Time Synchronization Error and Calibration in Integrated GPS/INS Systems

The necessity for the precise time synchronization of measurement data from multiple sensors is widely recognized in the field of global positioning system/inertial navigation system (GPS/INS) integration. Having precise time synchronization is critical for achieving high data fusion performance. The limitations and advantages of various time synchronization scenarios and existing solutions are investigated in this paper. A criterion for evaluating synchronization accuracy requirements is derived on the basis of a comparison of the Kalman filter innovation series and the platform dynamics. An innovative time synchronization solution using a counter and two latching registers is proposed. The proposed solution has been implemented with off‐the‐shelf components and tested. The resolution and accuracy analysis shows that the proposed solution can achieve a time synchronization accuracy of 0.1 ms if INS can provide a hard‐wired timing signal. A synchronization accuracy of 2 ms was achieved when the test system was used to synchronize a low‐grade micro‐electromechanical inertial measurement unit (IMU), which has only an RS‐232 data output interface.