Why is a lever-arm correction between the GNSS antenna and the INS origin important?

• A. To adjust for battery temperature.
• B. To correct the time stamp.
• C. To convert GNSS measurements to INS reference frame correctly, eliminating systematic errors due to sensor offset.
• D. To adjust the GNSS update rate.

Answer: (C)

The lever-arm correction accounts for the physical distance between the GNSS antenna and the INS origin so that all measurements are expressed in a common reference frame for fusion. The GNSS provides position and velocity at the antenna location, while the INS estimates state at its own origin. Because the platform is moving and rotating, that offset isn’t static: as the vehicle rotates, the offset vector interacts with the angular velocity, adding extra terms to the measured velocity and even to the implied acceleration. By applying the lever-arm correction, you convert the GNSS measurements to the INS origin frame, removing these systematic errors and ensuring the navigation solution remains consistent as the vehicle maneuvers. This alignment is crucial for accurate state estimation in the fusion process, especially during dynamic maneuvers.

Other options don’t fit because adjusting battery temperature, correcting a time stamp, or changing the GNSS update rate doesn’t address the need to transform measurements between two physical locations on the vehicle.