KR100251006B1 - Position control method of satellite - Google Patents

Abstract

PURPOSE: A method of controlling the attitude of an earth satellite is provided by which a ground control station controls the satellite attitude according to vertical orbit control or orbit control of the satellite even though an electronic device for controlling the satellite attitude included in the satellite loses the control function. CONSTITUTION: In case where attitude processor electronics is in abnormal state so that the orbit or attitude of a satellite becomes unstable, an on-pulse control instruction of a ground control station is received to start delta speed propulsion for a predetermined period of time in order to control the orbit(S410). When the delta speed propulsion is judged to be completed(S420), nutation control is performed if the absolute value of roll error is larger than the critical value of nutation control(S430). A roll attitude control is carried out when the absolute value of roll error is not larger than the critical value or the absolute value of roll error after execution of the nutation breaking is larger than a roll attitude control critical value(S440). A pitch attitude control is performed when the roll error absolute value is not larger than the roll attitude control critical value in the roll attitude control step or a pitch error absolute value after execution of the roll attitude control step is larger than a pitch attitude control critical value(S450). Then, attitude control is carried out(S460).

Description

Posture Control Method of Satellite

The present invention relates to an orbital adjustment and attitude control method of satellites, in particular, if the satellite's own attitude control function is lost or partially lost, the ground control station performs the satellite orbit adjustment by the propulsion of the celestial propulsion. The pulse width and thrust suitable for the trajectory adjustment and attitude control in the order of long braking, roll attitude control, pitch attitude control and yaw attitude control in the case of exceeding the threshold of each error. Controlled by the technique, it is possible to quickly recover the satellite's natural trajectory and posture even if an error occurs in the attitude control electronics of the satellite, and to ensure the continuity of the satellite service, as well as to extend the useful life of the satellite and on the ground. The present invention relates to a technology capable of improving satellite operating capability.

Satellites (hereinafter referred to as 'satellites') can be classified into communication satellites, space observation satellites, earth observation satellites, scientific research satellites, maritime satellites and military satellites according to their purpose. The purpose of this is to be achieved through communication.

Among them, the importance of communication satellites is increasing day by day in recognition that the 21st century will become a highly information and communication society, and many countries are accelerating the development of multimedia technology and the advancement of information and communication infrastructure.

Therefore, multimedia services are expected to become commonplace in the mixed environment such as terrestrial high-speed information communication and satellite high-speed information communication.

To this end, high-speed information and communication networks are diversifying from the initial optical cable center construction plan to wireless and coaxial cables, including satellites. In particular, the unique characteristics of satellites include broadcasting, wide-ranging, and mobility. In order to cope with emergencies such as disasters and provide high-speed application services using sex, we are turning in a mixed form with high-speed satellite communication networks.

Moreover, satellite communication network is somewhat inferior in information transmission ability, but it is advantageous in terms of cost than optical cable and can realize 4Any (Any time Any where, Anyone, Any information) which is the ultimate goal of information communication. The role of satellites is growing rapidly.

As described above, the most important mediator in constructing a satellite communication network is a combination satellite of communication and broadcasting, which is usually equipped with a communication repeater and a broadcast repeater, and FIG. The block diagram shown.

As shown in FIG. 1, the multi-communication satellite system 100 is largely composed of a payload system 110 and a bus system 120.

Here, the payload system 110 is composed of a repeater (111) and an antenna (112), the repeater 111 is composed of one or more transponders (Transponder).

In addition, the bus system 120 includes an attitude and orbit control subsystem 121, a propulsion subsystem 122, a thermal control subsystem 123, and electric power. Electric power supply subsystem 124, telemetry / command & ranging subsystem 125

The roles and operations of each part of the hybrid communication satellite system with these components are as follows.

First, the attitude and trajectory control subsystem 121 of the bus system 120 stabilizes the satellite itself during all missions within the trajectory, drift orbit, initial earth or geostationary orbit.

The propulsion subsystem 122 uses liquid fuel and the like as a system for supplying thrust for maintaining orbit and posture, and uses a plurality of propellers. REA) and four electrothermal hydrazine thrusters (hereinafter referred to as E HT).

Thermal control subsystem 123 is a component that maintains a limit tolerable temperature range for normal operation of each part of the satellite in the space environment.

The power supply subsystem 123 serves to supply power required for the satellite, which is a main power source and is a solar panel in the form of solar panels spreading to the north and south of the satellite, a storage battery for storing energy generated from the solar panel, and a satellite such as the earth or the moon. It is composed of a battery, which is a secondary power source for supplying power when the solar light is not used because it is hidden by the shadow.

In addition, the telemetry / command and ranging subsystem 125 is the part that is involved in the launch of the satellite, the trajectory of the satellite and all the operation of the satellite during its use, and the telemetry of each part within the satellite. It collects the state data and transmits it to the ground control station. Command plays the role of receiving, interpreting, and executing commands from the ground control station to control each part of the satellite, and ranging transitions. In order to track the satellites in orbit and geostationary orbit, it measures the linear distance from the ground control station to the satellites and measures the phase of the signal coming back by transmitting a single frequency (Tone) from the ground to the satellites. To calculate the distance.

Finally, the payload system 110 amplifies and relays a signal sent from the ground.

The configuration and role as described above are related to the composite communication satellite for both communication and broadcasting, but the satellite for other purposes does not deviate significantly from the configuration of FIG. 1 except for the configuration of the payload system 110.

2 is a schematic block diagram showing an example of a satellite control system configuration that plays such a role and role.

As shown, the satellite control system performs the following configuration and operation.

When the telemetry subsystem collects the state data of each part of the satellite 210 and transmits it to the ground control station 230 through the antenna, the ground control station 230 transmits the antenna 220 and the diplexer 231. The received data is received by the receiver 232, the data is converted by the telemetry encoder 233, and applied to the input / output device 234.

Meanwhile, data output from the input / output device 234 and sent to the satellite 210 is data converted by the telecommunication command encoder 238 and through the telecommunication command transmitter 239, the diplexer 231, and the antenna 220. It is transmitted to the satellite 210.

The computer 235 of the ground control station 230 processes the satellite data inputted from the input / output device 234 and the control data inputted from the operating platform 236 through the input / output device 234 and returns the result to the input / output device ( 234 is transmitted to the satellite 210 and output to the display device 237 so that an operator can easily grasp the situation.

The signal transmitted from the ground control station 230 to control each part of the satellite 210 is received and interpreted by the command subsystem through the antenna of the satellite, and then applied to each part of the satellite to control the state of the satellite. do.

On the other hand, satellites must maintain a stable orbit at all times during operation to faithfully perform their roles and to accurately point, and a subsystem for this is a posture or trajectory control system.

3 is a block diagram showing an example of such an attitude / track control subsystem.

As shown, the posture and trajectory control subsystem includes a gyro part 310 composed of a roll gyro and a yogyro, a sensor part 320 composed of a solar sensor, an earth sensor, and a horizontal sensor, and a momentum wheel assembly 340. ), The magnetic talker 350, the command logic processing unit 360 for driving the magnetic talker 350 and the propeller, and the output signals of the gyro unit 310 and the sensor unit 320 and the command subsystem are received as inputs. The momentum wheel assembly 340, the command logic processing unit 360, and an attitude processor electronics (APE) 330 for applying a control signal to the telemetry subsystem.

The attitude and trajectory control system configured in this way adjusts the orbit when the orbit changes due to the effects of the earth's gravity potential, the sun and moon attraction, solar radiation pressure, and the atmosphere of the earth, so that the satellite is always placed in the deadband. The posture control electronics 330 is a system for controlling the satellite in a predetermined posture in order to maintain the correct pointing when the attitude of the satellite becomes unstable as a result of orbital adjustment or when the satellite is launched and enters a final operation trajectory such as a stationary orbit. The magnetic gyro unit 310 or the sensor unit 320 receives the output signal through the momentum wheel assembly 340 or the command logic processing unit 360 to drive the magnetic talker 350 and the propulsion to achieve its purpose. .

In addition, the posture control electronic device 330 transmits data on the posture or trajectory input from the gyro unit 310 or the sensor unit 320 to the ground control station through the telemetry subsystem, and the command data from the ground control station. It is also received through the command subsystem to drive the momentum wheel assembly 340 or the magnetic talker 350 and the propeller to properly control the attitude and orbit of the satellite.

As such, the attitude and orbital control system of the satellite is very important not only for normal satellite operation but also for abnormal state caused by the satellite itself and external factors.

However, among the satellites in operation, the attitude control system functions due to unexpected changes in the space environment, for example, the effects of solar magnetic storms or circuit parts of the momentum wheel and the attitude control electronics. Failure to do so has resulted in serious disruption to satellite mission performance.

In other words, it is not only expensive and time-consuming to recover a satellite once it has returned to its original state or even a part of it, but may also be unusable forever if the posture and orbital control system fails. .

In order to solve the above problems, a method of controlling the momentum wheel assembly or the magnetic talker directly at the ground control station has been developed in case of abnormality in the posture and track control system, but in this case, not only real-time satellite control is possible but also a propeller should be used. There was a problem in that there is no use in controlling the posture or the posture control according to the track adjustment.

The present invention is to solve the conventional problems as described above, even if the electronic device performing the function of the orbital condition and attitude control in the satellite itself loses the control function, the north-south orbit of the satellite that requires the operation of the propeller in the ground control station An object of the present invention is to provide a control method for performing posture control according to adjustment or trajectory adjustment.

1 is a block diagram showing the configuration of a composite communication satellite for both communication and broadcasting.

2 is a schematic block diagram showing an example of the configuration of the satellite control system.

3 is a block diagram showing an example of an attitude and trajectory control subsystem.

4 is a flowchart showing a method for controlling the attitude of satellites according to the present invention.

5 is a schematic view showing an example of a propeller mounting position of a satellite to which the method of the present invention is applied.

6 is a time axis waveform diagram showing pulse execution procedures in the attitude control method of the satellite according to the present invention;

* Explanation of symbols for main parts of the drawings

510: Satellite 520: Reaction Engine Propeller (REA)

530: Electrothermal hydrazine propeller (EHT)

540: solar panel 550: origin motor (AKM)

In the attitude control method of the satellite according to the present invention for achieving the above object, when part or all of the function of the attitude control electronic device of the satellite itself is lost, the ground control station adjusts the orbit of the satellite requiring the operation of the propeller. The posture error occurring during delta speed propulsion and after the completion of the delta speed propulsion is exceeded by the threshold of each error, followed by orbit adjustment and posture in order of braking, roll posture control, pitch posture control and yaw posture control. It is characterized by controlling by applying the pulse width and thrust technique suitable for the control.

In addition, when the attitude of the electronic device is unstable due to an abnormality in the attitude control electronics, the first braking process is performed to compare the absolute value of the roll error with the threshold value of the braking braking. ; The first roll attitude to perform roll attitude control when the absolute value of the roll error in the first braking process is not greater than the threshold value of the long braking or the absolute roll error value after executing the first long braking control is greater than the roll attitude control threshold. Control process; A pitch attitude control that is performed if the absolute roll error value is not greater than the roll attitude control threshold in the first roll attitude control process or if the absolute pitch error value after executing the first roll attitude control process is greater than the pitch attitude control threshold value; Pitch attitude control process; And adjusting the attitude of the satellite, including a yaw posture control process of performing a yaw posture control after the first pitch posture control process is performed or the pitch pitch absolute value is not greater than a pitch posture control threshold in the first pitch posture control process. Characterized in that.

The above objects, features, and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, a preferred embodiment of the attitude control method of the satellite according to the present invention will be described with reference to the "GE3000" series of "Lockheed martin Astro Space Co." applied to KOREASAT with reference to the accompanying drawings. .

The "GE3000" series satellite of "Lockheed Martin Astro Space Co." is a broadcasting and communication complex satellite. The attitude and trajectory control subsystem uses the momentum bias stabilization method to control the attitude by rotating the momentum wheel. It is controlled by the attitude control method.

The configuration consists of a momentum wheel, infrared earth sensor, gyroscope, magnetic talker and propulsion device attitude control electronics.The momentum wheel controls the pitch axis, the magnetic talker controls the roll and yaw axes, It will be used to maintain posture.

4 is a flow chart illustrating a attitude control method of the satellite according to the present invention. First, when an error occurs in the attitude control electronic device and the satellite's trajectory and posture become unstable, it is on to adjust the trajectory of the ground control station that has sensed this. A delta velocity propulsion start process (S410) in which E HT receives a pulse (On-pulse) control command and starts delta velocity propulsion (ΔV burm) pulse thrust for a predetermined time; A delta speed promotion completion determination process (S420) of determining whether delta speed promotion is completed is performed.

A first braking braking process (S430) for executing braking braking if the absolute value of the roll error is greater than the threshold of braking braking when the delta braking propagation is completed as a result of the determination of whether the delta speed propulsion is completed (S420); In the first long braking process (S430), if the absolute value of the roll error is not greater than the threshold of the long braking, or if the absolute absolute roll error value after the first long braking is greater than the roll attitude control threshold, the first roll attitude control is executed. A roll attitude control process (S440); If the absolute roll error value is not greater than the roll attitude control threshold in the first roll attitude control process (S440) or the absolute pitch error value after the first roll attitude control process is greater than the pitch attitude control threshold, the pitch attitude control is executed. A first pitch posture control process (S450); In the first pitch attitude control process S450, the absolute pitch error value is not greater than the pitch attitude control threshold value, or after the first pitch attitude control process is executed, the yaw attitude control process is performed to perform yaw attitude control process S460.

On the other hand, as a result of the determination in the delta speed propulsion completion determination process (S420), if the delta speed initial propulsion operation is not completed, if the absolute value of the roll error is greater than the threshold value of the driving brake, the delta speed driving operation is stopped and the driving brake is stopped. A second braking braking process (S470) to be executed; If the absolute value of the roll error is not greater than the threshold value of the long braking in the second braking process (S470), or the absolute absolute roll error value after the second braking braking is greater than the roll attitude control threshold, the delta speed propulsion operation is stopped and the roll A second roll posture control process (S480) for performing posture control; When the absolute roll error value is not greater than the roll attitude control threshold in the second roll attitude control process (S480) or the absolute pitch error value after executing the second roll attitude control process is greater than the pitch attitude control threshold, the delta speed propulsion operation is stopped. And a second pitch attitude control process (S490) of executing pitch attitude control; If the absolute pitch error value is not greater than the pitch attitude control threshold in the second pitch attitude control process (S490), the delta speed propagation start process (S410) is repeated to resume the stopped delta speed propulsion operation, and the second pitch attitude control is performed. After the process S49 is performed, the process is controlled to repeat the second pitch attitude control process S490.

The reason why the attitude control method of the satellite is performed in the above-described configuration is that if the delta speed propulsion operation is continuously performed by the EHT to adjust the trajectory (S410), a serious roll, yaw error, and driving force are caused by the disturbance torque. In order to minimize this error, the long braking pulses by the REA, and the roll and pitch attitude control pulses must also be fired between the delta speed propulsion pulses (S430 to S450) (S470 to S490).

Here, the delta speed propulsion request time is given as a result of the satellite mission planning, and when the roll error generated due to the delta speed propulsion pulse exceeds the threshold value of the jangdong system, the breeze braking (S430) (S470) before executing the roll error control. Run

If the roll error exceeds the threshold even after executing the braking, roll error control is then executed (S44) (S480). The pitch error is corrected using a propeller as necessary (S450) (S490).

After the delta speed propulsion pulse operation request time for the trajectory adjustment is completed, the yaw angle attitude control is performed using the roll attitude control telemetry data together with the long braking pulse, the roll, and the attitude control pulse (S460).

On the other hand, the operation from the step (S430) to step (S460) can be applied to the attitude control in all cases except for the trajectory adjustment in such a way that the conventional magnetic talker and the momentum wheel can be used instead of the method of controlling the attitude of the satellite. That's the way it is.

5 is a schematic view showing an example of the propeller mounting position of the satellite to which the method of the present invention is applied.

As shown, the propellers of the satellite to which the method of the present invention is applied are provided with four REA 520 at the edges of the east, west, and north sides of the satellite 510 (# 1 to # 12), and EHT 4 The dog is located in the center of the north side of the satellite (510) (# 13 ~ # 16).

Table 1 shows an example of the propeller selection method suitable for each control function in the attitude control method of the satellite by the control command from the ground control station according to the present invention.

TABLE 1

EHT # 13 & 15 (odd) pairs or E HT # 14 & 16 (even) pairs are used for delta velocity propulsion (S410).

In addition, REA # 5 & 7 pairs or REA # 10 & 12 pairs are used to control the long drive due to the exhaust shock during the delta speed propulsion (S430) (S470).

If the roll error continues the driving motion beyond the driving brake threshold, stop the delta speed propulsion and thrust as much as the pulse width calculated from the roll error advantage, and after the half nut period (hereinafter referred to as HNP) again the same pulse width The thrust is selected by the second reverser as the size.

In this case, when the trigger occurs in the positive roll error region, first thrust to REA # 5 or REA # 12 at the maximum vertex, and use the REA # 7 or REA # 10 propeller at the minimum vertex after HNP. First, operate REA # 7 or REA # 10 at the minimum peak, wait for HNP, and use the REA # 5 or REA # 12 propeller at the maximum peak.

The pulse width at this time is determined by the roll error between peak-to-peak, but the thrust technique of 1 second resolution with pulse width of about 1 to 2 seconds is used for long braking.

After the braking operation, a fixed positive or negative roll error occurs. To control the negative roll error, use the east side REA # 7 propeller to control the REA # 5 positive roll error on the east side. (S44) (S480).

Also use REA # 1,2,3,4 on the north side or REA # 10,12 propellers on the west side.

The propeller operation for roll error control is possible at all stages of the roll error, and after the first propeller is activated, a second propeller operation command is sent after the HNP.

For pitch error control, REA # 6, 8, 9, 11 propellers are used (S45) (S490).

In addition, the REA # 1, 2, 3, 4 thrusters on the north side are used for yaw control (S460), REA # 1, 4 pairs for the control of positive yaw error, and REA # 2 for the control of negative yaw error. Three pairs of thrusters are used.

As the ground control propulsion command for the roll, yaw and pitch attitude control of the satellite, a ton width thrust having a resolution of 40 [msec] or a thrust technique of 1 second resolution is used.

As described above, the ground control station calculates the thrust pulse width request time by measuring the copper, roll, and yaw errors for the posture control of the delta speed pulse pulse eye, and then double-pulses the two pulses at HNP time intervals. pulse) The thrust technique is used to perform long braking and roll attitude control, and the single pulse thrust technique using one pulse to perform the pitch attitude control.

Table 2 shows the pulse width requirements of the propeller in the attitude control method of the airborne satellite according to the present invention, and the time axis waveform showing the pulse execution order in the attitude control method of the satellite according to the present invention as shown in FIG. Figure 6 is the same as FIG.

Here, the pulse amplitude of FIG. 6 may be set dark according to various variables such as respective air sizes.

TABLE 2

Pulse width requirement amount of propeller in satellite attitude control method according to the present invention

On the other hand, after the last delta speed propulsion for the north-south trajectory adjustment, the yaw angle control pulse is executed together with the pulses for the braking, roll and pitch top control.

There is no satellite telemetry data for the yaw angle, but in an environment without propeller operation, the yaw posture data is obtained by exchanging the posture data between the roll and the yaw by gyroscopic coupling due to the orbital rotation of the satellite. The value can be predicted.

When the roll control is completed and the roll angle is around 0 [°], posture change occurs between the roll and the yaw, and the rate of change of the roll angle instantaneously represents the yaw angle.

The yaw angle prediction value Ψ is −229 (dψ / dt), where dψ / dt means the measured roll variation [° / min].

Calculate the pulse width corresponding to the predicted yaw error according to the propulsion pulse width requirement calculation formula for the yaw attitude control in Table 2, and select the corresponding REA thruster pair as shown in Table 1 to thrust the pulses, and then again after the HNP time interval Yaw control is performed using a double-pulse thrust technique that operates REA pairs with pulses.

In the above embodiments, although the communication satellite has been described as an example of an artificial satellite to which the method of the present invention is applied, the same applies to satellites having different uses such as space observation satellites, earth observation satellites, scientific research satellites, maritime satellites, and military satellites. Needless to say, it applies.

As described in detail above, according to the attitude control method of the satellite according to the present invention, when an error occurs in the attitude control electronic device of the satellite, the on-pulse mode attitude control method for performing orbital adjustment and attitude control that requires the operation of the propeller is provided. In this case, even if an error occurs in the satellite attitude control electronics, the attitude of the satellite control station can be quickly restored to ensure the continuity of the satellite service, and to extend the service life of the satellite. It has the effect of providing satellite operation capability.

As such, preferred embodiments of the present invention are disclosed for purposes of illustration, and those skilled in the art will be able to make various modifications, changes, additions, and the like within the spirit and scope of the present invention. Such modifications and the like fall within the scope of the following claims. Should be seen.

Claims (5)

In the event of an abnormality in the attitude control electronics and the satellite's trajectory and posture, the delta speed starts for a certain period of time due to the on-pulse control command of the ground control station for the trajectory adjustment. Propulsion pulse thrust initiation process; Determining whether or not the completion of the delta speed propulsion is completed; When the delta speed propulsion is completed, when the absolute speed of the error is greater than a threshold value of the braking braking, a first braking braking process for executing a long braking braking; rolls in the first braking braking process; A first roll posture control process for executing roll posture control if the absolute value of the error is not greater than the threshold value of the long braking or the absolute roll error value after executing the first long braking control is greater than the roll attitude control threshold value; The first pitch attitude control process that executes pitch attitude control if the absolute absolute roll error value is not greater than the roll attitude control threshold value or the pitch error absolute value after executing the first roll attitude control process is greater than the pitch attitude control threshold value. ; And a yaw attitude control process of performing a yaw attitude control after the first pitch attitude control process is not greater than a pitch attitude control threshold value or the first pitch attitude control process is performed in the first pitch attitude control process. A attitude control method of a satellite, characterized in that the attitude of the satellite is adjusted by controlling the propeller in the electronic control device. The method of claim 1, wherein the determination result in the process of determining whether the delta speed propulsion completion; When the delta speed propulsion operation is not completed, if the absolute value of the roll error is greater than the threshold value of the braking braking, stopping the delta speed propulsion and performing the braking braking process; If the absolute value of the roll error in the second braking process is not greater than the threshold value of the long braking brake, or the absolute value of the roll error after executing the second braking braking is greater than the roll attitude control threshold, the delta speed propulsion operation is stopped and the roll attitude control is performed. A second roll attitude control process of executing; If the absolute roll error value is not greater than the roll attitude control threshold in the second roll attitude control process or the absolute pitch error value after executing the second roll attitude control process is greater than the feedback attitude control threshold, the delta speed propulsion operation is stopped and the pitch A second pitch attitude control process of performing attitude control; And if the absolute pitch error value is not greater than the pitch attitude control threshold in the second pitch attitude control process, repeating the delta speed propulsion starting process of claim 1 to resume the stopped delta speed propulsion operation, and performing the second pitch attitude control. And after performing the process, repeating the second pitch attitude control process to control the attitude control method of the satellite. The attitude control method of claim 1 or 2, wherein the brake braking process, the roll attitude control process, and the yaw attitude control process are controlled by thrust of two pulses at a half-cycle time interval by the reaction engine propeller. . The method of claim 1 or 2, wherein the pitch attitude control process; Attitude control method of a satellite, characterized in that the thrust is controlled by one time by the reaction engine propeller. A first long braking process of performing a long braking braking operation when the absolute value of the roll error is large when the absolute value of the roll error is compared with the absolute value of the roll error when the satellite is unstable due to an abnormality in the attitude control electronic device; The first roll attitude to perform roll attitude control when the absolute value of the roll error in the first braking process is not greater than the threshold value of the long braking or the absolute roll error value after executing the first long braking control is greater than the roll attitude control threshold. Control process; A pitch attitude control that is performed if the absolute roll error value is not greater than the roll attitude control threshold value in the first roll attitude control process or if the absolute pitch error value after executing the first roll attitude control process is greater than the pitch attitude control threshold value; Pitch attitude control process; And a yaw posture control process of performing yaw posture control after the first pitch posture control process is not greater than a pitch posture control threshold in the first pitch posture control process or after executing the first pitch posture control process. The attitude control method of the satellite, characterized in that for adjusting the attitude of the satellite.

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