When there is a GNSS outage and the signal from GNSS satellites is lost or compromised, the GNSS-based Inertial Navigation System (INS/GNSS) must rely on its inertial sensors to continue determining its position. The following parameters and conditions can affect the size of position drift in this case:
– Calibration accuracy of sensors
– Sensor aging
– GNSS signal quality before the outage
– Vibrations
– Temperature changes
– Pressure changes
– Integration errors
– Length of GNSS outage
– Use of algorithms to compensate for drift effects
– Availability of reference data or alternative navigation systems (e.g. external velocity)
Including sensor aging and the last calibration date, which can significantly affect the system’s drift, the numerous factors make it challenging to accurately predict the drift behavior in seemingly uniform conditions. As a result, even when testing under similar conditions, using different Inertial Navigation Systems can result in substantial variations in position drifts. Furthermore, the quality of the GNSS signal just prior to the outage also has a major impact on the system’s drift behavior.
