JPH06127492A - Unloading device for space navigating object - Google Patents

Abstract

PURPOSE:To perform diversification of a reaction wheel by a method wherein angular velocity data of one of a roll shaft and a yaw shaft is selected by means of angular velocity data around a pitch shaft serving as a starting level to determine a starting momentum, and based on the value thereof, an unloading amount is determined. CONSTITUTION:A space navigating object is provided around the three axes (X-Z-axis) of a machine body with four reaction wheels arranged in a state to be inclined based on a machine body axis. Orientation is controlled such that disturbance around the three axes of the space navigating object is removed by means of an angular movement amount obtained occasioned by rotational drive of the wheels. In this case, angular velocity data around the three axes of the space navigating object is determined by a base body axis converting part 10 to which velocity data of each of the wheels is inputted. From the angular velocity data, an unloading starting level is set, and one of a roll axis (an X-axis) and a yaw axis (a Z-axis) is selected as an practical use axis to set a starting momentum. Based on the staring momentum, an unloading amount around three axes is determined to drive a thruster.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unloading device used for controlling the rotation of a reaction wheel for controlling the attitude of a spacecraft such as an artificial satellite.

[0002]

2. Description of the Related Art Conventionally, a plurality of reaction wheels have been used as attitude control actuators in spacecraft such as artificial satellites. This reaction wheel is tilted with respect to the three axes (roll (x) axis, pitch (y) axis, and yaw (z) axis) of the spacecraft, for example, as shown in FIG. Place 4
Four first to fourth reaction wheels 1 to 4 such as a skew wheel are arranged in a self-sustaining redundant configuration, and
Through the angular momentum (momentum) that accompanies the rotational drive of the fourth reaction wheels 1 to 4, disturbances around the three axes of the spacecraft are removed to control the attitude.

By the way, the first to fourth reaction wheels 1 to 4 as described above have a limit in the number of revolutions thereof, so that the number of revolutions called unloading can be lowered below a specific value during the driving thereof. It is necessary to control and remove its accumulated momentum. Therefore, the spacecraft is provided with an unloading device that controls the rotation speeds of the first to fourth reaction wheels 1 to 4. This unloading device
A well-known gas jet thruster is arranged around the three axes of the fuselage, and this gas jet thruster is unloaded around the three axes of the fuselage (accumulated momentum removal amount) based on the accumulated momentum of the first to fourth reaction wheels 1 to 4. Is driven to generate torque around three axes to remove the accumulated momentum of each of the first to fourth reaction wheels 1 to 4 and control the rotational speed of the reaction wheels 1 to 4.

In such an unloading device, the momentum level set on the axis of the machine is the first.
To the fourth reaction wheels 1 to 4 are not saturated, a shaded area A in FIG. 4 (the other direction is symmetrical with respect to this, but is not shown for convenience of illustration. No.), and the first to fourth reaction wheels 1 to 4 are driven in this area A to remove the accumulated momentum.

As conditions under which the first to fourth reaction wheels 1 to 4 do not saturate, if momentums around the three axes of the body are H _x , H _y and H _z and the wheel storage capacity H _MAX is 6, 3 ^1/2 / 4 (H _x + H _y + H _z ) <6 ^Nms It is expressed by the equation (1). For example, in the (1, 1, 1) direction in FIG. 3, the range is a substantially triangular pyramid shown by B in FIG.

However, in the above unloading device, the usable angular velocity range of the first to fourth reaction wheels 1 to 4 has a relatively wide effective range, which is a substantially triangular pyramidal region B in FIG. However, there is a problem that the operation is very troublesome because it is restricted by using only a very narrow area A among them.

[0007]

As described above, in the conventional unloading device, since it is difficult to effectively use the angular velocity range allowed by the reaction wheel, its operation is very troublesome. Had the problem of being.

The present invention has been made in view of the above circumstances, and the unloading device for a spacecraft is designed so that the angular velocity range of the reaction wheel can be effectively utilized and the operation can be simplified. The purpose is to provide.

[0009]

SUMMARY OF THE INVENTION The present invention relates to an autonomously redundant four reaction wheel for controlling attitude by removing disturbances around the roll axis, pitch axis and yaw axis of a spacecraft. In a spacecraft unloading apparatus for controlling rotation by removing accumulated momentum associated with driving, a gas jet thruster arranged corresponding to three axes of the spacecraft such as a roll axis, a pitch axis and a yaw axis. , The roll axis, the pitch axis, and the yaw axis of the spacecraft from the speed data of the four reaction wheels.
An angular velocity conversion means for obtaining angular velocity data around the axis, and an unloading start level around the pitch axis based on the angular velocity data around the three axes of the spacecraft obtained by the angular velocity conversion means are set, and the roll axis / yaw is set. One of the axes is selected as the execution axis, and the selection means for setting the start momentum, and the rotation of the three axes based on the angular velocity data about the three axes obtained by the angular velocity conversion means based on the start momentum of the execution axis selected by the selection means And an unloading control means for driving the gas jet thruster to remove the accumulated momentum.

[0010]

According to the above construction, the angular velocity data about the pitch axis is used as a start level to select the angular velocity data of one of the roll axis and yaw axis to obtain the start momentum, and the unloading amount is obtained based on this start momentum. This enables effective use of the usable speed range of the first and fourth reaction wheels. Therefore, the use of the first to fourth reaction wheels can be diversified, and the operation can be simplified.

[0011]

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

FIG. 1 shows an unloading device for a spacecraft according to an embodiment of the present invention, in which a body axis conversion unit 10 includes first to fourth reaction wheels 1 to 4 having the self-sustaining redundant structure. Each speed data of 4 (see FIG. 3) is input. A roll axis / yaw axis unloading level determination section 11 is connected to an output end of the machine body axis conversion section 10, and the roll axis / yaw axis unloading determination section 1 is connected.
An unloading controller 12 is connected to the output terminal of 1. Roll axis / yaw axis unloading determination unit 11
Is the unloading start level H _y (start level) of 0.5 ^Nms based on the input speed data around the three axes of the machine and the pitch axis speed data as a base. And, for example, H _y (starting level) = ± ^{13,3 Nms}

As an example, the unloading rule of the roll axis / yaw axis shown in FIG.
Output to 2. Immediately, this unloading rule becomes a substantially triangular region C in the region B shown in FIG. 4, and H _Y = H _y + H _yM (H _yM : margin momentum)

When H _x > H _z , the starting momentum is 13.8 with the roll axis as the execution judgment axis.
^Nms Set to-(HY + H _z ). When H _x <H _z , the execution determination axis is the yaw axis, and the start momentum is 13.8 ^Nms. Set to − (HY + H _x ).

The unloading control unit 12 is connected to the output end of the machine body axis conversion unit 10, and based on the unloading rule from the roll axis / yaw axis unloading level determination unit 12, the angular velocity data of each of the machine body three axes is obtained. A drive signal is generated by obtaining an unloading amount around each axis, and a gas jet thruster (not shown) is driven to remove accumulated moments of the first to fourth reaction wheels 1 to 4.

Further, the wheel driving unit 13 is connected to the output end of the unloading control unit 12. The wheel drive unit 13 receives the drive signal from the unloading control unit 12 and the control torque around the three axes of the machine body, and generates a wheel drive signal based on the drive signal and the control torque to generate the first to fourth drive signals. Reaction wheel 1
4 is driven and controlled. The gas jet thruster (not shown) is arranged corresponding to, for example, the three axes of the spacecraft body.

As described above, the unloading device for the spacecraft is provided with the first to fourth reaction wheels 1
The angular velocity data about the pitch axis is obtained based on the angular velocity data of ~ 4, and the angular velocity data about the pitch axis is used as the unloading start level to select one of the roll axis / yaw axis angular velocity data to generate the start momentum. ,
The unloading control is performed by obtaining the unloading amount around the three axes of the machine based on this start momentum. According to this, it becomes possible to use substantially the entire range as an effective range with respect to the usable speed range of the first and fourth reaction wheels 1 to 4, and thus the first to fourth reaction wheels. The use of 1 to 4 can be diversified, and the operation can be simplified.

In the above embodiment, the case where the first to fourth reaction wheels 1 to 4 are arranged in the 4-skew wheel system has been described, but the present invention is not limited to this.
It can be applied to various arrangement configurations. Therefore, it is needless to say that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

[0019]

As described above in detail, according to the present invention, the speed range of the reaction wheel can be effectively utilized, and the operation of the space navigation vehicle can be simplified. A device can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing an unloading device for a spacecraft according to an embodiment of the present invention.

FIG. 2 is a diagram showing an unloading rule according to FIG.

FIG. 3 is a diagram showing a state in which four reaction wheels are arranged in a self-supporting redundant configuration.

FIG. 4 is a diagram shown for explaining a conventional problem.

[Explanation of symbols]

1 to 4 ... First to fourth reaction wheels, 10 ...
Airframe axis conversion unit, 11 ... Roll axis / Yaw axis unloading level determination unit, 12 ... Unloading control unit, 13
… Wheel drive.

Claims (1)

[Claims] 1. Removal of accumulated momentum associated with driving of four reaction wheels configured autonomously redundantly for removing attitude disturbances around the roll axis, pitch axis and yaw axis of a spacecraft to control attitude. In a unloading device for a spacecraft that controls rotation by means of a gas jet thruster arranged corresponding to three axes of the spacecraft such as a roll axis, a pitch axis, and a yaw axis, and the four reaction wheels. The angular velocity conversion means for obtaining the angular velocity data about the three axes of the spacecraft such as the roll axis, the pitch axis and the yaw axis from each angular velocity data, and the angular velocity data about the three axes of the spacecraft obtained by the angular velocity conversion means. Based on this, set the unloading start level around the pitch axis, select one of the roll axis / yaw axis as the execution axis, and set the start momentum. The gas jet thruster is driven by determining the unloading amount around the three axes based on the angular velocity data around the three axes determined by the angular velocity converting means based on the selection means and the start momentum of the execution axis selected by the selection means, An unloading device for a spacecraft, comprising unloading control means for removing the accumulated momentum.