Abstract: Techniques are provided for image-based estimation of the orientation of an airborne platform. A methodology implementing the techniques according to an embodiment includes rotating an image, provided by a camera on the platform, by a selected rotation angle. The method also includes computing an intensity gradient image based on the rotated image. The method further includes extracting a left quarter segment and a right quarter segment of the intensity gradient image. The method further includes flipping one of the extracted segments about a vertical axis through that segment and comparing the non-flipped segment to the flipped segment to generate a matching score. The comparison may be based on a correlation between the flipped segment and the non-flipped segment. The process may be repeated for additional rotation angles and the rotation angle associated with the highest matching score is selected as the estimated orientation angle of the platform.

Abstract: Techniques are provided for image-based estimation of the orientation of an airborne platform. A methodology implementing the techniques according to an embodiment includes rotating an image, provided by a camera on the platform, by a selected rotation angle. The method also includes computing an intensity gradient image based on the rotated image. The method further includes extracting a left quarter segment and a right quarter segment of the intensity gradient image. The method further includes flipping one of the extracted segments about a vertical axis through that segment and comparing the non-flipped segment to the flipped segment to generate a matching score. The comparison may be based on a correlation between the flipped segment and the non-flipped segment. The process may be repeated for additional rotation angles and the rotation angle associated with the highest matching score is selected as the estimated orientation angle of the platform.

Abstract: A navigation path planning method includes receiving an initial position of a navigation path and a terminal position of the navigation path. The initial position represents a current position of a vehicle or other platform that is navigating to the terminal or target position. The method includes calculating the navigation path from the initial position to the terminal position as an objective function of a navigation reliability term and a navigation accuracy term. The navigation reliability term represents a probability of successfully reaching the terminal position along the navigation path, and the navigation accuracy term represents the probable distance between the terminal position and the navigation path. The calculated navigation path is provided to a navigation system to cause the platform to navigate along the calculated navigation path.

Abstract: An ensemble of motion sensors is tested under known conditions to automatically ascertain instrument biases, which are modeled as autoregressive-moving-average (ARMA) processes in order to construct a Kalman filter. The calibration includes motion profiles, temperature profiles and vibration profiles that are operationally significant, i.e., designed by means of covariance analysis or other means to maximize, or at least improve, the observability of the calibration model's structure and coefficients relevant to the prospective application of each sensor.

Abstract: A probabilistic landmark navigation system is arranged to obtain from one or more image sensors one or more terrain images of a target terrain to be traversed by a vehicle. The terrain images are characterized by multiple individually non-distinctive terrain features without distinctively identifiable landmark features. The non-distinctive terrain features in the one or more terrain images are compared to map database information to make a non-temporal probabilistic determination of absolute location coordinates to associate with the non-distinctive terrain features. Then a navigation path is determined for the vehicle across the target terrain based on the absolute location coordinates.

Abstract: Methods for use in celestial navigation system use multiple star observations from an unknown observer location using an observer camera with an observational field of view along a boresight axis and a focal plane perpendicular to the boresight axis. An observer local ECI coordinate system is determined from the star observations. Then for each of multiple observable objects in orbit around the Earth, multiple optical angular measurements relative to stars are performed over time to estimate its orbital ellipse, and its focus at the center of the Earth. From the multiple focus estimates, a position of the center of the Earth is estimated in the observer local coordinate system without use of object ephemeris data. From the estimated position of the center of the Earth, a radius vector to the observer is determined that represents the estimated observer location in Earth centered Earth fixed coordinates.

Abstract: A visual navigation system includes a compass configured to orient a user in a heading direction, an image sensor configured to capture a series of successive navigation images in the heading direction, one or more of the navigation images having at least two reference markers, data storage memory configured to store the series of successive navigation images, a navigation processor configured to identify at least one principal marker and at least one ancillary marker from the at least two reference markers, the principal marker positioned within a principal angle and the ancillary marker positioned within an ancillary angle, which is greater than the principal angle, and to determine heading direction information based on a position of the at least one principal marker and/or the at least one ancillary marker in the successive navigation images, and a user interface configured to provide the heading direction information to the user.

Abstract: A method is described for determining roll rate for a spin-stabilized projectile. A yaw signal and a pitch signal are measured for the projectile, wherein: (i) for a trajectory path being travelled by the projectile over the Earth's surface, projectile stability is created by spinning of the projectile about a longitudinal spin axis oriented tangent to the projectile trajectory, (ii) the yaw signal represents yaw motion of the projectile about a yaw axis oriented along a line through the Earth's center and orthogonal to the spin axis, and (iii) the pitch signal represents pitch motion of the projectile about a pitch axis orthogonal to the spin axis and the yaw axis, and wherein the yaw signal and the pitch signal are modulated by spin rate of the projectile spinning about the spin axis. A roll rate signal is extracted from one of the yaw signal and the pitch signal.

Abstract: A probabilistic landmark navigation system is arranged to obtain from one or more image sensors one or more terrain images of a target terrain to be traversed by a vehicle. The terrain images are characterized by multiple individually non-distinctive terrain features without distinctively identifiable landmark features. The non-distinctive terrain features in the one or more terrain images are compared to map database information to make a non-temporal probabilistic determination of absolute location coordinates to associate with the non-distinctive terrain features. Then a navigation path is determined for the vehicle across the target terrain based on the absolute location coordinates.

Abstract: A visual navigation system includes a compass configured to orient a user in a heading direction, an image sensor configured to capture a series of successive navigation images in the heading direction, one or more of the navigation images having at least two reference markers, data storage memory configured to store the series of successive navigation images, a navigation processor configured to identify at least one principal marker and at least one ancillary marker from the at least two reference markers, the principal marker positioned within a principal angle and the ancillary marker positioned within an ancillary angle, which is greater than the principal angle, and to determine heading direction information based on a position of the at least one principal marker and/or the at least one ancillary marker in the successive navigation images, and a user interface configured to provide the heading direction information to the user.

Abstract: An ensemble of motion sensors is tested under known conditions to automatically ascertain instrument biases, which are modeled as autoregressive-moving-average (ARMA) processes in order to construct a Kalman filter. The calibration includes motion profiles, temperature profiles and vibration profiles that are operationally significant, i.e., designed by means of covariance analysis or other means to maximize, or at least improve, the observability of the calibration model's structure and coefficients relevant to the prospective application of each sensor.