JPH08178689A - Earth sensor - Google Patents

Abstract

PURPOSE: To avoid the resonance of an earth sensor loaded on an artificial satellite with a mechanical vibrating source such as a posture controlling wheel, impart a function for normally performing a machine body posture error detection to the sensor, and improve the flexibility to satellite operation. CONSTITUTION: This earth sensor has a resonance avoiding computer 20 for transmitting a control signal for avoiding a resonance on the basis of the wheel rotating speed transmitted from a posture controlling computer 19 and the temperature sensor data of a scanning mirror surface part 1 from a temperature control device 8. The presence of the resonance is judged by the resonance avoiding computer 20, and the control signal to the temperature control device 8 is outputted. The temperature of the earth sensor is thus controlled so as to avoid the resonance. Accordingly, the resonance caused by the temperature fluctuation of the earth sensor or the resonance caused when the rotating speed of the posture controlling wheel is changed can be avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth sensor used as a body attitude error detecting sensor in an attitude control system of an artificial satellite.

[0002]

2. Description of the Related Art FIG. 8 shows a structure including a scanning mirror surface portion of a general earth sensor. In FIG. 8, 1 is a scanning mirror surface part, 2 is a mirror surface part driving system, 3 is a condenser lens, 4 is an optical filter, 5 is a detector, 10 is light from the earth, 22 is an amplifier, 23 is a cabinet price detector, Reference numeral 24 represents a digital processor, and 25 represents an attitude error output. 9 is a detailed view of the scanning mirror surface portion 1 of FIG. 8, 11 is a mirror surface, 12 is a mirror surface support rod,
Reference numeral 13 is an external case.

Next, the operation will be described. In FIG. 8, the scanning mirror surface portion 1 scans the surface of the earth at a constant frequency by the mirror surface portion drive system 2. The light 10 from the earth reflected by the mirror surface is collected by the condenser lens 3, only the necessary wavelength light is transmitted by the optical filter 4, and a certain wavelength light is detected by the detector 5, as shown in FIG. Get the output. The output from this detector 5 is amplified by the amplifier 22,
With the cabinet price detector 23, the rising and falling edges are shown in FIG.
It is detected as shown in 0 (c), and the peripheral part of the earth is detected. This is processed by the digital processor 24,
The attitude error is output as shown in FIG. The scanning mirror surface unit 1 for scanning the surface of the earth is composed of a mirror surface 11, a mirror surface supporting rod 12 that supports the mirror surface 11, and an outer case 13 that supports the mirror surface supporting rod 12. The driving torque by the mirror surface drive system 2 causes the mirror surface 11 to vibrate at a constant frequency via the mirror surface support rod 12 to perform scanning.

[0004]

Since the scanning mirror surface portion 1 of the earth sensor vibrates the mirror surface 11 and the mirror support rod 12 at a constant frequency, the mirror support rod 12 resonates due to an external mechanical disturbance vibration. The phenomenon occurs. The cause of the resonance is mechanical vibration due to the rotation of the attitude control wheel mounted on the artificial satellite, and the resonance occurs when the value obtained by converting the rotation speed of the wheel into the vibration frequency coincides with the resonance point of the mirror support rod 12. Occur. Further, it has been known that the resonance point of the mirror-like support rod 12 is changed by the tensile force of the support rod, and its characteristic is shown in FIG. Further, it has been known that the tensile force changes depending on the temperature of the supporting rod, and its characteristics are shown in FIG. The Earth sensor temperature fluctuates daily within a certain temperature range. Therefore, the resonance point also fluctuates day by day within a certain band as shown in FIGS. In the conventional earth sensor, the pulling force of the mirror support rod 12 is adjusted in advance at the test stage on the ground so as to avoid resonance at the wheel rotation speed in the steady satellite operation state. However, the rotational speed of the wheel may be changed during operation in orbit due to a flexible operation request for the artificial satellite according to various situations. In this case, the wheel rotation frequency, which is a mechanical disturbance vibration source, is applied to the resonance band due to the change in the wheel rotation speed, the mirror support rod 12 resonates, the earth surface scanning is not normally performed, and an accurate body attitude error occurs. There was a problem of not being detected.

In the present invention, even when the wheel rotation speed is changed, by changing the tensile force of the mirror support rod, resonance of the earth sensor can be avoided and a function of accurately detecting the attitude error of the body can be provided. Has an aim.

[0006]

The earth sensor according to the present invention has a temperature control device on the scanning mirror surface portion, a heater and a temperature sensor on the scanning mirror surface portion, and controls the mirror surface support rod temperature by a closed loop. The temperature of the mirror support rod changes with the position of the satellite in orbit, so it shows a fixed diurnal variation. For this reason, since the time period in which resonance occurs is almost unchanged, the temperature of the mirror-supporting rod is controlled only by the timer so that the resonance point of the mirror-supporting rod does not coincide with the mechanical vibration frequency of the wheel.

Further, this temperature control device is provided with a device capable of setting the temperature from the ground by a command, and it becomes possible to avoid resonance by monitoring and transmitting a command from the ground. In this case, it has a command decoding device that decodes a command from the ground and controls the temperature control device.

In order for the satellite to autonomously avoid resonance, the rotation speed of the attitude control wheel and the temperature of the scanning mirror surface are monitored, and resonance is avoided when the rotation speed falls within the resonance band. , A resonance avoidance calculator that outputs a signal for changing the temperature setting of the temperature control device for the scanning mirror surface section.

Further, in an earth sensor having two scanning mirror surface portions in which the pulling force of the mirror surface supporting rod of the scanning mirror surface portion is different, the resonance band of each mirror surface supporting rod is deviated, so that one of them is always in resonance. It is possible to output a non-posture error.

[0010]

In the earth sensor according to the present invention, the temperature of the mirror-supporting rod is controlled by the temperature controller by the timer function during the time when resonance may occur. Since the resonance point fluctuates due to the tensile force of the mirror support rod, and the tensile force also fluctuates due to the temperature, the resonance point can be controlled by controlling the temperature. Since the earth sensor temperature and the wheel rotation speed fluctuate daily, the time when resonance occurs is almost constant. The timer function controls the temperature only during a certain period of the day so that the resonance point of the mirror support rod does not match the mechanical vibration frequency due to the wheel rotation.

Further, the present invention monitors the wheel rotation speed on the ground and transmits a command for changing the temperature of the scanning mirror surface portion from the ground when the resonance band of the earth sensor is likely to be applied to the mirror surface supporting rod. Change the temperature of
Avoid resonance. In this case, the temperature setting command from the ground is decoded by the command decoding device and the control signal is output to the temperature control device.

According to the present invention, the rotation speed of the attitude control wheel is monitored by the attitude control computer mounted on the artificial satellite, and the value is used together with the temperature data from the temperature sensor of the scanning mirror surface to make the earth avoidance computer by the resonance avoidance computer. The presence or absence of resonance of the sensor is determined, and a control signal is output to the temperature control device for the scanning mirror surface section. This changes the temperature of the mirror support rod,
Resonance can be avoided.

Further, since the present invention has two scanning mirror surface portions in which the tensile force of the mirror surface supporting rod is different, if the tensile force is set so that the respective resonance bands are separated, either one of the scanning mirror surface portions will be. However, since the resonance band of the other scanning mirror surface portion is apart from the band in which resonance occurs, normal scanning is performed and an accurate attitude error is detected.

[0014]

【Example】

Example 1. FIG. 1 is a diagram showing an embodiment of the present invention,
The earth sensor has a temperature control device having a timer function on the scanning mirror surface. In the figure, 1 is a scanning mirror surface part that scans the surface of the earth at a constant frequency, 2 is a mirror surface part drive system that drives the scanning mirror surface part 1, 3 is a condenser lens that collects the light 10 from the earth reflected by the mirror surface, and 4 is Of the light 10 from the earth, an optical filter 5 that transmits only the necessary wavelength light is a detector that detects a certain wavelength light. A heater 6 and a temperature sensor 7 are attached to the scanning mirror surface portion 1. Reference numeral 8 represents a temperature control device that controls the heater 6 based on the output from the temperature sensor 7, and 9 represents a timer that controls the time during which the temperature control device 8 functions. 2 is a detailed view of the scanning mirror surface portion 1, 11 is a mirror surface for scanning the surface of the earth and reflecting light from the earth, 12 is a mirror surface support rod to which the mirror surface 11 is attached,
Reference numeral 13 denotes an outer case that supports the mirror-finished support rod 12, and the heater 6 and the temperature sensor 7 are attached thereto.

The operation of this embodiment will be described. The scanning mirror surface portion 1 scans the surface of the earth at a constant frequency by the mirror surface driving system 2, and therefore, resonance occurs due to external mechanical disturbance vibration. The resonance point changes due to the pulling force of the mirror support rod 12, and this pulling force also changes according to the temperature of the mirror support rod 12. The temperature of the mirror support rod shows a fixed diurnal variation because it is affected by the position of the satellite in orbit. Therefore, resonance can occur only in a certain time zone of the day, and the timer 9 causes the temperature control device 8 to function during this time zone. The time zone in which resonance can occur depends on the daily fluctuation of the mirror support rod temperature and the wheel rotation speed, but it is several hours when the mirror support rod is hot or cold because the wheel rotation speed is set so that resonance does not occur. The temperature control device 8 controls the heater 6 according to the temperature of the mirror surface supporting rod from the temperature sensor 7 and controls the temperature of the mirror surface supporting rod so that resonance does not occur. In this way, the resonance point of the mirror support rod does not match the mechanical vibration frequency due to the wheel rotation, and resonance is avoided.

Example 2. FIG. 3 is a diagram showing a second embodiment of the present invention, in which a temperature control device 8 is operated by a command from the ground.
It is an earth sensor that has the function of changing the set temperature. In the figure, 14 is a telemetry transmitter mounted on the satellite, 15 is telemetry sent from an artificial satellite, 16 is a ground station for monitoring wheel rotation speed and earth sensor temperature,
17 is a command transmitted from the ground station 16 to the artificial satellite,
Reference numeral 18 denotes a command decoding device which decodes the command 17 and outputs a control signal to the temperature control device 8.

The operation of the second embodiment will be described. The frequency of the mechanical disturbance vibration reaching the earth sensor is the same as the frequency of the wheel rotation speed displayed, and the wheel rotation speed can be monitored to determine the presence or absence of resonance. At ground station 16, wheel rotation speed and earth sensor temperature are monitored by telemetry 15 from telemetry transmitter 14. Command 1 to change the temperature of the mirror support rod 12 when the wheel rotation speed is likely to reach the earth sensor resonance band
Send 7 from the ground to avoid resonance. The resonance frequency, that is, the rotation speed of the wheel that causes resonance, decreases as the temperature of the mirror support rod 12 increases, and increases as the temperature decreases.
The tendency of the change in the wheel rotation speed is judged on the ground, and it is determined whether the temperature of the mirror support rod 12 should be raised or lowered. The temperature setting command 17 from the ground is decoded by the command decoding device 18, and a control signal to the temperature control device 8 is output.

Example 3. FIG. 4 is a diagram showing a third embodiment of the present invention. In this figure, reference numeral 19 designates an attitude control computer mounted on the satellite, in which data relating to the attitude of the satellite is collected. A resonance avoidance calculator 20 sends a control signal to the temperature controller 8 based on the wheel rotation speed sent from the attitude control computer 19 and the temperature sensor data from the temperature controller 8.

The operation of the third embodiment will be described. The sensor output and the like required for attitude control are input to the attitude control computer 19, and among these data, the wheel rotation speed is sent to the resonance avoidance computer 20. Based on the wheel rotation speed data and the scanning mirror surface temperature data from the temperature control device 8, the resonance avoidance computer 20 determines the presence or absence of resonance and outputs a control signal to the temperature control device 8. As a result, the temperature of the scanning mirror surface portion 1 changes, and resonance can be avoided. The presence / absence of resonance is determined by using a table stored in the resonance avoidance computer 20 in which the wheel rotation speed causing resonance and the scanning mirror surface temperature are associated with each other. Since the resonance frequency decreases as the temperature of the mirror support rod 12 increases and increases as the temperature decreases, the resonance avoidance computer 20 determines the tendency of the change in the wheel rotation speed and sends the temperature control device 8 to the mirror support rod 12.
A control signal for raising or lowering the temperature of is transmitted.

Example 4. FIG. 5 is a diagram showing a fourth embodiment of the present invention. As shown in the figure, it is composed of first and second scanning mirror surface portions 1a and 1b. A detailed view of these two scanning mirror surfaces is shown in FIG. 6, in which 11a, 11
b is the first and second mirror surfaces that reflect the light from the earth, 12
a and 12b are first and second supporting mirror surfaces 11a and 11b.
Mirror support rods 13 and 13 are two mirror support rods 12a and 12b.
Is an external case that supports the. The mirror support rod 12a,
12b are constructed with different tensile forces.

The operation of the fourth embodiment will be described. Two
The two scanning mirror surface portions 1a and 1b operate independently of each other, but since the tension forces of the mirror surface supporting rods 12a and 12b are different, the resonance frequency bands are also different as shown in FIG.
In order to make the tensile force of the mirror support rod different, it can be set to an appropriate value because it can be varied within a certain range at the manufacturing / testing stage. Even if resonance occurs at a certain wheel rotation speed, 2
One of the two scanning mirror surface portions 1a and 1b, and the other scanning mirror surface portion 1 operates normally without resonance. Use the data. When the resonance occurs, the amplitude of the output attitude angle data due to noise becomes larger than that of normal data, so that the presence or absence of resonance can be determined by a monitor on the ground. The outputs of the scanning mirror surface units having two systems are both monitored on the ground by telemetry, and one of the outputs of the two systems which is used as the attitude data for attitude control is selected by a command from the ground.

[0022]

Since the earth sensor is constructed as described above in the present invention, the following effects can be obtained.

Resonance is avoided by controlling the temperature of the mirror-supporting rod of the earth sensor by a temperature control device having a timer function only during a period when resonance can occur. Further, the temperature control device functions only during a limited time period of the day, which is efficient.

When the temperature control device can be controlled by a command from the ground, the temperature of the mirror support rod can be changed by a command according to the wheel rotation speed, so that resonance avoidance can be flexibly performed and various Various operational requirements.

A resonance avoidance computer that automatically changes the set temperature of the temperature control device based on the wheel rotation speed data and the mirror support rod temperature data is installed in the satellite to automatically resonate according to the wheel rotation speed. It can be avoided and the burden of operation on the ground is reduced.

By having two scanning mirror surface portions having mirror support rods with different tensile forces, normal data is output from the other even if one causes resonance, so that the influence of resonance can be avoided.

[Brief description of drawings]

FIG. 1 is a diagram of an earth sensor showing a first embodiment of the present invention.

FIG. 2 is a detailed view of the scanning mirror surface portion 1 of the earth sensor having the heater 6 and the temperature sensor 7 according to the first embodiment of the present invention.

FIG. 3 is a diagram of an earth sensor showing a second embodiment of the present invention.

FIG. 4 is a configuration diagram of an earth sensor showing a third embodiment of the present invention.

FIG. 5 is a configuration diagram of an earth sensor showing a fourth embodiment of the present invention.

[Fig. 6] Fig. 6 shows Example 4 of the present invention in which the tensile force is different.
2 is a detailed view of the scanning mirror surface portion 1 of the earth sensor having two mirror support rods 12 and 21. FIG.

FIG. 7 is a diagram showing that the resonance frequency bands are different when the tensile forces are different.

FIG. 8 is a diagram showing a configuration of a conventional earth sensor.

FIG. 9 is a diagram showing details of a scanning mirror surface portion 1 of a conventional earth sensor.

FIG. 10 is a diagram showing output signals at various parts when the earth sensor scans the surface of the earth.

FIG. 11 is a diagram showing the relationship between the tensile force of the earth sensor mirror support rod and the resonance frequency.

FIG. 12 is a diagram showing the relationship between the temperature and the tensile force of the earth sensor mirror support rod.

FIG. 13 is a diagram showing the daily variation of the resonance frequency due to the daily variation of the temperature of the mirror support rod.

[Explanation of symbols]

1 scanning mirror surface part, 2 mirror surface part driving system, 3 condensing lens,
4 optical filter, 5 detector, 6 heater, 7 temperature sensor, 8 temperature control device, 9 timer, 10 light, 1
1 mirror surface, 12 mirror surface supporting rod, 13 outer case, 14
Telemetry transmitter, 15 Telemetry data, 16
Ground station, 17 command, 18 command decoding device,
19 attitude control computer, 20 resonance avoidance device, 21
Mirror support rod, 22 Amplifier, 23 Cabinet value detector, 24
Digital processor, 25 attitude error output.

Claims (4)

[Claims] 1. An earth sensor used for detecting the attitude angle of an artificial satellite, comprising a mirror surface and a mirror surface supporting rod for supporting the mirror surface, the mirror surface at a constant frequency on the earth surface for detecting the peripheral portion of the earth. A scanning mirror surface part for scanning, a driving means for driving the scanning mirror surface part, a heater and a temperature sensor attached to the scanning mirror surface part for adjusting the temperature of the scanning mirror surface part, and the heater by the output from the temperature sensor. A temperature control device for controlling the temperature of the mirror support rod and a timer for presetting a time zone in which resonance of the mirror support rod occurs and operating the temperature control apparatus only in the time zone. Earth sensor. 2. An earth sensor used for detecting the attitude angle of an artificial satellite, comprising a mirror surface and a mirror surface support rod for supporting the mirror surface, said mirror surface at a constant frequency on the surface of the earth for detecting the peripheral portion of the earth. A scanning mirror surface part for scanning, a driving means for driving the scanning mirror surface part, a heater and a temperature sensor attached to the scanning mirror surface part for adjusting the temperature of the scanning mirror surface part, and the heater by the output from the temperature sensor. The temperature control device that controls the temperature and the temperature control data that is installed on the ground and receives the rotation speed data of the satellite attitude control wheel and the satellite attitude control wheel are received through the satellite-mounted telemetry transmission device, and the rotation speed of the wheel changes. And a means for generating a temperature control signal to the temperature control device according to the result of the determination. Earth sensor to collect. 3. An earth sensor used for detecting the attitude angle of an artificial satellite, comprising a mirror surface and a mirror surface support rod for supporting the mirror surface, said mirror surface at a constant frequency on the earth surface for detecting the peripheral portion of the earth. A scanning mirror surface part for scanning, a driving means for driving the scanning mirror surface part, a heater and a temperature sensor attached to the scanning mirror surface part for adjusting the temperature of the scanning mirror surface part, and the heater by the output from the temperature sensor. The temperature control device for controlling the temperature and the presence or absence of resonance of the mirror support rod based on the temperature sensor data and the rotation speed data of the satellite attitude control wheel are used to control the temperature to the temperature control device. An earth sensor having means for outputting a signal. 4. An earth sensor used to detect the attitude angle of a satellite, the earth sensor having a first mirror surface and a first mirror surface support rod for supporting the mirror surface, wherein the first mirror surface detects the peripheral edge of the earth. For the purpose of scanning the earth surface at a constant frequency, a first scanning mirror surface portion, a second mirror surface juxtaposed with the first mirror surface, and a second mirror surface supporting the second mirror surface. And a second mirror surface support rod different from the above
And a second scanning mirror surface portion for scanning the surface of the earth at a constant frequency for detecting the peripheral portion of the earth.