A Bias Compensation Method for Doppler Sonar in Underwater Autonomous Navigation

Doppler sonar estimates the velocity by extracting Doppler information from bottom reverberation, serving as a critical component for high-precision autonomous navigation of underwater vehicles. The configuration of inclined beams results in non-uniform reverberation energy within the illuminated footprint, leading to dynamic velocity bias related to propagation-scattering process. This study establishes a quantitative relationship between the unique transition characteristics of backscattered reverberation in narrow beam and the spatial pattern of reverberation energy. The strictly monotonic relationship with the energy ratios of transitional zones is used to invert the "reverberation energy slope", quantifying dynamic proportional error caused by channel and achieving velocity bias compensation. The experiment demonstrates that after compensation, the temporal oscillation of velocity bias is significantly narrowed, with the range reduced by 29.94% and the variance by 73.50% within 5 hours (over 60 km voyage). The method effectively mitigates the dynamic variation of velocity biases caused by channel differences, enhancing the accuracy of Doppler sonar.