Comparison of MEMS-Based and FOG-Based IMUs to Determine Sensor Pose on an Unmanned Aircraft System

Small-sized unmanned aircraft systems (UAS) are restricted to use only lightweight microelectromechanical systems (MEMS)-based inertial measurement units (IMUs) due to their limited payload capacity. Still, some UAS-based geospatial remote sensing applications, such as airborne spectroscopy or laser scanning, require high accuracy pose (position and orientation) determination of the onboard sensor payload. This study presents ground-based experiments investigating the pose accuracy of two MEMS-based IMUs: the single-antenna MTi-G-700 (Xsens, Enschede, Netherlands) and the dual-antenna/dual-frequency Spatial Dual IMU (Advanced Navigation, Sydney, Australia)/global navigation satellite system (GNSS). A tightly coupled and postprocessed pose solution from a fiberoptic gyroscope (FOG)-based NovAtel synchronized position attitude navigation (SPAN) IMU (NovAtel, Calgary, Canada) served as a reference to evaluate the performance of the two IMUs under investigation. Results revealed a better position solution for the Spatial Dual, and the MTi-G-700 achieved a better roll/pitch accuracy. Most importantly, the heading solution from the dual-antenna configuration of the Spatial Dual was found to be more stable than the heading obtained with the reference SPAN IMU.