Pose Estimation of UAVs Based on INS Aided by Two Independent Low-Cost GNSS Receivers

Abstract

Increasing use of UAVs in high-precision applications, such as georeferencing and photogrammetry, increases the requirements on the accuracy of the estimated position, velocity and attitude of the vehicle. Commercial systems that utilize magnetometers in the heading estimates are cheap, but are affected by disturbances from both the vehicle itself, nearby metal structures and variations in the Earth's magnetic field. On the other side, commercial dual-antenna satellite navigation systems can provide the required accuracy, but are expensive. This paper explores the use of a low-cost setup using two independent GNSS receivers, aiding an inertial navigation system by using pseudorange, Doppler frequency and carrier phase measurements from two longitudinally separated receivers on a fixed-wing UAV. The sensor integration was based on a multiplicative extended Kalman filter (MEKF). The main contribution of this paper is the derivation of measurement models for the raw GNSS measurements based on the MEKF error state, taking into account antenna lever arms and explicitly including the difference in measurement time between the receivers in the measurement model for double differenced carrier phase. The proposed method is verified using data collected from a UAV flight.

Real-time georeferencing of thermal images using small fixed-wing UAVs in maritime environments

“…The translational motion observer is based on measurements from an accelerometer and RTK-GNSS receivers. The attitude observer utilizes angular rate measurements and reference vectors that are extracted from an accelerometer, and pitch and yaw measurements from two RTK-GNSS receivers with separate antennas (Sollie et al, 2019).…”

Control System Architecture for Automatic Recovery of Fixed-Wing Unmanned Aerial Vehicles in a Moving Arrest System

“…Another solution is to equip the arrest system with multiple position sensors to find the orientation of the baseline between them, see e.g. [38] or [39] that reports 0.27 • precision for a baseline of about 0.5,m using GNSS. Depending on the dynamics of the arrest system and the precision requirements, a combination with inertial sensors may be required to provide smoother estimates at a higher rate.…”