lobe level of uniform array and limited size of matrix platform,array optimization is studied.Intelligent search algorithms such as particle swarm algorithm and genetic algorithm are introduced to optimize the main lobe width and side lobe level.In this way,the array is realized less number of subarray and gotten efficiency and stability.This method is verified by laboratory simulation environment,which provides theoretical support and technical reserve for the design,analysis and optimization of the new sonar system of underwater arbitrary array. |
