Method for locating a vertical landing aircraft relative to a runway, method and associated devices

Abstract

Method for locating a vertical landing aircraft relative to a runway, method and associated devices. The present invention relates to a method for locating an aircraft (2) relative to a vertical landing runway (4) comprising at least one reflective element (20A, 20B, 22A, 22B) for a radio signal, the method comprising the following steps: - transmission of a radio signal from the aircraft (2) to the runway (4), - reception of a signal reflected by the runway (4) in response to the signal, - extraction of a pattern from the received reflected signal, each pattern being the evolution over time of the radio signal reflected by a reflective element (20A, 20B, 22A, 22B), - calculation of a vertical distance ( ) from the pattern, and - determination of a vertical location of the aircraft (2) relative to the runway (4) as a function of the vertical distance ( ). Figure for the abstract: Figure 1

Description

Title of the invention: Method for locating a vertical landing aircraft relative to a runway, method and associated devices

[0001] The present invention relates to a method for locating an aircraft relative to a runway. The present invention also relates to a control method and associated devices, namely a locating device and a runway.

[0002] The invention relates to the field of aircraft, in particular autonomous vertical landing aircraft, more particularly the field of localization of the latter during takeoff and landing.

[0003] It is essential to be able to locate an aircraft in relation to the runway on which it can land or take off in order to guarantee a satisfactory level of safety during the takeoff and landing phases.

[0004] The so-called "vertical" landing of certain aircraft involves specific landing procedures and the use of runways adapted to these procedures commonly called heliport or vertiport.

[0005] Typically, the tracks are circular in shape and have a diameter of approximately 25 meters (m).

[0006] The approach speed of an aircraft seeking to land on such a runway implies a rapid localization of the latter.

[0007] For this purpose, there is known in ILS technology (from the English, "Instrument Landing System") a reference system with regard to the location of an aircraft in relation to a runway in the landing phase.

[0008] This technology uses transmitting antennas located at the end of the runway, the sum of the signals received by the aircraft being characterized by a carrier and a modulation, themselves a function of the lateral and longitudinal offsets of the aircraft relative to the reference approach axis in the vertical and horizontal plane.

[0009] However, this technology is expensive and therefore not widely deployed and does not allow the detection of the possible presence of obstacles on the track.

[0010] Moreover, this technology is not used during takeoff and is not necessarily suitable for a vertical landing.

[0011] There is therefore a need for a method of locating a vertical landing aircraft relative to a runway which is easy to implement.

[0012] To this end, the description describes a method for locating an aircraft relative to a runway on which aircraft can land or take off, the runway having a shape suitable for vertical landing and comprising at least one element reflecting a radio signal, the process comprises the following steps:

[0013] - transmission of a radio signal from the aircraft to the runway,

[0014] - reception of a signal reflected by the track in response to the emitted radio signal,

[0015] - extraction of at least one pattern in the received reflected signal, each pattern being the evolution over time of the radio signal reflected by at least one reflective element composing a group of reflective elements, called a tracking group,

[0016] - calculation of a vertical distance from at least one pattern, the vertical distance being the distance between the aircraft and a runway center along a first direction normal to the runway, and

[0017] - determination of a vertical location of the aircraft relative to the runway in function of the vertical distance.

[0018] According to other advantageous aspects, the localization method comprises one or more of the following features, taken individually or in all technically possible combinations:

[0019] - the vertical distance calculation step comprises the following sub-steps:

[0020] - estimation of a phase shift between two patterns, and

[0021] - calculation of the vertical distance by applying a function to the phase shift estimated, the function associating a vertical distance with a phase shift between two patterns,

[0022] - the step of calculating the vertical distance comprises the following substeps:

[0023] - estimation of the frequency of at least one pattern, and

[0024] - calculation of the vertical distance by applying a function to the frequency estimated, the function associating a vertical distance as a function of the estimated frequency.

[0025] - each reflective element comprises at least two reflectors, the at least two reflectors being aligned or offset from each other along a second direction transverse to the track and along the first direction.

[0026] - the process further comprises the following steps:

[0027] - estimation of two distances: a first distance between the aircraft and a first reflective element and a second distance between the aircraft and a second reflective element;

[0028] - calculation by multilateration of a lateral distance and a longitudinal distance to starting from the first distance, the second distance and the vertical distance, the lateral longitudinal distance being the distance between the aircraft and the center of the runway along a third direction perpendicular to the second direction, and the longitudinal distance being the distance between the aircraft and the center of the runway along the second direction;

[0029] - determination of the aircraft's location as a function of the vertical distance, of the longitudinal distance and the lateral distance.

[0030] - the radio signal belongs to a frequency band chosen from the bands X, K, Ka, Ku and W.

[0031] The description also relates to a method for controlling an aircraft comprising the following steps:

[0032] - localization of the aircraft by implementing a localization method according to the invention,

[0033] - estimation of a percentage risk of the presence of an obstacle on the track from of a ground pattern, the ground pattern being the radio signal reflected by the runway floor, and

[0034] - performing an action to interrupt the landing or takeoff of the aircraft depending on the determined location and the estimated percentage of risk.

[0035] The description also relates to an electronic device for locating an aircraft relative to a runway on which aircraft can land or take off, the runway having a shape suitable for vertical landing and comprising at least one reflective element for a radio signal, the locating device being configured to:

[0036] - to transmit a radio signal from the aircraft to the runway,

[0037] - receive a signal reflected by the track in response to the radio signal issued,

[0038] - extract at least one pattern from the received reflected signal, each pattern being the evolution over time of the radio signal reflected by at least one reflective element composing a group of reflective elements, called a tracking group,

[0039] - calculate a vertical distance from at least one pattern, the vertical distance being the distance between the aircraft and a runway center along a first direction normal to the runway, and

[0040] - determine a vertical location of the aircraft relative to the runway according to of the vertical distance.

[0041] The description also relates to a device for controlling an aircraft relative to a runway on which aircraft can land or take off, the runway having a shape suitable for vertical landing and comprising at least one reflective element for a radio signal, the control device comprising:

[0042] - an aircraft location device according to the invention,

[0043] - a controller configured for:

[0044] - estimating a percentage risk of the presence of an obstacle on the track from a ground pattern, the ground pattern being the radio signal reflected by the runway floor, and

[0045] - to perform an automatic interruption of the landing or takeoff of the aircraft based on the location determined by the tracking device and the estimated risk percentage.

[0046] The description also describes a runway having a shape suitable for vertical landing and comprising two groups of reflective elements for a radio signal arranged on one edge of the runway.

[0047] According to other advantageous aspects, the track comprises one or more of the following features, taken individually or in all technically possible combinations:

[0048] - a reflective element comprises at least two trihedral reflectors;

[0049] - the at least two trihedral reflectors of one of the two groups of elements reflective surfaces are offset from each other along a first direction normal to the track and along a second direction transverse to the track.

[0050] In the following description, a quantity is substantially equal to a value when the quantity is greater than or equal to 90% of the value and the quantity is less than or equal to 110% of the value.

[0051] The invention will become clearer upon reading the following description, given solely by way of non-limiting example and with reference to the drawings in which: - [Fig. 1] [Fig. 1] is a schematic representation of an aircraft equipped with a localization device and landing on a runway, - [Fig.2] [Fig.2] is a flowchart illustrating an example of implementation work of a method for locating an aircraft in relation to a runway, - [Fig. 3] [Fig. 3] is a schematic representation in two planes of an architecture of a reflective element, and - [Fig.4] [Fig.4] is a flowchart illustrating an example of implementation operation of an aircraft control process.

[0052] An aircraft 2 and a runway 4 are shown schematically in [Fig.1].

[0053] An aircraft is a means of transport capable of rising and moving in altitude, within the Earth's atmosphere. For example, an aircraft is a plane, a helicopter, or a drone.

[0054] More specifically, here, aircraft 2 is a vertical takeoff or landing aircraft seeking to land on runway 3.

[0055] For example, a known vertical landing protocol on such a runway is described in the EASA document (PTS-VPT-DSN, available at the following address: “https: / / www.easa.europa.eu / en / document-library / general-publications / prototype-technical-design-specifications-vertiports") and consists of the following sequence of steps: - approach of aircraft 2 towards runway 4 with an angle relative to the ground of runway 4 between 3° and 30°, this angle is commonly called the slope, - arrival of aircraft 2 at an LDP decision point (from the English " Landing Decision Point") located at a longitudinal distance from runway 4 usually between 10 meters and 250 meters, and - landing or go-around of aircraft 2 depending on the situation.

[0056] Alternatively, runway 4 can also be used for the takeoff of aircraft 2.

[0057] Runway 4 has a shape suitable for a vertical landing.

[0058] For example, runway 4 has a disc shape and is reserved for takeoff and aircraft landing.

[0059] In the following description, the location of an object is defined by three coordinates in a given frame of reference.

[0060] Thus, in the remainder of this description, a location of an object with respect to track 4 is defined as the projection of three coordinates of said object into a frame of reference of track 4.

[0061] The reference frame of track 4 is the reference frame formed by three directions orthogonal to each other, the reference frame of track 4 having as its origin the point O with coordinates (0,0,0) in said reference frame.

[0062] A first direction Y is normal to track 4, a second direction X is transverse to track 4 and a third direction Z is perpendicular to the second direction X.

[0063] In the following description, the origin O of the track 4 reference frame also represents the center of the disk formed by track 4.

[0064] In the example of [Fig.1], track 3 comprises a first group of reflective elements 10 and a second group of reflective elements 12.

[0065] In the example of [Fig.1], only two groups of reflective elements 10 and 12 are represented, but this number is not limiting, the number of groups of reflective elements can vary according to the needs, the minimum being one group of reflective elements.

[0066] The first group of reflective elements 10 comprises one or more reflective elements for a radio signal.

[0067] The second group of reflective elements 12 also includes one or more reflective elements for a radio signal.

[0068] For example, the first group of reflective elements 10 comprises a first reflective element 20A and a second reflective element 20B.

[0069] In such an example, the second group of reflective elements 12 comprises a first reflective element 22A and a second reflective element 22B.

[0070] Each reflective element 20A, 20B, 22A and 22B is arranged on the edge of runway 4. The term "edge of runway" includes the contour of runway 4 but also a nearby area which may vary from 10 to 100 meters around said runway 4.

[0071] In the example described, each group of reflective elements 10 and 12 comprises, respectively, two reflective elements 20A, 20B, 22A and 22B, but this number is not limiting, the number of reflective elements can vary according to the needs.

[0072] For example, each reflective element 20A, 20B, 22A and 22B is located 25 meters from a point in the main area of ​​runway 4 in the Z direction.

[0073] As an optional addition, the first reflective elements 20A and 22A are respectively spaced at least 3 meters apart from the second reflective elements 20B and 22B.

[0074] Typically, each reflective element 20A, 20B, 22A and 22B comprises at least two reflectors.

[0075] A reflector is a device that allows an incident electromagnetic wave, and especially a radar signal, to be reflected.

[0076] For example, each reflector is a trihedral reflector. A trihedral reflector is well suited for radar waves because it has the property of generating radar echoes of relatively high amplitude.

[0077] However, any form of reflector is conceivable here, including parabolic, planar or elliptical reflectors, as well as reflectors using passive, active electronic components, or those with frequency-selective properties.

[0078] For example, such reflectors include Van Atta grating type reflectors or Luneberg lenses.

[0079] A plurality of reflectors composing a single reflective element 20A, 20B, 22A or 22B allows said reflective element to generate interference specific to the reflectors composing it upon reception of an incident signal. Thus, for a fixed incident signal, the reflected signal constitutes a unique signature of the reflective element.

[0080] A longitudinal spacing distance Despiong is defined for each reflective element 20A, 20B, 22A and 22B as the distance between the nearest point of a reflective element 20A, 20B, 22A and 22B and a point in the main area of ​​track 4 along the X direction.

[0081] Typically, the longitudinal spacing distance DeSpjmig is between 10 meters and 100 meters.

[0082] Advantageously, the longitudinal spacing distance Despiong is equal to 15 meters.

[0083] Aircraft 2 includes a location device 30 configured to transmit a radio signal towards runway 4 and receive a signal reflected by runway 4 (and more specifically from at least one reflective element 20A, 20B, 22A or 22B) in order to deduce a location of aircraft 2 in the reference frame of runway 4.

[0084] The location device 30 includes a radio transceiver 40 and a computer 50.

[0085] The radio transceiver 40 is configured to transmit a signal radio transmission from aircraft 2 to runway 4 and receive a signal reflected by runway 4.

[0086] For example, the radio transceiver 40 is a radar.

[0087] According to a preferred embodiment, the radio transceiver 40 is a continuous wave radar.

[0088] Such a radar is more often referred to as FMCW radar, which refers to the corresponding English name of "Frequency Modulated Continuous Wave".

[0089] Such a radar operates here with millimeter or centimeter waves.

[0090] Preferably, the radio transceiver 40 is suitable for transmitting or receiving signals with a frequency selected from the bands: X, K, Ka, Ku and W.

[0091] For such a radar, transmission and reception are almost simultaneous.

[0092] Advantageously, the signals emitted or received by the radio transceiver 40 have a frequency substantially equal to 15GHz, 24 GHz, 77GHz or 95 GHz.

[0093] In the example of [Fig.1], the calculator 50 includes, for example, a processor 52 and a memory 54 associated with the processor 52.

[0094] The computer 50 is configured to process signals from the radio transceiver 40.

[0095] The calculator 50 is an electronic circuit designed to manipulate and / or transform data represented by electronic or physical quantities in registers of the calculator and / or memories into other similar data corresponding to physical data in register memories or other types of display devices, transmission devices or storage devices.

[0096] As specific examples, the calculator 50 is implemented in the form of a programmable logic component, such as an FPGA (Field Program Gate Array), or an integrated circuit, such as an ASIC (Application Specified Integrated Circuit).

[0097] Alternatively, when the method is implemented in the form of one or more software programs, that is to say, in the form of a computer program, also called a computer program product, it is further capable of being stored on a computer-readable medium, not shown. The computer-readable medium is, for example, a medium capable of storing electronic instructions and being connected to a bus of a computer system. By way of example, the readable medium is an optical disc, a magneto-optical disc, ROM, RAM, any type of non-volatile memory (for example, FLASH or NVRAM), or a magnetic card. A computer program comprising software instructions is then stored on the readable medium.

[0098] The operation of the localization device 30 is now described with reference to [Fig.2] which illustrates an example of the implementation of a localization method.

[0099] The localization process comprises an emission step 100, a reception step 200, an extraction step 300, a calculation step 400 and a determination step 500.

[0100] During the first transmission stage 100, the radio transceiver 40 transmits a radio signal from the aircraft 2 to the runway 4.

[0101] The radio signal thus emitted interacts with the reflective elements 20A, 20B, 22A and 22B, each returning a reflected signal towards the aircraft 2 and more specifically towards the radio transceiver 40.

[0102] During the reception step 200, the radio transceiver 40 receives a signal reflected by track 3.

[0103] The reflected signal is then one of the signals reflected by the reflective elements 20A, 20B, 22A or 22B or a sum of one or more of said signals.

[0104] Advantageously, in the embodiment in which the radio transceiver 40 is an FMCW radar, the receiving stage 200 is implemented in parallel with the transmitting stage 100.

[0105] During the extraction step 300, the computer 40 extracts at least one pattern from the received reflected signal.

[0106] A pattern is the evolution over time, over a fixed time window, of a radio signal reflected by at least one reflective element.

[0107] In addition, the reflective element(s) from which at least one pattern originates then form a group of reflective elements called a spotting group in the rest of this description.

[0108] For example, the calculator 40 extracts two patterns from the first reflective element 20A and the second reflective element 20B composing the first group of reflective elements 10 thus forming the identification group.

[0109] Thus, thereafter, the terms "group of reflective elements" and "spotting group" refer to the same group.

[0110] However, the spotting group may change during landing or takeoff depending on the evolution of the distance between aircraft 2 and runway 4 (for example, the group of reflective elements 12 may become the spotting group). [YES] .

[0112] Each of the patterns is characteristic of the reflective element 20A or 20B and takes, for example, the form of an oscillation of the power received over time when the reflective element 20A or 20B is composed of two identical reflectors positioned side by side.

[0113] For example, the localization device 30 includes a memory capable of storing a plurality of reference patterns corresponding to a reflected radio signal characteristic of a reflective element.

[0114] In particular, the localization device 30 comprises a plurality of reference patterns corresponding to specific localization conditions of the aircraft 2 with respect to the reflective element in the runway 4 reference frame.

[0115] Thus, the calculator 50 can recognize a pattern in a received signal by comparing it to the plurality of reference patterns.

[0116] During calculation step 400, the calculator 50 obtains a vertical distance Dy.

[0117] The vertical distance Dy is defined as the distance between aircraft 2 and runway 4 along the first direction Y. Generally, the vertical distance Dy corresponds to the height of aircraft 2 relative to runway 4.

[0118] Calculator 50 calculates the vertical distance Dy as a function of at least one extracted pattern.

[0119] The calculation step 400 comprises an esthnation substep 410 and a calculation substep 420.

[0120] During the estimation substep 410, the computer 34 estimates a phase shift between a first reflected pattern and a second reflected pattern.

[0121] Typically, the first reflected pattern corresponds to the signal reflected by the first reflective element 20A and the second reflected pattern corresponds to the signal reflected by the second reflective element 20B.

[0122] As a reminder, reflective elements 20A and 20B form the identification group.

[0123] For example, the calculator 50 looks for a sequence of the first reflected pattern in the second reflected pattern, the first reflected pattern being extracted before the second reflected pattern.

[0124] During the calculation substep 420, the calculator 50 calculates the vertical distance Dy by applying a function f to the estimated phase shift.

[0125] The function f is a function associating a vertical distance Dy with a phase shift between two reflected patterns.

[0126] For example, the associated distance values ​​are contained in a table stored by a memory contained in the locating device 30.

[0127] During the determination step 500, the computer 50 determines the location y& of the aircraft 2 as a function of the vertical distance Dy.

[0128] For this purpose, the computer 50 determines the location yA of the aircraft 2 in the reference frame of runway 4.

[0129] The calculator 50 obtains the location T 4 as the difference between the vertical distance Dy and a distance y^ between the tracking group and the center O of track 4 along the first direction Y.

[0130] For example, the distance is equal to the distance between the first reflective element 20A and the center O of track 4.

[0131] Alternatively, the distance is equal to the distance between the second reflective element 20B and the center O of track 4.

[0132] As a further alternative, the distance is equal to the distance between an average of the locations of the reflective elements 20A, 20B in the coordinate system of track 4 and the center O of track 4.

[0133] The calculation of y a is mathematically written as follows:

[0134] y = Dy-y z* IV

[0135] Typically, the calculator 50 considers that the height of the tracking group in the track 4 coordinate system is zero, which simplifies the calculation of;

[0136] yA-Dy

[0137] Thus, the described process makes it possible to obtain the location of aircraft 2 in relation to runway 4.

[0138] Advantageously, the localization method described is simple to implement and involves few constraints for track 4 because only the characteristics of the reflectors composing the reflective elements 20A, 20B, 22A and 22B need to be determined.

[0139] Figure 3 represents an embodiment in which the reflective element 20A comprises at least two trihedral reflectors 60A and 60B and their characteristics to be determined: - a: length of the sides of the reflectors, - Ex; longitudinal distance between reflectors 60A and 60B along the X direction, - Ey; vertical distance Ey between reflectors 60A and 60B along the Y direction, And - Ez; lateral gap E~ between reflectors 60A and 60B along the Z direction.

[0140] First, to determine the lengths of the sides of reflectors 60A and 60B, it is possible to use the radar cross-sectional area (RCA) or radar cross section.

[0141] The SER is an inherent physical property of objects indicating the relative importance of the reflecting surface of an electromagnetic beam that they cause.

[0142] For a given reflector, its RCS is defined by the following equation: [° 14 3] SER =

[0144] Where: - a denotes the length of the sides of the reflector, - 2 denotes the wavelength of the signal emitted by the radar.

[0145] Thus, for a pair of reflectors 60A and 60B, the amplitude of the oscillation of the signal reflected by the reflecting element 20A depends on the RCS of each of the reflectors 60A and 60B.

[0146] Therefore, the sum of the SERs of the two reflectors 60A and 60B must satisfy the following two equations:

[0147] \SERy-SE&2\ <tr^

[0148] SER{ + SER2= Ï^SERy-SER^

[0149] Or: - SERy designates the SER of the first 60A reflector, - SER2 designates the SER of the second 60B reflector, - r^armïn(ump\nYdxidist) denotes the minimum SER detectable by the radio transceiver 40 at the greatest envisaged operating distance (for example, 1 kilometer).

[0150] By choosing a side length a that allows these two equations to be satisfied, the signal reflected by the reflecting element 20A remains detectable.

[0151] Moreover, the total SER having a difference of 1OdB between its minimum and maximum values ​​allows a sufficient measurement range to be maintained.

[0152] Typically, a 60A reflector with sides of 360 millimeters and a 6B reflector with sides of 380 millimeters may be suitable.

[0153] The longitudinal deviation Ex must be less than 3 meters for the radial resolution of the radio transceiver 40 to allow the interference to be observed.

[0154] Indeed, the radial resolution of such a radio transceiver 40 is on the order of 3 meters and a longitudinal deviation Ex greater than 3 meters would imply that the localization device 30 would receive a reflected signal for each reflector and not for each reflective element 20A, 20B, 22A and 22B.

[0155] Moreover, the angular resolution of such a radio transceiver 40 is on the order of 2° and explains the lateral spacing distance Despja( greater than 3 meters without which two signals from two reflective elements could be confused.

[0156] Next, the lateral deviation allows for increased sensitivity for a lateral location of aircraft 2 relative to runway 4, said lateral location will be described later.

[0157] Finally, the vertical gap Ey makes it easy to observe the oscillations of the reflected signal while remaining sensitive to vertical shifts.

[0158] However, for distances between aircraft 2 and runway 4 of less than 350 meters, oscillations are more observable for reflectors offset by a vertical gap Ey of the order of 15 centimeters while a vertical gap Ey of the order of 1 meter is preferable for distances greater than 350 meters.

[0159] Thus, for example, the first group of reflective elements 10 has reflectors offset by a vertical gap Ey substantially equal to 15 centimeters.

[0160] Still in this example, the second group of reflective elements 12 has reflectors offset by a vertical gap Ev approximately equal to 1 meter.

[0161] As explained previously, the spotting group can change depending on the distance between aircraft 2 and the center O of runway 4. Thus, for example, the first group of reflective elements 10 can serve as the spotting group up to a distance of 350 meters between aircraft 2 and the center O of runway 4 along the X direction. In such an example, the second group of reflective elements 12 will then be the spotting group if the distance between aircraft 2 and the center O of runway 4 along the X direction is less than 350 meters.

[0162] Such dimensions are dimensions easily achievable in practice.

[0163] Modifying an existing runway thus represents a moderate cost for an airport wishing to equip itself with it and is easy to implement

[0164] Similarly, the cost of installing the location device 30 is also moderate and the modifications to be made are minor, these most often amounting to a simple reprogramming of an already existing computer.

[0165] In addition, the method has a hybrid character since it makes it possible to guarantee a precise localization of the aircraft 2 in the landing and takeoff phases.

[0166] Other embodiments of the process just described are conceivable.

[0167] For example, the steps can be implemented in a different order or in parallel where technically possible.

[0168] According to another example, calculation step 400 is carried out differently.

[0169] In such an example, the calculation step 400 comprises an esthnation substep and a calculation substep.

[0170] During the first estimation substep, the calculator 50 estimates an oscillation frequency of at least one extracted motif.

[0171] If several patterns have been extracted, the calculator 50 estimates that the oscillation frequency is an average or a weighted average of all the oscillation frequencies of the different patterns.

[0172] During the calculation substep, the calculator 50 calculates the vertical distance Dy by applying a function h to the oscillation frequency.

[0173] The function h is a function associating a vertical distance Dy with an oscillation frequency.

[0174] For example, the associated distance values ​​are contained in a table stored by a memory contained in the locating device 30.

[0175] According to yet another example, calculation step 400 is carried out in a different way.

[0176] In such an example, the calculation step 400 includes a determination substep and a calculation substep.

[0177] During the determination substep, the calculator 50 determines a sub-motif extracted from one of the reflected motifs for which a correlation with a theoretical motif is maximal.

[0178] During the calculation substep, the calculator 50 calculates the vertical distance Dy by applying a function w to the sub-motif extracted from one of the reflected motifs.

[0179] The function w is a function associating a vertical distance Dy with an extracted sub-motif.

[0180] The localization process may also include additional steps.

[0181] For example, the localization method further includes a step of determining a lateral distance Dz and a longitudinal distance Dx of aircraft 2 relative to runway 4.

[0182] During the determination step, the computer 50 estimates two distances: a first distance d between the aircraft 2 and the first reflective element 20A and a second distance d2 between the aircraft 2 and the second reflective element 22B.

[0183] The distances dY and d2 are determined by the FMCW radar, from the received radio signal and using classical radar range measurement algorithms.

[0184] Thus, during the determination step 500, the computer 50 calculates the longitudinal distance Dx and the lateral distance Dz of the aircraft 2.

[0185] For example, the lateral distance Dz and the longitudinal distance Dx are calculated by multilateration from the distances d1 and d2 and the vertical distance Dy, the longitudinal distance Dz being the distance between aircraft 2 and the center O of runway 4 along a third direction Z perpendicular to the second direction (X) and the distance longitudinal Dx being the distance between aircraft 2 and the center O of runway 4 along the second direction X.

[0186] In this example, the location / i of aircraft 2 is the location ( J f Dx, Dy, D^_

[0187] The localization method can also be used in other methods and in particular a control method.

[0188] In such a case, aircraft 2 is provided with additional elements. For example, aircraft 2 further comprises a control device including the location device 30 of [Fig. 1] and a controller.

[0189] The controller is configured to process signals from the location device 30.

[0190] From a hardware point of view, the controller is similar to the calculator 50 of the locating device 30, so the remarks made for the calculator 50 also apply here.

[0191] Thus, in particular, as with calculator 50, the controller includes a processor and a memory associated with the processor.

[0192] The control device is configured to implement a control method now described with reference to [Fig.4].

[0193] The control method aims to control aircraft 2, i.e. to ensure its proper progress during a landing or takeoff phase.

[0194] The control process includes a step of locating the aircraft relative to the runway during which the steps of the locating process of the [Fig.2] are implemented.

[0195] The method further comprises an estimation step 600 of a percentage risk of presence of an obstacle on the track and an alert step 700.

[0196] During the estimation step 600 of a percentage risk of the presence of an obstacle on the runway, a ground pattern is received by the radio transceiver 40, the ground pattern being the radio signal reflected by the ground of runway 4.

[0197] For example, the received floor pattern is compared to a reference floor pattern stored in memory and the percentage of risk is determined based on the differences in amplitude and / or shape of the two patterns.

[0198] During alert step 700, the control device issues an alert to an operator based on the estimated percentage and location of aircraft 2 relative to runway 4.

[0199] Typically, for the same ground pattern received, the percentage of risk will be higher if the location of aircraft 2 is close to runway 4.

[0200] For example, the alert takes the form of a notification on a screen for the operator

[0201] The operator here is a pilot, a co-pilot or a member of the flight crew.

[0202] According to another example, the operator is the air traffic control (ATC) service and can authorize or prohibit takeoff or landing depending on the alert received.

[0203] According to another example, the system automatically interrupts the landing or takeoff when the percentage of risk exceeds a certain threshold.

[0204] The control process thus makes it possible to guarantee the safety of the aircraft in the conditions of landing and takeoff while preventing the risks of collision with possible obstacles on runway 4.

[0205] The control procedure remains easy to implement.

Claims

Demands

1. A method for locating an aircraft (2) relative to a runway (4) on which aircraft (2) can land or take off, the runway (4) having a shape suitable for vertical landing and comprising at least one reflective element (20A, 20B, 22A, 22B) for a radio signal, the method comprising the following steps: - transmission (100) of a radio signal from the aircraft (2) to the runway (4), - reception (200) of a signal reflected by the runway (4) in response to the transmitted radio signal, - extraction (300) of at least one pattern in the received reflected signal, each pattern being the evolution over time of the radio signal reflected by at least one reflective element (20A, 20B, 22A, 22B) comprising a group of reflective elements, referred to as a tracking group (10), - calculation (400) of a vertical distance (Dy) from at least one reason,the vertical distance (Dy) being the distance between the aircraft (2) and a center (O) of the runway (4) along a first direction (Y) normal to the runway (4), and - determination (500) of a vertical location (3a) of the aircraft (2) relative to the runway (4) as a function of the vertical distance (#>).,

2. A localization method according to claim 1, wherein the calculation step (400) of the vertical distance (Dy) comprises the following substeps: - estimation of a phase shift between two patterns, and - calculation of the vertical distance (Dy) by applying a function to the estimated phase shift, the function associating a vertical distance (Dy) with a phase shift between two patterns.

3. A localization method according to claim 1, wherein the calculation step (400) of the vertical distance (Dy) comprises the following substeps: - estimation of a frequency of at least one pattern, and - calculation of the vertical distance (Dy) by applying a function to the estimated frequency, the function associating a vertical distance (Dy) as a function of the estimated frequency.

4. A localization method according to any one of claims 1 to 3, wherein each reflective element (20A, 20B, 22A, 22B) comprises at least two reflectors (60A, 60B), the at least two reflectors (60A, 60B) being aligned or offset from one another along a second direction (X) transverse to the track (4) and along the first direction (Y).

5. A localization method according to any one of claims 1 to 4, the method further comprising the following steps: - estimation of two distances: a first distance (d) between the aircraft (2) and a first reflective element (20A, 20B, 22A, 22B) and a second distance ( < / 3) entre l'aéronef (2) et un deuxième élément réfléchissant (20A, 20B, 22A, 22B) - calcul par multilatération d’une distance latérale (Dz) et d’une distance longitudinale (Dx) à partir de la première distance (d^, de la deuxième distance (^2) et de la distance verticale (#y), la distance latérale (ZX) étant la distance entre l’aéronef (2) et le centre (0) de la piste (4) selon une troisième direction (Z) perpendiculaire à la deuxième direction (X), et la distance longitudinale (Dx) étant la distance entre l’aéronef (2) et le centre (0) de la piste (4) selon la deuxième direction (X),- determination of the aircraft's location (2) as a function of the vertical distance (Dy), the longitudinal distance (Dx) and the lateral distance (Dz).

6. A localization method according to any one of claims 1 to 5, wherein the radio signal belongs to a frequency band selected from the X, K, Ka, Ku and W bands.

7. Method for controlling an aircraft (2), the control method comprising the following steps: - locating the aircraft by implementing a locating method according to any one of claims 1 to 6, - estimating (600) a percentage risk of the presence of an obstacle on the runway (4) from a ground pattern, the ground pattern being the radio signal reflected by the ground of the runway (4), and - carrying out (700) an action to interrupt the landing or takeoff of the aircraft (2) according to the determined location and the estimated percentage risk.

8.

9. An electronic device (30) for locating an aircraft (2) relative to a runway (4) on which aircraft (2) can land or take off, the runway (4) having a shape suitable for vertical landing and comprising at least one reflective element (20A, 20B, 22A, 22B) for a radio signal, the locating device (30) being configured to: - to transmit a radio signal from the aircraft (2) towards the runway (4), - to receive a signal reflected by track (4) in response to the emitted radio signal, - extract at least one pattern in the received reflected signal, each pattern being the evolution over time of the radio signal reflected by at least one reflective element (20A, 20B, 22A, 22B) composing a group of reflective elements, called the tracking group (10), - calculate a vertical distance (Dy) from at least one pattern, the vertical distance (Dy) being the distance between the aircraft (2) and a center (O) of the runway (4) along a first direction (Y) normal to the runway (4), and - determine a vertical location (-^) of the aircraft (2) relative to the runway (4) as a function of the vertical distance (Dy). Aircraft control device (2), relative to a runway (4) on which aircraft (2) may land or take off, the runway and comprising at least one reflective element (20A, 20B, 22A, 22B) for a radio signal, said device comprising: - an aircraft location device (30) according to claim 8, and - a controller configured for: • estimate a percentage risk of an obstacle being present on the runway (4) based on a ground pattern, the ground pattern being the radio signal reflected by the runway ground (4); and • perform an automatic aborted landing or takeoff action of the aircraft (2) based on the location determined by the location device (30) and the estimated risk percentage.

10. Runway (4) on which aircraft (2) can land or take off, the runway (4) having a shape suitable for vertical landing and comprising two groups of reflective elements (10, 12) for a radio signal arranged on one edge of the runway (4).

11. Track (4) according to claim 10, wherein a reflective element (20A, 20B, 22A, 22B) comprises at least two trihedral reflectors (60A, 60B).

12. Track (4) according to claim 11, wherein the at least two trihedral reflectors (60A, 60B) of one of the two groups of reflective elements (10, 12) are offset from each other along a first direction (Y) normal to the track (4) and along a second direction (X) transverse to the track (4).