Mitigation method of acoustic doppler velocity measurement bias

Abstract

A Doppler velocity log (DVL) is used to estimate ship’s velocity by processing seafloor echo. The velocity measurement bias (i.e., long term accuracy) is often regarded as an important technical specification to quantify the accuracy of DVL. The bias describes the accuracy of the instrument after averaging over a sufficiently long time, such that the velocity variance approaches zero. The goal of this paper is to obtain an effective method to mitigate the bias in velocity measurement based on analyzing the DVL seafloor echo characteristics. First, a DVL bottom echo model is constructed based on highlight model, which can focus on the statistical characteristics of the echo waveform information. Then the algorithm for retrieving the echo highlight information is presented. The parameters of the highlight model based on experimental data of DVL echo are analyzed. The intrinsic connection between the highlight model and the point-based scattering model is discussed. Finally, the method of velocity measurement to mitigate the bias according to the relationship between the statistical characteristics of the highlights and bias is put forward. Simulation results show that the proposed method significantly mitigates the bias.