# US 2021/0241636 A1 · Tether management systems and methods > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0241636 A1 - Document ID: US20210241636A1 - Status: Published application - Kind: A1 - Application number: 17/148,500 - Filed: 2021-01-13 - Published: 2021-08-05 - Earliest claimed: 2020-01-19 - Assignees: FLIR Unmanned Aerial Systems ULC - Applicants: FLIR Unmanned Aerial Systems ULC - Inventors: Fei Yu; Richard Cunha; Jerry Mailloux - Web page: https://patentgrep.com/patent/US20210241636A1 ## CPC - G08G 5/22: located on the ground - G08G 5/55: for a single aircraft - B64U 10/60: Tethered aircraft - G05D 1/0866: {specially adapted to captive aircraft} - G08G 5/23: Details of user output interfaces, e.g. information presented - G08G 5/26: Transmission of traffic-related information between aircraft and ground stations - G08G 5/53: for cruising - G08G 5/57: for unmanned aircraft - B64U 10/13: Flying platforms - B64U 2101/20: for use as communications relays, e.g. high-altitude platforms - B64U 2101/32: for cartography or topography - B64U 2201/00: UAVs characterised by their flight controls - B64U 2201/202: using tethers for connecting to ground station - 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}) - B64U: UNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR - G05D: SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES ## Abstract Unmanned aircraft systems (UASs) and related techniques are provided to improve the operation of unmanned mobile sensor or survey platforms. A tether management system includes a logic device configured to communicate with a communication module and an orientation sensor coupled to a tethered unmanned aerial vehicle (UAV), wherein the communication module is configured to establish a communication link with a base station associated with the tethered UAV, the orientation sensor is configured to provide headings of the tethered UAV as it maneuvers within a survey area. The logic device is configured to determine an accumulated twist of a tether coupled between the base station and the tethered UAV and generate a tether damage warning notification based, at least in part, on the determined accumulated twist and a maximum allowable accumulated twist associated with the tether coupled between the base station and the tethered UAV. ## Claims ### Claim 1 A system comprising: a logic device configured to communicate with a communication module and an orientation sensor coupled to a tethered unmanned aerial vehicle (UAV), wherein the communication module is configured to establish a communication link with a base station associated with the tethered UAV, the orientation sensor is configured to provide headings of the tethered UAV as it maneuvers within a survey area, and the logic device is configured to: receive heading data from the orientation sensor corresponding to one or more positions of the tethered UAV within the survey area; determine an accumulated twist of a tether coupled between the base station and the tethered UAV, wherein the accumulated twist of the tether is based, at least in part, on the received heading data; and generate a tether damage warning notification based, at least in part, on the determined accumulated twist and a maximum allowable accumulated twist associated with the tether coupled between the base station and the tethered UAV. ### Claim 2 (depends on 1) The system of claim 1, wherein the logic device is configured to: autopilot the tethered UAV to counteryaw the tethered UAV to reduce the accumulated twist of the tether coupled between the base station and the tethered UAV. ### Claim 3 (depends on 2) The system of claim 2, wherein the logic device is configured to: generate a tether untwisting process initiation notification prior to the autopiloting the tethered UAV to reduce the accumulated twist of the tether. ### Claim 4 (depends on 2) The system of claim 2, wherein the logic device is configured to: determine an initial heading of the tethered UAV prior to autopiloting the tethered UAV to reduce the accumulated twist of the tether; and autopilot the tethered UAV to orient the tethered UAV according to the initial heading. ### Claim 5 (depends on 4) The system of claim 4, wherein the logic device is configured to: generate a tether untwisting process completed notification subsequent to the autopiloting the tethered UAV to reduce the accumulated twist of the tether and/or subsequent to the autopiloting the tethered UAV to orient the tethered UAV according to the initial heading. ### Claim 6 (depends on 1) The system of claim 1, wherein the determining the accumulated twist of the tether comprises: determining an accumulated yaw of the tethered UAV based on the received heading data corresponding to the one or more positions of the tethered UAV within the survey area; and determining the accumulated twist of the tether as the absolute value of the accumulated yaw of the tethered UAV divided by 360 degrees. ### Claim 7 (depends on 1) The system of claim 1, wherein the logic device is configured to determine the maximum allowable accumulated twist prior to generating the tether damage warning notification, wherein the determining the maximum allowable accumulated twist comprises: receiving an unspooled length of the tether from a tether management system of the base station; retrieving a predetermined maximum allowable twist associated with the tether; and determining the maximum allowable accumulated twist as the maximum allowable twist multiplied by the unspooled length of the tether. ### Claim 8 (depends on 1) The system of claim 1, wherein the logic device is configured to determine the maximum allowable accumulated twist prior to generating the tether damage warning notification, wherein the determining the maximum allowable accumulated twist comprises: determining a flight altitude estimate of the tethered UAV; retrieving a predetermined maximum allowable twist associated with the tether; and determining the maximum allowable accumulated twist as the maximum allowable twist multiplied by the flight altitude estimate. ### Claim 9 (depends on 1) The system of claim 1, wherein: the logic device is coupled to the tethered UAV; and the tether damage warning notification is received from the base station over the communication link. ### Claim 10 (depends on 1) The system of claim 1, wherein: the logic device is coupled to the base station; and the tether damage warning notification is received from the UAV over the communication link. ### Claim 11 A method comprising: receiving heading data from the orientation sensor coupled to a tethered unmanned aerial vehicle (UAV) configured to provide headings of the tethered UAV as it maneuvers within a survey area, wherein the heading data corresponds to one or more positions of the tethered UAV within a survey area; determining an accumulated twist of a tether coupled between a base station and the tethered UAV, wherein the accumulated twist of the tether is based, at least in part, on the received heading data; and generating a tether damage warning notification based, at least in part, on the determined accumulated twist and a maximum allowable accumulated twist associated with the tether coupled between the base station and the tethered UAV. ### Claim 12 (depends on 11) The method of claim 11, further comprising: autopilot the tethered UAV to counteryaw the tethered UAV to reduce the accumulated twist of the tether coupled between the base station and the tethered UAV. ### Claim 13 (depends on 12) The method of claim 12, further comprising: generate a tether untwisting process initiation notification prior to the autopiloting the tethered UAV to reduce the accumulated twist of the tether. ### Claim 14 (depends on 12) The method of claim 12, further comprising: determine an initial heading of the tethered UAV prior to autopiloting the tethered UAV to reduce the accumulated twist of the tether; and autopilot the tethered UAV to orient the tethered UAV according to the initial heading. ### Claim 15 (depends on 14) The method of claim 14, further comprising: generate a tether untwisting process completed notification subsequent to the autopiloting the tethered UAV to reduce the accumulated twist of the tether and/or subsequent to the autopiloting the tethered UAV to orient the tethered UAV according to the initial heading. ### Claim 16 (depends on 11) The method of claim 11, wherein the determining the accumulated twist of the tether comprises: determining an accumulated yaw of the tethered UAV based on the received heading data corresponding to the one or more positions of the tethered UAV within the survey area; and determining the accumulated twist of the tether as the absolute value of the accumulated yaw of the tethered UAV divided by 360 degrees. ### Claim 17 (depends on 11) The method of claim 11, further comprising determining the maximum allowable accumulated twist prior to the generating the tether damage warning notification, wherein the determining the maximum allowable accumulated twist comprises: receiving an unspooled length of the tether from a tether management system of the base station; retrieving a predetermined maximum allowable twist associated with the tether; and determining the maximum allowable accumulated twist as the maximum allowable twist multiplied by the unspooled length of the tether. ### Claim 18 (depends on 11) The method of claim 11, wherein further comprising determining the maximum allowable accumulated twist prior to the generating the tether damage warning notification, wherein the determining the maximum allowable accumulated twist comprises: determining a flight altitude estimate of the tethered UAV; retrieving a predetermined maximum allowable twist associated with the tether; and determining the maximum allowable accumulated twist as the maximum allowable twist multiplied by the flight altitude estimate. ### Claim 19 (depends on 11) The method of claim 11, wherein: the tether damage warning notification is received from the base station over a communication link established over the tether. ### Claim 20 (depends on 11) The method of claim 11, wherein: the tether damage warning notification is received from the UAV over the communication link established over the tether.