Flight control device, flight control method, and unmanned aerial vehicle

Abstract

To provide a flight control device, a flight control method, and an unmanned aerial vehicle capable of safely controlling the flight of the unmanned aerial vehicle even in a place where there are a lot of shields.SOLUTION: A UAV 1 continuously acquires parameter values that serve as an indicator of positioning accuracy as information regarding a positioning satellite based on information on a radio waves from the positioning satellite captured during flight, and, when the acquired parameter values correspond to a situation indicating a decrease in positioning accuracy, identifies shields that interrupt the reception of the radio wave in the vicinity of the UAV 1 and controls flight to move away from the identified shields.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aircraft that receive radio waves from positioning satellites and fly autonomously.

Background Art

[0002] Conventionally, in unmanned aircraft such as drones, autonomous flight using a satellite positioning system has been the mainstream, and how to achieve autonomous flight has been a problem in an environment where positioning satellites cannot be captured. For example, Patent Document 1 discloses a technique that, even when the positioning accuracy decreases when flying along a planned route, avoids the decrease in positioning accuracy by flying the unmanned aircraft along a route different from the planned route and continues to fly the unmanned aircraft while measuring the position.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] By the way, in places with many obstacles that obstruct the reception of radio waves from positioning satellites, especially in urban areas where the use of drone delivery is expected in the future, it is expected that buildings (for example, high-rise buildings) will be densely packed, so the number of positioning satellites captured will decrease, resulting in a decrease in positioning accuracy, and there are concerns about a decrease in the safety of the aircraft and the impact on delivery. In addition, the positioning accuracy also decreases due to changes in the arrangement state of positioning satellites moving around the earth, and there are concerns about the safety of the aircraft and the impact on delivery.

[0005] Therefore, an example of an object of the present invention is to provide a flight control device, a flight control method, and an unmanned aircraft that can safely perform flight control of an unmanned aircraft even in a place with many obstacles.

Means for Solving the Problems

[0006] (Application Example 1) To solve the above problems, the flight control device according to this application example includes an acquisition unit that continuously acquires, as information on the positioning satellite, a parameter value that is an index of positioning accuracy based on information on radio waves from positioning satellites captured by an unmanned aircraft during flight, a specifying unit that specifies an obstacle that obstructs the reception of the radio waves in the vicinity of the unmanned aircraft during flight when the parameter value corresponds to a situation indicating a decrease in the positioning accuracy, and a flight control unit that performs flight control of the unmanned aircraft so as to move away from the specified obstacle.

[0007] (Application Example 2) The flight control method according to this application example is a flight control method executed by a computer, and includes a step of continuously acquiring, as information on the positioning satellite, a parameter value that is an index of positioning accuracy based on information on radio waves from positioning satellites captured by an unmanned aircraft during flight, a step of specifying an obstacle that obstructs the reception of the radio waves in the vicinity of the unmanned aircraft during flight when the parameter value corresponds to a situation indicating a decrease in the positioning accuracy, and a step of performing flight control of the unmanned aircraft so as to move away from the specified obstacle.

[0008] (Application Example 3) The unmanned aircraft according to this application example is an unmanned aircraft capable of autonomous flight, and includes an acquisition unit that continuously acquires, as information on the positioning satellite, a parameter value that is an index of positioning accuracy based on information on radio waves from positioning satellites captured during flight, a specifying unit that specifies an obstacle that obstructs the reception of the radio waves in the vicinity of the unmanned aircraft during flight when the parameter value corresponds to a situation indicating a decrease in the positioning accuracy, and a flight control unit that performs flight control so that the unmanned aircraft moves away from the specified obstacle.

Advantages of the Invention

[0009] According to the present invention, it is possible to safely perform flight control of an unmanned aircraft even in a location with many obstacles.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The embodiment described below is an embodiment when the present invention is applied to a flight control system that controls the flight of an unmanned aerial vehicle (hereinafter referred to as UAV (Unmanned Aerial Vehicle)) capable of autonomous flight by receiving radio waves from positioning satellites.

[0012] 1. Configuration and Operational Overview of Flight Control System S First, referring to FIG. 1, the configuration and operation overview of the flight control system S according to this embodiment will be described. FIG. 1 is a diagram showing an example of the schematic configuration of the flight control system S. As shown in FIG. 1, the flight control system S includes a UAV 1 and a flight management server 2, etc. The UAV 1 is also called a drone or a multicopter. In the example of FIG. 1, one UAV 1 is shown, but actually there are a plurality of UAV 1s. The UAV 1 can take off according to a takeoff instruction from a GCS (Ground Control Station) and fly autonomously, and is used, for example, for delivery, surveying, photography, monitoring, etc. Note that the UAV 1 can also fly according to remote control from the ground by a control terminal (not shown) equipped with a GCS. The flight management server 2 is a server that manages the flight route and flight schedule of the UAV 1 and can also perform flight control of the UAV 1. The UAV 1 and the flight management server 2 are each connected to a communication network NW. The communication network NW is composed of, for example, the Internet, a mobile communication network, and its radio base stations, etc.

[0013] 1-1. Configuration and Functions of UAV1 Next, referring to FIG. 2, the configuration and functions of the UAV 1 will be described. FIG. 2 is a diagram showing an example of the schematic configuration of the UAV 1. As shown in FIG. 2, the UAV 1 includes a drive unit 11, a positioning unit 12, a communication unit 13, a sensor unit 14, a storage unit 15, and a control unit 16 (an example of a flight control device), etc., and includes a battery (not shown) that supplies power to these respective units. Also, as shown in FIG. 1, the UAV 1 includes a rotor (propeller) 1a that is a horizontal rotating wing, and a holding member 1b that holds an article to be loaded (for example, a delivery item), etc. The drive unit 11 includes a motor and a rotating shaft, etc. The drive unit 11 rotates a plurality of rotors 1a by a motor and a rotating shaft, etc. that are driven according to a control signal output from the control unit 16.

[0014] ​​​​The positioning unit 12 includes a radio wave receiver and the like. The positioning unit 12 receives radio waves transmitted from a plurality of positioning satellites of GNSS (Global Navigation Satellite System) by means of a radio wave receiver, and detects the current position of the UAV 1 based on the radio waves. The current position of the UAV 1 may be represented by the latitude and longitude of the UAV 1 (that is, two-dimensional coordinates), or may be represented by the latitude, longitude, and altitude of the UAV 1 (that is, three-dimensional coordinates). Here, the altitude detected by the positioning unit 12 is the height from the ellipsoid of revolution defined in a world geodetic system such as WGS (World Geodetic System) 84. Such altitude may be interpolated to a value indicating the height from the ground in the area where the UAV 1 flies by known interpolation calculations. Note that the positioning satellites may include satellites used by a plurality of satellite positioning systems such as GPS (Global Positioning System) satellites, Michibiki satellites, and Galileo satellites. The current position detected by the positioning unit 12 is continuously output to the control unit 16. At this time, information on radio waves from the positioning satellites captured by the positioning unit 12 (for example, the intensity and reception angle of the radio waves) is continuously output to the control unit 16.

[0015] The communication unit 13 has a wireless communication function and is responsible for controlling communication performed via the communication network NW. The sensor unit 14 includes various sensors used for flight control of the UAV 1 and the like. The various sensors include, for example, an optical sensor, a three-axis angular velocity sensor, a three-axis acceleration sensor, and a geomagnetic sensor. The optical sensor is configured to include a camera (for example, an RGB camera, an infrared camera), and continuously images the real space within the range of the angle of view of the camera. Note that the optical sensor may include a LiDAR (Light Detection and Ranging, or Laser Imaging Detection and Ranging) sensor that measures the shape of a ground object and the distance to the ground object. The sensing information detected by the sensor unit 14 is continuously output to the control unit 16.

[0016] The storage unit 15 is composed of a non-volatile memory or the like, and stores various programs (program code groups) and data including an operating system and applications. Here, the applications include a program for executing a flight control method. Further, the storage unit 15 stores the aircraft ID of the UAV1. The aircraft ID of the UAV1 is identification information for identifying the UAV1. The control unit 16 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. Note that the CPU may be a general-purpose processor, an application-specific processor, or a processor including transistors and other integrated circuits (electric circuits and electronic circuits).

[0017] Figure 3 is a diagram showing an example of a functional block in the control unit 16. The control unit 16 (CPU) functions as, for example, a satellite information acquisition unit 161 (an example of an acquisition unit), an obstacle identification unit 162 (an example of an identification unit), a flight control unit 163, etc., as shown in Figure 3, according to a program (program code group) stored in the ROM or the storage unit 15. Note that the control unit 16 sequentially transmits the position information indicating the current position of the UAV1 to the flight management server 2 via the communication unit 13 together with the aircraft ID of the UAV1.

[0018] The satellite information acquisition unit 161 continuously acquires, as information on the positioning satellite, a parameter value that is an index of positioning accuracy based on the radio wave information from the positioning satellite captured by the positioning unit 12 while the UAV 1 is in flight. Here, examples of the parameter value include the number of captured positioning satellites and the rate of decrease in positioning accuracy (hereinafter referred to as "DOP (Dilution of Precision)"). The DOP is calculated, for example, by substituting the current position of the UAV 1 and the elevation angle and azimuth angle of the captured positioning satellite into a predetermined matrix. The elevation angle and azimuth angle of the positioning satellite can be specified from the radio wave information from the positioning satellite. The DOP depends on the arrangement state (for example, bias) of the positioning satellites, and the smaller the DOP, the higher the positioning accuracy. Note that the DOP includes an HDOP indicating the rate of decrease in positioning accuracy in the horizontal direction and a VDOP indicating the rate of decrease in positioning accuracy in the vertical direction, etc., and either both the HDOP and the VDOP or one of them is used. When both the HDOP and the VDOP are used, for example, the maximum value of the HDOP and the VDOP (or the average value of the HDOP and the VDOP may also be used) may be used as the DOP.

[0019] The shielding object specific unit 162 continuously checks whether the parameter value (for example, the change in the parameter value) acquired by the satellite information acquisition unit 161 corresponds to a situation (in other words, a criterion) indicating a decrease in positioning accuracy. When it corresponds to a situation indicating a decrease in positioning accuracy (hereinafter, also appropriately referred to as "when the positioning accuracy has decreased"), it identifies (in other words, estimates a shielding object that is expected to interfere with the reception of radio waves) a shielding object that interferes with the reception of radio waves in the vicinity of the flying UAV 1. Such a situation is preset for each parameter value. For example, when the parameter value is the number of captured positioning satellites, the shielding object specific unit 162 continuously compares the number of captures continuously acquired by the satellite information acquisition unit 161 with a first threshold value (for example, 4) (an example of the above check), and when the number of captures is less than the first threshold value, it determines that it corresponds to a situation indicating a decrease in positioning accuracy, and identifies a shielding object that interferes with the reception of the radio waves in the vicinity of UAV 1. Thereby, the shielding object can be identified more accurately. Alternatively, when the parameter value is DOP, the shielding object specific unit 162 continuously compares the DOP continuously acquired by the satellite information acquisition unit 161 with a second threshold value (for example, 4) (an example of the above check), and when the DOP becomes larger than the second threshold value, it may identify a shielding object that interferes with the reception of the radio waves in the vicinity of UAV 1 on the assumption that it corresponds to a situation indicating a decrease in positioning accuracy. Also by this, the shielding object can be identified more accurately. Note that the first threshold value, the second threshold value, etc. are preset by a system administrator or the like.

[0020] Here, the periphery of the UAV1 may be, for example, within a predetermined range (e.g., within a radius of 500 m centered on the current position of the UAV1) with reference to the current position of the UAV1. When specifying the above-mentioned obstacle, the obstacle specifying unit 162 may, for example, acquire from the flight management server 2 the ground object information including the horizontal positions (latitude and longitude) and heights (values indicating heights) of one or more ground objects existing in the periphery of the UAV1 during flight, and specify the obstacle based on the ground object information. For example, the obstacle specifying unit 162 may specify the heights of one or more ground objects from the acquired ground object information, and specify as an obstacle the ground object whose specified height is equal to or higher than a predetermined height (e.g., 20 m). Thereby, the obstacle can be specified more appropriately. Alternatively, the obstacle specifying unit 162 may specify the horizontal positions and heights of one or more ground objects from the acquired ground object information, and specify as an obstacle the ground object whose distance from the current position of the UAV1 to the specified horizontal position is within a predetermined distance (e.g., within 50 m) and whose specified height is equal to or higher than a predetermined height. Further, the obstacle specifying unit 162 may acquire from the flight management server 2 the map data of the periphery of the UAV1 during flight, and acquire the above-mentioned ground object information from the map data. Thereby, the obstacle can be specified more efficiently.

[0021] The flight control unit 163 performs flight control (including takeoff control and landing control) of the UAV1 using the current position detected by the positioning unit 12, the sensing information acquired from the sensor unit 14, the flight control information, and the like. In such flight control, the rotation speed of the rotor 1a, the position, attitude, and traveling direction of the UAV1 are controlled. The flight control information is acquired, for example, from the flight management server 2. The flight control information includes, for example, a predetermined flight route and a flight schedule from the departure point to the destination point (e.g., the delivery destination of the article). The flight route may be represented, for example, by the latitude and longitude of each of a plurality of waypoints (an example of a predetermined point) on the flight route, or may be represented by the latitude, longitude, and altitude of each of the waypoints. The flight schedule includes, for example, the scheduled departure time of the UAV1 from the departure point and the scheduled arrival time at the destination point, and may include the scheduled passing time for passing through each waypoint.

[0022] Furthermore, the flight control unit 163 performs flight control of the UAV 1 during flight so that the UAV 1 moves away from the obstacle identified by the obstacle identification unit 162. For example, the flight control unit 163 moves the UAV 1 in a direction in which the decrease in positioning accuracy is recovered. Here, the direction in which the decrease in positioning accuracy is recovered is, for example, a direction in which the number of captured positioning satellites becomes equal to or greater than a first threshold value, or a direction in which the DOP becomes equal to or less than a second threshold value. Such a direction may be a horizontal direction, but it is desirable that it is a direction in which the UAV 1 ascends at a predetermined ascending angle θ (0 degrees < θ ≤ 90 degrees) (that is, increases the altitude of the UAV 1).

[0023] For example, when the value obtained by subtracting (subtracting) the current altitude of the UAV 1 (the value indicating the interpolated altitude) from the height of the obstacle (for example, the maximum value) identified by the obstacle identification unit 162 is 0 or more and equal to or less than a third threshold value, the flight control unit 163 may perform flight control of the UAV 1 so that the UAV 1 ascends in the vertical direction. FIG. 4 is a conceptual diagram showing how the UAV 1 ascends in the vertical direction (θ = 90 degrees). In the example of FIG. 4, since the value obtained by subtracting the altitude of the UAV 1 (for example, 10 m) from the height of the obstacle OB1 (for example, 30 m) identified by the obstacle identification unit 162 (for example, 20 m) is 0 m or more and equal to or less than the third threshold value (for example, 30 m), the flight control unit 163 performs flight control of the UAV 1 so that the UAV 1 ascends in the vertical direction (θ = 90 degrees) (for example, ascends at an ascending speed of 4 m / s). As a result, it is possible to recover more quickly from the decrease in positioning accuracy. In the example of FIG. 4, the UAV 1 ascends 20 m and passes over the obstacle OB1 (that is, is positioned at a height equal to or greater than the height of the obstacle OB1). At this time, the flight control unit 163 may determine up to what altitude (in other words, how far to ascend) based on the current altitude of the UAV 1 and the height of the obstacle OB1.

[0024] Alternatively, when the height of the obstacle identified by the obstacle identification unit 162 is equal to or less than a third threshold value (e.g., 40 m), the flight control unit 163 may perform flight control of the UAV 1 so that the UAV 1 ascends in the vertical direction. By doing so, it is also possible to more quickly recover from the degradation of the positioning accuracy. In this case, in the example of FIG. 4, since the height of the obstacle OB1 identified by the obstacle identification unit 162 (e.g., 30 m) is equal to or less than the third threshold value (e.g., 40 m), the UAV 1 is flight-controlled to ascend in the vertical direction. Note that when the height of the obstacle OB1 is equal to or less than the third threshold value, the flight control unit 163 may perform flight control of the UAV 1 so that the UAV 1 ascends at a predetermined ascending angle on the flight route (a two-dimensional route excluding height). Thereby, only the altitude is changed on the flight route, so that, for example, when there is only one obstacle, the UAV 1 can fly through the obstacle, and it can be expected that the UAV 1 will recover from the degradation of the positioning accuracy earlier than when ascending vertically.

[0025] On the other hand, when the value obtained by subtracting the current altitude of the UAV 1 from the height of the obstacle identified by the obstacle identification unit 162 is greater than a third threshold value (e.g., 30 m), the flight control unit 163 may perform flight control of the UAV 1 so that the UAV 1 moves away from the obstacle in the horizontal direction (i.e., including the diagonally upward direction) while ascending. FIG. 5 is a conceptual diagram showing a state in which the UAV 1 ascends in the diagonally upward direction (0 degrees < θ < 90 degrees). In the example of FIG. 5, since the value obtained by subtracting the altitude of the UAV 1 (e.g., 10 m) from the height of the obstacle OB2 identified by the obstacle identification unit 162 (e.g., 70 m) (e.g., 60 m) is greater than the third threshold value (e.g., 30 m), the flight control unit 163 performs flight control of the UAV 1 so that the UAV 1 moves away from the obstacle OB2 in the horizontal direction while ascending. Thereby, even when the obstacle OB2 that obstructs the reception of radio waves from the positioning satellite is high, it is possible to more quickly recover from the degradation of the positioning accuracy. Note that in the example of FIG. 5, when the altitude of the UAV 1 is 50 m, since the value obtained by subtracting the current altitude of the UAV 1 from the height of the obstacle (e.g., 70 m) (e.g., 20 m) is equal to or less than the third threshold value (e.g., 30 m), the UAV 1 is flight-controlled to ascend in the vertical direction.

[0026] Alternatively, when the height of the obstacle identified by the obstacle identification unit 162 is greater than a third threshold value (e.g., 40 m), the flight control unit 163 may perform flight control of the UAV 1 so that the UAV 1 moves away horizontally from the obstacle while ascending. Also by this, it is possible to recover more quickly from the decrease in positioning accuracy. In this case, in the example of FIG. 5, since the height (e.g., 70 m) of the obstacle OB2 identified by the obstacle identification unit 162 is greater than the third threshold value (e.g., 40 m), the UAV 1 will be flight-controlled to move away horizontally from the obstacle OB2 while ascending.

[0027] Also, as described above, when the UAV 1 moves away horizontally from the obstacle while ascending, the flight control unit 163 may determine whether there is another obstacle in the direction away from the obstacle identified by the obstacle identification unit 162. Then, when it is determined that there is another obstacle, the flight control unit 163 may calculate an ascending angle at which the UAV 1 does not collide with the other obstacle, and perform flight control of the UAV 1 so as to ascend at the calculated ascending angle. Thereby, it is possible to recover more safely from the decrease in positioning accuracy.

[0028] FIG. 6 is a conceptual diagram showing a state in which the UAV 1 ascends at an ascending angle that does not collide with another obstacle OB3 on the opposite side of the obstacle OB2. Alternatively, when it is determined that there is another obstacle in the direction away from the obstacle, the flight control unit 163 may perform flight control of the UAV 1 so as to ascend through the central portion between the two obstacles. Also by this, it is possible to recover more safely from the decrease in positioning accuracy. FIG. 7 is a conceptual diagram showing an example of the central portion between the obstacle OB2 and the obstacle OB3. Here, the central portion means, for example, the central region when the region between the obstacle OB2 and the obstacle OB3 is divided into a region close to the obstacle OB2, a region close to the obstacle OB3, and a central region. Such a central portion may vary according to the distance between the obstacle OB2 and the obstacle OB3.

[0029] Further, when the flight control unit 163 determines that the decrease in positioning accuracy is recovered by the ascent of the UAV 1 according to flight control (for example, when the number of captured positioning satellites becomes equal to or greater than the first threshold value, or when the DOP becomes equal to or less than the second threshold value), the flight control unit 163 may perform flight control of the UAV 1 so that the UAV 1 gradually descends to the next waypoint (an example of a predetermined point) that the UAV 1 should aim for. Thereby, the UAV 1 can be more safely returned to the original flight route before ascent.

[0030] FIG. 8 is a conceptual diagram showing a state in which the UAV 1 gradually descends to the waypoint WP3 after the decrease in positioning accuracy is recovered. In the example of FIG. 8, the flight route RO passing through the waypoints WP1 to WP4 is a preset flight route. The example of FIG. 8 shows that the situation corresponds to the decrease in positioning accuracy at the waypoint WP1. As shown in FIG. 8, when the UAV 1 ascends and temporarily deviates from the flight route RO and the decrease in positioning accuracy is recovered at the point P0, the UAV 1 gradually descends to the next waypoint WP3 that it should aim for, and when it reaches the waypoint WP3, it returns to the flight route RO again. In the example of FIG. 8, since the UAV 1 gradually descends, it will fly toward the waypoint WP3 instead of the waypoint WP2. That is, in this case, the flight control unit 163 determines the next waypoint WP3 to be aimed for based on a predetermined descent angle for gradual descent.

[0031] Alternatively, the flight control unit 163 may identify a waypoint among the waypoints scheduled to be passed through in the flight route of the UAV 1, where the degradation of the positioning accuracy is expected to recover, and fly the UAV 1 towards the identified waypoint while avoiding the obstacles identified by the obstacle identification unit 162. Thereby, it is possible to more quickly return to the original flight route and recover from the degradation of the positioning accuracy. For example, the flight control unit 163 acquires from the flight management server 2 satellite information indicating the predicted number of positioning satellites that can be captured at each waypoint scheduled to be passed through in the flight route, or the predicted DOP at each waypoint. Then, based on the acquired satellite information, the flight control unit 163 identifies a waypoint where the predicted number of positioning satellites is expected to be equal to or greater than a first threshold value (e.g., 4), or a waypoint where the predicted DOP is expected to be equal to or less than a second threshold value (e.g., 4), as a waypoint where the degradation of the positioning accuracy is expected to recover. Thereby, it is possible to more accurately identify a waypoint where the degradation of the positioning accuracy is expected to recover.

[0032] Alternatively, the flight control unit 163 may set a fourth threshold value (e.g., 5) greater than the first threshold value (e.g., 4), or a fifth threshold value (e.g., 3) smaller than the second threshold value (e.g., 4). In this case, based on the acquired satellite information, the flight control unit 163 identifies a waypoint where the predicted number of positioning satellites is equal to or greater than the fourth threshold value (e.g., 5), or a waypoint where the predicted DOP is equal to or less than the fifth threshold value (e.g., 3), as a waypoint where the degradation of the positioning accuracy is expected to recover. Thereby, even if the point corresponding to the situation indicating the degradation of the positioning accuracy is immediately before the next waypoint to be headed (i.e., when the distance between the point and the waypoint is as short as several meters), it is possible to more safely recover from the degradation of the positioning accuracy. Note that the setting of the fourth threshold value or the fifth threshold value may be performed when the remaining battery level of the UAV 1 is more than the battery level required to reach the destination point.

[0033] FIG. 9 is a conceptual diagram showing a state in which the UAV 1 flies toward a waypoint WP3 where a decrease in positioning accuracy is expected to recover. In the example of FIG. 9, at a point P1 on the way toward the waypoint WP2, for example, when the number of positioning satellites captured becomes less than the first threshold, the waypoint WP3 is specified. Therefore, instead of (skipping) the waypoint WP2, it shows that the UAV 1 starts to fly toward the waypoint WP3. Here, the waypoint WP3 may be, for example, a waypoint where the predicted number of positioning satellites captured is equal to or greater than a fourth threshold that is greater than the first threshold, or a waypoint where the predicted DOP is equal to or greater than a fifth threshold that is less than the second threshold.

[0034] 1-2. Configuration and Functions of Flight Management Server 2 Next, with reference to FIG. 10, the configuration and functions of the flight management server 2 will be described. FIG. 10 is a diagram showing a schematic configuration example of the flight management server 2. As shown in FIG. 10, the flight management server 2 includes a communication unit 21, a storage unit 22, a control unit 23, and the like. The communication unit 21 is responsible for controlling communication performed via the communication network NW. Thereby, the flight management server 2 can communicate with the UAV 1. The position information transmitted from the UAV 1 is received by the communication unit 21. Thereby, the flight management server 2 can recognize the current position of the UAV 1. Further, the delivery control server 2 can communicate via the communication network NW with a satellite orbit management server (not shown) that manages the orbits of a plurality of positioning satellites moving around the earth. Thereby, the delivery control server 2 receives orbit information indicating the orbits of the plurality of positioning satellites from the satellite orbit management server. The orbit information indicates, for example, the satellite positions and times on the orbits of the positioning satellites predicted 24 to 48 hours ago. Such satellite positions are satellite positions at future times and are represented by, for example, latitude, longitude, and altitude.

[0035] ​​The storage unit 22 is composed of, for example, a hard disk drive or the like, and stores various programs including an operating system and applications. Further, the storage unit 22 stores map data of the flight area of the UAV 1. The map data includes information indicating the horizontal position, height, and width (area) of artificial objects such as buildings installed in the flight area. Note that the map data may include information indicating the position, height, and width of natural objects such as trees, mountains, and hills existing in the flight area. Furthermore, an aircraft management database 221 (DB) or the like is constructed in the storage unit 22. The aircraft management database 221 is a database for managing information related to the UAV 1. In the aircraft management database 221, for example, an aircraft ID, a flight route, a flight schedule, etc. are stored in association with each UAV 1.

[0036] The control unit 23 includes a CPU, a ROM, a RAM, etc. The control unit 23 transmits flight control information including the flight route and flight schedule of the UAV 1 to the UAV 1 via the communication unit 21. Further, the control unit 23 transmits feature information or map data including the horizontal position and height of features existing around the current position of the UAV 1 to the UAV 1 via the communication unit 21. Also, the control unit 23 calculates the predicted number of positioning satellites that can be captured at each of a plurality of waypoints on the flight route based on the position of each waypoint (for example, three-dimensional coordinates) and the orbit information (for example, satellite positions at the passing times of each waypoint) obtained from the satellite orbit management server. Further, the control unit 23 may calculate the predicted DOP at each of a plurality of waypoints on the flight route based on the position of each waypoint and the orbit information obtained from the satellite orbit management server. Then, the control unit 23 may transmit satellite information indicating the calculated predicted number of positioning satellites that can be captured at each waypoint or the predicted DOP at each waypoint to the UAV 1 via the communication unit 21. Note that the control unit 23 may perform flight control of the UAV 1 in cooperation with the control unit 16 of the UAV 1. In this case, the control unit 23 transmits a flight control command for controlling the traveling direction of the UAV 1 to the UAV 1 via the communication unit 21.

[0037] 2. Operation of Flight Control System S Next, the operation of the flight control system S according to the present embodiment will be described separately in Example 1 and Example 2.

[0038] (Example 1) First, with reference to FIG. 11, the operation of the flight control system S according to Example 1 will be described. FIG. 11 is a flowchart showing an example of flight control processing executed by the control unit 23 of the flight management server 2 in Example 1. The processing shown in FIG. 11 is started, for example, when the UAV 1 starts flying from the departure point. When the UAV 1 starts flying, basically, it flies along each waypoint on the flight route described above. When the processing shown in FIG. 11 is started, the control unit 16 acquires, based on the radio wave information from the positioning satellites captured by the positioning unit 12, a parameter value (for example, the number of captured positioning satellites or DOP) that is an index of the positioning accuracy, by the satellite information acquisition unit 161 (step S1).

[0039] Next, the control unit 16 determines whether the parameter value acquired in step S1 corresponds to a situation indicating a decrease in positioning accuracy (step S2). For example, the obstacle identification unit 162 compares the number of captures acquired in step S1 with the first threshold value and determines whether the number of captures is less than the first threshold value. Alternatively, the obstacle identification unit 162 compares the DOP acquired in step S1 with the second threshold value and determines whether the DOP is greater than the second threshold value. When it is determined that the parameter value does not correspond to a situation indicating a decrease in positioning accuracy (for example, the number of captures is not less than the first threshold value, or the DOP is not greater than the second threshold value) (step S2: NO), the process proceeds to step S3. On the other hand, when it is determined that the parameter value corresponds to a situation indicating a decrease in positioning accuracy (for example, the number of captures is less than the first threshold value, or the DOP is greater than the second threshold value) (step S2: YES), the process proceeds to step S4.

[0040] ​​Note that in step S2, instead of comparing the number of captures with the first threshold value, the shielding object identification unit 162 determines whether a value obtained by subtracting the number of captures obtained in the current step S1 (e.g., 4) from the number of captures obtained in the previous step S1 (e.g., 5) is equal to or greater than a threshold value (a positive value, e.g., 1). If the value is equal to or greater than the threshold value (i.e., when the number of captures has decreased), the process may proceed to step S4. Alternatively, instead of comparing the DOP with the second threshold value, the shielding object identification unit 162 determines whether a value obtained by subtracting the DOP obtained in the previous step S1 (e.g., 3) from the DOP obtained in the current step S1 (e.g., 4) is equal to or greater than a threshold value (a positive value: e.g., 1). If the value is equal to or greater than the threshold value (i.e., when the ODP has increased), the process may proceed to step S4.

[0041] In step S3, the control unit 16 determines whether UAV1 has reached the target point. If it is determined that UAV1 has not reached the target point (step S3: NO), the process returns to step S1. On the other hand, if it is determined that UAV1 has reached the target point (step S3: YES), the process shown in FIG. 11 ends. After the process shown in FIG. 11 ends, UAV1 lands according to the landing control by the control unit 16. Alternatively, UAV1 hovers according to the hovering control by the control unit 16 while dropping an article.

[0042] In step S4, the control unit 16 acquires feature information including the horizontal position and height of features existing around the flying UAV1. Here, the feature information may be acquired (stored in the storage unit 15) from the flight management server 2 before the start of the process shown in FIG. 11, or may be acquired by requesting the flight management server 2 in step S4. Note that map data including the feature information may be acquired. Next, based on the feature information acquired in step S4, as described above, the control unit 16 specifies, by the shielding object specifying unit 162, a shielding object that obstructs the reception of radio waves from the positioning satellite around the UAV1 (step S5). At this time, it is preferable that the horizontal position and height of the shielding object are specified. Note that a plurality of shielding objects may be specified in step S5, and in this case, in the following process, the plurality of shielding objects may be processed as a single shielding object.

[0043] Next, the control unit 16 acquires the current altitude of the UAV1 (a value indicating the interpolated altitude) from the altitude measuring unit 12, and determines whether a value obtained by subtracting the current altitude of the UAV1 from the height of the shielding object specified in step S5 (for example, the maximum value) is equal to or less than a third threshold (step S6). If it is determined that the value obtained by subtracting the current altitude of the UAV1 from the height of the shielding object is equal to or less than the third threshold (step S6: YES), the process proceeds to step S7. On the other hand, if it is determined that the value obtained by subtracting the current altitude of the UAV1 from the height of the shielding object is not equal to or less than the third threshold (step S6: NO), the process proceeds to step S10. Note that even if it is determined that the value obtained by subtracting the current altitude of the UAV1 from the height of the shielding object is not equal to or less than the third threshold, if the distance between the horizontal position of the UAV1 and the horizontal position of the shielding object is separated by a predetermined distance (for example, 20 m) or more, the process may proceed to step S7.

[0044] As another example of step S6 above, it may be determined whether the height of the shielding object (for example, the maximum value) specified in step S5 is equal to or less than a third threshold value. And when it is determined that the height of the shielding object is equal to or less than the third threshold value (step S6: YES), the process proceeds to step S7. On the other hand, when it is determined that the height of the shielding object is not equal to or less than the third threshold value (step S6: NO), the process proceeds to step S10. Note that even when the height of the shielding object is higher than the third threshold value, if the distance between the horizontal position of UAV1 and the horizontal position of the shielding object is separated by a predetermined distance (for example, 20 m) or more, the process may proceed to step S7.

[0045] In step S7, the control unit 16 executes flight control of UAV1 so that UAV1 ascends by a predetermined distance (for example, 5 m) in the vertical direction. Next, the control unit 16 obtains a parameter value that is an index of positioning accuracy based on the radio wave information from the positioning satellites captured by the positioning unit 12 in the same manner as in step S1 (step S8). Next, the control unit 16 determines whether the parameter value obtained in step S8 corresponds to a situation indicating a decrease in positioning accuracy (step S9). When it is determined that the parameter value does not correspond to a situation indicating a decrease in positioning accuracy (that is, the decrease in positioning accuracy has recovered) (step S9: NO), the process proceeds to step S16. On the other hand, when it is determined that the parameter value corresponds to a situation indicating a decrease in positioning accuracy (step S9: YES), the process returns to step S7.

[0046] Note that in step S7 above, the control unit 16 may execute flight control of UAV1 so that it ascends by a distance corresponding to the value obtained by subtracting the current altitude of UAV1 (the interpolated altitude) from the height of the shielding object (for example, the distance to the position corresponding to the height of the shielding object). In this case, the control unit 16 may skip the processes of steps S8 and S9 and shift to step S16.

[0047] In step S10, the control unit 16 determines whether there is another obstacle in the direction away from the obstacle identified in step S5. If it is determined that there is no other obstacle (step S10: NO), the standard ascent angle is set (step S11), and the process proceeds to step S13. On the other hand, if it is determined that there is another obstacle (step S10: YES), the process proceeds to step S12. In step S12, the control unit 16 calculates and sets the ascent angle at which the UAV1 will not collide with the other obstacle, and advances the process to step S13. For example, based on the horizontal position of the UAV1, the horizontal position and height of the other obstacle, the ascent angle at which the UAV1 will not collide with the other obstacle is calculated.

[0048] In step S13, the control unit 16 performs flight control of the UAV1 so that the UAV1 ascends by a predetermined distance at the ascent angle set in step S11 or step S12. Then, the control unit 16, similar to step S1, acquires a parameter value that is an index of positioning accuracy based on the radio wave information from the positioning satellites captured by the positioning unit 12 (step S14). Next, the control unit 16 determines whether the parameter value acquired in step S14 corresponds to a situation indicating a decrease in positioning accuracy (step S15). If it is determined that the parameter value does not correspond to a situation indicating a decrease in positioning accuracy (that is, the decrease in positioning accuracy has recovered) (step S15: NO), the process proceeds to step S16. On the other hand, if it is determined that the parameter value corresponds to a situation indicating a decrease in positioning accuracy (step S15: YES), the process returns to step S13.

[0049] In step S16, the control unit 16 executes flight control of the UAV1 so that the UAV1 gradually descends to the next waypoint it should aim for. When the UAV1 reaches the next waypoint it should aim for (that is, when it returns to the original flight route), the UAV1 is flight-controlled to fly following each waypoint on the flight route. Next, the control unit 16, in the same manner as in step S1, obtains a parameter value that is an index of the positioning accuracy based on the radio wave information from the positioning satellites captured by the positioning unit 12 (step S17). Next, the control unit 16 determines whether the parameter value obtained in step S17 corresponds to a situation indicating a decrease in the positioning accuracy (step S18).

[0050] And when it is determined that the parameter value corresponds to a situation indicating a decrease in the positioning accuracy (for example, the capture count is less than the first threshold value, or the DOP is greater than the second threshold value) (step S18: YES), the process returns to step S4, and the same processing as above is performed. On the other hand, when it is determined that the parameter value does not correspond to a situation indicating a decrease in the positioning accuracy (for example, the capture count is not less than the first threshold value, or the DOP is not greater than the second threshold value) (step S18: NO), it is determined whether the UAV1 has reached the destination point (step S19). When it is determined that the UAV1 has not reached the destination point (step S19: NO), the process returns to step S17, and the processes of steps S17 and S18 are performed. On the other hand, when it is determined that the UAV1 has reached the destination point (step S19: YES), the process shown in FIG. 11 ends.

[0051] (Example 2) Next, with reference to FIG. 12, the operation of the flight control system S according to the second embodiment will be described. FIG. 12 is a flowchart showing an example of the flight control process executed by the control unit 23 of the flight management server 2 in the second embodiment. The process shown in FIG. 12 is started, for example, when the UAV 1 starts flying from the starting point. When the UAV 1 starts flying, it flies along each waypoint on the flight route in the same manner as in the first embodiment. When the process shown in FIG. 12 is started, the control unit 16 acquires, based on the radio wave information from the positioning satellites captured by the positioning unit 12, a parameter value (for example, the number of captured positioning satellites or DOP) that is an index of the positioning accuracy, by the satellite information acquisition unit 161 (step S21).

[0052] Next, the control unit 16 determines whether the parameter value acquired in step S21 corresponds to a situation indicating a decrease in positioning accuracy (step S22). If it is determined that the parameter value does not correspond to a situation indicating a decrease in positioning accuracy (for example, the number of captures is not less than the first threshold, or the DOP is not greater than the second threshold) (step S22: NO), the process proceeds to step S23. On the other hand, if it is determined that the parameter value corresponds to a situation indicating a decrease in positioning accuracy (for example, the number of captures is less than the first threshold, or the DOP is greater than the second threshold) (step S22: YES), the process proceeds to step S24. In step S22, similar to step S2, it may be determined whether the value obtained by subtracting the number of captures acquired in the current step S21 from the number of captures acquired in the previous step S21 is equal to or greater than the threshold. Alternatively, it may be determined whether the DOP acquired in the current step S21 minus the DOP acquired in the previous step S21 is equal to or greater than the threshold.

[0053] In step S23, the control unit 16 determines whether UAV1 has reached the destination point. If it is determined that UAV1 has not reached the destination point (step S23: NO), the process returns to step S21. On the other hand, if it is determined that UAV1 has reached the destination point (step S23: YES), the process shown in FIG. 12 ends. In step S24, similar to step S4, feature information including the horizontal position and height of features existing around the flying UAV1 is acquired. Then, based on the feature information acquired in step S24, similar to step S5, a shielding object that obstructs the reception of radio waves from positioning satellites is identified around UAV1 (step S25), and the process proceeds to step S26.

[0054] In step S26, the control unit 16 acquires from the flight management server 2 satellite information indicating the predicted number of positioning satellites that can be captured at each waypoint planned to be passed through in the flight route, or the predicted DOP at each waypoint. Here, the satellite information may be acquired (stored in the storage unit 15) from the flight management server 2 before the start of the process shown in FIG. 12, or may be acquired by requesting the flight management server 2 in step S26. Note that the control unit 16 may acquire the above-described orbit information (for example, the satellite position at the passing time of each waypoint) from the flight management server 2 or the satellite orbit management server. In this case, the control unit 16 calculates the predicted number of positioning satellites or the predicted DOP based on the position of each waypoint and the acquired orbit information, etc.

[0055] Next, based on the satellite information acquired in step S26, the control unit 16 specifies a waypoint at which the predicted number of positioning satellites becomes equal to or greater than the first threshold value, or a waypoint at which the predicted DOP becomes equal to or less than the second threshold value, as a waypoint at which it is expected that the degradation of the positioning accuracy will recover (step S27). Note that before the processing of step S27, a fourth threshold value greater than the first threshold value or a fifth threshold value less than the second threshold value may be set. In this case, in step S27, based on the acquired satellite information, a waypoint at which the predicted number of positioning satellites becomes equal to or greater than the fourth threshold value, or a waypoint at which the predicted DOP becomes equal to or less than the fifth threshold value, is specified as a waypoint at which it is expected that the degradation of the positioning accuracy will recover.

[0056] Next, the control unit 16 executes flight control of the UAV1 toward the waypoint specified in step S27 (step S28). Next, the control unit 16 determines whether or not the UAV1 has reached the waypoint specified in step S27 (step S29). If it is determined that the UAV1 has not reached the waypoint (step S29: NO), the process returns to step S28. On the other hand, if it is determined that the UAV1 has reached the waypoint (step S29: YES), the process proceeds to step S23.

[0057] As described above, according to the above embodiment, the UAV 1 continuously acquires, as information on the positioning satellite, a parameter value that is an index of positioning accuracy based on the radio wave information from the positioning satellite captured during flight. When the acquired parameter value corresponds to a situation indicating a decrease in positioning accuracy, a shielding object that obstructs the reception of radio waves is identified around the UAV 1, and the UAV 1 is configured to move away from the identified shielding object. Therefore, even in a place with many shielding objects, the flight control of the UAV 1 can be safely performed. That is, it is possible to prevent unexpected situations from occurring, such as the UAV 1 flying in an unexpected direction or stopping on the spot, or the delay in the delivery of goods, due to the inability to sufficiently capture the positioning satellite. In particular, according to the above embodiment, even when it is not possible to sufficiently capture the positioning satellite in an urban area where buildings (high-rise buildings) are densely packed, it is possible to more effectively prevent unexpected situations from occurring or delays in the delivery of goods.

[0058] Note that the above embodiment is one embodiment of the present invention, and the present invention is not limited to the above embodiment. Various configurations and the like may be changed from the above embodiment without departing from the gist of the present invention, and in that case, it is also included in the technical scope of the present invention. In the above embodiment, the number of captured positioning satellites and DOP are described as examples of parameter values. However, as another example, the radio wave intensity from the positioning satellite may be used. In this case, the shielding object identification unit 162 continuously compares the radio wave intensity continuously acquired by the satellite information acquisition unit 161 with a sixth threshold value (for example, 40 dB / Hz). When the radio wave intensity becomes less than the sixth threshold value, it is considered that the situation indicates a decrease in positioning accuracy, and a shielding object that obstructs the reception of the above radio waves is identified around the UAV 1.

[0059] Also, in the above-described embodiment, when the control unit 16 of the UAV 1 continuously acquires a parameter value that is an index of the positioning accuracy and the acquired parameter value corresponds to a situation indicating a decrease in the positioning accuracy, a shielding object that obstructs the reception of radio waves is identified around the UAV 1, and flight control is performed to move away from the identified shielding object. However, such processing (for example, the processing shown in FIGS. 11 and 12) may be performed by the control unit 23 of the flight management server 2. In this case, the control unit 23 continuously acquires from the UAV 1 information on radio waves from positioning satellites captured by the positioning unit 12 while the UAV 1 is in flight, and based on the radio wave information, continuously acquires a parameter value that is an index of the positioning accuracy as information on the positioning satellites. Then, when the acquired parameter value corresponds to a situation indicating a decrease in the positioning accuracy (for example, the number of captured satellites is less than the first threshold value or the DOP is greater than the second threshold value), the control unit 23 identifies a shielding object that obstructs the reception of radio waves around the flying UAV 1 and performs flight control of the flying UAV 1 to move away from the identified shielding object. In such flight control, the control unit 23 transmits a flight control command for controlling the traveling direction of the UAV 1 to the UAV 1.

[0060] <Appendix> [1] The flight control device according to the present disclosure includes an acquisition unit that continuously acquires, as information on the positioning satellites, a parameter value that is an index of the positioning accuracy based on information on radio waves from positioning satellites captured by a flying unmanned aerial vehicle; a specifying unit that specifies a shielding object that obstructs the reception of the radio waves around the flying unmanned aerial vehicle when the parameter value corresponds to a situation indicating a decrease in the positioning accuracy; and a flight control unit that performs flight control of the unmanned aerial vehicle to move away from the specified shielding object. Thereby, even in a place with many shielding objects, flight control of the unmanned aerial vehicle can be safely performed.

[0061] [2] In the flight control device according to [1] above, the specifying unit specifies the shielding object based on the height of the ground objects existing around the flying unmanned aerial vehicle. Thereby, the shielding object can be specified more appropriately.

[0062] [3] In the flight control device according to [2] above, the specifying unit specifies the height of the ground object from the map data around the unmanned aircraft during flight, and specifies the shielding object based on the height of the specified ground object. This enables more efficient specification of the shielding object.

[0063] [4] In the flight control device according to any one of [1] to [3] above, the acquisition unit continuously acquires the number of captured positioning satellites as the parameter value, and the specifying unit continuously compares the continuously acquired number of captures with a first threshold value. When the number of captures is less than the first threshold value, it is considered that the situation indicates a decrease in positioning accuracy, and a shielding object that obstructs the reception of the radio wave is specified around the unmanned aircraft. This enables more accurate specification of the shielding object.

[0064] [5] In the flight control device according to any one of [1] to [3] above, the acquisition unit continuously acquires the rate of decrease in positioning accuracy as the parameter value, and the specifying unit continuously compares the continuously acquired rate of decrease with a second threshold value. When the rate of decrease is greater than the second threshold value, it is considered that the situation indicates a decrease in positioning accuracy, and a shielding object that obstructs the reception of the radio wave is specified around the unmanned aircraft. This enables more accurate specification of the shielding object.

[0065] [6] In the flight control device according to any one of [1] to [5] above, when the value obtained by subtracting the altitude of the unmanned aircraft from the height of the shielding object is 0 or more and not more than a third threshold value, the flight control unit performs flight control of the unmanned aircraft so that the unmanned aircraft ascends in the vertical direction. This enables more rapid recovery from a decrease in positioning accuracy.

[0066] [7] In the flight control device according to any one of [1] to [5] above, when the value obtained by subtracting the altitude of the unmanned aircraft from the height of the shielding object is 0 or more and greater than a third threshold value, the flight control unit controls the flight of the unmanned aircraft so that the unmanned aircraft moves away horizontally from the shielding object while ascending. Thereby, it is possible to recover more quickly from the decrease in positioning accuracy.

[0067] [8] In the flight control device according to any one of [1] to [5] above, the flight control unit is characterized in that when the height of the shielding object is equal to or less than a third threshold value, the flight control unit controls the flight of the unmanned aircraft so that the unmanned aircraft ascends in the vertical direction. Thereby, it is possible to recover more quickly from the decrease in positioning accuracy.

[0068] [9] In the flight control device according to any one of [1] to [5] above, the flight control unit is characterized in that when the height of the shielding object is greater than a third threshold value, the flight control unit controls the flight of the unmanned aircraft so that the unmanned aircraft moves away horizontally from the shielding object while ascending. Thereby, it is possible to recover more quickly from the decrease in positioning accuracy.

[0069]

[10] In the flight control device according to [7] or [9] above, when the flight control unit determines that there is another shielding object in the direction away from the shielding object, the flight control unit calculates an ascending angle at which the unmanned aircraft does not collide with the other shielding object, and controls the flight of the unmanned aircraft to ascend at the calculated ascending angle. Thereby, it is possible to recover more safely from the decrease in positioning accuracy.

[0070]

[11] In the flight control device according to [7] or [9] above, when the flight control unit determines that there is another shielding object in the direction away from the shielding object, the flight control unit controls the flight of the unmanned aircraft to ascend through the central portion between the two shielding objects. Thereby, it is possible to recover more safely from the decrease in positioning accuracy.

[0071]

[12] In the flight control device described in [4] above, when the number of captures becomes equal to or greater than the first threshold value due to the unmanned aircraft ascending according to the flight control, the flight control unit controls the flight of the unmanned aircraft so that the unmanned aircraft gradually descends to a predetermined point. This enables the unmanned aircraft to return to the flight route before ascending more safely.

[0072]

[13] In the flight control device described in [5] above, when the rate of decrease becomes equal to or less than the second threshold value due to the unmanned aircraft ascending according to the flight control, the flight control unit controls the flight of the unmanned aircraft so that the unmanned aircraft gradually descends to a predetermined point. This enables the unmanned aircraft to return to the flight route before ascending more safely.

[0073]

[14] In the flight control device described in [1] above, the flight control unit identifies a waypoint among the waypoints scheduled to be passed through in the flight route of the unmanned aircraft at which a decrease in the positioning accuracy is expected to recover, and controls the flight of the unmanned aircraft toward the identified waypoint while avoiding the identified obstacle. This enables a quicker return to the original flight route and recovery from the decrease in positioning accuracy.

[0074]

[15] In the flight control device described in

[14] above, the flight control unit acquires the predicted number of positioning satellites that can be captured at a waypoint scheduled to be passed through in the flight route of the unmanned aircraft, and identifies the waypoint at which the acquired predicted number of captures becomes equal to or greater than the first threshold value as the waypoint at which a decrease in the positioning accuracy is expected to recover. This enables the waypoint at which a decrease in the positioning accuracy is expected to recover to be identified more accurately.

[0075]

[16] In the flight control device described in

[15] above, the flight control unit sets a fourth threshold value greater than the first threshold value, and identifies, as a waypoint at which the reduction in positioning accuracy is expected to recover, a waypoint at which the predicted number of positioning satellites that can be captured at the waypoint through which passage is scheduled is equal to or greater than the fourth threshold value. Thereby, even if the point corresponding to the situation indicating the reduction in positioning accuracy is immediately before the next waypoint to be headed, it is possible to recover more safely from the reduction in positioning accuracy.

[0076]

[17] In the flight control device described in

[14] above, the flight control unit acquires the predicted reduction rate of the positioning accuracy at the waypoint through which passage is scheduled in the flight route of the unmanned aircraft, and identifies, as a waypoint at which the reduction in positioning accuracy is expected to recover, a waypoint at which the acquired predicted reduction rate is equal to or less than a second threshold value. Thereby, it is possible to more accurately identify a waypoint at which the reduction in positioning accuracy is expected to recover.

[0077]

[18] In the flight control device described in

[17] above, the flight control unit sets a fifth threshold value smaller than the second threshold value, and identifies, as a waypoint at which the reduction in positioning accuracy is expected to recover, a waypoint at which the predicted reduction rate of the positioning accuracy at the waypoint through which passage is scheduled is equal to or less than the fifth threshold value. Thereby, even if the point corresponding to the situation indicating the reduction in positioning accuracy is immediately before the next waypoint to be headed, it is possible to recover more safely from the reduction in positioning accuracy.

[0078]

[19] The flight control method according to the present disclosure is a flight control method executed by a computer, including: continuously acquiring, as information regarding the positioning satellite, a parameter value serving as an index of positioning accuracy based on information on radio waves from the positioning satellite captured by an unmanned aircraft during flight; identifying a shielding object that obstructs reception of the radio waves around the unmanned aircraft during flight when the parameter value corresponds to a situation indicating a decrease in the positioning accuracy; and performing flight control of the unmanned aircraft so as to move away from the identified shielding object.

[0079]

[20] The unmanned aircraft according to the present disclosure is an unmanned aircraft capable of autonomous flight, including: an acquisition unit that continuously acquires, as information regarding the positioning satellite, a parameter value serving as an index of positioning accuracy based on information on radio waves from the positioning satellite captured during flight; an identification unit that identifies a shielding object that obstructs reception of the radio waves around the unmanned aircraft during flight when the parameter value corresponds to a situation indicating a decrease in the positioning accuracy; and a flight control unit that performs flight control so that the unmanned aircraft moves away from the identified shielding object.

Explanation of Signs

[0080] 1 UAV 2 Flight management server 11 Driving unit 12 Positioning unit 13 Communication unit 14 Sensor unit 15 Storage unit 16 Control unit 161 Satellite information acquisition unit 162 Shielding object identification unit 163 Flight control unit 21 Communication unit 22 Storage unit 23 Control unit S Flight control system NW Communication network

Claims

1. An acquisition unit that continuously acquires, as information on the positioning satellite, a parameter value that is an index of positioning accuracy based on information on radio waves from the positioning satellite captured by an unmanned aircraft during flight; A specifying unit that specifies an obstacle that obstructs reception of the radio wave in the vicinity of the unmanned aircraft during flight when the parameter value corresponds to a situation indicating a decrease in the positioning accuracy; A flight control unit that performs flight control of the unmanned aircraft so as to move away from the specified obstacle; A flight control device comprising the above.

2. The flight control device according to claim 1, wherein the specifying unit specifies the obstacle based on the height of ground features existing in the vicinity of the unmanned aircraft during flight.

3. The flight control device according to claim 2, wherein the specifying unit specifies the height of the ground feature from map data in the vicinity of the unmanned aircraft during flight, and specifies the obstacle based on the specified height of the ground feature.

4. The acquisition unit continuously acquires the number of captures of the positioning satellite as the parameter value, The specifying unit continuously compares the continuously acquired number of captures with a first threshold value, and when the number of captures is less than the first threshold value, determines that it corresponds to a situation indicating a decrease in the positioning accuracy, and specifies an obstacle that obstructs reception of the radio wave in the vicinity of the unmanned aircraft. The flight control device according to claim 1.

5. The acquisition unit continuously acquires the rate of decrease in the positioning accuracy as the parameter value, The specifying unit continuously compares the continuously acquired rate of decrease with a second threshold value, and when the rate of decrease is greater than the second threshold value, determines that it corresponds to a situation indicating a decrease in the positioning accuracy, and specifies an obstacle that obstructs reception of the radio wave in the vicinity of the unmanned aircraft. The flight control device according to claim 1.

6. The flight control unit according to any one of claims 1 to 5, wherein when the value obtained by subtracting the altitude of the unmanned aircraft from the height of the obstacle is 0 or more and not more than a third threshold value, the flight control unit performs flight control of the unmanned aircraft so that the unmanned aircraft ascends in the vertical direction.

7. When the value obtained by subtracting the altitude of the unmanned aircraft from the height of the shield is 0 or more and greater than a third threshold value, the flight control unit performs flight control of the unmanned aircraft so that the unmanned aircraft moves away horizontally from the shield while ascending. The flight control device according to claim 1, characterized in that.

8. When the height of the shield is less than or equal to a third threshold value, the flight control unit performs flight control of the unmanned aircraft so that the unmanned aircraft ascends in the vertical direction. The flight control device according to any one of claims 1 to 5, characterized in that.

9. When the height of the shield is greater than a third threshold value, the flight control unit performs flight control of the unmanned aircraft so that the unmanned aircraft moves away horizontally from the shield while ascending. The flight control device according to claim 1, characterized in that.

10. When it is determined that there is another shield in the direction away from the shield, the flight control unit calculates an ascending angle at which the unmanned aircraft does not collide with the other shield, and ascends at the calculated ascending angle. The flight control device according to claim 7 or 9, characterized in that flight control of the unmanned aircraft is performed.

11. When it is determined that there is another shield in the direction away from the shield, the flight control unit performs flight control of the unmanned aircraft so that it ascends through the central portion between the two shields. The flight control device according to claim 7 or 9, characterized in that.

12. When the capture number becomes equal to or greater than the first threshold value due to the ascent of the unmanned aircraft according to the flight control, the flight control unit controls the flight of the unmanned aircraft so that the unmanned aircraft gradually descends to a predetermined point. The flight control device according to claim 4, characterized in that.

13. When the decrease rate becomes less than or equal to the second threshold value due to the ascent of the unmanned aircraft according to the flight control, the flight control unit controls the flight of the unmanned aircraft so that the unmanned aircraft gradually descends to a predetermined point. The flight control device according to claim 5, characterized in that.

14. Among the waypoints scheduled to be passed in the flight route of the unmanned aircraft, the flight control unit identifies a waypoint at which it is expected that the decrease in the positioning accuracy will recover, and while avoiding the identified shield, The flight control device according to claim 1, characterized in that flight control of the unmanned aircraft is performed toward the identified waypoint.

15. The flight control unit acquires the predicted number of positioning satellites that can be captured at a waypoint scheduled to be passed through in the flight route of the unmanned aircraft, and identifies a waypoint at which the acquired predicted number of captured satellites is equal to or greater than a first threshold value as a waypoint at which it is expected that the degradation of the positioning accuracy will recover. The flight control device according to claim 14, characterized in that.

16. The flight control unit sets a fourth threshold value greater than the first threshold value, and identifies a waypoint at which the predicted number of positioning satellites that can be captured at the waypoint scheduled to be passed through is equal to or greater than the fourth threshold value as a waypoint at which it is expected that the degradation of the positioning accuracy will recover. The flight control device according to claim 15, characterized in that.

17. The flight control unit acquires the predicted degradation rate of the positioning accuracy at a waypoint scheduled to be passed through in the flight route of the unmanned aircraft, and identifies a waypoint at which the acquired predicted degradation rate is equal to or less than a second threshold value as a waypoint at which it is expected that the degradation of the positioning accuracy will recover. The flight control device according to claim 14, characterized in that.

18. The flight control unit sets a fifth threshold value smaller than the second threshold value, and identifies a waypoint at which the predicted degradation rate of the positioning accuracy at the waypoint scheduled to be passed through is equal to or less than the fifth threshold value as a waypoint at which it is expected that the degradation of the positioning accuracy will recover. The flight control device according to claim 17, characterized in that.

19. A flight control method executed by a computer, comprising: continuously acquiring a parameter value that is an index of positioning accuracy as information on the positioning satellite based on information on radio waves from positioning satellites captured by an unmanned aircraft during flight; identifying a shielding object that obstructs reception of the radio wave in the vicinity of the unmanned aircraft during flight when the parameter value corresponds to a situation indicating degradation of the positioning accuracy; performing flight control of the unmanned aircraft so as to move away from the identified shielding object; A flight control method characterized by including.

20. An unmanned aircraft capable of autonomous flight, comprising: an acquisition unit that continuously acquires a parameter value that is an index of positioning accuracy as information on the positioning satellite based on information on radio waves from positioning satellites captured during flight; When the parameter value corresponds to a situation indicating a decrease in the positioning accuracy, a specifying unit that specifies a shielding object that obstructs the reception of the radio wave around the unmanned aircraft during flight; A flight control unit that performs flight control so that the unmanned aircraft moves away from the specified shielding object; An unmanned aircraft characterized by comprising the above.

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