Why is time synchronization important in INS/GNSS integration?

• A. Time synchronization aligns timestamps of sensor measurements to ensure proper fusion and consistent state updates.
• B. Time synchronization sets the device's time zone
• C. Time synchronization increases battery life
• D. Time synchronization is not used

Answer: (A)

Time synchronization is about providing a single, shared time reference for all sensors so their data can be fused correctly. In INS/GNSS integration, the inertial navigation system streams high-rate IMU data to propagate the state between GNSS updates, while GNSS gives position and velocity at a lower rate. The estimator (like an EKF/UKF) expects measurements to correspond to the same moment in time. If GNSS data is mis-timestamped relative to the IMU data used for propagation, the correction is applied to a state that doesn’t match the measurement’s actual time, introducing errors and potential instability. Keeping timestamps aligned ensures each measurement affects the state at the correct instant, leading to more accurate position, velocity, and attitude estimates and a consistent, stable fusion.