JP3206473B2 - High stability attitude control system for satellite - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an attitude control apparatus for an artificial satellite, and more particularly, to realizing high-accuracy attitude control while suppressing a rapid change in attitude angle error with respect to the influence of driving of onboard equipment and disturbances. High stability attitude control device for artificial satellites.

[0002]

2. Description of the Related Art Generally, an attitude control device for an artificial satellite is configured to control the attitude of the satellite by a single attitude controller, sensor and actuator. Specifically, an attitude controller that obtains an attitude angle error from a difference between a satellite attitude angle detected by an attitude angle sensor and a target attitude angle, and performs a linear operation with respect to each attitude control axis using an attitude angle error signal as an input. The attitude control actuator is driven by the control signal generated by the controller, and is controlled so that the satellite attitude angle becomes a preset target attitude angle.

In such a satellite attitude control device,
The attitude controller is configured to generate a control signal based on the attitude angle error.In order to reduce the attitude angle error and achieve high-accuracy attitude control, the attitude controller must respond to minute input signals. It is necessary to generate a control signal while responding with high sensitivity. However, if the characteristics of the attitude controller are designed in this way, if a large attitude angle error occurs for some reason, a large control signal will be generated from this attitude controller, and a sudden change in the satellite attitude angle will occur. And the saturation of the attitude control actuator output, which not only increases the satellite attitude angular velocity in the control process, but also affects the durability of the attitude control hardware.

In the attitude control of an artificial satellite, in addition to the demand for high-precision control for minimizing the attitude angle error of the satellite as described above and the consideration that the output of the attitude control actuator is limited so as not to generate excessive stress on the satellite, In some cases, it is required to stabilize the attitude by suppressing the satellite attitude angular velocity to a predetermined value or less for stable operation of mission equipment. That is, it is desired to minimize the attitude angle error and stabilize the satellite attitude by making the variation speed of the attitude angle error (satellite attitude angular velocity) equal to or less than a fixed value. Since an actual attitude control actuator that can be mounted on a satellite does not provide sufficient performance in terms of responsiveness, occurrence of a large attitude angle error is inevitable when a large disturbance is suddenly applied. In this case, as long as the attitude control is performed by a single attitude controller that performs a linear operation, the attitude control actuator is driven by a control signal proportional to the attitude angle error to try to converge on the target attitude. As the attitude angle error increases, the satellite attitude angular velocity also increases, resulting in a remote operation from the viewpoint of stabilizing the attitude.

Conventional attitude control devices for artificial satellites include:
As described above, it is common to use a single attitude controller that performs a linear operation. However, JP-A-2-18197 and JP-A-2-77399 disclose an example of performing a nonlinear operation. Is disclosed. In the attitude control device of the above publication, when the output of the attitude sensor exceeds a saturation value set in advance, the attitude angle error signal input to the attitude controller is fixed to a constant value, and a large attitude angle error is generated. Prevent saturation of the attitude control actuator output when it occurs,
Although the effect of quickly reducing the attitude angle error can be expected, the attitude stability is not considered and there is no function to suppress the satellite attitude angular velocity.

Japanese Unexamined Patent Publications Nos. 63-130498 and 64-47699 disclose a structure satellite such as a solar battery paddle attached to an artificial satellite. There is disclosed an apparatus that detects a relative position (angle) with respect to a main body and switches a gain or the like of an attitude controller for satellite attitude control in accordance with the output. FIG.
1 is a block diagram showing the principle of a satellite attitude control apparatus disclosed in Japanese Patent Application Laid-Open No. 64-47699. In FIG. 2, an angle detector 107 is a solar battery paddle 105 that makes one rotation relative to the satellite body while the satellite makes one orbit.
The position (angle) detector, the segment switch 106 is a switch that detects the position of each 90 degrees on each quadrant of the solar battery paddle 105 and switches the switch 108. As the solar battery paddle 105 rotates, the segment switch 1
06, the variable amplifiers 109 and 110 are switched, and the output of the angle detector 107 is used to change the variable amplifiers 109 and 11.
0 and the variable filter 111, and the controller 10
2. To improve control accuracy while ensuring stable operation of a posture control system composed of the actuator 103, dynamics 104 and posture sensor 101. This method resets the gain and frequency characteristics of the attitude control system based on the detected state of the flexible structure, and removes the interference of the resonance frequency of the flexible structure with the attitude control characteristics. Is achieved, but no consideration is given to posture stabilization.

[0007]

As described above, in the attitude control of a satellite, in addition to the demand for high-precision control to reduce the attitude angle error, a sudden change in the attitude angle error is suppressed to stabilize the satellite attitude. It may be required to improve the degree. On the other hand, if an attempt is made to improve the control accuracy with a single attitude controller, when a large attitude angle error occurs, the satellite attitude angular velocity also increases and the stability of the satellite attitude deteriorates. Even if a non-linear operation is introduced as disclosed in JP-A-2-18197 and JP-A-2-77399, control accuracy and attitude stabilization can be achieved as long as a single attitude controller is used. It is difficult to obtain satisfactory performance in both cases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-stability attitude control apparatus for an artificial satellite for realizing high-precision attitude control while suppressing a sudden change in an attitude angle error with respect to the influence of driving of equipment and disturbances. It is to provide.

[0009]

According to a first aspect of the present invention, there is provided an artificial satellite high stability attitude control apparatus based on a satellite attitude angle error signal calculated from a difference between a satellite attitude angle measured by an attitude sensor and a target attitude angle. In a satellite attitude control device for controlling an attitude of an artificial satellite by driving an attitude control actuator, a function of generating an attitude control command signal to be input to the attitude control actuator from the satellite attitude angle error signal is provided.
Comprising, by comparing the different plurality of the posture controller of the control performance, a pre-Symbol satellite attitude angle error signal magnitude and detect and predetermined reference variation rate selects one of said plurality of posture controller A control output signal changeover switch that is connected to the attitude control actuator so as to perform high-precision attitude control while suppressing fluctuations in satellite attitude angular velocity.

A high stability attitude control apparatus for an artificial satellite according to a second aspect of the present invention is the satellite high stability attitude control apparatus for an artificial satellite according to the first aspect, wherein the control output signal switch detects the satellite one sampling cycle before. A velocity calculation function for calculating the fluctuation speed of the attitude angle error from the attitude angle error signal and the satellite attitude angle error signal detected this time, and a predetermined increase boundary value when the magnitude of the satellite attitude angle error signal increases. A first switching function for switching the attitude controller used so far to a one-step control attitude controller having a low performance when it exceeds, and the magnitude of the satellite attitude angle error signal is reduced and set in advance. until a second switching function for switching have the posture controller to the low posture controller of one stage control performance using a satellite attitude angle error signal decreasing direction near when exceeding the reduced time boundary value Until the third switching function for switching have the posture controller to the low posture controller of one stage control performance using a satellite attitude angle error signal when the change rate of the attitude angle error exceeds a preset upper limit value Is in the decreasing direction, and when the variation speed of the attitude angle error falls below the preset lower limit value after the switching by the third switching function is performed, the attitude controller that has been used up to that time is used for the one-step control performance. A fourth switching function for switching to a high attitude controller.

According to a third aspect of the present invention, in the high stability attitude control apparatus for an artificial satellite according to the second aspect, the control output signal switch is replaced with the first switching function. A fifth switching function for switching the attitude controller used so far to an attitude controller having low one-step control performance when an attitude control command signal to the attitude control actuator exceeds a preset saturation limit value; It is characterized by having.

According to a fourth aspect of the present invention, there is provided the high stability attitude control apparatus for an artificial satellite according to any one of the first to third aspects, wherein the attitude is provided on the output side of the control output signal changeover switch. A limiter for limiting the magnitude of the attitude control command signal input to the control actuator is inserted.

According to a fifth aspect of the present invention, there is provided the high stability attitude control apparatus for an artificial satellite according to the first, second or fourth aspect, wherein the control output signal changeover switch and a plurality of attitude controllers are provided. And a limiter for limiting the magnitude of the satellite attitude angle error signal input to the sub-controller to a predetermined value or less.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention.

In FIG. 1, 1 is satellite dynamics,
2 is an attitude control actuator, 3 is a control output signal changeover switch, 4 is an attitude sensor, 5 is an attitude angle error detector, and 6 to 9 are attitude controllers having different circuit configurations and control characteristics, and are mounted on artificial satellites. The satellite attitude angle error signal a generated by the attitude angle error detector 5 based on the satellite attitude angle detected by the attitude sensor 4 such as the earth sensor, and the attitude control command signal b input to the attitude control actuator 2 The control output signal changeover switch 3 selects the attitude controllers 6 to 9 and applies torque to the satellite dynamics 1, thereby performing high-accuracy attitude control while suppressing an increase in the satellite attitude angular velocity.

Here, the attitude controllers 6 to 9 have different control characteristics (control band, gain, operating range, etc.) so as to be able to cope with various situations in consideration of the detection range of the attitude sensor 4.
The attitude controller 6 is a P controller with a simple configuration, and the attitude controller 7 is a PD controller with higher performance by adding differential characteristics to the attitude controller 6, and attitude control. Unit 8 is a low-band PID controller with an additional integration characteristic;
The attitude controller 9 is a high-bandwidth PID controller having higher control performance than the attitude controller 8.

The control output signal changeover switch 3 is connected to a satellite attitude angle error signal a input from the attitude angle error detector 5 at each sampling cycle and the attitude control actuator 2
The attitude control command signal b output to the attitude controller 6 is constantly monitored, and the attitude controller to be selected according to the state is changed from the attitude controller 6 to the attitude controller 9 or vice versa.
Switch to in order. Hereinafter, the configuration and operation of the control output signal changeover switch 3 will be described in detail.

The control output signal changeover switch 3 calculates the fluctuation speed of the attitude angle error from the satellite attitude angle error signal a0 detected one sampling cycle ago and the satellite attitude angle error signal a1 detected this time, and the attitude angle error is calculated. In a case where the attitude controller is in a decreasing direction and its fluctuation speed is lower than a preset lower limit value, the attitude controller used so far is changed to an attitude controller having one-step performance (for example, the attitude controller 6 shifts from the attitude controller 6 to the attitude controller). On the other hand, if the fluctuation speed exceeds the preset upper limit value, the attitude controller used so far is changed to an attitude controller having one-stage lower performance (for example, the attitude controller 8). To the attitude controller 7). In addition, when the attitude control command signal b exceeds a saturation limit value set in advance in consideration of the performance of the attitude control actuator 2, the attitude controller used up to that point has one-step performance. Switch to a lower attitude controller,
The posture control actuator 2 is configured to prevent saturation.

The control output signal change-over switch 3 having the above-described configuration has no disturbance and the satellite attitude angle error signal a is 0.
, The attitude controller 9 having the best control performance
To perform high-precision attitude control. When a large disturbance occurs in this state, the attitude angle error increases despite the optimal control for suppressing the increase in the attitude angle error, and the attitude control command signal b increases accordingly. When the attitude control command signal b increases and exceeds the saturation limit value, the control output signal switch 3 switches the attitude controller 9 to the attitude controller 8 to prevent the attitude control actuator 2 from being saturated, and the performance of the attitude controller 8 The increase in the attitude angle error is suppressed within the range. When the disturbance continues and the attitude angle error further increases and the attitude control command signal b exceeds the saturation limit value, the control output signal changeover switch 3 switches the attitude controller 8 to the attitude controller 7 to switch the attitude control actuator 2. Prevent saturation. If the attitude angle error further increases, the attitude controller 7
To the attitude controller 6 is performed. In this manner, it is possible to avoid saturation of the attitude controller and the attitude control actuator 2 and to cope with a large attitude angle error. Although not shown in FIG. 1, even when the attitude controller 6 is used, in order to prevent saturation of the attitude control actuator 2, the control output signal changeover switch 3 and the attitude control actuator 2 are connected to each other. What is necessary is just to insert a limiter in between.

Next, an operation in the case where a large disturbance is contained and the generated attitude angle error converges to zero will be described. If the disturbance disappears in the state switched to the attitude controller 6, the attitude angle error starts to decrease and the error reduction speed increases, but as the attitude angle error decreases, the driving torque generated by the attitude control actuator 2 also decreases. I do. This is not desirable for quick convergence of the attitude angle error. Therefore,
When the attitude angle error decreases and enters the operation range of the attitude controller 7 having higher gain and higher performance than the attitude controller 6, the control output signal changeover switch 3 detects this and outputs the attitude controller 6 to the attitude controller 6. Switch to 7. As a result, the attitude control command signal b increases, the drive torque of the attitude control actuator 2 is increased, and the convergence of the attitude angle error is accelerated. Similarly, when the attitude angle error further decreases and enters the operation range of the attitude controller 8, the control output signal changeover switch 3 switches from the attitude controller 7 to the attitude controller 8, and further shifts from the attitude controller 8 to the attitude controller. Switch to 9. As a reference value for performing these switchings, a required number of boundary values at the time of reduction is required (three in the case of FIG. 1) in consideration of an operation range and an output size of each attitude controller.
Switching is performed in advance when the attitude angle error decreases and the satellite attitude angle error signal a divides the boundary value at the time of decrease.

In addition to the above switching function, the control output signal changeover switch 3 switches the attitude controller, which has been used up to that point, to the attitude lower in one-step performance when the variation speed of the attitude angle error exceeds a predetermined upper limit value. A function of switching to the controller (for example, switching from the attitude controller 8 to the attitude controller 7) is provided. In this switching, the attitude angle error starts to decrease and is sequentially switched to a high-performance attitude controller,
When the rate of decrease of the attitude angle error increases and exceeds the upper limit, the process is executed regardless of the attitude controller used at that time, thereby suppressing an increase in the satellite attitude angular velocity. When the posture angle error is further reduced in the state where the switching is performed, the decreasing speed is also reduced, and when the predetermined lower limit value is divided, the control output signal change-over switch 3 becomes the posture control used previously. The attitude controller is switched to the original attitude controller having high one-step performance (for example, the attitude controller 7 is switched to the attitude controller 8). By this switching, the attitude angle error converges to 0 more quickly. If the fluctuation speed continues to increase even after switching to the attitude controller with one-step performance, a second upper limit may be set to switch to the attitude controller with one-step performance.

As described above, the high stability attitude control apparatus for an artificial satellite according to the present embodiment includes four attitude controllers 6 to 9 having different control characteristics, and is output from the attitude angle error detector 5. The control output signal changeover switch 3 sequentially switches and uses the attitude controllers 6 to 9 on the basis of the satellite attitude angle error signal a and the attitude control command signal b to the attitude control actuator 2. Does not cause saturation of the attitude control actuator 2 for the range,
Highly accurate attitude control can be realized while restraining the attitude angular velocity to a certain range.

In the above embodiment, the attitude controller is switched by the attitude control command signal to the attitude control actuator when the satellite attitude angle error signal increases due to the disturbance. As in the case of switching when the distance decreases, an increasing boundary value (which may be different from the decreasing boundary value) is set, and when the attitude angle error increases and the satellite attitude angle error signal a exceeds the increasing boundary value, You may make it switch to the attitude controller with low step performance.

In connection with the description of the above-described embodiment, in order to prevent saturation of the attitude control actuator even when a P controller having a simple disturbance and a large disturbance is used,
Although it has been described that the limiter is inserted between the control output signal changeover switch and the attitude control actuator, a limiter for limiting the maximum value of the satellite attitude angle error signal may be inserted into the input of the attitude controller.

Further, the digital output format in which the control output signal changeover switch calculates the variation speed of the attitude angle error from the satellite attitude angle error signal for each sampling period has been described, but the analog format for processing a continuous signal is the same. Configuration is possible. Although the example using four attitude controllers has been described, the number of attitude controllers is not particularly limited.

[0027]

As described above, according to the present invention, high stability attitude control system of the satellite of the present invention includes a plurality of posture controller of different control characteristics, such as can deal with various situations, attitude angle error detector Equipped with a control output signal changeover switch that selects and connects an optimal attitude controller based on the satellite attitude angle error signal detected and its fluctuation speed, and suppresses the satellite attitude angular velocity from becoming excessive in the control process It is configured to be. Therefore, even when the satellite attitude angle suddenly fluctuates greatly due to a large disturbance added from the environment, etc., by performing the satellite attitude control by selecting the most appropriate attitude controller from a plurality of attitude controllers, It is possible to cope with the attitude angle error range, prevent saturation of the attitude control actuator, and achieve high-accuracy attitude control of the satellite while suppressing the attitude angular velocity of the satellite.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of a conventional attitude control device for an artificial satellite.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Satellite dynamics 2 Attitude control actuator 3 Control output signal changeover switch 4,101 Attitude sensor 5 Attitude angle error detector 6-9 Attitude controller 102 Controller 103 Actuator 104 Dynamics 105 Solar cell paddle 106 Segment switch 107 Angle detector 108 switch 109,110 variable amplifier 111 variable filter

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-299499 (JP, A) JP-A-2-185895 (JP, A) JP-A-62-187697 (JP, A) JP-A-2- 18197 (JP, A) JP-A-64-47699 (JP, A) JP-A-63-130498 (JP, A) JP-A-61-102398 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) B64G 1/24 G05D 1/00-1/12

Claims (5)

(57) [Claims] An attitude of a satellite for controlling an attitude of an artificial satellite by driving an attitude control actuator based on a satellite attitude angle error signal calculated from a difference between a satellite attitude angle measured by an attitude sensor and a target attitude angle. in the control device, a function of generating an attitude control command signal to be input to the attitude control actuator from the satellite attitude angle error signal, and a plurality of attitude control device with different control performance, the size of the pre-Symbol satellite attitude angle error signal And a control output signal switch for selecting one of the plurality of attitude controllers and switching to and connecting to the attitude control actuator by comparing the detected attitude and the fluctuation speed with a predetermined reference. A highly stable attitude control apparatus for an artificial satellite, which performs high-accuracy attitude control while suppressing fluctuations. 2. The control output signal changeover switch according to claim 2,
A speed calculation function for calculating the fluctuation speed of the attitude angle error from the satellite attitude angle error signal detected one sampling cycle before and the satellite attitude angle error signal detected this time; When the set increase boundary value is exceeded, the attitude controller that has been used up to that point is moved one step
A first switching function for switching to an attitude controller having a low control performance, and an attitude controller which has been used up to that time when the magnitude of the satellite attitude angle error signal decreases and exceeds a preset decreasing boundary value. A second switching function for switching to an attitude controller having low one-step control performance, and a satellite attitude angle error signal in a decreasing direction, and the attitude angle error fluctuation rate has been used up to a preset upper limit value when it has exceeded a preset upper limit value. And a third switching function for switching the attitude controller to the attitude controller having low one-step control performance, and a satellite attitude angle error signal in a decreasing direction, and the attitude angle error after the switching by the third switching function is performed. Bei a fourth switching function for switching the posture controller used up to a high posture controller of one stage control performance when the variation rate is obtained by dividing a preset lower limit value High stability attitude control device of an artificial satellite according to claim 1, wherein the a. 3. The control output signal change-over switch,
Instead of the first switching function, when the attitude control command signal to the attitude control actuator exceeds a preset saturation limit value, the attitude controller that has been used up to that time has a low level of one-step control performance. The fifth to switch to container
3. The high stability attitude control apparatus for an artificial satellite according to claim 2, further comprising a switching function. 4. A limiter for limiting a magnitude of a posture control command signal input to said posture control actuator is inserted on an output side of said control output signal changeover switch. A high stability attitude control device for an artificial satellite according to the above. 5. A control output signal changeover switch and a limiter for limiting a magnitude of a satellite attitude angle error signal input to a plurality of attitude controllers to a value equal to or less than a preset value. 4. A high stability attitude control device for an artificial satellite according to 1, 2, or 3.