JPH02128999A - Attitude/orbit control device of artificial satellite - Google Patents

Abstract

PURPOSE:To provide effective controllability for an orbit by controlling the jetting timing of each reaction jet, which is provided for controlling the attitude, and the width of jetting time so that the sum of impulses applied round the center of gravity of an artificial satellite concerned will become zero. CONSTITUTION:In case orbit control in a spin plane is made using two reaction jets 7, 8, the reaction jet with greater torque shall perform jetting with a pulse width T as expressed by T=kT, k=min(FA.LA.FB.LB)/MAX(FA.LA.FB.LB), where T is pulse width of that of the jets 7, 8 which has smaller torque, FA, FB are thrust forces of the jets 7, 8, and LA, LB are torque arm. The min (FA.LA.FB.LB) and MAX(FA.LA.FB.LB) represent the smaller and larger ones of torques FA.LA.FB.LB.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an attitude and orbit control device for a spin-stabilized artificial satellite.

[Conventional technology]

The following method has been used to control the orbit of a spin satellite within the spin plane (a plane perpendicular to the spin axis).

FIG. 3 is a perspective view showing an example of the arrangement of a sun sensor and a reaction jet in a conventional system, and FIG. 4 is an operation timing diagram of the conventional system shown in FIG. In FIG. 3, a sun sensor 10 generates a sun pulse when the sun enters its field of view.

The phase of the sun pulse output from the sun sensor 10 is measured, and when the desired rotational phase is reached, the radial reaction jet 11 of the satellite is pulse-injected. The rotational phase from the sun pulse to the injection can be uniquely determined from the desired orbit control direction, the solar direction, and the spin axis direction. In order to reduce attitude fluctuations during orbit control, the off-modulation method described below is used to arrange the reaction jets so that the thrust vector of the reaction jets 11 passes through the center of gravity of the satellite. Off-modulation refers to arranging two reaction jets 7.8 to sandwich the satellite center of gravity 9 as shown in Figure 2, and by injecting both jets simultaneously as shown in Figure 4, the torque around the center of gravity is reduced. Minimize. Figure 2 is a diagram of a typical artificial satellite viewed from a perspective perpendicular to the spin axis.

If the attitude changes due to residual torque caused by a difference in thrust between the two reaction jets, one of the reaction jets is turned off at an appropriate time to cancel the change. Furthermore, a method is also used in which the attitude of the satellite is changed to make the satellite spin axis parallel to the desired orbit control direction, and the orbit is controlled by a reaction jet installed parallel to the spin axis of the satellite.

[Problem to be solved by the invention]

In the above-described conventional method of arranging reaction jets so that their thrust vectors pass through the satellite's center of gravity, large restrictions are imposed on the position of attaching the reaction jets, which is not preferable from the standpoint of satellite design. Another drawback is that it cannot respond to changes in the center of gravity caused by fuel consumption or the like. In the off-modulation method, when one reaction jet is turned off, a large torque is applied to the satellite, resulting in a large nutation.

This nutation greatly disturbs the sensor output, so the only sensor that can be used to determine the injection phase is a sun sensor that outputs stable pulses even under large attitude changes; star sensors and earth sensors with narrow fields of view have limited output. It can't be used because it's so disturbed. Furthermore, there is a drawback that if the off-modulation period matches the satellite's nutrition frequency, the nutrition may diverge. Furthermore, the system using a reaction jet parallel to the spin axis has the disadvantage that it is necessary to change the attitude of the satellite to the desired orbit control direction, which imposes significant restrictions on satellite operation.

[Means to solve the problem]

The attitude and orbit control device for an artificial satellite according to the present invention includes a sensor for detecting the attitude of an artificial satellite, a reaction jet system for controlling the attitude, and a reaction jet system having a predetermined phase and injection time width based on a signal from the sensor. In a spin-stabilized artificial satellite comprising a control circuit for driving a jet, the control circuit controls the injection timing and injection time width of the reaction jet so that the sum of impulses applied to the mouth of the center of gravity of the artificial satellite becomes zero. It is characterized by keeping the satellite attitude constant during orbit control.

〔Example〕

Next, the present invention will be explained with reference to FIGS. 1 and 2.

FIG. 1 is a block diagram showing an embodiment of an apparatus for controlling the attitude and orbit of an artificial satellite according to the present invention. This embodiment includes a sensor 1, phase setting counters 21 and 22 that start counting by the output pulse of this sensor, and phase setting counters 21 and 2.
A pulse width setting counter 31.32 starts counting at the same time as the count-up of step 2, and a reaction jet selection circuit 41.4 selects a reaction jet to be injected.
2, and a reaction jet drive circuit 51.2 for injecting a reaction jet from the time when the pulse width setting counter 21.22 starts counting until it counts up.
~54 and reaction jet 61. 64, and two identical circuits are provided from the phase setting counter to the reaction jet. Phase setting counter 21, 2
2. Pulse width counters 31, 32. The reaction jet selection circuits 41 and 42 receive data (count values) from commands from the ground or from a computer on board the satellite.

(reaction jet selection) setting is possible.

When performing trajectory control in the spin plane, two reaction jets 7 and 8 shown in FIG. 2 are used. FA the thrust of reaction jet 7.

Let the torque arm be LA+, the thrust of the reaction jet 8, and the torque arms be Fa and LB, respectively.

9 is the satellite center of gravity position. reaction jet 7,8
Among the torques FA-LA and FB-Ln, the larger one is written as MAX (FA-LA, FaL8), and the smaller one is written as min (FA・LA, Fa・La). When injecting the reaction jet 7.8 with a smaller torque with a pulse width T, the reaction jet with a larger torque has a pulse width T given by the following formula.
’ to inject. The pulse width T is determined in consideration of the amount of orbit control, the efficiency of orbit control, the time allowed for orbit control, the characteristics of the reaction jet, etc.

T' = kT Thereby, the impulses obtained by the reaction jet 7.8 are both T-min (FA-La.

Fa-Ls), and the change in satellite attitude becomes extremely small. The phase setting counters 21, 22 . Pulse width counter 31, 3
2. Data is set in the reaction jet selection circuits 41 and 42.

In addition, when calculating equation (1), the reactor jet thrust is used. Regarding the value of the torque arm, data before the launch of the artificial satellite may be used, or values experienced after the launch may be used. Furthermore, it is also possible to determine the attitude using a sensor mounted on the artificial satellite, calculate k in equation (1) from changes in this attitude, and automatically set the phase setting counter, pulse width counter, and reaction jet selection circuit.

〔Effect of the invention〕

As explained above, according to the satellite attitude and orbit control device of the present invention, it is possible to minimize attitude fluctuations during orbit control due to mismatch between the thrust of the reaction jet and the torque arm, and to perform efficient orbit control. . Furthermore, since the attitude variation is small, there is an effect that sensors whose data is likely to be disturbed by attitude variation (for example, a star sensor, an earth sensor) can be used as a reference for reaction jet injection.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the satellite attitude and orbit control device of the present invention, Fig. 2 is a view of a general artificial satellite as seen from a perspective perpendicular to the spin axis, and Fig. 3 is a block diagram showing an embodiment of the satellite attitude and orbit control device of the present invention. FIG. 4 is a perspective view showing an example of the arrangement of a sun sensor and a reaction jet in the method, and FIG. 4 is an operation timing diagram of the conventional method shown in FIG. 1...Sensor, 21.22...Phase setting counter,
31.32... Pulse width setting counter, 41.42.
...Reaction jet selection circuit, 51. ~54...
・Reaction jet drive circuit, 61. ~64.
7.8... Reaction jet, 9... Satellite center of gravity position, 10... Sun sensor, 11... Radial direction reaction jet.

Claims (1)

[Claims] A spin stable type comprising a sensor for detecting the attitude of an artificial satellite, a reaction jet system for controlling the attitude, and a control circuit that drives the reaction jet with a predetermined phase and injection time width based on a signal from the sensor. In the artificial satellite, the control circuit maintains the attitude of the artificial satellite during orbit control by controlling the injection timing and injection duration of the reaction jet so that the sum of impulses applied around the center of gravity of the artificial satellite becomes 0. An artificial satellite attitude and orbit control device characterized by: