Abstract: A navigation system includes at least one inertial sensor configured to detect motion of the system and generate inertial data; at least one aiding device configured to generate aiding device measurement data; at least one processing unit configured to generate an un-smoothed navigation solution inclusive of navigation state variable error resets based on the inertial data and the aiding device measurement data; wherein the at least one processing unit is further configured to sum the state variable error resets into a cumulative sum of the state variable error resets; wherein the at least one processing unit is further configured to high pass filter the cumulative sum of the state variable error resets; and wherein the at least one processing unit is further configured to subtract the high pass filtered cumulative sum of the state variable error resets from the un-smoothed navigation solution to generate a smoothed navigation solution.

Abstract: One embodiment is directed towards a method of navigating a body. The method includes determining a respective measured direction of each of a plurality of celestial objects with respect to the body based on an output of one or more star tracking sensors mounted to the body. Calculating an expected direction of at least one of the plurality of celestial objects with respect to the body based on a current navigation solution for the body. Calculating an updated navigation solution for the body based on the expected direction of the at least one celestial object, the measured direction of the plurality of celestial objects, and an output of one or more inertial sensors mounted to the body.

Abstract: A navigation system includes at least one inertial sensor configured to detect motion of the system and generate inertial data; at least one aiding device configured to generate aiding device measurement data; at least one processing unit configured to generate an un-smoothed navigation solution inclusive of navigation state variable error resets based on the inertial data and the aiding device measurement data; wherein the at least one processing unit is further configured to sum the state variable error resets into a cumulative sum of the state variable error resets; wherein the at least one processing unit is further configured to high pass filter the cumulative sum of the state variable error resets; and wherein the at least one processing unit is further configured to subtract the high pass filtered cumulative sum of the state variable error resets from the un-smoothed navigation solution to generate a smoothed navigation solution.

Abstract: A navigation system includes at least one inertial sensor configured to detect motion of the system and generate inertial data; at least one aiding device configured to generate aiding device measurement data; at least one processing unit configured to generate an un-smoothed navigation solution inclusive of navigation state variable error resets based on the inertial data and the aiding device measurement data; wherein the at least one processing unit is further configured to sum the state variable error resets into a cumulative sum of the state variable error resets; wherein the at least one processing unit is further configured to high pass filter the cumulative sum of the state variable error resets; and wherein the at least one processing unit is further configured to subtract the high pass filtered cumulative sum of the state variable error resets from the un-smoothed navigation solution to generate a smoothed navigation solution.

Abstract: A navigation system comprises a GNSS receiver that receives GNSS signals on multiple tracking channels, an INS that generates inertial data, and a processor. A micro jump detection and correction module comprises an oscillator micro jump detector that monitors estimates of C/N0 in all tracking channels, and detects a micro-jump event when there is an abrupt decrease of C/N0 in all tracking channels. An offsets module defines a plurality of carrier NCO command offsets to search over signal Dopplers in all available tracking channels after the micro jump event is detected, and sends the carrier NCO command offsets to the GNSS receiver to be added to nominal carrier NCO commands. The micro jump detector selects a tracking channel with the highest C/N0 after carrier NCO command offsets are added to nominal carrier NCO commands, computes corrections for clock error estimates, and sends the corrections for the clock error estimates to a GNSS/inertial Kalman filter.

Abstract: One embodiment is directed towards a method of navigating a body. The method includes determining a respective measured direction of each of a plurality of celestial objects with respect to the body based on an output of one or more star tracking sensors mounted to the body. Calculating an expected direction of at least one of the plurality of celestial objects with respect to the body based on a current navigation solution for the body. Calculating an updated navigation solution for the body based on the expected direction of the at least one celestial object, the measured direction of the plurality of celestial objects, and an output of one or more inertial sensors mounted to the body.

Abstract: A disturbance correction device comprises a disturbance detector configured to detect and output a high frequency component of a measurement signal from an inertial sensor and a level converter coupled to the output of the disturbance detector. The level converter is configured to convert the high frequency component to a direct current (DC) signal. The disturbance correction device also comprises a compensator coupled to an output of the level converter and configured to compare the DC signal with a plurality of thresholds. When the DC signal passes one of the plurality of thresholds, the compensator is further configured to output a respective process noise increment to a Kalman filter. The respective process noise increment corresponds to the passed threshold.

Abstract: A disturbance correction device comprises a disturbance detector configured to detect and output a high frequency component of a measurement signal from an inertial sensor and a level converter coupled to the output of the disturbance detector. The level converter is configured to convert the high frequency component to a direct current (DC) signal. The disturbance correction device also comprises a compensator coupled to an output of the level converter and configured to compare the DC signal with a plurality of thresholds. When the DC signal passes one of the plurality of thresholds, the compensator is further configured to output a respective process noise increment to a Kalman filter. The respective process noise increment corresponds to the passed threshold.

Abstract: A navigation system comprises a GNSS receiver that receives GNSS signals on multiple tracking channels, an INS that generates inertial data, and a processor. A micro jump detection and correction module comprises an oscillator micro jump detector that monitors estimates of C/N0 in all tracking channels, and detects a micro-jump event when there is an abrupt decrease of C/N0 in all tracking channels. An offsets module defines a plurality of carrier NCO command offsets to search over signal Dopplers in all available tracking channels after the micro jump event is detected, and sends the carrier NCO command offsets to the GNSS receiver to be added to nominal carrier NCO commands. The micro jump detector selects a tracking channel with the highest C/N0 after carrier NCO command offsets are added to nominal carrier NCO commands, computes corrections for clock error estimates, and sends the corrections for the clock error estimates to a GNSS/inertial Kalman filter.

Abstract: Systems and methods are provided for compensating nonlinearities in a navigational model. In one embodiment, a system comprises an inertial measurement unit configured to measure inertial motion of a vehicle and an aiding source configured to provide observational measurements of vehicle motion. Further, the system comprises a navigation computer coupled to the inertial measurement unit and the aiding source, wherein the navigation computer is configured to calculate a predicted state and an error covariance data based on the measured inertial motion received from the inertial measurement unit and the observational measurements from the aiding source and calculate variance increments based on attitude uncertainty in the predicted state. Also, the navigation computer is configured to add the variance increments into a process noise covariance matrix for the predicted state and calculate an update for the vehicle motion based on the predicted state, the error covariance data, and the observational measurements.