JP2018095049A - Communication system including plural unmanned aircrafts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit deterioration in communication quality in a system for relaying communication using a plurality of unmanned aircrafts.SOLUTION: A communication system 1 is constituted of three unmanned aircraft 5 (5A, 5B, 5C) including a leader machine 5A flying a foremost position and two relay machines 5B, 5C for relaying communication between a wireless station 50 and the leader machine 5A. The relay machines 5B, 5C control own machine to fly so as to close to the preceding unmanned aircraft when a measurement value relating to wireless communication quality becomes less than a prescribed threshold.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a communication system having a plurality of unmanned aerial vehicles.

  Conventionally, a system for relaying communication using a plurality of unmanned aircraft has been proposed. For example, Patent Document 1 below discloses an information collection system in which information collected by an information collection vehicle is transmitted to a ground station via a relay vehicle. Patent Document 2 below discloses a system in which a control message from a control device is relayed from a first unmanned aircraft to a second unmanned aircraft. Such a system enables communication in places where radio waves do not reach.

JP2013-107496A JP 2013-128287 A

  However, the conventional system as described above may cause various problems due to the environmental change not being fully considered. For example, the radio wave condition is considered to change depending on the geographical conditions of the area where the unmanned aircraft flies, the weather at the time of flight, and the like, but the conventional system does not consider such a change in the radio wave condition. As a result, sufficient communication quality may not be realized.

  An embodiment of the present invention has an object of suppressing deterioration in communication quality in a system that relays communication using a plurality of unmanned aircraft. Other objects of the embodiments of the present invention will become apparent by referring to the entire specification.

  A communication system according to an embodiment of the present invention includes a leader aircraft that flies at the head and a preceding unmanned aircraft that flies and relays communication between a first radio station and the leader aircraft 1 or A communication system having a plurality of unmanned aerial vehicles including a plurality of repeaters, wherein the repeater performs wireless communication, and a communication quality measurement unit that obtains measurement values related to the quality of wireless communication in the communication unit And a control unit that controls the flight of the aircraft, and when the measurement value obtained by the communication quality measurement unit is less than a predetermined threshold, Control the flight of your aircraft so that Such a configuration suppresses deterioration in communication quality because the distance between unmanned aircraft approaches when the quality of wireless communication deteriorates.

  Here, the measurement value obtained by the communication quality measurement unit may include, but is not limited to, the received signal strength, the SN ratio, and the error rate.

  In the communication system described above, the control unit of the repeater controls the flight of the own aircraft so as to follow a predetermined relative position relative to the preceding unmanned aircraft, and the measured value is a predetermined value. When it becomes less than a threshold value, it may be configured to adjust the predetermined relative position so that the distance to the preceding unmanned aircraft approaches.

  Further, in the communication system described above, the control unit of the repeater is configured such that the distance from the preceding unmanned aerial vehicle is equal to or less than a predetermined standard distance while the measured value is equal to or greater than the predetermined threshold. Control the flight of the aircraft, and if the measured value is less than the predetermined threshold, the distance from the preceding unmanned aircraft is less than a predetermined safety distance smaller than the predetermined standard distance. It can be configured to control the flight of the aircraft.

  Further, in the communication system described above, the control unit of the last relay located closest to the first wireless station is such that the distance between the last repeater and the first wireless station is A predetermined command may be transmitted to the reader device when a predetermined safety distance is exceeded. Such a configuration can inform the reader that the distance to the first radio station is large.

  The communication system described above includes a second wireless station and one unmanned aerial vehicle in addition to the one or more repeaters relaying communication between the first wireless station and the leader aircraft. Communication with the other unmanned aerial vehicles other than the one unmanned aerial vehicle may be configured to be relayed. Such a configuration can increase communication redundancy by establishing two different communication paths of radio stations.

  In addition, the communication system described above may be configured such that the first wireless station and the plurality of unmanned aircraft form a communication network having a line type, mesh type, or tree type network topology.

  Various embodiments of the present invention suppress degradation of communication quality in a system that relays communication using a plurality of unmanned aircraft.

1 is a diagram schematically showing a configuration of a communication system 1 according to an embodiment of the present invention. The external view of the unmanned aerial vehicle 5. FIG. 3 is a block diagram schematically showing the configuration of the unmanned aerial vehicle 5. The figure for demonstrating the operation example of the communication system. The figure for demonstrating the operation example of the communication system. The figure for demonstrating the operation example of the communication system. The flowchart which illustrates the process repeatedly performed by the control part 20 of the relay machines 5B and 5C. The figure for demonstrating the operation example of the communication system. The figure for demonstrating the operation example of the communication system. The figure for demonstrating the operation example of the communication system. The figure which illustrates the communication system 1 which forms a mesh type network.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically showing a configuration of a communication system 1 according to an embodiment of the present invention. The communication system 1 is composed of three unmanned aerial vehicles 5 (5A, 5B, and 5C). Specifically, the communication between the leader machine 5A that flies at the head, the radio station 50, and the leader machine 5A is performed. It is comprised by two relay machine 5B, 5C to relay. In the embodiment of the present invention, the number of repeaters is not limited to two, and may be one, or three or more repeaters. The radio station 50 includes a dedicated remote control device (propo), a general-purpose device such as a smartphone and a tablet terminal, a communication satellite, or a mobile phone base station.

  FIG. 2 is an external view of the unmanned aerial vehicle 5, and FIG. 3 is a block diagram schematically showing the configuration of the unmanned aircraft 5. As shown in FIG. 2, the unmanned aerial vehicle 5 includes a main body 10 that is a box-shaped member having a hexagonal shape when viewed from above, six arms 11 that extend linearly outward from the main body 10, and each arm. 11, six motors 12 provided one by one at the outer end of the motor 11, six rotors 13 provided one by one above each motor 12 and driven by the motor 12, and provided below the main body 10. Leg 14. The six rotors 13 are arranged at substantially equal intervals on a virtual circle centering on the main body 10. The unmanned aerial vehicle 5 is configured as a multicopter that flies (climbs, descends, moves horizontally, changes directions, and the like) by lift and thrust generated by the rotation of the rotor 13.

  As shown in FIG. 3, the unmanned aerial vehicle 5 stores a control unit 20, a communication unit 21, a communication quality measurement unit 22, various sensors 25, a position detection unit 26, a photographing unit 27, and information. And a power source 30 that supplies power to each part of the unmanned aerial vehicle 5. At least some of these parts can be accommodated inside the box-shaped main body 10.

  The control unit 20 is configured as a small computer, for example, and controls each unit of the unmanned aircraft 5 including the motor 12.

  The communication unit 21 performs wireless communication between the wireless station 50 and the other unmanned aircraft 5. For example, the communication unit 21 is configured to include at least one of an RC receiver, a Wi-Fi module, a Bluetooth (registered trademark) module, a satellite communication module, or an LTE module.

  The communication quality measurement unit 22 obtains a measurement value related to the quality of wireless communication in the communication unit 21. In the present embodiment, the communication quality measuring unit 22 is configured to measure the received signal strength (RSSI value) in the communication unit 21. In the embodiment of the present invention, the measurement value related to the quality of wireless communication is not limited to the received signal strength, and includes, for example, the SN ratio or the error rate.

  The various sensors 25 include various sensors necessary for various controls of the unmanned aircraft 5. For example, the various sensors 25 include an altitude sensor (atmospheric pressure sensor), a direction sensor (electronic compass), an acceleration sensor, a gyro sensor (angular velocity sensor), and the like.

  The position detection unit 26 detects the current position of the unmanned aircraft 5. For example, the position detection unit 25 includes a GPS receiver.

  The photographing unit 27 is configured as a general digital camera capable of photographing still images and moving images. An image photographed through the photographing unit 27 can be recorded in the storage unit 28.

  The unmanned aerial vehicle 5 configured in this manner flies by remote control using a remote control device or the like by a user, automatic operation based on a preset flight plan, or autonomous control. Specifically, when the control unit 20 controls the motor 12 based on a flight command based on remote control, automatic piloting or autonomous control, and various values input from the various sensors 24, the motor 12 is rotationally driven. The unmanned aerial vehicle 5 ascends, descends, horizontally moves, and changes direction due to lift and thrust acting on the rotor 13. The six rotors 13 are configured such that the rotation directions of the two adjacent rotors 13 are opposite to each other, and the rotation directions of the two rotors 13 that are opposed via the main body 10 are the same direction. ing.

  For example, the unmanned aerial vehicle 5 hovers by balancing the gravity acting on the unmanned aircraft 5 itself and the upward force including the lift acting on the rotating rotor 13, and increases the number of rotations of the six rotors 13. It rises by increasing the upward force rather than the gravity, and descends by decreasing the rotational speed of the rotor 13 to make the upward force smaller than the gravity.

  Further, for example, the unmanned aerial vehicle 5 is inclined in a specific direction by changing the rotational speed of at least a part of the six rotors 13, and the rotation surface of the rotor 13 is inclined with respect to the horizontal along with the inclination. Due to the thrust component in the horizontal direction generated by For example, the unmanned aerial vehicle 5 makes the rotational speeds of the two rotors 13 located on the specific direction side among the six rotors 13 smaller than the rotational speeds of the two rotors 13 located on the opposite side of the specific direction. Thus, it is possible to move horizontally in the specific direction.

  Further, for example, the unmanned aerial vehicle 5 has the rotational speed of the three rotors 13 rotating in a specific direction among the six rotors 13 smaller than the rotational speed of the three rotors 13 rotating in the direction opposite to the specific direction. By doing so, the direction is changed (horizontal rotation) in the specific direction.

  Next, the operation of the communication system 1 of the present embodiment will be described. As described above, the communication system 1 includes the leader device 5A and the two relay devices 5B and 5C that relay communication between the leader device 5A and the radio station 50. The relay machine 5B is controlled to fly following the leader machine 5A, and the relay machine 5C is controlled to fly following the relay machine 5B. That is, the repeater in the communication system 1 is controlled to fly following the preceding one unmanned aircraft. The communication protocol used in the communication system 1 is not particularly limited, and examples thereof include Wi-Fi, Bluetooth (registered trademark), satellite communication, LTE, and the like.

  Flight following a leading unmanned aerial vehicle can be realized by applying a known leader-follower control. For example, the repeaters 5B and 5C are controlled to follow a target relative position, which is a relative position with respect to the preceding unmanned aircraft 5 (leader 5A or repeater 5B). The target relative position is set, for example, as a position separated by Rp in the backward direction and Lp in the lateral direction with respect to the traveling direction of the preceding unmanned aircraft 5. Such a control method is described, for example, in a paper written by Daisuke Nakazawa, Satoshi Suzuki, Satoru Sakai, and Kenzo Nonami, “Self-controlled flight control of a small unmanned helicopter”, Japan Society of Mechanical Engineers (C), 74, 747, 2008. In November. Note that the flight following the preceding unmanned aerial vehicle can also be performed using a technique for analyzing an image including the preceding unmanned aerial vehicle photographed via the photographing unit 27.

  Here, a case will be described in which the communication system 1 is applied to relay of communication between the leader aircraft 5A that surveys and flies in a predetermined area on the sea where radio waves from the ground do not reach and the ground radio station 50. In FIG. 4, an area aa on the sea is an investigation target area, and the leader machine 5A first starts flying toward the area aa. The leader machine 5A flies, for example, by automatic piloting according to a preset flight plan. Specifically, the flight of the leader 5A is controlled based on the flight route included in the flight plan, the current position of the own aircraft detected by the position detector 26, and the like. At this stage, communication between the reader 5A and the radio station 50 is performed directly.

  Next, the relay machine 5B starts flying. The relay machine 5B is controlled to follow the target relative position with respect to the preceding leader machine 5A. Specifically, the flight of the repeater 5B is controlled based on the target relative position, the current position of the own aircraft detected by the position detection unit 26, and the like. The target relative position is set such that the distance Dab (see FIG. 5) between the leader machine 5A and the relay machine 5B is equal to or less than the standard distance As. The standard distance Ast is set in advance as a distance that allows reliable communication between the unmanned aircraft 5 in a normal state. At this stage, communication between the reader device 5A and the radio station 50 is performed via relay by the relay device 5B.

  Subsequently, the relay machine 5C starts flying. The relay machine 5C is controlled to follow the target relative position with respect to the preceding relay machine 5B. The target relative position is set such that the distance Dbc (see FIG. 6) between the relay machine 5B and the relay machine 5C is equal to or less than the standard distance As. At this stage, the leader machine 5A reaches the area aa which is the target area of the survey flight, and communication between the leader machine 5A and the radio station 50 is performed via relaying by the relay machines 5B and 5C. In this way, a plurality of unmanned aircraft 5 provided in the communication system 1 is arranged, and communication between the reader 5A and the radio station 50 is established. It is also possible to transmit any command including a flight command from the leader device 5A to the relay devices 5B and 5C.

  FIG. 7 is a flowchart illustrating processing repeatedly executed by the control unit 20 of the relay devices 5B and 5C in the present embodiment. This process can also be executed in a period before the leader aircraft 5A reaches the target region for the survey flight. As shown in the figure, the control unit 20 of the repeaters 5B and 5C acquires the measurement value (received signal strength) in the communication quality measurement unit 22, and compares the acquired measurement value with the threshold value T1. Is repeatedly executed while the value is equal to or greater than the threshold value T1 (steps S100 and S110). That is, the control unit 20 of the relay devices 5B and 5C monitors whether the received signal strength in the communication unit 21 is less than the threshold value T1.

  When the measured value in communication unit 21 is less than threshold value T1 (YES in step S110), control unit 20 of relays 5B and 5C adjusts the target relative position so as to approach the preceding unmanned aircraft 5 (step) S120). Specifically, the control unit 20 adjusts the target relative position so that the distance from the preceding unmanned aircraft 5 is equal to or less than the safety distance Asf that is smaller than the standard distance As described above. The safety distance Asf is set in advance as a distance at which communication between the unmanned aircraft 5 can be performed with a certain quality even when the radio wave condition is poor.

  FIG. 8 shows a state in which both the repeaters 5B and 5C are approaching the preceding unmanned aircraft 5 in accordance with the deterioration of the radio wave condition. Both the distance Dab 'between the leader machine 5A and the relay machine 5B and the distance Dbc' between the relay machine 5B and the relay machine 5C are less than or equal to the safe distance Asf. As described above, in the communication system 1 according to the present embodiment, when the radio wave condition is bad, the repeaters 5B and 5C are preceded by the unmanned aircraft so that the distance from the preceding unmanned aircraft 5 is equal to or less than the safe distance Asf. Since the aircraft 5 is approached, deterioration of communication quality is suppressed.

  Here, the number of repeaters 5B and 5C is planned in advance based on the distance from the radio station 50 to the area aa and the safety distance Asf. For example, if the distance from the radio station 50 to the area aa is L, by preparing as many relays as [L / Asf] ([] is a Gaussian symbol), even if the radio wave condition is bad, it is constant. Quality communication is realized. In addition, when a leader machine arrives at a target area without reducing the distance between airframes with good radio wave conditions, some repeaters may not be used.

  In addition, when the radio wave condition is poor and the distance between the unmanned aircraft 5 or the safe distance Asf or less, the distance between the last relay 5C and the radio station 50 exceeds the safe distance Asf. A predetermined command may be transmitted from the last relay machine 5C to the reader machine 5A. The reader 5A that has received the predetermined command controls, for example, the flight of its own so that the distance from the radio station 50 does not increase any more.

  The communication system 1 in the present embodiment can also be configured to simultaneously realize communication with the first wireless station and communication with the second wireless station. FIG. 9 illustrates the communication system 1 that simultaneously realizes communication with the first radio station 50A located on the land and communication with the second radio station 50B located on the remote island. The arrangement of the unmanned aerial vehicle 5 illustrated in FIG. 9 is the same as that in the case where the leader machine 5A flies in the above-described sea area aa described with reference to FIGS. 4-6, the leader machine 5A, the relay machine 5B, and the relay machine 5C. This is realized by starting the flight in the following order. In the communication system 1 in FIG. 9, communication between the reader 5A and the first radio station 50A is relayed by the relays 5B and 5C, and communication between the relay 5C and the second radio station 50B is performed. It is relayed by the relay machine 5B and the reader machine 5A. Thus, by establishing two different communication paths for wireless stations, communication redundancy in the communication system 1 can be increased. Note that the communication system 1 in FIG. 9 can also be controlled from the state illustrated in FIG. 9 to land on the remote island where the radio station 50B is located in the order of the leader machine 5A, the relay machine 5B, and the relay machine 5C. . In this case, the communication system 1 executes communication with the radio station 50A on the land side during the period until the unmanned aircraft 5 takes off from the land and reaches the state shown in FIG. During the period until landing, communication with the radio station 50B on the remote island side can be performed. In the example described above, the first and second radio stations are located on the land side to take off and the remote island side to land, but the present invention is not limited to this. For example, as illustrated in FIG. 10, when the unmanned aircraft 5 crosses a bay or a cove, the first radio station 50A is located where the takeoff takes place, while the second radio station 50B is in the middle of the flight path. It is arranged on land close to (for example, an intermediate point). In the state of FIG. 10, the communication between the leader machine 5A and the radio station 50A is relayed by the relay machines 5B and 5C, and the communication between the leader machine 5A and the radio station 50B is relayed by the relay machines 5B and 5D. Is done. Thereafter, when the leader machine 5A lands, for example, communication between the relay machine 5C and the radio station 50B is relayed by the relay machines 5B and 5D.

  In the communication system 1 of the present embodiment described above, the distance between the repeater that relays communication and the preceding unmanned aerial vehicle approaches when the measured value related to the quality of wireless communication becomes less than a predetermined threshold. In addition, since the flight of the own aircraft is controlled, deterioration of communication quality can be suppressed.

  The communication system 1 in the above-described embodiment is configured such that the radio station 50 and the plurality of unmanned aircraft 5 form a communication network having a line type (linear) network topology, but the communication in the other embodiment of the present invention. The system can be configured to form a communication network having a network topology other than the line type. For example, the system can be configured to form a communication network having a network topology such as a mesh type or a tree type. it can. For example, as shown in FIG. 11, by forming a communication network having a mesh type network topology, a plurality of communication paths between the radio station 50 and the reader 5A are secured, thereby realizing more reliable communication. Can do.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the shape, number, arrangement, or the like of each member in the above-described embodiment is appropriately changed. For example, the number of rotors included in the unmanned aerial vehicle in the embodiment of the present invention is not limited to six, and may be five or less or seven or more.

DESCRIPTION OF SYMBOLS 1 Communication system 5 Unmanned aircraft 5A Leader machine 5B, 5C Relay machine 10 Main-body part 12 Motor 13 Rotor 20 Control part 21 Communication part 22 Communication quality measurement part 25 Various sensors 26 Position detection part 27 Shooting part 28 Storage part 30 Power supply 50 Wireless station

Claims (6)

A plurality of unmanned aerial vehicles including a leader aircraft that flies at the head and one or more repeaters that follow the preceding unmanned aerial vehicle and fly between the first radio station and the leader aircraft A communication system comprising:
The repeater includes a communication unit that performs wireless communication, a communication quality measurement unit that obtains a measurement value related to the quality of wireless communication in the communication unit, and a control unit that controls the flight of the own device,
When the measurement value obtained by the communication quality measurement unit is less than a predetermined threshold, the control unit controls the flight of the aircraft so that the distance between the preceding unmanned aircraft approaches.
Communications system.   When the control unit of the repeater controls the flight of its own aircraft so as to follow a predetermined relative position relative to the preceding unmanned aircraft, and the measured value is less than a predetermined threshold The communication system according to claim 1, wherein the predetermined relative position is adjusted so that a distance from a preceding unmanned aerial vehicle approaches.   The control unit of the repeater controls the flight of the own aircraft so that the distance from the preceding unmanned aircraft is not more than a predetermined standard distance while the measured value is not less than the predetermined threshold, The flight of the own aircraft is controlled so that a distance from a preceding unmanned aerial vehicle is less than or equal to a predetermined safety distance smaller than the predetermined standard distance when the measured value is less than the predetermined threshold. 1 or 2 communication systems.   When the control unit of the last relay station located closest to the first wireless station side has a distance between the last relay station and the first wireless station exceeding the predetermined safety distance 4. The communication system according to claim 3, wherein a predetermined command is transmitted to the reader device.   In addition to relaying communication between the first wireless station and the leader aircraft by the one or more repeaters, communication between the second wireless station and one unmanned aircraft The communication system according to any one of claims 1 to 4, wherein another unmanned aircraft other than one unmanned aircraft relays. The communication system according to claim 1, wherein the first wireless station and the plurality of unmanned aircraft form a communication network having a line-type, mesh-type, or tree-type network topology.

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