Satellite constellation, communication satellite and automatic collision avoidance method

Abstract

To avoid collision between satellites by detecting a collision risk.SOLUTION: A satellite constellation 101 comprises a plurality of communicating satellite groups 102 forming orbital planes different from each other. The own satellite communicates with those before and after and left and right of the own satellite to receive orbital data of each communication satellite 110. The own satellite detects a risk of collision at an intersection point of an own orbital surface and an opposite orbital plane between the own satellite and the opposite satellite by analyzing, the orbital data of the own satellite and the received orbital data, and selects one of the own satellite and the opposite satellite as an avoidance satellite when the own satellite detects the risk of collision. When the own satellite is selected as the avoidance satellite, the own satellite changes a speed to change timing for passing through the intersection point.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to satellite constellations. [Background technology]

[0002] With the emergence of mega-constellations and the increase in debris, there are concerns about the increased risk of collisions in space, and therefore a collision avoidance method is desired. In mega-constellations that use inclined circular orbits, all intersections at the same altitude on the orbital planes that form a grid pattern in the mid-latitudes carry a risk of collision. Therefore, a mechanism is required to stagger the passing timing of all satellites during the design stage and to avoid collisions even if an unexpected shift in passing timing occurs.

[0003] Patent Document 1 discloses a satellite constellation forming system that avoids the risk of collision by forming a plurality of orbital planes with different orbital altitudes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 158505 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure aims to detect collision risks and to be able to avoid collisions between satellites. [Means for solving the problem]

[0006] The satellite constellation of the present disclosure forms a number of orbital planes in which the longitudinal components of the normal vectors differ from one another. the satellite constellation comprises a group of a plurality of communication satellites for forming the plurality of orbital planes; a self-contained satellite group, each of the plurality of communication satellite groups, is composed of a plurality of communication satellites flying in a self-contained orbital plane formed by the self-contained satellite group; Each of the plurality of communication satellites is a self-satellite, a communication system for receiving orbital data of each communication satellite of the satellite constellation by communicating with each of the communication satellites on the front, rear, left and right of the own satellite; an analysis device that detects a collision risk of the own satellite and a counterpart satellite flying in a counterpart orbital plane colliding at an intersection of the own orbital plane and the counterpart orbital plane by analyzing orbit data of the own satellite and the received orbital data, and selects either the own satellite or the counterpart satellite as an avoidance satellite when the collision risk is detected; and a propulsion device that changes the speed of the own satellite when the own satellite is selected as the avoidance satellite, thereby changing the timing at which the own satellite passes through the node. Effect of the Invention

[0007] According to the present disclosure, collision risks can be detected and collisions between satellites can be avoided. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram of a satellite constellation system 100 according to a first embodiment. [Diagram 2] FIG. 2 is a configuration diagram of a communication satellite 110 according to the first embodiment. [Diagram 3] FIG. 2 is a diagram showing a trajectory group 103 according to the first embodiment. [Figure 4] FIG. 2 is a diagram showing a track 104 according to the first embodiment. [Diagram 5] FIG. 2 is a diagram showing raceway surfaces (1) and (2) according to the first embodiment. [Figure 6] FIG. 2 is a diagram showing raceway surfaces (1) to (5) in the first embodiment. [Figure 7] FIG. 2 is a diagram showing overlapping raceway surfaces (1) to (5) according to the first embodiment. [Figure 8]FIG. 2 is a diagram showing inclined track surfaces (1) to (5) in the first embodiment. [Figure 9] FIG. 2 is a diagram showing inclined track surfaces (1) to (5) in the first embodiment. [Figure 10] FIG. 2 is a diagram showing raceway surfaces (2) to (5) superimposed on the raceway surface (1) in the first embodiment. [Figure 11] FIG. 2 is a diagram showing orbital planes (1) to (5) indicating the northernmost point in the first embodiment. [Figure 12] FIG. 2 is a diagram showing orbital planes (1) to (5) on which coincident points are marked in the first embodiment. [Figure 13] FIG. 2 is a diagram showing orbital planes (1) to (5) on which coincident points are marked in the first embodiment. [Figure 14] FIG. 2 is a diagram showing track surfaces (1) to (5) depicting ascent and descent in the first embodiment. [Figure 15] FIG. 2 is a diagram showing overlapping raceway surfaces (1) to (5) according to the first embodiment. [Figure 16] FIG. 2 is a diagram showing track surfaces (1) to (5) depicting ascent and descent in the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In the embodiments and drawings, the same or corresponding elements are denoted by the same reference numerals. The description of elements denoted by the same reference numerals as those of the elements described above will be omitted or simplified as appropriate.

[0010] Embodiment 1 The satellite constellation system 100 will be described with reference to FIGS.

[0011] ***Configuration Description*** The configuration of a satellite constellation system 100 will be described with reference to FIG. The satellite constellation system 100 includes a satellite constellation 101 that forms a plurality of orbital planes in which the longitudinal components of normal vectors differ from one another. The satellite constellation 101 comprises a number of communication satellites 102 forming a number of orbital planes. Communications satellite constellation 102 is made up of multiple communications satellites 110 . The communication satellite 110 is an artificial satellite having a communication function.

[0012] The satellite constellation system 100 includes a ground facility 120 . The ground equipment 120 includes a satellite control device 121 and a communication device 122 . The satellite control device 121 is a computer equipped with hardware such as a processing circuit and an input / output interface. The satellite control device 121 is connected to a communication device 122 via the input / output interface. The satellite control device 121 generates various commands for each communication satellite 110 in order to control the satellite constellation 101. The communication device 122 communicates with each communication satellite 110. Specifically, the communication device 122 transmits various commands to each communication satellite 110.

[0013] The configuration of the communications satellite 110 will be described with reference to FIG. The communications satellite 110 comprises a propulsion system 111 , an attitude control system 112 , a satellite control system 113 , a communications system 114 , an analysis system 118 , and a storage device 119 . The propulsion device 111 is a device that provides propulsive force to the communications satellite 110 and adjusts the speed of the communications satellite 110. Specifically, the propulsion device 111 is an electric propulsion device. For example, the propulsion device 111 is an ion engine or a Hall thruster. The attitude control device 112 is a device for controlling attitude elements such as the attitude of the communication satellite 110 and the angular velocity of the communication satellite 110. The attitude control device 112 changes each attitude element to a desired direction. Alternatively, the attitude control device 112 maintains each attitude element in a desired direction. The attitude control device 112 includes an attitude sensor, an actuator, and a controller. The attitude sensor is a gyroscope, an earth sensor, a sun sensor, a star tracker, a thruster, a magnetic sensor, etc. The actuator is an attitude control thruster, a momentum wheel, a reaction wheel, a control moment gyro, etc. The controller controls the actuator according to the measurement data of the attitude sensor or various commands from the ground equipment 120. The satellite controller 113 is a computer equipped with hardware such as a processing circuit and an input / output interface, and controls the communications satellite 110. For example, the satellite controller 113 controls the communications satellite 110 in accordance with various commands from the ground equipment 120. The communication system 114 includes a front / rear communication device 115 , a left / right communication device 116 , and a ground communication device 117 . The front and rear communication device 115 is a communication device for communicating with other communication satellites 110. The front and rear communication device 115 points forward of the communication satellite 110 to communicate with the forward communication satellite 110. The front and rear communication device 115 also points backward of the communication satellite 110 to communicate with the rear communication satellite 110. The left-right communication device 116 is a communication device for communicating with other communication satellites 110. The left-right communication device 116 points to the left of the communication satellite 110 to communicate with the left communication satellite 110. The left-right communication device 116 also points to the right of the communication satellite 110 to communicate with the right communication satellite 110. The ground communication device 117 is a communication device for communicating with the ground equipment 120 . The analysis device 118 is a computer equipped with hardware such as a processing circuit and an input / output interface, and analyzes the orbital data of each communication satellite 110 to detect a collision risk. The storage device 119 is a storage device that stores various data used in the processing of the communication satellites 110. For example, the storage device 119 stores orbital data of each communication satellite 110 and the like. The orbit data indicates an orbit along which the communications satellite 110 is scheduled to fly (future orbit) or an orbit along which the communications satellite 110 has actually flown (past orbit).

[0014] The processing circuits provided in each of the satellite control device 113, the analysis device 118, and the satellite control device 121 will be described. The processing circuitry may be dedicated hardware or may be a processor that executes a program stored in a memory. In the processing circuit, some functions may be realized by dedicated hardware and the remaining functions may be realized by software or firmware, i.e. the processing circuit may be realized by hardware, software, firmware or a combination thereof. The dedicated hardware may be, for example, a single circuit, multiple circuits, a programmed processor, parallel programmed processors, an ASIC, an FPGA, or a combination of these. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field Programmable Gate Array.

[0015] ***Explanation of Operation*** In the satellite constellation system 100, a method for avoiding collisions between satellites is called an automatic collision avoidance method.

[0016] The automatic collision avoidance method is described below. The satellite constellation 101 includes a group of n communication satellites 102, which form n orbital planes, where "n" is an integer equal to or greater than two. Each of the n communication satellite constellations 102 is made up of m communication satellites 110, where "m" is an integer equal to or greater than two. The (n×m) communication satellites 110 move northward above the equator, shifting their phase from one another by (360 / (n×m)) degrees.

[0017] The operation of each communications satellite 110 in an automatic collision avoidance method is described below. The main communications satellites 102 are referred to as the home constellation. The host communications satellite 110 is referred to as the own satellite. The orbital plane in which the own satellite flies is called the own orbital plane. The communications satellite 110 that is the counterpart of the own satellite is called the counterpart satellite. The orbital plane in which the partner satellite flies is called the partner orbital plane.

[0018] First, the communication system 114 transmits orbital data of its own satellite to each of the communication satellites 110 of the satellite constellation 101 by communicating with each of the communication satellites 110 on the front, rear, left and right sides. The communication system 114 also receives orbital data for each of the communication satellites 110 in the satellite constellation 101 by communicating with each of the communication satellites 110 on the front, rear, left, and right sides.

[0019] Next, the analysis device 118 detects the risk of collision between the own satellite and the other satellite at the intersection of the own orbital plane and the other orbital plane (collision risk) by analyzing the own satellite's orbital data and the received orbital data. When a collision risk is detected, the analysis device 118 selects either the own satellite or the other satellite as an avoidance satellite. The avoidance satellite is a communication satellite 110 that performs an action (avoidance action) to avoid a collision risk. Specifically, the analysis device 118 selects the avoidance satellite based on the flight direction of the own satellite at the intersection and the flight direction of the other satellite at the intersection. For example, the analysis device 118 selects the one of the own satellite and the other satellite that flies north from the intersection as the avoidance satellite.

[0020] When the own satellite is selected as the avoidance satellite, the propulsion device 111 changes the speed of the own satellite to change the timing (passage timing) at which the own satellite passes through the node. For example, the propulsion device 111 operates according to an instruction from the satellite control device 113 or the analysis device 118.

[0021] When the own satellite changes the pass timing, the analysis device 118 generates difference data of the own satellite. The difference data indicates the difference between the orbit data before the pass timing is changed (pre-update orbit data) and the orbit data after the pass timing is changed (update orbit data). In addition, the communication system 114 transmits the update orbit data or the difference data to each communication satellite 110 of the satellite constellation 101 by communicating with each of the communication satellites 110 on the front, rear, left and right sides. In this case, the analysis device 118 analyzes the pre-update orbit data and the post-update orbit data or the difference data and the orbit data of each communication satellite 110 to detect a new collision risk.

[0022] If another communication satellite 110 (e.g., a partner satellite) changes its pass timing, the communication system 114 receives updated orbit data or difference data of the other communication satellite 110 by communicating with each of the communication satellites 110 on the front, rear, left, and right sides. In this case, the analysis device 118 analyzes the orbital data of the own satellite, the orbital data of each communication satellite 110, and the updated orbital data or difference data of the other communication satellites 110 to detect a new collision risk.

[0023] A description will now be given of detection of a collision risk by analysis device 118. Specifically, analysis device 118 detects a collision risk by at least one of the following methods. The analysis device 118 detects, as a collision risk, the presence of a counterpart satellite that will pass within a range of the design tolerance from the node at the future time when the own satellite will pass the node. The analysis device 118 has artificial intelligence (AI). The AI ​​machine-learns the deviation of the intersection based on the past intersections of the own orbital plane and each partner orbital plane. Then, the analysis device 118 detects, by the AI ​​after machine learning, the presence of a partner satellite that passes within the deviation range from the intersection at the future time when the own satellite passes the intersection, as a collision risk. The analysis device 118 has an artificial intelligence. The artificial intelligence machine-learns the maximum deviation of the intersection based on the past intersections of the own orbital plane and each partner orbital plane. Then, the analysis device 118 detects, by the artificial intelligence after machine learning, the presence of a partner satellite that passes within the range of the maximum deviation from the intersection at a future time when the own satellite passes the intersection, as a collision risk.

[0024] ***Addition to the first embodiment*** An embodiment will be described with reference to FIGS. FIG. 3 shows the trajectory group 103. The orbit group 103 is a plurality of orbits in which a plurality of communication satellites 102 fly. The communication satellites 102 fly in orbits above the Earth 109. Collision danger areas are areas where there is a risk of collision, and the mid-latitude areas are collision danger areas. The shaded circles represent the intersections of the orbital planes.

[0025] The communications satellite constellation 102 is made up of m communications satellites 110 . The m communication satellites 110 fly in orbits in the same orbital plane, evenly spaced with a phase shift of (360 / m) degrees. The number of communication satellites 102 is n. That is, the number of orbital planes in the satellite constellation 101 is n. The orbit of each orbital plane is an inclined circular orbit. An inclined circular orbit is both an inclined orbit and a circular orbit. The n orbital planes are evenly spaced with a phase shift of (360 / n) degrees in the longitude direction.

[0026] The following description will be given by way of example of a case in which eight (m=8) communication satellites 110 fly in the same orbital plane, and five (n=5) inclined circular orbits are evenly spaced in the longitude direction.

[0027] 4 shows the orbit 104 as viewed from the normal direction to the orbital plane, and eight communication satellites 110 flying in equal phases around the orbit 104. Each black star represents a communication satellite 110. Each dashed line connects two communication satellites 110 that face each other. The latitude of the center of the orbit 104 is the same as the latitude of the equator. The eight communication satellites 110 are evenly spaced with a phase angle shift of 45 degrees each. This allows the eight communication satellites 110 to fly at the same altitude while maintaining the same phase. Therefore, there is no risk of satellites colliding with each other in the same orbital plane.

[0028] Figure 5 shows two orbital planes (1) and (2) with different normal vectors but the same orbital altitude. The black crosses represent the intersections of the two orbital planes (1) and (2). The dashed lines represent the intersections of the two orbital planes (1) and (2). The two orbital planes (1) and (2) have a risk of collision between the satellites at two points on their intersecting line (intersections). In other words, if the orbital altitudes of the two orbital planes are the same, a collision risk occurs at the intersection of the two orbital planes. One effective way to eliminate this collision risk is to stagger the timing at which the satellites pass through the two points on the line of intersection. When attention is paid to the timing of passing over the equator, if the communication satellites 110 in each orbital plane pass over the equator at different times, the risk of collision at each node is eliminated.

[0029] Figure 6 shows five orbital planes (1) to (5) as viewed from their respective normal directions. Five circles represent the five orbital planes (1) to (5). Four straight lines drawn in each orbital plane connect the flying positions of two communications satellites 110 facing each other. The latitude of the center of each orbital plane is the same as the latitude of the equator. The eight flight positions are evenly spaced on each of the orbital planes (1) to (5). Specifically, the phase of each flight position is shifted by 45 degrees. In the five orbital planes (1) to (5), the eight flight positions are shifted equally from each other with respect to the equatorial plane. Specifically, the phases of the eight flight positions for each orbital plane are shifted by 9 degrees. Figure 7 shows five orbital planes (1) to (5) superimposed with their normal vectors aligned.

[0030] In these orbital planes (1) to (5), the communication satellites 110 pass over the equator at different times, so satellites in different orbital planes do not collide with each other over the equator. In addition, when the number of communication satellites 110 in the same orbital plane is an even number, two communication satellites 110 facing each other in the same orbital plane will pass over the equator at the same time. However, since they fly at different positions above the equator, the two communication satellites 110 will not collide. In other words, the 40 communication satellites 110 in orbital planes (1) to (5) will not collide over the equator.

[0031] FIG. 8 shows orbital planes (1) to (5) as viewed from the north pole, with their normal vectors inclined by the same amount as the orbital inclination angles. Figure 9 shows the orbital planes (1) to (5) of Figure 8, with the longitudinal components of their normal vectors tilted at equal intervals. The orbital planes (1) to (5) rotate so that the longitudinal components of their normal vectors are shifted by 72 degrees from each other. In Figure 10, orbital planes (2) to (5) from Figure 9 are shown superimposed on orbital plane (1) from Figure 9. The two dashed lines in each orbital plane represent the major and minor axes. Orbital plane (1) has intersections with each of orbital planes (2) to (5). Figure 11 shows the orbital planes (1) to (5) in Figure 10, with their northernmost points marked. Each star indicates the northernmost point of the orbital plane. FIG. 12 shows the orbital planes (1) to (5) of FIG. 11, indicating the points of coincidence of orbital altitudes and the flight direction of the communications satellite 110. The black crosses represent the points of coincidence on the north pole side. The white crosses represent the points of coincidence on the south pole side. The points of coincidence correspond to the points where the orbital altitudes coincide on the intersection line between the orbital planes. The arrows represent the flight direction of the communications satellite 110. FIG. 13 shows the orbital planes (2) to (5) of FIG. 9, superimposed on the orbital plane (1) of FIG. 9, with the coincidence points of orbital altitudes indicated. Fig. 14 shows the orbital planes (1) to (5) of Fig. 12, which indicate the rise and fall of each communication satellite 110 at each coincidence point. [N / S] indicated at each coincidence point means that the communication satellite 110 in orbital plane (1) rises north from the South Pole, and the communication satellite 110 in the other orbital plane falls south from the North Pole. [S / N] indicated at each coincidence point means that the communication satellite 110 in orbital plane (1) falls south from the North Pole, and the communication satellite 110 in the other orbital plane falls north from the South Pole. At each intersection point, a communication satellite 110 moving north from the Antarctic and a communication satellite 110 moving south from the Arctic intersect.

[0032] FIG. 15 shows orbital planes (1) to (5) as viewed from above the equator, superimposed with the longitude directions of their normal vectors aligned. Even though the communication satellites 110 in the orbital planes (1) to (5) pass over the equator at different times, there is a risk of collision between a communication satellite 110 moving north and a communication satellite 110 moving south at each intersection in the mid-latitude zone other than the equator. This is because, at the same latitude, the communication satellite 110 in one orbital plane moves north and the communication satellite 110 in the other orbital plane moves south at the same timing.

[0033] FIG. 16 shows orbital planes (2) to (5) of FIG. 9, which are superimposed on the orbital plane (1) of FIG. 9 and indicate the coincidence points of orbital altitude, the flight direction of the communication satellite 110, and the ascent and descent of the communication satellite 110. Each intersection point between the orbital planes is known, so it is possible to set satellites in different orbital planes not to pass through each intersection point at the same time at the early design stage. In the orbital planes (1) to (5), there is no combination of communications satellites 110 that pass through the nodes at the same time, so no collisions occur during normal operation. Thus, it is necessary to confirm in advance at the design stage that there will be no collisions at all intersections under ideal operating conditions.

[0034] Furthermore, it is necessary to confirm that there are no collisions at all intersections even if there are changes, within the design tolerances, in the phase angle between satellites in the orbital plane, the separation angle of the longitude components between the normal vectors of different orbital planes, the orbital altitude of each orbital plane, the eccentricity of each orbital plane, or the orbital inclination of each orbital plane. If tolerances are taken into consideration during the design stage and it is confirmed that collisions will not occur, collisions will not occur in orbit during normal operation. However, there is a risk of collision during the development of the satellite constellation 101. Specifically, there is a risk of collision when a new communications satellite 110 is launched into orbit, when an end-of-life communications satellite 110 deorbits, and when a failed communications satellite 110 deviates from its designed orbit.

[0035] For a satellite constellation consisting of around 40 communications satellites, the risk of collision in the vastness of space is negligible. However, in recent years, there has been an increase in the number of plans to orbit several thousand communications satellites at the same orbital altitude. As the number of satellites increases, the risk of collision becomes non-negligible.

[0036] Furthermore, in the unlikely event that a collision were to occur at the same orbital altitude, and a large amount of debris were to break down and fly away, there would be a risk that the debris would begin to fly in nearby orbit and collide with other communications satellites at the same orbital altitude. A situation in which this chain reaction of collisions cannot be stopped is known as the Kessler Syndrome, and caution is required.

[0037] ***Features and Effects of the First Embodiment*** In the orbital plane of n, inclined circular orbits of the same orbital altitude are evenly spaced in the longitude direction. M communication satellites 110 fly in each orbital plane, shifted by equal phase angles. The communication satellite 110 includes a communication device (115) that communicates with the communication satellites 110 before and after it in the direction of travel in the same orbital plane. The m communication satellites 110 form a circular communication network in the same orbital plane. The communication satellite 110 is equipped with a communication device (116) that communicates with the communication satellites 110 in adjacent orbits on the left and right. The communication satellite group 102 in the n orbital planes forms a circular or spiral communication network in the longitude direction. The communication network in the same orbital plane and the communication network in the longitude direction form a mesh-like communication network. The communications satellite 110 includes an analysis device 118 . The analysis device 118 records in advance the north latitude θNxo and south latitude θSxo at which the orbital plane IDo on which the satellite itself flies intersects with the orbital plane IDx, the longitude component of the normal vector of which is different from that of the orbital plane IDo. “x” is an integer between 1 and n. The communication system 114 receives orbit information of a communication satellite IDxy flying on an orbital plane IDx via a mesh communication network, where "y" is an integer between 1 and m. The analysis device 118 analyzes the orbit information and derives that the satellite itself and a communication satellite IDxy flying in the orbital plane IDx will pass through the north latitude θNxo or the south latitude θSxo at the same time at the future time tz. Then, the communication satellite 110 moving north operates the propulsion device 111 to change the passing timing.

[0038] The conditions under which ships should take evasive action when a risk of collision between ships sailing at sea is predicted are predetermined. However, the conditions under which satellites should take evasive action when a collision risk between two satellites in space is predicted have not been specified. Therefore, if both satellites do not take evasive action, a collision will occur, and if both satellites take evasive action, the risk of collision will occur in a location different from the predicted location. In a communications satellite constellation, where multiple orbital planes intersect, there is a risk of a collision between a satellite traveling north from the South Pole to the North Pole and a satellite traveling south from the North Pole to the South Pole. If a collision is predicted, the satellite traveling north can take evasive action, which ensures that a collision can be avoided. If both satellites were to take evasive action independently, there would be a risk of collision at different locations. Therefore, similar to the rules for maritime navigation of ships, it is essential to determine in advance which satellite will take evasive action as a rule. Needless to say, the satellite heading south may take evasive action.

[0039] A mesh communication network is formed as follows. If each communication satellite flies north above the equator and communicates with a communication satellite in an adjacent orbit to the northeast at an azimuth angle equivalent to its orbital inclination, a circular communication network in the longitude direction above the equator is formed. Also, if each communication satellite communicates with a communication satellite in an adjacent orbit at an azimuth angle different from its orbital inclination, a spiral communication network is formed.

[0040] If collision analysis is performed unconditionally for all communication satellites that make up a communication satellite constellation, there will be an excessive number of variable parameters. This places a heavy burden on the analysis device. Furthermore, equipping each communication satellite with a high-speed analysis device will result in high costs. Furthermore, if the analysis time is long, collision avoidance will not be possible in time. Therefore, the latitudes at which there is a possibility of collision for each orbital plane are limited to only two points, north and south. This reduces the burden on the analysis device. It also enables quick analysis at low cost. It also allows for collision avoidance with ample time to be ensured.

[0041] The analysis device 118 analyzes the orbit information. At this time, the analysis device 118 derives that the own satellite and the communication satellite IDxy flying on the orbital plane IDx will pass through θNxo±ΔθNxo or θSxo±ΔθSxo at the same time at future time tz, including the width of the design tolerance (ΔθNxo, ΔθSxo) for the prerecorded north latitude θNxo and south latitude θSxo. Then, the communication satellite 110 moving north operates the propulsion device 111 to change the passing timing.

[0042] The analysis device 118 includes artificial intelligence (AI). The analysis device 118 performs machine learning of the deviation (δθNxo, δθSxo) from the intersection (θNxo, θSxo) of the orbital plane IDo and the orbital plane IDx based on the past orbit performance for the north latitude θNxo and the south latitude θSxo that have been recorded in advance. The analysis device 118 analyzes the orbit information and derives that there is a possibility that the own satellite and the communication satellite IDxy flying on the orbital plane IDx will pass through the range of θNxo±δθNxo or the range of θSxo±δθSxo at the same time at a future time tz. Then, the communication satellite 110 moving north operates the propulsion device 111 to change the passing timing.

[0043] The analysis device 118 includes artificial intelligence (AI). The analysis device 118 records in advance the north latitude θNxi and south latitude θSxi where the orbital plane IDi on which any communication satellite 110 flies intersects with the orbital plane IDx whose normal vector has a different longitudinal component from that of the orbital plane IDi. "i" is an integer between 1 and n. "x" is an integer between 1 and n. The analysis device 118 performs machine learning of the maximum deviation (δθNximax, δθSximax) for all combinations of satellites in all orbital planes based on the past orbital performance for the northern latitude θNxi and the southern latitude θSxi recorded in advance. The maximum deviation δθNximax is the maximum deviation of the intersection of the northern latitude θNxi in the flight performance during the normal operation phase from the intersection of the northern latitude θNxi assumed in the design phase. The maximum deviation δθSximax is the maximum deviation of the intersection of the southern latitude θSxi in the flight performance during the normal operation phase from the intersection of the southern latitude θSxi assumed in the design phase. The analysis device 118 analyzes the orbit information and derives that there is a possibility that the own satellite and the communication satellite IDxy flying on the orbital plane IDx will pass through the range of θNxo±δθNximax or the range of θSxo±δθSximax at the same time at future time tz. Then, the communication satellite 110 moving north operates the propulsion device 111 to change the passing timing.

[0044] When communication satellites take individual evasive action, the orbital altitude changes if the thrusters accelerate or decelerate. Also, if the thrusters are fired in the direction outside the orbital plane at the equinox, the orbital inclination changes. Therefore, the orbital information after collision avoidance may deviate from the tolerance range assumed in the design stage. And the relative phase angle between the orbital planes and the relative phase angle between the satellites changes, and the north latitude θNxi and south latitude θSxi that were not assumed in the design become intersections, which may cause another collision risk. For deviations that are not anticipated in the design, it is effective to use AI machine learning on orbit to determine the maximum value.

[0045] The communication satellite 110 that has taken evasive action notifies all communication satellites 110 of the orbit information after taking the evasive action (updated orbit information) via the mesh communication network.

[0046] As a result of updating the orbital information of a communications satellite that has taken evasive action, there is a possibility that the communications satellite may face a risk of collision with a communications satellite in an orbital plane that was not initially at risk of collision. However, by immediately notifying all communications satellites of the updated orbital information, the analysis devices of each communications satellite can confirm that there is no new risk of collision. In other words, the effect is that secondary disasters can be prevented.

[0047] The communications satellite 110 that has taken evasive action notifies all communications satellites 110 via the mesh communications network of the difference between the orbit information after the evasive action has been taken (updated orbit information) and the orbit information before the update. The analysis device 118 of each communication satellite 110 uses AI to machine-learn the difference information of orbit information associated with avoidance actions received in the past, and generates the maximum deviation (ΔθNavdmax, ΔθSavdmax). The analysis device 118 of each communication satellite 110 derives that there is a possibility that the own satellite and a communication satellite IDxy flying on the orbital plane IDx will pass through the range of θN±δθNavdmax or the range of θS±δθSavdmax at the same time at future time tz. Then, the communication satellite 110 moving north operates the propulsion device 111 to change the passing timing.

[0048] As a result of updating the orbital information of a communications satellite that has taken evasive action, there is a possibility that the communications satellite may face a risk of colliding with a communications satellite in an orbital plane where there was no risk of collision initially. However, by using machine learning to learn the impact of evasive action on orbital information using AI, it is possible to avoid collisions with communications satellites after evasive action has been taken.

[0049] When the communication satellites 110 in each orbital plane fly above the equator and move northward, the phases are shifted by 360 / (m×n) degrees.

[0050] Since the timing of passing over the equator differs for each communications satellite, it becomes easier to select an initial configuration that will avoid collisions during normal operation.

[0051] *** Summary of the first embodiment *** The emergence of mega-constellations and the proliferation of debris have dramatically increased the number of objects in orbit, increasing the risk of collisions in space. Therefore, a method to avoid collisions is needed. The first embodiment provides a collision avoidance method for taking evasive action by machine learning of artificial intelligence (AI) in a communication satellite constellation forming a mesh-type communication network.

[0052] The first embodiment provides a collision avoidance method in which collisions between satellites moving northward or between satellites moving southward are eliminated by changing the satellite flight positions for each orbital plane, and when a collision between a satellite moving northward and a satellite moving southward is predicted, the satellite moving northward takes collision avoidance action. In the first embodiment, satellites in front and behind the same orbital plane form a circular communication network. In addition, satellites in adjacent orbits in the longitude direction form a circular or spiral communication network in the longitude direction. This forms a mesh-like communication network. The first embodiment provides the following collision avoidance method. When a collision between a satellite moving north and a satellite moving south is predicted, the satellite moving north operates its propulsion device to avoid the collision. Furthermore, the communication satellite that has avoided the collision notifies updated orbit information via a mesh communication network to avoid collision with a communication satellite in another orbital plane. Then, the artificial intelligence (AI) of the analysis device performs machine learning to update the range of intersections between the orbital planes.

[0053] The first embodiment is an example of a preferred embodiment and is not intended to limit the technical scope of the present disclosure. The first embodiment may be implemented in part or in combination with other embodiments. [Explanation of symbols]

[0054] 100 satellite constellation system, 101 satellite constellation, 102 communication satellite group, 103 orbit group, 104 orbit, 109 Earth, 110 communication satellite, 111 propulsion device, 112 attitude control device, 113 satellite control device, 114 communication system, 115 front and rear communication device, 116 left and right communication device, 117 ground communication device, 118 analysis device, 119 storage device, 120 ground equipment, 121 satellite control device, 122 communication device.

Claims

1. A satellite constellation that forms a plurality of orbital planes in which the longitudinal components of normal vectors differ from each other, a plurality of communications satellites for forming the plurality of orbital planes; a self-contained satellite group, each of the plurality of communication satellite groups, is composed of a plurality of communication satellites flying in a self-contained orbital plane formed by the self-contained satellite group; Each of the plurality of communication satellites is a self-satellite, a communication system for receiving orbital data of each communication satellite of the satellite constellation by communicating with each of the communication satellites on the left, right, front and rear of the own satellite; an analysis device that detects a collision risk of the own satellite and a counterpart satellite flying in a counterpart orbital plane colliding at an intersection of the own orbital plane and the counterpart orbital plane by analyzing orbit data of the own satellite and the received orbital data, and selects either the own satellite or the counterpart satellite as an avoidance satellite when the collision risk is detected; a propulsion device that changes a speed of the own satellite when the own satellite is selected as the avoidance satellite, thereby changing a passing timing of the own satellite passing through the node; Equipped with the analysis device generates difference data indicating a difference between pre-update orbit data, which is the orbit data of the own satellite before the pass timing is changed, and updated orbit data, which is the orbit data of the own satellite after the pass timing is changed, when the own satellite changes the pass timing; The communication system transmits the updated orbit data or the difference data to each communication satellite of the satellite constellation by communicating with each of the communication satellites on the front, rear, left and right of the own satellite. Satellite constellation.

2. The analysis device detects, as the collision risk, the presence of the other satellite that passes within a range of a design tolerance from the node at a future time when the own satellite passes the node. The satellite constellation of claim 1 .

3. The analysis device has an artificial intelligence that machine-learns the deviation of the intersection based on past intersections of the own orbital plane and each of the partner orbital planes, and detects, as the collision risk, the existence of the partner satellite that passes within the deviation range from the intersection at a future time when the own satellite passes through the intersection, by the artificial intelligence after machine learning. The satellite constellation of claim 1 .

4. The analysis device has an artificial intelligence that machine-learns a maximum deviation of the intersection based on past intersections of the own orbital plane and each of the partner orbital planes, and detects, as the collision risk, the existence of the partner satellite that passes within the range of the maximum deviation from the intersection at a future time when the own satellite passes through the intersection, by the artificial intelligence after machine learning. The satellite constellation of claim 1 .

5. When the satellite itself changes the passing timing, the communication system communicates with each of the communication satellites in the front, rear, left and right directions, and transmits updated orbit data after the passing timing has been changed, or difference data indicating a difference between the pre-update orbit data before the passing timing is changed and the updated orbit data, to each communication satellite in the satellite constellation. A satellite constellation according to any one of claims 1 to 4.

6. The analysis device analyzes the pre-update orbit data and the post-update orbit data or the difference data and the orbit data of each communication satellite to detect a new collision risk. A satellite constellation as claimed in claim 5.

7. the plurality of communications satellites is a constellation of n communications satellites; each of the n communications satellite constellations is made up of m communications satellites; (n x m) communication satellites move north over the equator, shifting their phase from each other by (360 / (n x m)) degrees. A satellite constellation according to any one of claims 1 to 6.

8. A communications satellite for use in a satellite constellation according to any one of claims 1 to 7.

9. 1. An automatic collision avoidance method for a satellite constellation that forms a plurality of orbital planes in which longitudinal components of normal vectors differ from each other, comprising: the satellite constellation comprises a group of a plurality of communication satellites for forming the plurality of orbital planes; a self-contained satellite group, each of the plurality of communication satellite groups, is composed of a plurality of communication satellites flying in a self-contained orbital plane formed by the self-contained satellite group; Each of the plurality of communication satellites includes a communication system, an analysis device, and a propulsion device; the communication system receives orbital data of each communication satellite of the satellite constellation by communicating with each of the communication satellites on the front, rear, left and right of the own satellite; the analysis device detects a collision risk of the own satellite and a counterpart satellite flying in a counterpart orbital plane colliding at an intersection of the own orbital plane and the counterpart orbital plane by analyzing the orbital data of the own satellite and the received orbital data, and selects either the own satellite or the counterpart satellite as an avoidance satellite when the collision risk is detected; the propulsion device changes a speed of the own satellite when the own satellite is selected as the avoidance satellite, thereby changing a passing timing at which the own satellite passes through the node; the analysis device generates difference data indicating a difference between pre-update orbit data, which is the orbit data of the own satellite before the pass timing is changed, and updated orbit data, which is the orbit data of the own satellite after the pass timing is changed, when the own satellite changes the pass timing; The communication system transmits the updated orbit data or the difference data to each communication satellite of the satellite constellation by communicating with each of the communication satellites on the front, rear, left and right of the own satellite. Automatic collision avoidance method.

10. The analysis device has an artificial intelligence that machine-learns a maximum deviation of the intersection based on past intersections of each of the partner orbital planes of the own orbital plane, and detects, as the collision risk, the existence of the partner satellite that passes within the range of the maximum deviation from the intersection at a future time when the own satellite passes through the intersection, by the artificial intelligence after machine learning.

10. The automatic collision avoidance method of claim 9.

11. When the timing at which the own satellite passes through the intersection is changed, the communication system communicates with the communication satellites on the front, rear, left, and right sides, and transmits difference data indicating a difference between the orbit data of the own satellite and the updated orbit data to each communication satellite of the satellite constellation.

11. The automatic collision avoidance method according to claim 9 or 10.

12. The analysis device detects a new collision risk based on the updated trajectory data. The method of automatic collision avoidance according to claim 11.

Images