Abstract
The multibeam echosounding technique is used to provide seafloor mapping at a relatively high-quality level and requires an accurate positioning and orientation system. Integration of a global positioning system (GPS) and an inertial navigation system (INS) is widely used for positioning and orientation control and is performed by using an inertial unit integrated with a real-time kinematic (RTK) GPS solution with two GPS receivers to provide the required accuracy. However, the RTK-based GPS/INS system is presently limited to a distance of approximately 10 km and cannot be used for offshore hydrographic surveys. Recently, precise-point positioning (PPP) technology has shown promise toward the development of an autonomous GPS solution for positioning applications in which only one GPS receiver is used. This paper investigates a real-time PPP-based GPS/INS integrated system position and orientation solution using the international GPS service (IGS) real-time service (RTS) for hydrographic surveys. To meet this objective, the real-time IGS-RTS PPP-based GPS solution is integrated with the INS solution. It is shown that the real-time IGS-RTS PPP-based GPS/INS integration system fulfills International Hydrographic Organization (IHO) special-order 1a, 1b, and 2 requirements at the 95% confidence level and can be used for onshore and offshore hydrographic surveys.