Precise position determination of USV based on the IF combination and un-combined PPP ambiguity resolution model

Abstract

Unmanned surface vehicles (USVs) are becoming increasingly important for ocean operations and monitoring, but their precise positioning remains challenging. Real-time kinematic (RTK) technology, commonly used for cm-level positioning in cities, is unsuitable for USVs because it requires nearby reference stations. To address this, we present the uncombined precise point positioning ambiguity resolution (UC PPP-AR) solution, where wide-lane (WL) and narrow-lane (NL) uncalibrated phase bias (UPD) products estimated by the ionosphere-free (IF) PPP model are used. To evaluate the performance of the proposed model, we conducted kinematic USV tests. The results show that the proposed model could shorten the convergence time and achieve cm-level positioning accuracy, with horizontal accuracy better than 2 cm and vertical accuracy better than 5 cm, which is better than that of IF PPP-AR. These results demonstrate the feasibility of the UC PPP-AR technique for USV precise positioning. However, IF PPP-AR may be a better choice if computational consumption time (CCT) is a concern.