• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The imaging assembly comprises: - a multiband sensor (5), comprising a plurality of light sensors (7) each for measuring a light intensity reflected by a target (8) in a predetermined frequency band, sunshine (9) having a plurality of control sensors each for measuring an ambient light intensity in one of the predetermined frequency bands of the multiband sensor (5) each associated with a bandpass filter; an electronic module (13) configured to calculate at least one characteristic quantity of the light intensity returned by the target (8) in each predetermined frequency band; the sun detector (9) comprising a housing (21), the control sensors being fixed to the housing (21), the band-pass filters (17) being fixed to the housing (21) each facing the photosensitive surface of the sensor associated witness.
    公开号:FR3052556A1
    申请号:FR1655459
    申请日:2016-06-13
    公开日:2017-12-15
    发明作者:Antoine Beyeler；Eng Hong Sron
    申请人:Parrot Drones SAS；
    IPC主号:
    专利说明:

    The invention relates generally to imaging assemblies embedded on drones, in particular for agriculture.
    More precisely, the invention relates, according to a first aspect, to an imagery assembly intended to be embedded on a drone. US 2014/0022381 discloses an imaging assembly with a multiband sensor for measuring light intensity in a plurality of predetermined frequency bands, and a sun detector for measuring the level of ambient light intensity in the same predetermined frequency bands.
    The sun detector includes an image taking apparatus with a matrix photosensitive screen integrated in the multiband sensor. The sun detector further includes a plurality of optical fibers and bandpass fibers. Each bandpass fiber is associated with the end of an optical fiber and filters the light radiation captured by the optical fiber. The optical fiber directs the captured light to a matrix photosensitive screen area.
    Such a set is complex and fragile. In particular, the radius of curvature of the optical fibers must be mastered and known.
    In this context, the invention aims to provide a set that is simpler and more reliable. To this end, the invention relates to an imaging assembly for a drone, the assembly comprising: a multiband sensor, comprising a plurality of light sensors for each measuring a light intensity reflected by a target in a predetermined frequency band , the frequency bands associated with the different light sensors being different from each other, - a sun detector, comprising a plurality of control sensors for each measuring an ambient light intensity in one of the predetermined frequency bands of the multiband sensor, the sunshine detector comprising for each control sensor a bandpass filter configured so that an incident light ray in the associated frequency band arrives at a photosensitive surface of said control sensor and a light beam incident outside the frequency band associated does not arrive at the photosensitive surface of said sensor temo in; an electronic module configured to calculate at least one characteristic quantity of the light intensity reflected by the target in each predetermined frequency band, by using the light intensities returned by the target in said predetermined frequency bands measured by the multiband sensor and the ambient light intensities in said predetermined frequency bands measured by the sun detector, the sun detector comprising a housing, the control sensors being fixed to the housing, the bandpass filters being fixed to the housing each facing the photosensitive surface the associated control sensor. The assembly may also have one or more of the following characteristics, considered individually or in any technically possible combination: - the multiband sensor comprises another independent housing and separated from the housing of the sunshine detector, the light sensors being fixed to another housing; the sun detector comprises a light diffuser fixed to the housing opposite the band-pass filters, so that the incident light rays pass through the light diffuser before reaching the band-pass filters; the sun detector comprises, for each control sensor, a convergent lens arranged opposite the corresponding bandpass filter and interposed between the light diffuser and said bandpass filter; the sun detector comprises a single convergent lens arranged opposite all the band-pass filters and interposed between the light diffuser and said band-pass filters; the sun detector comprises, for each control sensor, a screen arranged opposite the associated bandpass filter and interposed between the light diffuser and said band-pass filter, the screen having a conical aperture converging from the diffuser to said bandpass filter; and the sun detector comprises a plate and a support fixed on the plate and delimiting a plurality of wells, the control sensors being mounted on the plate each at the bottom of one of the wells, the bandpass filters being mounted in the wells; well above the control sensors.
    According to a second aspect, the invention relates to a system comprising a flying drone and an imaging assembly having the above characteristics, mounted on the drone. In addition, the system may have the following characteristics: the drone comprises a body having upper and lower surfaces intended to be turned upwards and downwards respectively when the drone is hovering, the multiband sensor being fixed to the lower surface and the sun detector being fixed to the upper surface.
    According to a third aspect, the invention relates to a method for calculating at least one characteristic quantity of the light intensity reflected by a target in a plurality of predetermined frequency bands, the method comprising the following steps: - overflight of the target using a system comprising a flying drone and an imaging unit; during the overflight, measurement by the imaging unit, at a plurality of successive instants, of the light intensity returned by the target in each of said predetermined frequency bands; during the overflight, measurement by the imaging unit, at a plurality of successive instants, of the ambient light intensity in each of said predetermined frequency bands, and simultaneously recording of a parameter characterizing the orientation of the detector; sunshine compared to the sun; calculating the characteristic magnitude of the luminous intensity returned by the target in each predetermined frequency band using the light intensities returned by the target in said pre-measured predetermined frequency bands and the ambient light intensities in said predetermined predetermined frequency bands measured; the calculation step comprising: - a substep of determining the orientation of the target with respect to the sun; a sub-step of calculating the total light intensity received by the target in one of the frequency bands, using only the ambient light intensities in said frequency band measured when a difference between the orientation of the sun detector relative to in the sun and the orientation of the target with respect to the sun is less than a predetermined value. Other features and advantages of the invention will emerge from the detailed description given below, by way of indication and in no way limiting, with reference to the appended figures, among which: FIG. 1 is a simplified schematic representation of a flying drone equipped with an imaging unit according to the invention; FIG. 2 is a schematic representation illustrating the operation of the imaging assembly of FIG. 1; FIG. 3 is a graph indicating the reflectance levels of a type of agricultural crop determined as a function of the wavelength of the light, and the frequency bands measured by the imaging assembly of FIG. 1; FIGS. 4 to 7 illustrate various embodiments of the sun detector of the imaging assembly of FIG. 1; and - Figure 8 schematically illustrates different angles considered in the method of the invention.
    As can be seen in FIG. 1, the imaging unit 1 is intended to be embarked on a drone, and more specifically on a flying drone 3. It is intended to be used in the field of agriculture, typically to monitor the crop growth.
    As can be seen in FIGS. 1 and 2, the assembly 1 comprises: a multiband sensor 5, comprising a plurality of light sensors 7 for each measuring the light intensity returned by a target 8 in a predetermined frequency band; a sun detector 9, comprising a plurality of control sensors 11 (FIGS. 4 to 7) for each measuring an ambient light intensity in one of the predetermined frequency bands of the multiband sensor 5; an electronic module 13, configured to calculate at least one characteristic quantity of the light intensity reflected by the target 8 in each predetermined frequency band, by using the light intensities returned by the target 8 in said predetermined frequency bands measured by the multiband sensor 5, and the ambient light intensities in said predetermined frequency bands measured by the sun detector 9.
    Target 8, for applications in the field of agriculture, typically corresponds to a crop, for example a field of corn, wheat or any other type of crop. The multiband sensor 5 measures the intensity of the light reflected by the crops in the predetermined frequency bands.
    The frequency bands associated with the different light sensors 7 are different from each other. They are chosen according to the application considered.
    In a typical example, the multiband sensor 5 comprises four light sensors 7, provided as illustrated in FIG. 3 for measuring the light intensity in a frequency band V corresponding to the green color in the visible spectrum, in a frequency band R corresponding to the red color in the visible spectrum, in a frequency band BR located in the infrared frequency range immediately near the visible spectrum, and an IFP frequency band corresponding to the near infrared.
    For example, the V band is centered on a wavelength of 550 nanometers and has a width of 40 nanometers, the band R is centered on a wavelength of 660 nanometers and has a width of 40 nanometers, the band BR is centered on a wavelength of 735 nanometers and has a width of 10 nanometers, and the IRP band is centered on a wavelength of 790 nanometers and has a width of 40 nanometers.
    Plant reflectance, that is, the percentage of incident light intensity reflected by the plant for each wavelength, varies with the state of the plant. In FIG. 3, the curve VV represents the reflectance of a healthy plant, as a function of the wavelength. The curve VS represents the reflectance of a stressed plant as a function of the wavelength. Curve S shows the reflectance of the soil as a function of the wavelength.
    It can be seen that, for both the VV curve and the VS curve, the reflectance in the visible spectrum is maximum for the V frequency band.
    The difference in reflectance between healthy plants and stressed plants is greater in the frequency band R than in the frequency band V. The band BR corresponds to a zone of the spectrum where the reflectance increases sharply, as well for healthy plants only for stressed plants.
    In the field of near infrared, that is to say for the IRP band, there is a very significant difference in reflectance between healthy plants and stressed plants.
    Thus, it is well understood that the light intensity data returned by the target, which is a crop in the agricultural field, for the various predetermined frequency bands, provide information on the state of the crop. These data show in particular whether the crop is under stress or not.
    This stress can be water stress, the plant being underfed in water. Stress can also be due to the attack of a microorganism, a parasite or other. The light intensity measured by the multiband sensor 5 is a function of the ambient sunlight. The sun sensor 9 is therefore provided to correct the light intensity values measured by the multiband sensor 5, depending on the ambient light intensity.
    This correction is performed by the electronic module 13.
    The electronic module 13 is for example integrated in the multiband sensor 5. Alternatively, it can be embedded on the drone, or be located in a remote information processing unit. The module 13 is for example a calculator or a set of programmable logic components or a set of dedicated integrated circuits.
    For example, the light intensity returned by the target 8 in a predetermined frequency band measured by the multiband sensor 5 is corrected proportionally to the ambient light intensity in the same predetermined frequency band measured by the sun detector 9.
    Alternatively, the correction made is calculated in another way. These corrections are of known type and will not be detailed here.
    The characteristic quantity calculated by the electronic module 13 is for example the luminous intensity returned by the target 8 in the predetermined frequency band corrected according to the measurements of the sun detector 9, or corresponds to the reflectance of the target 8 in the predetermined frequency band, or any other relevant quantity.
    Typically, the multiband sensor 5 comprises, in addition to light sensors 7, an RGB camera 15, for taking images in the visible spectrum of the target 8, typically crops.
    The multiband sensor 5 typically comprises a remote communication module 16 by wave, for example of the wifi type.
    Each light sensor 7 is typically an image pickup apparatus, such as a camera having a resolution of 1.2 megapixels for example.
    The multiband sensor 5 typically comprises for each light sensor 7 a not shown bandpass filter, configured to filter incident light rays and pass only those in the frequency band associated with the light sensor 7.
    The control sensors 11 of the sun detector 9 are for example photodiodes. Such diodes transform light radiation into an electrical signal.
    The control sensors 11 are provided for each measuring the ambient light intensity in one of the predetermined frequency bands of the multiband sensor 5, as indicated above. The control sensors 11 measure the ambient light intensity in different frequency bands from each other. Thus, there is the same number of control sensors 11 as light sensors 7.
    In order to filter the incident light rays, the sun sensor 9 comprises, for each indicator sensor 11, a band-pass filter 17 (FIGS. 4 to 7), configured so that an incident light beam in the frequency band associated with the control sensor 11 can arrive at the photosensitive surface 19 of the control sensor, and that an incident light ray outside the associated frequency band does not arrive at the photosensitive surface 19 of the control sensor 11.
    As can be seen in particular in FIGS. 2 and 4, the sun detector 9 comprises a housing 21, the control sensors 11 and the bandpass filters 17 being fixed to said housing. It can be seen in FIG. 4 that the bandpass filters 17 are each fixed facing the photosensitive surface 19 of the associated control sensor 11.
    More specifically, the sun detector 9 comprises a plate 23 and a support 25 fixed to the plate 23. The plate 23 and the support 25 are typically fixed inside the housing 21.
    The control sensors 11 are mounted on the plate 23. The plate is typically a printed circuit board (PCB in English: Printed Circuit Board >>).
    The support 25 delimits a plurality of wells 27, the control sensors 11 being disposed at the bottom of each well. The wells 27 are closed at one end by the plate 23 and are open at the opposite end.
    For a sun detector 9 comprising four control sensors 11, the wells are arranged for example on the corners of a square.
    The bandpass filters 17 are mounted in the wells 27, above the control sensors 11.
    More specifically, each filter 17 is mounted such that the photosensitive surface 19 of the associated control sensor 11 is opposite the band-pass filter 17 along the central axis of the well 27.
    In the embodiment of FIG. 4, the sun detector 9 comprises a light diffuser 29, fixed to the housing 21 opposite the bandpass filters 17. Thus, the incident light rays pass through the diffuser of the light diffuser 29. light 29 before reaching the bandpass filters.
    The light diffuser 29 is for example substantially parallel to the band-pass filters 17 and located slightly at a distance, above the band-pass filters 17. It is located above the support 25. Typically, it is fixed in a window 31 formed on the housing 21 (Figure 2), vis-à-vis the support 25
    The diffuser 29 makes it possible to obtain an excellent correction of the light intensity measured by the multiband sensor 5. Indeed, the control sensors 11 must be representative of the operation of a plant. It is known that a plant integrates the light energy differently depending on the angle of incidence of the light rays. The rays shaving the surface of the plant are not absorbed by it. The diffuser 29 is configured such that the incident light rays RI forming with the normal N to the diffuser an angle of incidence close to 90 "are reflected almost entirely.
    Incident light rays forming with the normal N a lower angle of incidence, are reflected by the diffuser 29 in a much smaller proportion.
    The diffuser 29 is a plate of a material chosen to diffuse virtually all incident light flux, without absorption. Part of the incident light flux is reflected, and another part transmitted through the diffuser 29. The transmitted light flux has a substantially identical luminance in all directions, regardless of the orientation of the luminous flux. The diffuser is substantially flat, in order to have a cosine response depending on the incident angle.
    The diffuser 29 is for example Makrolon 2407 020080.
    As shown in Figure 1 and Figure 2, the multiband sensor 5 comprises another housing 33 independent and separate from the housing 21 of the sun detector.
    The light sensors 7 are mounted on said other housing 33.
    The housings 21 and 33 can thus be mounted independently on the drone 3. They are not connected to each other by an optical fiber. They communicate with each other by waves, or by means of a cable 35 making it possible to transfer the data measured by the sunshine detector 9 to the multiband sensor 5.
    These data are directly exploited by the electronic module 13. If the electronic module 13 is remotely deported, the data measured by the multiband sensor 9 are for example transferred to the electronic module 13 by the remote communication module 16 fitted to the multiband sensor 5. .
    Thus, in the invention, the sun detector is an independent unit, independent of the multiband sensor. It is not necessary to use optical fibers to bring the light to a photosensitive member integrated in the multiband sensor.
    A second embodiment of the invention will now be described, with reference to FIG. 5. Only the points by which the second embodiment differs from the first will be described below. The identical elements or providing the same functions will be designated by the same references in both embodiments.
    In the embodiment of FIG. 5, the sun sensor 5 comprises, for each control sensor 11, a convergent lens 35 disposed opposite the corresponding band-pass filter 17. The lens 35 is interposed between the light diffuser 29 and the band-pass filter 17.
    Typically, the convergent lens 35 is disposed at the entrance of the well 27 in which the band-pass filter 17 is arranged.
    It is mounted for example with a convex face 37 facing the diffuser 29 and a flat face 39 facing the band-pass filter 17. The use of the lenses makes it possible to improve the reliability of the measurement. the ambient light intensity in the predetermined frequency bands.
    Indeed, the diffuser 29 has an angular response, in the sense that for an incident light beam having a given angle of incidence at the level of the diffuser 29, the transmitted ray will leave the diffuser 29 forming an angle with the normal N which is a function the wavelength of the incident ray. The diffuser 29 behaves as a diffuse source at the output, that is to say towards the control sensors 11.
    Moreover, the bandpass filters used are of the interferometric type. They have the advantage of having very steep cut-off slopes. On the other hand, due to the presence of the diffuser, these bandpass filters let part of the energy in the infrared, and have a bandwidth shifted towards blue.
    This phenomenon is particularly marked for a bandpass filter 17 centered on the green color of the visible spectrum. The addition of a convergent lens 35 makes it possible to correct this phenomenon.
    Indeed, the light rays transmitted through the diffuser 29 are parallelized by the convergent lens 35, like the optical system of a camera.
    A third embodiment will now be described with reference to FIG. 6. Only the points by which the third embodiment differs from the second embodiment will be detailed below. The identical elements or ensuring the same function will be designated by the same references in both embodiments.
    The embodiment of Figure 6 aims to solve the same problems as that of Figure 5, namely the bias introduced by the diffuser 29 for ambient light intensity measurements.
    In the embodiment of FIG. 6, the convergent lenses 35, each dedicated to a control sensor 11, are replaced by a single convergent lens 41, arranged opposite all the band-pass filters 17, and interposed between the diffuser 29 and bandpass filters 17.
    The single convergent lens 41 covers the four wells 27. It is fixed to the support 25. For example, it has a convex face 43 facing the diffuser 29 and a flat face 45 facing the band-pass filters 17.
    A fourth embodiment of the invention will now be described with reference to FIG. 7. Only the points by which this fourth embodiment differs from the second embodiment will be detailed below. The identical elements or ensuring the same function will be designated by the same references in both embodiments.
    The fourth embodiment aims to overcome the same problems as the second embodiment, namely the bias introduced by the diffuser in the sun sensor measurements.
    As can be seen in FIG. 7, each convex lens 35 is replaced by a screen 47 disposed opposite the band-pass filter 17 and interposed between the light diffuser 29 and said band-pass filter 17. The screen 47 is opaque. It is pierced by a conical orifice 49, convergent from the diffuser 29 to the bandpass filter 17. The conical orifice 49 has an axis substantially perpendicular to the diffuser 29. The widest end of the orifice 49 is pressed against the diffuser 29. The narrowed end 53 of the orifice 49 is pressed against the band-pass filter 17. It is located, along the central axis of the cone, opposite the photosensitive surface 19 of the control sensor.
    Thus, as shown in Figure 7, only the light rays leaving the diffuser 29 in a direction substantially normal to said diffuser 29 reach the bandpass filter 17 and possibly the detector 11. The light rays leaving the diffuser 29 in a direction that 'deviate from the normal are reflected by the surface of the conical orifice and returned. They do not reach the bandpass filter 17. The opening angle of the cone is chosen according to the desired effect.
    For example, all the light rays coming out of the diffuser 29 with an angle greater than a predetermined value with respect to the normal are returned, this value being for example of the order of 12 °.
    The defects described above, namely the blue shift of the bandwidth and passing part of the energy in the infrared, are removed.
    Advantageously, the imaging unit 1 is equipped with an orientation sensor, for example an inertial unit, which makes it possible at all times to determine the orientation of the detector 9 with respect to a reference direction, the magnetic north by example.
    In this case, the electronic module 13 is preferably configured to implement the calculation method which will be described below.
    As can be seen in FIG. 1, the drone 3 comprises, for example, a body 55, a propeller 57 with a propeller at the rear of the body 55, and two wings 59. In a variant, the drone is a quadrocopter.
    Typically, the multiband sensor 5 and the sunshine detector 9 are mounted on the drone so that the multiband sensor 5 is turned down and the sunshine detector 9 is turned upward when the drone 3 is in flight. stationary.
    In the example shown, the body 55 of the drone has lower upper surfaces 61, 63 intended to be turned upwards and downwards respectively when the drone 3 is hovering.
    The sun detector 9 is fixed to the upper surface 61, preferably directly on the upper surface 61. This orientation is favorable for measuring the ambient light intensity.
    The multiband sensor 5 is fixed to the lower surface, either directly or via a clamp such as the clamp 65 of FIG.
    The multiband sensor can still be attached to a front end of the body by means of the clip 65.
    According to yet another aspect, the invention relates to a method for calculating the characteristic quantity of the light intensity returned by the target in the plurality of predetermined frequency bands.
    This method comprises the following steps: - flying over the target 8 using a system comprising the flying drone 3 and an imaging assembly 1, mounted on the drone 3; during the overflight, measurement by the imaging unit 1, at a plurality of successive instants, of the light intensity returned by the target 8 in each of said predetermined frequency bands; during the overflight, measurement by the imaging unit 1, at a plurality of successive instants, of the ambient light intensity in each of said predetermined frequency bands, and simultaneously recording of a parameter characterizing the orientation of the detector sunshine 9 with respect to the sun S; calculating the characteristic quantity of the light intensity reflected by the target 8 in each predetermined frequency band by using the light intensities returned by the target 8 in the predetermined predetermined frequency bands and the ambient light intensities in said frequency bands previously measured. The imaging unit 1 is advantageously of the type described above. Alternatively, it is different. The light intensity returned by the target 8 in each of said predetermined frequency bands is for example measured using the multiband sensor 5 described above. The ambient light intensity in each of said predetermined frequency bands is measured for example using the sun detector 9 described above.
    The characteristic quantity calculated is, for example, the luminous intensity returned by the target 8 in the predetermined frequency band corrected as a function of the ambient light intensity measurements, or corresponds to the reflectance of the target 8 in the predetermined frequency band, or is any other relevant quantity.
    For the recording of the parameter characterizing the orientation of the sun detector 9 with respect to the sun S, the imaging unit 1 is equipped with an orientation sensor, for example an inertial unit, permitting at all times to determine the orientation of the detector 9 relative to a reference direction, the magnetic north for example. The orientation of the sun detector 9 with respect to the sun S is determined, for example, by first calculating the orientation of the sun relative to the reference direction at the geographical point and at the time when the measurement is made. Then, the orientation of the sun detector 9 with respect to the sun S is determined by using the orientation of the detector 9 with respect to a reference direction and the orientation of the sun with respect to the reference direction. The calculation step comprises a sub-step ILT for calculating the total light intensity received by the target 8 in at least one of the frequency bands, based on the ambient light intensity measured in the or each frequency band. This value is for example compared to that determined directly by the multiband sensor 5 and corrects the value obtained by the multiband sensor.
    To do this, the following equation (1) is advantageously used:
    Esun.eff = Ss Esun.obj dA = (I-Io) / (Ts Ks gs) (c COS β + (1-ε)) / (ε cos κ -i- (1-ε)) (1) where
    Esun.eff is the total light intensity received by the target 8 in the frequency band;
    Ss is the spectral sensitivity of the sun detector for the frequency band; Esun.obj is the luminous intensity received by the target 8 in the frequency λ; I is the intensity measured by the sun detector for the frequency band; lo is the intensity measured by the sun detector for the frequency band in the absence of light;
    Kgest the gain of the sun detector;
    Ts is the exposure time; gs is the sensitivity of the sun detector. ε is a parameter obtained by the following equation (2): ε = Ed / (Ed + Es) (2) where Ed is directly direct and Es the diffused illumination. Direct illumination is the intensity of light coming directly from the sun to the target. The scattered illumination corresponds to the scattered light intensity, arriving on the target from all directions.
    Here we mean by total light intensity received by the target 8 in the frequency band, the integral of the light intensity received for all the frequencies of the frequency band.
    The angles β and κ are shown in FIG. 8. The angle κ typically corresponds to the angle between the direction of the sun S seen from the sun detector 9 and the normal to the sun detector 9. The angle β corresponds to typically at the angle between the direction of the sun S seen from the target 8 and the normal to the target 8.
    For a horizontal surface, the angle β corresponds to 90 ° -y, where y is the altitude of the sun seen from the observer O (see the left part of Figure 8). The calculation step comprises a substep DOB for determining the orientation of the target 8 with respect to the sun S. This substep is performed for example by image analysis, from photographs of the target 8 taken during the flyover. These photos are taken for example by the RGB 15 camera.
    This sub-step DOB therefore makes it possible to determine the angle β. This value is used in the substep ILT, in equation (1).
    The parameter ε is known only with a large margin of error. To simplify the calculations using equation (1), only the ambient light intensities in the frequency band measured when a difference between the orientation of the sun detector 9 with respect in the sun S and the orientation of the target 8 with respect to the sun S is less than a predetermined value.
    In other words, only the ambient luminous intensities measured at times when the angles β and κ are close to each other are used. In this case, the term (ε cos β + (1-ε)) / (ε cos κ + (1-ε)) of equation (1) is close to 1, so that Esun.eff is independent of ε.
    The predetermined value mentioned above corresponds for example to a difference between the angles β and κ less than 20 °, preferably less than 10 °, more preferably less than 2 °.
    权利要求:
    Claims (10)
    [1" id="c-fr-0001]
    1. - imaging unit for drone, the assembly (1) comprising: - a multiband sensor (5), comprising a plurality of light sensors (7) for each measuring a light intensity reflected by a target (8) in a predetermined frequency band, the frequency bands associated with the different light sensors (17) being different from each other, - a sun detector (9), comprising a plurality of control sensors (11) for each measuring an intensity ambient light in one of the predetermined frequency bands of the multiband sensor (5), the sun detector (9) comprising for each control sensor (11) a bandpass filter (17) configured for a light ray incident in the associated frequency band arrives at a photosensitive surface (19) of said control sensor (11) and that a light beam incident outside the associated frequency band does not reach the photosensitive surface ble (19) of said control sensor (11); an electronic module (13) configured to calculate at least one characteristic quantity of the light intensity reflected by the target (8) in each predetermined frequency band, by using the light intensities returned by the target (8) in said bands of predetermined frequencies measured by the multiband sensor (5) and the ambient light intensities in said predetermined frequency bands measured by the sun detector (9); the sun detector (9) comprising a housing (21), the control sensors (11) being fixed to the housing (21), the bandpass filters (17) being fixed to the housing (21) each facing the surface photosensitive (19) of the associated control sensor (11).
    [2" id="c-fr-0002]
    2. - An assembly according to claim 1, characterized in that the multiband sensor (5) comprises another housing (33) independent and separate from the housing (21) of the sun detector (9), the light sensors (7). being attached to said other housing (33).
    [3" id="c-fr-0003]
    3. - assembly according to claim 1 or 2, characterized in that the sunshine detector (9) comprises a light diffuser (29), fixed to the housing (21) vis-à-vis the band-pass filters ( 17), so that the incident light rays pass through the light diffuser (29) before reaching the band-pass filters (17).
    [4" id="c-fr-0004]
    4. An assembly according to claim 3, characterized in that the sun detector (9) comprises, for each control sensor (11), a convergent lens (35) disposed opposite the band-pass filter ( 17) and interposed between the light diffuser (29) and said band-pass filter (17).
    [5" id="c-fr-0005]
    5. - assembly according to claim 3, characterized in that the sunshine detector (9) comprises a single convergent lens (41) arranged vis-à-vis all bandpass filters (17) and interposed between the light diffuser (29) and said bandpass filters (17).
    [6" id="c-fr-0006]
    6. - assembly according to claim 3, characterized in that the sunshine detector (9) comprises, for each control sensor (11), a screen (47) disposed vis-à-vis the band-pass filter (17). ) associated and interposed between the light diffuser (29) and said bandpass filter (17), the screen (47) having a conical orifice (49) converging from the diffuser (29) to said bandpass filter (17) .
    [7" id="c-fr-0007]
    7. - assembly according to any one of the preceding claims, characterized in that the sunshine detector (9) comprises a plate (23) and a support (25) fixed on the plate (23) and delimiting a plurality of wells (27), the control sensors (11) being mounted on the plate (23) each at the bottom of one of the wells (27), the bandpass filters (17) being mounted in the wells (27) above the control sensors (11).
    [8" id="c-fr-0008]
    8. - System comprising a flying drone (3) and an imaging assembly (1) according to any one of the preceding claims, mounted on the drone (3).
    [9" id="c-fr-0009]
    9. - System according to claim 8, characterized in that the drone (3) comprises a body (55) having upper and lower surfaces (61, 63) intended to be turned upwards and downwards respectively when the drone (3) is hovering, the multiband sensor (5) being attached to the lower surface (63) and the sun detector (9) being attached to the upper surface (61).
    [10" id="c-fr-0010]
    10. - Method for calculating at least one characteristic quantity of the light intensity returned by a target (8) in a plurality of predetermined frequency bands, the method comprising the following steps: - flying over the target (8) to using a system comprising a flying drone (3) and an imaging assembly (1) having a sun detector (9); during the overflight, measurement by the imaging assembly (1), at a plurality of successive instants, of the light intensity returned by the target (8) in each of said predetermined frequency bands; during the overflight, measurement by the imaging assembly (1), at a plurality of successive instants, of the ambient light intensity in each of said predetermined frequency bands, and simultaneously recording of a parameter characterizing the orientation the sun detector (9) with respect to the sun (S); calculating the characteristic quantity of the light intensity reflected by the target in each predetermined frequency band by using the light intensities returned by the target in said pre-measured predetermined frequency bands and the ambient light intensities in said predetermined frequency bands previously measured; the calculation step comprising: - a substep of determining the orientation of the target (8) with respect to the sun (S); a sub-step of calculating the total light intensity received by the target (8) in one of the frequency bands, using only the ambient light intensities in said frequency band measured when a difference between the orientation of the detector of sunshine (9) relative to the sun (S) and the orientation of the target (8) relative to the sun (S) is less than a predetermined value.
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    同族专利:
    公开号 | 公开日
    US20170356799A1|2017-12-14|
    FR3052556B1|2018-07-06|
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    法律状态:
    2017-04-28| PLFP| Fee payment|Year of fee payment: 2 |
    2017-12-15| PLSC| Search report ready|Effective date: 20171215 |
    2018-05-28| PLFP| Fee payment|Year of fee payment: 3 |
    2020-03-13| ST| Notification of lapse|Effective date: 20200206 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1655459|2016-06-13|
    FR1655459A|FR3052556B1|2016-06-13|2016-06-13|IMAGING ASSEMBLY FOR DRONE AND SYSTEM COMPRISING SUCH AN ASSEMBLY MOUNTED ON A FLYING DRONE|FR1655459A| FR3052556B1|2016-06-13|2016-06-13|IMAGING ASSEMBLY FOR DRONE AND SYSTEM COMPRISING SUCH AN ASSEMBLY MOUNTED ON A FLYING DRONE|
    US15/620,323| US20170356799A1|2016-06-13|2017-06-12|Imaging assembly for a drone and system comprising such an assembly mounted on a drone|
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