JP2020032874A - System and method for controlling position and attitude of artificial satellite - Google Patents

Abstract

To control a relative position and a relative attitude between artificial satellites by a magnetic force alone, without making a use limited to orbit around a celestial body where terrestrial magnetism exists.SOLUTION: A system 1 for controlling a position and an attitude of an artificial satellite controls a relative position and a relative attitude between a master satellite 2 and a slave satellite 3. The master satellite 2 and the slave satellite 3 have triaxial magnetic field generating sources 21 and 31 and control parts 24 and 34, respectively. Each of the control parts 24 and 34 controls a magnetic flux density vector of a magnetic field generated by each of the triaxial magnetic field generating sources 21 and 31, depending on the relative position and the relative attitude between the master satellite 2 and the slave satellite 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an artificial satellite position / attitude control system and an artificial satellite position / attitude control method suitable for, for example, formation flight control of a micro satellite.

  For controlling the relative position and relative attitude between two artificial satellites, a propulsion device such as a thruster and an attitude control device such as a reaction wheel are used. However, these devices have large capacities and weights, and are difficult to mount especially on small satellites. Artificial satellites that lack such resources have been replaced with lightweight, compact, and simple devices, such as using magnetic torquers and magnetic force generators (see Patent Document 1, for example).

JP 2003-212197 A

  Even when magnetic force is used for relative position / relative attitude control as in Patent Document 1, control of all axes of relative position / relative attitude is not controllable, and a separate propulsion device or attitude control device is required.

  Applications of magnetic torquers are limited to orbits of celestial bodies where geomagnetism exists.

  In view of the circumstances described above, an object of the present invention is to control the position and attitude of an artificial satellite that can control the relative position and relative attitude between the artificial satellites only by magnetic force without being limited to the above-mentioned orbit. An object of the present invention is to provide a system and a position / attitude control method for an artificial satellite.

In order to achieve the above object, a position / attitude control system for an artificial satellite according to one embodiment of the present invention is a system for controlling a relative position and an relative attitude between a first artificial satellite and a second artificial satellite, Each of the first and second satellites has a three-axis magnetic field source and a control unit, and each of the control units includes a relative position between the first and second satellites and A magnetic flux density vector of a magnetic field generated by each of the three-axis magnetic field sources is controlled according to the relative attitude.
Thereby, the relative position and relative attitude between the satellites can be controlled only by the magnetic force, without being limited to the orbit of the celestial body where the geomagnetism exists.

Each of the control units is generated between the first artificial satellite and the second artificial satellite when the second artificial satellite is translated relative to the first artificial satellite. In a preferred embodiment, the magnetic flux density vector of the magnetic field generated by each of the three-axis magnetic field sources is time-divisionally controlled so as to minimize the torque.
Thereby, the translation can be stably performed only by the magnetic field.

Each of the control units is configured such that when the second artificial satellite is translated relative to the first artificial satellite, the second artificial satellite repeats a tack and moves in a zigzag manner. It is preferable that the magnetic flux density vector of the magnetic field generated by the three-axis magnetic field generation source be time-divisionally controlled.
Thus, the translation can be stably performed in an arbitrary direction only by the magnetic field.

In addition to the first and second satellites, the satellite includes one or more third satellites having the three-axis magnetic field generation source and the control unit, and each of the control units includes the first artificial satellite. Time-division control of a magnetic flux density vector of a magnetic field generated by each of the three-axis magnetic field sources according to a relative position and a relative attitude between a satellite, the second artificial satellite, and the third artificial satellite. This is a preferred form.
Thereby, formation flight control by many satellites becomes possible.

The control unit of the third artificial satellite generates a three-axis magnetic field of the third artificial satellite when controlling a relative position and a relative attitude between the first artificial satellite and the second artificial satellite. It is a preferable mode to control so that a magnetic field is not generated from the source.
This enables accurate formation flight control by a large number of satellites.

The position / attitude control method for an artificial satellite according to one embodiment of the present invention is a method for controlling the relative position and the relative attitude between a first artificial satellite and a second artificial satellite, A three-axis magnetic flux density vector generated by each of the three-axis magnetic field sources mounted on the artificial satellite is controlled according to a relative position and a relative attitude between the first artificial satellite and the second artificial satellite. By doing so, the relative position vector and the relative attitude vector of the second artificial satellite with respect to the first artificial satellite are controlled.
Thereby, the relative position and relative attitude between the satellites can be controlled only by the magnetic force, without being limited to the orbit of the celestial body where the geomagnetism exists.

In a satellite constellation made up of one or more third satellites equipped with the three-axis magnetic field generation source in addition to the first satellite and the second satellite, the first satellite In a preferred embodiment, the relative position and the relative attitude between the second artificial satellite and the third artificial satellite are time-divisionally controlled.
Thereby, formation flight control by many satellites becomes possible.

The first artificial satellite is put into an orbit orbiting an celestial body, and the second artificial satellite is put into a record orbit in which the distance from the first artificial satellite fluctuates in a cycle of orbital rotation. It is a preferred embodiment that the sensitivity for controlling the relative position and relative attitude of the artificial satellite is changed in the period of the orbital orbit.
Thus, a highly accurate relative elliptical orbit by two artificial satellites can be realized with a simple control.

  According to the present invention, it is possible to control relative positions and relative attitudes between artificial satellites only by magnetic force without being limited to applications in orbits of celestial bodies where geomagnetism exists.

It is a figure showing composition of a position and attitude control system of an artificial satellite concerning one embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of a three-axis magnetic field generation source of the artificial satellite illustrated in FIG. 1. FIG. 4 is a diagram for explaining control of a magnetic flux density vector in a three-axis magnetic field generation source. FIG. 4 is a diagram for explaining the principle of translational force generation between two three-axis magnetic field generation sources. 11 is a graph showing a simulation result of a range of a force generated between a parent satellite and a child satellite when the generation of torque is minimized. It is explanatory drawing (the 1) of the formation flight control by time division. It is explanatory drawing (the 2) of the formation flight control by time division. It is explanatory drawing (the 3) of the formation flight control by time division. FIG. 3 is an explanatory diagram of formation flight control by a number of satellites. It is a flowchart for demonstrating control of a parent satellite including communication with a child satellite. It is a flowchart for demonstrating control of a child satellite including communication with a parent satellite. It is a flowchart for demonstrating the control by three or more satellites.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<Configuration of satellite position and attitude control system>
FIG. 1 is a diagram showing a configuration of a satellite position / attitude control system according to an embodiment of the present invention.
As shown in FIG. 1, an artificial satellite position / attitude control system 1 includes a first artificial satellite (this is called a "parent satellite") 2 and a second artificial satellite (this is called a "child satellite"). And 3) controlling the relative position and relative attitude with respect to 3. Hereinafter, the artificial satellite may be simply referred to as a satellite.

  The parent satellite 2 includes a three-axis magnetic field generation source 21, a switch unit 22, a communication unit 23, a control unit 24, and a determination unit 25.

  Similarly, the satellite 3 also includes a three-axis magnetic field source 31, a switch unit 32, a communication unit 33, a control unit 34, and a determination unit 35.

  As shown in FIG. 2, the three-axis magnetic field sources 21 and 31 have electromagnets 21a and 31a oriented in a first axial direction and electromagnets 21b and 31b oriented in a second axial direction, respectively. Although the electromagnets 21a and 31a and the electromagnets 21b and 31b are perpendicular to each other in the drawing, they need not be perpendicular unless they are coaxial. In the figure, two electromagnets 21a and 31a and two electromagnets 21b and 31b are shown for simplicity of description, but the number is not limited to two. The three-axis magnetic field sources 21 and 31 may have three or more electromagnets.

  The switches 22 and 32 are configured to selectively energize the three-axis magnetic field sources 21 and 31 under the control of the controllers 24 and 34, respectively.

  The communication units 23 and 33 communicate with each other to control the relative position and relative attitude between the parent satellite 2 and the child satellite 3.

  The control units 24 and 34 respectively provide a sensor for detecting a relative position and a relative attitude between the parent satellite 2 and the child satellite 3, and a relative position between the parent satellite 2 and the child satellite 3 which are detection results of the sensors. The three-axis magnetic flux density vectors generated by the three-axis magnetic field sources 21 and 31 are controlled according to the relative attitude. Thereby, all or a part of the relative three-axis position vector and the relative three-axis attitude vector of the child satellite 3 with respect to the parent satellite 2 are controlled.

  In the three-axis magnetic field sources 21 and 31, the energization of each of the electromagnets 21 a and 21 b and the electromagnets 31 a and 31 b is controlled on / off so that the three-axis magnetic field source 21 of the parent satellite 2 and the three-axis magnetic field The source 31 can be attracted or repelled.

  Further, as shown in FIG. 3, in each of the three-axis magnetic field sources 21 and 31, both the electromagnets 21a and 31a oriented in the first axial direction and the electromagnets 21b and 31b oriented in the second axial direction are simultaneously turned on. This is the same as turning on one oblique virtual electromagnet 21c, 31c. This makes it possible to generate an oblique magnetic flux density vector without physically rotating the electromagnet.

  As shown in FIG. 4, oblique magnetic flux density vectors are generated in the triaxial magnetic field sources 21 and 31, respectively. Here, each triaxial magnetic field generation source can be regarded as a pair of positive and negative magnetic poles. Symbols A, B, C, and D indicate the force of attracting and repelling the magnetic poles of the three-axis magnetic field source 21 at the magnetic poles of the three-axis magnetic field source 31, and the symbol 41 indicates the resultant force of A, B, C, and D. Is shown. Symbols E, F, G, and H indicate the force of attracting and repelling the magnetic poles of the triaxial magnetic field source 31 at the magnetic poles of the triaxial magnetic field source 21, and the symbol 43 indicates the resultant force of E, F, G, and H. Is shown. Reference numeral 42 denotes a torque generated by the triaxial magnetic field generation source 21, and reference numeral 44 denotes a torque generated by the triaxial magnetic field generation source 31.

  When an oblique magnetic flux density vector is generated, not only a force in the attracting direction but also a lateral force (translational force) and a torque are generated between the two three-axis magnetic field generating sources. When adjusted, the generation of torque can be minimized. That is, the translational force can be generated by minimizing the torque acting on the three-axis magnetic field sources 21 and 31. Further, by appropriately generating the torque, the attitude control between the parent satellite 2 and the child satellite 3 can be performed.

  FIG. 5 shows a range of force generated between the parent satellite 2 and the child satellite 3 when the generation of torque is minimized by controlling the magnetic flux density vector. The inside of the regions 51, 52, 53, 54 is the range of the force generated between the parent satellite 2 and the child satellite 3. The area 51 is a case where the three-axis magnetic field sources of the parent satellite 2 and the child satellite 3 generate a large magnetic field, the area 52 is slightly larger, the area 53 is slightly smaller, and the area 54 is smaller. No force is generated in a hatched range 55, that is, a range in which the translational force is greater than a certain amount with respect to the force in the attracting direction. Therefore, in the present embodiment, formation flight control is performed by time division described below.

<Formation flight control by time division>
Reference numeral 61 in FIG. 6A indicates a movement vector desired by the satellite 3. The child satellite 3 obtains the movement vector 61 by performing time-division control so that the movement vector becomes zigzag along the movement vector 61.
Reference numeral 62a in FIG. 6A indicates a range of a force generated in the satellite 3 when the generation of torque is minimized by controlling the magnetic flux density vector, and the satellite 3 is initially positioned at a predetermined position in the range 62a. A movement vector 61a is obtained. The predetermined position is typically a contact point of a tangent on the movement vector 61 side among tangents from the position of the first slave satellite 3 to the outer periphery of the range 62a.
Reference numeral 62b in FIG. 6B indicates a range of the force generated in the satellite 3 when the generation of the torque is minimized at the end point of the movement vector 61a. Next, the satellite 3 moves toward a predetermined position in the range 62b. The movement vector 61b is obtained. Here, the movement vector 61a is in a direction away from the movement vector 61, and the movement vector 61b is in a direction approaching the movement vector 61. In the present invention, the change of the vector in the direction from the movement vector 61a to the movement vector 61b is called tack. The child satellite 3 moves zigzag along the movement vector 61 by repeating the tack.
By repeating the above time division control, the child satellite 3 obtains the movement vector 61 as shown in FIG. 6C.

The reason for performing the control in a time-division manner is that the superposition may not be effective in the case of the magnetic force.
At the same time as the above-mentioned orbit control, attitude control is also possible by controlling the torque 63 between the parent satellite 2 and the child satellite 3 in a direction in which no translational force is generated.

According to the present invention, the formation flight control is possible even for a large number of satellites by performing the time-division control that enables the relative orbit control and the attitude control only by the magnetic force.
FIG. 7 shows an example of formation flight control using a large number of satellites.
The near satellites 71a and 71b and the near satellites 72a and 72b can be controlled by the magnetic flux density vector, but since the magnetic force is inversely proportional to the square of the distance, there is no effect between the satellites 71a and 71b at a long distance and the satellites 72a and 72b. . The magnetic force generated by the satellites 71a and 71b and the satellites 72a and 72b does not affect the satellite 73 that does not generate a magnetic field.
Therefore, in the present invention, orbit control and attitude control of a large number of satellites can be performed by performing formation flight control by a large number of satellites in a time division manner.

<Control between satellites>
8A and 8B show an example of control including communication between the parent satellite 2 and the child satellite 3. In this example, the child satellite 3 is in a form of control dependent on the parent satellite 2, but two satellites (parent satellite and child satellite) may be controlled by control of another satellite having a control function. Control may be performed in another form.

The control unit 24 of the parent satellite 2 causes the determination unit 25 to determine the distance between the parent satellite 2 and the child satellite 3 (Step A1).
The control unit 24 calculates a target relative position, speed, and attitude based on the determination result (step A2).
The control unit 24 considers the geomagnetism and generates the least torque, and obtains the magnetic flux density vector closest to the target translational motion by using a built-in list or an approximate expression (step A3). By having a list, it is possible to provide an approximate control input with a simple operation / storage device. Further, by using an approximate expression, it is possible to provide an approximate control input with a simple arithmetic device. In any case, the calculation load can be reduced.
The control unit 24 transmits the data of the magnetic flux density vector obtained in step A3 to the satellite 3 via the communication unit 23 (step A4), and then controls the switch unit 22 at a predetermined timing to control the three-axis magnetic field generation source. 21 generates a predetermined magnetic flux density vector (step A5).

  Upon receiving the data of the magnetic flux density vector via the communication unit 33 (step B1), the control unit 34 of the slave satellite 3 controls the switch unit 32 at a timing synchronized with the master satellite 2 to generate a three-axis magnetic field. A predetermined magnetic flux density vector is generated from the source 31 (step B2).

Thereafter, the control unit 24 of the parent satellite 2 causes the determination unit 25 to determine whether the parent satellite 2 and the child satellite 3 have approached the target (Step A6).
When approaching the target, the control unit 24 ends a series of control operations. On the other hand, when the target is not approaching the target, the control unit 24 repeats the processing of steps A1 to A5. The child satellite 3 executes the processing of steps B1 and B2 in response to this.

FIG. 9 shows an example of control by three or more satellites. The satellite that controls three or more satellites (this is called a “control satellite”) may be one of these satellites, or may be a different satellite from these satellites. Is also good.
The control satellite selects a pair of two adjacent satellites (step C1). In the example of FIG. 7, the pair of two adjacent satellites is a pair of nearby satellites 71a and 71b and a pair of nearby satellites 72a and 72b. When a pair is selected, such as between the nearby satellites 71a and 71b and the nearby satellites 72a and 72b, one or more uncontrolled satellites 73 are sandwiched between these pairs. Further, in the pair selection subsequent to the pair selection, it is preferable to preferentially select from the satellites not previously selected.
For the selected satellite pair (step C2), the control satellite causes the two pairs of satellites to perform, for example, the control shown in FIGS. 8A and 8B (step C3).
On the other hand, the control satellite causes the pair of unselected satellites (step C2) to perform control not to generate any magnetic field (step C4).

Thereafter, the control satellite keeps the situation for a while (step C5). This holding time is determined by a time constant such as the size of the satellite.
The control satellite repeats the above steps C1 to C5 until the target relative position and relative speed are sufficiently close to each other (step C6). The determination of the target relative position and relative speed may be performed by integrating the determination results from the respective satellites, or the control satellite may include another observation unit such as an imaging unit.

  As described above, in the position and attitude control system 1 of the satellite according to the present embodiment, the relative position and the relative attitude between the satellites can be controlled only by the magnetic force.

<Others>
The present invention is not limited to the examples shown in the above embodiments, and various modifications and applications are possible.
For example, in the position and attitude control system 1 of the artificial satellite, the parent satellite 2 is put into an orbit orbiting the celestial body, and the child satellite 3 is moved into a record orbit (Cartwheel type) in which the distance from the parent satellite 2 fluctuates in the orbital period. (Orbit), and the sensitivity for controlling the relative position and relative attitude of the satellite 3 may be changed in the period of the orbit. Thereby, a highly accurate relative elliptical orbit by the parent satellite 2 and the child satellite 3 performing the formation flight can be realized with a simple control.

  The sensitivity control described above can be applied to formation flight control using a large number of satellites. In this case, the orbit is inserted so that the phase in which the sensitivity periodically fluctuates is shifted between the plurality of slave satellites 3, and the relative position and the relative attitude of the slave satellite 3 in the high sensitivity state are time-divisionally controlled. Is also good. Accordingly, a highly accurate relative elliptical orbit by the parent satellite 2 and the plurality of child satellites 3 performing the formation flight can be realized with a simple control.

  Even if the attitude control means is separately provided so that the parent satellite 2 keeps the designated orientation with respect to the inertial space, the relative position and the relative attitude of the child satellite 3 may be controlled after controlling the absolute attitude of the parent satellite 2. Good. This can be used, for example, when the parent satellite 2 wants to fix its attitude to maintain high gain communication.

  Further, the moment of inertia of the parent satellite 2 is made sufficiently large with respect to the moment of inertia of the child satellite 3 so that the parent satellite 2 keeps the designated orientation with respect to the inertial space, and the attitude of the parent satellite 2 is hardly changed. The relative position and relative attitude of the satellite 3 may be controlled.

  In addition, even if a separate attitude control means is not provided, by controlling the magnetic flux density vector of the three-axis magnetic field generating source of the parent satellite and the child satellite, a torque is generated between the parent satellite and the geomagnetism, and the absolute After controlling the attitude, the relative position and relative attitude of the satellite 3 may be controlled.

  The parent satellite 2 may separately include an orbit control unit, and may control the relative position and the relative attitude of the child satellite 3 while maintaining the orbit of the parent satellite 2.

  Further, the mass of the parent satellite 2 may be made sufficiently large with respect to the mass of the child satellite 3, and the relative position and the relative attitude of the child satellite 3 may be controlled without substantially changing the orbit of the parent satellite 2.

  The three-axis magnetic field generation source may be configured to approximately generate the three-axis magnetic field by independently controlling the current flowing through the coils of the three electromagnets.

  Instead of the parent satellite 2 performing the control operation, the control operation may be shared between the parent satellite 2 and the child satellite 3. This makes it possible to distribute the computational load.

1 attitude control system 2 parent satellite (first artificial satellite)
3 satellites (second artificial satellite)
21, 31 3-axis magnetic field source 24, 34 control unit

Claims (8)

In a system for controlling a relative position and a relative attitude between a first satellite and a second satellite,
Each of the first and second satellites has a three-axis magnetic field source and a control unit,
Each of the control units controls a magnetic flux density vector of a magnetic field generated by each of the three-axis magnetic field sources according to a relative position and a relative attitude between the first artificial satellite and the second artificial satellite. Satellite position and attitude control system. Each of the control units is generated between the first artificial satellite and the second artificial satellite when the second artificial satellite is translated relative to the first artificial satellite. The position / attitude control system for an artificial satellite according to claim 1, wherein a magnetic flux density vector of a magnetic field generated by each of the three-axis magnetic field generation sources is controlled so as to minimize torque. Each of the control units is configured such that when the second artificial satellite is translated relative to the first artificial satellite, the second artificial satellite repeats a tack and moves in a zigzag manner. The position / attitude control system for an artificial satellite according to claim 2, wherein the magnetic flux density vector of the magnetic field generated by the three-axis magnetic field generation source is time-divisionally controlled. In addition to the first and second satellites, the satellite has one or more third satellites having the three-axis magnetic field generation source and the control unit,
Each of the control units controls a magnetic field generated by each of the three-axis magnetic field sources according to a relative position and a relative attitude between the first artificial satellite, the second artificial satellite, and the third artificial satellite. The position / attitude control system for an artificial satellite according to claim 1, wherein the magnetic flux density vector is time-divisionally controlled. The control unit of the third artificial satellite generates a three-axis magnetic field of the third artificial satellite when controlling a relative position and a relative attitude between the first artificial satellite and the second artificial satellite. The position / attitude control system for an artificial satellite according to claim 4, wherein control is performed so that a magnetic field is not generated from the source.   In a method of controlling a relative position and a relative attitude between a first artificial satellite and a second artificial satellite, each of the three-axis magnetic field sources mounted on the first and second artificial satellites generates 3 Controlling the magnetic flux density vector of the axis according to the relative position and relative attitude between the first artificial satellite and the second artificial satellite, so that the second artificial satellite with respect to the first artificial satellite A satellite position and attitude control method that controls the relative position vector and relative attitude vector.   In a satellite constellation made up of one or more third satellites equipped with the three-axis magnetic field generation source in addition to the first satellite and the second satellite, the first satellite The position / attitude control method for an artificial satellite according to claim 6, wherein relative position and relative attitude between the second artificial satellite and the third artificial satellite are time-divisionally controlled.   The first artificial satellite is put into an orbit orbiting an celestial body, and the second artificial satellite is put into a record orbit in which the distance from the first artificial satellite fluctuates in a cycle of orbital rotation. The position / attitude control method for an artificial satellite according to claim 6, wherein the sensitivity for controlling the relative position and relative attitude of the artificial satellite is changed in a period of orbital orbit.

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