JP6945394B2 - Sun capture device, control system and space structure - Google Patents

Description

The present invention relates to sun capture devices, control systems and space structures.

As a sensor for detecting the attitude angle mounted on an artificial satellite, there are a sun sensor, a stellar sensor, and the like. Conventionally, a sun sensor or a stellar sensor is used to direct toward the sun. In the unlikely event that a sensor fails, there is an increasing demand for robustness and survivability, such as being able to capture the sun and secure power. Further, in recent years, the number of artificial satellites having restrictions on on-board equipment such as small satellites is increasing, and the reduction of sensors is also an issue.

Patent Document 1 describes a technique for capturing the sun by using a dedicated solar cell or a solar cell for generating electric power as a solar sensor. Specifically, after rotating the spacecraft around the X-axis and stopping it at the position where the output of the sun sensor is maximized, the spacecraft is rotated around the Y-axis and at the position where the output of the sun sensor is maximized. A technique for controlling the spacecraft to a sun-oriented attitude by stopping it is described.

Japanese Unexamined Patent Publication No. 1-182719

In the technique described in Patent Document 1, it takes time to capture the sun because the spacecraft must be rotated about the X-axis and then the spacecraft must be further rotated about the Y-axis.

An object of the present invention is to capture the sun quickly.

The sun trapping device according to one aspect of the present invention is
The current generated from the solar cell when the space structure on which the solar cell is mounted rotates about a rotation axis that is inclined at an arbitrary inclination angle with respect to the direction perpendicular to the light receiving surface of the solar cell. An acquisition unit that acquires different current values depending on the rotation angle around the rotation axis,
It is provided with a calculation unit for calculating the sun direction angle with respect to the rotation axis from the inclination angle and the current value acquired by the acquisition unit.

In the present invention, the sun can be captured by rotating the space structure around a rotation axis that is tilted at an arbitrary tilt angle with respect to the direction perpendicular to the light receiving surface of the solar cell. That is, the sun can be captured quickly.

The block diagram which shows the structure of the artificial satellite which concerns on Embodiment 1. FIG. The block diagram which shows the structure of the sun trapping apparatus which concerns on Embodiment 1. FIG. The figure which shows the operation of the control system which concerns on Embodiment 1. FIG. The figure which shows the operation of the control system which concerns on Embodiment 1. FIG. The figure which shows the operation of the control system which concerns on Embodiment 1. FIG. The figure which shows the operation of the control system which concerns on Embodiment 1. FIG. The figure which shows the operation of the control system which concerns on Embodiment 1. FIG. The graph which shows the example of the maximum generated current, the average generated current and the minimum generated current which concerns on Embodiment 1. FIG. The graph which shows the example of the difference between the maximum generated current and the minimum generated current which concerns on Embodiment 1. FIG. The figure which shows the operation of the control system which concerns on Embodiment 1. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, the same or corresponding parts are designated by the same reference numerals. In the description of the embodiment, the description will be omitted or simplified as appropriate for the same or corresponding parts. The present invention is not limited to the embodiments described below, and various modifications can be made as needed. For example, the embodiments described below may be partially implemented.

Embodiment 1.
The present embodiment will be described with reference to FIGS. 1 to 10.

*** Explanation of configuration ***
The configuration of the artificial satellite 10 according to the present embodiment will be described with reference to FIGS. 1 and 2.

The artificial satellite 10 includes a control system 11 and a controlled plant 12 including dynamics such as attitude dynamics.

The control system 11 controls the attitudes of the solar cell 21, the sun capturing device 31 that calculates the direction of the sun based on the generated power of the solar cell 21, and the artificial satellite 10 according to the calculation result of the sun capturing device 31. The controller 41 is provided.

Although not essential, the control system 11 includes a star sensor 22, a sun sensor 23, a sun direction calculator 32 that calculates the sun direction based on the observation results of the star sensor 22 or the sun sensor 23, and a sun direction calculator. A controller 42 that controls the attitude of the artificial satellite 10 according to the calculation result of 32 is further provided.

The control system 11 further includes an actuator 51 that converts a command from the controller 41 into a physical action applied to the controlled plant 12 in order to realize posture control by the controllers 41 and 42.

The sun capture device 31 is a computer or a microcomputer. Although not shown, the sun capture device 31 includes hardware such as a processor and memory. The processor is, for example, a CPU. "CPU" is an abbreviation for Central Processing Unit. The memory is, for example, a flash memory or RAM. "RAM" is an abbreviation for Random Access Memory.

The sun capture device 31 includes an acquisition unit 33 and a calculation unit 34 as functional elements. The functions of the acquisition unit 33 and the calculation unit 34 are realized by software. The program that realizes the functions of the acquisition unit 33 and the calculation unit 34 is read from the memory into the processor and executed by the processor.

*** Explanation of operation ***
In addition to FIGS. 1 and 2, the operation of the control system 11 according to the present embodiment will be described with reference to FIGS. 3 to 10. The operation of the control system 11 corresponds to the attitude control method according to the present embodiment.

In each figure, S is the sun direction vector, X _B is the satellite coordinate system X axis, Y _B is the satellite coordinate system Y axis, Z _B is the satellite coordinate system Z axis, ω _s is the sun direction axis, and α is an arbitrary angle. δ represents the angle in the direction of the sun, and θ represents the rotation angle. An object of the present embodiment is to direct the sun-directed axis toward the sun. The angle δ in the direction of the sun corresponds to the deviation in the direction of the sun from the axis of the sun.

In the present embodiment, the control system 11 directs the artificial satellite 10 toward the sun as shown in FIG. 3 based on the electric power generated from the solar cell 21. The specific operation is as follows.

First, as shown in FIG. 4, the control system 11 rotates the artificial satellite 10 around _{the ω s} axis tilted by an arbitrary angle α with respect to the light receiving surface of the solar cell 21.

As shown in FIG. 5, when the angle formed by the solar direction vector S and the −Z _B axis is the smallest, that is, the posture in which the generated current of the solar cell 21 is maximum, the rotation angle θ around the _{ω s axis is 0.} As shown in FIG. 6, the current generated when the rotation angle θ is 180 ° is the smallest when the posture is set to °.

_{The relationship between the ω s} axis seen from the satellite coordinate system at this time, the solar direction vector S, and the generated current is shown in FIGS. 7 and 8. A _max represents the maximum generated current, A _ave represents the average generated current, and A _min represents the minimum generated current.

Here, the rotation angle θ about the omega _s axis, the angle between the -Z _B axis and omega _s axis alpha, and the sun direction vector S with a δ angle between sun direction vector S and omega _s shaft Expressed as follows.

Furthermore, by taking the inner product of the unit vector e and the sun direction vector S of -Z _B axis, the generation current A (theta) of the rotation angle theta, sunlight perpendicularly on the light receiving surface of the solar cell 21 It can be expressed as follows using the generated current A _{0 in the case of hitting.}

_{The maximum generated current A max} obtained when the rotation angle θ is 0 °, the _{average generated current A ave} obtained when the rotation angle θ is 90 ° or 270 °, and the average generated current A ave obtained when the rotation angle θ is 180 °. The minimum generated current A _min is as follows.

In this embodiment, the acquiring unit 33 of the sun acquisition device 31, the current generated from the solar cell 21 when the satellite 10 is rotated about the omega _s axis, the rotation angle around the omega _s axis θ Get different current values depending on. The ω _s axis is a rotation axis that is inclined at an arbitrary inclination angle α with respect to the vertical direction of the light receiving surface of the solar cell 21. The calculation unit 34 of the sun capture device 31 specifies _{at least the maximum value A max} and the minimum value A _{min from the current values acquired by the acquisition unit 33.}

The following equation is obtained by calculating the difference ΔA between the _{maximum generated current A max} and the minimum generated current A _min as shown in FIG. 9 and _{dividing by the average generated current A ave.}

Since the _{angle α formed by the ω s} axis and the −Z _B axis is a known quantity, the angle δ formed by the sun direction vector S and the ω _s axis can be calculated by the following equation.

In the present embodiment, the calculation unit 34 of the sun capture device 31 calculates the sun direction angle δ with respect _{to the ω s axis from the inclination angle α and the current value acquired by the acquisition unit 33.} Therefore, the calculation unit 34 calculates at least a part of the above-mentioned formulas, or executes a process equivalent to the calculation of the formulas.

Specifically, the calculation unit 34 has _{a maximum value A max} and a minimum value A _{min of} the current generated from the solar cell 21 when _{the artificial satellite 10 rotates about the ω s axis acquired by the acquisition unit 33.} using the difference ΔA and the average a _ave and calculates the solar direction angle [delta].

Alternatively, assuming that the current value of the current generated from the solar cell 21 is the maximum value A _max when the rotation angle θ is 0 °, the calculation unit 34 determines that the rotation angle θ acquired by the acquisition unit 33 is The solar direction angle δ is calculated using the difference between the current value when the rotation angle θ is 180 ° and the current value when the rotation angle θ is 180 ° and the current value when the rotation angle θ is 90 ° or 270 °. ..

Finally, the control system 11 controls the attitude of the artificial satellite 10 so that the angle δ approaches 0 ° based on the calculated angle δ in the direction of the sun, so that the ω _s axis is set to the sun as shown in FIG. Turn in the direction.

By repeating the above operation, the artificial satellite 10 can always be directed toward the sun.

*** Explanation of the effect of the embodiment ***
In the present embodiment, the sun can be captured by rotating the artificial satellite 10 around a rotation axis that is inclined at an arbitrary inclination angle α with respect to the vertical direction of the light receiving surface of the solar cell 21. That is, the sun can be captured quickly. Therefore, the attitude of the artificial satellite 10 can be quickly controlled in the direction of the sun. That is, it is almost always possible to direct the artificial satellite 10 toward the sun.

In the present embodiment, the control system 11 captures the sun by using the solar cell 21 mounted on the artificial satellite 10 as a highly reliable sensor. Specifically, the control system 11 directs the artificial satellite 10 toward the sun based on the electric power generated by the solar cell 21. _{The operating principle is that the artificial satellite 10 is first rotated around the ω s} axis tilted at an arbitrary angle α with respect to the light receiving surface of the solar cell 21, and then the maximum and minimum values of the generated power of the solar cell 21 and the minimum value. The direction of the sun is calculated from the average value, and the attitude of the artificial satellite 10 is controlled so that the solar cell 21 faces the direction of the sun based on the finally calculated direction of the sun. By adopting this principle, the attitude of the artificial satellite 10 is controlled in the direction of the sun by using the generated power of the solar cell 21 mounted on the artificial satellite 10 without using the solar sensor 23 and the stellar sensor 22. It becomes possible. Therefore, even if the sun sensor 23 or the star sensor 22 should fail, it is possible to secure the electric power by turning the posture toward the sun, and it is possible to improve the robustness and survivability. Further, even if the artificial satellite 10 has restrictions on the on-board equipment such as a small satellite, it is possible to select not to mount the sun sensor 23 and the star sensor 22 by applying the present embodiment.

*** Other configurations ***
This embodiment can be applied not only to the artificial satellite 10 but also to other types of space structures such as a space station as long as it is a space structure on which the solar cell 21 is mounted.

In the present embodiment, the functions of the acquisition unit 33 and the calculation unit 34 of the sun capture device 31 are realized by software, but as a modification, the functions of the acquisition unit 33 and the calculation unit 34 may be realized by hardware. .. Specifically, the functions of the acquisition unit 33 and the calculation unit 34 are realized by dedicated hardware such as a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, a logic IC, a GA, an FPGA or an ASIC. You may. "IC" is an abbreviation for Integrated Circuit. "GA" is an abbreviation for Gate Array. "FPGA" is an abbreviation for Field-Programmable Gate Array. "ASIC" is an abbreviation for Application Special Integrated Circuit.

As another modification, the functions of the acquisition unit 33 and the calculation unit 34 may be realized by a combination of software and hardware. That is, a part of the functions of the acquisition unit 33 and the calculation unit 34 may be realized by dedicated hardware, and the rest may be realized by software.

10 Artificial satellite, 11 Control system, 12 Controlled plant, 21 Solar cell, 22 Star sensor, 23 Sun sensor, 31 Sun capture device, 32 Sun direction calculator, 33 Acquisition unit, 34 Calculation unit, 41 Controller, 42 Controller, 51 actuators.

Claims (4)

The current generated from the solar cell when the space structure on which the solar cell is mounted rotates about a rotation axis that is inclined at an arbitrary inclination angle with respect to the direction perpendicular to the light receiving surface of the solar cell. An acquisition unit that acquires different current values depending on the rotation angle around the rotation axis,
A calculation unit that calculates the sun direction angle with respect to the rotation axis from the inclination angle and the current value acquired by the acquisition unit.
With
The calculation unit uses the difference and average of the maximum value and the minimum value of the current generated from the solar cell when the space structure rotates about the rotation axis, which is acquired by the acquisition unit. , it calculates the solar direction angle solar capture device. The current generated from the solar cell when the space structure on which the solar cell is mounted rotates about a rotation axis that is inclined at an arbitrary inclination angle with respect to the direction perpendicular to the light receiving surface of the solar cell. An acquisition unit that acquires different current values depending on the rotation angle around the rotation axis,
A calculation unit that calculates the sun direction angle with respect to the rotation axis from the inclination angle and the current value acquired by the acquisition unit.
With
When the rotation angle is 0 °, the current value of the current generated from the solar cell is the maximum value.
The calculation unit is the difference between the current value when the rotation angle is 0 ° and the current value when the rotation angle is 180 °, and the rotation angle is 90 ° or 270, which is acquired by the acquisition unit. ° used, be that solar capture device calculates the solar direction angle a current value when the. The sun trapping device according to claim 1 or 2,
A control system including a controller that controls the posture of the space structure according to the calculation result of the calculation unit. A space structure comprising the control system according to claim 3.

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