Compass Alignment Error Compensation Method for Underwater Vehicles in Inshore Environments

It is using Doppler velocity to assist the compass alignment that solves the speed error problem in the compass alignment. The vehicle acceleration also leads to the compass alignment error. When the underwater vehicle works in the nearshore environment, it is seriously disturbed by the rapid change of current line acceleration, which will produce greater compass alignment error. In order to further improve the compass alignment accuracy, the influence and compensation of the underwater vehicle linear acceleration on compass alignment has become an urgent issue for inshore underwater compass alignment. Based on this background, the compensation method of the compass alignment of the inshore underwater vehicle is proposed. Firstly, the influence mechanism of linear acceleration on compass heading error is studied, and the compensation method of compass linear acceleration error based on Doppler velocity difference is analyzed. Finally, the error data reflecting the error characteristics of the doppler velocity log is extracted from the actual measurement data of the doppler velocity log, superimposed on the velocity truth value to generate semi-physical data, and the proposed method is verified by semi-physical simulation. The experimental results show that the maximum value of heading angle oscillation is reduced by about 96% after adopting the method proposed in this paper, and the time to converge to steady state again decreases from 300-400s to 200-250s. The data processing results show that the linear acceleration obtained by the DVL velocity difference compensates for the linear motion acceleration in the compass control loop, reduces the violent oscillation of the compass alignment result, and improves the heading alignment accuracy of the nearshore underwater robot.