JP2002145199A - Attitude control device for space vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance accuracy in attitude stability and prolong life. SOLUTION: First to fourth driving wheels 12-15 are rotatably mounted on a space vehicle 10, and the first to fourth driving wheels 12-15 are driven and controlled in a sated that the number of revolutions is offset and so that the summation of angular momentum is kept in the vicinity of 0, to control the attitude of the space vehicle 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spacecraft deployed in orbit around the earth such as an earth observation satellite,
In particular, it relates to the attitude control device.

[0002]

2. Description of the Related Art Generally, as a posture control device for controlling the posture of a spacecraft, four drive wheels called, for example, reaction wheels, which can be rotationally driven, are provided with a well-known four skew (SKEW) with respect to the body coordinate system. A zero-momentum system is known in which the drive wheels are arranged and selectively driven to rotate so that the total sum of the momentum of the spacecraft 10 is controlled to be close to zero to control the attitude.

[0003] In such an attitude control device, for example, as shown in FIG.
When the orbit goes around, the disturbance angular momentum accumulated in the drive wheel rotates with respect to the body coordinate system on the orbital plane, so that the angular momentum absorbed by the drive wheel has a periodic component.

That is, when the spacecraft 10 makes one orbit in the orbit, its accumulated angular momentum vector is fixed to the inertial system according to the law of conservation of angular momentum, so that the X-axis component and the Z-axis component of the airframe are changed. It changes periodically. In particular,
For example, the X-axis component of the accumulated momentum is the orbital position A
Has a positive value at 0, 0 at the orbital positions B and D, and a negative value at the orbital position C. (See FIG. 6 (a).) However, in the above attitude control device, while the spacecraft 10 makes one orbit of the orbit, the wheel rotation speed of the drive wheel increases as shown in FIG. In order to pass through zero twice (the rotation direction is reversed) of D, when the zero crosses, the friction torque of the drive wheel reaches the value of the static friction torque and rapidly changes as shown in FIG. ,
The sudden change causes a large disturbance to the attitude of the spacecraft 10, which makes it difficult to promote the attitude stability.

[0005] Further, according to this, the frequency of using the drive wheel in a low rotation range is increased in consideration of the occurrence of disturbance affecting the attitude of the spacecraft 10, and the life of the drive wheel is shortened. There is a problem that.

[0006] The problem of the attitude stability is one of the important issues in realizing various observation operations that have been studied in the field of recent space development.

[0007]

As described above, the conventional attitude control apparatus for a spacecraft has a problem that it is difficult to achieve high accuracy of attitude stability and its life is short. Have.

An attitude control device for a spacecraft which has a simple configuration and can promote a high degree of accuracy of attitude stability. The present invention has been made in view of the above circumstances, and has a simple configuration and an attitude control apparatus. Accuracy of stability can be promoted, and
It is an object of the present invention to provide an attitude control device for a spacecraft capable of promoting a longer life.

[0009]

SUMMARY OF THE INVENTION According to the present invention, there is provided a rotationally drivable motor for controlling the attitude of a spacecraft by controlling the angular momentum.
Space navigation comprising: at least one drive wheel; and wheel drive control means for controlling the drive wheels such that each of the drive wheels is given a rotational speed offset and the sum of the angular momentums is kept close to zero. This constitutes a body posture control device.

According to the above configuration, even when the body component of the airframe changes due to one round of the orbit of the spacecraft, the sum of the angular momentum can be controlled to be close to 0 without performing the inversion drive control of the drive wheel. Accordingly, the posture can be controlled in a state where the change in the friction torque is avoided. Therefore, it is possible to control the angular momentum by making full use of the performance of the drive wheel, and it is possible to improve the attitude stability and extend the life of the drive wheel.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an attitude control device for a spacecraft according to an embodiment of the present invention. First to fourth drive wheels 12 to 15 include a redundant system, for example, as shown in FIG. 3 axes (X axis, Y axis, Z axis) of spacecraft 10 shown in
And a known skew arrangement so as to be rotatable. These first to fourth drive wheels 12 to 1
5 are connected to driving units 16 to 19, respectively, and the input terminals of the driving units 16 to 19 are connected to an attitude control unit 20.

The attitude control unit 20 is connected to, for example, an attitude detection sensor 21, and receives input of attitude information about the three axes of the spacecraft 10 detected by the attitude detection sensor 21.
The attitude control unit 20 calculates a drive control signal for each of the drive units 16 to 19 based on the input attitude information and outputs the signal to each of the drive units 16 to 19 as described later.

The driving units 16 to 19 generate driving signals based on the input driving control signals, and rotate the first to fourth driving wheels 12 to 15 in a predetermined direction so that the sum of the angular momentum is 0. The attitude of the spacecraft 10 around the three axes is controlled by controlling the spacecraft 10 to be in the vicinity.

That is, for each of the first to fourth drive wheels 12 to 15, the attitude control unit 20 performs, for example, a rotational speed offset corresponding to an angular momentum larger than the amplitude of the periodic component of the body coordinate system as shown in FIG. Is used as a reference position to generate each drive control signal such that the vector sum of angular momentums of the first to fourth drive wheels 12 to 15 is close to 0, and to each of the drive units 16 to 19 Output.

Then, based on the drive control signal, the drive units 16, 18 rotate the first and third drive wheels 12, 14 in one direction corresponding to the offset setting vector, as shown in FIG. To generate a forward direction vector for each rotation axis. At the same time, the driving units 17 and 19 control the second and fourth driving wheels 13 and
15 is rotated in the other direction opposite to the offset setting vector to generate a forward direction vector for each rotation axis.

Here, the first to fourth drive wheels 12
Nos. 15 to 15 no longer cause the friction torque to pass through zero as shown in FIG. 4 with the rotation drive, and without a sudden change in the friction torque,
It is kept stable. Accordingly, when the first to fourth drive wheels 12 to 15 are driven to rotate via the drive units 16 to 19, the vector sum of the angular momentums of the respective wheels is maintained while maintaining a stable friction torque. It is set near zero, and controls the attitude of the spacecraft 10 around the three axes.

As a result, the first to fourth drive wheels 1
At the time of driving from 2 to 15, disturbance to the spacecraft 10 due to a sudden change in friction torque is prevented, and stable attitude control is realized.

As described above, the attitude control device for the spacecraft has the first to fourth drive wheels 12 to 15 mounted on the spacecraft 10 so as to be rotatable, and the first to fourth drive wheels are provided. The wheels 12 to 15 are driven so that the rotation speeds are offset and the sum of the angular momentums is kept close to 0, so that the attitude of the spacecraft 10 is controlled.

According to this, even when the body component of the aircraft changes with one orbit of the spacecraft 10, the first
In addition, since the sum of the angular momentums can be controlled to be close to 0 without inverting the fourth drive wheels 12 to 15, the attitude can be controlled in a state in which a sudden change in the friction torque is avoided.

As a result, the first to fourth drive wheels 1
The angular momentum can be controlled by making full use of the performances of 2 to 15, and the posture stability can be easily improved and the life thereof can be extended.

In the above embodiment, the first to fourth embodiments
Of four drive wheels 12 to 15 are arranged in a skewed manner and mounted on the spacecraft 10. However, the present invention is not limited to this. For example, four or more drive wheels including a redundant system may be used. It is also possible to apply to an attitude control system using.

Further, in the above-described embodiment, a case has been described where the present invention is applied to the system for controlling the attitude of the spacecraft 0 flying in orbit around the earth. However, the present invention is not limited to this, and other astronomical objects may be used. The present invention is also applicable to attitude control of a spacecraft flying in an orbit, and substantially the same effect is expected.

Therefore, the present invention is not limited to the above-described embodiment, but can be variously modified in the implementation stage without departing from the scope of the invention. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements.

For example, even if some components are deleted from all the components shown in the embodiment, the problems described in the section of the problem to be solved by the invention can be solved, and the effects described in the effects of the invention can be solved. Is obtained, a configuration from which this configuration requirement is deleted can be extracted as an invention.

[0026]

As described above in detail, according to the present invention, the space is simplified in structure, and the accuracy of posture stability can be promoted and the life of the space can be promoted. An attitude control device for a navigation body can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an arrangement configuration of a spacecraft attitude control device according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram shown for explaining a concept of setting a rotational speed offset with a total sum of angular momentums of first to fourth drive wheels in FIG. 1 being 0.

FIG. 3 is a conceptual diagram showing a concept of a rotational speed offset for setting a vector sum of first to fourth drive wheels of FIG. 1 to zero.

FIG. 4 is a characteristic diagram showing a relationship between a rotational speed offset and a friction torque in FIG. 2;

FIG. 5 is a conceptual diagram showing the relationship between the body coordinate system of a spacecraft orbiting an orbiting earth orbit and the accumulated angular momentum to which the present invention is applied.

FIG. 6 is a characteristic diagram shown to explain a problem of the conventional attitude control device.

FIG. 7 is a characteristic diagram showing a change in friction torque generated when the drive wheel of FIG. 6 passes a rotation speed of zero.

[Explanation of symbols]

 10 ... Spacecraft. 11 ... the earth. 12 First drive wheel. 13 Second drive wheel. 14 Third drive wheel. 15 Fourth drive wheel. 16: Drive unit. 17 ... drive unit. 18 ... drive unit. 19 ... drive unit. 20 ... posture control unit. 21 ... posture detection sensor.

Claims (2)

[Claims] 1. Four or more rotationally drivable drive wheels for controlling the attitude by controlling the angular momentum of a spacecraft, and each of the drive wheels is provided with a rotational speed offset and each angular momentum is controlled. And a wheel drive control means for controlling the drive so that the sum of the distances is kept close to zero. 2. The attitude control device for a spacecraft according to claim 1, wherein the four or more drive wheels are arranged in a skew including a redundant system, and each is driven to rotate in a fixed direction.