Abstract: A system, apparatus, and method for determining a velocity. A voltage is detected for a planar sensor array while the planar sensor array is moving though a magnetic field, wherein the planar sensor array comprises conductive channels formed in a substrate, wherein the conductive channels are connected in series, and wherein the voltage is generated by the planar sensor array in response to a movement of the planar sensor array through the magnetic field and wherein the voltage is proportional to a velocity of the planar sensor array moving through the magnetic field. The velocity of the planar sensor array is determined using the voltage detected for the conductive channels.

Abstract: A terrain referenced navigation system for a vehicle is disclosed and includes an inertial measurement unit and one or more generic terrain sensors configured to collect terrain-dependent data. The terrain referenced navigation system includes one or more processors in electronic communication with the generic terrain sensors and the inertial measurement unit, and a memory coupled to the processors. The memory stores data into one or more databases and program code that, when executed by the processors, causes the terrain referenced navigation system to determine a predicted terrain value based on a terrain value, where the terrain value is retrieved from one or more sensor specific terrain databases. The pre-Kalman filter processing values are sent to a Kalman filter. The Kalman filter determines navigation corrections and sensor corrections based on the pre-Kalman filter processing values.

Abstract: A terrain referenced navigation system for a vehicle is disclosed and includes an inertial measurement unit and one or more generic terrain sensors configured to collect terrain-dependent data. The terrain referenced navigation system includes one or more processors in electronic communication with the generic terrain sensors and the inertial measurement unit, and a memory coupled to the processors. The memory stores data into one or more databases and program code that, when executed by the processors, causes the terrain referenced navigation system to determine a predicted terrain value based on a terrain value, where the terrain value is retrieved from one or more sensor specific terrain databases. The pre-Kalman filter processing values are sent to a Kalman filter. The Kalman filter determines navigation corrections and sensor corrections based on the pre-Kalman filter processing values.

Abstract: A navigation, take-off, and landing support system (NTLS) that facilitates vertical landing at a landing area by an aerial vehicle comprises a plurality of pseudolites distributed proximate the landing area. Each pseudolite is configured to transmit a radio frequency (RF) signal that facilitates determining, by the aerial vehicle, its position and velocity relative to the pseudolite and whether the pseudolite is operating within a nominal operating range. A monitoring receiver is positioned proximate the landing area and is configured to receive RF signals from the pseudolites. A control system is in communication with the pseudolites and the monitoring receiver. The control system is configured to determine, based on the RF signals received from the monitoring receiver, whether the pseudolites are operating within a nominal operating range and to indicate to each of the pseudolites whether the pseudolite is operating within a nominal operating range.

Abstract: An estimator that is part of a communication network including a plurality of nodes is disclosed. A centralized portion of the estimator includes one or more processors in wireless communication with the plurality of nodes that are part of the communication network, where the communication network includes one or more pairs of collaborating nodes, and a memory coupled to the one or more processors, the memory storing data into a database and program code that, when executed by the one or more processors, causes the centralized portion of the estimator to determine a local update and a collaborative update. The collaborative update is applied to the respective estimated local state vector for both nodes of the pair of collaborating nodes.

Abstract: Systems and methods for inertial navigation aided by signals of opportunity (SOOP). One system includes a network operations center (NOC), a reference station, and mobile user equipment. Another system includes a NOC and user equipment without a reference station. In the latter system, the NOC comprises an antenna, a NOC receiver that generates SOOP data derived from SOOP, a computer system that generates SOOP source location/ephemeris data and inter-source clock bias data based on SOOP data generated by the NOC receiver, and a communication device to broadcast the data. The user equipment comprises an antenna, a navigation receiver that generates SOOP data derived from SOOP detected by the antenna of the user equipment, and a navigation computer system that calculates a navigation solution, including a SOOP-derived estimated position of the user equipment, based on SOOP source location/ephemeris data and inter-source clock bias data broadcasted by the NOC and SOOP data generated by the navigation receiver.

Abstract: Sensor data fusion systems that provide noise reduction and fault protection. The sensor data fusion system fuses data acquired by respective accelerometers having different attributes. For example, one accelerometer has low noise and high bias, while another accelerometer has high noise and low bias when measuring specific force. The high-noise, low-bias accelerometer may be a gravimeter. Gravimeters and traditional accelerometers measure the same physical variable, i.e., specific force. By combining an expensive gravimeter and low-cost accelerometers, a synthetic sensor having both low noise and low bias may be achieved. Such synthetic sensors may be utilized in a gravity anomaly-referenced navigation system to achieve improved navigation performance.

Abstract: A PNT system for a user includes a plurality of sensors configured to collect measurements, where the sensors are grouped into a plurality of subsets of sensors. The PNT system individually compares a measured value collected by each of the plurality of sensors with a corresponding threshold value. The PNT system determines a potential fault condition for a particular sensor exists when the measured value exceeds the corresponding threshold value. In response to detecting the potential fault condition, the PNT system contains the potential fault condition by determining a replacement value. In response to determining a number of times that the potential fault condition is detected exceeds a predetermined value, the PNT system determines a confirmed fault condition with the particular sensor and re-groups the plurality of subsets of sensors. The PNT system proceeds to a second level of fault detection for determining a plurality of individual navigation solutions.

Abstract: A celestial navigation system and method for determining a position of a vehicle. The system includes a star-tracker, a beam director, an inertial measurement unit, and a control module. The star-tracker has a field of view for capturing light. The beam director is configured to change a direction of the light captured in the field of view of the star-tracker. The inertial measurement unit has a plurality of sensors for measuring an acceleration and a rotation rate of the vehicle. The control module executes instructions to correct the attitude, the velocity and the position of the vehicle using the determined magnitude and position of the space objects. The control module also executes instructions to generate corrections to the IMU error parameters, the beam director and star-tracker alignment errors, and RSO ephemeris errors to achieve optimal performance.

Abstract: An estimator that is part of a communication network including a plurality of nodes is disclosed. A centralized portion of the estimator includes one or more processors in wireless communication with the plurality of nodes that are part of the communication network, where the communication network includes one or more pairs of collaborating nodes, and a memory coupled to the one or more processors, the memory storing data into a database and program code that, when executed by the one or more processors, causes the centralized portion of the estimator to determine a local update and a collaborative update. The collaborative update is applied to the respective estimated local state vector for both nodes of the pair of collaborating nodes.

Abstract: A communication network having a plurality of nodes is disclosed. An individual node of the communication network includes a measurement device configured to collect local measurements, an antenna configured to wirelessly connect the individual node to a collaborating node that is part of the communication network, one or more processors in electronic communication with the measurement device and the antenna, a memory coupled to the one or more processors, the memory storing data into a database and program code that, when executed by the one or more processors, causes the individual node to estimate, based on the local measurements, an estimated local state vector for the individual node. The individual node determines a collaborative update based on an estimated collaborative measurement and a collaborative residual, where the collaborative update is applied to the estimated local state vector for the individual node.

Abstract: A celestial navigation system and method for determining a position of a vehicle. The system includes a star-tracker, a beam director, an inertial measurement unit, and a control module. The star-tracker has a field of view for capturing light. The beam director is configured to change a direction of the light captured in the field of view of the star-tracker. The inertial measurement unit has a plurality of sensors for measuring an acceleration and a rotation rate of the vehicle. The control module executes instructions to correct the attitude, the velocity and the position of the vehicle using the determined magnitude and position of the space objects. The control module also executes instructions to generate corrections to the IMU error parameters, the beam director and star-tracker alignment errors, and RSO ephemeris errors to achieve optimal performance.

Abstract: Systems and methods for providing improved navigation performance in which camera images are matched (using correlation) against reference images available from a geolocation-tagged database. An image-based navigation system partitions the camera image (corresponding to the area within the field-of-view of the camera) into a plurality of camera sub-images (corresponding to regions in that area), and then further partitions each camera sub-image into a multiplicity of tiles (corresponding to sub-regions within a region). The partitioning into camera sub-images seeks geometric diversity in the landscape. Each tile is checked for quality assurance, including feature richness, before correlation is attempted. The correlation results are further quality-checked/controlled before the results are used by the Kalman filter to generate corrections for use by the inertial navigation system.

Abstract: Methods and apparatus to monitor GPS/GNSS atomic clocks are disclosed. An example method includes establishing a measured difference between an atomic frequency standard (AFS) and a monitoring device. The method also includes modeling an estimated difference model between the AFS and the monitoring device, and computing a residual signal based on the measured difference and the estimated difference model. In addition, the method includes analyzing, by a first detector, the residual signal at multiple thresholds, each of the thresholds having a corresponding persistency defining the number of times a threshold is exceeded before one or more of a phase jump, a rate jump, or an acceleration error is indicated. Furthermore, the method includes analyzing, by a second detector, a parameter of the estimated difference model at multiple thresholds, each of the thresholds having a corresponding persistency defining the number of times a drift threshold is exceeded before a drift is indicated.

Abstract: A system is provided for structural load assessment of an aircraft. An approximator may receive parameters related to a ground or flight event and calculate the resulting response load on the aircraft using a machine learning algorithm and a structural dynamics model of the aircraft. An analysis engine may compare the calculated response load to a corresponding design load for determining the structural severity of the ground or flight event on the aircraft. A maintenance engine may then automatically perform or trigger a maintenance activity for the aircraft in instances in which the structural severity of the ground or flight event causes a limit exceedance state of the aircraft or at least one structural element thereof.

Abstract: Methods and apparatus to monitor GPS/GNSS atomic clocks are disclosed. An example method includes establishing a measured difference between an atomic frequency standard (AFS) and a monitoring device. The method also includes modeling an estimated difference model between the AFS and the monitoring device, and computing a residual signal based on the measured difference and the estimated difference model. In addition, the method includes analyzing, by a first detector, the residual signal at multiple thresholds, each of the thresholds having a corresponding persistency defining the number of times a threshold is exceeded before one or more of a phase jump, a rate jump, or an acceleration error is indicated. Furthermore, the method includes analyzing, by a second detector, a parameter of the estimated difference model at multiple thresholds, each of the thresholds having a corresponding persistency defining the number of times a drift threshold is exceeded before a drift is indicated.

Abstract: Methods, systems, and computer-readable media are described herein for using a modified Kalman filter to generate attitude error corrections. Attitude measurements are received from primary and secondary attitude sensors of a satellite or other spacecraft. Attitude error correction values for the attitude measurements from the primary attitude sensors are calculated based on the attitude measurements from the secondary attitude sensors using expanded equations derived for a subset of a plurality of block sub-matrices partitioned from the matrices of a Kalman filter, with the remaining of the plurality of block sub-matrices being pre-calculated and programmed into a flight computer of the spacecraft. The propagation of covariance is accomplished via a single step execution of the method irrespective of the secondary attitude sensor measurement period.

Abstract: Methods, systems, and computer-readable media are described herein for using a modified Kalman filter to generate attitude error corrections. Attitude measurements are received from primary and secondary attitude sensors of a satellite or other spacecraft. Attitude error correction values for the attitude measurements from the primary attitude sensors are calculated based on the attitude measurements from the secondary attitude sensors using expanded equations derived for a subset of a plurality of block sub-matrices partitioned from the matrices of a Kalman filter, with the remaining of the plurality of block sub-matrices being pre-calculated and programmed into a flight computer of the spacecraft. The propagation of covariance is accomplished via a single step execution of the method irrespective of the secondary attitude sensor measurement period.