Navigator is our multi-satellite navigation filter for onboard, real-time state estimation. Its Extended Kalman Filter is capable of both inertial and relative navigation solutions via a combination of GPS pseudo-ranges and range measurements from inter-spacecraft cross-links. Navigator can run as a stand-alone application or it can be integrated with Autopilot and Guardian for a safe and efficient semi-autonomous navigation and station-keeping solution for multi-satellite missions.
NAVIGATOR is capable of processing GPS measurements with the ability to only use commonly GPS satellites tracked by all modules with the cluster instead of all GPS satellites visible to the module. NAVIGATOR is also capable of using relative range measurements from radio cross-links to provide relative navigation, and support for more measurement types is being developed.
NAVIGATOR can be configured with thresholds to determine the quality of the current navigation solution. If one onboard filter is determined to have poor quality, NAVIGATOR can switch to a different onboard filter automatically. NAVIGATOR can also work with our fault detection, isolation, and recovery management software, GUARDIAN, to provide further robustness. GUARDIAN’s algorithms can monitor additional telemetry from NAVIGATOR to identify faults, and can provide recovery actions.
Validated Extended Kalman Filter
NAVIGATOR consists of an extended Kalman filter (EKF) which has been validated with real GPS data and precise orbit ephemerides from on-orbit missions. NAVIGATOR can also run multiple filters onboard, set up to use different measurement types, use different configurations, and estimate different states (such as absolute or relative states).