Intelligent orbit control method and system for ultra-low orbit satellite

Abstract

The application provides a kind of super low orbit satellite intelligent orbit control method and system, comprising the following steps: calculating the orbit plane semi-major axis deviation Δa and the descending node position deviation ΔL;According to the orbit plane semi-major axis deviation Δa and the descending node position deviation ΔL, control coefficient K is calculated;According to the control coefficient K, deviation threshold ha, hL is calculated;It is judged whether "deviation Δa exceeds deviation threshold ha" or "deviation ΔL exceeds deviation threshold hL", if it exceeds, the control instruction of thruster is calculated according to the orbit plane semi-major axis deviation Δa, the descending node position deviation ΔL and the control coefficient K, otherwise, the control instruction of thruster is zero.The application can make the satellite realize intelligent autonomous orbit height maintenance control when in orbit, and the precision of orbit maintenance can be significantly improved, so as to save the fuel of satellite carried thruster and prolong the in-orbit life of satellite.

Description

Technical Field

[0001] This invention relates to the field of satellite on-orbit orbit control technology, specifically to an intelligent orbit maintenance control method and system for ultra-low orbit satellites. Background Technology

[0002] Aerodynamic drag and aerodynamic torque are important environmental factors affecting the orbital altitude and attitude of ultra-low orbit satellites. Atmospheric density increases significantly as the orbit decreases. Foreign ultra-low orbit satellites operate in orbits of 180-300 km, but the atmospheric density in these ultra-low orbits is subject to uncertain fluctuations due to factors such as solar activity, seasonal changes, day-night cycle, illumination conditions, and geomagnetic field activity.

[0003] For satellites operating at orbital altitudes of 180–300 km, the orbital decay rate reaches the kilometer level per day, requiring frequent orbital altitude increases to maintain an altitude suitable for normal payload operation. Furthermore, achieving control accuracy at the level of hundreds of meters is difficult, making open-loop orbit control challenging. Therefore, controlling the satellite under closed-loop conditions, i.e., achieving autonomous operation of the satellite in terms of orbital control, has become an urgent need. Consequently, it is necessary to update the algorithms and solutions for specific problems to improve control accuracy and meet the requirements of intelligent autonomous control.

[0004] Patent document CN113378290A discloses a method for maintaining the orbit of a very low Earth orbit (ULE) satellite, comprising: setting satellite parameters and atmospheric parameters; constructing an orbital dynamics model based on the satellite parameters and atmospheric parameters, wherein the satellite parameters include satellite orbital parameters, basic satellite parameters, and initial satellite orbital control parameters; constructing an optimization model; optimizing the initial satellite orbital control parameters based on the optimization model, the orbital dynamics model, the satellite orbital parameters, and the basic satellite parameters to obtain optimized orbital control parameters, wherein the optimization model includes multiple optimization constraints; and controlling an air-breathing propulsion system to collect and expel air according to the optimized orbital control parameters to maintain the ULE satellite's orbit. Patent document CN111989265A discloses a method for autonomous orbit maintenance of an ultra-low orbit satellite. The method includes: Step 1, setting the satellite's working orbit range and estimating the magnitude of atmospheric drag; Step 2, analyzing the magnitude of noise in the inertial acceleration measurement system based on the magnitude of atmospheric drag, and obtaining the noise analysis results of the inertial acceleration measurement system; Step 3, setting the parameters of the low-thrust execution system based on the noise analysis results of the inertial acceleration measurement system, and performing on-orbit calibration of the inertial acceleration measurement system and the low-thrust execution system to obtain the calibrated inertial acceleration output results; and Step 4, setting the orbit control low-thrust output algorithm of the low-thrust execution system based on the calibrated inertial acceleration output results. Patent document CN106542119B discloses an on-board autonomous orbit maintenance control method, including: determining the satellite's orbital position and satellite velocity information; calculating and obtaining the satellite's average orbital parameters, including the average semi-major axis, based on the satellite's orbital position and satellite velocity information; if the obtained average semi-major axis is lower than the lower limit of the designed average semi-major axis, then the thrusters are activated to raise the average semi-major axis; when the obtained average semi-major axis rises to the upper limit of the designed average semi-major axis, then the thrusters are deactivated. However, the above-mentioned patent documents all perform closed-loop control based solely on existing orbital information and cannot achieve autonomous control.

[0005] Patent document CN113998150A discloses an all-electric propulsion orbit maintenance system for ultra-low Earth orbit (ULE) satellites, comprising a GNSS receiver, an atmospheric density measurement unit, a satellite management unit, and an electric propulsion system. The GNSS receiver provides the ULE satellite's state vector in a ground-fixed coordinate system. The atmospheric density detection unit acquires atmospheric density data and inversely calculates the ULE satellite's orbital altitude. The electric propulsion system, based on the orbit maintenance control law transmitted from the satellite management unit, allocates thrust parameters and generates thrust. The satellite management unit comprehensively determines the ULE satellite's orbital information, processes it to generate satellite spatial trajectory error, and then, based on this error, determines the orbit maintenance control law using an orbit maintenance algorithm, sending the control law to the electric propulsion system to complete orbit maintenance control. However, this patent document does not achieve autonomous control. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide an intelligent orbit control method and system for ultra-low orbit satellites.

[0007] The present invention provides an intelligent orbit maintenance control method for ultra-low Earth orbit satellites, comprising the following steps:

[0008] Step 1: Calculate the deviation of the major axis of the track in the horizontal half-section Δa and the deviation of the descending intersection point ΔL;

[0009] Step 2: Calculate the control coefficient K based on the deviation of the track's horizontal semi-major axis Δa and the deviation of the descending intersection point position ΔL;

[0010] Step 3: Calculate the deviation thresholds ha and hL based on the control coefficient K;

[0011] Step 4: Determine whether "deviation Δa exceeds deviation threshold ha" or "deviation ΔL exceeds deviation threshold hL". If it does, calculate the control command of the thruster based on the deviation of the semi-major axis of the track Δa, the deviation of the descending intersection point ΔL, and the control coefficient K. Otherwise, the control command of the thruster is zero.

[0012] Preferably, in step 1, the deviation of the horizontal semi-major axis Δa and the deviation of the descending intersection point ΔL are calculated based on the recursive data of the reference orbit without attenuation and the GNSS orbit determination data.

[0013] Preferably, the specific process for calculating the deviation Δa of the semi-major axis of the track is as follows: the absolute value of the semi-major axis of the "track height of the GNSS orbit determination data" minus the absolute value of the semi-major axis of the "unattenuated reference track recursive data".

[0014] Preferably, the specific process for calculating the descending intersection position deviation ΔL is as follows: the absolute value of the descending intersection position of the GNSS orbit determination data minus the descending intersection position of the unattenuated reference orbit recursive data.

[0015] Preferably, in step 2, the control coefficient K is calculated based on the space environment detection data, the deviation of the orbit's horizontal semi-major axis Δa, and the deviation of the descending intersection point position ΔL.

[0016] Preferably, in step 2, the control coefficient K is calculated as follows: K = 1 - (proportional constant 1 * Δa + proportional constant 2 * ΔL).

[0017] Preferably, the specific process for calculating the deviation threshold ha is as follows: ha = semi-major axis theoretical attenuation deviation threshold * K.

[0018] Preferably, the specific process for calculating the deviation threshold hL is as follows: hL = theoretical attenuation deviation threshold at the descending intersection position * K.

[0019] Preferably, the specific process of calculating the control command of the thruster based on the track horizontal semi-major axis deviation Δa, the descending intersection point position deviation ΔL, and the control coefficient K is as follows: Control command = Ideal control command * K.

[0020] This invention also provides an intelligent orbit maintenance control system for ultra-low Earth orbit satellites, comprising the following modules:

[0021] Module M1: Calculates the deviation of the major axis of the track in the horizontal half-section Δa and the deviation of the descending intersection point ΔL;

[0022] Module M2: Calculate the control coefficient K based on the track horizontal semi-major axis deviation Δa and the descending intersection point position deviation ΔL;

[0023] Module M3: Calculate the deviation thresholds ha and hL based on the control coefficient K;

[0024] Module M4: Determine whether "deviation Δa exceeds deviation threshold ha" or "deviation ΔL exceeds deviation threshold hL": If "deviation Δa exceeds deviation threshold ha" or "deviation ΔL exceeds deviation threshold hL", then calculate the thruster control command based on the track horizontal semi-major axis deviation Δa, the descending intersection position deviation ΔL, and the control coefficient K; if "deviation Δa does not exceed deviation threshold ha" and "deviation ΔL does not exceed deviation threshold hL", then the thruster control command is zero.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. This invention enables intelligent and autonomous orbital altitude maintenance control for satellites during on-orbit operation;

[0027] 2. This invention can significantly improve the accuracy of track maintenance;

[0028] 3. This invention can significantly save the propulsion fuel carried by the satellite and extend the satellite's on-orbit life. Attached Figure Description

[0029] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0030] Figure 1 This is a flowchart illustrating the intelligent orbit control method for ultra-low orbit satellites according to the present invention. Detailed Implementation

[0031] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0032] Example 1:

[0033] This embodiment provides an intelligent orbit maintenance control method for ultra-low Earth orbit satellites, including the following steps:

[0034] Step 1: Calculate the horizontal semi-major axis deviation Δa and the descending node position deviation ΔL. Based on the recursive data of the unattenuated reference orbit and the GNSS orbit determination data, calculate the horizontal semi-major axis deviation Δa and the descending node position deviation ΔL. The specific process for calculating the horizontal semi-major axis deviation Δa is: subtract the absolute value of the semi-major axis of the unattenuated reference orbit recursive data from the "track height of the GNSS orbit determination data". The specific process for calculating the descending node position deviation ΔL is: subtract the absolute value of the descending node position of the unattenuated reference orbit recursive data from the "descending node position of the GNSS orbit determination data".

[0035] Step 2: Based on the space environment exploration data, the orbital semi-major axis deviation Δa, and the descending node position deviation ΔL, calculate the control coefficient K. Specifically, the control coefficient K is calculated as: K = 1 - (proportional constant 1 * Δa + proportional constant 2 * ΔL). Proportional constant 1 and proportional constant 2 are determined based on the simulation model computer results. The specific calculation process will involve some relevant satellite parameters, such as satellite mass.

[0036] Step 3: Based on the control coefficient K, calculate the deviation thresholds ha and hL. The specific process for calculating the deviation threshold ha is: ha = theoretical attenuation deviation threshold of the semi-major axis * K. The specific process for calculating the deviation threshold hL is: hL = theoretical attenuation deviation threshold of the descending intersection position * K. The theoretical attenuation deviation threshold of the semi-major axis is the theoretical attenuation deviation threshold of the track's semi-major axis, and the theoretical attenuation deviation threshold of the descending intersection position is the theoretical attenuation deviation threshold of the track's semi-major axis.

[0037] Step 4: Determine whether "deviation Δa exceeds deviation threshold ha" or "deviation ΔL exceeds deviation threshold hL". If it does, calculate the thruster's control command based on the track's horizontal semi-major axis deviation Δa, the descending intersection point position deviation ΔL, and the control coefficient K. Otherwise, the thruster's control command is zero. The specific process for calculating the thruster's control command based on the track's horizontal semi-major axis deviation Δa, the descending intersection point position deviation ΔL, and the control coefficient K is as follows: Control command = Ideal control command * K.

[0038] Example 2:

[0039] This embodiment provides an intelligent orbit maintenance control system for ultra-low Earth orbit satellites, including the following modules:

[0040] Module M1: Calculates the deviation of the major axis of the track in the horizontal half-section Δa and the deviation of the descending intersection point ΔL;

[0041] Module M2: Calculate the control coefficient K based on the track horizontal semi-major axis deviation Δa and the descending intersection point position deviation ΔL;

[0042] Module M3: Calculate the deviation thresholds ha and hL based on the control coefficient K;

[0043] Module M4: Determine whether "deviation Δa exceeds deviation threshold ha" or "deviation ΔL exceeds deviation threshold hL": If "deviation Δa exceeds deviation threshold ha" or "deviation ΔL exceeds deviation threshold hL", then calculate the thruster control command based on the track horizontal semi-major axis deviation Δa, the descending intersection position deviation ΔL, and the control coefficient K; if "deviation Δa does not exceed deviation threshold ha" and "deviation ΔL does not exceed deviation threshold hL", then the thruster control command is zero.

[0044] Example 3:

[0045] Those skilled in the art can understand this embodiment as a more specific description of Embodiment 1 and Embodiment 2.

[0046] This embodiment provides an intelligent orbit maintenance control method for ultra-low Earth orbit satellites, including the following steps:

[0047] Step S1: Calculate the deviation of the major axis of the track in the horizontal half-section Δa and the deviation of the descending intersection point ΔL;

[0048] Step S2: Calculate the control coefficient K;

[0049] Step S3: Calculate the deviation thresholds ha and hL from the control coefficient K;

[0050] Step S4: Calculate the thruster control commands.

[0051] Step S1 specifically includes: calculating the horizontal semi-major axis deviation Δa and the descending intersection position deviation ΔL from the recursive data of the unattenuated reference orbit and the GNSS orbit determination data.

[0052] Step S2 specifically includes: calculating the control coefficient K based on space environment detection data, the orbital horizontal semi-major axis deviation Δa, and the descending node position deviation ΔL. The control coefficient K here incorporates the combined effects of three factors: atmospheric drag, orbital altitude deviation, and ground position deviation.

[0053] Step S3 specifically includes: calculating the deviation thresholds ha and hL based on the calculated control coefficient K. The deviation threshold hL can be standardized by converting it to the orbital altitude deviation. Furthermore, the value of the orbital altitude deviation ha should achieve the following effect: when the satellite's orbital altitude decays to the height relative to the nominal orbit - ha, the orbital rise control amount is 2ha. After a certain period of altitude decay, when the satellite's altitude reaches the nominal altitude, the satellite's operating position is exactly the same as its operating position without attenuation.

[0054] Step S4 specifically includes: determining whether "deviation Δa exceeds deviation threshold ha" or "deviation ΔL exceeds deviation threshold hL". If it exceeds, the control command of the thruster is calculated from the deviation of the track horizontal semi-major axis Δa, the deviation of the descending intersection point position ΔL, and the coefficient K; otherwise, the control command of the thruster is zero.

[0055] Based on various data and information measured and received by the satellite, this invention enables the satellite to achieve intelligent and autonomous orbital altitude maintenance control during its on-orbit operation, and can significantly improve the accuracy of orbital maintenance, thereby saving the satellite's on-orbit thruster fuel and extending the satellite's on-orbit lifespan.

[0056] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0057] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for intelligent orbit maintenance control of ultra-low orbit satellites, characterized in that, Includes the following steps: Step 1: Calculate the deviation of the major axis of the track in the horizontal half-section Δa and the deviation of the descending intersection point ΔL; Step 2: Calculate the control coefficient K based on the deviation of the track's horizontal semi-major axis Δa and the deviation of the descending intersection point position ΔL; Step 3: Calculate the deviation thresholds ha and hL based on the control coefficient K; Step 4: Determine whether "deviation Δa exceeds deviation threshold ha" or "deviation ΔL exceeds deviation threshold hL". If it does, calculate the control command of the thruster based on the deviation of the semi-major axis of the track Δa, the deviation of the descending intersection point ΔL, and the control coefficient K. Otherwise, the control command of the thruster is zero.

2. The intelligent orbit control method for ultra-low orbit satellites according to claim 1, characterized in that, In step 1, the deviation of the horizontal semi-major axis of the track Δa and the deviation of the descending intersection point ΔL are calculated based on the recursive data of the reference track without attenuation and the GNSS orbit determination data.

3. The intelligent orbit control method for ultra-low orbit satellites according to claim 2, characterized in that, The specific process for calculating the deviation Δa of the semi-major axis of the track is as follows: subtract the absolute value of the semi-major axis of the unattenuated reference track from the track height of the GNSS orbit determination data.

4. The intelligent orbit maintenance control method for ultra-low orbit satellites according to claim 2, characterized in that, The specific process for calculating the descending intersection position deviation ΔL is as follows: subtract the absolute value of the descending intersection position of the GNSS orbit determination data from the descending intersection position of the reference orbit without attenuation.

5. The intelligent orbit maintenance control method for ultra-low orbit satellites according to claim 1, characterized in that, In step 2, the control coefficient K is calculated based on the space environment detection data, the deviation of the orbit's horizontal semi-major axis Δa, and the deviation of the descending intersection point ΔL.

6. The intelligent orbit maintenance control method for ultra-low orbit satellites according to claim 5, characterized in that, In step 2, the control coefficient K is calculated as follows: K = 1 - (proportional constant 1 * Δa + proportional constant 2 * ΔL).

7. The intelligent orbit maintenance control method for ultra-low orbit satellites according to claim 1, characterized in that, The specific process for calculating the deviation threshold ha is as follows: ha = theoretical attenuation deviation threshold of semi-major axis * K.

8. The intelligent orbit maintenance control method for ultra-low orbit satellites according to claim 1, characterized in that, The specific process for calculating the deviation threshold hL is as follows: hL = theoretical attenuation deviation threshold at the descending intersection position * K.

9. The intelligent orbit control method for ultra-low orbit satellites according to claim 1, characterized in that, The specific process of calculating the control command of the thruster based on the track semi-major axis deviation Δa, the descending intersection position deviation ΔL, and the control coefficient K is as follows: Control command = Ideal control command * K.

10. An intelligent orbit maintenance control system for ultra-low orbit satellites, characterized in that, Includes the following modules: Module M1: Calculates the deviation of the major axis of the track in the horizontal half-section Δa and the deviation of the descending intersection point ΔL; Module M2: Calculate the control coefficient K based on the track horizontal semi-major axis deviation Δa and the descending intersection point position deviation ΔL; Module M3: Calculate the deviation thresholds ha and hL based on the control coefficient K; Module M4: Determines whether "deviation Δa exceeds deviation threshold ha" or "deviation ΔL exceeds deviation threshold hL": If "deviation Δa exceeds deviation threshold ha" or "deviation ΔL exceeds deviation threshold hL", then calculates the thruster control command based on the track horizontal semi-major axis deviation Δa, the descending intersection point position deviation ΔL, and the control coefficient K; if "deviation Δa does not exceed deviation threshold ha" and "deviation ΔL does not exceed deviation threshold hL", then the thruster control command is zero.

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