Abstract: Systems and methods for estimating attitude and heading are provided. The systems and methods utilize carrier phase single difference (CSD) measurements or carrier phase double difference (CDD) measurements and a validation test for CSD or CDD measurement residuals. The systems and methods include applying a wrapping function with limit of ±half of the GNSS carrier signal wavelength to CSD or CDD measurement residuals to generate refined CSD or CDD measurement residuals and validating the refined CSD or CDD measurement residuals variance to determine valid CSD or CDD measurements. By using the validated CSD and CDD measurements, the systems and methods enable low grade hybrid inertial navigation systems to estimate attitude and heading with integrity and without a magnetometer or the need for integer ambiguity resolution even during the static or steady phases of flight/operation.

Abstract: Using geo-mapping data and only at least one inertial sensor, a Bayesian estimator uses at least one element of an uncorrected inertial navigation vector, of a moveable object on a surface, to estimate inertial navigation error information including corresponding statistical information. The estimated inertial navigation error information is used to error correct the uncorrected inertial navigation vector. The Bayesian filter also predicts inertial navigation error information, including corresponding statistical information, for a future time instance when a next uncorrected inertial navigation vector will be obtained.

Abstract: Systems and methods for estimating attitude and heading are provided. The systems and methods utilize carrier phase single difference (CSD) measurements or carrier phase double difference (CDD) measurements and a validation test for CSD or CDD measurement residuals. The systems and methods include applying a wrapping function with limit of ±half of the GNSS carrier signal wavelength to CSD or CDD measurement residuals to generate refined CSD or CDD measurement residuals and validating the refined CSD or CDD measurement residuals variance to determine valid CSD or CDD measurements. By using the validated CSD and CDD measurements, the systems and methods enable low grade hybrid inertial navigation systems to estimate attitude and heading with integrity and without a magnetometer or the need for integer ambiguity resolution even during the static or steady phases of flight/operation.

Abstract: Using geo-mapping data and only at least one inertial sensor, a Bayesian estimator uses at least one element of an uncorrected inertial navigation vector, of a moveable object on a surface, to estimate inertial navigation error information including corresponding statistical information. The estimated inertial navigation error information is used to error correct the uncorrected inertial navigation vector. The Bayesian filter also predicts inertial navigation error information, including corresponding statistical information, for a future time instance when a next uncorrected inertial navigation vector will be obtained.

Abstract: A system and methods for monitoring the integrity of navigation measurement information are disclosed. One method includes receiving a plurality of navigation measurement values, computing a first set and second set of estimates of the navigation measurement values, comparing the first set to the second set, and if the second set is statistically consistent with the first set, computing a plurality of sub-sets of the second set of estimates, computing a sub-solution for each sub-set of the second set of estimates, and computing an integrity value for each sub-solution.

Abstract: An integrity monitoring method for navigation systems with heterogeneous measurements is provided. Measurements from a plurality of different type navigation aiding sources are categorized by an information domain, an aiding class and an aiding section. The information domain is a category of at least one of estimated states and measurements that represent a same physical category. The aiding class is a category that uses a same physical method to acquire measurements. The aiding section is a category of measurements from the same aiding source. The measurements are organized into a plurality of measurement clusters based at least in part on measurement fault modes to be detected, measurement fault modes to be excluded, available computer resources and required performance. An integrity monitoring algorithm is applied to the measurement clusters to determine an integrity solution for all defined integrity monitoring classes.

Abstract: A system and methods for monitoring the integrity of navigation measurement information are disclosed. One method includes receiving a plurality of navigation measurement values, computing a first set and second set of estimates of the navigation measurement values, comparing the first set to the second set, and if the second set is statistically consistent with the first set, computing a plurality of sub-sets of the second set of estimates, computing a sub-solution for each sub-set of the second set of estimates, and computing an integrity value for each sub-solution.

Abstract: A method is provided. The method comprises: initializing a point mass filter; initializing the one or more Bayesian filters; obtaining measurement data associated with a horizontal position on a surface; obtaining measurement data of a horizontal position and a velocity; obtaining geo-mapping data; estimating, with the point mass filter, the horizontal position on the surface based upon the geo-mapping data and the measurement data; estimating, with the one or more Bayesian filters, remaining state parameters based upon an output of the point mass filter and the measurement data; predicting, with the point mass filter, an a priori horizontal position, on a surface for a future time when the next measurement data will be obtained; and predicting, with the one or more Bayesian filters, an a priori remaining state parameters for a future time when the next measurement data will be obtained.

Abstract: A system is provided. The system comprises: a processing system comprising a memory coupled to a processor; wherein the processing system is configured to be coupled to at least one sensor; wherein the memory comprises a grid adaptation system, a system model, measurement data, and an estimation system; wherein the measurement data comprises data measured by the at least one sensor; wherein the estimation system is configured to provide probability density functions (PDFs) for a predictive estimate and a filtered estimate of a state in a form of a point-mass density; and wherein the grid adaption system is configured to adapt grid parameters of a predictive estimate and a filtered estimate.

Abstract: Methods for radar altimeter integrity monitoring are provided.

Abstract: A system is provided. The system comprises: a processing system comprising a memory coupled to a processor; wherein the processing system is configured to be coupled to at least one sensor; wherein the memory comprises a grid adaptation system, a system model, measurement data, and an estimation system; wherein the measurement data comprises data measured by the at least one sensor; wherein the estimation system is configured to provide probability density functions (PDFs) for a predictive estimate and a filtered estimate of a state in a form of a point-mass density; and wherein the grid adaption system is configured to adapt grid parameters of a predictive estimate and a filtered estimate.

Abstract: An integrity monitoring method for navigation systems with heterogeneous measurements is provided. Measurements from a plurality of different type navigation aiding sources are categorized by an information domain, an aiding class and an aiding section. The information domain is a category of at least one of estimated states and measurements that represent a same physical category. The aiding class is a category that uses a same physical method to acquire measurements. The aiding section is a category of measurements from the same aiding source. The measurements are organized into a plurality of measurement clusters based at least in part on measurement fault modes to be detected, measurement fault modes to be excluded, available computer resources and required performance. An integrity monitoring algorithm is applied to the measurement clusters to determine an integrity solution for all defined integrity monitoring classes.

Abstract: A method is provided. The method comprises: initializing at least one non-linear filter configured to provide at least one predictive measurement estimate probability density function; obtaining measurement data; determining if the measurement data is consistent; and if the measurement data is consistent, then estimating at least one state parameter with the at least one non-linear filter using the measurement data.

Abstract: A method of advanced receiver autonomous integrity monitoring of a navigation system is discussed and two modifications facilitating its implementation in a hybrid navigation system are disclosed. In the first approach, relations describing the effect of unmodeled biases in pseudo-measurement on the Kalman filter state estimate are analytically derived and their incorporation into the integrity monitoring algorithm is described. The method comprises receiving a plurality of signals transmitted from space-based satellites, determining a position full-solution and sub-solutions, specifying a pseudorange bias, computing a transformation matrix for the full-solution and all sub-solutions using a Kalman filter, computing a bias effect on an error of filtered state vectors of all sub-solutions, and adding the effect to computed vertical and horizontal protection levels.

Abstract: A method is provided. The method comprises: initializing a point mass filter; initializing the one or more Bayesian filters; obtaining measurement data associated with a horizontal position on a surface; obtaining measurement data of a horizontal position and a velocity; obtaining geo-mapping data; estimating, with the point mass filter, the horizontal position on the surface based upon the geo-mapping data and the measurement data; estimating, with the one or more Bayesian filters, remaining state parameters based upon an output of the point mass filter and the measurement data; predicting, with the point mass filter, an a priori horizontal position, on a surface for a future time when the next measurement data will be obtained; and predicting, with the one or more Bayesian filters, an a priori remaining state parameters for a future time when the next measurement data will be obtained.

Abstract: One embodiment is directed towards a method for determining a heading for a hybrid navigation system with magnetometer aiding. The method includes receiving signals from a plurality of GNSS satellites, obtaining three-dimensional inertial measurements from one or more inertial sensors, and obtaining three-dimensional magnetic measurements from one or more magnetometers. Magnetic bias states are estimated for the three-dimensional magnetic measurements with a magnetic calibration filter using the three-dimensional inertial measurements, data from the signals from the plurality of GNSS satellites, and the three-dimensional magnetic measurements. An artificial heading is calculated based on the magnetic bias states. A main navigation solution can be estimated with a main navigation filter using the three-dimensional inertial measurements, data from the signals from a plurality of GNSS satellites, and the artificial heading.

Abstract: Methods for radar altimeter integrity monitoring are provided.

Abstract: A method comprises receiving a plurality of signals from a plurality of space-based satellites, wherein the plurality of space-based satellites comprises at least one space-based satellite from each of a plurality of Navigation Satellite System (NSS) constellations. The method also comprises determining, in a first domain, a first plurality of sub-solutions based on a respective sub-set of the plurality of signals, each respective sub-set in the first domain chosen according to a characteristic defining the first domain; and determining, in a second domain, a second plurality of sub-solutions based on a respective sub-set of the plurality of signals, each respective sub-set in the second domain chosen according to a characteristic defining the second domain. The method further comprises determining if an error is present in the navigation system based on the first plurality of sub-solutions and on the second plurality of sub-solutions.

Abstract: In one embodiment, a method for selecting a sub-set of satellites from a set of N satellites is provided. The method includes recursively evaluating each sub-set of N?P satellites of a set of N satellites. If only one sub-set satisfies one or more first criterion, then the one sub-set that satisfies the one or more first criterions is selected. If, however, more than one sub-set satisfies the one or more first criterion, then the sub-sets that satisfy the one or more first criterion are evaluated with respect to one or more second criterion and the one sub-set that optimizes the one or more second criterion is selected. Once the selected set of N satellites is equal to the number of satellites from which a receiver is configured to calculate a navigation solution, then that selected set of N satellites is used to calculate a navigation solution.

Abstract: An attitude and heading reference system (AHRS) for a vehicle is provided along with methods for mitigating vehicle acceleration effects in the AHRS. The AHRS comprises an inertial measurement unit configured to generate inertial measurements from at least one accelerometer and at least one gyroscope, a heading source configured to generate heading measurements, and an adaptive statistical filter configured to mitigate the impact of vehicle acceleration effects on attitude and heading.