Tight optical integration (TOI) of images with GPS range measurements
First Claim
1. A method of determining a position of a user in 3D space utilizing an integrated navigation system including a GPS receiver and a camera located at the user position when a limited number of GPS signals are available, the method comprising:
- capturing, by the camera, a camera image of a known marker through a focal point of the camera with optical measurements that extend from a position of the known marker within the camera image to the user position of the camera;
determining two or more pseudoranges between a true user position and two or more GPS satellites with the integrated navigation system, wherein the two or more GPS satellites are insufficient to generate GPS measurements necessary to calculate a GPS standalone position;
determining a marker unit vector from the optical measurements captured by at least one optic sensor associated with the camera that extends from the position within the camera image associated with the known marker through the focal point of the camera with the integrated navigation system, wherein unavailable GPS measurements necessary to calculate the GPS standalone position are replaced by the marker unit vector;
converting, by the GPS receiver, the marker unit vector from a camera frame of reference to an earth frame of reference of GPS measurements by incorporating attitude information of the camera obtained from inertial measurements of the camera at the user position to transform a direction cosine of the marker unit vector in the camera frame of reference to the earth frame of reference;
integrating, by the GPS receiver, the two or more pseudoranges and the marker unit vector into an ordinary least squares matrix with the integrated navigation system;
generating a shortest vector starting from an estimated user position to a point on the marker unit vector, wherein the shortest vector is perpendicular to the marker unit vector at the point on the marker unit vector;
converging, by the GPS receiver, a line joining the estimated user position and the marker and the two or more pseudoranges derived from the estimated user position to the point on the marker unit vector generated from the shortest vector being perpendicular to the marker unit vector;
determining the position of the user in 3D space from the convergence of the line joining the estimated user position and the two or more pseudoranges derived from the estimated user position to the point on the marker unit vector generated from the shortest vector being perpendicular to the marker unit vector by solving the ordinary least squares matrix with the integrated navigation system so that the two or more pseudoranges are supplemented with the marker unit vector to overcome the unavailable GPS measurements to calculate the GPS standalone position.
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Abstract
A method of determining the position of a user in 3D space is disclosed. In one example, the method comprises utilizing range measurements from one or more GPS satellite vehicles, angular information of a camera located at the user position, and a camera image associated with one or more known markers. The method further comprises determining the angular information of the camera by determining a direction cosine matrix between a camera frame of reference and an earth frame of reference, and designating unit vectors that individually extend from a position within the camera image associated with one of the known markers through the camera focal point to the respective known marker The method also includes integrating into an ordinary least squares matrix, the GPS range measurements, the angular information of the camera, and the unit vectors, and calculating the user position by solving the ordinary least squares matrix.
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Citations
22 Claims
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1. A method of determining a position of a user in 3D space utilizing an integrated navigation system including a GPS receiver and a camera located at the user position when a limited number of GPS signals are available, the method comprising:
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capturing, by the camera, a camera image of a known marker through a focal point of the camera with optical measurements that extend from a position of the known marker within the camera image to the user position of the camera; determining two or more pseudoranges between a true user position and two or more GPS satellites with the integrated navigation system, wherein the two or more GPS satellites are insufficient to generate GPS measurements necessary to calculate a GPS standalone position; determining a marker unit vector from the optical measurements captured by at least one optic sensor associated with the camera that extends from the position within the camera image associated with the known marker through the focal point of the camera with the integrated navigation system, wherein unavailable GPS measurements necessary to calculate the GPS standalone position are replaced by the marker unit vector; converting, by the GPS receiver, the marker unit vector from a camera frame of reference to an earth frame of reference of GPS measurements by incorporating attitude information of the camera obtained from inertial measurements of the camera at the user position to transform a direction cosine of the marker unit vector in the camera frame of reference to the earth frame of reference; integrating, by the GPS receiver, the two or more pseudoranges and the marker unit vector into an ordinary least squares matrix with the integrated navigation system; generating a shortest vector starting from an estimated user position to a point on the marker unit vector, wherein the shortest vector is perpendicular to the marker unit vector at the point on the marker unit vector; converging, by the GPS receiver, a line joining the estimated user position and the marker and the two or more pseudoranges derived from the estimated user position to the point on the marker unit vector generated from the shortest vector being perpendicular to the marker unit vector; determining the position of the user in 3D space from the convergence of the line joining the estimated user position and the two or more pseudoranges derived from the estimated user position to the point on the marker unit vector generated from the shortest vector being perpendicular to the marker unit vector by solving the ordinary least squares matrix with the integrated navigation system so that the two or more pseudoranges are supplemented with the marker unit vector to overcome the unavailable GPS measurements to calculate the GPS standalone position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A navigation system comprising:
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a camera that includes at least one optic sensor; and a GPS receiver operatively coupled to the camera, the navigation system when a limited number of GPS signals are available is configured to; determine two or more pseudoranges between a true user position and two or more GPS satellites, wherein the two or more GPS satellites are insufficient to generate GPS measurements necessary to calculate a GPS standalone position; determine a marker unit vector from optical measurements captured by the at least one optic sensor included in the camera that extends from a position within a camera image associated with a known marker through a focal point of the camera, wherein unavailable GPS measurements necessary to calculate the GPS standalone position are replaced by the marker unit vector; convert the marker unit vector from a camera frame of reference to an earth frame of reference of GPS measurements by incorporating attitude information of the camera obtained from inertial measurements of the camera at the user position to transform a direction cosine of the marker unit vector in the camera frame of reference to the earth frame of reference; integrate the two or more pseudoranges and the marker unit vector into an ordinary least squares matrix; generate a shortest vector starting from an estimated user position to a point on the marker unit vector, wherein the shortest vector is perpendicular to the marker unit vector at the point on the marker unit vector; and converge a line joining the estimated user position and the marker and the two or more pseudoranges derived from the estimated user position to the point on the market unit vector generated from the shortest vector being perpendicular to the marker unit vector; and determine the position of the user in 3D space from the convergence of the line joining the estimated user position and the marker and the two or more pseudoranges derived from the estimated user position to the point on the marker unit vector generated from the shortest vector being perpendicular to the marker unit vector by solving the ordinary least squares matrix so that the two or more pseudoranges are supplemented with the marker unit vector to overcome the unavailable GPS measurements to calculate the GPS standalone position. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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Specification