基于四元稀疏T型阵的AUV方位估计算法

Algorithm of Direction of Arrival Estimation for an AUV Based on Sparse T-Array with Four Hydrophones

小型自主式水下航行器(AUV)受体积和结构限制,携带水听器个数有限,但需具备较高测向精度,而传统四元均匀T型阵虽能实现方位角和俯仰角的联合估计,但由于阵列孔径受波长限制,其定向精度有限。基于此,文中以四元均匀T型阵为基础,增加水平方向上中心阵元与1阵元的间距,使其扩大至波长的整数倍,中心阵元与其他阵元间距均保持半波长,构成四元稀疏T型阵。利用基于常规波束形成的互谱测向法进行方位估计,对2种阵型方位角及俯仰角的估计误差进行仿真对比。仿真结果表明,同一信噪比下,四元稀疏T型阵的方位角估计误差更小,证实了四元稀疏T型阵的定向结果具有更高的精度,可满足AUV以较少的阵元实现更高测向精度的要求。

The number of hydrophone on a small autonomous undersea vehicle(AUV) is extremely limited by its volume and structure, however, higher accuracy of direction of arrival(DOA) is expected for such limited hydrophones. Joint estimation of azimuth and pitch angle can be realized by traditional isometric T-array with four hydrophones, but the estimation accuracy is limited because the array aperture depends on the half-wavelength. This study proposes a sparse T-array with four hydrophones based on the isometric T-array with four hydrophones, and it enlarges the spacing between center element and No.1 element in the horizontal direction to an integer multiple of the wavelength while keeps the spacing between center element and others half- wavelength. Adopting the cross-spectrum direction-finding method based on conventional beam-forming for DOA estimation, the estimation errors of azimuth and pitch angle are simulated and compared between these two array-patterns. The results show that the azimuth estimation error of the sparse T-array is less than that of the isometric T-array under the same signal-to-noise ratio(SNR). Simulation analysis confirms that the DOA result of the sparse T-array with four hydrophones has higher accuracy, which satisfies the requirement for an AUV that using fewer elements to achieve higher DOA estimation accuracy.