Integration of RTK GPS and IMU for Accurate UAV Positioning - Integrasjon av RTK GPS og IMU for nøyaktig UAV-posisjonering

Abstract

Real-Time Kinematic GPS (RTK GPS) can provide centimeter accuracy and may be used for high accuracy positioning of Unmanned Aerial Vehicles (UAVs).In order to compute its position a Global Navigation Satellite System (GNSS) receiver processes measurements of signals from GNSS satellites. The processing results in a delay before the position measurement is available to the UAV. If the UAV is highly dynamic the delayed measurement will describe a past position, resulting in reduced accuracy.

This thesis presents the hardware and software architecture of an integrated Real-Time Kinematic GPS/Inertial Navigation System (RTK GPS/INS) for UAV applications that compensates for the time-delay. The RTK GPS system is constructed using single-frequency GPS receivers and the open-source Real-Time Kinematic Library (RTKLIB). The RTK GPS/INS navigation system is implemented in the DUNE(DUNE:Unied Navigation Environment)-framework running on the embedded payload computer of the UAV. The integration of RTK GPS and ineartial measurements is performed by a nonlinear observer estimating the delayed states and recovering the current states using inertial measurements. Hardware-in-the-Loop simulations and experimental ights with the x8 Skywalker UAV are used to test the navigation system.