Patent Publication Number: US-2020292278-A1

Title: Optronic system for a platform and associated platform

Description:
The present invention relates to an optronic system. The present invention also relates to a platform equipped with such an optronic system. 
     In the field of observation and vehicle protection, it is known to use a short-range observation device with another long-range observation device. 
     To that end, the short-range observation device includes hemispherical viewing equipment installed on a vehicle. 
     Such equipment provides an operator of the vehicle with information on the environment outside the vehicle. Among this information, in particular, 360° images are provided in real time with an elevation between 75° and −15°, each point of which is referenced precisely. 
     In some cases, the equipment is also capable of supplying moving target detection (sometimes referred to using the acronym MTD) information, laser alert detection (sometimes referred to using the acronym LAD) information and missile launch detection (sometimes referred to using the acronym MLD) information. 
     To try to best cover the entire environment of the vehicle with no hidden zone, several pieces of viewing equipment are typically arranged on the perimeter of the vehicle. This means that images coming from each piece of equipment should be merged to reproduce a single image for the operator. 
     However, such merging is delicate to perform in real time and involves, by construction, parallax problems and problems related to the presence of blind spots that are particularly bothersome when the pieces of equipment also provide moving target detection, laser alert detection and missile launch detection information. 
     Furthermore, during the movement of the vehicle, the merging is even more difficult, since there is also a need to compensate for the distortions introduced by such a movement in an image. In particular, when the vehicle is running, the movement creates blurriness in the images to be compensated. 
     There is therefore a need for an optronic system capable of supplying the aforementioned information in the surroundings of the platform and that is easy to implement. 
     To that end, the present disclosure describes an optronic system for a platform, the optronic system including a support that can be rotated about a first axis, the support defining an inner space. The optronic system includes an optronic head for observing part of the surroundings of the platform, the optronic head being mounted such that it rotates about a second axis, the second axis being perpendicular to the first axis. The optronic system includes a hemispherical viewing device comprising a sensor with an optical system having an at least hemispherical field, the sensor being able to detect images of part of the surroundings of the platform, and a calculator for processing the images that the sensor detects, the calculator being in the inner space and the sensor being secured to the support. 
     According to specific embodiments, the optronic system comprises one or more of the following features, considered alone or according to all technically possible combinations:
         the sensor is positioned on a mechanical interface, the mechanical interface being fastened on the support.   the support includes two lateral arms and a base, the mechanical interface being fastened on each lateral arm.   the calculator is capable of supplying moving target detection information, laser alert detection information and missile launch detection information.   the optronic system is provided with a protective shield independent of the support.   the optronic system is provided with a device for cleaning the hemispherical viewing device, the cleaning device including a spray nozzle, the spray nozzle being positioned on the shield.   the calculator is capable of operating at a pace greater than 1 Gigabit per second.   the sensor includes a matrix detector located in the focal plane of the optical system, means for displaying images processed by the sensor, the matrix detector being at video rate and comprising L×C pixels, with L and C&gt;2000, each pixel being double sampling correlated and suitable for ensuring a charge-voltage conversion, and 2 C parallelized analog-digital conversion (or ADC) elements, each conversion element in turn including a first ADC with an output having a low level and high gain and a second ADC with an output having a high level and low gain, the optical system having a focal distance controlled as a function of the angle of elevation, the focal distance being the longest in the equatorial plane, and has a numerical aperture of between 0.9 and 1.6, the calculator comprising means for correcting nonuniformities of the detector using correction tables adopted as a function of the temperature and the exposure time of the detector, weighted summing means, for several adjacent pixels, means for adapting the dynamics of the captured image to the dynamics of the scene, means for compressing the dynamics of the captured image as a function of the temporal noises of the detector, increasing with the illumination of the scene, means for adapting the dynamics of the captured image to the dynamics of the display and/or to those of the eye.   the calculator includes means for controlling the exposure time, the gain and the image rate of the detector as a function of the surrounding conditions, means for stabilizing the image as a function of the movements of the system or display means, means for detecting newly exposed regions of the scene, for detecting and tracking events or movements in the scene, for embedding information coming from other interfaces in the displayed image.   the optical system includes a plurality of objectives having a less extensive field than a hemispherical field.   the sensor includes a plurality of detectors each equipped with an optic, the set of optics forming the optical system.       

     The present disclosure also relates to a platform including optronic system as previously disclosed. 
     According to specific embodiments, the platform comprises one or more of the following features, considered alone or according to any technically possible combinations:
         the optronic system is unique.   the platform has a wall, the support being positioned on the wall.   the platform is a vehicle including a turret, the support being positioned on the turret.       

    
    
     
       Other features and advantages of the invention will appear upon reading the following description of embodiments of the invention, solely as an example and done in reference to the drawings, which are: 
         FIG. 1 , a schematic view of a vehicle provided with an exemplary optronic system, and 
         FIG. 2 , a schematic side view of the optronic system of  FIG. 1 . 
     
    
    
       FIG. 1  shows a vehicle  10 . 
     The vehicle  10  is a land vehicle. 
     For example, the vehicle  10  is a military-type vehicle such as a tank. 
     Such a vehicle  10  is suitable for having a plurality of weapons and protecting at least one operator installed inside the vehicle  10 . 
     According to the described example, the vehicle  10  is provided with a turret  12  on which part of an optronic system  14  is positioned. 
     For example, the turret  12  is further provided with a firing cannon  16 . 
     The vehicle  10  includes a wall  18  delimiting an inner space  20  from an outer space  22 . 
     More specifically, in the military context, the inner space  20  is the space to be secured, since it is the space in which the operator(s) will move while the outer space  22  is the operating theater in which safety is more difficult to guarantee depending on the considered surroundings. 
     The wall  18  is made from a material strong enough to form armor of the vehicle  10 , the vehicle  10  having to withstand shots. 
     The optronic system  14  is described more specifically in reference to  FIG. 2 . 
     For convenience, directions are defined. 
     A direction normal to the wall  18  is symbolized by an axis Y in  FIG. 2 . This direction corresponds to the relative bearing direction and will be called relative bearing direction Y in the remainder of the description. 
     A first transverse direction is also defined located in the plane of  FIG. 2 , the first transverse direction being perpendicular to the relative bearing direction. This direction is symbolized by an axis X in  FIG. 2 . This direction corresponds to the elevation direction and will be called elevation direction X in the remainder of the description. 
     A second transverse direction is also defined, symbolized by an axis Z in  FIG. 2 . The second transverse direction Z is perpendicular to the relative bearing direction Y and the elevation direction X. 
     The optronic system  14  includes an optronic head  24 , a support  26  and a hemispherical viewing device  28 . 
     The optronic head  24  is an optronic head  24  for observing a part of the environment of the outer space  22  of the vehicle  10 . 
     The optronic head  24  for example includes cameras able to capture the visible light, in black-and-white and/or in color, infrared cameras, telemeters, or pointers. The videos and the data collected by the optronic head  24  are sent to the interior of the vehicle  10  by means of analog and/or digital signals. 
     In this sense, the optronic head  24  is an optronic head  24  with indirect view, that is to say, an optronic head  24  providing a view via a screen that assumes the operation of all of the elements involved in the viewing of the scene on the screen. 
     The support  26  is positioned on the turret  12 . 
     The support  26  is movable about a first axis Y 1 , the first axis Y 1  being parallel to the relative bearing direction Y. 
     The support  26  is intended to keep the optronic head  24  movable relative to a second axis X 2 . The optronic head  24  is mounted rotating on the support  26  about the second axis X 2 . 
     According to the illustrated example, the second axis X 2  is parallel to the elevation direction X. 
     The support  26  includes a wall that makes it possible to delimit an inner space  30 . 
     The support  26  includes two lateral arms  32 ,  34  and a base  36 . 
     The two lateral arms  32 ,  34  and the base  36  are arranged to form a substantially U-shaped part. 
     In the specific example of  FIG. 2 , the two lateral arms  32 ,  34  are identical. 
     Each of the two lateral arms  32 ,  34  is located on either side of the optronic head  24  to provide the maintenance of the optronic head  24 . 
     Each of the lateral arms  32 ,  34  extends primarily along the relative bearing direction Y. 
     The wall of each lateral arm  32 ,  34  is made from an alloy with a base of aluminum or any other material. 
     For each of the lateral arms  32 ,  34 , an inner space  30  called lateral space  38  is defined. 
     According to the illustrated example, each lateral arm  32 ,  34  has a substantially parallelepiped shape. 
     The base  36  has two parts: a central part  40  connecting the two lateral arms  32 ,  34  and an interfacing part  42  with the wall  18 . 
     The central part  40  is hollowed out such that a central volume  44  can also be defined for the central part  40 . 
     In the case at hand, the inner space of the support  26  is therefore the sum of the lateral volumes  38  and the central space  44 . 
     The interfacing part  42  is a mechanical interface having, according to the case of  FIG. 2 , a cylinder shape with a hollowed out central part  40 , the interfacing part  42  delimiting an inner space  46 . 
     The interfacing part  42  supports an interface  48  delimiting the inner space  46 . The shape of the interface is chosen so as to adapt to the shape of the optronic head  24 . 
     The volume delimited by the sum of the inner space  46  of the interface  42  and the central space  44  of the central part  40  includes motors, resolvers intended to command the motors, as well as an electric rotary joint and/or an optical fiber that are capable of transmitting signals or data between the optronic head  24  and the inside of the vehicle  10 . 
     The motors are capable of driving a rotational movement of the support  26  relative to the wall  18  around the first axis Y 1 . 
     The interfacing part  42  is, according to the embodiments, stationary or a lift. In the case of  FIG. 2 , the interfacing part  42  is stationary. 
     The hemispherical viewing device  28  includes a mechanical interface  50 , a sensor  52 , a calculator  54 , a display unit  56  and a man-machine interface  58 . 
     The mechanical interface  50  is fastened on the rotating support  26 . 
     The mechanical interface  50  is secured to the rotating support  26 . 
     In the proposed example, the mechanical interface  50  is fastened on each lateral arm  32 ,  34 . 
     According to the example of  FIG. 2 , the mechanical interface  50  includes five parts: a first end part  60 , a first intermediate part  62 , a median part  64 , a second intermediate part  66  and a second end part  68 . 
     The first intermediate part  62  connects the first end part  60  to the median part  64  while the second intermediate part  66  connects the second end part  68  to the median part  64 . 
     Each end part is connected to a respective lateral arm  32 ,  34 . 
     The sensor  52  is able to detect images of part of the surroundings of the vehicle  10 . 
     The sensor  52  is fastened on the median part  64  of the mechanical interface  50  by holding bars. The bars are not shown in the figures for the sake of clarity of these figures. 
     For example, the sensor  52  is fastened by three holding bars. 
     In the described example, the holding bars are evenly distributed at 120°. 
     The median part  64  being secured to the support  26 , the sensor  52  is secured to the support  26 . 
     The sensor  52  corresponds to the highest point of the optronic system  14 . The distance between the sensor  52  and the wall  18  along the axis Z makes it possible to define the height of the optronic system  14 . In the described example, the height of the optronic system  14  is less than 1 meter. 
     The sensor  52  includes an optical system  72  with a hemispherical field and a detector  74 . 
     According to one variant, the sensor  52  includes a plurality of detectors  74  each equipped with an optic, the set of optics forming an optical system  72  with hemispherical field. 
     In the illustrated case, the optical system  72  has a field covering an angular range greater than or equal to a hemisphere, the axis of which is oriented toward the zenith. 
     For this reason, the optical system  72  is qualified as optical system  72  with “hemispherical field”. This expression means that the field covered by the optical system  72  is greater than or equal to a hemisphere. The term “supra-hemispherical field” is sometimes used to refer to this concept. 
     The optical system  72  has a large opening. 
     The optical system  72  has a variable resolution in the field. 
     According to one particular embodiment, the optical system  72  has major distortions in order to offer enhanced resolutions in certain angular domains, for example in the equatorial plane, to increase the range of the optic. 
     For example, the optical system  72  includes a fisheye lens, shortened to fisheye, or a hypergon lens having a focal length of 4.5 mm (millimeters) and 12 pixels per degree. The optical system  72  then includes one or two lenses as previously described to cover a field of 360°. 
     According to another example, the optical system  72  includes a plurality of objectives having a less extensive field than a hemispherical field. As an illustration, the optical system  72  is a set of three fisheye lenses, each lens having a focal length of 8 mm and 21 pixels per degree over 120°. 
     According to still another example, the optical system  72  is an optic with a very large distortion making it possible to cover a field of 360°, with a variable radial resolution along the angle of elevation that may range from 20 to 22 pixels/° or more in radial resolution. 
     The detector  74  is a matrix of photodetectors making it possible to define pixels. 
     The detector  74  is located in the focal plane of the optical system  72 . 
     For example, the detector  74  is a 4T CMOS matrix (with 4 transistors in the pixel) or more, operating at 25 Hz, with low noise (less than 2 electrons) and high dynamics (greater than 80 dB). 
     Each pixel has correlated double sampling and the charge-voltage conversion is done in each pixel, which ensures that the detector  74  has a very low noise level and high instantaneous dynamics. 
     Furthermore, the monitoring of the exposure (or integration) time, from durations shorter than 10 ps to durations of 40 ms, for example, allows the detector  74  to operate day and night. In a nighttime atmosphere, at a very low level, it is possible to increase the exposure time for example to 100 ms and to reduce the image rate for example to 10 Hz in order to improve the signal-to-noise ratio of the reproduced image. 
     The calculator  54  is suitable for processing the images that the sensor  52  can detect in order to obtain information on the surroundings of the vehicle  10 . 
     Typically, the calculator  54  is can process data having a size of several Gigabits per second. 
     Thus, the calculator  54  is capable of operating at a pace greater than or equal to 1 Gigabit per second. 
     In the described example, among the information that the calculator  54  can obtain, there is the moving target detection information, laser alert detection information and missile launch detection information. 
     The calculator  54  is in the inner space. 
     More specifically, the calculator  54  is in the inner space of the base  36 , therefore positioned before the rotary joint. 
     The display unit  56  can display images processed by the calculator  54 . 
     The display unit  56  is positioned in the inner space  20 . 
     The man-machine interface  58  allows an operator to control the hemispherical viewing device  28 . 
     The man-machine interface  58  is positioned in the inner space  20 . 
     According to the example of  FIG. 2 , the display unit  56  and the man-machine interface  58  are combined. 
     The operation of the optronic system  14  will now be described. 
     During operation, the optronic system  14  has several functions: on the one hand, owing to the optronic head  24 , the optronic system  14  makes it possible to observe part of the scene by using different cameras able to produce images in different spectral bands owing to the different cameras, for example in the visible spectrum, and in the infrared (radiation whereof the wavelength is between 800 nanometers and 14 micrometers). The cameras in particular make it possible to produce images in the following domains: NIR, SWIR, IR2 (wavelength between 3 micrometers and 5 micrometers) and IR3 (wavelength between 7.5 micrometers and 14 micrometers). 
     When the operator commands a rotation around the first axis Y 1  of the support  26  maintaining the optronic head  24 , the support  26  rotates and the observer can observe another part of the scene. 
     Furthermore, owing to the hemispherical viewing device  28 , the calculator  54  has additional information on the surroundings of the vehicle  10 . In the case at hand, the calculator  54  is able to supply real-time 360° images with an elevation of between 75° and −15° (or more in high elevation and less in low elevation), each point of which is referenced precisely. The calculator  54  is also capable of supplying moving target detection information, laser alert detection information and missile launch detection information. 
     The specific positioning of the hemispherical viewing device  28  provides the possibility for the hemispherical viewing device  28  of observing the surroundings of the vehicle  10  without concealment. In particular, the hemispherical viewing device  28  is the highest point of the vehicle  10 , which limits the concealment by other elements of the vehicle  10 . 
     Furthermore, such positioning makes it possible to better cover the off-axis illumination, which results in improved laser alert detection. 
     The positioning on the rotating support  26  also ensures rotational stabilization of the sensor  52  (mechanical slaving in relative bearing). The scrolling phenomenon of the image due to the rotational movement of the vehicle  10  or the turret  12  is thus greatly reduced. 
     The proposed optronic system  14  includes a single hemispherical viewing device  28 , which avoids positioning a plurality of hemispherical viewing devices. 
     This results in increased space on the vehicle  10  as well as a gain in terms of weight. 
     Furthermore, this avoids the difficulty of having to merge images coming from hemispherical viewing devices. 
     The optronic system  14  includes a single calculator  54 , which simplifies the information transfers. In particular, all of the information is centralized in a single place. The simplification of the information transfers implies a decrease in the connections to be made, which also results in a gain in terms of weight for the vehicle  10 . 
     The optronic system  14  is thus capable of operating with a high refresh frequency. 
     The calculator  54  further has access to additional information, namely the position of the rotating support  26 , which makes it possible to optimize the quality of the information supplied by the optronic system  14 . 
     The position of the calculator  54  also makes it possible to greatly reduce the heat signature of the optronic system  14 . 
     The position on the rotating support  26  also grants a possibility of rotating the optical system  72  to make areas of the environment visible that would be concealed by the holding bars of the sensor  52 . 
     The possibility of rotating the sensor  52  in relative bearing makes it possible to consider other embodiments using such a possibility. 
     For example, a slow rotation relative bearing of the rotating support  26  makes it possible to consider super-resolution techniques on an axis for the hemispherical viewing device  28 . 
     This makes it possible to further increase the quality of the information supplied by the calculator  54 . 
     According to another example, the optronic system  14  is provided with a protective shield independent of the rotating support  26 . 
     The shield is a protective shield protecting the optical system  72  while leaving just the optical system  72  without concealment. The protection of the shield makes it possible to protect against fragments created by an explosion or against fired bullets. It should be noted that the shield also makes it possible to reduce the heat signature of the optronic system  14 . 
     For this shield, it is also possible, according to one particular embodiment, to use the rotation of the optic. Thus, the optronic system  14  is provided with a system for cleaning the hemispherical viewing device, the cleaning device including a spray nozzle, the spray nozzle being positioned on the shield. 
     The spray nozzle is stationary and able to send a water jet, for example. 
     In a variant, the spray nozzle is able to send an air jet. 
     The cleaning of the optical system  72  is done by rotating the support. 
     Other embodiments can also be considered for the proposed optronic system  14 . 
     According to one embodiment, the optical system  72  includes a single fisheye lens. This makes it possible to simplify the connections and to use simpler image processing operations. 
     According to another embodiment, the optical system  72  includes a plurality of separate optics. 
     Furthermore, the optronic system  14  is able to operate on a plurality of spectral bands, for example in the visible spectrum, and in the infrared (radiation whose wavelength is between 800 nanometers and 14 micrometers). For example, the optronic system  14  works on the following spectral bands. NIR, SWIR, IR2 (wavelength between 3 micrometers and 5 micrometers) and IR3 (wavelength between 7.5 micrometers and 14 micrometers). To that end, the optronic system  14  for example includes a sensor  52  working on a first spectral band and an optronic head  24  working on a second spectral band, the second spectral band being separate from the first spectral band. 
     According to still another embodiment, the optronic system  14  includes both components making it possible to ensure the passive imaging and those for the active imaging. 
     In each of the described embodiments, the optronic system  14  is able to supply information on the environment of the vehicle  10 , in particular real-time 360° images with an elevation of between 75° and −15° (or more), each point of which is referenced precisely, moving target detection information, laser alert detection information and missile launch detection information. The optronic system  14  is further easy to implement. 
     The proposed optronic system  14  is usable on non-armored vehicles, ships, helicopters, airplanes or buildings. The preceding examples are jointly referred to using the generic term “platform”. 
     In general, the platform includes a wall  18  on which the support  26  is positioned. When the platform includes a part of the wall  18  corresponding to the highest location for the platform, the support  26  is advantageously positioned on said wall part  18  to benefit from the clearest possible field of view. In the described example, the wall part corresponds to the turret  12 . 
     The present invention covers all technically possible combinations of the embodiments that have been described above.