# US 9,903,719 B2 · System and method for advanced navigation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,903,719 B2 - Document ID: US9903719B2 - Status: Granted - Kind: B2 - Application number: 14/475,158 - Filed: 2014-09-02 - Published: 2017-01-26 - Granted: 2018-02-27 - Earliest claimed: 2013-09-03 - Assignees: Litel Instruments - Applicants: Litel Instruments - Inventors: Robert O. Hunter, Jr.; Adlai H. Smith - Web page: https://patentgrep.com/patent/US9903719B2 ## CPC - G01C 21/005: {with correlation of navigation data from several sources, e.g. map or contour matching (G01C21/30 takes precedence)} - G01S 19/45: by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement - G01S 19/47: the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial - G06T 7/74: {involving reference images or patches} - G08G 5/50: Navigation or guidance aids - G08G 5/55: for a single aircraft - G06T 2207/10024: Color image - G06T 2207/10032: Satellite or aerial image; Remote sensing - G06T 2207/30184: Infrastructure - G06T 2207/30252: Vehicle exterior; Vicinity of vehicle - G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S) - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - G08G: TRAFFIC CONTROL SYSTEMS (guiding railway traffic, ensuring the safety of railway traffic B61L; arrangement of road signs or traffic signals E01F9/00; radar or analogous systems, sonar systems, lidar systems specially adapted for traffic control G01S13/91, G01S15/88, G01S17/88; {radar or analogous systems, sonar systems, lidar systems specially adapted for anti-collision purposes G01S13/93, G01S15/93, G01S17/93}) ## Abstract Systems and methods relating to assessing a navigation subsystem are provided. One method includes: acquiring a ground image associated with a nominal position; assigning one or more texture classes to each of a plurality of pixels of the ground image; partitioning the processed ground image into a plurality of ground image sub regions; retrieving a reference image from an atlas of reference images; generating a plurality of matching statistics comprising a matching statistic for each ground image sub region by comparing the ground image sub region to a portion of the reference image; calculating a calculated position of the ground image and an uncertainty associated with the calculated position based on the matching statistics; and determining critique data associated with the navigation subsystem based on a comparison of the calculated position of the ground image with at least one position determined by the navigation subsystem. ## Claims ### Claim 1 A navigation system comprising: one or more navigation subsystems configured to determine a position of a platform; a first processor configured to receive one or more outputs of the one or more navigation subsystems and generate a navigation solution; a sensor configured to generate a ground image; and a second processor configured to: process the ground image into one or more of a plurality of textures to generate a processed ground image; determine an estimated location of the ground image; partition the processed ground image into a plurality of ground image sub regions; retrieve a reference image from an atlas of reference images, each reference image in the atlas having an associated accuracy, resolution, and projection, the reference image having a position, projection, and extent determined based on the estimated location and a ground image projection of the ground image; generate a plurality of matching statistics comprising a matching statistic for each ground image sub region by comparing the ground image sub region to a portion of the reference image; calculate a relative position of the ground image with respect to the reference image based on the matching statistics; determine critique data associated with at least one of the one or more navigation subsystems based on the relative position of the ground image with respect to the reference image and a position of the ground image determined using the at least one navigation subsystem, the critique data comprising at least one of an error or a status of the at least one navigation subsystem based on an analysis of the position of the ground image determined using the at least one navigation subsystem in view of the relative position of the ground image with respect to the reference image; and transmit the critique data to the first processor; wherein the first processor is further configured to adjust one or more parameters associated with the at least one navigation subsystem based on the critique data, the first processor configured to generate the navigation solution using the adjusted one or more parameters. ### Claim 2 (depends on 1) The navigation system of claim 1, the platform comprising an aircraft, the at least one navigation subsystem comprising a flight navigation system, the first processor comprising a flight computer, and the second processor comprising a ground point positioning processor. ### Claim 3 (depends on 1) The navigation system of claim 1, the platform comprising a ground-based vehicle, the at least one navigation subsystem comprising a ground navigation system, the first processor comprising a ground navigation computer, and the second processor comprising a ground point positioning processor. ### Claim 4 (depends on 1) The navigation system of claim 1, wherein the second processor is further configured to store a history of at least one of one or more navigation subsystem solutions associated with one or more of the navigation subsystems or a combined navigation solution generated using two or more navigation subsystems. ### Claim 5 (depends on 1) The navigation system of claim 1, wherein the second processor is further configured to determine whether the ground image is suitable for matching to the reference image. ### Claim 6 (depends on 1) The navigation system of claim 1, wherein the second processor is further configured to determine an estimated location error associated with the ground image. ### Claim 7 (depends on 1) The navigation system of claim 1, wherein the second processor is further configured to determine and apply a down sampling ratio to the ground image prior to partitioning the processed ground image. ### Claim 8 (depends on 1) The navigation system of claim 1, wherein the second processor is further configured to calculate an uncertainty in position of the ground image with respect to the reference image and determine the critique data based on the uncertainty in position. ### Claim 9 (depends on 1) The navigation system of claim 1, further comprising a link between the second processor and the first processor through which the second processor transmits the critique data to the first processor. ### Claim 10 A navigation system comprising: a processor configured to: store a history of navigation solutions associated with one or more navigation subsystems configured to determine a position of a platform; acquire a ground image from a sensor; process the ground image into one or more of a plurality of textures to generate a processed ground image; determine an estimated location of the ground image and an estimated location error associated with the estimated location; apply a down sampling ratio to the processed ground image; partition the processed ground image into a plurality of ground image sub regions; retrieve a reference image from an atlas of reference images, each reference image in the atlas having an associated accuracy, resolution, and projection, the reference image having a position, projection, and extent determined based on the estimated location and a ground image projection of the ground image; generate a plurality of matching statistics comprising a matching statistic for each ground image sub region by comparing the ground image sub region to a portion of the reference image; calculate a relative position of the ground image with respect to the reference image based on the matching statistics; determine critique data associated with at least one of the one or more navigation subsystems based on the relative position of the ground image with respect to the reference image and a position of the ground image determined using the at least one navigation subsystem, the critique data comprising at least one of an error or a status of the at least one navigation subsystem based on an analysis of the position of the ground image determined using the at least one navigation subsystem in view of the relative position of the ground image with respect to the reference image; and transmit the critique data to a second processor configured to adjust one or more parameters associated with the at least one navigation subsystem based on the critique data, the second processor configured to generate the navigation solution using the adjusted one or more parameters.