Autonomous star observation method and system for ultra-low earth orbit satellites

Abstract

The application provides an autonomous star observation method for super low orbit satellites, comprising: setting a whole satellite mode word; judging whether an autonomous working condition trigger enable flag is enabled according to the whole satellite mode word; if yes, judging an orbit height decision working condition, and starting a star observation task according to the working condition; if no, setting a working condition through a ground instruction, and starting a star observation task according to the working condition. Meanwhile, an autonomous star observation system for super low orbit satellites is provided. The application can adapt to star observation task requirements under super low orbit height conditions, can overcome large aerodynamic interference moments under super low orbit conditions and large rotation moments caused by a turntable motor, can autonomously switch super low orbit star observation working conditions according to orbit heights, can reduce errors caused by ground orbit prediction, and can retain the ability of ground intervention whole satellite tasks, and can switch whole satellite autonomous observation and ground forced observation at any time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultra-low earth orbit satellites, in particular to an autonomous star observation method and system for ultra-low earth orbit satellites. BACKGROUND

[0002] In recent years, several countries and regions have begun to focus on the ultra-low earth orbit field and launch ultra-low earth orbit scientific exploration satellites. Ultra-low earth orbit satellites have advantages over other orbital height satellites in terms of improving optical imaging resolution, reducing transmission power, and reducing launch costs, but ultra-low earth orbit satellites also face stronger atmospheric resistance and more stringent thermal environments. To complete complex observation tasks under the harsh conditions of ultra-low earth orbit, it is necessary to fully coordinate the various modules of the satellite platform. The existing satellite platform for ultra-low earth orbit satellite observation tasks usually has the following technical problems:

[0003] 1. Unable to achieve autonomous observation, requiring ground operation and poor observation accuracy;

[0004] 2. Disturbed by aerodynamic environment, unable to achieve high-precision observation requirements under the condition of limited flywheel torque.

[0005] No similar technology to the present application has been found or reported, and no similar domestic or foreign data has been collected. SUMMARY

[0006] The present application provides an autonomous star observation method and system for ultra-low earth orbit satellites to guide ultra-low earth orbit satellites to achieve autonomous star observation tasks, aiming at the above-mentioned deficiencies in the prior art.

[0007] According to one aspect of the present application, an autonomous star observation method for ultra-low earth orbit satellites is provided, comprising:

[0008] Setting the whole satellite mode to the star observation mode and starting the star observation task; receiving the autonomous working condition trigger enable flag and the star sequence;

[0009] According to the star sequence, the observation behavior of the star observation task is obtained;

[0010] Determine whether the autonomous working condition trigger enable flag is enabled:

[0011] If enabled, autonomously determine the orbit height decision working condition, and start the star observation task according to the working condition;

[0012] If disabled, set the working condition through ground instructions, and start the star observation task according to the working condition;

[0013] Wherein, the working condition includes:

[0014] -260~230km working condition, corresponding to the first star observation task;

[0015] -220km working condition, corresponding to the second star observation task.

[0016] Preferably, the observation behavior of the star observation task is obtained according to the star sequence, including:

[0017] The ground sets the star mode as the star observation mode, and according to the star mode, a star sequence of each group of star observation tasks is obtained by using a star autonomous calculation method, the star sequence including position information, observation type, observation time length and observation relative time of the to-be-observed star;

[0018] Based on the observation type, the star sequence is divided into a calibration observation phase and a non-calibration observation phase, wherein the calibration observation phase contains a type of observation for device calibration, and the non-calibration observation phase contains a type of observation and a type of observation for actual observation;

[0019] The type of observation and the type of observation are self-defined according to the observation mode of the star;

[0020] In the calibration observation phase, multiple type of observations are continuously performed, and the number of observations is changed according to ground instructions;

[0021] In the non-calibration observation phase, type of observation and type of observation are performed at intervals.

[0022] Preferably, the autonomous working condition trigger enable flag includes a working condition flag word and an observation flag word; wherein:

[0023] The working condition flag word is used to distinguish different working conditions of the star observation task, and when the autonomous working condition trigger enable flag is enabled, the working condition flag word is autonomously triggered on the star according to the orbit height; when the autonomous working condition trigger enable flag is prohibited, the working condition flag word is set by the ground uplink instruction;

[0024] The observation flag word is used to determine the observation scheme of the first star observation task, and is set by the ground uplink instruction.

[0025] Preferably, the observation scheme of the first star observation task includes an observation scheme one and an observation scheme two; wherein:

[0026] The observation scheme one includes: during the type of observation, using a platform jet control to keep upright and a turntable tracking observation strategy; during the type of observation, using a platform wheel control tracking and a turntable positioning observation strategy; during the non-observation, using a platform jet control to keep upright and a turntable high-speed maneuvering strategy;

[0027] The second observation scheme comprises: during a first type of observation, using a strategy of sending a pre-guide pointing target star, platform wheel control keeping upright, and a turntable positioning; during a second type of observation, using a strategy of platform wheel control tracking, and a turntable positioning; during a non-observation, using a strategy of platform jet control keeping upright, and a turntable high-speed maneuvering.

[0028] Preferably, the second star observation task comprises:

[0029] During the observation process, a strategy of platform jet control and turntable tracking is used; during the non-observation, a strategy of platform jet control keeping upright and turntable high-speed maneuvering is used.

[0030] According to another aspect of the present application, there is provided an autonomous star observation system for a super-low-orbit satellite, comprising:

[0031] An instruction receiving module is configured to receive a whole-satellite mode word and an autonomous working condition triggering enable flag;

[0032] A star sequence receiving module is configured to receive a star sequence transmitted by a load, and transmit the star sequence to a task setting module;

[0033] The task setting module is configured to obtain an observation behavior of a star observation task according to the star sequence, and transmit the obtained observation behavior to a guide module;

[0034] A task starting module is configured to determine whether the autonomous working condition triggering enable flag is enabled: if enabled, determine an orbit height decision working condition, and start the star observation task according to the working condition; if disabled, set a working condition through a ground instruction, and start the star observation task according to the working condition;

[0035] A guide law module is configured to calculate platform guidance and turntable guidance.

[0036] According to a third aspect of the present application, there is provided a computer terminal comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, is configured to execute the method according to any one of the above aspects of the present application, or run the system according to any one of the above aspects of the present application.

[0037] According to a fourth aspect of the present application, there is provided a computer readable storage medium having a computer program stored thereon, wherein the program, when executed by a processor, is configured to execute the method according to any one of the above aspects of the present application, or run the system according to any one of the above aspects of the present application.

[0038] Compared with the prior art, the present application has at least one of the following beneficial effects:

[0039] The application provides an autonomous star observation method and system for super low orbit satellites.

[0040] The autonomous star observation method and system for super low orbit satellites can adapt to star observation task requirements under super low orbit height conditions, and can overcome large aerodynamic interference moments under super low orbit conditions and large rotation moments caused by the rotation of a turntable.

[0041] The autonomous star observation method and system for super low orbit satellites can subdivide observation tasks into two under the condition that observation accuracy requirements remain unchanged, namely super low orbit star observation one with an orbit height of 260-230 km and super low orbit star observation two with an orbit height of 220 km, and different observation schemes are designed for the two tasks, and the observation accuracy requirements can be met.

[0042] The autonomous star observation method and system for super low orbit satellites can automatically switch super low orbit star observation working conditions according to orbit heights, and reduces errors caused by ground orbit prediction.

[0043] The autonomous star observation method and system for super low orbit satellites can retain the ability of ground intervention star task, and can switch star autonomous observation and ground forced observation at any time. BRIEF DESCRIPTION OF DRAWINGS

[0044] Other features, objects and advantages of the application will become more apparent from the following detailed description of non-limiting embodiments with reference to the attached drawings:

[0045] Figure 1 The figure is a work flow chart of the autonomous star observation method for super low orbit satellites in a preferred embodiment of the application.

[0046] Figure 2 The figure is a working principle diagram of the autonomous star observation method for super low orbit satellites in a specific application example of the application.

[0047] Figure 3 The figure is a typical time sequence diagram of a star observation scheme one for super low orbit satellites with an orbit height of 260-230 km in a specific application example of the application, and the number of calibration stars is M=3.

[0048] Figure 4 The figure is a typical time sequence diagram of a star observation scheme two for super low orbit satellites with an orbit height of 260-230 km in a specific application example of the application, and the number of calibration stars is M=3.

[0049] Figure 5For a specific application example of the present application, a 220km ultra-low orbit star observation guiding law typical time sequence diagram is shown, and the number of calibration stars M=3.

[0050] Figure 6 For a specific application example of the present application, a star observation time interval schematic diagram is shown.

[0051] Figure 7 For a preferred embodiment of the present application, a schematic diagram of the composition module of the autonomous star observation system for ultra-low orbit satellites is shown. DETAILED DESCRIPTION

[0052] The embodiments of the present application are described in detail below: the embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given. It should be noted that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application.

[0053] An embodiment of the present application provides an autonomous star observation method for ultra-low orbit satellites, as shown in the figure, which can include: Figure 1

[0054] Setting the whole star mode in the star observation mode, starting the star observation task; receiving the autonomous working condition trigger enable flag and the star sequence;

[0055] According to the star sequence, the observation behavior of the star observation task is obtained;

[0056] Judging whether the autonomous working condition trigger enable flag is enabled:

[0057] If enabled, the orbit height determines the working condition, and according to the working condition, the star observation task is started;

[0058] If disabled, the working condition is set through the ground instruction, and according to the working condition, the star observation task is started;

[0059] Wherein: the working condition includes:

[0060] -260~230km working condition, corresponding to star observation task one;

[0061] -220km working condition, corresponding to star observation task two.

[0062] In a preferred embodiment, according to the star sequence, the observation behavior of the star observation task includes:

[0063] ​The ground sets the whole star mode as a star observation mode. According to the whole star mode, a star sequence (as shown in Table A) of each group of star observation tasks is obtained by using a star autonomous calculation method, and the star sequence includes position information of a to-be-observed star, an observation type, an observation time length, and an observation relative time.

[0064] Based on the observation type, the star sequence is divided into a calibration observation stage and a non-calibration observation stage. The calibration observation stage contains a type of observation, which is used for device calibration. The non-calibration observation stage contains a type of observation and a type II observation, which are used for actual observation.

[0065] The type I observation type and the type II observation type are self-defined classifications according to the observation mode of the star.

[0066] In the calibration observation stage, multiple type I observations are continuously performed, and the number of observations is changed according to ground instructions.

[0067] In the non-calibration observation stage, type I observations and type II observations are performed at intervals.

[0068] Table A Star Sequence

[0069]

[0070]

[0071] In a preferred embodiment, the autonomous working condition trigger enabling flag includes a working condition flag word and an observation flag word. Wherein:

[0072] The working condition flag word is used to distinguish different working conditions of the star observation task. When the autonomous working condition trigger enabling flag is enabled, the working condition flag word is autonomously triggered on the star according to the orbit height. When the autonomous working condition trigger enabling flag is prohibited, the working condition flag word is set by the ground uplink instruction.

[0073] The observation flag word is used to determine the observation scheme of the star observation task I, which is set by the ground uplink instruction.

[0074] In a preferred embodiment, the observation scheme of the star observation task I includes an observation scheme I and an observation scheme II. Wherein:

[0075] The observation scheme I includes: during the type I observation, using a platform jet control to keep upright and a turntable tracking observation strategy; during the type II observation, using a platform wheel control tracking and a turntable positioning observation strategy; and during the non-observation, using a platform jet control to keep upright and a turntable high-speed maneuvering strategy.

[0076] Further, the first scheme is specifically: the ground sets the whole star mode as the star observation mode, and the platform guidance is switched from the side-lying non-bias flow state to the vertical non-bias flow state at the time when the whole star mode is set; the platform is cut to the vertical state for a period of time, and then the turntable is started to prepare for the subsequent observation; after the star observation mode enters a fixed time length, the load calculates the star sequence, and the star sequence is sent to the task guidance module; the task guidance module calculates the platform guidance and the turntable guidance according to the obtained star sequence. The specific guidance is related to the observation type, the platform jet control keeps vertical during the first type of star observation, and the turntable tracks; the platform wheel control tracks during the second type of star observation, and the turntable positions. The platform jet control keeps vertical during the non-observation period, and the turntable high-speed maneuvers.

[0077] The second observation scheme includes: during the first type of observation, the observation strategy of sending the pre-guidance pointing to the target star, the platform wheel control keeping vertical, and the turntable positioning is adopted; during the second type of observation, the observation strategy of the platform wheel control tracking and the turntable positioning is adopted; during the non-observation period, the strategy of the platform jet control keeping vertical and the turntable high-speed maneuvering is adopted.

[0078] Further, the second scheme is specifically: the ground sets the whole star mode as the star observation mode, and the platform guidance is switched from the side-lying non-bias flow state to the vertical non-bias flow state at the time when the whole star mode is set; the platform is cut to the vertical state for a period of time, and then the turntable is started to prepare for the subsequent observation; after the star observation mode enters a fixed time length, the load calculates the star sequence, and the star sequence is sent to the task guidance module; the task guidance module calculates the platform guidance and the turntable guidance according to the obtained star sequence. The specific guidance is related to the observation type, the platform wheel control keeps vertical during the first type of star observation, and the turntable tracks; the platform wheel control tracks during the second type of star observation, and the turntable positions. The platform jet control keeps vertical during the non-observation period, and the turntable high-speed maneuvers.

[0079] In a preferred embodiment, the second star observation task includes:

[0080] The observation process adopts the observation strategy of the platform jet control and the turntable tracking; during the non-observation period, the strategy of the platform jet control keeping vertical and the turntable high-speed maneuvering is adopted.

[0081] Further, the second task is specifically: the ground sets the whole star mode as the star observation mode, and the platform guidance is switched from the side-lying non-bias flow state to the vertical non-bias flow state at the time when the whole star mode is set; the platform is cut to the vertical state for a period of time, and then the turntable is started to prepare for the subsequent observation; after the star observation mode enters a fixed time length, the load calculates the star sequence, and the star sequence is sent to the task guidance module; the task guidance module calculates the platform guidance and the turntable guidance according to the obtained star sequence. The specific guidance is: the observation process adopts the observation strategy of the platform jet control and the turntable tracking; during the non-observation period, the platform jet control keeps vertical, and the turntable high-speed maneuvers.

[0082] The technical solution provided by the above embodiments of the present invention will be further described in detail below with reference to a specific application example.

[0083] A typical process for observing stars in very low Earth orbit involves multiple stars, which can be divided into two categories based on the observation method: Type I stars and Type II stars.

[0084] like Figure 2 As shown, ultra-low orbit star observations can be performed in multiple sessions at each orbital altitude. Each session is defined as a group. At 260–230 km, each group lasts about 17 minutes, and at 220 km, each group lasts about 12 minutes.

[0085] The stellar sequence observed by each mission (provided by the user) is calculated autonomously by the satellite and can be divided into two observation phases: calibration and non-calibration. During the calibration phase, multiple Type I stars will be observed continuously, with a default of 3 stars. During the non-calibration phase, Type I stars will be observed continuously in the order of Type II stars.

[0086] In this specific application example, the functional requirements to be implemented include:

[0087] Ultra-low Earth Orbit (ULE) stellar observations can be subdivided into two missions based on orbital altitude: ULE 1 operates at an altitude of 260km–230km, while ULE 2 operates at an altitude of 220km. During mission initiation, the onboard software checks for a ground-based uplink mission sequence at each 4Hz (every 250ms) cycle. If this sequence includes the ULE stellar observation whole-satellite mode word, the entire satellite enters the corresponding mode and performs observations based on the stellar sequence sent by the payloads. The mission initiation process autonomously determines the platform and turntable operating modes and issues guidance laws to coordinate the turntable, platform, and payloads in executing the ULE stellar observation mission. Specific mission modes are shown in Table 1.

[0088] Table 1. Mission status and observation plan for ultra-low Earth orbit star observation missions

[0089]

[0090] The conditions for triggering different operational states in ultra-low orbit (ULE) star observations are the "operational state flag" and the "observation flag." The "operational state flag" distinguishes different operational states for the ULE star observation mission. When the "autonomous triggering operational state enable flag" is "enabled," this flag is autonomously triggered by the satellite based on its orbital altitude. When the "autonomous triggering operational state enable flag" is "disabled," this flag is set by ground uplink commands. The "autonomous triggering operational state enable flag" is enabled by default. The "observation flag" determines the observation plan for ULE star observation mission one and is set by ground uplink commands.

[0091] I. Ultra-low Earth Orbit Star Observation Mission 1

[0092] The super low orbit star observation task must be triggered when the whole star mode is "super low orbit star observation".

[0093] The forms of several turntable guide laws used are shown in Tables 2-4.

[0094] Table 2 Turntable guide law - high-speed maneuver

[0095] Mode word Time (sec) Time millisecond value Target azimuth angle (rad) Target elevation angle (rad) High speed maneuver 0 0 Ae j1 ]]> El j1 ]]

[0096] Table 3 Turntable guide law - positioning

[0097] Mode word Time (sec) Time millisecond value Target azimuth angle (rad) Target elevation angle (rad) Positioning 0 0 Ae j1 ]] El j1 ]]

[0098] Table 4 Turntable guide law - low-speed maneuver (direction reset after the last observation ends)

[0099] Mode word Time (sec) Time millisecond value Target azimuth angle Target elevation angle Low speed maneuver 0 0 π 0

[0100] Note: The turntable maneuver is divided into high-speed maneuver and low-speed maneuver according to the upper limit of the angular velocity and angular acceleration. The angular velocity and angular acceleration are greater during high-speed maneuver, for example: the upper limit of the angular velocity and angular acceleration during high-speed maneuver is 16° / s and 10° / s 2 , and the upper limit of the angular velocity and angular acceleration during low-speed maneuver is 8° / s and 2° / s 2 , and the turntable can reach the specified angle faster.

[0101] When the turntable is tracking, the azimuth angle and elevation angle are calculated in real time according to the target position, and the maneuver is performed according to the threshold of high-speed maneuver.

[0102] 1.1 Scheme one (turntable tracking as the main), including: during the observation of the first type, the platform jet control keeps upright, and the turntable tracks; during the observation of the second type, the platform wheel control tracks, and the turntable positions. During the non-observation period, the platform jet control keeps upright, and the turntable high-speed maneuvers.

[0103] The typical time sequence diagram of the super low orbit star observation scheme one guide law for 260-230km super low orbit is shown in Figure 3 .

[0104] The state of the attitude control control flag during the star observation stage of the super low orbit star observation scheme one for 260-230km super low orbit is shown in Table 5.

[0105] Table 5 State of attitude control control flag during star observation stage of super low orbit star observation scheme one for 260-230km super low orbit

[0106]

[0107] Wherein, under the premise of the whole star mode is "super low orbit star observation task", if in other period, the star observation stage and the attitude control control sign show "invalid".

[0108] Taking 9 stars as an example, the typical process is shown in Table 6.

[0109] Table 6 Scheme one (class one observation turntable tracking) typical process

[0110]

[0111]

[0112] Wherein, T0 is the task starting time, the first task T0 is the whole star mode execution time of "super low orbit star observation task", and the subsequent task is autonomously started with Tjg interval. T_start is the time reference (UTC cumulative whole second value) in the star sequence, Tj 1 is the interval time of the jth star observation relative to T_start, detTj is the observation time of the jth star, MDT is the timeout protection, and the protection time of the super low orbit star observation task is 17 min.

[0113] 1.2 Scheme two (platform wheel control is mainly included): during class one observation, send the advance guide to the target star, the platform wheel control keeps upright, and the turntable is positioned; during class two observation, the platform wheel control tracks, and the turntable is positioned; during non-observation, the platform jet control keeps upright, and the turntable is high-speed maneuvered.

[0114] The typical time sequence diagram of the super low orbit star observation scheme two guide law of 260-230 km is shown in Table 7. Figure 4

[0115] The state of the star observation stage and the attitude control control sign of the super low orbit star observation scheme two of 260-230 km is shown in Table 7.

[0116] Table 7 The state of the star observation stage and the attitude control control sign of the super low orbit star observation scheme two of 260-230 km

[0117]

[0118] Wherein, under the premise of the whole star mode is "super low orbit star observation task", if in other period, the star observation stage and the attitude control control sign show "invalid".

[0119] Taking 9 stars as an example, the typical process is shown in Table 8.

[0120] Table 8 Scheme two (class one observation platform wheel control) typical process

[0121] ​

[0122]

[0123]

[0124] II. The second ultra-low earth orbit star observation mission, including the observation scheme of the second ultra-low earth orbit star observation, is an observation strategy of platform jet control during the whole observation process and high-speed maneuvering of the turntable during non-observation.

[0125] When the mission and guidance law module receives the uplink mission sequence from the ground (the whole star mode word of the ultra-low earth orbit star observation is included in this planning), the observation mission is performed according to the star sequence issued by the load, the software autonomously judges the working mode of the platform and the turntable, issues the guidance law, and makes the turntable, each load and the platform cooperate to execute the ultra-low earth orbit star observation mission.

[0126] A typical timing diagram of the guidance law of the second ultra-low earth orbit star observation mission at 220 km is shown in FIG. 9. Figure 5

[0127] The state of the star observation phase and the attitude control control flag of the second ultra-low earth orbit star observation mission at 220 km is shown in Table 9.

[0128] Table 9 State of star observation phase and attitude control control flag of 220 km ultra-low earth orbit star observation

[0129]

[0130] Under the premise of the whole star mode being "ultra-low earth orbit star observation mission", if it is in other time periods, the star observation phase and the attitude control control flag are displayed as "invalid".

[0131] Taking 9 stars as an example, a typical process is shown in Table 10.

[0132] MDT is an overtime protection, and the protection time length of the second ultra-low earth orbit star observation mission is 12 min.

[0133] Table 10 Typical process of the second ultra-low earth orbit star observation mission

[0134]

[0135]

[0136] In this specific application example, the star observation timing constraints to be achieved include:

[0137] ​When the ultra-low earth orbit star observation autonomous calculates the star sequence, the related time interval constraints need to be considered, the platform and the turntable are reserved enough time for the motor, and the platform stability and the pointing accuracy are ensured to meet the observation requirements. The specific constraints are related to the working condition setting and the observation scheme. For a class of star observation, the platform and the turntable motor time reserved is△t1, and the observation time length is△t2. For the second class of star observation, the platform and the turntable motor time reserved is△t3+△t4, and the observation time length is△t5. As shown in Figure 6 .

[0138] Figure 5 Middle:△t1 for the "first calibration star" is [the turntable start time + 50s, the first calibration star observation start time];△t2 corresponds to the "star observation time length" of a class of stars;△t5 corresponds to the "star observation time length" of the second class of stars.

[0139] If△t2 is a calibration star observation, the satellite platform is required to be oriented to the ground, and the turntable is positioned at the angular position of the corresponding star in the spacecraft body coordinate system at the observation middle time. In different orbit altitudes and attitude control modes, the related time interval constraints are different, and the related constraints are given in turn as follows.

[0140] I. 260km-230km observation requirements

[0141] 260km-230km vertical observation for 17min, including 2min calibration + 15min observation.

[0142] Scheme one: a class of observation adopts the turntable tracking

[0143] A class of observation and calibration star observation time period are all adopted platform jet control + turntable tracking, and the platform wheel control and the turntable positioning are adopted in the second class of observation time period. The specific time allocation is as follows:

[0144]

[0145] Note: dAA is the azimuth angle difference of adjacent two star observations. The time length of each stage mainly depends on the platform and the turntable motor ability.

[0146] Scheme two: a class of observation adopts platform wheel control

[0147] A class of observation, the second class of observation and calibration star observation time period are all adopted platform wheel control. The specific time allocation is as follows:

[0148]

[0149] Note: dAA is the azimuth angle difference of adjacent two star observations. The time length of each stage mainly depends on the platform and the turntable motor ability.

[0150] II. 220km observation requirements

[0151] 220km erect observation 12min, including 2min calibration + 10min observation. The specific time allocation is as follows:

[0152]

[0153] Note: dEE is the angle difference between the elevation angles of two adjacent star observations. The duration of each stage mainly depends on the platform and the slewing ability of the turntable.

[0154] When autonomously calculating the star sequence for super low orbit star observation, other constraints also need to be considered.

[0155] The interval duration between two adjacent super low orbit star observation procedures needs to be greater than Tjg, and Tjg is 1h by default, which can be modified by ground uplink instructions.

[0156] An embodiment of the present application provides an autonomous star observation system for a super low orbit satellite, as shown in the figure, the system can comprise: Figure 7 An instruction receiving module, which is used for receiving a star mode word and an autonomous working condition trigger enable flag.

[0157] A star sequence receiving module, which is used for receiving a star sequence transmitted by a payload and transmitting the star sequence to a task setting module.

[0158] A task setting module, which is used for obtaining an observation behavior of a star observation task according to the star sequence and transmitting the obtained observation behavior to a guide module.

[0159] A task starting module, which is used for judging whether the autonomous working condition trigger enable flag is enabled: if yes, judging an orbit height determined working condition and starting the star observation task according to the working condition; if no, setting the working condition through a ground instruction and starting the star observation task according to the working condition.

[0160] A guide law module, which is used for calculating platform guidance and turntable guidance.

[0161] It should be noted that the steps in the method provided by the present application can be realized by corresponding modules, devices, units, etc. in the system, and those skilled in the art can refer to the technical solution of the method to realize the composition of the system, that is, the embodiments in the method can be understood as preferred examples of constructing the system, which will not be described here.

[0162]

[0163] ​An embodiment of the present application provides a computer terminal, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor is configured to execute the computer program to implement the method of any one of the above-mentioned embodiments of the present application or run the system of any one of the above-mentioned embodiments of the present application.

[0164] Optionally, the memory is configured to store the program, and the memory can comprise volatile memory, such as random-access memory (RAM), for example, static random-access memory (SRAM), Double Data Rate Synchronous Dynamic Random Access Memory (DDR SDRAM) and the like, or non-volatile memory, such as flash memory. The memory is configured to store computer programs (such as application programs, functional modules and the like for implementing the above-mentioned method), computer instructions and the like, and the above-mentioned computer programs, computer instructions and the like can be stored in one or more memories in a partitioned manner. Furthermore, the above-mentioned computer programs, computer instructions and data can be invoked by the processor.

[0165] The above-mentioned computer programs, computer instructions and the like can be stored in one or more memories in a partitioned manner. Furthermore, the above-mentioned computer programs, computer instructions and data can be invoked by the processor.

[0166] The processor is configured to execute the computer program stored in the memory to implement each step in the method or each module of the system according to the above-mentioned embodiments. Details can be referred to the related description in the above-mentioned method and system embodiments.

[0167] The processor and the memory can be an integrated structure or an independent structure. When the processor and the memory are an independent structure, the memory and the processor can be coupled and connected through a bus.

[0168] An embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the program is executable by the processor to implement the method of any one of the above-mentioned embodiments of the present application or run the system of any one of the above-mentioned embodiments of the present application.

[0169] The autonomous star observation method and system for ultra-low earth orbit satellites provided by the above embodiments of the present application adapt to the star observation task requirements under the ultra-low orbit height condition, can overcome the problem of large aerodynamic interference torque under the ultra-low orbit condition and the large rotation torque caused by the rotation table maneuvering, and can meet the observation accuracy requirements under the condition that the observation accuracy requirements remain unchanged. The observation task is subdivided into two according to the orbit height condition, namely, ultra-low orbit star observation one with an orbit height of 260-230 km and ultra-low orbit star observation two with an orbit height of 220 km. Different observation schemes are designed for the two tasks, and both can meet the observation accuracy requirements. The ultra-low orbit star observation working condition can be autonomously switched according to the orbit height, and the error caused by the ground orbit prediction is reduced. The ground intervention star task capability is retained, and the star autonomous observation and ground forced observation can be switched at any time.

[0170] Those skilled in the art know that, in addition to implementing the system and each device thereof provided by the present application in the form of pure computer readable program code, the system and each device thereof provided by the present application can also be implemented in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers and embedded microcontrollers, etc. by logically programming the method steps to achieve the same functions. Therefore, the system and each device thereof provided by the present application can be considered as a hardware component, and the devices included therein for achieving various functions can also be considered as structures in the hardware component. The devices for achieving various functions can also be considered as both software modules for implementing methods and structures in the hardware component.

[0171] The details not described in the above embodiments of the present application are known in the art.

[0172] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the above specific embodiments, and various modifications or changes can be made by those skilled in the art within the scope of the claims, which does not affect the essential content of the present application.

Claims

1. An autonomous star observation method for ultra-low earth orbit satellites, characterized in that, include: Set the entire star mode to star observation mode and start the star observation mission; Receive autonomous operating condition trigger enable flag and star sequence; Based on the stellar sequence, the observation behavior of the stellar observation mission is obtained; Determine if the autonomous operating condition trigger enable flag is enabled: If enabled, it will autonomously determine the orbital altitude to determine the operating conditions and start the star observation mission based on the operating conditions; If prohibited, the operating conditions are set via ground commands, and the star observation mission begins according to the operating conditions. Wherein: the operating conditions include: - Operating conditions of 260~230km, corresponding to the first stellar observation mission; - 220km operating conditions, corresponding to the second stellar observation mission; The observation scheme for the first stellar observation mission includes: Observation Scheme 1 and Observation Scheme 2; wherein: The first observation scheme includes: during the first type of observation, an observation strategy is adopted to keep the platform upright by jet control and to track the turntable; during the second type of observation, an observation strategy is adopted to track the platform by wheel control and to position the turntable; and during the non-observation period, a strategy is adopted to keep the platform upright by jet control and to maneuver the turntable at high speed. The second observation scheme includes: during the first type of observation, an observation strategy is adopted in which the platform sends a pre-guided signal to the target star, maintains its upright position using platform wheel control, and positions the turntable; during the second type of observation, an observation strategy is adopted in which the platform wheel control tracks and positions the turntable; and during non-observation periods, a strategy is adopted in which the platform uses jet control to maintain its upright position and the turntable maneuvers at high speed. The second stellar observation mission includes: During the observation process, a platform jet control and turntable tracking strategy were adopted; during non-observation periods, a platform jet control strategy was adopted to keep the platform upright and a turntable for high-speed maneuvering was adopted.

2. The autonomous star observation method for ultra-low earth orbit satellites according to claim 1, characterized in that, The observation activities of the stellar observation mission, based on the stellar sequence, include: The ground-based system is set to a whole-satellite observation mode. Based on this whole-satellite mode, the star sequence for each star observation mission is obtained using an onboard autonomous calculation method. The star sequence includes: the position information of the star to be observed, the observation type, the observation duration, and the relative observation time. Based on the observation type, the star sequence is divided into a calibration observation stage and an uncalibrated observation stage. The calibration observation stage includes a type I observation for equipment calibration, and the uncalibrated observation stage includes a type I observation and a type II observation for actual observation. The first type of observation and the second type of observation are customized according to the observation method of the stars; During the calibration observation phase, multiple Class I observations are conducted consecutively, and the number of observations can be changed according to ground commands. During the non-calibration observation phase, Class I and Class II observations are conducted alternately.

3. The method for autonomous star observation for ultra-low Earth orbit satellites of claim 1, wherein, The autonomous operating condition trigger enable flag includes: an operating condition flag word and an observation flag word; wherein: The operational status flag is used to distinguish different operational statuses of the stellar observation mission. When the autonomous trigger operational status enable flag is enabled, the operational status flag is autonomously triggered by the satellite based on the orbital altitude. When the autonomous trigger operational status enable flag is disabled, the operational status flag is set by uplink commands from the ground. The observation flag is used to determine the observation scheme for the first stellar observation mission and is set by ground uplink commands.

4. An observation system using the autonomous star observation method for ultra-low earth orbit satellites according to claim 1, characterized by, include: An instruction receiving module, configured to receive a whole-satellite mode word and an autonomous working condition trigger enable flag on the ground; A constant star sequence receiving module, configured to receive a constant star sequence transmitted by a payload, and transmit the constant star sequence to a task setting module; The task setting module is configured to obtain an observation behavior of a constant star observation task according to the constant star sequence, and transmit the obtained observation behavior to a guiding module; A task starting module, configured to judge whether the autonomous working condition trigger enable flag is enabled: if yes, judge an orbit height decision working condition, and start the constant star observation task according to the working condition; if no, set the working condition through the ground instruction, and start the constant star observation task according to the working condition; A guiding law module, configured to calculate platform guiding and turntable guiding.

5. A computer terminal comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the program, and can be used for executing the method in any one of claims 1-3, or running the system in claim 4.

6. A computer-readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor, and can be used for executing the method in any one of claims 1-3, or running the system in claim 4.

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