Estimation of Observation Error of AUV Using Sonar Positioning System

The paper deals with the problem of estimating the error of the observation of an autonomous uninhabited underwater vehicle, which uses a hydroacoustic positioning system. The purpose of the study is to improve the accuracy of determining the vehicle coordinates relative to reference sonar beacons. It has been established that for the successful operation of the triangulation method in calculating the vehicle coordinates it is necessary that the errors in estimating the distance to all reference beacons have the same sign. To fulfill this condition the idea of selecting the optimal sound velocity value in estimating the distances for each beacon separately has been proposed. An algorithm for calculating the position based on the triangulation method and the subsequent correction of coordinates has been developed. A special feature of the algorithm is the use of several sets of vehicle-beacon distances calculated with different values of the sound velocity in water as input parameters. The selection of the final position estimate is made on the basis of data on the movement of the underwater vehicle relative to the previous known position. The developed algorithm is implemented in the program code and verified by a series of numerical experiments. In the course of the simulation it was found that the proposed solution exceeds the triangulation method in accuracy, reducing the error in determining the vehicle coordinates in half.