Air traffic monitoring system

Abstract

The present document relates to an optronic system (10) for monitoring air traffic, comprising a mast (14) of longitudinal axis (L) and at least one secondary camera (16) having a secondary angular aperture (17) and at least two static primary cameras (18, 18a, 18b, 18c, 18d) having a primary angular aperture (Pa, Pb, Pc, Pd) which is greater than the secondary angular aperture (17) of the secondary camera (16), said at least two primary cameras (18, 18a, 18b, 18c, 18d) being arranged around the longitudinal axis (L) and borne by the mast (14) and said secondary camera (17) being movably mounted on the mast (14), the system (10) further comprising means (40) for rotating the secondary camera (17), means (43) for recognizing and tracking an aircraft, and means (42) for controlling the movement means (40) for moving the secondary camera (16).

Description

Description Title: Air traffic surveillance system Technical field

[0001] This disclosure relates to the field of air traffic surveillance systems and methods, more particularly for uncontrolled aerodromes. Prior art

[0002] Controlled and uncontrolled aerodromes are two types of airport infrastructure that differ in the presence or absence of a control tower and air traffic control services. Each of these types offers distinct characteristics and procedures for pilots and flight operations.

[0003] A controlled aerodrome has a control tower where air traffic controllers work to manage aircraft movements. ATCs (air traffic controllers) ensure the safety of flight operations by providing air traffic control services, such as managing takeoffs, landings, and in-flight traffic. Pilots establish radio communication with the control tower and follow instructions issued by controllers for their movements on the aerodrome and in the surrounding controlled airspace. Controlled aerodromes also offer advanced navigation instruments, such as approach aids and instrument landing systems (ILS), which facilitate flight operations in adverse weather conditions.

[0004] In contrast, uncontrolled airfields do not have a control tower or air traffic controllers. Pilots operating at these airfields use a specific radio frequency to communicate with each other and share information about movements on the airfield. They are responsible for their own safety and air traffic management, following standard procedures and exercising increased vigilance to avoid potential conflicts with other aircraft. Uncontrolled airfields are usually equipped with visual aids such as beacons, runway identification signs, and ground markings to facilitate pilot navigation.

[0005] Uncontrolled aerodromes far outnumber controlled aerodromes, as many rural and remote areas do not require air traffic control services.

[0006] In many countries, there are a large number of uncontrolled aerodromes used primarily for general aviation, recreational flights, agricultural operations, training flights, etc. These aerodromes can be small local facilities, training aerodromes, air sports aerodromes, relief aerodromes, and many others. For example, in France, there are approximately 450 to 500 uncontrolled aerodromes.

[0007] Uncontrolled aerodromes can be classified into two categories depending on whether they include an AFIS (Aerodrome Flight Information Service) service or not.

[0008] AFIS (Aerodrome Flight Information Service) is a type of air traffic control service provided at some uncontrolled aerodromes. Unlike controlled aerodromes that have a control tower and air traffic controllers, uncontrolled aerodromes with AFIS have a flight information service.

[0009] The AFIS service is usually provided by qualified personnel called Flight Information Service Officers (FISOs). FISOs are responsible for providing information and advice to pilots operating at and around the aerodrome. Their primary role is to ensure the safety of flight operations by providing relevant information on weather conditions, local air traffic, aerodrome procedures, and other useful information to pilots.

[0010] FISOs are responsible for monitoring air traffic using visual aids, such as binoculars or electronic devices, to assist in the identification and separation of aircraft. They may also provide guidance and instructions to pilots, including ground movements, takeoffs, and landings, while coordinating aircraft activities on the airfield.

[0011] It is important to note that AFIS is not strictly air traffic control, but it does provide pilots with a source of information and support to help them make informed decisions about their flights. It aims to improve the safety of operations at uncontrolled aerodromes by providing limited but valuable assistance to pilots.

[0012] More and more controlled airfields are being transformed into uncontrolled airfields due to insufficient air traffic and / or increasing operating costs (standards to be respected, etc.).

[0013] However, flying through an uncontrolled aerodrome leads to the following difficulties: knowing the air traffic at an aerodrome, collecting the fees associated with this air traffic, knowing the state of the infrastructure (state of the runways, fire, accident, etc.) and arranging flight schedules to optimize noise around the aerodrome.

[0014] It is therefore understandable that the detection of aircraft on an uncontrolled aerodrome is important. To this end, automatic air traffic detection systems have already been proposed. They are based on: optical or radar systems from the automotive industry, with ranges of a few dozen meters, which requires the installation of equipment at each exit from an aerodrome taxiway, cooperative surveillance systems of the ADS-B (Automatic dependent surveillancebroadcast) type, but which only equip a very limited part of the aerodrome aircraft fleet (around 10 to 20%), TCAS (Traffic Alert and Collision Avoidance System) systems, but which equip a very limited part of the aerodrome aircraft fleet, since this concerns aircraft weighing more than 5,700 kg or those authorized to carry more than 19 passengers which do not constitute the majority of the aircraft fleet using uncontrolled aerodromes.

[0015] These systems are restrictive in terms of installation for the aerodrome manager, and do not cover all air traffic at the aerodrome.

[0016] Furthermore, none of the current systems allows for simple and rapid tracking of an aircraft in such a way as to provide certain information on the landing of an aircraft.

[0017] Currently, the high variability of situations on aerodromes prevents the development of a sufficiently reliable algorithm to detect an aircraft and only an aircraft. Among the elements that impact detection, we note: The movement of trees in strong winds, The movement of grass in medium winds, Cloud shadows on the ground moving, Clouds of smoke, Cars driving in the camera's field of view, The birds, which depending on their location, appear to the camera to be the size of an airplane.

[0018] This document therefore aims to propose a universal air traffic monitoring solution that is simple to implement. Summary

[0019] This document relates to an optronic system for air traffic monitoring, in particular for an uncontrolled aerodrome, comprising a mast with a longitudinal axis and at least one secondary camera having a secondary angular aperture and at least two static primary cameras having a primary angular aperture which is greater than the secondary angular aperture of the secondary camera, said at least two primary cameras being arranged around the longitudinal axis and carried by the mast and said secondary camera being mounted movably on the mast around the longitudinal axis, the system further comprising: means for rotating the secondary camera around the longitudinal axis so as to move an optical axis of the secondary camera over a predetermined angular distance to perform dynamic tracking of an aircraft in the landing or takeoff phase,means for recognizing and tracking an aircraft in a static primary angular aperture, and means for controlling the means for moving the secondary camera, these control means being connected to the means for recognizing and tracking an aircraft in a primary angular aperture.,

[0020] According to this configuration, the secondary camera having a small angular aperture is suitable for tracking an aircraft during landing or takeoff, which makes it possible to have sufficient optical resolution for identifying the aircraft's identification plate. On the contrary, the primary cameras are oriented towards the ends or ends of runways so that all the ends of the runways are located in one of the primary angular apertures. The primary camera has a larger primary angular aperture so as to encompass at least one end of a runway and may have a resolution lower than the resolution of the secondary camera. Thus, these primary cameras have a large angular aperture in order to scan a wide angular field around a runway end.

[0021] The system allows to know the presence of an aircraft in the primary angular aperture of a primary camera and also allows its tracking in said static primary aperture. The tracking which is carried out in a primary aperture is tracking in a fixed angular field. The primary camera being static, this is dynamic tracking in the static angular aperture of the primary camera, unlike the first camera which is connected to means for controlling its movement which performs tracking in the secondary angular aperture which moves around the longitudinal axis of the mast.

[0022] A static camera is a camera that is static when viewed on its own. As will be discussed later in this document, the static camera may be mounted on elements that allow it to move, rotate, etc.

[0023] In other words, the cooperation of the static camera with said elements allows the movement, rotation, etc., of said static camera.

[0024] Furthermore, the touchdown point of an aircraft, corresponding to the area generally preferred for reading the registration, depends heavily on the pilot's piloting technique so that this point varies greatly along the axis of a runway. The invention proves to be particularly advantageous for guaranteeing registration reading in all circumstances by the mobile camera rotating around the axis of the mast, i.e. in azimuthal. Depending on the shape of the wings (V-shaped for example) and the horizontal and vertical empennages of the aircraft, it is sometimes difficult, or even impossible, to read the registration completely from a single angle. The secondary camera thus allows tracking of the aircraft and reading of the registration over a predetermined angular distance stored in a database.

[0025] Finally, unlike an optronic system which would consist of a single mobile camera and which would require regularly viewing both ends of a runway, with the risk of missing an approaching aircraft during the scanning time, the proposed system makes it possible to guarantee that each end of the runway is always under the surveillance of a primary camera, the secondary camera only carrying out monitoring for the identification of the aircraft.

[0026] The primary angular apertures of said primary cameras may all be identical.

[0027] Thus, all primary cameras have the same angular aperture value, which allows for indifferent positioning of each primary camera on the mast.

[0028] Said primary cameras can be arranged on a circle centered on the longitudinal axis.

[0029] Each primary camera may be mounted on support means comprising means for moving the optical axis of the primary camera along at least one of azimuthal orientation, elevation orientation and translation relative to a radial direction with respect to the longitudinal axis.

[0030] In a particular embodiment, the means for moving the primary camera can be connected to motors arranged inside the mast.

[0031] Each of the support means may comprise a plate, one end of which is secured to a ring carried by the mast and another end of which carries the means for moving the optical axis of a primary camera.

[0032] When the mast is telescopic and comprises several tube segments mounted one inside the other, the ring can be carried by an end segment of the mast, that is to say a segment intended to form an end when it is deployed or not deployed.

[0033] Each ring may include a plurality of connectors for connecting the video and power signals of each of said primary cameras.

[0034] Thus, each primary camera is associated with a plurality of connectors, for example two connectors for video signals and one connector for power supply. The arrangement of the connectors on a ring carried by the mast makes it possible to secure the optical and power connection of the primary cameras to the mast by making a connection recovery on a static element secured to the mast. Thus, the connectors can be connected to cables extending inside the mast, which can thus be hollow. The cables are thus protected from the weather.

[0035] The mast is advantageously a telescopic mast.

[0036] In a particular embodiment, the mast comprises a plurality of tubes inserted into each other and capable of sliding relative to each other. The mast can thus comprise k tubes with a section reducing from one end to another end of the mast.

[0037] A protective wall, preferably frustoconical, may be arranged longitudinally between the secondary camera and the primary cameras, the frustoconical wall advantageously having a reduced section towards the secondary camera and a larger section towards the primary cameras.

[0038] This wall is intended to protect the primary cameras from the elements in particular. It can also help limit glare on the primary cameras.

[0039] The present document also relates to an assembly comprising at least one takeoff / landing runway for an aircraft comprising a first end and a second end and a system as described previously, in which the optical axis of a first primary camera is oriented so that its primary angular aperture includes the first end of the runway and the optical axis of a second primary camera is oriented so that its primary angular aperture includes the second end of the runway, the control means being configured so as to move the secondary camera around the longitudinal axis between a first tracking start position and a second tracking end position.

[0040] The first position corresponds to a waiting position in which the first camera waits for the aircraft to enter its angular opening. From this moment, the first camera is moved around the longitudinal axis so as to allow tracking of the aircraft, this tracking being carried out over a certain angular distance.

[0041] The optical axis of the secondary camera may be arranged such that its secondary angular aperture at least partially intercepts the primary angular aperture of the primary camera when the secondary camera is in its first position.

[0042] Positioned in this way, redundancy of the secondary and primary angular apertures is achieved, which ensures that the aircraft is tracked with the secondary camera when the aircraft leaves the angular aperture of the primary camera.

[0043] This document may also relate to a method for detecting an aircraft in the landing or take-off phase at an aerodrome, in particular an uncontrolled one, the aerodrome comprising at least one runway having at least two ends, and by means of an optronic system comprising at least at least one primary camera having a primary angular aperture oriented towards a first end of the track, the method comprising the steps: Determination of a set of possible approach or departure trajectories on said at least one runway, Determining a position of said at least one primary camera so that its primary angular aperture includes said set of possible trajectories, Determination, in the primary angular aperture, of an analysis zone shaped so as to include all of said approach or departure trajectories and preferably located above the horizon; Determination of an end of approach or end of departure region in the analysis zone; Carrying out, in said analysis zone, a detection of objects having a size compatible with that of an aircraft, Determination of the presence or absence, in the end of approach or end of departure region, of an object compatible with an aircraft, and where appropriate analysis of the path of the detected object by comparison of its current position with a history of the positions of objects detected in the analysis zone and included in the database.

[0044] The optronic system can also be of the aforementioned type.

[0045] In practice, over at least one or more days, aircraft flights are recorded in order to identify all possible trajectories. It is advisable to have at least a hundred flights to be sure of having all possible trajectories. It is understood that the set of approach or departure trajectories is a set allowing the approach or departure trajectories to be positioned in three dimensions in relation to the runway.

[0046] The aircraft approach or departure zone can thus be chosen to be less than the primary angular aperture of the second camera, which makes it possible to reduce the area analyzed in real time.

[0047] According to another characteristic, the indication that an aircraft is in the approach or departure phase can be carried out by verifying that: a) At least one object has been detected in the approach or departure zone and on at least k lm-S4i images, i varying from 1 to k, k being a natural integer greater than or equal to 1, said at least k lm-S4i images temporally preceding the lm-S4 image afor which an object has been detected in the end-of-approach or end-of-removal region, b) there are at least k lm-S4i images comprising at least one object of a size compatible with that of an aircraft and the abscissa of each of the objects is greater (or less depending on whether the object assumed to be an aircraft is arriving towards one end or the other of the runway) than the abscissa of the object detected in the end-of-approach or end-of-removal region, c) determining all the possible paths between the objects of the successive lm-S4i images, i varying from 1 to k, and leading to the object identified on the lm-S4 image a , then we validate whether a trajectory follows a straight line or not.

[0048] According to this document, the three aforementioned conditions must have been validated to be able to confirm that an aircraft is indeed in the end-of-approach or end-of-removal region. The last linear regression step makes it possible to confirm the non-chaotic aspect of the trajectory. Indeed, a chaotic trajectory would be incompatible with the trajectory of an aircraft, but could be compatible with the trajectory of a bird having a size compatible with that of an aircraft, for example due to a location closer than that of an aircraft. A natural integer p can be between 2 and k, and the indication that an aircraft is in the approach or removal phase can be achieved by additionally carrying out the following steps: calculation, for example in pixels, of the differences in abscissas Aabs and / or the differences in ordinates A ot of said at least one object between two successive images among the p images lm-S4 q, q varying from 1 to P, and determination of the sign of the Aabs and / or the O rd.

[0049] By abscissa and ordinate we mean the coordinates along the horizontal axis and the vertical axis respectively.

[0050] The horizontal axis has a direction from the end of the runway where the aircraft lands (runway entrance) to the end of the runway where the aircraft takes off (runway exit). The vertical axis has a direction from bottom to top (i.e. from the ground to the sky).

[0051] By differences in abscissas and differences in ordinates between a second image and a first image which precedes the second image (i.e. the second image follows the first image), we mean the difference between the abscissa of the second image and the abscissa of the first image and the difference between the ordinate of the second image and the ordinate of the first image respectively. The differences in abscissas and differences in ordinates can therefore be negative.

[0052] More specifically, the determination of the sign of Aabs and / or A O rd may include determining: -- in the case of an approach phase, if the Aabs are positive (i.e. > 0) and / or the A O rd are negative (i.e. < 0); and / or -- in the case of a distancing phase, if the Aabs are positive (i.e. > 0) and / or the A O rd are positive (i.e. > 0).

[0053] In particular, in the case of an approach phase, if the Aabs are positive (i.e. > 0) and / or the A O rd are negative (i.e. < 0), it is possible to deduce where appropriate that said at least one object is an aircraft in the approach phase.

[0054] In the case of a distancing phase, if the Aabs are positive (i.e. > 0) and / or the A O rd are positive (i.e. > 0), it is possible to deduce where appropriate that said at least one object is an aircraft in the moving away phase.

[0055] In this way, the determination of the indication that an aircraft is in the approach or departure phase is reinforced by filtering out objects making horizontal and / or vertical round trips. For example, this may be the case for objects, such as birds, which have differences in abscissa and ordinate of variable or inconsistent signs with respect to an aircraft landing or takeoff.

[0056] In one aspect, it is possible to determine only the sign of the Aabs.

[0057] Indication that an aircraft is approaching or departing can be achieved by additionally performing the following step: Determination that an aircraft is in the approach or departure phase by comparing the Aabs and / or Aords with a predetermined minimum and / or maximum value from a history of abscissa differences and ordinate differences included in the database.

[0058] In other words, we ensure that the previously calculated Aabs and / or Aord are included in a range including as a lower limit the predetermined minimum value and / or as an upper limit the predetermined maximum value.

[0059] According to one aspect, if the Aabs and / or Aord are included in said range, it is possible to deduce where appropriate that said at least one object is an aircraft in the approach or departure phase.

[0060] In this way, consistency between the abscissa differences and the previously calculated ordinate differences is guaranteed, and the determination of whether an aircraft is approaching or departing is further reinforced.

[0061] It should be understood that the history of abscissa differences and ordinate differences may come from at least a hundred aircraft flights, preferably several hundred.

[0062] Indication that an aircraft is approaching or departing can be achieved by additionally performing the following steps: Calculation of the standard deviation of the abscissa differences o a bs and / or the standard deviation of the ordinate differences Gord, and Determining whether an aircraft is approaching or departing by comparing o abs and / or Gord with an abscissa threshold standard deviation Oseuil_abs and / or an ordinate threshold standard deviation Oseuil_ord respectively, Gseuii_abs and Gseuii_ord being predetermined from the history of abscissa differences and ordinate differences.

[0063] oseuii_ab and Gseuii_ord measure the dispersion of values ​​around their respective means. By making this comparison, we can assess how much Aabs and Aord differ from the mean in terms of variability.

[0064] More particularly, if at least one of the Aabs and / or Aords previously calculated is less than or equal to Oseuil_abs and / or Oseuil_ord respectively, then it is possible to deduce where appropriate that said at least one object is an aircraft in the approach phase.

[0065] The optronic system may comprise at least one second primary camera, a primary angular aperture of which is oriented towards a second end of the runway, the method comprising: identifying possible runway exit trajectories of an aircraft at the second end of the runway; classifying said possible trajectories into three possible behaviors, a first behavior corresponding to an actual landing, a second behavior corresponding to a runway touchdown without landing and the third behavior corresponding to an overflight of the runway at low altitude, Determining a position of the second primary camera so that its primary angular aperture includes all possible track exit trajectories, Determination, in the primary angular aperture of the second primary camera, of three zones, a first end-of-runway zone corresponding to the first behavior, a second end-of-runway zone corresponding to the second behavior and a third end-of-runway zone corresponding to the third behavior.

[0066] From an aircraft's approach or departure path, it is difficult to determine whether the aircraft will actually land, just touch the runway or just fly over the runway at low altitude (in the case of a landing), or actually take off. Since it is not possible to discriminate between these scenarios from the approach or departure path alone, an analysis must be carried out using a second primary camera located at the second end of the runway.

[0067] Obviously, we understand that the first primary camera can play the role of the second primary camera depending on the direction of aircraft landings or takeoffs.

[0068] A runway exit trajectory is here an exit trajectory from the second end of the runway observation zone.

[0069] The process may also include: A continuous recording of the primary camera's angular aperture, For a given image at a given time t: o take the average of x images temporally preceding the given image and obtain an averaged image, o Subtract the given image from the averaged image.

[0070] The average of the previous x images is performed pixel by pixel. The number x of images used for averaging is important and will be determined by successive iterations.

[0071] Preferably, a dilation step will be applied to the given image.

[0072] This dilation step allows the contours to be closed. Preferably, objects with a surface area greater than a predetermined size are eliminated.

[0073] The position of the primary camera may be determined such that its primary angular aperture includes an intersection of said at least one runway with a taxiway.

[0074] A taxiway is an aircraft access route to the takeoff / landing runway from an aircraft stopping area. According to this document, the primary angular aperture of a primary camera includes both an end of the runway and said junction area, which makes it possible to identify that an aircraft is entering or leaving the runway.

[0075] The method may include determining an intersection region within the primary angular aperture of the primary camera, wherein the intersection region encompasses the intersection of the at least one runway with the taxiway.

[0076] The analysis zone may comprise an approach or departure zone delimited below by a first low line arranged above the runway and above by a second high line arranged above the first line, the approach or departure zone being connected to the end of approach or end of departure region.

[0077] The first low line may have an inclination of a non-zero angle a relative to the axis of said at least one track, a may be greater than or equal to 3°.

[0078] The minimum angle should be chosen as the minimum value given by an administration competent in aeronautical legislation for the aerodrome in question. In France, the minimum value is 3° with a possible deviation of 0.5°.

[0079] This inclination, which is at least 3° higher than the runway axis, makes it possible to remove part of the scenery that could lead to so-called false positive detections of an aircraft.

[0080] The second high line may have an inclination of an angle P greater than the angle a, the angle P being determined as corresponding to the maximum possible angle of arrival of an aircraft on said at least one runway.

[0081] In practice, a value of 9° corresponds to an approach or departure standard.

[0082] The optronic system used with the method described above may comprise a secondary camera which is mobile and rotates around a vertical axis so that its optical axis can follow a moving aircraft, the method comprising a subsequent step of following an aircraft after indicating the presence of an aircraft in the end-of-approach or end-of-removal region. Brief description of the drawings

[0083] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which:

[0084] [Fig. 1] illustrates an optronic system according to this document in an undeployed position in Fig. 1A and in a deployed and ready-to-use position in Fig. 1B;

[0085] [Fig. 2] is a schematic perspective view of an optronic system according to the present document in an undeployed position, the system being shown without the support elements visible in Fig. 1;

[0086] [Fig. 3] is a schematic perspective view of a portion of the mast supporting a plurality of primary cameras and in a bottom-up orientation

[0087] [Fig. 4] is an enlarged view of the means of moving each primary camera in order to achieve static positioning of the primary camera in a desired position

[0088] [Fig. 5] is a schematic view of the system, similar to Figure 3, and viewed in a top-down orientation;

[0089] [Fig. 6] represents a flowchart of interaction of the means of controlling the movement of the secondary camera;

[0090] [Fig. 7] is a schematic view illustrating several existing takeoff / landing runway configurations at an uncontrolled aerodrome;

[0091] [Fig. 8] is a schematic view illustrating a taxiway in junction with a takeoff / landing runway at an uncontrolled aerodrome;

[0092] [Fig. 9] comprises a part A which represents an image of an area of ​​space observed through an angular aperture of a first primary camera oriented towards a first end of a track and part B represents an image of an area of ​​space observed through an angular aperture of a second primary camera oriented towards a second end of the track;

[0093] [Fig. 10] is an image of another area of ​​space observed through an angular aperture of a primary camera oriented towards another end of a track;

[0094] [Fig. 11] is an enlarged image of part of Figure 10;

[0095] [Fig. 12] is an illustration of the steps for detecting motion in the angular aperture of a primary camera;

[0096] [Fig. 13] is an illustration of several attempts to detect motion in a given image acquired by the primary camera;

[0097] [Fig. 14] is a flowchart of the steps for detecting objects and indicating the presence of an aircraft in an end-of-approach region;

[0098] [Fig. 15] illustrates different possible paths obtained from images stored in a database;

[0099] [Fig. 16] illustrates a possible landing path obtained from images stored in a database. Description of the embodiments

[0100] The following description presents a system 10 according to the invention and a method intended more particularly for the use of said system. The method can be implemented during an approach / landing phase or during a takeoff phase. This description is carried out in relation to the landing phase, but also applies to the takeoff phase.

[0101] Reference is now made to Figure 1 which represents a system 10 according to the present document. The system 10 can be installed on a flat support 12 such as a concrete slab. It comprises a mast 14 carrying a secondary camera 16 movable in rotation around the longitudinal axis and at least two primary cameras 18 (better visible in Figure 2) which are fixed. By rotating mobile camera and fixed camera, it is meant that in operation the camera is able to move and by static or fixed camera, it is meant that the camera is fixed in operation, that is to say when the system is used. Obviously, for adjusting the positioning of the primary cameras 18, these can be connected to appropriate movement means as will be seen in the following.

[0102] The mast 14 may advantageously be telescopic as illustrated in FIGS. 1A and 1B and may thus comprise a plurality of tubular segments 15 arranged one inside the other. The system 10 is here surrounded by a protective enclosure 20 intended to prevent damage by unauthorized persons (intrusions) or due to impacts by aircraft (wingtip impacts). The mast 14 extends along a longitudinal axis L which is arranged in a vertical position. It comprises a lower end or first end 14a and an upper end or second end 14b. The mast 14 is held in a vertical position by a plurality of support arms 15 articulated in rotation between a support position and a waiting position.

[0103] Each camera 16, 18 comprises its own angular aperture. The secondary camera 16 comprises a secondary angular aperture 17. The system 10 comprises at least two primary cameras 18a, 18b. Thus, each primary camera is referenced 18 followed by a reference a, b, c, d... designating respectively the rank 1 for first, 2 for second ... of the primary camera. The first primary camera is therefore denoted 18a, the second primary camera is denoted 18b, the third primary camera is denoted 18c, etc... Each angular aperture is denoted 18x where x is a letter designating the primary camera 18x. Each primary camera 18x includes a primary angular aperture Px where x is a letter designating the angular aperture of the camera 18x. Thus, the first primary camera 18a has a primary aperture Pa, the second primary camera 18b has a primary aperture Pb, the third primary camera 18c has a primary aperture Pc, the fourth primary camera 18d has a primary aperture Pd,... As can be seen in Figure 7, the primary angular aperture Pa, Pb, Pc, Pd of each of the primary cameras 18a, 18b, 18c, 18d is greater than the secondary angular aperture 17.

[0104] The optronic system is suitable for installation on any type of uncontrolled aerodrome. It is thus suitable for installation on uncontrolled aerodromes having a configuration of runways V1, V2 as shown in FIGS. 7A, 7B, 7C, 7D. It will be easily understood, in light of the description, that the invention is applicable to any type of aerodrome comprising one or more runways. The 2D configuration of the runways, i.e. the number of runways as well as the two-dimensional arrangement of the axes of the runways relative to each other determines the number of primary cameras 18 required and the positioning of the primary cameras 18. In practice, when the aerodrome comprises more than two runways, it will be preferable to use more than one optronic system.In such a situation, an optronic system will advantageously comprise four primary cameras which are used to monitor the ends of two runways and another optronic device will be used to monitor the ends of the runways beyond said two runways.

[0105] In the configuration illustrated in the figures, the primary cameras 18 are positioned around the longitudinal axis L and are preferably arranged on a circle having a center located on the longitudinal axis L of the mast 14. In other words, the circle intercepts each primary camera 18. However, this does not mean that each primary camera 18 is positioned in space in the same way relative to this circle.

[0106] The secondary camera 16 is carried by the second end 14b of the mast 14. In one embodiment, the optical axis of the camera is intercepted by the longitudinal axis of the mast 14. It can be seen that a protective wall 20 can be interposed between the primary cameras 18 and the secondary camera 16 (Figures 2 and 3). In Figure 5, the protective wall 20 has been removed to facilitate viewing of the parts located beneath it. The protective wall 20 can have a frustoconical shape, the section of the wall 20 preferably having a section reducing towards the secondary camera 16.

[0107] Each primary camera 18 may be mounted on support means comprising means for moving the optical axis of the primary camera along at least one of the azimuthal orientation, the elevation orientation and a translation relative to a radial direction with respect to the longitudinal axis L.

[0108] The moving means may be motors illustrated at 22 and which may be arranged inside the mast 14 so as to protect them.

[0109] The means for moving each primary camera 18 are carried by a support 24 comprising a plate having a substantially triangular shape. One end of the plate 24 is secured to a ring 26 carried by the mast and another end carries the means for moving the optical axis of a primary camera 18 (figure 5). The means for moving a primary camera 18 comprise means of elevation displacement, azimuthal displacement means and translational displacement means relative to the longitudinal axis L (figure 4).

[0110] The elevation movement means comprise a yoke 28 secured to the primary camera 18 and an arm 30 articulated in rotation on the yoke 28. The articulation is produced along a horizontal axis 32, that is to say an axis perpendicular to the longitudinal axis and positioned so as to allow adjustment of the orientation of the axis of the primary camera 18 relative to a horizontal plane.

[0111] The azimuthal displacement means comprise the arm 30 which is mounted in rotation on a member 32 around a vertical axis 34 parallel to the longitudinal axis L.

[0112] The translational movement means comprise the member 32 and a rail 38, the member 32 being able to move along an axis 36. The rail may be a rail of the Picattiny® rail type.

[0113] The means of movement are connected to motors arranged inside the mast 14.

[0114] As can be seen in Figure 5, the ring 26 comprises connectors, preferably a plurality of connector triplets C1, C2, C3, each triplet being associated with a primary camera 18. Two connectors C1, C2 are provided for the transfer of video signals and a connector C3 is provided for the electrical power supply of a primary camera 18. These connectors make it possible to connect the video and electrical cables of a primary camera 18 to a static support of the mast 14.

[0115] According to the present disclosure, the system 10 may comprise means 40 for moving, in particular in rotation, the secondary camera 16 around the longitudinal axis L so as to move an optical axis of the secondary camera 16 over a predetermined angular distance D to perform dynamic tracking of an aircraft in the landing or takeoff phase, and means 42 for piloting the means 40 for moving. The piloting means 42 are connected to means 43 for recognizing and tracking an aircraft in a primary opening Px.Thus, the piloting means 42 in communication / link with the recognition and tracking means 43 are informed about the positioning of an aircraft in a static primary angular opening Px and make it possible to actuate the movement means 42 to carry out movement tracking of the aircraft in the secondary angular opening 17 - moving in rotation with the secondary camera 16 - to allow identification of the aircraft. The movement means 40 of the secondary camera 16 may also comprise means for moving the optical axis of the secondary camera 16 in elevation.

[0116] The piloting means 42 therefore receive positive detection information from an aircraft. This detection is carried out continuously from the images acquired in real time by each of the primary cameras 18. The analysis of the images from the primary cameras 18 is carried out in time and the detection can therefore be carried out in real time. Figure 6 illustrates a flowchart of interaction between the secondary camera 16 connected to the movement means 40 which are controlled by the piloting means 42 which receive positive detection information from an aircraft detected in a primary aperture Px of a primary camera 18. Each second camera is connected to the recognition and tracking means 43 of an aircraft in the primary angular aperture of a primary camera.

[0117] The means of identification of an aircraft are means of identifying the aircraft, that is to say means of recognizing the characters of a registration plate located on the aircraft. recognition and tracking means 43 designate means for identifying the presence of an aircraft in the visual field of a primary camera 16 and tracking it in the angular field Px.

[0118] The secondary camera 16 may be a SONY®- 4K 200-600mm, 12° - 4° SCMOS camera having a continuous x3 optical zoom extending between 200 to 600 mm. It may have a low light level 3 capability (ISO > 400,000). Each primary camera 18 may be a SONY®- 4K FCB-ER8550, 4.4- 88 mm, 60° - 3.5° CMOS camera and having a continuous x20 optical zoom between 4.4 and 88 mm.

[0119] We now refer to Figure 7 which represents different track configurations. In Figure 7A, the configuration is such that two tracks V1, V2 are parallel to each other. In Figure 7B, the configuration is such that two tracks V1, V2 form a non-zero angle with respect to each other and do not intercept each other, the tracks V1, V2 forming an angle less than 90° and in this case approximately 40°. In Figure 7C, the configuration is such that two tracks V1, V2 intercept each other with an angle less than 90°, in this case of the order of 30°. In Figure 7D, the tracks V1, V2 are perpendicular to each other and intercept each other and in this case substantially in their middle.

[0120] In the different configurations illustrated, the primary angular apertures Px of the primary cameras 18 are all identical. They could still be different. Each runway V1, V2 comprises a first end E1 and a second end E2. An aircraft can take off and land from one end E1 or E2 of each runway, depending on the wind direction.

[0121] For each 2D configuration of the runways of an aerodrome (figures 7A, 7B, 7C, 7D), it is necessary to determine the number of primary cameras 18 required and the positioning of the primary cameras 18. In each configuration, each runway is arranged or covered by the angular opening of a primary camera 18. A given primary camera can thus cover several ends E1, E2 of runways V1, V2.

[0122] In the configuration of Figure 7A, the first primary angular aperture Pa of a first primary camera 18a covers both ends E1 of the two tracks V1, V2 while the second primary angular aperture Pb of the second primary camera 18b covers both ends E2 of the two tracks V1, V2. Thus, in a parallel track configuration, only two primary cameras 18 are required.

[0123] In the configuration of Figure 7B, it is observed that it is necessary to have three primary cameras 18, the first primary angular aperture Pa of a first primary camera 18a covers the two ends E2 of the two tracks V1, V2 while the second primary angular aperture Pb of the second primary camera 18b covers one end E1 of the track V1 and the third primary angular aperture Pc of the third primary camera 18c covers one end E1 of the track V2.

[0124] In the configuration of Figure 7C, it is observed that two primary cameras 18 are required. The first primary angular aperture Pa of a first primary camera 18a covers the two ends E1 of the two tracks V1, V2 while the second primary angular aperture Pb of the second primary camera 18b covers the two ends E2 of the two tracks V1, V2.

[0125] In the configuration of Figure 7D, it is observed that it is necessary to have four primary cameras 18. In this configuration, each primary angular aperture of a primary camera covers a single end E1, E2 of a track V1, V2.

[0126] In the configurations shown in Figure 7, a secondary camera 16 is used to track an aircraft from the end E1, E2 where it was detected. For example, when the aircraft is detected in the landing / takeoff phase in one of the images from a primary camera 18, the secondary camera 16 tracks the aircraft during landing / takeoff on the relevant runway V1, V2.

[0127] Each runway V1, V2 is associated with a primary camera 18 for detecting an aircraft in the takeoff / landing phase at each of its ends E1, E2. Each position of a primary angular aperture Px of a primary camera 18 is associated with a first tracking start position for the takeoff / landing phase for the secondary camera 16. This first tracking start position is such that the secondary angular aperture 17 of the secondary camera 16 intercepts at least partially the primary angular aperture of the primary camera 18 achieving a positive detection. In practice, there are as many first positions as there are primary cameras 18. Each secondary camera is associated with a second tracking end position which can be fixed for a runway configuration.It can also be a function of a positive identification of an aircraft, thus leading to stopping the tracking of the aircraft by the secondary camera 16, which can for example take a waiting position in the first tracking position at the level of a runway V1, V2.

[0128] In this document, a system comprising a single secondary camera is presented. However, it is understood that the present disclosure, in all its characteristics, also applies to a system comprising at least one secondary camera and therefore capable of comprising a second secondary camera. Such an additional secondary camera could be used simultaneously with the first secondary camera to position itself in a first tracking or waiting position while the first camera tracks the trajectory of an aircraft in the process of landing. This configuration would be particularly advantageous when the aerodrome comprises a larger number of runways, for example more than two, which would make it possible to manage greater air traffic with the system.

[0129] Preferably, the primary angular aperture Px, Pa, Pb of each primary camera is configured to comprise a zone 46 for junction of a taxiway 44 to a runway V1. Thus, the primary angular aperture Px of a primary camera 18 comprises both an end E1, E2 of the runway V1 and said junction zone 46, which makes it possible to identify that an aircraft is entering or leaving the runway V1 (FIG. 8).

[0130] The positioning of the optronic system around the runways is carried out according to the maximum range of the secondary camera 16. The reading being done on the central third of each runway, the optronic system will then be placed on the intersection of two discs of radius equal to the maximum range of the secondary camera 16, in the case of a two-runway configuration. The two-runway configuration is the most common. Other parameters can be taken into account such as the relief (because the runways are not always flat), masks (buildings, trees, etc.) which reduce the possibilities within this intersection.

[0131] The method described below in the figures is intended to be implemented using an optronic system for monitoring air traffic, in particular for an uncontrolled aerodrome, comprising at least one secondary camera 16 having a secondary angular aperture 17 and at least two static primary cameras 18 having a primary angular aperture 18x which is greater than the secondary angular aperture 17 of the secondary camera 16, said at least two primary cameras being arranged around the same longitudinal axis on which said secondary camera is mounted to be movable in rotation. At least two primary cameras 18 are necessary to confirm the trajectory of an aircraft. The optronic system may comprise all or part of the characteristics of the optronic system described with reference to figures 1 to 8. However, only one can be used if one only wishes to determine the behavior of an aircraft without having confirmation of its status (it landed, touched down and departed or it flew over the airfield at low altitude) as will appear below.

[0132] We now refer to figure 9 which comprises a part A which represents an image 100 of a zone of space observed through a primary angular aperture of a first primary camera oriented towards a first end of a runway V1 and which can be described as a primary camera for the approach phase and part B represents an image 102 of a zone of space observed through an angular aperture of a second primary camera oriented towards a second end of the runway V1 and which can be described as a primary runway exit camera.

[0133] The image of Figure 9A includes several areas that are intended to serve in providing an indication of an aircraft approaching runway V1. Image 102 of Figure 9B includes several areas that are intended to serve in confirming the status of the aircraft that has entered the approach phase in the image of Figure 9A.

[0134] As can be seen, the first primary camera is oriented such that its primary angular aperture includes a first end of the track V1. The second primary camera is oriented such that its primary angular aperture includes a second end of the track Figure 9B.

[0135] In the image of Figure 9A, we observe the presence of a rectangle 104 whose dimension is smaller than the primary angular aperture of the first camera. This rectangle 104 therefore corresponds to an analysis zone, that is to say to an area in which the image processing will be carried out to detect the presence of objects related to an aircraft.

[0136] This analysis zone 104 corresponding to a reduced part of the primary angular aperture makes it possible to make digital processing compatible with a real-time analysis objective. This rectangle 104 comprises an approach zone 106 extending by an end-of-approach region 108. The approach zone has the shape of a corridor delimited below by a first low line arranged 106a above the runway and above by a second high line 106b arranged above the first line.

[0137] In order to determine the positioning of the first primary camera and more practically its azimuthal orientation, the method comprises a step of determining a set of possible approach trajectories on the runway (not visible). After this step, the position of the primary camera is determined so that its primary angular aperture includes said set of possible trajectories. In practice, the angular aperture of each primary camera is determined so as to also include a junction zone 107a of a taxiway 107 with the runway so as to be able to control the runway entries and exits corresponding to an upcoming takeoff and a completed landing. The taxiway comprises a zone 118 formed on a taxiway connected to the runway. This zone will be better described in relation to FIG. 11.

[0138] The analysis zone 104 is positioned so as to be located above the horizon, preferably grazing, and to include all of said approach trajectories to avoid including objects moving on the ground such as trees which undergo regular movements.

[0139] Thus, each approach zone 106 is associated with an end of approach region 108 which is located in the approach zone 106. This end of approach region 108 corresponds to the zone in which the detection of an object having a size compatible with that of an aircraft, triggers the implementation of a confirmation step that the identified flying object corresponds to an aircraft. Prior to the implementation of the confirmation step, flying objects compatible with an aircraft size are tracked in real time in the approach zone. Real-time tracking will be explained below with reference to Figures 12 to 14.

[0140] The method according to the present document preferably also comprises the steps of: Identification of possible runway exit trajectories for an aircraft at the second end of the runway; these runway exit trajectories correspond to all possible trajectories after the aircraft has passed a first end of the runway, passing a middle part of said runway. It is understood that there is no bijection between an approach trajectory and a given behavior of the aircraft.In other words, an aircraft having a given approach trajectory may well correspond to one of the three possibilities of runway departure trajectories mentioned above, namely the aircraft landed, the aircraft touched down and took off again and the aircraft flew over the runway at low altitude; classification of said possible trajectories into three possible behaviors, a first behavior corresponding to an actual landing, a second behavior corresponding to a runway touchdown without landing and the third behavior corresponding to an overflight of the runway at low altitude. Determining a position of the second primary camera so that its primary angular aperture includes all possible track exit trajectories, Determination, in the primary angular aperture of the second camera, of three zones, a first zone 110 at the end of the runway corresponding to the first behavior, a second 112 at the end of the runway corresponding to the second behavior and a third zone 114 at the end of the runway corresponding to the third behavior (figure 9B).

[0141] We observe the presence of a large zone 116 encompassing said three zones 110, 112, 114, this zone corresponds to that on which the real-time image processing analysis is carried out (see figures 12 to 14).

[0142] Thus, for each primary camera, there is a first set of approach zones and region for the approach phase and a second set of zones for confirmation of the aircraft status after entering the approach phase. This is necessary since each runway end can be used for takeoff and landing depending on the prevailing wind direction relative to the runway. The angular aperture of a primary camera must be such that the primary camera must be able to function as a primary camera for detecting an approach or as a primary camera for confirming the status of an aircraft.

[0143] Figure 10 illustrates another runway configuration which includes the same areas as those described in Figure 9A. However, it is understood that the shape of each of the areas is different since it is each time a function of the three-dimensional configuration of the runways of the aerodrome concerned.

[0144] Figure 11 illustrates a zone 118 formed on a taxiway connected to the runway. This zone 118 can be placed at the intersection of the taxiway and the runway or be positioned on the taxiway as is the case here. It can be seen that this zone comprises two longitudinal end regions 120a, 120b making it possible to determine the passage of an aircraft in one direction or the other. Depending on whether the aircraft passes through zone 120a or zone 120b first and then passes through the other zone, it is understood that it is possible to detect the direction of movement of the aircraft and then to check that it is moving in the correct direction as prescribed by the rules in force.

[0145] For each image obtained by either of the primary cameras, the following processing is carried out. In practice, the method for detecting an aircraft is implemented from the images of all the primary cameras 18. In this way, landing detections are carried out regardless of the landing direction, which is particularly true when the wind is light where the choice of landing direction belongs to the pilot. The primary camera 18 first detects an aircraft in the approach phase, then giving the indication to the secondary camera 16 of where it must position itself.

[0146] First, each image acquired by a primary camera is processed by an attenuation filter S1, such as a Gaussian blur, which makes it possible to standardize the image. This first step makes it possible to eliminate small objects from the image, which are therefore considered as noise. However, care must be taken to ensure that the attenuation filter applied is sufficiently low so as not to affect the aircraft detection resolution. For this, an empirical adjustment is possible on the images acquired by each primary camera in its desired position relative to one end of the runway.

[0147] In a step S2, for a given image 121 at a given time t: take the average of x images 119 temporally preceding the given image and obtain an averaged image 123 Subtract the given image from the averaged image and get a resulting image 125.

[0148] The resulting image thus includes only the parts that have undergone a displacement compared to the average of the previous images 123 (figure 12). Only the parts of the image greater than a threshold value are retained. These parts therefore correspond to parts that have moved. It is understood that the greater the number x of images taken into account, the more the resulting image will include areas greater than the threshold value. This principle is illustrated in figure 13 which shows three cases A, B and C each comprising two images, a first image 122 corresponding to the resulting image and a second image 124 corresponding to the resulting image after application of the threshold. In case A, the number of images x taken into account is 10, in case B, x is equal to 100 and in case C x is equal to 1000.

[0149] Each black and white output image undergoes a contour closing step S3 which can advantageously be carried out by contour dilation. This mathematical function is well known to those skilled in the art and will not be described in further detail. The dilation must be carried out sufficiently to avoid increasing the size of the object too significantly. An iteration may be carried out.

[0150] In a step S4, objects having a size incompatible with an aircraft are eliminated. It is understood that the size criterion does not make it possible to distinguish a bird caught in the field of a primary camera at a distance such that its size becomes compatible with the size of an aircraft located at a greater distance from the primary camera.

[0151] The processing carried out through steps S1 to S4 could be carried out on all the images acquired by the primary camera. However, this would lead to the storage of a large amount of data. To this end, steps S1 to S4 are carried out on one image out of k, where k can take a value of 3 for example. The lm-S4 images obtained at the end of step S4 are stored in a database and kept to perform step S5. Obviously, it is not necessary to keep all the lm-S4 images. In practice, we store N lm-S4 images, the choice of N being made to be able to keep enough history. Thus, we can keep a number of lm-S4 images of at least 4 when the primary camera has an acquisition rate of 25 images per second.

[0152] In a step S5, an object detection is carried out in the approach region of the image lm-S4. Thus, each processing S1-S4 is associated with an end processing consisting of verifying the presence or absence of an object compatible with an aircraft in the approach zone 108.

[0153] In the event of a positive detection of an object in approach region 108, it must be determined whether or not the detected object is an aircraft.

[0154] For this purpose, in a step S6, an indication is provided that an aircraft is in the approach phase. This step S6 makes it possible to distinguish between aircraft-type objects and other objects. Verification of the following conditions makes it possible to ensure that an aircraft is indeed in the approach phase for landing: a) At least one object has been identified in an approach region of the last image lm-S4a obtained, b) At least one object has been detected in the approach zone and on at least k images lm-S4i (i varying from 1 to k) temporally preceding the image lm-S4a for which an object was detected in the end-of-approach region, k being less than or equal to N. k is a natural integer greater than or equal to 1 and may be equal to 3.c) there are at least k lm-S4i images comprising at least one object of a size compatible with that of an aircraft and the abscissa of each of the objects is greater (or less depending on whether the object assumed to be an aircraft arrives towards one end or the other of the runway V1) than the abscissa of the object detected in the end-of-approach region, where this condition makes it possible to ensure that the object follows a continuous progression from left to right or from right to left. The origin of the abscissa is determined at one end of the runway. d) determining all the possible paths between the objects of the successive lm-S4i images (i varying from 1 to k) and leading to the object identified on the lm-S4 image. a , then we determine whether the trajectory follows a straight line or not. This last step can be carried out by determining a correlation coefficient r 2 which should preferably be greater than 0.9.

[0155] Figure 15 illustrates the objects detected on the lm-S4i images and the different possible paths. It can be seen that steps a) to c) are verified and step d is only verified for path 128, paths 132 not being sufficiently linear. Figure 15 also illustrates the direction of approach of the aircraft with arrow 134.

[0156] Reference is now made to Figure 16 which illustrates a possible landing path from lm-S4 images q , with q varying from 1 to p, and p a natural number between 2 and k.

[0157] In this particular example: p is equal to 5, and q therefore varies from 1 to 5. The abscissa axis Xabs has a direction going from left to right along the plane of the sheet. The abscissa axis Y or d has a direction going from bottom to top according to the plane of the sheet.

[0158] Differences in abscissas Aabs and ordinates Aord are measured between two successive images among the 5 lm-S4 images q : Aabs 1-2 corresponds to the difference in abscissa between lm-S42 and lm-S4i, Aord 1-2 corresponds to the difference in ordinate between lm-S42 and lm-S4i; Aabs 2-3 corresponds to the difference in abscissa between lm-S43 and lm-S42, Aord 2-3 corresponds to the difference in ordinate between lm-S43 and lm-S42; Aabs 3-4 corresponds to the difference in abscissa between lm-S44 and lm-S43, Aord 3-4 corresponds to the difference in ordinate between lm-S44 and lm-S43; and Aabs 4-5 corresponds to the difference in abscissa between lm-S45 and lm-S44, A or d 4-5 corresponds to the difference in ordinate between lm-S45 and lm-S44.

[0159] The indication that an aircraft is in the approach phase is achieved by checking that the Aabs (i.e. Aabs i-, Aabs 2-3, Aabs 3-4 and Aabs 4-5) are positive, and by checking that the Aords (i.e. Aord i-, Aord 2-3, Aord 3-4 and Aord 4-5) are negative, which is the case in the illustrated trajectory.

[0160] It is also possible to verify that the object of the lm-S4 images q is indeed an aircraft in the landing phase by further verifying that the Aabs are between a minimum value Aabs min and a maximum value Aabs max. In other words, it is possible to verify that Aabs 1-, Aabs 2-3, Aabs 3-4 and Aabs 4-5 are included in a range having the limits Aabs min and Aabs max.

[0161] Similarly, it is also possible to check that the Aords are between a minimum value Aord min and a maximum value Aord max.

[0162] An additional determination / verification criterion is the use of standard deviations.

[0163] In this particular example, we calculate the standard deviations of the abscissa differences o a bs and standard deviations of the differences of the Gord ordinates.

[0164] Then, the determination that an aircraft is in the approach phase is made by comparing o a bs and o O rd with standard deviations thresholds of abscissa Oseuil_abs and ordinate Oseuil_ord.

[0165] More specifically, we check that Oabs — Oseuil_abs , and that Oord — Oseuil_ord.

Claims

Claims

1. Optronic system (10) for monitoring air traffic, in particular for an uncontrolled aerodrome, comprising a mast (14) with a longitudinal axis (L) and at least one secondary camera (16) having a secondary angular aperture (17) and at least two static primary cameras (18, 18a, 18b, 18c, 18d) having a primary angular aperture (Pa, Pb, Pc, Pd) which is greater than the secondary angular aperture (17) of the secondary camera (16), said at least two primary cameras (18, 18a, 18b, 18c, 18d) being arranged around the longitudinal axis (L) and carried by the mast (14) and said secondary camera (16) being mounted movably on the mast (14) around the longitudinal axis (L),the system (10) further comprising: means for rotating movement (40) of the secondary camera (16) around the longitudinal axis (L) so as to move an optical axis of the secondary camera (16) over a predetermined angular distance (D) to perform dynamic tracking of an aircraft in the landing or takeoff phase, means for recognizing and tracking (43) an aircraft in a static primary angular aperture (Pa, Pb, Pc, Pd), and means for piloting (42) the means for moving (40) the secondary camera (16), these piloting means (42) being connected to the means for recognizing and tracking (43) an aircraft in a primary angular aperture (Pa, Pb, Pc, Pd).,

2. System (10) according to one of the preceding claims, wherein the primary angular apertures (Pa, Pb, Pc, Pd) of said primary cameras (18, 18a, 18b, 18c, 18d) are all identical.

3. System (10) according to one of the preceding claims, wherein said primary cameras (18, 18a, 18b, 18c, 18d) are arranged on a circle centered on the longitudinal axis (L).

4. System (10) according to one of the preceding claims, in which each primary camera (18, 18a, 18b, 18c, 18d) is mounted on support means (24) comprising means for moving the optical axis of the primary camera along at least one of the azimuthal orientation, the elevation orientation and a translation relative to a radial direction with respect to the longitudinal axis (L).

5. System (10) according to claim 4, in which each of the support means (24) comprises a plate (24) one end of which is secured to a ring (26) carried by the mast (14) and another end of which carries the means (22) for moving the optical axis of a primary camera (18).

6. System (10) according to the preceding claim, wherein each ring (26) comprises a plurality of connectors (C1, C2, C3) for connecting the video and power signals of each of said primary cameras (18, 18a, 18b, 18c, 18d).

7. System (10) according to one of the preceding claims, in which the mast (14) is a telescopic mast (14).

8. System (10) according to one of the preceding claims, in which a protective wall (20), preferably frustoconical, is arranged longitudinally between the secondary camera (16) and the primary cameras (18, 18a, 18b, 18c, 18d), the frustoconical wall (20) advantageously having a reduced section towards the secondary camera (16) and a larger section towards the primary cameras.

9. Assembly comprising at least one runway (V1) for takeoff / landing of an aircraft comprising a first end and a second end and a system (10) according to one of the preceding claims, in which the optical axis of a first primary camera (18a) is oriented so that its primary angular aperture (Pa) comprises the first end of the runway (V1) and the optical axis of a second primary camera (18b) is oriented so that its primary angular aperture (Pb) comprises the second end of the runway (V1), the control means (42) being configured so as to move the secondary camera (16) around the longitudinal axis (L) between a first tracking start position and a second tracking end position.

10. Assembly according to the preceding claim, in which the optical axis of the secondary camera (16) is arranged so that its secondary angular aperture (17) at least partially intercepts the primary angular aperture (Pa, Pb, Pc, Pd) of the primary camera when the secondary camera (16) is in its first position.

Images