JP2017124790A - Mobile object observation system and mobile object observation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile object observation system capable of improving observation probability of a mobile object by preferentially scanning a region having high presence probability of the mobile object, and a mobile object observation method.SOLUTION: A mobile object observation system is the mobile object observation system observing a mobile object 2 moving on a locus 1. The mobile object observation system comprises: a laser device 21; an emission direction adjustment mechanism 21c adjusting an emission direction of a laser beam 11a; a laser beam light reception section 24 receiving a reflection laser beam 11b; and a control device 25. The control device 25 executes region extraction processing for extracting a first region 3 such that a total value of presence probability of the mobile object or a total value of detection probability of the mobile object is equal to a first threshold TH1 or more based on a presence probability distribution of the mobile object or a detection probability distribution of the mobile object. The first region 3 is scanned by the laser beam 11a.SELECTED DRAWING: Figure 2A

Description

  The present invention relates to a moving object observation system and a moving object observation method.

  In recent years, the need for observation of space objects (referred to as objects located in outer space) such as space debris and artificial satellites has increased. In particular, space debris around the earth has increased in recent years, and countermeasures against space debris are urgently needed in space utilization. In order to deal with space debris, it is desirable to accurately observe space debris. The need for accurate observations applies not only to space debris but also to satellite observations.

  Techniques for observing space objects using laser light have been proposed. Observation of space objects using laser light is effective in improving the accuracy of observation of space objects.

  For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2011-218834) discloses a camera mounted on an observation satellite that irradiates a measurement space of space debris with a laser beam from an artificial satellite and is in the same orbit around the earth as the artificial satellite. Discloses a technique for photographing a space to be measured and specifying space debris existing in the space to be measured from luminance information of an image obtained by photographing.

  Further, Patent Document 2 (Japanese Patent Application No. 2015-223406), which has not been disclosed at the time of patent application of the present application, discloses that the space object is irradiated with laser light from a laser device provided in the atmosphere. Techniques for observing are described.

  In order to observe a moving object by irradiating a moving object such as a space object with laser light, it is necessary to obtain reflected light with sufficient intensity. For this reason, the energy density of the laser beam irradiated to the target (area where the moving object is supposed to be present) needs to be set to a predetermined value or more by reducing the beam spot diameter (laser beam diameter) of the laser beam. There is. However, depending on the accuracy of the trajectory estimation of the moving object, an area where the moving object is assumed to exist (in other words, an assumed existence area) may be large. In such a case, when a laser beam having a beam spot diameter that covers the entire assumed existence region is irradiated, the energy density of the laser beam irradiated to the target is reduced. As a result, depending on the characteristics of the laser or the receiving performance (performance of the light receiving sensor, receiving circuit, etc.), the signal intensity required for observation (the intensity of the reflected light) may not be obtained.

JP 2011-218834 A Japanese Patent Application No. 2015-223406

  An object of the present invention is to provide a moving object observation system and a moving object observation method capable of improving the observation probability of a moving object by preferentially scanning a region having a high existence probability of the moving object. It is in.

  These objects and other objects and benefits of the present invention can be easily confirmed by the following description and the accompanying drawings.

  Hereinafter, means for solving the problem will be described using the numbers and symbols used in the embodiments for carrying out the invention. These numbers and symbols are added with parentheses for reference in order to show an example of the correspondence between the description of the claims and the mode for carrying out the invention. Accordingly, the claims should not be construed as limiting due to the bracketed description.

  The moving object observation system in some embodiments is a moving object observation system that observes the moving object (2) moving on the trajectory (1). The moving object observation system adjusts an emission direction which is a direction in which the laser beam (11a) is emitted from the laser device (21) configured to emit the laser beam (11a) and the laser device (21). An emission direction adjusting mechanism (21c), a laser beam receiving unit (24) that receives a reflected laser beam (11b) that is a reflected beam of the laser beam by the moving object (2), and a control device (25). It has. Based on the first probability distribution indicating the moving object existence probability distribution or the moving object detection probability distribution, the control device (25) calculates the total value of the moving object existence probabilities or the detection probability of the moving object. An area extraction process is performed to extract the first area (3) such that the first total value indicating the total value is equal to or greater than the first threshold (TH1). The control device (25) transmits an emission direction adjustment command to the emission direction adjustment mechanism (21c) so that the extracted first region (3) is scanned by the laser beam (21a).

  In the moving object observation system, the region extraction process may include a cell extraction process for extracting a cell from a plurality of cells (6) in which the moving object (2) is assumed to exist. The control device (25) indicates a total value of the existence probabilities of the moving object or a total value of detection probabilities of the moving object in an entire region constituted by the plurality of cells extracted by the cell extraction process. The cell extraction process may be repeatedly executed until the second total value is equal to or greater than the first threshold value. The control device (25) may end the cell extraction process when the second total value is equal to or greater than the first threshold (TH1). The said control apparatus (25) may determine the whole area | region comprised by the said some cell extracted by the said cell extraction process as said 1st area | region (3) after completion | finish of the said cell extraction process.

  In the moving object observation system, the control device (25) includes a plurality of cells (6) constituting the first region (3) in order from the cell having the high probability of existence of the moving object (2). An emission direction adjustment command may be transmitted to the emission direction adjustment mechanism (21c) so as to be scanned by the laser beam (21a).

  In the moving object observation system, the control device (25) includes a plurality of cells constituting the first region (3) in an order that makes the time required for scanning the first region (3) as short as possible. An emission direction adjustment command may be transmitted to the emission direction adjustment mechanism (21c) so that (6) is scanned.

  In the moving object observation system, a cross section perpendicular to the traveling direction of the laser light in the first region (3) may have an elongated shape corresponding to the region having the high existence probability or the detection probability.

  In the moving object observation system, the first region (3) may be a region whose position is fixed.

  In the moving object observation system, as an example in which it is appropriate that the first region is a region whose position is fixed, a case where the first region can be scanned in a sufficiently short time can be considered. For example, the size of the cross section is such that the area of the beam spot (4) of the laser beam (11a) when the laser beam (11a) reaches the estimated trajectory of the moving object (2), and the laser beam ( 11a), the first area can be scanned in a sufficiently short time when it is smaller than the product of the emission frequency indicating the number of times of emission per unit time. In such a case, the position of the first region may be fixed.

  In the moving object observation system, the first area (3) may be an area that moves with time.

  In the moving object observation system, as an example in which it is appropriate that the first region is a region that moves with time, a case where the first region cannot be scanned in a sufficiently short time can be considered. For example, the size of the cross section is such that the area of the beam spot (4) of the laser beam (11a) when the laser beam (11a) reaches the estimated trajectory of the moving object (2), and the laser beam ( If it is larger than the product of the emission frequency indicating the number of times of emission per unit time of 11a), the first region cannot be scanned in a sufficiently short time. In such a case, the position of the first region may be moved with time.

  In the moving object observation system, the first area (3) may be an area that moves with time. The shape of the first region (3) may be a thin plate shape or a linear shape extending in a direction perpendicular to the estimated trajectory of the moving object (2).

  In the moving object observation system, when one axis along a direction perpendicular to the estimated trajectory of the moving object (3) is defined as an X axis, the cell extraction process includes the step of: It may be executed under the constraint that cells having the same position along the X axis are excluded from extraction target candidates.

  In the moving object observation system, the control device (25) may transmit the emission direction adjustment command to the emission direction adjustment mechanism so that the first region is repeatedly scanned with the laser light.

  In the moving object observation system, the control device (25) includes the existence probability distribution of the moving object (2) in a second observation period different from the first observation period in which the first region (3) is scanned, or Based on the second probability distribution indicating the detection probability distribution of the moving object (2), the integrated value of the existence probability of the moving object (2) or the integrated value of the detection probability of the moving object (2) is a second threshold (TH2). ) The second area extraction process for extracting the second area (103) may be executed so as to achieve the above. The control device (25) may transmit the emission direction adjustment command to the emission direction adjustment mechanism (21c) so that the second region (103) is scanned by the laser beam (11a). Good.

  In the moving object observation system, the second probability distribution may be a probability distribution calculated by reflecting an observation result of the moving object in the first observation period.

  The moving object observation method in some embodiments is a method of observing the moving object (2) moving on the trajectory (1). The moving object observation method includes a step of obtaining a first probability distribution indicating an existence probability distribution of the moving object (2) or a detection probability distribution of the moving object (2) in a first observation period; A step of extracting the first region (3) based on the total value of the existence probability of the moving object or the total value of the detection probability of the moving object based on a first threshold (TH1); The step of emitting the laser beam (11a) so that (3) is scanned by the laser beam (11a), and the reflected laser beam (11b) that is the reflected light of the laser beam by the moving object (2) is received. And a step of detecting the moving object (2).

  According to the present invention, it is possible to provide a moving object observation system and a moving object observation method capable of improving the observation probability of a moving object by preferentially scanning a region having a high existence probability of the moving object.

FIG. 1 is a conceptual diagram schematically showing a positional relationship between a moving object observation system of the first embodiment and a moving object. FIG. 2A is a functional block diagram illustrating an example of the configuration of the moving object observation system. FIG. 2B is a functional block diagram illustrating another example of the configuration of the moving object observation system. FIG. 3 is a graph schematically showing the existence probability distribution of a moving object. FIG. 4 is a diagram schematically illustrating an example of the first region. FIG. 5 is a diagram schematically illustrating a state in which laser light travels through the region A along the Y-axis direction. FIG. 6 is a diagram for explaining a method for calculating the existence probability of a moving object in each cell. FIG. 7 is a diagram schematically illustrating the existence probability distribution of a moving object. FIG. 8 is a diagram schematically illustrating an example of the first region. FIG. 9 is a diagram schematically illustrating an example of the first region. FIG. 10A is a diagram schematically illustrating an example of the first region in the fixed coordinate system. FIG. 10B is a diagram schematically illustrating the emission timing of the laser light applied to the cell. FIG. 11 is a diagram schematically illustrating an example of the first area in the coordinate system that moves together with the first area. FIG. 12 is a diagram schematically illustrating how the moving first region is scanned a plurality of times. FIG. 13 is a graph showing an expected value of the number of times that the moving object is irradiated with the laser light when the first region is repeatedly irradiated. FIG. 14 is a diagram schematically illustrating an example of the first region. FIG. 15 is a diagram schematically illustrating the existence probability distribution of a moving object. FIG. 16 is a diagram schematically showing that the existence probability distribution is a function of time. FIG. 17 is a diagram schematically illustrating an example of the first region. FIG. 18A is a diagram schematically illustrating an example of the first region in the fixed coordinate system. FIG. 18B is a diagram schematically illustrating the emission timing of the laser light applied to the cell. FIG. 19 is a diagram schematically illustrating an example of the first area in the coordinate system that moves together with the first area. FIG. 20 is a diagram schematically illustrating a state in which the moving first region is scanned a plurality of times. FIG. 21 is a graph showing an expected value of the number of times the moving object is irradiated with the laser light when the first region is repeatedly irradiated. FIG. 22 is a graph showing an expected value of the number of times that the moving object is irradiated with the laser light when the first region is repeatedly irradiated. FIG. 23 is a flowchart schematically showing the moving object observation method. FIG. 24 is a diagram schematically showing the state of observation by the moving object observation system of the second embodiment. FIG. 25 is a conceptual diagram illustrating an example of calculating the existence probability distribution of a moving object reflecting the first observation result. FIG. 26 is a conceptual diagram illustrating an example in which the size of the second region is made larger than the size of the first region, reflecting the first observation result. FIG. 27 is a diagram schematically showing the state of observation by the moving object observation system of the third embodiment.

Hereinafter, a moving object observation system and a moving object observation method according to embodiments will be described with reference to the accompanying drawings. In the accompanying drawings, the same or similar components may be referred to by the same or corresponding reference numerals.

(Coordinate system)
In this specification, the following three-dimensional orthogonal coordinate system is used for explanation. The Z axis is an axis along the estimated trajectory of the moving object. The + Z direction is a direction along the estimated trajectory of the moving object and means the traveling direction of the moving object. The X axis and the Y axis are each perpendicular to the Z axis. The X axis is perpendicular to the Y axis. Note that the X axis may be oriented in any direction within a plane perpendicular to the Z axis.

(First embodiment)
FIG. 1 is a conceptual diagram schematically showing an arrangement relationship between the moving object observation system 10 of the first embodiment and the moving object 2. The moving object observation system 10 is configured to observe (detect) the moving object 2. The moving object 2 is a moving object that moves on the orbit 1 such as the Earth orbit. The moving object 2 is a space object, for example. The space object may be defined as an object located in outer space or may be defined as an object existing outside the atmosphere. The space object may be an artificial satellite or space debris.

As can be seen from FIG. 1, the moving object observation system 10 emits a laser beam 11a. More specifically, the laser device in the main body 10a of the moving object observation system 10 emits laser light 11a. The moving object observation system 10 emits the laser beam 11a toward the portion in the first region 3 so that the first region 3 is scanned by the laser beam 11a. Some embodiments and modifications are characterized by the extraction of the first region 3. Details of the extraction of the first region 3 will be described later. In the example illustrated in FIG. 1, the moving object 2 exists within the irradiation range of the laser light 11 a, more specifically, within the beam spot 4. The diameter of the beam spot 4 may mean the diameter of the laser beam in a cross section perpendicular to the traveling direction of the laser beam 11a. The diameter of the beam spot 4 may be, for example, the diameter of a portion where the intensity of the laser beam in the cross section becomes 1 / e ² (e is a natural logarithm base) of the maximum intensity of the laser light in the cross section.

  The moving object observation system 10 (more specifically, a laser light receiving unit 24 described later) receives the reflected laser light 11 b that is the reflected light of the laser light from the moving object 2. By analyzing the reflected laser beam 11b, the position of the moving object is specified. For example, based on the reception of the reflected laser beam 11b, it may be determined that the moving object 2 exists in the irradiation direction of the laser beam 11a. Additionally, the distance between the moving object 2 and the moving object observation system 10 (more specifically, the laser device 21) based on the difference between the emission time of the laser beam 11a and the reception time of the reflected laser beam 11b. May be calculated. Furthermore, the velocity of the object in the laser emission direction may be calculated based on the Doppler shift of the reflected light.

  In the example shown in FIG. 1, the moving object observation system 10 is installed on the ground. Alternatively, part or all of the moving object observation system 10 may be installed at a place other than the ground. For example, a part or all of the moving object observation system 10 may be installed on the sea, may be installed on a moving body such as a vehicle, an aircraft, or a ship, or may be installed in outer space (artificial satellite or space). Station).

  FIG. 2A is a functional block diagram illustrating an example of the configuration of the moving object observation system 10. In the example illustrated in FIG. 2A, the moving object observation system 10 includes a laser oscillator 21a, an irradiation optical system 21b, a separation mirror 23, a laser light receiving unit 24, and a control device 25.

  The laser oscillator 21a and the irradiation optical system 21b constitute a laser device 21 for emitting laser light 11a. Specifically, the laser oscillator 21a generates a laser beam 11a to be irradiated onto the moving object 2. The laser beam 11a generated by the laser oscillator 21a passes through the separation mirror 23 and enters the irradiation optical system 21b. In the example shown in FIG. 2A, a pulse laser that generates pulsed laser light and can adjust pulse energy and pulse repetition frequency is used as the laser oscillator 21a. The pulse repetition frequency is equivalent to the emission frequency indicating the number of times the laser beam 11a is emitted per unit time.

  On the other hand, the irradiation optical system 21b emits the laser beam 11a received from the laser oscillator 21a toward the first region 3, and receives the reflected laser beam 11b generated by the reflection of the laser beam 11a by the moving object 2. Then, the received reflected laser beam 11 b is emitted toward the separation mirror 23. The irradiation optical system 21b may include a lens barrel and a drive unit that drives the lens barrel. The driving unit is controlled by the control device 25, and thereby the direction of the lens barrel, that is, the emission direction of the laser beam 11a (the direction of the optical axis of the laser beam 11a emitted from the laser device 21) is controlled. In the example shown in FIG. 2A, the drive unit that drives the lens barrel constitutes an emission direction adjusting mechanism 21c that adjusts the emission direction of the laser beam 11a. In other words, the emission direction of the laser beam 11a can be changed by the drive unit (the emission direction adjusting mechanism 21c) that drives the lens barrel. Alternatively or additionally, a drive unit that changes the angle of the mirror that reflects the laser beam 11a may constitute the emission direction adjusting mechanism 21c. Alternatively or additionally, the drive unit that rotates the main body 10a itself of the moving object observation system 10 is the emission direction adjusting mechanism 21c. By rotating the main body 10a itself, the emission direction of the laser light 11a May be changed. Alternatively or additionally, the emission direction of the laser light 11a may be changed by an optical phased array.

  In the first embodiment, the irradiation optical system 21b has a spread angle of the laser light 11a emitted from the irradiation optical system 21b, for example, by adjusting the position of the lens in the irradiation optical system 21b using a drive unit. It may be configured to be adjustable. That is, the irradiation optical system 21b may include a divergence angle adjustment mechanism (beam spot diameter adjustment mechanism 21d). The spread angle of the laser beam may be defined as an angle formed by the center of the optical axis of the laser beam and a light component (half width) having an intensity half that of the output peak value of the laser beam.

  The separation mirror 23 is used for separating the laser beam 11a and the reflected laser beam 11b. The separation mirror 23 transmits the laser beam 11a and reflects the reflected laser beam 11b. Alternatively, the separation mirror 23 may reflect the laser beam 11a and pass the reflected laser beam 11b. The reflected laser light 11 b from the separation mirror 23 enters the laser light receiving unit 24.

  The laser beam receiving unit 24 receives the reflected laser beam 11b and images it. In this embodiment, by analyzing the difference between the emission time of the laser beam 11a and the reception time of the reflected laser beam 11b, the moving object 2 and the moving object observation system 10 (more specifically, the laser device 21) are analyzed. The distance between them can be calculated. Depending on the relationship between the distance from the moving object observation system 10 to the moving object and the pulse repetition frequency, a plurality of laser beams 11a are emitted from the time when the reflected laser beam 11b is received after the emission of the laser beam 11a. Thus, it may not be possible to specify which laser beam 11a the received reflected laser beam 11b corresponds to. In this case, the difference between the emission time of the laser beam 11a and the reception time of the reflected laser beam 11b is estimated and estimated based on the approximate distance from the moving object observation system 10 to the moving object calculated from the prior information. The laser beam 11a having the closest difference between the time difference and the actually measured time may be specified as the laser beam 11a corresponding to the received reflected laser beam 11b. The prior information may be data acquired by the moving object observation system 10 in the past (moving object existence probability distribution data itself, moving object position data, orbit data, velocity data, etc. Or data acquired in advance using other observation devices (position data of moving objects, orbit data, velocity data, etc.), or other observations. It may be data provided from a station (may be moving object existence probability distribution data itself, moving object position data, orbit data, velocity data, etc.).

  The control device 25 controls at least the laser oscillator 21a and the emission direction adjusting mechanism 21c. The control device 25 may control the entire moving object observation system 10. In addition, the control device 25 functions as a calculation unit that performs various calculations necessary for observation by the moving object observation system 10. For example, the control device 25 is configured to execute a region extraction process to be described later for extracting the first region 3. Further, the control device 25 processes imaging data obtained by converting the reflected laser light 11b imaged by the laser light receiving unit 24, and derives the position of the moving object 2, the image of the moving object 2, and the like. Also good. The control device 25 may be composed of one computer or a plurality of computers. The control device 25 (computer) may include a CPU and a storage device. The storage device temporarily stores data necessary for calculation, and stores a calculation program for executing calculation such as area extraction processing described later.

  The control device 25 extracts the first region 3 by executing a region extraction process described later. Then, the control device 25 transmits an emission direction adjustment command to the emission direction adjustment mechanism 21c so that the first region 3 is scanned by the laser light 11a. In addition, the control device 25 may adjust (change) the spread angle of the laser light 11a emitted from the irradiation optical system 21b by controlling the beam spot diameter adjusting mechanism 21d. In addition, the control device 25 may control the operation of the laser oscillator 21a so that the first region 3 is scanned by the laser light 11a. For example, the pulse energy and the pulse repetition frequency may be adjusted by controlling the operation of the laser oscillator 21a. In addition, the control device 25 controls the operation timing of the laser oscillator 21a, and the laser light receiving unit 24 receives the reflected laser light 11b in active range gating so that data corresponding to the first region 3 is acquired. The timing to perform may be determined.

  In the moving object observation system 10 having such a configuration, it is possible to perform laser ranging that specifies the distance to the moving object 2. In addition, in the moving object observation system 10, the direction of the moving object 2 (for example, the direction indicating the angle in the horizontal plane) is based on the emission direction of the laser light 11a (in one example, the direction of the lens barrel) and the captured image. It is possible to specify the angle and the elevation angle indicating the angle in the vertical plane. In the moving object observation system 10, the three-dimensional position of the moving object 2 can be specified based on the distance to the moving object 2 and the direction of the moving object 2.

  Note that the optical system for emitting the laser beam 11a toward the first region 3 and the optical system for receiving the reflected laser beam 11b may be separated. FIG. 2B is a functional block diagram illustrating the moving object observation system 10 having such a configuration. The moving object observation system 10 in FIG. 2B is configured in the same manner as the moving object observation system 10 in FIG. 2A, but includes a light receiving optical system 26 instead of the separation mirror 23.

In the moving object observation system 10 in FIG. 2B, the irradiation optical system 21 b emits the laser light 11 a received from the laser oscillator 21 a toward the first region 3. Further, the light receiving optical system 26 receives the reflected laser light 11 b generated by the reflection of the laser light 11 a by the moving object 2, and makes the received reflected laser light 11 b enter the laser light receiving unit 24. Each of the irradiation optical system 21b and the light receiving optical system 26 may include a lens barrel and a drive unit that drives the lens barrel. The driving units of the irradiation optical system 21b and the light receiving optical system 26 are controlled by the control device 25, and thereby the directions of the respective barrels of the irradiation optical system 21b and the light receiving optical system 26 may be controlled. In the example shown in FIG. 2B, the drive unit that drives the lens barrel constitutes an emission direction adjusting mechanism 21c that adjusts the emission direction of the laser beam 11a. In other words, the emission direction of the laser beam 11a can be changed by the drive unit (the emission direction adjusting mechanism 21c) that drives the lens barrel. Alternatively or additionally, a drive unit that changes the angle of the mirror that reflects the laser beam 11a may constitute the emission direction adjusting mechanism 21c. Alternatively or additionally, the emission direction of the laser light 11a may be changed by an optical phased array.
Other configurations and operations of the moving object observation system 10 in FIG. 2B are the same as the configurations and operations of the moving object observation system 10 in FIG. 2A.

(Outline of the first area)
The outline of the first region will be described with reference to FIGS. 3 and 4. FIG. 3 is a graph schematically showing the existence probability distribution of a moving object. FIG. 4 is a diagram schematically illustrating an example of the first region.

  The existence probability distribution of the moving object 2 may be calculated on the basis of data (moving object position data, trajectory data, velocity data, etc.) acquired in advance using another observation device, or other observation stations. May be calculated on the basis of data provided from (which may be the existence probability distribution data of the moving object itself, or may be position data, trajectory data, velocity data, etc. of the moving object). 3 that the existence probability distribution with respect to the direction along the Z axis (the direction of the estimated trajectory of the moving object) is more dispersed than the existence probability distribution with respect to the direction along the X axis or the Y axis. The inventor of the present application recognizes that the existence probability distribution with respect to the direction along the Z axis is likely to diffuse due to an error in the estimation of the speed of the moving object. In FIG. 3, a region A identified by oblique lines is a region having an elliptical sphere shape as shown in FIG. 4. The probability that the moving object 2 exists in the region A at a certain observation time is an integral value (total value) of the probability that the moving object 2 exists in an arbitrary minute region in the region A. In the first embodiment, the first region 3 (for example, the region A) is extracted such that the integral value (total value) of the existence probability of the moving object 2 is equal to or greater than the first threshold value. In the example described in FIG. 4, the first region 3 is a region having an elliptic sphere shape.

(Beam spot diameter)
FIG. 4 shows four beam spots 4. In the example illustrated in FIG. 4, the entire first region 3 is scanned by four times of laser light irradiation corresponding to the four beam spots 4. The size of the beam spot 4 in the first region 3 (in other words, the beam spot diameter) may be adjusted by the beam spot diameter adjusting mechanism 21d described above. The control device 25 has a beam spot diameter when the laser light 11a reaches the first region 3 under the constraint that the intensity of the reflected laser light 11b received by the laser light receiving unit 24 is not less than a detectable intensity. (In other words, the beam spot diameter calculation process for calculating the beam spot diameter when the laser beam 11a reaches the estimated trajectory of the moving object 2) may be executed. From the standpoint of quickly scanning the first region 3, the beam spot diameter is preferably larger. The control device 25 transmits an adjustment command to the beam spot diameter adjusting mechanism 21d so that the beam spot diameter calculated by the beam spot diameter calculating process is realized.

(First example of the first region)
A first example of the first region 3 will be described with reference to FIGS. In order not to complicate the description, it is assumed that the traveling direction of the laser light 11a coincides with the Y axis. In this case, as shown in FIG. 5, the laser beam 11a passes through the region A and travels along the Y-axis direction, so that the existence probability distribution of the moving object in the Y-axis direction can be ignored. . In other words, the Y-axis direction can be observed with substantially no leakage by laser light irradiation.

  On the other hand, in the XZ plane, it is necessary to consider the existence probability distribution of the moving object. With reference to FIG. 6, a method of calculating the existence probability of the moving object 2 in the cell 6 that divides the XZ plane will be described. The length of the cell 6 in the Y-axis direction is a length that sufficiently covers an area where the moving object 2 is assumed to exist. Further, the size of the cell 6 (for example, the cross-sectional area of the cell 6 in the XZ plane) corresponds to the size of the beam spot 4. For example, the size of the cross-sectional area of the cell 6 may be the largest of the sizes contained in the beam spot 4 or may divide the beam spot 4 into several.

  For example, as shown in FIG. 6A, the existence probability of the moving object 2 in each small region 5 is given to each of the plurality of small regions 5 finely divided on the XZ plane ( In other words, when the existence probability distribution of the moving object 2 is given corresponding to each small region 5), the existence probability of the moving object 2 in each cell 6 is a plurality of included in the corresponding cell 6. It is an integral value (total value) of the existence probability of the moving object 2 in the small region 5. On the other hand, as shown in FIG. 6B, when the existence probability distribution of the moving object 2 in the direction along the X axis and the existence probability distribution of the moving object 2 in the direction along the Z axis are given, For example, the existence probability of the moving object 2 in the cell 6 indicated by hatching in FIG. 6D is equal to the existence probability (the area of the portion indicated by hatching) of the moving object 2 in the section E in FIG. 6) and the existence probability of the moving object 2 in the section F in FIG. 6C (corresponding to the area of the portion indicated by the oblique lines) can be approximately calculated. The section E is a section divided along the X-axis direction and is a section corresponding to the existence probability calculation target cell 6, and the section F is a section divided along the Z-axis direction. Thus, it is a classification corresponding to the existence probability calculation target cell 6.

  As described above, the existence probability of the moving object 2 in each cell 6 is calculated. As an example, the calculation result of the existence probability of the moving object 2 in each cell 6 is shown in FIG. FIG. 7 is a diagram schematically illustrating the existence probability distribution of the moving object 2. In FIG. 7, cell IDs (for example, “6-1” and “6-2”) are described in the lower part of each cell 6, and the moving object 2 in the cell 6 is displayed in the upper part of each cell 6. The existence probability is described (for example, the existence probability of the moving object 2 in the cell whose ID is “6-13” is “0.11 (11%)”). The order of the existence probability is listed. For example, the existence probability of the moving object 2 in the cell whose ID is “6-13” is the “1” th highest among all the cells, and the moving object 2 in the cell whose ID is “6-12”. Is the second highest probability among all cells.

  In the present embodiment, based on the existence probability distribution of the moving object 2, the control device 25 has an integrated value (total value) of the existence probability of the moving object equal to or higher than the first threshold TH1 (or the first threshold TH1 or higher and the second threshold). The region extraction process for extracting the first region 3 is executed so that the value is equal to or less than TH2. The control device 25 is based on the first association data shown in FIG. 7, that is, the first association data that associates the cell ID, the existence probability of the moving object, and data indicating the order of the existence probability of the moving object. Then, the region extraction process for extracting the first region 3 is performed so that the integral value (total value) of the existence probability of the moving object is equal to or higher than the first threshold value TH1 (or higher than the first threshold value TH1 and lower than the second threshold value TH2). May be.

  For example, it is assumed that the first threshold TH1 is “0.66” and the second threshold TH2 is an arbitrary value greater than the first threshold and smaller than “1.00”. The second threshold may be “0.67”, “0.70”, or “0.95”, but is not “1.00”. . If the control device 25 is programmed to end the integration when the integral value of the moving object existence probability becomes equal to or higher than the first threshold value, the second threshold value TH2 need not be set.

  In the example illustrated in FIG. 7, the total value (integrated value) of the existence probabilities of the moving object 2 in a plurality of cells marked with a circle is “0.66”. For this reason, the control apparatus 25 may extract the area | region corresponding to the several cell by which the circle was attached | subjected as a 1st area | region. More specifically, the control device 25 may repeat the process of adding the existence probability of the moving object 2 in the cell in order from the cell having the highest existence probability of the moving object 2. The addition is continued until the total value (integrated value) resulting from the addition becomes equal to or greater than the first threshold value TH1. And the control apparatus 25 extracts the area | region corresponding to the some cell used for addition of presence probability as the 1st area | region 3. FIG. For example, in the example shown in FIG. 7, the existence probability “0.11” in the cell 6-13, the existence probability “0.10” in the cell 6-12,..., The existence probability “0. 02 ”and the existence probability“ 0.01 ”in the cell 6-11 are added in this order. As a result of adding the existence probabilities from the cell 6-1 having the highest existence probability to the cell 6-11 having the highest existence probability, the total value (integration value) of the existence probabilities becomes equal to or greater than the first threshold value. . For this reason, the control device 25 extracts, as the first region 3, an area configured from the cell having the highest existence probability to the Nth (herein, eleventh) cell having the highest existence probability.

  In other words, the area extraction process executed by the control device 25 includes a cell extraction process. In the cell extraction process, a cell is selected from a plurality of cells 6 (for example, 25 cells including cells 6-1 to 6-25 in the example shown in FIG. 7) in which the moving object 2 is assumed to exist. Is a process of sequentially extracting. The control device 25 repeatedly executes the cell extraction process until the total value of the existence probabilities of the moving object 2 in the entire region constituted by all the extracted cells is equal to or greater than the first threshold value TH1. The control device 25 ends the cell extraction process when the total value of the existence probabilities of the moving object 2 in the entire region configured by all the extracted cells is equal to or greater than the first threshold value TH1. And a control apparatus determines the whole area | region comprised by all the cells extracted by the cell extraction process as the 1st area | region 3 after completion | finish of a cell extraction process.

  In the cell extraction process, it is assumed that the size of the cross-sectional area of the cell 6 is the largest of the sizes included in the beam spot 4. If the size of the cross-sectional area of the cell 6 is a size that divides the beam spot 4, all the cells 6 included in the beam spot are extracted by one cell extraction process and correspond to the extracted cell 6. Then, the existence probability is added. When adding the existence probability, the value obtained by multiplying the existence probability by a coefficient in consideration of the intensity of the beam passing through each cell (value obtained by adding weight to the existence probability) You may add. Note that setting the cross-sectional area of the cell 6 to be the maximum of the size included in the beam spot 4 reduces the load on the computer and executes the region extraction processing at a higher speed. This is desirable. On the other hand, setting the cross-sectional area of the cell 6 so as to divide the beam spot 4 is desirable for more accurately calculating the total value of existence probabilities.

  6 and 7, the shape of the cell 6 is a square (or a rectangular parallelepiped having a square cross section and extending in the Y-axis direction), but the shape of the cell 6 is limited to a square or a rectangular parallelepiped. Not. In the examples shown in FIGS. 5 to 7, it is assumed that the traveling direction of the laser light 11a coincides with the Y axis. However, the traveling direction of the laser light 11a may not coincide with the Y axis. When the traveling direction of the laser beam 11a does not coincide with the Y axis, it is necessary to consider the existence probability distribution of the moving object 2 with respect to the direction along the Y axis. In this case, for example, the space is divided by cells 6 (cells having a rectangular parallelepiped shape) having a plane parallel to the XY plane, a plane parallel to the YZ plane, and a plane parallel to the ZX plane. The existence probability of the moving object 2 is acquired. That is, the existence probability distribution of the moving object 2 is acquired. And the control apparatus 25 extracts the area | region comprised from the cell with the highest existence probability to the cell with the Nth highest existence probability as the 1st area | region 3. FIG. “N” is selected such that the existence probability of the moving object 2 in the first region is equal to or higher than the first threshold value TH1.

  In the examples described in FIGS. 6 and 7, the existence probability distribution of the moving object 2 is the existence probability distribution of the moving object 2 at a certain observation time. Alternatively, the existence probability distribution of the moving object 2 may be the existence probability distribution of the moving object in a certain observation period. For example, the existence probability distribution of the moving object 2 may be the existence probability distribution of the moving object in the first observation period (for example, 1 second). The observation time is a concept included in the observation period. That is, if the observation period is ultimately shortened, the observation period becomes equivalent to the observation time.

  FIG. 8 shows an example of the first region 3 obtained by region extraction processing by the control device 25. In FIG. 8, the shaded area corresponds to the first area 3. In addition, the number attached | subjected in the cell 6 is a number which shows the order of the height of existence probability. As shown in FIG. 8, the cross-sectional shape of the cross section perpendicular to the traveling direction of the laser light in the first region 3 (for example, the cross section perpendicular to the Y axis) is an elongated shape corresponding to the region having a high existence probability. In the example illustrated in FIG. 8, the first region 3 has a shape in which the length in the Z-axis direction is longer than the length in the X-axis direction.

  The control device 25 transmits an emission direction adjustment command to the emission direction adjustment mechanism 21c described above so that the first region 3 is scanned with the laser light. For example, the control device 25 emits light to the emission direction adjustment mechanism 21c so that the plurality of cells 6 constituting the first region 3 are scanned with the laser light 11a in order from the cell with the high probability of existence of the moving object 2. Send direction adjustment command. As a result, in the example illustrated in FIG. 8, the plurality of cells 6 are scanned by the laser light 11 a in the order indicated by the numbers given in the cells 6. More specifically, the control device 25 first transmits an emission direction adjustment command to the emission direction adjustment mechanism 21c so that the laser beam 11a is irradiated to the cell 6 to which the numeral “1” is attached. As a result, the irradiation optical system 21b is adjusted so that the optical axis of the laser beam 11a is directed to the cell 6 to which the numeral “1” is attached. Then, the laser beam 11a generated by the laser oscillator 21a is irradiated to the cell 6 to which the numeral “1” is attached. Next, the control device 25 transmits an emission direction adjustment command to the emission direction adjustment mechanism 21c so that the laser beam 11a is irradiated to the cell 6 to which the number “2” is attached. As a result, the irradiation optical system 21b is adjusted so that the optical axis of the laser beam 11a is directed to the cell 6 to which the numeral “2” is attached. Then, the laser beam 11a generated by the laser oscillator 21a is irradiated to the cell 6 to which the numeral “2” is attached. Similarly, when “K” is a natural number greater than or equal to “3” and less than or equal to “N”, the control device 25 emits the laser beam 11a so that the cell 6 with the number “K” is irradiated. An emission direction adjustment command is transmitted to the direction adjustment mechanism 21c. As a result, the irradiation optical system 21b is adjusted so that the optical axis of the laser beam 11a is directed to the cell 6 to which the numeral “K” is attached. Then, the laser beam 11a generated by the laser oscillator 21a is irradiated to the cell 6 to which the numeral “K” is attached.

  In many cases, the existence probability distribution of the moving object 2 changes with the passage of time. Therefore, scanning with the laser light 11a in order from the cell having the higher existence probability of the moving object 2 It can be said that it is preferable from the viewpoint of improving the observation probability (detection probability) of 2. In addition, when the result obtained by scanning can be analyzed immediately, it is preferable to scan in order from a cell having a high existence probability of the moving object 2. In such a case, when the reflected laser beam 11b is obtained, it is possible to stop the current scan and start the next scan. Alternatively or additionally, it is possible to reflect observation results such as the obtained reflected laser beam 11b in determining the next scanning region or the next scanning timing.

  Note that the order in which the cells are scanned is not necessarily limited to the above order. For example, the control device 25 outputs the emission direction so that the plurality of cells 6 constituting the first region 3 are scanned in such an order that the time required for scanning the first region 3 with the laser light 11a is as short as possible. An emission direction adjustment command may be transmitted to the adjustment mechanism 21c. When the result obtained by scanning cannot be analyzed immediately, it is preferable to scan the plurality of cells 6 in an order that makes the time required for scanning the first region 3 as short as possible. By shortening the time required for scanning the first region 3 as much as possible, the number of scans within the observation time can be increased. As a result, the observation probability (detection probability) of the moving object 2 is improved.

  In the example illustrated in FIG. 8, it is assumed that the first region 3 does not move during the first observation period (for example, 1 second). In other words, the first region 3 is a region whose position is fixed in the first observation period. When the time required for scanning the first region 3 with the laser light is relatively short, it is effective to make the first region 3 a region whose position is fixed in the first observation period. For example, the size of the cross section of the first region 3 shown in FIG. 8 (the cross section perpendicular to the traveling direction of the laser light 11a) is the emission frequency of the laser light 11a and the beam spot of the laser light 11a in the first region 3. 4 is smaller than the product of the area of 4 (in other words, the area of the beam spot of the laser beam when the laser beam reaches the estimated trajectory of the moving object), the first region 3 is positioned in the first observation period. It is effective to use a region where is fixed.

  In the above example, the first region 3 is scanned only once by the laser beam 11a. Alternatively, the first region 3 may be repeatedly scanned with the laser light 11a. In other words, the control device 25 may transmit an emission direction adjustment command to the emission direction adjustment mechanism 21c so that the first region 3 is repeatedly scanned by the laser light 11a. For example, the control device 25 emits light to the emission direction adjustment mechanism 21c so that the plurality of cells 6 constituting the first region 3 are scanned with the laser light 11a in order from the cell with the high probability of existence of the moving object 2. Send direction adjustment command. As a result, in the example shown in FIG. 8, a plurality of cells 6 are scanned with the laser light 11a in accordance with the order indicated by the numbers given in the cells 6 (first scan). Next, the control device 25 again causes the emission direction adjustment mechanism so that the plurality of cells 6 constituting the first region 3 are scanned with the laser light 11a in order from the cell with the high probability of existence of the moving object 2. An emission direction adjustment command is transmitted to 21c. As a result, in the example shown in FIG. 8, the plurality of cells 6 are scanned again by the laser light 11a in accordance with the order indicated by the numbers given in the cells 6 (second scanning).

  In the above example, the target area for the first scan and the target area for the second scan are the same area. Alternatively, the target area for the first scan and the target area for the second scan may be different areas. FIG. 9 shows an example in which the first area 3a corresponding to the second scan is different from the first area 3 corresponding to the first scan. In the example shown in FIG. 9, in the first scan, the first region 3 is scanned with the laser beam 11a, and in the second scan, the first region 3a is scanned with the laser beam 11a. In the example shown in FIG. 9, the first area 3 corresponding to the first scan and the first area 3a corresponding to the second scan have the same shape and size. The first region 3a is located at a position moved from the first region 3 by a distance L in the + Z direction. The distance L is obtained by, for example, multiplying the time between the start time of the first scan and the start time of the second scan by the estimated speed of the moving object 2. In other words, the control device 25 may pour the first region 3a based on the first region 3 and the distance L calculated based on the estimated speed of the moving object. The order in which the plurality of cells in the first area 3a are scanned may be the same as the order in which the plurality of cells in the first area 3 are scanned. That is, the control device 25 may determine the order in which the plurality of cells in the first area 3a are scanned based on the order in which the plurality of cells in the first area 3 are scanned.

  In this specification, the interval between scans indicates the time between the end time of the first scan and the start time of the second scan. For example, in the example illustrated in FIG. 9, the time when the laser beam is emitted toward the cell 6 with the number “11” in the first scan and the number “1” in the second scan. The time between the time when the laser beam is emitted toward the cell marked with is the inter-scan interval. The interval between the scans is typically shorter than the observation interval described later. The interval between scans may be, for example, a period selected from 0.1 seconds to 10 seconds. The interval between scans may be “zero” (that is, the second scan may be started immediately after the first scan).

(When considering temporal variation of existence probability distribution)
When the time required for scanning the first region 3 with the laser light 11a is relatively long, it is effective to extract the first region 3 in consideration of temporal variation of the existence probability distribution of the moving object 2. It is. For example, the size of the cross section of the first region 3 shown in FIG. 8 (the cross section perpendicular to the traveling direction of the laser beam 11a) is determined by the emission frequency of the laser beam 11a, the emission frequency of the laser beam 11a, and the first region 3. The presence of the moving object 2 is larger than the product of the area of the beam spot 4 of the laser beam 11a (in other words, the area of the beam spot of the laser beam when the laser beam reaches the estimated trajectory of the moving object) It is effective to extract the first region 3 in consideration of the temporal variation of the probability distribution.

  In order not to complicate the description, the first region 3 shown in FIG. 8 is + Z direction by a length corresponding to the length (Z direction length) of the two cells 6 during the irradiation interval of the laser beam 11a. Assume that you move to In other words, it is assumed that the first region 3 moves with time (with the passage of time). In this case, as shown in FIG. 10A, the center cell of the first region 3 (cell numbered with “1”) is the length of the two cells 6 during the irradiation interval of the laser light 11a. Move in the + Z direction by the length corresponding to. In the first irradiation with the laser beam 11a, the laser beam 11a passes through the first cell with the number “1” and a hatched line. In the second irradiation with the laser beam 11a, the laser beam passes through the second cell with the numeral “2”. Similarly, in the “K” -th irradiation of the laser beam 11a, the laser beam passes through the K-th cell marked with the number “K”. “K” is an arbitrary natural number of 3 or more and N or less.

  The emission timing of the laser beam 11a irradiated to each cell is as shown in FIG. 10B. As can be understood from FIG. 10B, the laser light is irradiated to the cell according to the order indicated by the numbers at every laser light irradiation interval (every T seconds). That is, in the XYZ coordinate system, which is a fixed coordinate system, the first region 3 scanned by the laser beam 11a is the entire region indicated by hatching in FIG. 10A. On the other hand, in the X′Y′Z ′ coordinate system that moves together with the first region (where the Z ′ axis is an axis along the estimated trajectory of the moving object), the first region 3 scanned by the laser light 11a is: In FIG. 11, the entire area indicated by hatching. In FIG. 10A or FIG. 11, the number and arrangement of the cells constituting the first region 3 are the total probability (integral of the probability that the moving object 2 exists in the cell at the time when each cell is irradiated with laser light. Value) is set to be equal to or greater than the first threshold value TH1. In other words, the number and arrangement of the cells constituting the first region 3 are set such that the probability that the laser beam hits the moving object 2 is equal to or higher than the first threshold TH1 by N times of irradiation with the laser beam 11a. ing. The specific setting method will be described with reference to FIGS. 6 and 7 except that the calculation of the probability that the moving object 2 exists in each cell is performed based on the existence probability distribution that varies with time. This is the same as the above example.

  10A and 11, it is assumed that the traveling direction of the laser light 11a coincides with the Y axis (or Y ′ axis), but the traveling direction of the laser light 11a is the Y axis (or Y ′). Does not have to coincide with the axis). When the traveling direction of the laser beam 11a does not coincide with the Y axis (or Y ′ axis), it is necessary to consider the existence probability distribution of the moving object 2 with respect to the direction along the Y axis (or Y ′ axis). In this case, for example, the cell is a cell 6 having a plane parallel to the X′Y ′ plane, a plane parallel to the Y′Z ′ plane, and a plane parallel to the Z′X ′ plane (cell having a rectangular parallelepiped shape). And the existence probability of the moving object 2 in each cell 6 is acquired. That is, the existence probability distribution of the moving object 2 is acquired. Note that the existence probability and the existence probability distribution are functions of time. And the control apparatus 25 extracts the area | region comprised from the cell with the highest existence probability to the cell with the Nth highest existence probability as the 1st area | region 3. FIG. “N” is selected such that the existence probability of the moving object 2 in the first region is equal to or higher than the first threshold value TH1.

  In addition to the first scan corresponding to FIG. 10A, the first region 3 that moves with time may be scanned again with laser light. FIG. 12 is a diagram schematically illustrating how the first region 3 that moves with time is scanned a plurality of times (for example, twice). In FIG. 12, the distance L is a distance corresponding to the time between the start time of the first scan and the start time of the second scan. The distance L is obtained, for example, by multiplying the time between the start time of the first scan and the start time of the second scan by the estimated speed of the moving object 2.

With respect to the examples shown in FIGS. 9 and 12, when the first region 3 is repeatedly irradiated, an expected value of the number of times the moving object 2 is irradiated with the laser light 11a is obtained by numerical calculation. FIG. 13 is a graph showing the results obtained by numerical calculation. The preconditions for numerical calculation are as follows.
Prerequisite:
(1) Expansion of trajectory in the X-axis direction: First parameter (2) Expansion of trajectory in the Z-axis direction: It is assumed that the trajectory is twice as large as the trajectory in the X-direction.
(3) It is assumed that the expansion of the trajectory in the X-axis direction and the expansion of the trajectory in the Z direction do not change within the observable time range.
(4) Presence probability distribution of moving object: Gaussian distribution is assumed.
(5) Observable time: 100 seconds (assuming an altitude of 700 km)
(6) Moving object speed: 7.5 km / s (assuming an altitude of 700 km)
(7) Laser light pulse repetition frequency (emission frequency): 1 kHz
(8) Beam spot diameter: second parameter (9) Interscan interval: 1 second (10) Moving object existence probability threshold (first threshold): Third parameter

  Referring to (a) of FIG. 13, when the beam spot diameter is 10 m, the moving object 2 emits laser light when the existence probability threshold is “1” (in other words, when the first region is not set). The expected value of the number of times of irradiation is “1”. On the other hand, when the existence probability threshold is “0.6” (in other words, when the first region where the total value of the existence probability of moving objects is 60% is scanned with laser light), the moving object 2 is The expected value of the number of times of irradiation with laser light is about “22” at the maximum. Therefore, in the moving object observation system in the embodiment, it is understood that the probability that a moving object is observed is greatly improved.

  Referring to FIG. 13B, when the beam spot diameter is 20 m, the moving object 2 is irradiated with laser light when the existence probability threshold is “1” (in other words, when the first region is not set). The expected value of the number of times of irradiation is “1”. On the other hand, when the existence probability threshold is “0.8” (in other words, when the first region where the total value of the existence probability of moving objects is 80% is scanned with laser light), the moving object 2 is The expected value of the number of times of irradiation with laser light is about “42” at the maximum. Therefore, in the moving object observation system in the embodiment, it is understood that the probability that a moving object is observed is greatly improved.

  Referring to FIG. 13C, when the beam spot diameter is 80 m, when the existence probability threshold is “1” (in other words, when the first region is not set), the moving object 2 is irradiated with the laser beam. The expected value of the number of times of irradiation is “1”. On the other hand, when the existence probability threshold is “0.9” (in other words, when the first area where the total value of the existence probability of moving objects is 90% is scanned with laser light), the moving object 2 is The expected value of the number of times of irradiation with the laser light is about “60” at the maximum. Therefore, in the moving object observation system in the embodiment, it is understood that the probability that a moving object is observed is greatly improved.

  Referring to the graphs shown in FIGS. 13A to 13C, the integral value (total value) of the existence probability of the moving object 2 is not less than “0.1 (first threshold value)” and “0.98 (first value). When the first region 3 is extracted so as to be a value belonging to the range of “2 threshold)” or less, it is expected that a suitable observation result is obtained.

(Second example of the first region)
A second example of the first region 3 will be described with reference to FIGS. 14 to 22.

  In the second example, the shape of the first region 3 is a thin plate shape (for example, a flat plate shape or a curved plate shape) or a line extending in a direction perpendicular to the estimated trajectory (the estimated trajectory substantially coincides with the actual trajectory 1). This is a region having a shape (for example, a linear shape or a curved shape). In the example shown in FIG. 14, when the time t = t2, the thin plate-shaped first region 3 is scanned with the laser light 11a. In the example illustrated in FIG. 14, the shape of the first region 3 is a cross-sectional shape of a columnar region that is long in the Z-axis direction, that is, a disc shape.

  In order not to complicate the description, it is assumed that the traveling direction of the laser light 11a coincides with the Y axis. In this case, since the laser beam 11a passes through the first region 3 and travels along the Y-axis direction, the existence probability distribution of the moving object with respect to the Y-axis direction can be ignored. In other words, the Y-axis direction can be observed with substantially no leakage by laser light irradiation.

  On the other hand, in the XZ plane, it is necessary to consider the existence probability distribution of the moving object. The existence probability of the moving object 2 in the cell 6 that divides the XZ plane is calculated by a method as shown in FIG. 6, for example. The length of the cell 6 in the Y-axis direction is a length that sufficiently covers an area where the moving object 2 is assumed to exist. Further, the size of the cell 6 (for example, the cross-sectional area of the cell 6 in the XZ plane) corresponds to the size of the beam spot 4. For example, the size of the cross-sectional area of the cell 6 may be the largest of the sizes included in the beam spot 4.

  The method for calculating the existence probability of the moving object 2 in each cell 6 is the same as the method described above with reference to FIG. FIG. 15 shows an example of the calculation result of the existence probability of the moving object 2 in each cell 6. FIG. 15 shows the existence probability distribution of the moving object 2. For example, the existence probability distribution is a function of time (see FIG. 16 if necessary). In FIG. 15, cell IDs (for example, “6-1” and “6-2”) are described in the lower part of each cell 6, and the moving object 2 in the cell 6 is displayed in the upper part of each cell 6. The existence probability is described (for example, the existence probability of the moving object 2 in the cell whose ID is “6-7” is “0.12 (12%)”). The order of the existence probability is listed. For example, the existence probability of the moving object 2 in the cell whose ID is “6-7” is the “1” th highest among all the cells, and the moving object 2 in the cell whose ID is “6-11”. Is the second highest probability among all cells.

  In the present embodiment, based on the existence probability distribution of the moving object 2, the control device 25 determines that the integral value of the existence probability of the moving object is greater than or equal to the first threshold TH1 (or greater than or equal to the first threshold TH1 and less than or equal to the second threshold TH2). A region extraction process for extracting the first region 3 is executed as described above. The control device 25 is based on the first association data shown in FIG. 15, that is, the first association data that associates the cell ID, the existence probability of the moving object, and the data indicating the order of the existence probability of the moving object. Thus, the region extraction processing for extracting the first region 3 may be executed so that the integral value of the existence probability of the moving object is equal to or higher than the first threshold value TH1 (or higher than the first threshold value TH1 and lower than the second threshold value TH2). .

  For example, it is assumed that the first threshold is “0.27” and the second threshold is an arbitrary value greater than the first threshold and smaller than “1.00”. The second threshold may be “0.28” or “0.30”, but is not “1.00”. If the control device 25 is programmed to end the integration when the integral value of the moving object existence probability becomes equal to or greater than the first threshold value, the second threshold value need not be set.

  In the example illustrated in FIG. 15, the total value (integrated value) of the existence probabilities of the moving object 2 in a plurality of cells marked with a circle is “0.27”. For this reason, the control device 25 may extract a region corresponding to a plurality of cells with circles as the first region 3. More specifically, the control device 25 may repeat the process of adding the existence probability of the moving object 2 in the cell in order from the cell having the highest existence probability of the moving object 2. At this time, the control device 25 extracts only one cell having the highest existence probability of the moving object 2 from a plurality of cells having the same position along the X-axis direction (direction perpendicular to the Z-axis). To do. For example, in the example illustrated in FIG. 15, the control device 25 first extracts the cell 6-7 having the highest existence probability of the moving object 2. Further, the total value (integrated value) of the existence probabilities is set to “0.12”. And the control apparatus 25 determines not to extract the cell 6-5, the cell 6-6, and the cell 6-8 whose positions along the X-axis direction are the same as the cell 6-7. In order not to extract cell 6-5, cell 6-6, and cell 6-8, whether or not a flag indicating that extraction is not possible is given to each of cell 6-5, cell 6-6, and cell 6-8 Alternatively, the existence probability of the moving object in each of the cells 6-5, 6-6, and 6-8 may be rewritten to zero. Next, the control device 25 extracts the cell 6-11 having the highest existence probability of the moving object 2 from the cells that can be extracted. In addition, the control device 25 adds “0.11” to the total value (integrated value) of the existence probabilities. As a result, the total value (integrated value) of the existence probabilities becomes “0.23”. And the control apparatus 25 determines not to extract the cell 6-9, the cell 6-10, and the cell 6-12 whose position along the X-axis direction is the same as the cell 6-11. Next, the control device 25 extracts the cell 6-3 having the highest existence probability of the moving object 2 from the cells that can be extracted. Further, the control device 25 adds “0.04” to the total value (integrated value) of the existence probabilities. As a result, the total value (integrated value) of the existence probabilities becomes “0.27”. When the total value (integrated value) of the existence probabilities becomes equal to or higher than the first threshold value, the control device 25 ends the cell extraction. In this manner, in the example illustrated in FIG. 15, the control device 25 extracts the area including the cell 6-7, the cell 6-11, and the cell 6-3 as the first area 3.

  In the example illustrated in FIG. 15, the control device 25 is configured to extract only one cell from a plurality of cells having the same position along the X-axis direction (direction perpendicular to the Z-axis). Under the condition, the existence probabilities of the moving object 2 in the cell are repeatedly added in order from the cell having the highest existence probability of the moving object 2. The addition is continued until the total value (integrated value) resulting from the addition becomes equal to or greater than the first threshold value. And the control apparatus 25 extracts the area | region corresponding to the some cell used for addition of presence probability as the 1st area | region 3. FIG.

  In the example illustrated in FIG. 15, the existence probability distribution of the moving object 2 is the existence probability distribution of the moving object 2 at a certain observation time. Alternatively, the existence probability distribution of the moving object 2 may be the existence probability distribution of the moving object in a certain observation period. For example, the existence probability distribution of the moving object 2 may be the existence probability distribution of the moving object in the first observation period (for example, 1 second). The observation time is a concept included in the observation period. That is, if the observation period is ultimately shortened, the observation period is equivalent to the observation time.

  Alternatively, when the cell to be irradiated Kth (“K” is a natural number equal to or greater than 1) is defined as the “Kth cell”, the control device 25 applies the laser beam irradiation time to the first cell. Based on the existence probability distribution of the moving object 2 at, the existence probability of the moving object in the first cell is calculated, and the calculated existence probability is added to the total value (integration value) of the existence probabilities, Based on the existence probability distribution of the moving object 2 at the irradiation time of the laser beam, the existence probability of the moving object in the Kth cell is calculated, and the calculated existence probability is added to the total value (integration value) of the existence probabilities, Next, based on the existence probability distribution of the moving object 2 at the irradiation time of the laser light to the (K + 1) th cell, the existence probability of the moving object in the (K + 1) th cell is calculated, and the calculated existence probability is calculated as the total value of the existence probabilities. To add to (integral value) The management, the total value of the existence probability (integral value) may be repeatedly performed until more than a first threshold value. And the control apparatus 25 extracts the area | region corresponding to the some cell used for addition of presence probability as the 1st area | region 3. FIG. In addition, when the irradiation time of the laser beam to the first cell is T1, the irradiation time of the laser beam to the Kth cell is “K−1” at the irradiation interval (reciprocal of the emission frequency) at T1. You may acquire by adding the value obtained by multiplying. At this time, in the process of extracting the (K + 1) th cell, the control device 25, under the constraint that any one of the first cell to the Kth cell and the cell having the same position in the direction along the X axis are excluded. The cell with the highest probability of moving object may be extracted as the (K + 1) th cell. Alternatively, in the process of extracting the (K + 1) th cell, the control device 25 has the same constraint condition that the first cell to the Kth cell are excluded, and the position in the direction along the Z axis is the same as that of the first cell. Under the constraint that only the cell is an extraction candidate, the cell with the highest moving object existence probability may be extracted as the (K + 1) th cell. In this case, the first area 3 is a flat area perpendicular to the Z axis or a linear area perpendicular to the Z axis through the first cell.

  FIG. 17 shows an example of the first region 3 obtained by region extraction processing by the control device 25. In the example shown in FIG. 17, the irradiation time of the laser beam to the first cell and the irradiation time of the laser beam to the Nth cell (the third cell in the example shown in FIG. 17) to which the laser beam is irradiated last. In this example, the moving object hardly moves, in other words, the laser light irradiation interval is ultimately short. In FIG. 17, the shaded area corresponds to the first area 3. In addition, the number attached | subjected in the cell 6 is a number corresponding to the order of a cell with high existence probability. As shown in FIG. 17, the shape of the first region 3 is a thin plate shape (more specifically, a flat plate shape) extending in a direction perpendicular to the Z axis.

  FIG. 18A shows an example of the first region 3 obtained by region extraction processing by the control device 25. In the example shown in FIG. 18A, the irradiation time of the laser light to the first cell and the irradiation time of the laser light to the Nth cell (the third cell in the example shown in FIG. 18A) that is finally irradiated with the laser light. In this case, it is assumed that the moving object moves a relatively large distance. In FIG. 18A, in order not to complicate the description, the first region 3 shown in FIG. 17 corresponds to the length (Z direction length) of the two cells 6 for each irradiation interval of the laser light 11a. It is assumed that only the length moves in the + Z direction. In this case, as shown in FIG. 18A, the first cell in the first region 3 moves in the + Z direction by a length corresponding to the length of the two cells 6 at each irradiation interval of the laser light 11a. In the first irradiation with the laser beam 11a, the laser beam 11a passes through the first cell with the number “1” and a hatched line. In the second irradiation with the laser beam 11a, the laser beam passes through the second cell with the numeral “2”. Similarly, in the “K” -th irradiation of the laser beam 11a, the laser beam passes through the K-th cell marked with the number “K”. “K” is an arbitrary natural number of 3 or more and N or less.

  The emission timing of the laser beam 11a applied to each cell is as shown in FIG. 18B. As can be understood from FIG. 18B, the laser light is irradiated to the cell in accordance with the order indicated by the numbers at every laser light irradiation interval (every T seconds). That is, in the XYZ coordinate system, which is a fixed coordinate system, the first region 3 scanned by the laser light 11a is the entire region indicated by hatching in FIG. 18A. On the other hand, in the X′Y′Z ′ coordinate system that moves together with the first region (where the Z ′ axis is an axis along the estimated trajectory of the moving object), the first region 3 scanned by the laser light 11a is: In FIG. 19, the entire region indicated by the oblique lines is formed. In the coordinate system that moves together with the first region, the shape of the first region 3 is a thin plate shape (more specifically, a flat plate shape) that extends in a direction perpendicular to the Z ′ axis.

  In FIG. 18A or FIG. 19, the number and arrangement of the cells constituting the first region 3 are the total value (integrated value) of the probability that the moving object 2 exists in the cell at the time when the laser beam 11a is irradiated to each cell. ) Is set to be equal to or greater than the first threshold value TH1. In other words, the number and arrangement of the cells constituting the first region 3 are set so that the probability that the moving object 2 will be irradiated with the laser light N times or more is equal to or higher than the first threshold value TH1. Yes. The specific setting method is the same as in the above example.

  In the examples described in FIGS. 18A and 19, it is assumed that the traveling direction of the laser beam 11 a coincides with the Y axis (or Y ′ axis). However, the traveling direction of the laser beam 11 a is the Y axis (or Y ′). Does not have to coincide with the axis). When the traveling direction of the laser beam 11a does not coincide with the Y axis (or Y ′ axis), it is necessary to consider the existence probability distribution of the moving object 2 with respect to the direction along the Y axis. In this case, for example, the cell is a cell 6 having a plane parallel to the X′Y ′ plane, a plane parallel to the Y′Z ′ plane, and a plane parallel to the Z′X ′ plane (cell having a rectangular parallelepiped shape). And the existence probability of the moving object 2 in each cell 6 is acquired. That is, the existence probability distribution of the moving object 2 is acquired. Note that the existence probability and the existence probability distribution are functions of time. And the control apparatus 25 extracts the area | region comprised from the cell with the highest existence probability to the cell with the Nth highest existence probability as the 1st area | region 3. “N” is selected such that the existence probability of the moving object 2 in the first region is equal to or higher than the first threshold value TH1.

  In addition to the first scan corresponding to FIG. 18A, the first region 3 that moves with time may be scanned again with laser light. FIG. 20 is a diagram schematically illustrating how the first region 3 that moves with time is scanned a plurality of times (for example, twice). In FIG. 20, the distance L is a distance corresponding to the time between the start time of the first scan and the start time of the second scan. The distance L is obtained, for example, by multiplying the time between the start time of the first scan and the start time of the second scan by the estimated speed of the moving object 2.

In the example shown in FIG. 20, when the first region 3 is repeatedly irradiated, the expected value of the number of times the moving object 2 is irradiated with the laser light 11a is obtained by numerical calculation. FIG. 21 is a graph showing the results obtained by numerical calculation. The preconditions for numerical calculation are as follows.
Prerequisite:
(1) Expansion of trajectory in the X-axis direction: First parameter (2) Expansion of trajectory in the Z-axis direction: It is assumed that the trajectory is twice as large as the trajectory in the X-direction.
(3) It is assumed that the expansion of the trajectory in the X-axis direction and the expansion of the trajectory in the Z direction do not change within the observable time range.
(4) Presence probability distribution of moving object: Gaussian distribution is assumed.
(5) Observable time: 100 seconds (assuming an altitude of 700 km)
(6) Moving object speed: 7.5 km / s (assuming an altitude of 700 km)
(7) Laser light pulse repetition frequency (emission frequency): 1 kHz
(8) Beam spot diameter: second parameter (9) Interscan interval: 1 second (10) Moving object existence probability threshold: Third parameter

  In order to facilitate comparison, in FIG. 21, the existence probability threshold is a threshold obtained by normalizing the first threshold. That is, the existence probability threshold value in FIG. 21 is a normalized threshold value obtained by dividing the first threshold value by the probability that a moving object exists in an area composed of all cells having the same Z-direction position as the first cell. is there.

  Referring to (a) of FIG. 21, when the beam spot diameter is 10 m, the expected value of the number of times the moving object 2 is irradiated with the laser beam when the normalized existence probability threshold is “0.99”. Is a maximum of about “1.5”. Therefore, in the moving object observation system in the embodiment, it is understood that the probability that the moving object is observed is improved.

  Referring to (b) of FIG. 21, when the beam spot diameter is 20 m, the expected value of the number of times the moving object 2 is irradiated with the laser beam when the normalized existence probability threshold is “0.99”. Is a maximum of about “3.0”. Therefore, in the moving object observation system in the embodiment, it is understood that the probability that the moving object is observed is improved.

  Referring to (c) of FIG. 21, when the beam spot diameter is 30 m and the normalized existence probability threshold is “0.99”, the expected value of the number of times the moving object 2 is irradiated with the laser light Is a maximum of about “4.5”. Therefore, in the moving object observation system in the embodiment, it is understood that the probability that the moving object is observed is improved.

(Comparative example)
As a comparative example for FIG. 21, when the first region 3 that does not move with time is repeatedly irradiated, the number of times the moving object 2 is irradiated with the laser light 11a is obtained by numerical calculation. The result of the numerical calculation is shown in FIG. The preconditions for the numerical calculation are the same as the preconditions for the numerical calculation corresponding to FIG. Referring to FIG. 21, in any case where the beam spot diameter is 10 m, 20 m, or 30 m, the expected value of the number of times the moving object 2 is irradiated with the laser beam is about “ 1.1 ". Therefore, in the comparative example, it can be said that the improvement of the probability that a moving object is observed cannot be expected so much. However, when the improvement in the observation probability of the moving object may be small, or when the scanning of the first region 3 by the laser beam 11a is executed at an extremely high speed, this comparative example is also an implementation of the present invention. Can be in form.

(Method for observing moving objects)
Next, a moving object observation method using the above-described moving object observation system will be described. FIG. 23 is a flowchart schematically showing a moving object observation method in the embodiment.

  In the first step S1, the existence probability distribution of the moving object in the first observation period is acquired. The existence probability distribution may be a function of time. Alternatively, if the first observation period is a short period, the existence probability distribution may be approximated to be constant during the first observation period (in other words, it may not be a function of time). ). The existence probability distribution may be calculated by the control device 25 based on data acquired in advance using another observation device, or may be calculated by the control device 25 based on data provided from another observation station. It may be calculated. Alternatively, the existence probability distribution that has already been calculated by another apparatus may be transmitted to the control apparatus 25 so that the control apparatus 25 may acquire the existence probability distribution.

  In the second step S2, the first region 3 is extracted based on the acquired existence probability distribution so that the total value of the existence probabilities of the moving objects is equal to or greater than the first threshold value TH1. The extraction of the first area is performed by the control device 25. As the first region extraction method, any one of the above-described methods described with reference to FIGS. 6 to 8, 10A to 11, 6 and 15 to 17, or FIGS. 18A to 19 is used. May be adopted.

  In the third step S3, the laser beam 11a is emitted so that the first region 3 is scanned by the laser beam 11a. The laser beam 11a is emitted using the laser device 21 described above. In addition, the control apparatus 25 transmits the emission direction adjustment command to the above-described emission direction adjustment mechanism 21c so that each cell 6 in the first region is scanned in order. Upon receiving the emission direction adjustment command, the emission direction adjustment mechanism 21c drives the drive unit of the irradiation optical system 21b so that the optical axis of the laser light 11a is directed to the cell to be irradiated. When the moving object 2 is irradiated with the laser beam 11a, the reflected laser beam 11b is generated by the moving object 2.

  In the fourth step S4, the laser light receiving unit 24 receives the reflected laser light 11b. The moving object 2 is detected by receiving the reflected laser beam 11b. More specifically, data corresponding to the reflected laser light 11b received by the laser light receiving unit 24 is transmitted to an analysis device such as the control device 25, and the moving object 2 is detected by analyzing the data by the analysis device. It is confirmed. The reflected laser beam 11b may be received during the execution of the third step S3 or may be performed after the execution of the third step S3.

  In the moving object observation method in the embodiment, a region (first region) with a high existence probability of a moving object is preferentially searched. For this reason, it is possible to improve the observation probability of the moving object.

  In the moving object observation method described above, the first region 3 described above may be a fixed region during the scanning period by the laser beam 11a, or may be a region that moves with the movement of the moving object 2. Good. In the moving object observation method described above, the first region 3 may be scanned a plurality of times by the laser beam 11a. The shape of the first region 3a scanned in the second scan may be the same as or slightly different from the shape of the first region 3 scanned in the first scan. If the shape of the existence probability distribution of the moving object in the second scanning period is relatively different from the shape of the existence probability distribution of the moving object in the first scanning period, the second scanning is performed. The shape of the first region 3a is preferably different from the shape of the first region 3 scanned in the first scan.

  When the first region 3 is scanned a plurality of times, as shown in FIGS. 13 and 21, by changing the beam spot diameter or the first threshold value TH1, the expected number of irradiation times (the moving object is a laser beam). (Expected value of the number of times of irradiation) changes. For this reason, the control device 25 may execute a beam spot diameter and / or first threshold value determination process prior to the extraction of the first region 3. That is, the control device 25 determines the beam spot diameter and / or the first threshold value TH1 based on the existence probability distribution of the moving object 2 so that the expected number of times of irradiation is optimum (for example, maximum). For example, the control device 25 acquires in advance second association data indicating the relationship between the first threshold value TH1, the expected number of irradiation times, the beam spot diameter, and the spread of the trajectory. The first threshold value TH1 and / or the beam spot diameter is determined based on the spread of the trajectory matching the existence probability distribution of the object 2 and the second association data so that the expected number of times of irradiation is optimized. It may be. The determined first threshold value TH1 is used for calculating the first region 3. Further, the control device 25 transmits an adjustment command to the beam spot diameter adjusting mechanism 21d so that the determined beam spot diameter is realized. When receiving the adjustment command, the beam spot diameter adjusting mechanism 21d drives the drive unit of the irradiation optical system 21b so that the beam spot diameter of the laser light reaching the first region 3 becomes the determined beam spot diameter.

  For example, when the spread of the existence probability distribution of the moving object is large (when the estimation accuracy of the existence position of the moving object is low), when the spread of the existence probability distribution of the moving object is small (the estimation accuracy of the existence position of the moving object is In some cases, the observation probability (detection probability) of the moving object may be improved when the first threshold value is set to be small compared to the high case. Therefore, the control device 25 is configured to execute a first threshold value changing process for changing the first threshold value so that the first threshold value becomes smaller as the spread of the existence distribution probability of the moving object becomes larger. May be.

(Second Embodiment)
FIG. 24 is a diagram schematically showing the state of observation by the moving object observation system 10 of the second embodiment. The moving object observation system 10 of the second embodiment includes the same components as the moving object observation system of the first embodiment. A repeated description of each component of the moving object observation system 10 will be omitted. In the second embodiment, a plurality of observation periods are set. The first observation is an observation performed between time OT1 and time OT2. The second observation is an observation performed between time OT3 and time OT4.

  The first observation is performed using the moving object observation method described with reference to FIG. Briefly, based on the existence probability distribution of the moving object 2 in the first observation period, the control device 25 sets the first value so that the integral value (total value) of the existence probability of the moving object is equal to or greater than the first threshold value TH1. A first area extraction process for extracting the area 3 is executed. Then, the control device 25 transmits an emission direction adjustment command to the emission direction adjustment mechanism 21c so that the first region 3 is scanned with the laser light.

  The second observation is performed using the moving object observation method described with reference to FIG. Briefly described, the control device 25 is based on the existence probability distribution of the moving object 2 in the second observation period different from the first observation period in which the first observation is performed. A second area extraction process is performed to extract the second area 103 so that the total value) is equal to or greater than the second threshold value TH2. The setting of the second threshold TH2 is performed in the same manner as the setting of the first threshold TH1 described above. Then, the control device 25 transmits an emission direction adjustment command to the emission direction adjustment mechanism 21c so that the second region 103 is scanned with the laser light.

  An observation interval may be set between the first observation and the second observation. The observation interval is typically longer than the inter-scan interval described above. For example, the observation interval may be a period selected from 3 seconds to 200 seconds. The observation interval is between the first observation end time OT2 (for example, the time when the emission of the laser beam 11a is ended) and the second observation start time OT3 (for example, the time when the emission of the laser beam 11a is restarted). It is a period between. In the second embodiment, the observation probability (detection probability) of the moving object is improved by setting a plurality of observation periods. It should be noted that the first observation period and the second observation period may be determined by the control device 25 so as to be in a time region where the observation probability is high. For example, the control device 25 determines a first observation period, a second observation period, and an observation interval between the first observation and the second observation according to the environment around the moving object observation system 10. May be. The surrounding environment is, for example, the state of cloud dispersion in the sky, the direction of the sun, the flight status of the aircraft, the distribution of other obstacles, and the like. For example, when a cloud exists between the laser device 21 of the moving object observation system 10 and an area where the existence probability of the moving object is high at a certain first time, the control device 25 performs the first observation period or the second observation time. A first observation period and a second observation period (a plurality of observation periods) are set so that the first time is not included in the observation period (a plurality of observation periods). In other words, the control device 25 allows the first observation period and the first observation period so that the first time is before the first observation period, after the second observation period, or during the observation interval. Two observation periods (multiple observation periods) are set. In this case, the control device 25 only needs to be configured to acquire meteorological data (temporal change in cloud dispersion state) from another system in addition to the temporal change in the existence probability distribution of the moving object 2.

  Alternatively, or in addition, when the sun is present on or near the straight line from the laser device 21 of the moving object observation system 10 to a region where the existence probability of the moving object is high at a certain first time, The control device 25 sets the first observation period and the second observation period (a plurality of observation periods) so that the first time is not included in the first observation period or the second observation period (a plurality of observation periods). It may be set. In this case, the control device 25 only needs to be configured to acquire data on temporal changes in the direction of the sun in addition to temporal changes in the existence probability distribution of the moving object 2.

  When the control device 25 determines the first observation period and the second observation period according to the environment around the moving object observation system 10, the observation probability (detection probability) of the moving object is further improved.

  Note that the existence probability distribution (second probability distribution) of the moving object in the second observation period is a probability distribution calculated by reflecting the result of the first observation (observation result of the moving object in the first observation period). May be. For example, when the moving object 2 is not observed in the first observation, the control device 25 may determine that the probability that the moving object 2 does not exist in the first region 3 is high. For example, when calculating the existence probability distribution (second probability distribution), the control device 25 selects the first region 3 between the region corresponding to the first region 3 in the first observation period (for example, between the time OT1 and the time OT3). May be executed by reducing the existence probability of the moving object in the first region after the movement obtained by assuming that the moving object 2 moves at the estimated speed of the moving object 2. FIG. 25 is a conceptual diagram showing the above-described example in which the existence probability distribution is calculated by reflecting the first observation result. In the example shown in FIG. 25, the second region 103 (region shown by oblique lines) scanned by the laser light 11a in the second observation period is the first region after moving (region corresponding to the first region 3). Excluded area.

  Alternatively or additionally, if the moving object 2 is not observed in the first observation, the control device 25 indicates that the second region 103 scanned by the laser light 11a in the second observation period is the first region 103. You may set the 2nd area | region 103 so that it may become an area | region wider than the 1st area | region 3 scanned with the laser beam 11a in the observation period. For example, the control device 25 sets the second threshold value TH2 such that the second threshold value TH2 is smaller than the first threshold value TH1. As a result, the second region 103 is wider than the first region 3. FIG. 26 is a conceptual diagram showing the above example in which the size of the second region is enlarged to reflect the first observation result. In the example shown in FIG. 26, the second area 103 (area shown by oblique lines) scanned by the laser beam 11a in the second observation period is the first area after movement (area corresponding to the first area 3). And a wider area than the first area after movement.

  When the moving object 2 is observed in the first observation, the control device 25 scans the second region 103 scanned by the laser beam 11a in the second observation period with the laser beam 11a in the first observation period. The second area 103 may be set so as to be smaller than the first area 3 that has been set. That is, when the presence position data of the moving object 2 is newly calculated based on the observation result in the first observation period, smaller areas are concentrated in the second observation period based on the existence position data. Observed.

  In addition, when it takes time to analyze whether or not the moving object 2 is observed in the first observation, in other words, whether or not the moving object 2 is observed in the first observation is determined in the second observation period. When it is unknown until just before, the second area 103 (area shown by oblique lines) scanned by the laser beam 11a in the second observation period is the first area after movement (area corresponding to the first area 3) itself. There may be.

  In addition, when the moving object 2 is observed in both the first observation period and the second observation period, the control device 25 includes the moving object existence position data in the first observation period and the moving object in the second observation period. It is possible to calculate the speed of the moving object 2 based on the existence position data. Further, when the moving object 2 is observed in both the first observation period and the second observation period, the moving object existence position data in the first observation period and the moving object existence position data in the second observation period are Based on this, the control device 25 can calculate whether the altitude of the moving object 2 is increasing, the altitude of the moving object 2 is decreasing, or whether the altitude of the moving object 2 is maintained. It is.

  In the embodiment, in addition to the first observation period and the second observation period, another observation period (for example, a third observation period) may be set. In addition, a second observation interval is provided between the second observation period and the third observation period, in other words, between the second observation end time OT4 and the third observation start time. Also good. The second observation interval may be a longer interval than the above-described inter-scan interval. Further, the second observation interval may be a period having the same length as the observation interval between the first observation period and the second observation period, or may be a period having a different length.

(Third embodiment)
A third embodiment will be described with reference to FIG. The moving object observation system 10 in the third embodiment includes all the components of the moving object observation system in the first embodiment. In addition, the moving object observation system 10 in the third embodiment includes a radio wave observation device 60 and / or an optical observation device 70. The radio wave observation device 60 and / or the optical observation device 70 are used to acquire the existence probability distribution of the moving object 2.

  The radio wave observation device 60 radiates radio waves (typically microwaves) toward outer space, and observes the reflected waves generated by the reflection of the radio waves by the moving object 2. On the other hand, the optical observation device 70 observes reflected sunlight from the moving object 2. For example, the optical observation device 70 includes an astronomical telescope and an imaging device installed on the ground, and the moving object 2 can be observed by acquiring an image of the moving object 2 with the imaging device.

  The radio observation device 60 and / or the optical observation device 70 transmits the preliminary observation information 90 a and 90 b to the control device 25 of the moving object observation system 10. The prior observation information is information obtained by observation by the radio wave observation apparatus 60 and / or the optical observation apparatus 70 (both of which function as a prior observation station). The prior observation information may be information including the time when the moving object 2 is observed and the position of the moving object 2 at the time. Alternatively, the prior observation information may be information including the time when the moving object 2 is observed and the position and speed of the moving object 2 at the time. Note that the position information of the moving object may include azimuth angle information and angle-of-attack information in a direction from the radio wave observation device 60 or the optical observation device 70 toward the moving object 2. Further, the position information of the moving object may include distance information from the radio wave observation device 60 or the optical observation device 70 to the moving object 2.

  The observation area in the observation by each of the radio wave observation device 60 and / or the optical observation device 70 may be determined by, for example, external prior observation information that is observation information obtained from another business operator. When the estimated orbit range 80 of the moving object 2 (that is, the range in which the trajectory of the moving object 2 is estimated to be present) is indicated in the external prior observation information, the radio wave observation device 60 and the optical observation from the estimated orbit range 80 The range of the position where the moving object 2 is estimated to exist at the observation time of the observation by each of the devices 70 is calculated, and the observation region of the observation by each of the radio wave observation device 60 and the optical observation device 70 is determined according to the calculated range. May be. Further, when the estimated orbit range 80 of the moving object 2 is not directly indicated in the external prior observation information, the estimated orbit range 80 may be calculated from the external prior observation information.

  Subsequently, based on the prior observation information 90 a and 90 b obtained by the radio wave observation device 60 and / or the optical observation device 70, the control device 25 calculates the existence probability distribution of the moving object 2 of the moving object 2. The existence probability distribution of the moving object 2 includes the existence probability distribution of the moving object 2 at least in the first observation period (or the first observation period and the second observation period). The existence probability distribution of the moving object 2 may be a function of time.

  In the calculation of the existence probability distribution of the moving object 2, in addition to the prior observation information 90a and 90b obtained by the radio wave observation device 60 and / or the optical observation device 70, observation information obtained from other operators is used. Some external prior observation information may be used. Further, in the calculation of the existence probability distribution of the moving object 2, external advance information obtained from another operator instead of one of the prior observation information 90a and 90b obtained by the radio wave observation device 60 and the optical observation device 70. Observation information may be used. Alternatively, in the calculation of the existence probability distribution of the moving object 2, the existence probability distribution is used based on external prior observation information obtained from another operator without using the radio wave observation device 60 and the optical observation device 70. May be calculated.

  In the example shown in FIG. 27, prior observation information using the radio observation device 60 and / or the optical observation device 70 immediately before the observation of the moving object 2 using the laser device 21 (for example, within 24 hours). 90a and 90b can be acquired. When the prior observation information 90a and 90b acquired immediately before is used, it is possible to increase the estimation accuracy of the existence position of the moving object 2. Therefore, when calculating the existence probability distribution of the moving object 2 using the previous observation information 90a and 90b acquired immediately before, the spread of the existence probability distribution of the moving object 2 tends to be reduced. Therefore, in the example shown in FIG. 27, since the spread of the existence probability distribution of the moving object 2 is reduced, it is possible to narrow the scanning target range (the size of the first region 3) by the laser light 11a. As a result, the observation probability (detection probability) of the moving object 2 is improved.

(Modification)
The moving object observation system 10 in the modification includes all the components of the moving object observation system in the first embodiment. That is, the moving object observation system includes the components shown in FIG. 1 and FIG. 2A or 2B. In the above-described embodiment, the control device 25 performs the region extraction process of extracting the first region 3 based on the moving object existence probability distribution so that the total value of the moving object existence probabilities is equal to or greater than the first threshold value TH1. An example of execution has been described. On the other hand, in the modification, the control device 25 extracts the first region 3 based on the detection probability distribution of the moving object so that the total value of the detection probability of the moving object is equal to or greater than the first threshold value TH1. Execute the process. In other words, in the above description of the embodiment, if “existence probability distribution” and “existence probability” are read as “detection probability distribution” and “detection probability”, respectively, the description of the moving object observation system in the modified example It becomes.

  Even if the existence probability distribution of the moving object 2 and the existence probability distribution of the other moving object 2 are the same, the size, altitude, shape, posture, material, etc. of the moving object 2 are different from each other. When the size, altitude, shape, posture, material, and the like of 2 are different, the detection probability distribution of the moving object 2 is different from the detection probability distribution of the other moving objects 2. For this reason, the control device 25 executes region extraction processing for extracting the first region 3 based on the detection probability distribution of the moving object 2 so that the total value of detection probabilities of the moving object is equal to or greater than the first threshold value TH1. In this case, the control device 25 calculates the detection probability distribution of the moving object 2 based on the existence probability distribution of the moving object and the physical parameters (eg, size, altitude, shape, posture, material, etc.) of the moving object. What should I do? For example, the detection probability of the moving object 2 is smaller as the size of the moving object 2 is smaller. Further, the higher the height of the moving object 2, the smaller the detection probability of the moving object 2. In addition, the detection probability of the moving object 2 decreases as the RCS (Radar Cross Section) decreases according to the shape, posture, material, and the like of the moving object 2.

  The physical parameter of the moving object may be acquired based on the above-described prior observation information 90a and 90b (for example, image data of the moving object 2), or physical parameter information (for example, size information) of the plurality of moving objects 2. , Altitude information, shape information, posture information, material information, etc.) may be acquired by extracting physical parameters corresponding to the observed moving object from a storage device (not shown).

  In the moving object observation system according to the modified example, even when the RCS of the moving object 2 is small, it is possible to improve the observation probability (detection probability) of the moving object.

  The present invention is not limited to the embodiments described above, and it is obvious that the embodiments can be appropriately modified or changed within the scope of the technical idea of the present invention. Various techniques used in each embodiment or modification can be applied to other embodiments or modifications as long as no technical contradiction arises.

1: Orbit 2: Moving object 3: First region 4: Beam spot 5: Small region 6: Cell 10: Moving object observation system 10a: Main body 11a: Laser beam 11b: Reflected laser beam 21: Laser device 21a: Laser oscillator 21b : Irradiation optical system 21c: Emission direction adjustment mechanism 21d: Beam spot diameter adjustment mechanism 23: Separation mirror 24: Laser light receiving unit 25: Control device 26: Light reception optical system 60: Radio wave observation device 70: Optical observation device 80: Estimated orbit Range 90a: Prior observation information 90b: Prior observation information 103: Second region

Claims (15)

A moving object observation system for observing a moving object moving on an orbit,
A laser device configured to emit laser light;
An emission direction adjusting mechanism that adjusts an emission direction that is a direction in which the laser beam is emitted from the laser device;
A laser light receiving unit that receives reflected laser light that is reflected light of the laser light by the moving object;
And a control device,
The control device calculates the total probability of the moving object or the total detection probability of the moving object based on the first probability distribution indicating the existence probability distribution of the moving object or the detection probability distribution of the moving object. A region extraction process for extracting the first region so that the first total value shown is equal to or greater than the first threshold,
The control device transmits an emission direction adjustment command to the emission direction adjustment mechanism so that the extracted first region is scanned by the laser beam. The region extraction process includes a cell extraction process for extracting a cell from a plurality of cells in which the presence of the moving object is assumed,
The control device includes a second sum indicating a total value of the existence probabilities of the moving object or a total value of the detection probabilities of the moving object in an entire region configured by the plurality of cells extracted by the cell extraction process. The cell extraction process is repeatedly executed until a value is equal to or greater than the first threshold value,
When the second total value is equal to or greater than the first threshold, the control device ends the cell extraction process,
The moving object observation system according to claim 1, wherein the control device determines, as the first region, an entire region constituted by the plurality of cells extracted by the cell extraction processing after the cell extraction processing is completed. The control device sends an emission direction adjustment command to the emission direction adjustment mechanism so that the plurality of cells constituting the first region are scanned by the laser light in order from the cell having the high probability of existence of the moving object. The moving object observation system according to claim 1. The control device adjusts the emission direction to the emission direction adjustment mechanism so that the plurality of cells constituting the first area are scanned in an order that makes the time required for scanning the first area as short as possible. The moving object observation system according to claim 1, wherein the command is transmitted. The moving object observation according to any one of claims 1 to 4, wherein a cross section of the first region perpendicular to the traveling direction of the laser light has an elongated shape corresponding to the region having the high existence probability or the detection probability. system. The moving object observation system according to claim 5, wherein the first region is a region whose position is fixed. The size of the cross section is obtained by multiplying the area of the beam spot of the laser light when the laser light reaches the estimated trajectory of the moving object and the emission frequency indicating the number of times the laser light is emitted per unit time. The moving object observation system according to claim 6. The moving object observation system according to claim 5, wherein the first area is an area that moves with time. The size of the cross section is obtained by multiplying the area of the beam spot of the laser light when the laser light reaches the estimated trajectory of the moving object and the emission frequency indicating the number of times the laser light is emitted per unit time. The moving object observation system according to claim 8. The first area is an area that moves with time,
The moving object observation system according to any one of claims 1 to 4, wherein the shape of the first region is a thin plate shape or a linear shape extending in a direction perpendicular to the estimated trajectory of the moving object. When one axis along the direction perpendicular to the estimated trajectory of the moving object is defined as the X axis, the cell extraction process has the same position along the X axis as any of the already extracted cells. The moving object observation system according to claim 2, which is executed under a restriction condition that a cell is excluded from extraction target candidates. The moving object according to any one of claims 1 to 11, wherein the control device transmits the emission direction adjustment command to the emission direction adjustment mechanism so that the first region is repeatedly scanned by the laser light. Observation system. The control device, based on a second probability distribution indicating a presence probability distribution of the moving object or a detection probability distribution of the moving object in a second observation period different from the first observation period in which the first region is scanned, A second region extraction process for extracting a second region so that an integral value of the existence probability of the moving object or an integral value of the detection probability of the moving object is equal to or greater than a second threshold;
The moving object observation according to any one of claims 1 to 12, wherein the control device transmits the emission direction adjustment command to the emission direction adjustment mechanism so that the second region is scanned by the laser beam. system. The moving object observation system according to claim 13, wherein the second probability distribution is a probability distribution calculated by reflecting an observation result of the moving object in the first observation period. A moving object observation method for observing a moving object moving on an orbit,
Obtaining a first probability distribution indicating a presence probability distribution of the moving object or a detection probability distribution of the moving object in a first observation period;
Extracting a first region based on the first probability distribution such that the total value of the existence probability of the moving object or the total value of the detection probability of the moving object is equal to or greater than a first threshold;
Emitting laser light so that the first region is scanned by laser light;
Detecting the moving object by receiving reflected laser light that is reflected light of the laser light by the moving object.

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