JPS5996100A - Control system of attitude of artificial satellite - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an attitude control system for one artificial satellite.

FIGS. 1 and 2 show an example of a conventional attitude control system for this type of artificial satellite. Here, to simplify the explanation, the roll axis, pitch axis, and yaw axis of the satellite body are respectively referred to as the X axis, y axis, and z axis. In the figure, (1m)
- (1d) are the first wheel, second wheel, third wheel and fourth wheel, (2a) - (2d)
is the first wheel (1a) and the second wheel (1b)
s Third wheel (1C) and fourth wheel (1C)
d) Torque or angular momentum generated in (3a) ~ (
6c) is the torque or angular momentum around the X-axis, y-axis, and two axes, and (4) is the torque or angular momentum of the four wheels (1a) to (1d)
) The torque or angular momentum (2a) to (2d) generated at
is converted into torque or angular momentum (3a) to (3c) about the above-mentioned X-axis, y-axis and two axes.

(5a) to (5C) are control signals that specify the torque or angular momentum around the X-axis, y-axis, and two axes given by a controller etc. from P, and (6) is the control signal that specifies the torque or angular momentum around the three axes. The control signals that define the four wheels (1a
) to (1d) to control signals (7a) to (7d) that define the torque or angular momentum
(7a) to (7d) are four wheels (1a) to (1
(8a) to (8d) are the first wheel drive circuit, the second wheel drive circuit, the third wheel drive circuit, and the fourth wheel drive circuit j (9a) to (9d) are 4
This is the drive signal for each wheel.

Next, the operation or effect will be explained. As shown in FIG. 1, the four wheels (1a) to (1d) are arranged by
The angle formed with the axis is α, the angle formed between the projection of the central axis of the second wheel (1b) onto the X-Z plane and the -X axis is α, and the central axis of the third wheel (1c) is X- Projection onto the g-plane and −
The angle between the projection of the central axis of the fourth wheel (1a) onto the X-Z plane and the X-axis is α, and the angle between the first wheel and the second wheel is α. , the third wheel, and the fourth wheel are each centered at X
It is arranged to have an inclination of γ with respect to the −Z plane. When the four wheels (1a) to (1d) are arranged in this way, the torque or angular momentum (2a) to (2d) generated in the four wheels (1a) to (1d) is y-axis, and torque or angular momentum about the two axes (5
There are physical phenomena observed as a) to (6C). This phenomenon is considered to be a type of transformation, and is represented by a matrix uniquely determined by the arrangement of the four wheels (1a) to (1d).

Let this matrix be matrix C.

In FIG. 2, control signals (5a) to (5C) specifying the torque or angular momentum of the X-axis, y-axis, and
control signals (7a) to (7) that define the torque or angular momentum for the four wheels (1a) to (1d) by
d). The transformation by this arithmetic processing unit (6) is expressed by a matrix that is a pseudo inverse matrix of the matrix C described above. Let this matrix be a matrix.

According to control signals (7a) to (7d) defining torque or angular momentum for the four wheels (1a) to (1d), wheel drive circuits (8a) to (8d) generate drive signals (9a) to (9d) and the wheel (
1a) to (1d) are driven. Driven wheel (1
a) to (1d) include torque or angular momentum (2a) to
(2d) is generated, and this torque or angular momentum (2a)
~(2d) is expressed as the torque or angular momentum around the X axis, the y axis, and the two axes as described above. This is how the conventional attitude control method works.

The attitude of the satellite is controlled by obtaining the desired torque or angular momentum. However, since the conventional attitude control system is configured in one or more ways, if one of the four wheels (1a) to (1d) fails, the thrust generating gas jet device (hereinafter referred to as thruster) While maintaining the satellite's attitude using actuators such as the following, the attitude control must be shifted from attitude control using four wheels to attitude control using three wheels, after temporarily stopping all other normally operating wheels. In some cases, it is necessary to carry extra fuel for thrusters on the satellite.
Additionally, there were drawbacks such as complication in terms of operability in the event of a wheel failure.

This invention was made to eliminate these drawbacks, and even if one wheel fails, the four wheels can be moved while driving the normal wheels without using actuators such as thrusters to maintain the satellite's attitude. The present invention provides a satellite attitude control system that can shift from attitude control using wheels to attitude control using three wheels.

An embodiment of the present invention shown in FIG. 3 will be described below. In Fig. 3, (1a) to (9d) are the same as in Fig. 1 or Fig. 2, and α■ is the four wheels (1a) to (
A second arithmetic processing unit that changes the control signals (7a) to (7d) for the wheels (1d) according to the failure and converts them into actual control signals (11a) to (11a) for the four wheels (1a) to (1d). , (11a) to (lid) are actual control signals for the wheels. However, in FIG. 3, the arithmetic processing device (6) is referred to as a first arithmetic processing device (6).

Next, the operation or effect will be explained.

Assume that one of the four wheels (1a) to (1d) breaks down. here.

For convenience, the failed wheel will be referred to as the first wheel (1a), but the same holds true for other wheels such as the second wheel (1b), the third wheel (1c), or the fourth wheel (1d). . Even though the first wheel (1a) has failed, if control signals (7a) to (7d) continue to be applied to the same wheel as before the failure, the control system will move in an unstable direction. To avoid this,
A second arithmetic processing unit OI is provided to reduce the control signal (7a) for the first wheel to zero within a predetermined time; Third. Control signals (7b) to (7d) for the fourth wheel
) and converts it into an actual control signal for the wheel. This transformation will be represented by a matrix X below. The matrix X is a matrix that satisfies the equation % (11) obtained by calculation with the matrix C above, and is given by the following formula.

Aj+Bj=1 ('j=1.2, 3.4) +
31 Here, each component Aj p Bj of one matrix X has the following value. 4 wheels (1a) to (1d)
When everything is normal, Aj = 1 and Bj = 0 (j = 1.2
, 3.4). If a certain wheel, for example the first wheel (1), fails, change only A1 # B1 while satisfying A1 + B1 = 1, and A1 within a predetermined time.
1=0. Set B1=1. 2nd, 3rd. Fourth
The same applies if the wheels (1b) to (1d) break down.

The wheel (1a) is processed by the second arithmetic processing unit αQ having the function of transformation represented by the matrix X determined in this way.
The control signals (7a) to (7d) for ~(1d) are the actual control signals (11a) for the wheel (Ia) to (1a).
) to (11d), four wheels (
If all of 1a) to (1d) are normal, attitude control is performed exactly the same as the conventional attitude control method.

If a certain wheel, for example the first wheel (1a), breaks down, the attitude control will smoothly shift from attitude control using four wheels (1a) to (1d) to attitude control using three wheels (1b) to (1d). be able to.

However, the second. Third. The same applies if the fourth wheel fails. Since the second arithmetic processing unit aω operates in this way, its effect is that if a certain wheel breaks down, it uses an actuator such as a thruster to maintain its attitude and temporarily restore the other wheels that are operating normally. There is no need to shift from attitude control using four wheels to attitude control using three wheels after stopping.

In addition, although the case of the attitude control system of the satellite which has 4 wheels was demonstrated from 9 above, this invention is not limited to this and may be used for the attitude control system of a satellite which has 5 or more wheels. Furthermore, the present invention can be used not only for wheel failures but also for wheel drive circuit failures.

As described above, in the satellite attitude control system according to the present invention, the second arithmetic processing unit αO having the function of converting represented by two matrices X is provided.

By converting the control signal that defines the torque or angular momentum for the wheels (1a) to (1d), if a certain wheel fails, the normal wheel can be driven without using actuators such as thrusters to maintain the satellite's attitude. 3 from posture control using 4 wheels
This has the advantage of smoothly transitioning to attitude control using two wheels and maintaining the target attitude of the two satellites.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the arrangement of four wheels, FIG. 2 is a block diagram showing a typical example of a conventional attitude control system for an artificial satellite, and FIG. 3 is an example of an embodiment of the present invention. FIG. In the figure, s (1a) to (1a) are the first to fourth wheels. (M) to (2d) j (Q) to (3C) are torque or angular momentum, (4) is a physical phenomenon, and (6) is the first arithmetic processing unit. (8a) to (8d) are first to fourth wheel drive circuits. αe is a second arithmetic processing unit. Note that the same or corresponding parts in the two figures are designated by the same reference numerals. Agent Shin Kuzuno −

Claims (1)

[Claims] In an attitude control system for an artificial satellite using a wheel, a second arithmetic processing device is provided between a first arithmetic processing device that provides a control signal for the wheel and a wheel drive circuit,
An attitude control system for an artificial satellite, characterized in that the second calculation process changes the control signal for the wheel in response to a failure of the wheel or the wheel drive circuit, and converts it into an actual control signal for the wheel.