Thruster control method for guaranteeing attitude stability and orbit control efficiency

Abstract

A thruster control method for guaranteeing attitude stability and orbit control efficiency includes the steps that in each control period of a computer, attitude control jet required to be output by each thruster is calculated according to the current angle and angular velocity of a satellite, and orbit control jet required to be output is calculated according to the number of orbits required to be adjusted; then, respectively selecting the thrusters which need to be subjected to attitude control output and orbit control output at the current rhythm, and setting an attitude and orbit multiplexing mark; then an orbit control thruster combination containing the thruster with the attitude and orbit multiplexing mark is selected, and marks of'two times of air injection in one beat 'are set for all the thrusters in the combination; and carrying out two-time air injection pulse width output on the thruster with the mark of'two-time air injection is needed in one beat 'according to conditions.

Description

Technical Field

[0001] The invention relates to a thruster control method for ensuring attitude stability and orbit control efficiency, and belongs to the field of satellite attitude control and orbit control. Background Art

[0002] With the rapid development of the aerospace industry, satellite missions on orbit are becoming more and more complex, the need for orbit adjustment is becoming stronger, the payload is increasing, the power consumption is increasing, the solar array area is increasing, the flexibility of satellites is becoming more and more obvious, and satellite control technology is constantly improving. In addition, in order to reduce costs and reduce the weight of satellites, thrusters are generally not configured separately for attitude and orbit. Basically, there will be a situation where thrusters are occupied during attitude control and orbit control at the same time. In order to meet the stability of attitude control, the shortest orbit control time, and the highest guidance accuracy, the use of thrusters is an optimization space that can be explored at this stage.

[0003] In the past, satellite flexibility was relatively small, and on-board delays had little effect on satellite platform stability. Now, the flexibility frequency of many satellites has been as low as the designed controller bandwidth, and the frequency is very dense. The on-board delay link is an important factor in the critical stability of the system or the excitation of flexibility. Therefore, when using thruster control, there are very strict real-time requirements for the jet pulse width of the attitude control output. Summary of the invention

[0004] The technical problem solved by the present invention is: in view of the problem in the current prior art that the traditional thruster control has insufficient real-time control over the jet pulse width output for attitude control and the accuracy gradually cannot meet the requirements, a thruster control method is proposed to ensure attitude stability and orbit control efficiency.

[0005] The present invention solves the above technical problems by the following technical solutions:

[0006] A thruster control method for ensuring attitude stability and orbit control efficiency, comprising:

[0007] Preset the attitude control jet and orbit control jet of each thruster in the current control cycle;

[0008] Select the thrusters that simultaneously perform attitude control jet output and orbit control jet output in the current beat, and perform attitude and orbit reuse identification;

[0009] According to the satellite orbit adjustment direction of the thruster with attitude and orbit reuse identification, each thruster in the current adjustment direction is grouped by secondary identification;

[0010] Double jet output control is performed on the thrusters grouped by the secondary identification.

[0011] The preset methods for attitude control jet and orbit control jet of each thruster are:

[0012] The satellite angle and satellite angular velocity of the satellite at the current moment are collected in real time by measuring sensors;

[0013] According to the satellite three-axis control torque, determine the pre-set attitude control thrusters corresponding to the three axes of the satellite respectively;

[0014] Convert the satellite's three-axis control torque into the jet pulse width of the corresponding attitude control thruster;

[0015] According to the adjustment amount required for the satellite attitude control mission, the speed increment required for the satellite in the corresponding direction is determined, the pre-installed orbit control thrusters corresponding to the three axes of the satellite are determined, and the jet pulse width of the orbit control thrusters in each direction is calculated.

[0016] The method of selecting the thruster that performs attitude control output and orbit control output at the current beat is:

[0017] Two 1×n dimensional matrices are established, namely the attitude control jet usage state matrix A and the orbital jet usage state matrix B. When any thruster in the matrix needs to be ejected, the corresponding position in the matrix is ​​assigned a value of 1, and if it is not used, it is assigned a value of 0;

[0018] Perform AND operations on the attitude control jet usage state matrix A and the orbit jet usage state matrix B to obtain the thrusters occupied by both attitude control and orbit control, and mark the determined thrusters with attitude and orbit reuse marks.

[0019] In the attitude control jet usage state matrix A, n is the number of thrusters, which is established according to the jet pulse width of the attitude control thruster corresponding to the axis obtained by calculation; in the orbital jet usage state matrix B, n is the number of thrusters, which is established according to the jet pulse width that the orbital control of each thruster should output obtained by calculation.

[0020] According to the satellite orbit adjustment direction of the thruster with attitude and orbit reuse mark, each thruster in the current adjustment direction is selected as the thruster that needs to perform two orbit control jets in any beat within the current control cycle. After the screening is completed, a secondary mark is set for all thrusters that meet the conditions, and the secondary mark means that two jets are required in one beat.

[0021] The control method for double jet output of grouped thrusters is:

[0022] Send two jet output instructions to the thrusters marked with two jet outputs in one beat respectively, and select the thrusters that need to output jets for attitude control and orbit control in any beat. The first output instruction is the attitude control pulse width time, and the second output instruction is the orbit control pulse width time;

[0023] For the remaining thrusters that require two jets to set the mark within one beat, the first output command is 0, and the second output command is the orbit control pulse width time.

[0024] In any beat, except for one thruster that needs to perform attitude control output jet and orbit control output jet respectively, the remaining thrusters, regardless of whether they have been marked or not, perform jet output control once per beat.

[0025] The orbit control thrusters are arranged in pairs and installed relative to the satellite's center of mass. The jet direction of the orbit control thrusters is set to achieve three-axis six-directional jetting based on the satellite's body coordinate system. When selecting a thruster that needs to perform two control outputs in any beat, it is determined that the thruster is participating in the derivation and adjustment of any direction of the satellite to select the thruster corresponding to the mark that requires two jets in one beat.

[0026] When any thruster beat requires attitude control output jet and orbit control output jet respectively, the attitude control jet pulse width shall be given priority.

[0027] The thruster is made to output two pulse widths in one beat to reduce on-board delay and ensure the stability of satellite attitude control.

[0028] The advantages of the present invention compared with the prior art are:

[0029] (1) The present invention provides a thruster control method for ensuring attitude stability and orbit control efficiency. By setting "attitude and orbit reuse" and "two jets required within one cycle" identification groups and performing different real-time double jet pulse width control outputs, the attitude control jet can be output in time, the on-board attitude control delay can be reduced, and the stability of the satellite platform can be ensured. At the same time, the orbit control jet can be effectively output, which saves orbit control time and improves orbit control accuracy.

[0030] (2) When the present invention uses the jet to perform attitude and orbit control simultaneously, in order not to excite the module of the flexible attachment and ensure timely output of attitude control, when the thruster has both an attitude control jet pulse width and an orbit jet pulse width, attitude control is prioritized and sub-beat orbit control is not performed by default. This achieves timely output of attitude jets by the large flexible satellite under the control of the thrusters, avoids instability of the large flexible satellite control system caused by delays, and the design of outputting jets twice within one control cycle enables rapid output of the orbit control jet. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A flow chart of the thruster control method provided for the invention; DETAILED DESCRIPTION

[0032] A thruster control method for ensuring attitude stability and orbit control efficiency, in each control cycle of the computer, firstly, according to the current angle and angular velocity of the satellite, the attitude control jet required to be output by each thruster is calculated, and according to the number of orbital elements to be adjusted, the orbit control jet required to be output is calculated; then, the thrusters that need to perform both attitude control output and orbit control output in the current beat are selected, and the "attitude and orbit reuse" mark is set; then, the orbit control thruster combination including the thruster with the "attitude and orbit reuse" mark is selected, and the "two jets are required in one beat" mark is set for all thrusters in the combination; and the thrusters with the "two jets are required in one beat" mark are output with two jet pulse widths according to different situations.

[0033] The thruster control method to ensure attitude stability and orbit control efficiency, such as Figure 1 As shown, the specific steps include:

[0034] Preset the attitude control jet and orbit control jet of each thruster in the current control cycle;

[0035] Select the thrusters that simultaneously perform attitude control jet output and orbit control jet output in the current beat, and perform attitude and orbit reuse identification;

[0036] According to the satellite orbit adjustment direction of the thruster with attitude and orbit reuse identification, each thruster in the current adjustment direction is grouped by secondary identification;

[0037] Double jet output control is performed on the thrusters grouped by the secondary identification.

[0038] The preset methods for attitude control jet and orbit control jet of each thruster are:

[0039] The satellite angle and satellite angular velocity of the satellite at the current moment are collected in real time by measuring sensors;

[0040] According to the satellite three-axis control torque, determine the pre-set attitude control thrusters corresponding to the three axes of the satellite respectively;

[0041] Convert the satellite's three-axis control torque into the jet pulse width of the corresponding attitude control thruster;

[0042] According to the adjustment amount required for the satellite attitude control mission, the speed increment required for the satellite in the corresponding direction is determined, the pre-installed orbit control thrusters corresponding to the three axes of the satellite are determined, and the jet pulse width of the orbit control thrusters in each direction is calculated.

[0043] The method of selecting the thruster that performs attitude control output and orbit control output at the current beat is:

[0044] Two 1×n dimensional matrices are established, namely the attitude control jet usage state matrix A and the orbital jet usage state matrix B. When any thruster in the matrix needs to be ejected, the corresponding position in the matrix is ​​assigned a value of 1, and if it is not used, it is assigned a value of 0;

[0045] Perform AND operations on the attitude control jet usage state matrix A and the orbit jet usage state matrix B to obtain the thrusters occupied by both attitude control and orbit control, and mark the determined thrusters with attitude and orbit reuse marks.

[0046] In the attitude control jet usage state matrix A, n is the number of thrusters, and the jet pulse width of the attitude control thruster corresponding to the axis is established according to the calculated value; in the orbital jet usage state matrix B, n is the number of thrusters, and the jet pulse width that should be output by the orbital control of each thruster is established according to the calculated value.

[0047] According to the satellite orbit adjustment direction of the thruster with attitude and orbit reuse mark, each thruster in the current adjustment direction is selected as the thruster that needs to perform two orbit control jets in any beat within the current control cycle. After the screening is completed, a secondary mark is set for all thrusters that meet the conditions, and the secondary mark means that two jets are required in one beat.

[0048] The control method for double jet output of grouped thrusters is:

[0049] Send two jet output instructions to the thrusters marked with two jet outputs in one beat respectively, and select the thrusters that need to output jets for attitude control and orbit control in any beat. The first output instruction is the attitude control pulse width time, and the second output instruction is the orbit control pulse width time;

[0050] For the remaining thrusters that require two jets to set the mark within one beat, the first output command is 0, and the second output command is the orbit control pulse width time.

[0051] In any beat, except for one thruster that needs to perform attitude control output jet and orbit control output jet respectively, the remaining thrusters, regardless of whether they have been marked or not, perform jet output control once per beat.

[0052] The orbit control thrusters are arranged in pairs and installed relative to the satellite's center of mass. The jet direction of the orbit control thrusters is set to achieve three-axis six-directional jetting based on the satellite's body coordinate system. When selecting a thruster that requires two control outputs in any beat, the thruster is judged to be participating in the derivation and adjustment in any direction of the satellite to select the corresponding thruster marked as requiring two jets in one beat.

[0053] When any thruster beat requires attitude control output jet and orbit control output jet respectively, the attitude control jet pulse width shall be given priority.

[0054] The thruster is made to output two pulse widths in one beat to reduce on-board delay and ensure the stability of satellite attitude control.

[0055] The following is further described in conjunction with the accompanying drawings and preferred embodiments of the specification:

[0056] In the current embodiment, in the thruster control method for ensuring attitude control stability while improving orbit control efficiency:

[0057] 1) Assign attitude control jet and orbit control jet to each thruster in the current control cycle

[0058] The satellite angle and angular velocity can be obtained in real time through the measurement sensor. According to the controller designed for the three axes of the satellite, the control torque required to be output by the three axes can be calculated. According to the pre-installed attitude control thruster usage combination on the satellite, the corresponding thruster is selected for each axis of the satellite, and the control torque is converted into the jet pulse width (i.e., the jet time of each time) of the corresponding thruster.

[0059] The required adjustment amount of the satellite's orbital elements is converted into the speed increment that needs to be changed in the corresponding direction of the satellite. According to the pre-installed orbit control thruster usage combination on the satellite, the total time required for the corresponding thrusters to jet in each direction is calculated.

[0060] 2) Pick out the nozzles that are occupied by both the attitude control jet and the orbit control jet

[0061] Two 1×n dimensional matrices A / B are established, where n is the number of thrusters. A is defined as the attitude control jet usage state matrix, and B is defined as the orbital jet usage state matrix. If the thruster is used, the corresponding position element is assigned a value of 1, and if it is not used, the corresponding position element is assigned a value of 0.

[0062] The current beat obtains the theoretically calculated jet pulse width that the attitude control should output on each thruster, and the state of the A matrix can be established; at the same time, the theoretically calculated jet pulse width that the orbit control should output on each thruster is also obtained, and the state of the B matrix can also be established.

[0063] By performing an "AND" operation on matrices A and B, we can obtain the thrusters occupied by both attitude control and orbit control. These thrusters are marked and the "attitude and orbit reuse" flag is set.

[0064] 3) Select a thruster that requires two jets per beat

[0065] The thruster combination used for orbit control needs to fire simultaneously to minimize the interference torque on the satellite, otherwise the satellite attitude will overshoot or even diverge. Therefore, the orbit control combination where the thrusters reused by attitude control are located must be selected, and all thrusters in this combination must be marked with "two jets are required in one beat".

[0066] 4) Implement double jet output for special thruster group

[0067] For the thrusters that display the "two jets required in one beat" mark, two jets are output. For the thrusters that multiplex attitude and orbit, the first output command is the attitude control pulse width time, and the second output command is the orbit control pulse width time. For other thrusters in the combination, the first output command is 0, and the second output command is the orbit control pulse width time.

[0068] When the current beat thruster is occupied by both the attitude control jet and the orbit control jet, the thruster combination for orbit control is output twice in one beat. The first beat sends the attitude control pulse width command to the reused thruster, and the second beat sends the orbit control pulse width command to the remaining thrusters in the combination. This way of sending commands enables the attitude control pulse width to be output in a timely manner, ensuring the stability of satellite attitude control; at the same time, it saves the output time of orbit control and improves the guidance efficiency and guidance accuracy.

[0069] Example:

[0070] A satellite is equipped with 24 thrusters, 12 main thrusters, numbered a1 to a12, and 12 backup thrusters, numbered b1 to b12. The thrusters for the positive attitude control of the satellite roll axis are numbered a5 / b5, and the thrusters for the negative attitude control of the roll axis are numbered a6 / b6; the thrusters for the positive attitude control of the pitch axis are numbered a7 / b7, and the thrusters for the negative attitude control of the pitch axis are numbered a8 / b8; the thrusters for the positive attitude control of the yaw axis are numbered a9 / b9, and the thrusters for the negative attitude control of the yaw axis are numbered a10 / b10.

[0071] The thrusters for satellite orbit control in the +X direction are numbered a1 / b1 / a2 / b2, and those for -X direction are numbered a3 / b3 / a4 / b4; the thrusters for +Y direction orbit control are numbered a5 / b5 / a6 / b6, and those for -Y direction orbit control are numbered a7 / b7 / a8 / b8; the thrusters for +Z direction orbit control are numbered a9 / b9 / a10 / b10, and those for -Z direction orbit control are numbered a11 / b11 / a12 / b12.

[0072] Table 1 Attitude control thruster usage combination table

[0073] Satellite control axis The thrusters used Positive roll axis a5 / b5 Negative roll axis a6 / b6 Positive pitch axis a7 / b7 Negative pitch axis a8 / b8 Positive yaw axis a9 / b9 Negative yaw axis a10 / b10

[0074] Table 2 Orbital control thruster usage combination table

[0075]

[0076]

[0077] (1) Assign attitude control jets and orbit control jets to each thruster in the current control cycle.

[0078] If the satellite is adjusting its orbital altitude and orbital eccentricity, orbital control is required in the +X and +Z directions. Assuming that the +X direction requires jetting for 300 seconds and the +Z direction requires jetting for 200 seconds, the current beat requires thrusters a1 / b1 / a2 / b2 and a9 / b9 / a10 / b10 to work.

[0079] The current satellite three-axis attitude is controlled by jet. According to the received satellite attitude and angular velocity, the controller solves and assumes that the attitude control requires the positive roll axis, negative pitch axis, and positive yaw axis to provide control torque. The current beat requires thrusters a5 / b5 to output a jet pulse width of 50 milliseconds, a8 / b8 to output a jet pulse width of 80 milliseconds, and a9 / b9 to output a jet pulse width of 100 milliseconds.

[0080] (2) Select the nozzles that are occupied by both the attitude control jet and the orbit control jet

[0081] Establish the attitude control jet usage state matrix A, and assign values ​​to the matrix A according to the current usage of the attitude control thruster.

[0082] A=[0 0 0 0 1 0 0 1 1 0 0 0 0 0 0 0 1 0 0 1 1 0 0 0];

[0083] Establish the attitude control jet usage state matrix B, and assign values ​​to the matrix B according to the current usage of the orbit control thruster.

[0084] B=[1 1 0 0 0 0 0 0 1 1 0 0 1 1 0 0 0 0 0 0 1 1 0 0];

[0085] A and B=[0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0]

[0086] From the results, it can be seen that the thrusters occupied by both attitude control and orbit control are numbered a9 / b9, and the "attitude and orbit reuse" flag is set for a9 / b9.

[0087] (3) Select a thruster that requires two jet outputs per beat

[0088] The thrusters required for orbit adjustment in the +Z direction of the satellite are a9 / b9 / a10 / b10. They work in pairs at the same time, otherwise they will generate interference torque on the satellite, thus affecting the satellite attitude.

[0089] The thrusters numbered a9 / b9 are involved in the orbit adjustment of the satellite in the +Z direction. The thrusters participating in the orbit control in the +Z direction include a10 / b10. Therefore, the four thrusters numbered a9 / b9 / a10 / b10 are all marked with the "two jets required in one beat" sign.

[0090] (4) Implementing double jet output for special thruster groups

[0091] If the control cycle of the satellite is 0.5 seconds, the attitude control pulse width is generally small. In order to reduce system delay and ensure the stability of large flexible satellites, the attitude control jet needs to be output in time. The orbital jet is generally longer. If the orbital control thruster is not occupied, the jet pulse width of the control cycle is output in each beat until the required jet duration is completed.

[0092] The thrusters currently performing orbit control are a1 / b1 / a2 / b2 and a9 / b9 / a10 / b10, which adjust the orbit height in the +X direction and the orbit eccentricity in the +Z direction respectively. The current beat of thrusters a1 / b1 / a2 / b2 is not occupied by the attitude control thrusters, so a1 / b1 / a2 / b2 performs one jet per beat, and the jet duration is 0.5 seconds. Thrusters a9 / b9 / a10 / b10 have been set to the "two jets in one cycle" flag. Thrusters a9 / b9 are occupied by attitude control and orbit control at the same time. Therefore, the first attitude control pulse width sent to the four thrusters is (0.1 seconds; 0 seconds; 0.1 seconds; 0 seconds), and the second attitude control pulse width sent to the four thrusters is (0.4 seconds; 0.4 seconds; 0.4 seconds; 0.4 seconds). Other attitude control thrusters are not occupied at the same time, so they only need to execute one jet in one cycle. The jet pulse width executed by thrusters a5 / b5 is (0.06 seconds; 0.06 seconds), and the jet pulse width executed by thrusters a8 / b8 is (0.08 seconds; 0.08 seconds).

[0093] It can be clearly seen from the thruster pulse width distribution above that the jet pulse width calculated by the attitude control is output in real time, and the jet pulse width output time of the orbit control only wastes the time of the attitude jet pulse width output.

[0094] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0095] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A thruster control method for ensuring attitude stability and orbit control efficiency, characterized in that include: Preset the attitude control jet and orbit control jet of each thruster in the current control cycle; Select the thrusters that simultaneously perform attitude control jet output and orbit control jet output in the current beat, and perform attitude and orbit reuse identification; According to the satellite orbit adjustment direction of the thruster with attitude and orbit reuse identification, each thruster in the current adjustment direction is grouped by secondary identification; Double jet output control is performed on the thrusters grouped by the secondary identification.

2. A thruster control method for ensuring attitude stability and orbit control efficiency according to claim 1, characterized in that: The preset methods for attitude control jet and orbit control jet of each thruster are: The satellite angle and satellite angular velocity of the satellite at the current moment are collected in real time by measuring sensors; Calculate the satellite three-axis control torque according to the satellite angle and the satellite angular velocity, and determine the pre-set attitude control thrusters corresponding to the three axes of the satellite according to the satellite three-axis control torque; Convert the satellite's three-axis control torque into the jet pulse width of the attitude control thruster corresponding to each axis; According to the adjustment amount required for the satellite attitude control mission, the speed increment required for the satellite in the corresponding direction is determined, the pre-installed orbit control thrusters corresponding to the three axes of the satellite are determined, and the jet pulse width of the orbit control thrusters in each direction is calculated.

3. A thruster control method for ensuring attitude stability and orbit control efficiency according to claim 1, characterized in that: The method of selecting the thruster that performs attitude control output and orbit control output at the current beat is: Two 1×n dimensional matrices are established, namely the attitude control jet usage state matrix A and the orbital jet usage state matrix B. When any thruster in the matrix needs to be ejected, the corresponding position in the matrix is ​​assigned a value of 1, and if it is not used, it is assigned a value of 0; Perform AND operations on the attitude control jet usage state matrix A and the orbit jet usage state matrix B to obtain the thrusters occupied by both attitude control and orbit control, and mark the determined thrusters with attitude and orbit reuse marks.

4. A thruster control method for ensuring attitude stability and orbit control efficiency according to claim 3, characterized in that: In the attitude control jet usage state matrix A, n is the number of thrusters, which is established according to the jet pulse width of the attitude control thruster corresponding to the axis obtained by calculation; in the orbital jet usage state matrix B, n is the number of thrusters, which is established according to the jet pulse width that the orbital control of each thruster should output obtained by calculation.

5. A thruster control method for ensuring attitude stability and orbit control efficiency according to claim 1, characterized in that: According to the satellite orbit adjustment direction of the thruster with attitude and orbit reuse mark, each thruster in the current adjustment direction is selected as the thruster that needs to perform two orbit control jets in any beat within the current control cycle. After the screening is completed, a secondary mark is set for all thrusters that meet the conditions, and the secondary mark means that two jets are required in one beat.

6. A thruster control method for ensuring attitude stability and orbit control efficiency according to claim 1, characterized in that: The control method for double jet output of grouped thrusters is: Send two jet output instructions to the thrusters marked with two jet outputs in one beat respectively, and select the thrusters that need to output jets for attitude control and orbit control in any beat. The first output instruction is the attitude control pulse width time, and the second output instruction is the orbit control pulse width time; For the remaining thrusters that require two jets to set the mark within one beat, the first output command is 0, and the second output command is the orbit control pulse width time.

7. A thruster control method for ensuring attitude stability and orbit control efficiency according to claim 6, characterized in that: In any beat, except for one thruster that needs to perform attitude control output jet and orbit control output jet respectively, the remaining thrusters, regardless of whether they have been marked or not, perform jet output control once per beat.

8. A thruster control method for ensuring attitude stability and orbit control efficiency according to claim 1, characterized in that: The orbit control thrusters are arranged in pairs and installed relative to the satellite's center of mass. The jet direction of the orbit control thrusters is set to achieve three-axis six-directional jetting based on the satellite's body coordinate system. When selecting a thruster that needs to perform two control outputs in any beat, it is determined that the thruster is participating in the derivation and adjustment of any direction of the satellite to select the thruster corresponding to the mark that requires two jets in one beat.

9. A thruster control method for ensuring attitude stability and orbit control efficiency according to claim 8, characterized in that: When any thruster beat requires attitude control output jet and orbit control output jet respectively, the attitude control jet pulse width shall be given priority.

10. A thruster control method for ensuring attitude stability and orbit control efficiency according to claim 8, characterized in that: The thruster is made to output two pulse widths in one beat to reduce on-board delay and ensure the stability of satellite attitude control.

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