What is the primary objective of an integrated navigation system (INS/GNSS) on surface or air platforms?

• A. Improve fuel efficiency through optimization.
• B. Store map data to assist navigation.
• C. Use only GNSS data for position and avoid drift.
• D. Provide continuous, accurate estimates of position, velocity, and attitude by fusing GNSS data with inertial measurements and possibly other sensors, ensuring continuity during sensor outages.

Answer: (D)

The main idea is to combine GNSS data with inertial measurements to produce continuous, accurate estimates of position, velocity, and attitude by blending the strengths of both sensors. The INS gives high-rate, short-term motion information, but its estimates drift over time due to biases and noise. GNSS provides absolute position and velocity in the global frame, but can be interrupted or degraded by signal loss or interference. By fusing these data streams, the system maintains a reliable solution even when GNSS is temporarily unavailable, with GNSS corrections keeping drift in check and the INS sustaining continuity. Other options don’t capture the benefit of combining inertial and GNSS data or the inclusion of attitude and outage continuity.