A thruster control method to ensure attitude stability and orbit control efficiency

Abstract

A kind of thruster control method for ensuring attitude stability and orbit control efficiency, in each control cycle of computer, first, according to the current angle and angular velocity of satellite, the attitude control jet required to be output by each thruster is calculated, and the orbit control jet required to be output is calculated according to the orbit root number to be adjusted;Then, the thruster that needs to be output for attitude control and also needs to be output for orbit control at the current beat is selected respectively, and the "attitude and orbit reuse" flag is set;Then, the orbit control thruster combination containing the thruster with the set "attitude and orbit reuse" flag is selected, and the "two times of jet in one beat" flag is set for all thrusters in the combination;The thruster with the "two times of jet in one beat" flag is output twice according to the pulse width.

Description

Technical Field

[0001] This invention relates to a thruster control method that ensures attitude stability and orbit control efficiency, belonging to the field of satellite attitude control and orbit control. Background Technology

[0002] With the rapid development of the aerospace industry, satellite missions in orbit are becoming increasingly complex, the need for orbit adjustments is growing stronger, payloads are increasing, power consumption is rising, solar array areas are expanding, satellite flexibility is becoming more pronounced, and satellite control technology is constantly evolving. Furthermore, to reduce costs and satellite weight, thrusters are generally not configured separately for attitude and orbit control; they are typically occupied simultaneously during both. To ensure stable attitude control while minimizing orbit control time and maximizing guidance accuracy, thruster utilization represents a significant area for optimization at this stage.

[0003] In the past, satellites had relatively low flexibility, and on-board delays had little impact on the stability of the satellite platform. Now, many satellites have flexible frequencies as low as the designed controller bandwidth, and the frequencies are very dense. On-board delays are an important factor in the critical stability of the system or inducing 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 this invention is that, in the current technology, the real-time control of jet pulse width for attitude control output by traditional thruster control is insufficient and the accuracy is gradually failing to meet the requirements. Therefore, a thruster control method that ensures attitude stability and trajectory control efficiency is proposed.

[0005] The present invention solves the above-mentioned technical problem through the following technical solution:

[0006] A thruster control method for ensuring attitude stability and trajectory control efficiency includes:

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

[0008] Select the thruster that performs both attitude control jet output and trajectory control jet output at the current beat, and mark it as an attitude and trajectory reuse device.

[0009] Based on the satellite orbit adjustment direction of the thrusters with attitude and orbit reuse identifiers, the thrusters in the current adjustment direction are re-identified and grouped.

[0010] The thruster after secondary identification and grouping is subject to dual jet output control.

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

[0012] The satellite's current angle and angular velocity are collected in real time by measuring sensors.

[0013] Based on the satellite's three-axis control torque, determine the pre-set attitude control thrusters corresponding to the satellite's three axes;

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

[0015] Based on the adjustment required for the satellite attitude control mission, determine the required velocity increment of the satellite in the corresponding direction, determine the pre-set orbit control thrusters corresponding to the three axes of the satellite, and calculate the jet pulse width of the orbit control thrusters in each direction.

[0016] The method for selecting a thruster that simultaneously outputs attitude control and trajectory control at the current beat is as follows:

[0017] Establish two 1×n dimensional matrices, 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 jet, 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 an AND operation on the attitude control jet usage state matrix A and the orbital jet usage state matrix B to obtain the thrusters that are simultaneously occupied by attitude control and orbital control, and mark the determined thrusters with attitude and orbital reuse flags.

[0019] In the attitude control jet usage state matrix A, n is the number of thrusters, established based on the calculated jet pulse width of the attitude control thruster corresponding to the axis; in the orbital jet usage state matrix B, n is the number of thrusters, established based on the calculated jet pulse width that each thruster should output for orbital control.

[0020] Based on the satellite orbit adjustment direction of the thrusters with attitude and orbit reuse indicators, select the thrusters that need to perform two orbit control jets in any cycle within the current control period. After screening, set a secondary indicator for all thrusters that meet the conditions. The secondary indicator indicates that two jets are required in one cycle.

[0021] The method for controlling the dual jet output of the grouped thrusters is as follows:

[0022] Two jet output commands are sent to the thrusters that need to release the jet mark twice within a single cycle. Select any thruster that needs to perform attitude control jet output and trajectory control jet output separately in any cycle. The first output command is the attitude control pulse width time, and the second output command is the trajectory control pulse width time.

[0023] For the other thrusters that require two jet ejection marks within one cycle, the first output command is 0, and the second output command is the orbital control pulse width time.

[0024] Within any given cycle, except for the thrusters that require separate attitude control and trajectory control jet outputs in one cycle, all other thrusters, regardless of whether they have been marked, perform jet output control once per cycle.

[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 coordinate system. When selecting a thruster that needs to perform two control outputs within any cycle, the thruster is selected based on whether it is participating in the satellite's directional adjustment. The thruster that needs to perform two jets within one cycle is identified as the one that needs to perform two jets within one cycle.

[0026] When the thruster needs to output jet for attitude control and jet for trajectory control at any time, the attitude control jet pulse width shall be given priority.

[0027] The thruster is output with two pulse widths per cycle to reduce on-board delay and ensure satellite attitude control stability.

[0028] The advantages of this invention compared to the prior art are:

[0029] (1) The thruster control method provided by the present invention ensures attitude stability and orbit control efficiency. By setting "attitude and orbit reuse" and "two jets required in one cycle" flag groups and performing different real-time double jet pulse width control outputs, the attitude control jet can be output in a timely manner, reducing the on-board attitude control delay and ensuring the stability of the satellite platform. At the same time, the orbit control jet can be output effectively, saving orbit control time and improving orbit control accuracy.

[0030] (2) When using jet propulsion for attitude and orbit control, in order to avoid exciting the mode of the flexible appendage and ensure timely output of attitude control, the present invention prioritizes attitude control when the thruster has both attitude control jet pulse width and orbit jet pulse width, and the orbit control is not performed by default. This realizes timely output of attitude jet propulsion under the control of the thruster, avoiding instability caused by delay in the control system of the large flexible satellite. The design of two jet outputs within one control cycle enables rapid output of orbit control jet propulsion. Attached Figure Description

[0031] Figure 1 Flowchart of the thruster control method provided for the invention; Detailed Implementation

[0032] A thruster control method to ensure attitude stability and orbit control efficiency involves the following steps: First, within each control cycle of the computer, the required attitude control jet output for each thruster is calculated based on the satellite's current angle and angular velocity. Then, the required orbit control jet output is calculated based on the number of orbital elements to be adjusted. Next, thrusters requiring both attitude control and orbit control output in the current cycle are selected and marked with an "attitude-orbit reuse" flag. Then, orbit control thruster combinations containing the thrusters marked with the "attitude-orbit reuse" flag are selected, and all thrusters within the combination are marked with a "two jets required per cycle" flag. Finally, thrusters marked with "two jets required per cycle" are given two jet pulse width outputs depending on the specific circumstances.

[0033] Thrust control methods that ensure attitude stability and orbital control efficiency, such as Figure 1 As shown, the specific steps include:

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

[0035] Select the thruster that performs both attitude control jet output and trajectory control jet output at the current beat, and mark it as an attitude and trajectory reuse device.

[0036] Based on the satellite orbit adjustment direction of the thrusters with attitude and orbit reuse identifiers, the thrusters in the current adjustment direction are re-identified and grouped.

[0037] The thruster after secondary identification and grouping is subject to dual jet output control.

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

[0039] The satellite's current angle and angular velocity are collected in real time by measuring sensors.

[0040] Based on the satellite's three-axis control torque, determine the pre-set attitude control thrusters corresponding to the satellite's three axes;

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

[0042] Based on the adjustment required for the satellite attitude control mission, determine the required velocity increment of the satellite in the corresponding direction, determine the pre-set orbit control thrusters corresponding to the three axes of the satellite, and calculate the jet pulse width of the orbit control thrusters in each direction.

[0043] The method for selecting a thruster that simultaneously outputs attitude control and trajectory control at the current beat is as follows:

[0044] Establish two 1×n dimensional matrices, 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 jet, 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 an AND operation on the attitude control jet usage state matrix A and the orbital jet usage state matrix B to obtain the thrusters that are simultaneously occupied by attitude control and orbital control, and mark the determined thrusters with attitude and orbital reuse flags.

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

[0047] Based on the satellite orbit adjustment direction of the thrusters with attitude and orbit reuse indicators, select the thrusters that need to perform two orbit control jets in any cycle within the current control period. After screening, set a secondary indicator for all thrusters that meet the conditions. The secondary indicator indicates that two jets are required in one cycle.

[0048] The method for controlling the dual jet output of the grouped thrusters is as follows:

[0049] Two jet output commands are sent to the thrusters that need to release the jet mark twice within a single cycle. Select any thruster that needs to perform attitude control jet output and trajectory control jet output separately in any cycle. The first output command is the attitude control pulse width time, and the second output command is the trajectory control pulse width time.

[0050] For the other thrusters that require two jet ejection marks within one cycle, the first output command is 0, and the second output command is the orbital control pulse width time.

[0051] Within any given cycle, except for the thrusters that require separate attitude control and trajectory control jet outputs in one cycle, all other thrusters, regardless of whether they have been marked, perform jet output control once per cycle.

[0052] The orbit control thrusters are set 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 coordinate system. When selecting a thruster that needs to perform two control outputs in any cycle, the thruster is selected based on whether it is participating in the satellite's directional adjustment. The thruster that needs to perform two jets in one cycle is identified as the one that needs to perform two jets in one cycle.

[0053] When the thruster needs to output jet for attitude control and jet for trajectory control at any time, the attitude control jet pulse width shall be given priority.

[0054] The thruster is output with two pulse widths per cycle to reduce on-board delay and ensure satellite attitude control stability.

[0055] The following description, in conjunction with the accompanying drawings and preferred embodiments, provides further details:

[0056] In the current embodiment, the thruster control method that ensures stable attitude control while improving orbit control efficiency includes:

[0057] 1) Assign attitude control jets and trajectory control jets to each thruster in the current control cycle.

[0058] Both the satellite's angle and angular velocity can be obtained in real time through the measurement sensor. Based on the controller designed for the satellite's three axes, the control torque required to be output for the three axes can be calculated. According to the combination of attitude control thrusters pre-installed on the satellite, the satellite selects the corresponding thruster for each axis and converts the control torque into the jet pulse width (i.e., the jet time of each jet) of the corresponding thruster.

[0059] Based on the required adjustments to the satellite's orbital elements, the resulting velocity increments in the corresponding directions are converted into the required changes in the satellite's velocity. Then, according to the pre-programmed combinations of orbital control thrusters on the satellite, the total time required for each thruster to eject air in each direction is calculated.

[0060] 2) Select the nozzles that are simultaneously occupied by attitude control jets and trajectory control jets.

[0061] Establish two 1×n dimensional matrices A / B, 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 a thruster is in use, assign a value of 1 to the corresponding position element; otherwise, assign a value of 0 to the corresponding position element.

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

[0063] By performing an AND operation on matrices A and B, we can obtain the thrusters that are simultaneously used by attitude control and orbit control. These thrusters are then identified, and a "attitude and orbit reuse" flag is set.

[0064] 3) Select a thruster that requires two jet outputs per cycle.

[0065] The thruster combination used for orbit control needs to jet simultaneously to minimize the interference torque on the satellite; otherwise, the satellite attitude will overshoot or even diverge. Therefore, it is necessary to select the orbit control combination in which the thruster reused by attitude control is located, and to mark all thrusters in this combination with the "two jets required in one cycle" flag.

[0066] 4) Implement two jet outputs for special thruster assemblies.

[0067] For thrusters marked with "two jets required within one cycle", two jet outputs are performed. For thrusters that reuse 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 a thruster in a given cycle is simultaneously occupied by both attitude control jets and orbit control jets, the thruster combination performing orbit control operates in a two-output manner within one cycle. In the first cycle, attitude control pulse width commands are sent to the multiplexed thruster; in the second cycle, orbit control pulse width commands are sent to the remaining thrusters in the combination. This command transmission method ensures timely output of attitude control pulse widths, guaranteeing the stability of satellite attitude control; simultaneously, it saves orbit control output time, improving guidance efficiency and accuracy.

[0069] Example:

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

[0071] The thrusters for satellite +X direction orbit control are numbered a1 / b1 / a2 / b2, and the thrusters for -X direction orbit control are numbered a3 / b3 / a4 / b4; the thrusters for +Y direction orbit control are numbered a5 / b5 / a6 / b6, and the thrusters 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 the thrusters for -Z direction orbit control are numbered a11 / b11 / a12 / b12.

[0072] Table 1. Attitude Control Thruster Combination Table

[0073] Satellite control axis The thruster used positive rolling axis a5 / b5 negative rolling 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. Combination Table for Track Control Thrusters

[0075]

[0076]

[0077] (1) Assign attitude control jets and trajectory 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 300 seconds of jet propulsion and the +Z direction requires 200 seconds of jet propulsion, the current cycle requires thrusters a1 / b1 / a2 / b2 and a9 / b9 / a10 / b10 to operate.

[0079] The current satellite's three-axis attitude is controlled by jet propulsion. Based on the received satellite attitude and angular velocity, the controller calculates that the attitude control requires control torque from the positive roll axis, negative pitch axis, and positive yaw axis. The current cycle 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 simultaneously occupied by attitude control jet and trajectory control jet.

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

[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 an attitude control jet usage state matrix B, and assign values ​​to matrix B according to the current trajectory control thruster usage status.

[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] The results show that the thrusters that are simultaneously occupied by 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 cycle.

[0088] The thrusters required for satellite orbit adjustment in the +Z direction are a9 / b9 / a10 / b10. They must work in pairs simultaneously; otherwise, they will generate interfering torque on the satellite, thus affecting its attitude.

[0089] The thrusters numbered a9 / b9 participate in the orbital adjustment of the satellite in the +Z direction. The thrusters a10 / b10 also participate in the orbital control in the +Z direction. Therefore, the four thrusters numbered a9 / b9 / a10 / b10 are marked with the sign "two jets are required in one cycle".

[0090] (4) Implement two jet outputs for a special thruster assembly.

[0091] If the satellite's control cycle is 0.5 seconds, the attitude control pulse width is generally small. To reduce system latency and ensure the stability of highly flexible satellites, attitude control thrusters need to be output promptly. Orbital thrusters are generally longer. If the orbital control thrusters are not occupied, the thrust pulse width of the control cycle is output each cycle until the required thrust duration is exhausted.

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

[0093] As can be clearly seen from the thruster pulse width allocation above, the jet pulse width calculated by attitude control is output in real time, and the jet pulse width output time of trajectory control is only wasted on the time of attitude jet pulse width output.

[0094] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0095] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A thruster control method for ensuring attitude stability and orbit control efficiency, characterized by Comprise: Pre-set the attitude control jet of each thruster in the current control cycle, orbit control jet; Select the thruster that outputs attitude control jet and orbit control jet at the current beat, and mark the attitude and orbit multiplexing; According to the satellite orbit adjustment direction of the thruster with attitude and orbit multiplexing mark, mark the thrusters in the current adjustment direction twice; Double jet output control is performed on the thrusters after the second mark grouping; The double jet output control method of the grouped thrusters is: Send two jet output commands to the thrusters that need to jet twice in one beat, select the thrusters that need to output attitude control jet and orbit control jet respectively in any beat, the first output command is attitude control pulse width time, and the second output command is orbit control pulse width time; For the thrusters that need to jet twice in the remaining one beat, the first output command is 0, and the second output command is orbit control pulse width time; When in any beat, in addition to the thrusters that need to output attitude control jet and orbit control jet respectively, the remaining thrusters perform one-beat jet output control regardless of whether they have been marked or not; The orbit control thrusters are arranged in pairs and installed relative to the satellite center of mass, and the jet direction of the orbit control thrusters is set to realize three-axis six-direction jet based on the satellite body coordinate system; when selecting the thrusters that need to output control twice in any beat, the thrusters participating in satellite adjustment in any direction are judged to select the thrusters that need to jet twice in one beat.

2. The thruster control method of claim 1, wherein: The pre-set method of the attitude control jet and orbit control jet of each thruster is: Real-time acquisition of satellite angle and satellite angular velocity is performed by measuring sensor; Satellite three-axis control moment is calculated according to satellite angle and satellite angular velocity, and satellite three-axis respectively corresponding pre-installed attitude control thrusters are determined according to the satellite three-axis control moment; Satellite three-axis control moment is converted into jet pulse width of the corresponding attitude control thrusters; The required velocity increment of the satellite in the corresponding direction is determined according to the required adjustment amount of the satellite attitude control task, the satellite three-axis respectively corresponding pre-installed orbit control thrusters are determined, and the jet pulse width of the orbit control thrusters in each direction is calculated.

3. The thruster control method of claim 1, wherein: The method for selecting the thrusters that output attitude control and orbit control at the current beat is: Two 1×n matrices are established, which are attitude control jet usage state matrix A and orbit control jet usage state matrix B. When any thruster needs to jet, 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; The attitude control jet usage state matrix A and the orbit control jet usage state matrix B are ANDed to obtain the thrusters occupied by attitude control and orbit control, and the attitude and orbit multiplexing mark is marked on the determined thrusters.

4. The thruster control method of claim 3, wherein: the attitude control jet usage state matrix A is established according to the calculated jet pulse width of the corresponding attitude control thruster; and the orbit control jet usage state matrix B is established according to the calculated jet pulse width of the orbit control of each thruster.

5. The thruster control method of claim 1, wherein: the satellite orbit adjustment direction of the thruster with the attitude and orbit multiplexing identifier is determined; each thruster in the current adjustment direction is selected; the thruster that needs to perform twice orbit control jet in any beat in the current control period is selected; and after the selection is completed, a twice identifier is set for all thrusters that meet the condition, and the twice identifier is the thruster that needs twice jet in one beat.

6. The thruster control method of claim 1, wherein: when the thruster needs to perform attitude control output jet and orbit control output jet in any beat, the attitude control jet pulse width is preferentially performed.

7. The thruster control method of claim 6, wherein: the thruster performs twice pulse width output in one beat to reduce the on-board delay and ensure the stability of the satellite attitude control. ​ ​ ​ ​

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