# US 2018/0321041 A1 · Methods and systems for determining a state of an unmanned aerial vehicle > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0321041 A1 - Document ID: US20180321041A1 - Status: Published application - Kind: A1 - Application number: 16/029,960 - Filed: 2018-07-09 - Published: 2018-11-08 - Earliest claimed: 2014-03-24 - Assignees: Sz Dji Technology Co., Ltd. - Applicants: Sz Dji Technology Co., Ltd. - Inventors: Guyue ZHOU; Shuo YANG; Ang LIU - Web page: https://patentgrep.com/patent/US20180321041A1 ## CPC - G01C 21/20: Instruments for performing navigational calculations (G01C21/24, G01C21/26 take precedence) - G05D 1/102: {specially adapted for vertical take-off of aircraft} - B64U 10/13: Flying platforms - B64U 2101/30: for imaging, photography or videography - B64U 2201/10: autonomous, i.e. by navigating independently from ground or air stations, e.g. by using inertial navigation systems [INS] - 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) - G05D: SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES - B64U: UNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR ## Abstract A method for determining an external state of an unmanned aerial vehicle (UAV) includes obtaining historical external state information of the UAV, obtaining a current image and a historical image captured before the current image, predicting a matching feature point in the current image that corresponds to a target feature point in the historical image according the historical external state information, and determining the external state of the UAV based on the matching feature point. ## Claims ### Claim 1 A method for determining an external state of an unmanned aerial vehicle (UAV) comprising: obtaining historical external state information of the UAV; obtaining a current image and a historical image captured before the current image; predicting, according the historical external state information, a matching feature point in the current image that corresponds to a target feature point in the historical image; and determining the external state of the UAV based on the matching feature point. ### Claim 2 (depends on 1) The method of claim 1, wherein the external state includes a distance of the UAV relative to an external object. ### Claim 3 (depends on 1) The method of claim 1, wherein obtaining the historical external state information includes obtaining at least one of distance information of the UAV relative to one or more external objects, position information of the one or more external object, position information of the UAV, or a feature point associated with a set of coordinates under a reference model. ### Claim 4 (depends on 1) The method of claim 1, wherein obtaining the current image and the historical image includes obtaining the current image and the historical image from a series of images captured by a monocular camera. ### Claim 5 (depends on 1) The method of claim 1, wherein obtaining the current image includes obtaining the current image in real time from a monocular camera. ### Claim 6 (depends on 1) The method of claim 1, wherein obtaining the historical image includes reading the historical image from a memory onboard the UAV that stores the series of captured images. ### Claim 7 (depends on 1) The method of claim 1, wherein obtaining the historical image includes receiving the historical image from a remote terminal. ### Claim 8 (depends on 1) The method of claim 1, wherein: obtaining the historical external state information includes obtaining information characterizing a motion vector associated with the UAV; and predicting the matching feature point includes predicting the matching feature point according to the motion vector. ### Claim 9 (depends on 8) The method of claim 8, wherein obtaining the information characterizing the motion vector associated with the UAV includes obtaining at least one of a direction or a speed of the UAV. ### Claim 10 (depends on 1) The method of claim 1, wherein predicting the matching feature point includes: predicting a coordinate position of the target feature point in the current image according to the historical external state information; and selecting, from one or more feature points in the current image, a feature point that is closest to the predicted coordinate position as the matching feature point. ### Claim 11 A system for controlling an unmanned aerial vehicle comprising: a processor; and a memory storing program instructions that, when executed by the processor, cause the processor to: obtain historical external state information of the UAV; obtain a current image and a historical image captured before the current image; predict, according the historical external state information, a matching feature point in the current image that corresponds to a target feature point in the historical image; and determine the external state of the UAV based on the matching feature point. ### Claim 12 (depends on 11) The system of claim 11, wherein the external state includes a distance of the UAV relative to an external object. ### Claim 13 (depends on 11) The system of claim 11, wherein the historical external state information includes at least one of distance information of the UAV relative to one or more external objects, position information of the one or more external object, position information of the UAV, or a feature point associated with a set of coordinates under a reference model. ### Claim 14 (depends on 11) The system of claim 11, wherein the instructions further cause the processor to obtain the current image and the historical image from a series of images captured by a monocular camera. ### Claim 15 (depends on 11) The system of claim 11, wherein the instructions further cause the processor to obtain the current image in real time from a monocular camera. ### Claim 16 (depends on 11) The system of claim 11, wherein the instructions further cause the processor to read the historical image from a storage memory onboard the UAV that stores the series of captured images. ### Claim 17 (depends on 11) The system of claim 11, wherein the instructions further cause the processor to receive the historical image from a remote terminal. ### Claim 18 (depends on 11) The system of claim 11, wherein the instructions further cause the processor to: obtain information characterizing a motion vector associated with the UAV as the historical external state information; and predict the matching feature point according to the motion vector. ### Claim 19 (depends on 18) The system of claim 18, wherein the motion vector associated with the UAV includes at least one of a direction or a speed of the UAV. ### Claim 20 (depends on 11) The system of claim 11, wherein the instructions further cause the processor to: predict a coordinate position of the target feature point in the current image according to the historical external state information; and select, from one or more feature points in the current image, a feature point that is closest to the predicted coordinate position as the matching feature point.