Abstract: Embodiments of the present invention provide improved systems and methods for estimating N-dimensional parameters while sensing fewer than N dimensions. In one embodiment a navigational system comprises a processor and an inertial measurement unit (IMU) that provides an output to the processor, the processor providing a navigation solution based on the output of the IMU, wherein the navigation solution includes a calculation of an n-dimensional parameter. Further, the navigational system includes at most two sensors that provide an output to the processor, wherein the processor computes an estimate of an n-dimensional parameter from the output of the at most two sensors for bounding errors in the n-dimensional parameter as calculated by the processor when the trajectory measured by the IMU satisfies movement requirements, wherein “n” is greater than the number of the at most two sensors.

Abstract: Systems and methods for navigation using cross correlation on evidence grids are provided. In one embodiment, a system for using cross-correlated evidence grids to acquire navigation information comprises: a navigation processor coupled to an inertial measurement unit, the navigation processor configured to generate a navigation solution; a sensor configured to scan an environment; an evidence grid creator coupled to the sensor and the navigation processor, wherein the evidence grid creator is configured to generate a current evidence grid based on data received from the sensor and the navigation solution; a correlator configured to correlate the current evidence grid against a historical evidence grid stored in a memory to produce displacement information; and where the navigation processor receives correction data derived from correlation of evidence grids and adjusts the navigation solution based on the correction data.

Abstract: A navigation device is provided herein comprising an inertial measurement unit (IMU), a camera, and a processor. The IMU provides an inertial measurement to the processor and the camera provides at least one image frame to the processor. The processor is configured to determine navigation data based on the inertial measurement and the at least one image frame, wherein at least one feature is extracted from the at least one image frame based on the navigation data.

Abstract: A method of stabilizing heading in an inertial navigation system includes operating an inertial measurement unit comprising horizontal-sensing elements and off-horizontal-sensing elements while the inertial measurement unit is in a first orientation, calibrating the horizontal-sensing elements of the inertial measurement unit based on horizontal aiding measurements, forward-rotating the inertial measurement unit by a selected-rotation angle about a horizontal-rotation axis so that the inertial measurement unit is oriented in a second orientation, operating the forward-rotated inertial measurement unit while the inertial measurement unit is in the second orientation, and calibrating the rotated off-horizontal-sensing elements based on horizontal aiding measurements while the inertial measurement unit is in the second orientation. When the inertial measurement unit is in the first orientation, the horizontal-sensing elements are oriented in a horizontal reference plane.

Abstract: A method for navigating underwater is disclosed. The method uses a navigation system to project a first velocity measurement along one or more signal beams having a second velocity measurement, where the second velocity measurement is related to at least one of the one or more signal beams. The method determines a position and location of an object associated with the navigation system based on a prediction of at least the second velocity measurement, and the navigation system is adjusted to perform within a prescribed measurement range based on a covariance of the first and second velocity measurements. The performance adjustments made in determining the position and location of the object are operable independent of the navigation system maintaining each of the signal beams due to one or more external environmental conditions.

Abstract: A method for navigating underwater is disclosed. The method uses a navigation system to project a first velocity measurement along one or more signal beams having a second velocity measurement, where the second velocity measurement is related to at least one of the one or more signal beams. The method determines a position and location of an object associated with the navigation system based on a prediction of at least the second velocity measurement, and the navigation system is adjusted to perform within a prescribed measurement range based on a covariance of the first and second velocity measurements. The performance adjustments made in determining the position and location of the object are operable independent of the navigation system maintaining each of the signal beams due to one or more external environmental conditions.

Abstract: Systems and methods for terrain contour matching navigation are provided. In one embodiment, a method for terrain contour matching navigation comprises: receiving at least one sample point representing the position of an aircraft, the at least one sample point including a horizontal position and an altitude sample; correlating a first sample point of the at least one sample point across a reference basket array having a plurality of elements; determining a correlation quality; when the correlation quality does not achieve a pre-determined quality threshold, performing at least one additional correlation of an additional sample point of the at least one sample point across the reference basket array; and when the correlation quality does achieve a pre-determined quality threshold, calculating a position error based on the correlating of the first sample point and any additional correlations of any additional sample points.

Abstract: A method of stabilizing heading in an inertial navigation system is provided. The method includes operating an inertial measurement unit comprising horizontal-sensing elements and off-horizontal-sensing elements while the inertial measurement unit is in a first orientation, calibrating the horizontal-sensing elements of the inertial measurement unit based on horizontal aiding measurements, forward-rotating the inertial measurement unit by a selected-rotation angle about a horizontal-rotation axis so that the inertial measurement unit is oriented in a second orientation, operating the forward-rotated inertial measurement unit while the inertial measurement unit is in the second orientation, and calibrating the rotated off-horizontal-sensing elements based on horizontal aiding measurements while the inertial measurement unit is in the second orientation. When the inertial measurement unit is in the first orientation, the horizontal-sensing elements are oriented in a horizontal reference plane.

Abstract: Systems and methods for reducing vibration-induced bias errors in inertial sensors are disclosed. A system for reducing bias errors in an inertial sensor operating within an environment may include a vibration detector for sensing vibration changes within the environment proximate to the inertial sensor, and a Kalman filter for computing an estimate of the navigational error produced by the inertial sensor due to a vibration-induced bias shift detected by the vibration detector. The vibration detector can be configured to measure an accelerometer output of the inertial sensor over a Kalman filter cycle, and then use the standard deviation of such output to obtain a statistical measure of the vibration within the environment. In some embodiments, the inertial sensor may include an inertial measurement unit (IMU) connected to an error compensation unit and strapdown navigator, each of which can be fed navigation corrections determined by the Kalman filter.

Abstract: Systems and methods for terrain contour matching navigation are provided. In one embodiment, a method for terrain contour matching navigation comprises: receiving at least one sample point representing the position of an aircraft, the at least one sample point including a horizontal position and an altitude sample; correlating a first sample point of the at least one sample point across a reference basket array having a plurality of elements; determining a correlation quality; when the correlation quality does not achieve a pre-determined quality threshold, performing at least one additional correlation of an additional sample point of the at least one sample point across the reference basket array; and when the correlation quality does achieve a pre-determined quality threshold, calculating a position error based on the correlating of the first sample point and any additional correlations of any additional sample points.

Abstract: A navigation system includes an inertial navigation unit. The navigation system also includes a Kalman filter that generates corrective feedback for use by the inertial navigation unit. The Kalman filter generates the corrective feedback as a function of at least one of GPS/DGPS information, sensor information, user input, terrain correlation information, signal-of-opportunity information, and/or position information output by a motion classifier.