A GNSS Aided Calibration Method for DVL Error Based on the Optimal-REQUEST

The calibration of scale factor and installation errors plays an essential role to improve the accuracy of integrated navigation system of strap-down inertial navigation system (SINS) and Doppler velocity log (DVL). The DVL measurements will be affected by complex underwater environment, which may affect the calibration results. To solve the above problems, a Global Navigation Satellite System (GNSS) aided separate calibration method for DVL error is proposed in this article. First, an iterative method based on adaptive weight is proposed to calculate the scale factor. Second, a vector observation model is established and the method optimal-REQUEST is introduced to calculate the misalignment angles. In order to improve the estimation accuracy, a vector reconstruction method based on robust filtering is designed according to the measurement variation characteristics of parameter model to reduce the influence of thick tail noise. Finally, the simulation and Yangzi River experiments are conducted to evaluate the feasibility of the proposed DVL calibration method. Experimental results show that the proposed method has a good effect on the calibration of DVL error when DVL measurements are disturbed by noise. Compared to the combined calibration method based on state estimation, iterative method has no need to establish the system noise model, and the estimation result is relatively stable. The river results show that the proposed method is efficient and the positioning result has been greatly improved after calibration.