# US 9,435,635 B1 · System and methods of detecting an intruding object in a relative navigation system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,435,635 B1 - Document ID: US9435635B1 - Status: Granted - Kind: B1 - Application number: 14/633,231 - Filed: 2015-02-27 - Published: 2016-09-01 - Granted: 2016-09-06 - Earliest claimed: 2015-02-27 - Assignees: GE Aviation Systems LLC - Applicants: GE Aviation Systems LLC - Inventors: Michael Steven Feldmann; Frank Saggio, III; Timothy John Paasche; Mark Lawrence Turner; John Andrew Ingersoll - Web page: https://patentgrep.com/patent/US9435635B1 ## CPC - G01B 11/002: {for measuring two or more coordinates} - G01S 5/16: using electromagnetic waves other than radio waves - G01S 7/003: {Transmission of data between radar, sonar or lidar systems and remote stations} - G01S 17/003: {Bistatic lidar systems; Multistatic lidar systems} - G01S 17/46: Indirect determination of position data - G01S 17/933: of aircraft or spacecraft - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - 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 ## Abstract A relative navigation system and methods of intrusion detection for such a relative navigation system where the method includes repeatedly projecting from a grid generator a set of lines defining a grid into three dimensional space to define a field bounded by the grid and encoded with grid data configured to identify predetermined points on the grid and determining a presence of an intruding object within the field. ## Claims ### Claim 1 A method of intrusion detection for a relative navigation system, the method comprising: repeatedly projecting, from a grid generator, a set of lines defining a grid in three dimensional space to define a field bounded by the projected grid and encoded with grid data configured to identify predetermined points on the grid; and determining a presence of an intruding object within the field. ### Claim 2 (depends on 1) The method of claim 1 wherein determining the presence of the intruding object includes detecting retro-reflected light or backscattered light reflected from the intruding object. ### Claim 3 (depends on 2) The method of claim 2 wherein determining the presence of the intruding object further includes forming a point cloud image from the detected light. ### Claim 4 (depends on 3) The method of claim 3 wherein the point cloud image is processed and the intruding object is identified. ### Claim 5 (depends on 1) The method of claim 1 wherein determining the presence of the intruding object includes detecting a multi-path reflection of at least a portion of the projected grid deflecting off the intruding object, by a detector module that is an intended receiver of the grid. ### Claim 6 (depends on 1) The method of claim 1 wherein determining the presence of the intruding object includes detecting that a portion of the generated grid is blocked or detecting a reduction in light intensity from the grid by a detector module that is an intended receiver of the grid. ### Claim 7 (depends on 1) The method of claim 1, further comprising projecting light, from a secondary light source, into the field and determining the presence of the intruding object based upon a reflection of the light. ### Claim 8 (depends on 1) The method of claim 1 wherein the projecting light from the secondary light source occurs between projections of the grid from the grid generator. ### Claim 9 (depends on 1) The method of claim 1 wherein determining the presence of the intruding object further includes determining an azimuth, elevation, or range of the intruding object from the grid generator. ### Claim 10 (depends on 1) The method of claim 1, further comprising classifying the intruding object as an obstacle to be avoided or a known object that provides a marker. ### Claim 11 A method of detecting an intruding object, the method comprising: repeatedly projecting, from a grid generator located on a transmitting object, a set of lines defining a grid and encoded with grid data configured to identify predetermined points on the grid; receiving at least a portion of the projected grid on a detector module located on the receiving object; and determining a presence of an intruding object located within the grid and between the transmitting and receiving objects based on at least one characteristic of the projected grid. ### Claim 12 (depends on 11) The method of claim 11 wherein determining the presence of the intruding object includes detecting that a portion of the grid has been blocked by the intruding object. ### Claim 13 A relative navigation system, comprising: a grid generator projecting into three dimensional space a relative navigation grid to define a field; and a detector module for detecting light and configured to output a signal related to the detected light; and a processor operably coupled to the detector module and configured to receive the signal and determine when the signal related to the detected light is indicative of the presence of an intruding object. ### Claim 14 (depends on 13) The system of claim 13 wherein the detector module is located near the grid generator. ### Claim 15 (depends on 14) The system of claim 14 wherein the detector module detects retro-reflected light or backscattered light reflected from the intruding object. ### Claim 16 (depends on 13) The system of claim 13 wherein the processor receives a signal related to the detected light and forms a point cloud image therefrom. ### Claim 17 (depends on 13) The system of claim 13 wherein the detector module is operably coupled to a receiving object that is an intended receiver of the grid and the detector module is configured to detect a multi-path reflection or a loss of light from the grid. ### Claim 18 (depends on 13) The system of claim 13, further comprising a secondary light source and wherein the detector module determines the presence of the intruding object based on a projection of the secondary light source. ### Claim 19 (depends on 18) The system of claim 18 wherein the secondary light source includes an unscanned laser dot, a scanned laser dot, or a flash laser. ### Claim 20 (depends on 13) The system of claim 13 wherein the processor is configured to determine an azimuth, elevation, or range of the intruding object from the grid generator.