Spacecraft angular momentum control method and system

Abstract

The present invention provides a spacecraft angular momentum control method and system, comprising: in the first stage of orbit transfer, closing the momentum wheel to avoid the loss of momentum unloading, wherein in the first stage of orbit transfer, the onboard attitude chemical thruster performs satellite attitude control and adjustment; in the second stage of orbit transfer, pre-judging the unloading amount, and performing momentum unloading according to the predicted result and the vector adjustment range, wherein in the first stage of orbit transfer, the electric thruster performs satellite orbit change; and in the third stage of orbit transfer, closing the momentum wheel to avoid the loss of momentum unloading, wherein in the third stage of orbit transfer, the onboard attitude chemical thruster performs satellite attitude control and fixed-point capture control.

Description

Technical Field

[0001] The present invention relates to the field of aerospace technology, and in particular to a spacecraft angular momentum control method and system. Background Art

[0002] Electric propulsion systems convert solar energy into electricity, which is then converted into mechanical energy. Traditional chemical propulsion systems convert chemical energy into mechanical energy through chemical reactions. Electric propulsion systems, also known as electric rocket engines, generate thrust without relying on chemical combustion. Their advantage is that they eliminate the need for solid or liquid fuel, eliminating the complex storage tanks, piping, engine combustion chambers, nozzles, and associated cooling mechanisms, significantly reducing the amount of fuel a spacecraft carries.

[0003] As the core component of a Hall thruster electric propulsion system, its operating thrust characteristics determine the system's thrust output characteristics and also influence its application strategy on spacecraft. According to the propulsion system's operating principle, ions generated by the Hall thruster, under the influence of the orthogonal electromagnetic fields in the acceleration region, form a plasma jet with a velocity of approximately 20,000 m / s. The ion beam current typically reaches 1 to 10 A, depending on the thruster's discharge power. This ion beam current interacts with the thruster's radial magnetic field (approximately 0.02 to 0.04 T), generating a directional Lorentz force that deflects the ion trajectory. This directional reaction force also acts on the thruster. Therefore, the combined action of a large ion beam causes the thruster to experience a torque along its axis.

[0004] Taking a 1kW Hall-effect thruster as an example, it generates a torque of approximately 1×10⁻4 N·m along its axis during operation. Continuous operation for 24 hours can generate an accumulated angular momentum of 8.64 N·ms. Therefore, prolonged operation of a Hall-effect thruster system can significantly accumulate angular momentum in the spacecraft due to self-generated torque, adversely affecting attitude control. This accelerates the accumulation of angular momentum, increases the burden on the attitude and orbit control system, and consumes additional propellant for momentum unloading. Summary of the Invention

[0005] The purpose of the present invention is to provide a spacecraft angular momentum control method and system to solve the problem that the accumulation of angular momentum of existing spacecraft leads to excessive burden on the attitude and orbit control system.

[0006] To solve the above technical problems, the present invention provides a spacecraft angular momentum control method, comprising:

[0007] During the first stage of orbit transfer, the momentum wheel is shut down to avoid the loss of momentum unloading, wherein during the first stage of orbit transfer, the onboard attitude chemical thruster is used to control and adjust the satellite attitude;

[0008] In the second stage of the orbit transfer, the unloading amount is predicted in advance, and momentum unloading is performed according to the prediction result and the vector adjustment range, wherein in the first stage of the orbit transfer, the electric thruster is used to change the satellite orbit; and

[0009] In the third stage of orbit transfer, the momentum wheel is turned off to avoid the loss of momentum unloading. In the third stage of orbit transfer, the onboard attitude chemical thrusters are used to perform satellite attitude control and fixed-point capture control.

[0010] Optionally, the spacecraft angular momentum control method further includes:

[0011] Transferring small geostationary satellites from the Earth Transfer Orbit to the Geostationary Orbit using three orbit transfer stages, including:

[0012] In the first stage of orbit transfer, the orbit change chemical thrusters are ignited to quickly raise the orbit perigee altitude to above the first altitude, and the domestic measurement and control arc is not less than the threshold measurement and control arc to execute the orbit change as the control target;

[0013] In the second stage of the orbit transfer, the electric thrusters adjust the orbit perigee height to a second height, and at the same time, the orbit inclination is adjusted to a threshold inclination, and the orbit eccentricity is adjusted to a threshold eccentricity to perform the orbit transfer as a control target;

[0014] In the third stage of orbit transfer, the onboard attitude chemical thrusters are ignited to enter the target orbital position accuracy range and perform point capture for the target.

[0015] Optionally, the spacecraft angular momentum control method further includes:

[0016] The first altitude is 8000 km, the second altitude is 35786 km, the threshold measurement and control arc is 3 hours, the threshold inclination angle is 0 degrees, and the threshold eccentricity is 0 degrees;

[0017] The first stage of the orbit transfer also includes the following steps:

[0018] The orbit-changing chemical thruster raises the orbital perigee altitude of the small geostationary orbit satellite to above a first altitude within 120 hours;

[0019] After the orbital perigee altitude of the small geostationary orbit satellite is raised to a first altitude, the orbit-changing chemical thruster is turned off.

[0020] Optionally, in the spacecraft angular momentum control method, the following steps are further performed during the second stage of the orbit transfer:

[0021] Before the electric thruster performs the orbit change, a first orbit determination is performed to obtain the number of fine orbit elements of the second-stage initial orbit, the total mass of the satellite, and the center of mass, and the state of the electric thruster is set according to the result of the first orbit determination;

[0022] After the control target of the second stage of the orbit transfer is achieved, shutting down the electric thruster;

[0023] 1.5 hours before the electric thruster enters perigee, the electric thruster automatically shuts down, and the small geostationary orbit satellite automatically switches from the orbit change mode when the electric thruster is ignited to the earth holding mode;

[0024] 1.5 hours after the electric thruster enters perigee, the small geostationary orbit satellite automatically switches from the ground-keeping mode to the orbit-changing and sun-facing mode when the electric thruster is ignited, and the electric thruster is automatically turned on and ignited for orbit change.

[0025] Optionally, in the spacecraft angular momentum control method, the following steps are further performed during the third stage of the orbit transfer:

[0026] Before the onboard attitude control chemical thrusters are ignited, a second orbit determination is performed to obtain the number of initial orbit elements, the satellite's total mass, and its center of mass for the third stage of orbit transfer, and the state of the onboard attitude control chemical thrusters is set according to the results of the second orbit determination;

[0027] After entering the target orbit accuracy range, the attitude control chemical thruster is turned off and the working fluid flow of the orbit change chemical thruster is cut off to ensure the safety of the propulsion system after positioning.

[0028] Optionally, in the spacecraft angular momentum control method, the momentum unloading in the second stage of the orbit transfer is performed at the orbit transfer perigee, and the momentum unloading in the second stage of the orbit transfer is performed by an electric thruster or an onboard attitude chemical thruster;

[0029] During the first and third stages of orbital transfer, the electric thrusters and momentum wheels are shut down, and satellite attitude control and adjustment are achieved only by relying on the on-board chemical thrusters.

[0030] Optionally, the spacecraft angular momentum control method further includes:

[0031] In the second stage of orbit transfer, when the electric thruster is changing its orbit, the ground will analyze the telemetry data transmitted from the satellite and predict the required unloading amount and the adjustment design angle range of the electric propulsion vector control mechanism, and decide whether to use the electric thruster or the onboard attitude chemical thruster to perform momentum unloading, so as to implement the unloading strategy 1 to 2 orbits in advance.

[0032] Optionally, the spacecraft angular momentum control method further includes:

[0033] In the second stage of orbit transfer, based on the lifespan and design adjustment angle range of the electric propulsion vector control mechanism, when both meet the requirements, the onboard attitude chemical thrusters or trajectory transfer chemical thrusters are shut down, the electric thrusters are turned on, and the electric thrusters are adjusted to perform momentum unloading.

[0034] When the service life or adjustment design angle range is not met, on-board attitude chemical thrusters are used for momentum unloading.

[0035] Optionally, in the described spacecraft angular momentum control method, based on the unloading strategy noted on the ground and the onboard angular velocity telemetry, the onboard vehicle autonomously judges and executes the unloading strategy 1.5 hours before entering perigee, and completes the unloading and related safety operations within a total of 3 hours before and after perigee, and autonomously enters the normal electric propulsion trajectory change procedure 1.5 hours after leaving perigee.

[0036] The present invention also provides a spacecraft angular momentum control system, comprising:

[0037] a first controller configured to shut down the momentum wheel to avoid loss of momentum unloading during a first stage of orbit transfer, wherein during the first stage of orbit transfer, the onboard attitude chemical thruster is enabled to perform satellite attitude control and adjustment;

[0038] The second controller is configured to predict the unloading amount in advance during the second stage of the orbit transfer, and perform momentum unloading according to the prediction result and the vector adjustment range, wherein during the first stage of the orbit transfer, the electric thruster is used to perform satellite orbit change; and

[0039] The third controller is configured to shut down the momentum wheel to avoid the loss of momentum unloading during the third stage of orbit transfer, wherein during the third stage of orbit transfer, the onboard attitude chemical thruster is enabled to perform satellite attitude control and fixed-point capture control.

[0040] In the spacecraft angular momentum control method and system provided by the present invention, by shutting down the momentum wheel in the first stage of orbit transfer to avoid the loss of momentum unloading, in the second stage of orbit transfer, momentum unloading is performed according to the prediction result and the vector adjustment range, and in the third stage of orbit transfer, the momentum wheel is shut down to avoid the loss of momentum unloading. This realizes the characteristics of the three-stage orbit transfer of small geostationary orbit satellites, and proposes a method for momentum unloading of small geostationary orbit satellites during the three-stage orbit transfer process from the perspective of improving orbit change efficiency and reducing orbit change time. The spacecraft angular momentum control method of the present invention has the characteristics of high redundancy, clear logic, and strong feasibility. It is suitable for the hybrid propulsion system design of the miniaturized high-orbit satellite public platform and can effectively ensure the realization of the orbit transfer mission of the miniaturized high-orbit satellite. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a flow chart of a method for controlling spacecraft angular momentum according to an embodiment of the present invention;

[0042] Figure 2 This is a schematic diagram of the first stage of the process of the small geostationary satellite orbit transfer method according to an embodiment of the present invention;

[0043] Figure 3 This is a schematic diagram of the second stage of the process of the small geostationary orbit satellite orbit transfer method according to an embodiment of the present invention;

[0044] Figure 4 This is a schematic diagram of the third stage of the process of the small geostationary satellite orbit transfer method according to an embodiment of the present invention;

[0045] Figure 5 1. It is a schematic diagram of the change process of the orbit semi-major axis and orbit eccentricity in the orbit transfer method of a small geostationary orbit satellite according to one embodiment of the present invention;

[0046] Figure 6 The figure is a schematic diagram of the orbital inclination change process in the orbit transfer method of a small geostationary orbit satellite according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The spacecraft angular momentum control method and system proposed in the present invention are further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are highly simplified and not to exact scale, and are intended solely to facilitate and clearly illustrate the embodiments of the present invention.

[0048] In addition, unless otherwise stated, features in different embodiments of the present invention may be combined with each other. For example, a feature in the second embodiment may be substituted for a corresponding feature in the first embodiment having the same or similar function, and the resulting embodiment will also fall within the scope of disclosure or description of this application.

[0049] The core idea of ​​the present invention is to provide a spacecraft angular momentum control method and system to solve the problem that the existing spacecraft angular momentum accumulation causes excessive burden on the attitude and orbit control system.

[0050] To realize the above-mentioned concept, the present invention provides a spacecraft angular momentum control method and system, comprising: a first controller, configured to shut down the momentum wheel in the first stage of orbit transfer to avoid the loss of momentum unloading, wherein in the first stage of orbit transfer, the on-board attitude chemical thruster is enabled to perform satellite attitude control and adjustment; a second controller, configured to predict the unloading amount in advance in the second stage of orbit transfer, and perform momentum unloading according to the prediction result and the vector adjustment range, wherein in the first stage of orbit transfer, the electric thruster is enabled to perform satellite orbit change; and a third controller, configured to shut down the momentum wheel in the third stage of orbit transfer to avoid the loss of momentum unloading, wherein in the third stage of orbit transfer, the on-board attitude chemical thruster is enabled to perform satellite attitude control and fixed-point capture control.

[0051] The embodiment of the present invention discloses a momentum unloading method during the orbit transfer process of a small geostationary orbit satellite. Figure 1 As shown, it includes: in the first stage of orbit transfer, satellite attitude control and adjustment are realized by on-board attitude chemical thrusters, and the momentum wheels are closed to avoid unloading losses; in the second stage of orbit transfer, during the electric propulsion orbit change process, electric propulsion or attitude control chemical propulsion is selected at the orbit transfer perigee to carry out momentum unloading according to the advance predicted unloading amount and vector adjustment range; in the third stage of orbit transfer, satellite attitude control and fixed-point capture control are realized by on-board attitude chemical thrusters, and the momentum wheels are closed to avoid unloading losses.

[0052] The momentum unloading method for a small geostationary orbit satellite during orbital transfer disclosed in this embodiment is based on the characteristics of the three-stage orbital transfer of a small geostationary orbit satellite and is proposed from the perspective of improving orbit transfer efficiency and reducing orbit transfer time. The method has the characteristics of high orbit transfer efficiency, high redundancy, clear logic, and strong feasibility. It closely combines the characteristics of the three-stage orbital transfer of a small geostationary orbit satellite, adapts to the hybrid propulsion system design of a small high-orbit satellite public platform, and can effectively ensure the realization of the orbit transfer mission of a small high-orbit satellite.

[0053] This embodiment provides a method for transferring a small geostationary satellite orbit. Figures 2-4As shown, it includes: transferring a small geostationary orbit satellite from the Earth transfer orbit to the geostationary orbit through three stages, specifically including: in the first stage of orbit transfer, igniting the orbit change chemical thrusters to quickly increase the orbit perigee altitude to above the first altitude, and the domestic measurement and control arc is not less than the threshold measurement and control arc to perform orbit change for the control target; in the second stage of orbit transfer, the electric thrusters adjust the orbit perigee altitude to the second altitude, while adjusting the orbit inclination to the threshold inclination and the orbit eccentricity to the threshold eccentricity to perform orbit change for the control target; in the third stage of orbit transfer, igniting the attitude control chemical thrusters to enter the target orbit position accuracy range to perform fixed-point capture for the target.

[0054] In one embodiment of the present invention, Figures 5-6 As shown, in the small geostationary orbit satellite orbit transfer method, the first altitude is 8000 km, the second altitude is 35786 km, the threshold tracking arc is 3 hours, the threshold inclination is 0 degrees, and the threshold eccentricity is 0 degrees. During the first phase, the chemical thrusters for orbit transfer are further executed: raising the orbital perigee altitude of the small geostationary orbit satellite to above the first altitude within 120 hours; and shutting down the chemical thrusters after the orbital perigee altitude of the small geostationary orbit satellite has been raised to the first altitude.

[0055] In one embodiment of the present invention, the second stage further comprises: before the electric thruster performs orbit change, performing a first orbit measurement to obtain the number of fine orbit elements of the second stage initial orbit, the total mass of the satellite, and the center of mass, and setting the state of the electric thruster according to the result of the first orbit measurement; after the control target of the second stage is achieved, shutting down the electric thruster. The second stage further comprises: 1.5 hours before the electric thruster enters perigee, the electric thruster automatically shuts down, and the small geostationary orbit satellite automatically switches from the orbit change and solar mode when the electric thruster is ignited to the geoholding mode; 1.5 hours after the electric thruster enters perigee, the small geostationary orbit satellite automatically switches from the geoholding mode to the orbit change and solar mode when the electric thruster is ignited, and the electric thruster automatically powers on and ignites for orbit change.

[0056] In one embodiment of the present invention, in the small geostationary orbit satellite orbit transfer method, the third stage further comprises: performing a second orbit measurement before igniting the attitude control chemical thrusters to obtain the number of fine orbit elements of the third stage initial orbit, the satellite's total mass, and the center of mass; and setting the attitude control chemical thruster status based on the results of the second orbit measurement; and after entering the target orbit position accuracy range, shutting down the attitude control chemical thrusters and cutting off the working fluid flow of the orbit change chemical thrusters to ensure the safety of the propulsion system after positioning.

[0057] In one embodiment of the present invention, during both the first and third stages of orbital transfer, the onboard electric thrusters and momentum wheels are shut down, relying solely on the onboard chemical thrusters for attitude control and adjustment. During the second stage of orbital transfer, during the electric propulsion orbit change, ground forces analyze and predict the required unloading amount and the adjustment range of the electric propulsion vector control mechanism based on onboard telemetry data. This determines whether to use electric thrusters or attitude control thrusters for unloading, thereby implementing the unloading strategy one or two orbits in advance.

[0058] Specifically, during the second phase of orbital transfer, considering the lifespan and design adjustment angle range of the electric propulsion vector control mechanism, if both the lifespan and adjustment angle meet the requirements, the electric thrusters will be used for unloading after adjusting the electric thrust vector without activating other thruster systems or shutting down the electric thrusters. If the lifespan or adjustment angle are not met, the attitude control chemical thrusters will be used for unloading. During the second phase of orbital transfer, based on the unloading strategy specified on the ground and onboard angular velocity telemetry, the satellite will autonomously determine and execute the unloading strategy 1.5 hours before entering perigee. The unloading and related safety operations will be completed within a total of 3 hours before and after perigee. The normal electric propulsion orbit transfer procedure will be autonomously entered 1.5 hours after leaving perigee.

[0059] In one embodiment of the present invention, during the first stage of orbital transfer, onboard chemical thrusters are used to control and adjust the satellite's attitude, while the momentum wheels are shut down to avoid saturation and the resulting loss of onboard momentum unloading. Onboard chemical thrusters are used to achieve the first stage of the satellite's orbital change, which only changes the perigee altitude. This advantageous effect includes: using the chemical thrusters to rapidly raise the perigee altitude to over 8,000 km, while ensuring a domestic tracking and control arc of at least three hours. Only a small amount of chemical propellant is required to allow the satellite to escape the Van Allen radiation belt after the first orbital change, effectively protecting the satellite's safety.

[0060] During the second stage of orbital transfer, during the electric propulsion orbit change process, momentum unloading is carried out using either electric propulsion or attitude control chemical propulsion at the orbital transfer perigee, based on the pre-determined unloading amount and the vector adjustment range. The resulting benefits include: the vast majority of the orbit change process (the vast majority of the journey) is completed by electric propulsion, and the high specific impulse of electric propulsion can greatly reduce the weight of the orbit change fuel carried by the satellite, significantly reducing the weight of the entire satellite and gaining more payload capacity; during the electric propulsion orbit change process, when faced with momentum wheel saturation, attitude control chemical propulsion or electric propulsion unloading can be selected based on the detuning capability. This flexible selection method can greatly reduce the design difficulty of the detuning mechanism and increase its design life; unloading near perigee greatly increases the effective operating time of the electric propulsion orbit change, allowing the entire orbit change journey to be completed as quickly as possible.

[0061] During the third stage of orbital transfer, onboard chemical thrusters are used to control the satellite's attitude and capture position, while the momentum wheels are deactivated to avoid unloading losses. This approach offers several benefits: Because electric propulsion has low thrust, orbital insertion takes longer and the strategy for achieving orbital position is more complex (due to its low thrust, it may overshoot or fail to reach its target, requiring several more turns). However, chemical propulsion, with its high thrust, allows for smoother orbital insertion and higher positioning accuracy. Therefore, this approach not only saves time but also improves positioning accuracy and engineering feasibility.

[0062] The basic parameters of the three stages of orbital transfer are shown in Table 1:

[0063] Table 1

[0064]

[0065] The present invention also provides a spacecraft angular momentum control system, comprising: a first controller, configured to shut down the momentum wheel in the first stage of orbit transfer to avoid the loss of momentum unloading, wherein in the first stage of orbit transfer, the on-board attitude chemical thruster is enabled to perform satellite attitude control and adjustment; a second controller, configured to predict the unloading amount in advance in the second stage of orbit transfer, and perform momentum unloading according to the prediction result and the vector adjustment range, wherein in the first stage of orbit transfer, the electric thruster is enabled to change the satellite orbit; and a third controller, configured to shut down the momentum wheel in the third stage of orbit transfer to avoid the loss of momentum unloading, wherein in the third stage of orbit transfer, the on-board attitude chemical thruster is enabled to perform satellite attitude control and fixed-point capture control.

[0066] In one embodiment of the present invention, in the small geostationary orbit satellite orbit transfer method, the launch mass of the small geostationary orbit satellite is 2300 kg, and the small geostationary orbit satellite is carried and launched to a super-geosynchronous orbit, the apogee altitude of the super-geosynchronous orbit is 48,000 km, and the inclination of the super-geosynchronous orbit is 28.5 degrees; the launch point of the small geostationary orbit satellite is 101 degrees ± 0.05 degrees east longitude.

[0067] In one embodiment of the present invention, a small geostationary orbit satellite is transferred from an Earth transfer orbit to a geostationary orbit through three stages, including: a chemical thruster for orbit change is configured to ignite in the first stage to quickly raise the orbit perigee altitude to above a first altitude, and the domestic tracking and control arc is not less than a threshold tracking and control arc to perform orbit change for the control target; an electric thruster is configured to adjust the orbit perigee altitude to a second altitude in the second stage while adjusting the orbit inclination to a threshold inclination and the orbit eccentricity to a threshold eccentricity to perform orbit change for the control target; and an attitude control chemical thruster is configured to ignite in the third stage to enter the target orbit position accuracy range to perform fixed-point capture for the target.

[0068] In one embodiment of the present invention, in the small geostationary orbit satellite orbit transfer system, the rated thrust of the orbit change chemical thruster is 150N, and the number is 2; the rated thrust of the electric thruster is 300mN, and the number is 4, and the two electric thrusters are arranged side by side to form an electric thrust group, and the two electric thrust groups are distributed diagonally; the rated thrust of the attitude control chemical thruster is 10N, and the number is 4, and one orbit change chemical thruster and two attitude control chemical thrusters form a chemical thrust group, and the two chemical thrust groups are distributed diagonally.

[0069] The present invention proposes a method and system for transferring a small geostationary orbit satellite. The method and system utilize a hybrid propulsion combination of electric thrusters, orbit-changing chemical thrusters, and attitude control chemical thrusters configured for orbit transfer on a common platform for small high-orbit satellites. Combined with the energy characteristics of small geostationary orbit satellites and the space environment from Earth Transfer Orbit (GTO) to Geostationary Orbit (GEO), the orbit transfer process is divided into three stages for implementation. The method and system include: a first stage in which the orbit-changing chemical thrusters are used to rapidly increase the perigee altitude to above 8,000 km, with a domestic tracking and control arc duration of no less than 3 hours as a control target; a second stage in which the electric thrusters are used to simultaneously adjust the orbit altitude, inclination, and eccentricity as a control target, with the orbit perigee altitude adjusted to approximately 35,786 km and the orbit inclination and eccentricity adjusted to approximately 0 degrees; and a third stage in which the attitude control chemical thrusters are ignited to implement fixed-point capture with the target orbit position accuracy within the range.

[0070] The present invention is based on electric propulsion for orbit change, supplemented by a chemical propulsion system with hierarchical two-level backup for orbit change, wherein the first-level backup includes: in the first stage, the chemical orbit change thruster can back up the electric thruster; the second-level backup includes: in the third stage, the chemical attitude control thruster can back up the electric thruster. This means the hierarchical backup of the overall orbit change strategy. The present invention is mainly a method of momentum unloading, which is mainly reflected in: in the first stage, chemical orbit change thrusters are used for unloading; in the second stage, chemical attitude control thrusters or electric thrusters are selectively turned on for unloading according to the status; in the third stage, chemical orbit change thrusters are used for unloading. The advantage of this is that it reduces the need for the misalignment mechanism to constantly adjust the angle for unloading (because such adjustment not only affects the lifespan, but also the loss of orbit change thrust is relatively large), which has great benefits for the efficiency of the entire orbit change and the service life of the misalignment mechanism.

[0071] In summary, the above embodiments provide detailed descriptions of various configurations of spacecraft angular momentum control methods and systems. The present invention includes, but is not limited to, the configurations described in the above embodiments. Any modifications based on the configurations provided in the above embodiments fall within the scope of the present invention. Those skilled in the art can draw inferences based on the above embodiments.

[0072] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0073] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A method for controlling angular momentum of a spacecraft, characterized in that: include: During the first stage of orbit transfer, the momentum wheel is shut down to avoid the loss of momentum unloading. During the first stage of orbit transfer, the onboard attitude chemical thrusters are used to control and adjust the satellite attitude. During the first stage of orbit transfer, the orbit perigee altitude is raised to more than 8000km within 120 hours using the orbit transfer chemical thrusters, so that the satellite can escape from the Van Allen radiation belt. In the second stage of the orbit transfer, the unloading amount is predicted in advance, and momentum unloading is performed according to the predicted result and the vector adjustment range. In the first stage of the orbit transfer, the electric thrusters are used to perform satellite orbit change. In the second stage of the orbit transfer, the electric thrusters are used to perform orbit change with the goal of adjusting the orbit perigee altitude to 35,786 km and the orbit inclination and eccentricity to 0 degrees; and In the third stage of orbit transfer, the momentum wheel is turned off to avoid the loss of momentum unloading. In the third stage of orbit transfer, the on-board attitude chemical thrusters are used to perform satellite attitude control and fixed-point capture control to bring the satellite into the target orbit accuracy range.

2. The spacecraft angular momentum control method according to claim 1, wherein: Also includes: Transferring a small geostationary satellite from the Earth Transfer Orbit to the Geostationary Orbit through three orbit transfer stages, specifically: In the first stage of orbit transfer, the orbit change chemical thrusters are ignited to quickly raise the orbit perigee altitude to above the first altitude, and the domestic measurement and control arc is not less than the threshold measurement and control arc to execute the orbit change as the control target; In the second stage of the orbit transfer, the electric thrusters adjust the orbit perigee height to a second height, and at the same time, the orbit inclination is adjusted to a threshold inclination, and the orbit eccentricity is adjusted to a threshold eccentricity to perform the orbit transfer as a control target; and In the third stage of orbit transfer, the onboard attitude chemical thrusters are ignited to enter the target orbital position accuracy range and perform point capture for the target.

3. The spacecraft angular momentum control method according to claim 2, wherein: Also includes: The first altitude is 8000 km, the second altitude is 35786 km, the threshold measurement and control arc is 3 hours, the threshold inclination angle is 0 degrees, and the threshold eccentricity is 0 degrees; The first stage of the orbit transfer also includes the following steps: The orbit-changing chemical thruster raises the orbital perigee altitude of the small geostationary orbit satellite to above a first altitude within 120 hours; After the orbital perigee altitude of the small geostationary orbit satellite is raised to a first altitude, the orbit-changing chemical thruster is turned off.

4. The spacecraft angular momentum control method according to claim 2, wherein: The second stage of the orbit transfer also includes the following steps: Before the electric thruster performs the orbit change, a first orbit determination is performed to obtain the number of fine orbit elements of the second-stage initial orbit, the total mass of the satellite, and the center of mass, and the state of the electric thruster is set according to the result of the first orbit determination; After the control target of the second stage of the orbit transfer is achieved, shutting down the electric thruster; 1.5 hours before the electric thruster enters perigee, the electric thruster automatically shuts down, and the small geostationary orbit satellite automatically switches from the orbit change mode when the electric thruster is ignited to the earth holding mode; 1.5 hours after the electric thruster enters perigee, the small geostationary orbit satellite automatically switches from the ground-keeping mode to the orbit-changing and sun-facing mode when the electric thruster is ignited, and the electric thruster is automatically turned on and ignited for orbit change.

5. The spacecraft angular momentum control method according to claim 2, wherein: The third stage of the orbit transfer also includes the following steps: Before the onboard chemical attitude thrusters are ignited, a second orbit determination is performed to obtain the number of initial orbit elements, the satellite's total mass, and its center of mass for the third stage of orbit transfer, and the state of the onboard chemical attitude thrusters is set according to the results of the second orbit determination; After entering the target orbit accuracy range, the attitude chemical thruster is turned off and the working fluid flow of the orbit change chemical thruster is cut off to ensure the safety of the propulsion system after positioning.

6. The spacecraft angular momentum control method according to claim 4, wherein: The momentum unloading in the second stage of the orbit transfer is carried out at the orbit transfer perigee, and the momentum unloading in the second stage of the orbit transfer is carried out by electric thrusters or on-board attitude chemical thrusters; During the first and third stages of orbital transfer, the electric thrusters and momentum wheels are shut down, and satellite attitude control and adjustment are achieved only by relying on the on-board chemical thrusters.

7. The spacecraft angular momentum control method according to claim 6, wherein: Also includes: In the second stage of orbit transfer, when the electric thruster is changing its orbit, the ground will analyze the telemetry data transmitted from the satellite and predict the required unloading amount and the adjustment design angle range of the electric propulsion vector control mechanism, and decide whether to use the electric thruster or the onboard attitude chemical thruster to perform momentum unloading, so as to implement the unloading strategy 1 to 2 orbits in advance.

8. The spacecraft angular momentum control method according to claim 7, wherein: Also includes: In the second stage of orbit transfer, based on the lifespan and design adjustment angle range of the electric propulsion vector control mechanism, when both meet the requirements, the onboard attitude chemical thrusters or trajectory transfer chemical thrusters are shut down, the electric thrusters are turned on, and the electric thrusters are adjusted to perform momentum unloading. When the service life or adjustment design angle range is not met, on-board attitude chemical thrusters are used for momentum unloading.

9. The spacecraft angular momentum control method according to claim 8, wherein: According to the unloading strategy specified on the ground and the angular velocity telemetry on the satellite, the satellite independently judges and executes the unloading strategy 1.5 hours before entering the perigee, and completes the unloading and related safety operations within a total of 3 hours before and after the perigee. 1.5 hours after leaving the perigee, it autonomously enters the normal electric propulsion orbit change procedure.

10. A spacecraft angular momentum control system, characterized in that: include: The first controller is configured to shut down the momentum wheel during the first stage of orbit transfer to avoid momentum unloading losses, wherein during the first stage of orbit transfer, the onboard attitude chemical thrusters are used to control and adjust the satellite attitude, wherein during the first stage of orbit transfer, the orbit perigee altitude is raised to above 8000 km within 120 hours using the orbit transfer chemical thrusters, so that the satellite leaves the Van Allen radiation belt; The second controller is configured to predict the unloading amount in advance during the second stage of the orbit transfer, and perform momentum unloading according to the prediction result and the vector adjustment range, wherein in the first stage of the orbit transfer, the electric thruster is configured to perform the satellite orbit change, wherein in the second stage of the orbit transfer, the electric thruster is configured to perform the orbit change with the goal of adjusting the orbit perigee altitude to 35786 km and the orbit inclination and eccentricity to 0 degrees; as well as The third controller is configured to shut down the momentum wheel to avoid the loss of momentum unloading during the third stage of orbit transfer, wherein during the third stage of orbit transfer, the onboard attitude chemical thrusters are used to perform satellite attitude control and fixed-point capture control to bring the satellite into the target orbital position accuracy range.

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