Method for determining a position deviation, a positioning system and an underwater vehicle

Abstract

A method () for determining a position deviation of a first node the method comprising obtaining () input data, at a first and second position. Said input data comprises, an estimated position of the first node (p) and a first velocity vector (v) of the first node, obtaining () the exact position (p*) of the second node; obtaining () the emitted frequency (f) of an acoustic signal a source; () receiving the acoustic signal (S) and measuring the observed frequency; calculating () a second velocity vector (v) which defines the velocity of the first node in relation to the second node; and calculating (), the angle (α) between the first velocity vector and the second velocity vector; determining () based on the angle, the first velocity vector, and the estimated position of the first node, a line of direction (L) indicating the direction from the estimated position of the first node towards an estimated position of the second node, and determining () based on a first and second line of direction an intersection point defining the estimated position of the second node (p); determining () a deviation vector (V) corresponding to the difference between the estimated position of the second node and the exact position of the second node, and determining () the position deviation of the first node which corresponds to the deviation vector. The disclosure further relates to a positioning system for determining a position deviation for a first node and an underwater vehicle.