Classifications

• • G—PHYSICS
  • G08—SIGNALLING
  • G08G—TRAFFIC CONTROL SYSTEMS
  • G08G5/00—Traffic control systems for aircraft, e.g. air-traffic control [ATC]
  • G08G5/0047—Navigation or guidance aids for a single aircraft
  • G08G5/0069—Navigation or guidance aids for a single aircraft specially adapted for an unmanned aircraft
• • G—PHYSICS
  • G08—SIGNALLING
  • G08G—TRAFFIC CONTROL SYSTEMS
  • G08G5/00—Traffic control systems for aircraft, e.g. air-traffic control [ATC]
  • G08G5/0073—Surveillance aids
  • G08G5/0078—Surveillance aids for monitoring traffic from the aircraft
• • G—PHYSICS
  • G08—SIGNALLING
  • G08G—TRAFFIC CONTROL SYSTEMS
  • G08G5/00—Traffic control systems for aircraft, e.g. air-traffic control [ATC]
  • G08G5/04—Anti-collision systems
• • G—PHYSICS
  • G08—SIGNALLING
  • G08G—TRAFFIC CONTROL SYSTEMS
  • G08G5/00—Traffic control systems for aircraft, e.g. air-traffic control [ATC]
  • G08G5/04—Anti-collision systems
  • G08G5/045—Navigation or guidance aids, e.g. determination of anti-collision manoeuvers

Definitions

• the present invention relates to the prevention of collisions between aircraft and more particularly to a method of navigation and control of aerial drones.
• the invention also relates to a drone implementing such a method of navigation and control.
• An aerial drone is a human unmanned aircraft on board. This aircraft can be equipped with automated systems and perform its flight autonomously; it can also be provided with sensors connected to an automatic piloting device and / or to a remote control device by a pilot on the ground. Air drones are increasingly used in the military field, especially for battlefield surveillance, reconnaissance or even ground attack.
• TCAS anti-collision system
• ACAS anti-collision standard defined by the Convention on International Civil Aviation.
• the use of this system tends to be extended and all commercial aircraft with more than nineteen passenger seats must be equipped with version II of this system incorporating an S mode transponder.
• the system is arranged to recover information on the heading and the position of any aircraft, said intruder aircraft, evolving in the space surrounding the aircraft considered at a distance varying between 2.5 (4 km) and 30 miles (48 km). This information includes mainly the distance with these aircraft, their barometric altitude and approximate azimuth information.
• the information is retrieved by interrogating the Mode S transponder of the intruder aircraft and is used by the TCAS II system to determine whether a collision with this intruder aircraft is possible.
• the pilot of each aircraft is informed by a hearing alert issued in the cockpit. If the risk of collision is not reduced after this alert and the collision seems imminent, the TCAS system determines a maneuver set point for the pilot: maintain the current trajectory, climb, descend or monitor the vertical speed. hold.
• TCAS II system is, however, restrictive and unsuitable for UAVs that do not ship pilots and are generally of a relatively low cost.
• An object of the invention is to facilitate the navigation of a drone and increase its safety by allowing the taking into account of at least one intruder aircraft in the space surrounding the drone.
• a method of navigation of an aerial drone in the presence of at least one intruder aircraft in a zone of space surrounding the drone comprises the steps, implemented at the level of the drone, of:
• the positioning data can be the altitude of the intruder aircraft ⁇ the measured value being the transmitted altitude) or the angle of bearing of the intruder aircraft with respect to the drone (the measured value of the angle of view being that determined on the image ⁇ .
• the comparison of the estimated value and the measured value makes it possible to check the validity of the estimated distance between the drone and the intruder aircraft.
• the estimated and validated distance can then be taken into account in the navigation, in particular to foresee an avoidance maneuver of the intruding aircraft or to identify among the available information those which are the safest to use for navigation
• the drone it is not mandatory for the drone to be equipped with a transponder interrogator, the receiver of the drone receiving, for example, the signals transmitted by the mode C or S transponder of the aircraft i after being interrogated by either a secondary radar on the ground or by another aircraft equipped with an interrogator; the drone of the receiver can also receive, for example the transmitted signals automati cally ⁇ by a device type ADS-B (standing for "Automatic Dependent Surveillance-Broadcast").
• the method of the invention can therefore be implemented from solely passive sensors, in particular if the drone is brought to evolve only in an environment covered by secondary radars.
• the invention also relates to an aerial drone comprising a control device connected to an altitude measuring instrument, to an optronic detection device arranged to determine a bearing angle of an intruding aircraft operating in a surrounding area. the drone, and a receiver to receive a signal that is emitted by an intruder aircraft and that contains an altitude of the intruder aircraft.
• the piloting device of the drone is arranged for:
• FIG. 1 is a schematic perspective view of a crossing situation of an aircraft and a drone according to the invention
• FIG. 2 is a schematic view of the piloting device of the drone according to the invention.
• the aerial drone has the general shape of an aircraft and comprises a fuselage 1 and wings 2 which are provided with movable flight surfaces by means of actuators connected to a control device embedded in the aircraft. drone.
• the very structure of the drone is not part of the invention and will not be more detailed here.
• the steering system generally designated 3 comprises a data processing unit 4 connected to an altitude measuring instrument 5, to an optronic detection device 6 and to a receiver 7.
• the control device 3 also comprises in a manner known in itself. even means for controlling the actuators of the flight surfaces and the engine of the drone.
• the data processing unit 4 is a computer unit which notably comprises a processor for processing the data and a memory for recording the data.
• the altitude measuring instrument 5 is a conventional barometric instrument.
• the optronic detection device 6 comprises an image sensor connected to an acquisition unit and oriented to have a field covering a zone of monitored space located in front of the drone.
• the sensor of the detection device 6 is arranged to operate in the infrared range and / or in the visible range.
• the sensor has sufficient performance to detect, in the images provided, an aircraft (said intruder aircraft) located in the area of monitored space at a maximum distance of between 8 and 10 km.
• the processing unit 4 incorporates an image processing module (software or hardware) arranged to determine a bearing angle of the intruder aircraft operating in the area of monitored space.
• the receiver 7 has a directional antenna and is arranged to receive a signal that is transmitted by the mode S transponders of aircraft operating near the drone.
• the receiver operates here at the frequency of 1090 MHz.
• the signal contains: a barometric altitude of the intruder aircraft, a transponder code, and a hexadecimal code identifying each aircraft equipped with a mode S transponder.
• the control device 3 is arranged and grammed for:
• the processing unit 4 is programmed to implement Kalman filters in particular to calculate:
• the processing unit 4 also incorporates a module (software or hardware) for associating information derived solely from the received signal (transmitted altitude, estimated distance, estimated approximation speed, vertical speed) and derived information as well. images (estimated elevation speed, estimated altitude).
• a module software or hardware for associating information derived solely from the received signal (transmitted altitude, estimated distance, estimated approximation speed, vertical speed) and derived information as well. images (estimated elevation speed, estimated altitude).
• the optical device 6 When the drone A is in flight, the optical device 6 provides images to the processing unit 4 which processes these images to search for the presence of an intruder aircraft. As soon as an intruder C is detected by the image processing module in one of the images transmitted by the optronic device 6, the image processing module then determines in the image a bearing angle of the intruder aircraft. C present in the image.
• the drone A in flight receives signals from aircraft transponders responding to a secondary radar station B which is located on the ground S and which has a surveillance zone in which said aircraft and the drone A are moving. 4 of the drone A extracts the transmitted altitude contained in the signal, the identifier of the aircraft that emitted the signal and the power of the received signal.
• the estimated distance between the drone and the intruder aircraft is calculated by the Kalman filter from the power of the received signal and is transmitted to the association module.
• the estimated distance is also used by the processing unit 4 to calculate an estimated altitude of the intruder aircraft from the estimated distance and the bearing angle.
• control unit 3 is arranged to control the optronic device 6 in such a way that the reception of a signal automatically triggers the capture of an image by the optronic device 6.
• the estimated altitude is calculated in the local terrestrial reference (for example in the NED or ENU coordinate system).
• the accuracy of the estimated altitude depends on the proximity in time of signal reception and image capture.
• the power of the received signal is here used in the form of the signal-to-noise ratio of the received signal. This ratio depends on the distance between the transponder and the receiver, the transmission power (transponder from 1 to 5 Watts TBC), the gain of the transmitting antenna (antenna of the transponder of the intruder C aircraft), the gain of the receiver antenna 7, and the atmospheric attenuation. Nevertheless, it has been possible to determine experimentally that the distance can be approximated by a law of the second degree of the signal-to-noise ratio. The chosen law is valid on the range of distance considered, here between 1 and 10 km.
• the data that will be extracted from images of the intruder aircraft C or signals subsequently transmitted by the intruder aircraft C will be associated with said identifier.
• the Kalman filters of the processing unit 4 are arranged to calculate, from the estimated distances, a speed of approaching the intruder aircraft C and the drone A and an estimated time before a collision between the intruder aircraft C and the drone h.
• Kalman filters are designed to follow the evolution of data over time, to detect errors reduce the results.
• Transmitted altitudes, estimated distances, vi ⁇ tesses approximation of estimated (calculated by dif ferences ⁇ estimated distances over a given time), vi- vertical tesses (calculated by difference altitudes transmitted over a given time), the estimated heights (calculated from the estimated distances and bearing angles) and the estimated elevation rates are transmitted to the association module of the processing unit 4 which is arranged to associate this information with a data identification code such as as the identifier of the intruder aircraft (transmitted in the received signal).
• association module is arranged to perform a comparison of altitudes, that is to say:
• the processing unit 4 From the estimated time before collision, the processing unit 4 provides the control device 3 with an avoidance command, the avoidance command can be systematically the same (right turn or left turn) or be adapted for example taking into account the elevation speed of the intruding aircraft C (ascent or descent).
• association module retains as identifier the one for which the estimated altitude is substantially equal to the transmitted altitude. estimated rate then validated). In the hypothesis where several identifiers could be selected, the association module retains as identifier that cor ⁇ responding to the most unfavorable case, that is to say that leading to the lowest estimated distance and the speed of highest approximation.
• the identification code chosen is specific to the association module until the data associated with this identification code can be associated with a transmitted identifier and to the data associated with it.
• the identification code is thus either specific to the association mode if no signal has yet been received or to the identifier extracted from the received signal if such a signal has been received.
• the directive antenna makes it possible to remove ambiguities during the association by making it possible to determine a direction of emission of the signal and to check its compatibility with the angle of bearing determined in the image.
• the elevation angle can be used to determine a trajectory of the intruding aircraft in order to develop an avoidance maneuver and / or to refine the collision prediction.
• the processing unit 4 is also preferably arranged to determine the approach speed of the intruder aircraft from a dimension of the aircraft intruded in two successive images captured by the optronic device.
• the image processing module extracts from each image a solid angle formed by the surface of the aircraft intruded into each image or the pixel size of the aircraft intruded into each image.
• an estimated distance between the drone and the intruder aircraft it is possible to determine an estimated distance between the drone and the intruder aircraft (it will also be possible to use a size of the intruder aircraft obtained from information contained in the mode signal S).
• the processing unit 4 is arranged to periodically provide approximation speeds from the variation of the solid angle or the pixel size of the incoming aircraft obtained by comparing these data of two successive images.
• the approximation speeds obtained by image processing can be compared with those obtained as a function of the variation of the estimated distance calculated as a function of the signal strength. received. This makes it possible to validate or correct the results provided by the association module. It is thus possible to compare and analyze the results obtained by using only the data from the optronic device 6 and the results obtained by also using the data extracted from the signals to retain only the least noisy results.
• the processing unit 4 is also connected to an interrogator arranged to interrogate the transponders of the aircraft operating in the vicinity.
• the invention is not limited to the embodiments described but encompasses any variant within the scope of the invention as defined by the claims.
• the invention can be used with transponders operating in modes other than mode S, for example mode C or the transponder modes of military aircraft. If the signal has no identifier, information consistent with the received signal is sought to identify the corresponding track.
• the invention can also be used with the automatic dependent surveillance system ADS-B in which the intruder aircraft periodically transmits an omnidirectional signal containing in particular its position and altitude.
• the positioning data is the bearing angle of the intruder aircraft, the method thus comprising the steps of:
• the processing unit may be arranged to extract from the image other information than that cited and for example an elevation angle of the intruder aircraft.
• this angle of elevation is not used because it is considered that the intruder aircraft is heading straight for the drone to take into account the most critical situation in the navigation of the drone.
• the altitudes used may be barometric elevations and / or obtained by a satellite geolocation.

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• Engineering & Computer Science (AREA)
• Aviation & Aerospace Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Radar Systems Or Details Thereof (AREA)
• Position Fixing By Use Of Radio Waves (AREA)
• Traffic Control Systems (AREA)

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• 2014
  • 2014-05-12 FR FR1454215A patent/FR3020892B1/fr active Active
• 2015
  • 2015-04-30 CN CN201580024800.XA patent/CN106463066B/zh active Active
  • 2015-04-30 US US15/310,015 patent/US10157547B2/en active Active
  • 2015-04-30 MX MX2016014766A patent/MX360561B/es active IP Right Grant
  • 2015-04-30 WO PCT/EP2015/059603 patent/WO2015173033A1/fr active Application Filing
  • 2015-04-30 RU RU2016148537A patent/RU2661242C2/ru active
  • 2015-04-30 EP EP15720330.8A patent/EP3143608A1/fr not_active Withdrawn
• 2016
  • 2016-11-08 IL IL248823A patent/IL248823A0/en unknown

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