• 专利附录
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    • 专利摘要:
    The radar being able to be fixed laterally on the fuselage of an aircraft (10) and to realize the detection of obstacles in the collision course with a part of the aircraft facing said radar, it comprises at least one antenna line of transmission and several antennal reception channels (320, 321, 322, 323) disposed in the same plane, the wave shape and the angular coverage range of said radar being a function of the speed of the aircraft, the processing means said radar performing the following steps: Establishing (511) in the radar frame of a first distance / Doppler map for separating echoes according to distance resolution and Doppler cells on several receiving antenna channels; Establishing (512) a second distance / Doppler map of reduced dimensions relative to the first, by selecting in the latter a subset of distance / Doppler resolution cells corresponding to the possible positions of targets likely to collide with the wing of the plane; Establishing (37) new distance / Doppler maps by beamforming by calculation on the subsets of distance resolution cells retained on each receiving antenna path; Time integration (514), on each formed beam, of several successive distance / Doppler maps.
    公开号:FR3013849A1
    申请号:FR1302731
    申请日:2013-11-26
    公开日:2015-05-29
    发明作者:Pascal Cornic；Bihan Patrick Le；Yves Audic
    申请人:Thales SA；
    IPC主号:
    专利说明:

    [0001] The present invention relates to an anticollision radar, in particular for rolling aircraft. BACKGROUND OF THE INVENTION The invention relates to an anti-collision system using at least two anti-collision radars. More specifically, the invention is particularly applicable for the detection of obstacles on the ground to avoid any collision between an aircraft taxiing and these obstacles. The density of airport traffic is increasingly important both in the air and on the ground. Collisions between aircraft and various ground obstacles are becoming more frequent, especially when an aircraft reaches a garage position from an airstrip at an airport. For example, on a large aircraft the wings and the reactors are difficult to see by the pilot of the aircraft. The wings and reactors are therefore particularly exposed to shocks with different objects such as: - other aircraft; - airport facilities; - Technical vehicles from the airport. This type of incident, in addition to the cost of repairing the aircraft, causes the aircraft to remain grounded. This grounding of the aircraft is pecuniarily prejudicial to the company owning this aircraft. To overcome these collision problems, airports are equipped with various means for centralized management of ground traffic. These means include airport surveillance radars, radio means, GPS and transponders. However, the density of the traffic on the airports is such that these means are insufficient to ensure the final guidance of the aircraft to their garage position. Moreover these means are often ineffective in foggy weather for example and generally when weather conditions are bad or it is dark. Human intervention is then necessary to prevent the aircraft any risk of collision with objects on the ground in a taxiing area.
    [0002] Another way of avoiding collisions between an aircraft and objects on the ground is to equip the aircraft with autonomous collision avoidance devices complementary to existing means on the airport. These anti-collision devices make it possible in particular to ensure the protection of the aircraft over a very short distance with respect to fixed objects or having a low speed of movement. Among these means, devices including cameras are used in particular. Cameras, however, are inefficient with poor weather conditions. In addition, the camera-based devices do not allow the pilot to have precise information on the distance between the aircraft and a potential obstacle, nor on the relative speed of the aircraft with respect to the obstacle. To handle a wide range of angles with sufficient depth of field in a very short time, the cameras can be equipped with zooms or fast electronic pointing devices. The cameras thus equipped are complex to implement and do not have the reliability necessary for an anticollision device. Other devices based on LIDAR, meaning Light Detection And Ranging 20 in English language, can be used. However, anti-collision devices using LIDARs have the same disadvantages as devices using cameras. Acoustic sensors can also be implemented in anti-collision devices. Acoustic sensors, however, are very sensitive to interference and disturbances in the propagation of acoustic waves. All this makes the use of acoustic sensors difficult in an airport environment. The range of acoustic sensors is also too low, of the order of a few meters, to suit an anticollision device. Other anti-collision devices use radar technologies such as ultra wide band radars. These devices may interfere with other equipment such as on-board navigation equipment. Ultra-wide band radars are therefore subject, when authorized to use, to very restrictive regulations, in particular limiting the power of the emitted wave. The limitation of the power of emission of these radars considerably reduces their field of use and in particular their range. Moreover, these radars do not possess, individually, angular discrimination capacity. They do not allow a sufficiently precise location of obstacles. Such radars have interesting angular discrimination capabilities only when they are grouped in a large network, which is impossible to implement on board an aircraft.
    [0003] The patent application FR 07 01927 describes an effective solution for dealing with the risk of collision, in which a system of automobile radar sensors operating in the millimetric band is used. This solution, although effective, may be confronted in view of the number of sensors used and their installation position, to both cost and integration constraints which make it difficult to implement on some carriers. An object of the invention is in particular to overcome the aforementioned drawbacks. To this end, the object of the invention is an anticollision radar for a taxi vehicle, said radar being able to be fixed laterally on the fuselage of a vehicle and to realize the detection of obstacles in a collision course with a part of the vehicle. Apparatus facing said radar, it comprises at least one antennal transmission channel emitting a wave of the FMCW type and several antennal reception channels arranged in the same plane, the shape of said wave and the angular coverage range of said radar being depending on the speed of the machine, the processing means of said radar performing at least the following steps: Establishment in the radar marker of a first distance / Doppler map for separating the echoes according to distance and Doppler resolution cells on said plurality of antennal receiving channels; Establishing a second distance / Doppler map of reduced dimensions relative to the first, by selecting in the latter a subset of Doppler and distance resolution cells corresponding to the possible positions of targets likely to collide with said part. the machine, said selection being a function of the speed of the machine; Establishment of new distance / Doppler beamforming maps by calculation on the subsets of distance resolution cells retained on each receiving antenna path, so as to separate the angular observation beam in the plane of the antennal channels at minus two beams; Time integration, on each formed beam, of several successive distance / Doppler maps obtained in the preceding step in order to obtain a final distance / Doppler map for each beam, the integration time being a function of the waveform used; these steps being followed by at least one detection step in each of the beams formed from said final distance / Doppler map. In the detection step, the estimation of the azimuth angle of said target is for example performed for each pixel detected in the final distance / Doppler map, by comparing the level received on the distance / Doppler maps of two adjacent formed beams according to an amplitude monopulse operator. The detection step is for example followed by a step of tracking the targets detected in the reference mark of said radar. The radar performs, for example, a step of changing a geographical reference point, passing from the reference point linked to the radar to a reference point linked to said part of the radar, to estimate the coordinates of the targets in the reference frame linked to said part. The plane of the antennal reception channels is horizontal, for example. The beam formation can be performed on an angular range of +/- 450 in the plane of the antenna channels, with respect to a line of sight, adapted to be perpendicular to the axis of the fuselage of the machine. In one possible embodiment, the antennas of the antennal receiving channels on which the beamforming is performed by the calculation are spaced from each other by more than half a wavelength, the ambiguity of angular position of a target being raised by the Doppler frequency of the distance / Doppler cell of said target.
    [0004] The first distance / Doppler map is for example obtained after compression in distance and Doppler compression of said wave of the FMCW type. In a particular embodiment, the radar receiving system 5 comprises four antenna channels. The radar operates for example in the millimeter range. In a particular embodiment, it operates in the 76 to 77 GHz frequency band. Advantageously, the machine may be an aircraft, said part being for example a wing end of the aircraft. The invention also relates to an anti-collision system for a taxiing airplane, said system comprising at least two radar systems such as that previously described, installed laterally each one side of the fuselage. In one possible embodiment, each radar is installed in front of the wing, fixed for example at the location of a window near the cockpit. Other features and advantages of the invention will become apparent with the aid of the description which follows, given with reference to the appended drawings which represent: FIG. 1, an example of an anti-collision system according to the invention applied to an aircraft taxiing by a view from above; Figure 2, the previous system with a view from the front of the aircraft; FIG. 3 is a schematic diagram of an exemplary radar according to the invention at the transmission and reception channels; FIG. 4, an example of four waveforms used by a radar according to the invention as a function of the speed of the carrier; FIG. 5, the possible steps implemented by the processing of a radar according to the invention; Figure 6, establishing a first distance / Doppler map; Figure 7, an illustration of the Doppler resolution; FIG. 8, the establishment of a second distance / Doppler map of reduced size with respect to the first; Figures 9a and 9b, illustrations of detection domains; Figures 10a and 10b are examples of beam formations; FIG. 11, an illustration of a step of integrating a distance / Doppler map; FIG. 12, an illustration of a step of detecting and estimating position and target speed; FIG. 13, an illustration of the passage from a marker linked to a radar to a marker linked to the end of an airplane wing. FIG. 1 illustrates an example of an anti-collision system according to the invention, installed on an airliner. This system makes it possible in particular to avoid shocks on the end of the wings and possibly on the reactors. The system is composed of two sensors 1, 2 according to the invention, radar type, laterally installed each one side of the fuselage of the aircraft 10. The radars 1, 2 are oriented along a line of sight 8, 9 substantially perpendicular to the fuselage axis so that their beams 3, 4 cover the areas in front of the wing. Each radar is for example placed in the vicinity of the cockpit so as to detect obstacles in the collision course with the end of the wing 5, 6. It can in particular be installed in the location of a porthole. The treatment according to the invention which will be described later advantageously avoids the placement of the radars on the ends of the wings. This same treatment makes it possible to limit the installation of a single radar by side of the fuselage. Each radar is autonomous and delivers for example alert information directly to the pilot, without the need to merge the information of several radars. The coverage area of the radars is optimized to detect obstacles as far as possible and continuously as close as possible to the end of the wing. Thus, a radar 1, 2 has a wide field in azimuth, for example of the order of 90 °. More particularly, taking into account on the one hand the installation geometry and on the other hand the maximum attainable angular aperture for a fixed radar antenna, the angular coverage of the radar in the horizontal plane extends for example from +/- 45 ° along the line of sight 8, 9. Under these conditions, the protection of the end of the wing is provided from a zero distance to a maximum distance Dmax, typically from 90 meters, corresponding to the radar range Rmax of the order of 70 meters. Given the braking distances required to reach the stopping of the carrier, the collision avoidance system must for example be effective up to a speed of the order of 10 meters / second. Figure 2 shows the radar beams 3, 4 in elevation. In the vertical plane, the angular aperture of the antenna of a radar 1, 2 and the direction of its beam are chosen to illuminate widely the end of the wing while reducing the illumination of the ground. Typically, for a distance between the radar and the end of the wing of the order of 50 meters, an opening beam of about 8 ° in elevation pointed in the direction of the end of the wing 10 allows to obtain a vertical coverage of +/- 3.5 meters centered on the end of the wing, which is a good compromise for large aircraft whose wingtips are located at a height between 6 and 8 meters from the ground. FIG. 3 presents the schematic diagram of an anticollision radar 1, 2 according to the invention. The radar used may advantageously be a radar of the type described in patent application EP 0863409, operating for example at 77 GHz. The radar has at least one antenna transmission channel 31 and several antenna reception channels 32 distributed preferably in the same plane, horizontal. In one possible embodiment, the radar comprises a transmission channel and four antenna channels 320, 321, 322, 323 as illustrated in FIG. 3. Thus the radar comprises a transmitter 35 and four receivers 36. Each reception channel comprises a digital analog converter 34, the digitized received signals are sent to a computer 37 performing beamforming by calculation. The antenna, comprising the antenna transmission channels 31 and reception 32, may be of the printed circuit type. The antenna is made so that it covers a wide field in the horizontal plane, for example 90 ° and a narrow field 30 in the vertical plane, for example 8 °. The radar as shown in FIG. 3 is capable of forming by treatment four adjacent partially overlapping beams, each having an opening of the order of 30 ° in the horizontal plane. This example typically corresponds to a situation where the receiving antennas are separated in the horizontal plane by a space corresponding to half a wavelength, and where four beams of the order of 30 ° of aperture are formed every 30 °, the entire receiving domain covering about 120 °. The radar uses a waveform of FMCW type (continuous wave frequency modulation) whose characteristics are adapted to the need of the aircraft application, relative to the resolution required. In order to optimize both the ambiguity function of the radar and the signal-to-noise ratio to the different collision hypotheses, the processing adapts the waveform to the current speed of the carrier.
    [0005] FIG. 4 illustrates an exemplary embodiment in which four waveforms FO 0, F 01, F 02 and F 03 represented by curves 40, 41, 42, 43. Each curve expresses the linear variation of frequency as a function of time t according to a period of time. recurrence Tr different for each of the waveforms, a rest period 49 during which the frequency is zero being provided between each variation, in particular to stabilize the reception loop. The period Tr is equal to the duration of the ramp of the waveform increased by the rest time 49. Similarly, the amplitude of modulation of the ramp AF varies from one waveform to another.
    [0006] According to the invention, the waveform of the radar is slaved to one of these forms F00, F01, F02, F03 as a function of the speed of the carrier. More particularly, the characteristics of the waveform are a function of the speed of the carrier, these characteristics essentially being the duration of the AT ramp and the AF modulation band. An example of four waveforms F00, F01, F02, F03 is presented in the appendix. At a constant processing load, it is advantageous at high speed, where far-distance detection is sought, to favor the Doppler resolution of the radar at the expense of the resolution distance. On the contrary, at low speed it is preferable to use a high resolution distance, the separation by speed being poorly discriminating. This aspect will be described later with regard to the processing carried out on the signal received by the radar. FIG. 5 illustrates the processing steps performed by a radar according to the invention in the case of a four-way embodiment of reception.
    [0007] In a first phase 51, the process decomposes the environment seen by each of the antennal reception channels 320, 321, 322, 323 along two axes, a distance axis and a Doppler axis, to form a first map of the amplitude-coded received signals. and phase. At the end of this first phase, the radar performs a detection step and the location 52, then a tracking step 53 and finally a step 54 passage in a reference linked to the end of the wing. In the first phase 51, the radar performs for each antennal channel, a step 511 of compression in distance and in Doppler, a step 512 of selection of a distance-Doppler zone, a step 37 of formation of beam by the computation then a step 514 of integration of the distance-Doppler map. FIG. 6 illustrates the distance and Doppler compression 511. This step makes it possible to establish in the radar coordinate system a distance / Doppler map making it possible to separate the echoes according to distance and Doppler resolution cells on the antennal reception paths distributed in FIG. the horizontal plane. The compression is carried out after demodulation of the signal received by the transmission and coding signal. It itself has two stages. The first step consists in performing the Fast Fourier Transform Distance 62 (FFT) compression over a NFFDD time depth corresponding to the modulation duration of each of the frequency ramps 61. In each distance box 63, a distance value biased by the Doppler effect. The distance FFTs of this first step are therefore followed in a second FFT Doppler step to correct this bias. The second step therefore makes it possible to analyze the signal received in each of the distance cells 63 thus formed by performing a second Fast Fourier transform 64 over a time depth corresponding to a number NFFTDop of successive ramps. At the end of this second step, there is obtained on each receiving antenna a distance-doppler map 65 of dimension NFFDD x NFFTDop. The angular distance treatment and the Doppler treatment can be reversed, that is to say that one can start by performing Doppler FFTs and then distance FFTs.
    [0008] Target separation on the Doppler axis is used to separate signals according to their direction of arrival, in accordance with the Doppler filtering lobe refinement principle according to a non-focused synthetic antenna processing. Indeed, each of the columns of this distance-Doppler matrix 65 can be assimilated for the fixed echoes to a sub-beam in a given direction in azimuth. Figure 7 illustrates this Doppler resolution. As shown in FIG. 7, provided that the angle of elevation can be ignored, which is the case in this application to a taxiing airplane, the radial velocity Vr of a fixed point located at the azimuth eaz with respect to the axis of the beam is written: Vr = -Va sin (eaz) (1) Where Va is the longitudinal velocity of the plane when taxiing And consequently, its Doppler frequency is written: Fd - = 2 = .` sin ((2) 20 Where A represents the wavelength Two fixed points angularly separated by an angular difference, 8.6az generate two Doppler frequencies separated by: 3 Fd = cos (ei, 9. (3) Thus, if the observation time used for calculating the Doppler Fourier transform is Te = 1 / AFd, each column of the Doppler distance matrix 65 corresponds to the output of a width sub-beam typically - (4) Set 6.e.'` ", centered on the azimuth angle eaz = arcsin -24 AF Q), where Fd is the center frequency of the filter considered 35 If we consider a point f ix located at the distance R and at the azimuth Gas of the radar, the Fourier transform on the Doppler axis makes it possible to bring a resolution in transverse distance: IR (5) 2 Va Ti CO2 for example, for: A = 3.9 mm R = 40 m Va = 10 m / sec Te = 50 ms Oaz = 0 We obtain a transverse resolution n = 15.6 cm In the choice of the waveform described above, the invention advantageously uses the the fact that the angular resolution, which results in a transverse distance resolution seen from the radar, is inversely proportional to the speed of the carrier. In the case where the observed target is animated with a radial velocity Vro with respect to the radar, the angular separation by Doppler filtering is unchanged, but because of the ambiguity angle / velocity, the direct estimate of the angle from the measurement of the Doppler frequency is biased because we obtain: F d = sin (8) and ra. d Vro = arcsin (- 2: Va where θ is the estimation of the azimuth angle obtained directly from the measurement of the Doppler frequency Fd.
    [0009] Doppler compression therefore has the main objective of providing the radar with the transverse resolution, the radial resolution being obtained by the transmitted bandwidth. The angular location must be refined by a complementary means, since the detection is concerned with both the targets (6) (7) (7) fixed and moving targets. This is done by selecting a distance-Doppler zone. FIG. 8 illustrates the selection of a Doppler-distance zone 512. In this step the radar establishes a second map of reduced dimensions with respect to the first one by selecting therein a sub-set of distance resolution and Doppler resolution cells corresponding to the possible positions of potential obstacles that could collide with the wing tip.
    [0010] As indicated above, so as to take advantage of the angular discriminator power of the Doppler axis to favor certain angular areas and to limit the computing power, a selection of a distance-Doppler zone of interest 81 is performed in this step 512. To select this zone, the processing takes into account the current speed of the carrier on a range-Doppler zone of interest, which corresponds, seen from the radar, to a distance swath and to a limited angular domain. Examples of selection criteria are described below. - Only obstacles located in relation to the fuselage at a lateral distance close to the end of the wing are likely to cause a collision, and must be taken into consideration. For example, it can be considered that the extension of the danger zone extends more or less 10 meters on either side of the end of the wing. This criterion makes it possible to delimit a minimum radar swath limiting the treatment zone on the radial distance axis, seen from the radar. - On the other hand, given the reaction times and braking distance, the minimum longitudinal detection distance from the end of the wing for a first alert level is a function of the speed of the carrier. Furthermore, radar processing requires a minimum number of successive detections to report the presence of an obstacle reliably with a very low risk of false alarm. These two constraints make it possible to determine the upper distance limit of the detection zone, seen from the end of the wing. This limit is for example of the order of 75 m for a speed Va of 10 m / sec, and of the order of 20 m for speed Va of 2.5 m / s. It makes it possible to determine the first limit of the minimum angular detection range in the horizontal plane, seen from the radar. - Finally, it is necessary to maintain a monitoring of the position of the obstacle to a minimum distance corresponding to the braking distance, to verify that it remains in the collision course. This constraint makes it possible to determine the lower distance limit of the detection zone, seen from the end of the wing. This limit is typically 55 to 10 m / sec and 10 to 2.5 m / sec. It makes it possible to determine the second limit of the minimum angular detection range in the horizontal plane, seen from the radar.
    [0011] FIGS. 9a and 9b illustrate, by way of example, minimum monitoring domains corresponding to the criteria set out above, for detection limited to fixed obstacles. These figures represent two opposite situations, FIG. 9a corresponding to a maximum speed Va of 10 m / s and FIG. 9b to a minimum speed of 2.5 m / s. In the example of FIG. 9a, the minimum detection range 91 covers an angular range of 30 ° with a minimum swath of 30 meters, oriented approximately + 45 ° with respect to the line of sight 8 and extending 10 meters on both sides of the end of the wing. The minimum lower limit of the detection range is 55 meters and the upper limit is 75 meters. In the example of FIG. 9b, the minimum detection range 92 covers an angular range of 5 ° with a minimum swath of 26 meters, oriented about -35 ° with respect to the line of sight 8 and extending 10 meters on both sides of the end of the wing. The minimum lower limit of the detection range is 10 meters and the upper limit is 20 meters. These values indicated in relation to FIGS. 9a and 9b are given by way of example and can be optimized according to the carrier and the collision scenarios envisaged. To these detection domains, defined by distance and azimuth angle limits, correspond directly for fixed obstacles, a range-limited and Doppler range on the distance-Doppler map. However, if the detection of moving obstacles is required, it is necessary to widen the Doppler domain to take into account the contribution made by the radial velocity specific to these obstacles, according to relation (6). On the other hand, if the detection of mobiles coming late into the field of view of the radar is envisaged, it is also necessary to increase the limits of the detection range angularly. Thus, according to the invention, the limits of the Doppler domain are established as a function of the speed of the carrier 10, for example according to the table below. Carrier speed Limits of the angular range to the line of sight 8 Speed domain to consider Doppler domain to consider 7.5 to 10 m / s 0 ° to 45 ° -10 m / s to 0 m / s -4 KHz at 0 KHz 5 to 7.5 m / s -35 ° at 45 ° -10 m / s at 4.3 m / s -3 KHz at 2.1 KHz 2.5 at 5 m / s -45 ° at 10 ° -5.4 m / s to 3.5 m / s -2.1 KHz to 1.7 KHz 0 to 2.5 m / s -45 ° to 0 ° -5.4 m / s to 1.8 m / s -2 KHz to 0.9 KHz The range range limits extend from 30 meters to 70 meters, regardless of the speed of the carrier 10. The next step 37 is the step of forming beams in azimuth. In this step, the radar thus establishes new distance / Doppler maps by beamforming by calculation on the subsets of distance resolution cells retained on each antenna path, so as to separate the angular observation beam in the plane. horizontal in several sub-beams, at least two.
    [0012] The processes of the preceding steps 511, 512 are performed independently on each of the four reception channels, up to this stage of beamforming by the calculation. In this step, the radar processing means focus, by coherent integration in reception, the radar beam in several different directions on the distance-Doppler maps previously constructed, a map corresponding to each reception channel. This operation can be carried out by the operator defined by the following relation (8) on each of the pixels (i, j) of the input Doppler-distance maps: S .. (9) at -15si1 eaz (8) 0 - Jr !. With: Nant: The number of receiving antennas ÔCI: The distance between each pair of elementary antennas: The wavelength 0a,: The direction in which the beam is formed j: The indices of the pixels along the Doppler axes ( i) and distance (j) s (i, j): The amplitude and phase signal in the distance / Doppler box i, j.
    [0013] For example, in the embodiment with 4 reception channels, it is possible to form the beams typically in the directions: 0 '= + 45 °, 0a, = + 15 °, 0a, = - 15 ° and 0' = + 45 °, from the four Doppler distance maps. This treatment thus delivers four distance / Doppler 81 maps of dimension 15 (NdoppSel NdistSel) in each of the aforementioned directions. Figures 10a and 10b illustrate examples of beam formations. Fig. 10a is a four-way receive embodiment where the spacing between each receiving antenna in the horizontal plane is X12. In this case, four beams 101, 102, 103, 104 are formed with a width of about 30 ° and are unambiguous. It should be noted that the diagram of the elementary receiving antennas tends to detach the formed beams. Indeed, the resulting diagram is defined by the grating directivity weighted by the elementary diagram 25 determined by the opening of the elementary subareas. Since this bias is predictable, it is possible either to take this effect into consideration as soon as the beams are formed to position them correctly, or to compensate for these biases a posteriori during the angular estimation of the detected objects. Thanks to the processing carried out by a radar according to the invention, it is also possible to improve the resolution of the reception beams including the high offsets, by spacing the reception antennas with a spacing greater than X / 2, which This is not usually possible because of the presence of ambiguities lobes which tend to make the detours located on the opposite sector show their true position relative to the axis of the antenna. This situation is presented in FIG. 10b, where 11 beams 105 appear. Indeed, for an obstacle in the collision course with the wing of the airplane, the sign of the speed corresponding to an approach to or a distance from -vis radar unambiguously allows to locate the detection of the left side or the right side relative to the axis of the antenna. For any obstacle in a collision course, the sign of the Doppler frequency thus makes it possible to remove the left / right ambiguity that could be generated by an ambiguous antenna pattern.
    [0014] Figure 11 illustrates the step of integrating the distance-Doppler map. More particularly, this step 514 performs the temporal integration of several successive distance / Doppler maps obtained on each beam formed in the preceding step, adapted to the targets in collision trajectory. An objective of this step 514 is notably to increase the signal-to-noise ratio by non-coherent temporal integration of the distance-Doppler images resulting from the preceding step, that is to say in each of the aiming directions. More particularly, FIG. 11 illustrates the principle of non-coherent integration of distance-doppler maps. The integration is performed on the two axes, Doppler and distance of each card 81, taking into account during the integration time, possible migrations in distance and Doppler, limiting the integration to temporal displacements of pixels that can correspond to collision trajectories: 25 - On the Doppler axis: Each output pixel (i, j) is obtained by non-coherent integration of Nintoopp Doppler pixels located in the same cell distance from the input card, where NintDopp is chosen depending on the maximum Doppler migration during the integration time. In other words, we set an integration time and we see how many filters can move the Doppler target. It is also possible at this level to limit the integration to only those pixels that have a predefined signal-to-noise ratio and deemed sufficient to correspond to a presumption of presence of a useful signal. - On the Time axis: All the pixels of the distance / Doppler maps resulting from the previous step are summed inconsistently over a time depth defined by an NNC parameter.
    [0015] This summation can be slippery or not. A pixel xout (i, j) at the output is thus obtained by non-coherent integration according to the following relation (9): 25: index on the Doppler axis: index on the axis distance n: index on the time axis 110 The duration of the noncoherent integration can be from 250 ms to 300 ms depending on the waveform used. The numerical values applied to the two parameters NNC and NintOop are for example the following ones - NNC = 5 (ie 250 ms of non-coherent integration); - NintDopp depends on the current waveform and evolves according to the following table: Shape Number of boxes Angular resolution Number of integration wave boxes (Rntoop) (Va function) Doppler of the map in the Doppler axis [3.ar, 'at 70m] output F00 10 [2 °, 3 °] [3m, 4m] 26 F01 8 [1.8 °, 2.7 °] [2.2m, 3.2m] 50 F02 2 [0.8 °, 1.8 °] ] 102 [1m, 2m] F03 1 [0.9 °, 4 °] [1m, 5.4m] 88 In a very high resolution case corresponding to the last line of the first column, we obtain Niotoopp = 1, because it does not There is no Doppler migration possible, the target can not change the Doppler filter. In the first row of the third column, we obtain a number of Doppler boxes equal to 26, related to the angular resolution (here between 2 ° and 3 °) and corresponding to the resolution. A filter corresponds to a given direction. In this case, there are 26 filters of interest for an angular resolution between 2 ° and 3 °. At the end of this treatment, a Doppler-distance map 111 is available for each aiming direction, corresponding to each beam formed. The following steps 52, 53, 54 consist in detecting then characterizing the objects present in the instrumented domain, in distance, in speed and in angular position. The first of these steps is to detect in each of the formed beams the presence of a possible target. The detection is carried out in a conventional manner, by comparing each pixel with respect to the noise, possibly supplemented by the validation of a criterion of contrast with the neighboring pixels or of detections of contours on the Doppler 111 distance maps resulting from the previous treatments. . This operation is performed for each formed beam. The estimation of the speed and the location of the useful targets is done conventionally according to the following steps: For each pixel that has given rise to detection, indices i, j, according to FIG. composite frequency Doppler distance, Fdist Extraction of the index i of the pixel that has given rise to detection to identify the center frequency of the distance cell 121, and refining of the measurement by contrast estimation with the adjacent pixels 30 on the distance axis - Estimation of the Doppler Frequency, Fdop Extraction of the Detected Pixel Index j to Identify the Center Frequency of the Distance Cell 121, and Refinement of the Contrast Estimate Measurement with the Adjacent Doppler Pixels 3013 84 9 19 - Estimation of the radial distance Drad according to the following relation (10): Drad = G CL1Trn 221Fm where: 5 - ATm is the duration of the ramp of the waveform of index m; AF 'is the modulation band of the ramp of index m. In the example of the four waveforms in Figure 4 which will be detailed in the appendix, m varies from 0 to 4, with: - ATo = 96 ps, ATi = 126 ps, 672 = 178 ps and 373 = 388 ps , and - AF0 = 50 MHz, 3, F1 = 65 MHz, LFm = 50 MHz, zF2 = 100 MHz and AF3 = 200 MHz. Radial distance echoes are re-calibrated and the Doppler bias is corrected, hence the term distance and Doppler composite frequency.
    [0016] In the example of FIG. 4, there are four waveforms F00, F01, F02 and F03, m varying here from 0 to 3. - Estimation of the azimuth angle Advantageously, the estimation of the Angle of azimuth is performed for each detected pixel by comparing the level received on the distance / Doppler maps of two adjacent formed beams, for example according to a known monopulse amplitude operator.
    [0017] The detection and location step 52 is for example followed by a tracking step 53. The tracking is performed by a known processing in the 131 mark of the radar. The targets are tracked so as to consolidate the detections, to refine their measurements of position and velocities obtained, and to estimate their trajectories.
    [0018] In a following step 54 a change of reference is made, passing from the reference 131 linked to the radar to the reference 132 linked to the end of the wing of the aircraft as shown in FIG. 13. This reference change is made from position the potential obstacles relative to the end of the wing. At this stage, only the detections in the collision course are for example retained. The tracks positioned in this new marker can then be exploited by the collision avoidance system to be viewed and / or allow the decision making of pre-alert or emergency alert. The invention has been described for anticollision with respect to the ends of the wings of an aircraft when taxiing. It also applies to any other part of the aircraft provided that it is facing the radar. Finally, the invention can also be applied to a rolling machine, other than an aircraft. In particular, it can be applied advantageously to large-scale rolling gear to avoid colliding with various potential obstacles.
    [0019] 10 3 0 13 84 9 21 Appendix This appendix provides an example of a waveform selection guide of Figure 4. FO waveform a - ohé ue - va Va ns between 7.5 and 10 m / s AF = 50 MHz to obtain 3m resolution; AFdopp = 8KHz considering the whole beam (100 °); Fr = 1.3 AFdopp = 10.2KHz (Tr = 98e) to respect the constraint Frec> AFdopp; AT = Tr = 2 = 96. loop stabilization rest time Fech = 625KHz (Teoh = 1.6gs), the maximum sampling frequency of the radar; In this case, the ambiguity distance is 90m. Speed domain at -3dB (100 °): -7.7m / s, 7.7m / s Angular resolution: [0.22 °, 029 °] with = 2o.res: r, and Te = 50ms Or a transversal resolution at 70m from [ 0.27m, 0.35m] Waveform FOLp_ota- between 5 and 7.5 m / s AF = 65 MHz to obtain 2.3m resolution; AFdopp = 6KHz considering the whole beam (100 °); 25 Fr = 1.3 AFdopp = 7.6 KHz (Tr = 128 μs) to respect the constraint Frec> AFdopp; AT = Tr-2pS = 126 kts; loop stabilization rest time; Fech = 625KHz (Teoh = 1.4S), the maximum sampling frequency of the radar; In this case, the ambiguity distance is located at 90m. Speed domain at -3dB (100 °): -5.7m / s, 5.7m / s Angular resolution: [0.29 °, 0.44 °] That is a transverse resolution at 70m of [0.35m, 0.53m] 35 Waveform F00 for UDF between 2.5 and 5 m / s AF = 100 MHz to obtain 1.5m resolution; Afdopp = 4KHz considering the whole beam (100 °); Fr = 1.3 at Fdopp = 5.5 KHz (Tr = 180p, $) to respect the constraint Frec> AFdopp; AT = Tr - 2FIS = 178 ps; loop stabilization rest time; Fech = 625KHz (Tech = 1.611s), the maximum sampling frequency of the radar; In this case, the ambiguity distance is 83 m. Speed domain at -3dB (100 °): -4.2, +4.2 m / s Angular resolution: [0.4 °, 0.91 = transverse resolution at 70m from [0.5m, 1.1m] FAI waveform: for Va less than 2.5 m / s OF = 200 MHz to obtain 0.75m resolution; AFdopp = 2KHz considering the whole beam (100 °); Fr = 1.3 AFdopp = 2.56 KHz (Tr = 1951-1S) to respect the constraint Frec> AFdopp; AT = Tr-21.1s = 388 ps; loop stabilization rest time; Fech = 625KHz (Tech = 1.6ps), the maximum sampling frequency of the radar; In this case, the ambiguity distance is located at 90 m. Speed domain at -3 dB (100 °): -2, +2 m / s Angular resolution: [0.90 °, 5 °] That is a transverse resolution at 70 m from [ 1.1m, 6.1m] 30
    权利要求:
    Claims (16)
    [0001]
    REVENDICATIONS1. Anti-collision radar for rolling vehicle, characterized in that it is able to be fixed laterally on the fuselage of a machine (10) and to realize the detection of obstacles in the collision course with a part (5, 6) of the gear against said radar (1,
    [0002]
    2), it comprises at least one antenna transmission line 5 (31) emitting a wave of the FMCW type and several antenna receiving channels (320, 321, 322, 323) arranged in the same plane, the shape (F00, F01 , F02 and F03) of said wave and the range of angular coverage of said radar being a function of the speed of the vehicle, the processing means of said radar performing at least the following steps 10 to achieve said obstacle detection in collision course Establishment (511) in the radar reference (1, 2) of a first distance / Doppler map (65) for separating echoes according to distance and Doppler resolution cells on said plurality of antenna receiving channels; Establishing (512) a second distance / Doppler map (81) of reduced dimensions relative to the first (65), by selecting in the latter a subset of distance and Doppler resolution cells corresponding to the possible positions of targets capable of colliding with said part (5, 6) the machine, said selection being a function of the speed of the vehicle; Establishment (37) of new distance-doppler Doppler maps by computation on the subsets of distance resolution cells retained on each receiving antennal path, so as to separate the angular observation beam in the plane of the channels Antennas in at least two beams (101, 102, 103, 104, 105); Time integration (514), on each formed beam, of several successive distance / Doppler maps obtained in the preceding step (37) in order to obtain a final distance / Doppler map (111) for each beam, the integration time being function of the waveform used; These steps being followed by at least one detection step (52) in each of the beams formed from said final distance / Doppler map (111) .2. Radar according to claim 1, characterized in that in the detection step (52), the estimation of the azimuth angle of said target is performed, for each pixel detected in the final distance / Doppler map (111) by comparing the received level on the distance / Doppler maps of two adjacent formed beams according to an amplitude monopulse operator.
    [0003]
    3. Radar according to any one of the preceding claims, characterized in that the detection step (52) is followed by a step of tracking targets detected in the reference (131) of said radar. 10
    [0004]
    4. Radar according to any one of the preceding claims, characterized in that it performs a step (54) of change of geographical reference, passing from the reference (131) linked to the radar to a reference (132) linked to said part ( 5, 6) of the machine (10), for estimating the coordinates of the targets in the reference (132) 15 linked to said part.
    [0005]
    5. Radar according to any one of the preceding claims, characterized in that the plane of the antennal receiving channels (320, 321, 322, 323) is horizontal. 20
    [0006]
    6. Radar according to any one of the preceding claims, characterized in that the beam formation is performed over an angular range (3, 4) of +/- 45 ° in the plane of the antenna channels, with respect to an axis of target (8, 9), adapted to be perpendicular to the axis of the fuselage of the machine (10).
    [0007]
    7. Radar according to any one of the preceding claims, characterized in that the antennas of the antennal reception channels (320, 321, 322, 323) on which the beam formation by calculation (37) 30 is made are spaced apart. of the other more than half a wavelength, the ambiguity of the angular position of a target being raised by the Doppler frequency of the distance / Doppler cell of said target.
    [0008]
    8. Radar according to any one of the preceding claims, characterized in that the first distance / Doppler map (65) is obtained after distance compression and Doppler compression of said FMCW type wave.
    [0009]
    9. Radar according to any one of the preceding claims, characterized in that it comprises four antennal receiving channels (320, 321, 322, 323).
    [0010]
    10. Radar according to any one of the preceding claims, characterized in that said wave is in the millimeter range. 10
    [0011]
    11. Radar according to claim 10, characterized in that said wave is in the frequency band 76 to 77 GHz.
    [0012]
    Radar according to any one of the preceding claims, characterized in that the machine is an aircraft.
    [0013]
    13. Radar according to claim 12, characterized in that said portion (5, 6) is a wingtip of the aircraft. 20
    [0014]
    14. anticollision system for aircraft rolling, characterized in that it comprises at least two radars (1, 2) according to any one of the preceding claims, installed laterally each side of the fuselage. 25
    [0015]
    15. Anti-collision system according to claim 14, characterized in that each radar (1, 2) is installed in front of the wing.
    [0016]
    Anti-collision system according to claim 15, characterized in that each radar (1, 2) is fixed at the location of a porthole in the vicinity of the cockpit.
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    同族专利:
    公开号 | 公开日
    EP3074786B1|2020-04-15|
    EP3074786A1|2016-10-05|
    US20160259048A1|2016-09-08|
    WO2015078682A1|2015-06-04|
    FR3013849B1|2015-11-27|
    US10585186B2|2020-03-10|
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    法律状态:
    2015-10-23| PLFP| Fee payment|Year of fee payment: 3 |
    2016-10-28| PLFP| Fee payment|Year of fee payment: 4 |
    2017-10-26| PLFP| Fee payment|Year of fee payment: 5 |
    2018-10-26| PLFP| Fee payment|Year of fee payment: 6 |
    2019-10-29| PLFP| Fee payment|Year of fee payment: 7 |
    2020-10-26| PLFP| Fee payment|Year of fee payment: 8 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1302731A|FR3013849B1|2013-11-26|2013-11-26|RADAR ANTICOLLISION, IN PARTICULAR FOR AN AIRCRAFT FOR ROLLING AND ANTICOLLISION SYSTEM|FR1302731A| FR3013849B1|2013-11-26|2013-11-26|RADAR ANTICOLLISION, IN PARTICULAR FOR AN AIRCRAFT FOR ROLLING AND ANTICOLLISION SYSTEM|
    US15/034,371| US10585186B2|2013-11-26|2014-11-07|Anticollision radar, especially for an aircraft when taxiing, and anticollision system|
    EP14799380.2A| EP3074786B1|2013-11-26|2014-11-07|Anticollision radar, especially for an aircraft when taxiing, and anticollision system|
    PCT/EP2014/074056| WO2015078682A1|2013-11-26|2014-11-07|Anticollision radar, especially for an aircraft when taxiing, and anticollision system|
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