A method and device for selecting satellites for a low-orbit ultra-large-scale hybrid constellation

Abstract

The present invention relates to the field of constellation star selection, and specifically discloses a method and device for selecting stars for a low-orbit ultra-large-scale hybrid constellation. It includes constructing a medium-orbit navigation constellation to perform failure performance analysis, determine the failure mode of the satellite with the greatest impact, and use the deployed low-orbit satellite constellation for navigation enhancement, analyze the configuration of the low-orbit ultra-large-scale constellation, determine the single-star selection navigation enhancement scheme and the orbital plane selection navigation enhancement scheme, construct an objective function and a fitness function, and use the NSGA-II algorithm, the objective function and the fitness function to optimize the above two schemes to obtain the optimization results of the two navigation enhancement schemes, compare the optimization results of the two navigation enhancement schemes with the performance of the reference navigation constellation, and determine the optimal solution. It aims to quickly make up for the shortcomings of performance degradation after the failure of the medium-orbit constellation satellite, and at the same time, there is no need to establish a corresponding navigation enhancement constellation, thereby reducing costs and improving the overall satellite service performance of the constellation.

Description

Technical Field

[0001] The present invention relates to the field of satellite constellation selection, and in particular to a low-orbit ultra-large-scale hybrid constellation selection method and device. Background Art

[0002] As space powers gradually deploy and plan low-orbit ultra-large-scale constellations, the number of low-orbit satellites operating in space has exploded. For low-orbit ultra-large-scale constellations, serving a certain field alone makes a large number of satellites redundant. If satellites carry different integrated payloads, they can be used to handle different tasks, such as emergency rescue, disaster warning, ground mapping, meteorological and ocean observation, and improving the positioning accuracy of marine and aviation navigation.

[0003] The four major global satellite navigation systems are becoming increasingly important in bringing social and economic benefits to the world. Compared with the rapidly changing geometric configuration and low transmission delay of low-orbit satellites, it takes a long time for the precise single-point positioning of medium- and high-orbit navigation satellites to converge to centimeter-level positioning accuracy. Medium-orbit satellites are inevitably prone to failures when operating in harsh space environments, and the cost of satellite construction and launch is expensive. Therefore, it is necessary to avoid the performance degradation of medium-orbit constellation satellites after failure to ensure the normal operation of functions. Summary of the invention

[0004] In view of the above problems, an object of the present invention is to provide a method for selecting satellites for a low-orbit ultra-large-scale hybrid constellation.

[0005] The second object of the present invention is to provide a low-orbit ultra-large-scale hybrid constellation star selection device.

[0006] The first technical solution adopted by the present invention is:

[0007] S1. Build a medium-orbit navigation constellation to conduct failure performance analysis, determine the satellite failure mode with the greatest impact, and use the deployed low-orbit satellite constellation for navigation enhancement;

[0008] S2. Analyze the configuration of the ultra-large-scale low-orbit constellation and determine the navigation enhancement scheme for selecting a single satellite and the navigation enhancement scheme for the orbital plane;

[0009] S3, constructing an objective function and a fitness function, and optimizing the single-star selection navigation enhancement scheme and the orbital plane selection navigation enhancement scheme respectively by using the NSGA-II algorithm, the objective function and the fitness function, to obtain optimization results of the two navigation enhancement schemes;

[0010] S4. Compare the optimization results of the two navigation enhancement schemes with the performance of the reference navigation constellation to determine the optimal scheme.

[0011] Optionally, the single-star selection navigation enhancement solution includes:

[0012] S31. Perform simulation and satellite transit time screening based on the simulation parameters of the Starlink low-orbit large-scale constellation to obtain the screened satellites;

[0013] S32, using the NSGA-II algorithm to select the screened satellites and determine the selected satellite data;

[0014] S33, based on the star selection data, optimizing using the objective function and constraint conditions;

[0015] S34, introducing an optimization evaluation index, and selecting a unique optimal solution through the fitness function.

[0016] Optional, orbital plane selection navigation enhancement solutions include:

[0017] S35. Perform simulation based on the simulation parameters of the Starlink low-orbit large-scale constellation to determine the constellation orbital plane;

[0018] S36, selecting the constellation orbital plane using the NSGA-II algorithm to obtain an optimized parameter set;

[0019] S37, performing optimization using the objective function and the constraint conditions according to the optimization parameter set;

[0020] S38, introducing the optimization evaluation index, and selecting a unique optimal solution through the fitness function.

[0021] Optionally, the objective function is as follows:

[0022]

[0023] Where Total is the maximum value of the number of visible satellites, and PDOP is the position precision factor;

[0024] The constraint condition is as follows:

[0025]

[0026] In the formula It is the minimum PDOP of the hybrid constellation formed by the low orbit after the failure of the middle orbit between the north and south latitudes m°~n°, and Q is the threshold, which is a constant.

[0027] Optionally, the fitness function is as follows:

[0028]

[0029] Where f1(X) is the PDOP value of the satellite selection scheme X, f2(X) is the total number of satellites selected for the navigation augmentation constellation of the satellite selection scheme X, and V maxis the maximum PDOP of the star selection scheme in the Pareto solution set, E max Select the maximum number of satellites for the navigation augmentation constellation, V min is the minimum PDOP value of the star selection scheme in the Pareto solution set, E min Select the minimum total number of satellites for the navigation augmentation constellation.

[0030] The second technical solution adopted by the present invention is:

[0031] Failure analysis module, used to build a medium-orbit navigation constellation for failure performance analysis, determine the most influential satellite failure mode, and use the deployed low-orbit satellite constellation for navigation enhancement;

[0032] The scheme determination module is used to analyze the configuration of the ultra-large-scale low-orbit constellation and determine the navigation enhancement scheme for selecting a single satellite and the navigation enhancement scheme for selecting the orbital plane;

[0033] An optimization module is used to construct an objective function and a fitness function, and optimize the single-star selection navigation enhancement scheme and the orbital plane selection navigation enhancement scheme respectively by using the NSGA-II algorithm, the objective function and the fitness function to obtain optimization results of the two navigation enhancement schemes;

[0034] The optimal module is used to compare the optimization results of the two navigation enhancement schemes with the performance of the reference navigation constellation to determine the optimal scheme.

[0035] Optionally, the single-star selection navigation enhancement solution includes:

[0036] The screening submodule is used to perform simulation and satellite transit time screening based on the simulation parameters of the Starlink low-orbit large-scale constellation to obtain the screened satellites;

[0037] A satellite selection submodule is used to select the selected satellites using the NSGA-II algorithm and determine the satellite selection data;

[0038] A first optimization submodule, configured to perform optimization based on the star selection data using the objective function and constraint conditions;

[0039] The first optimal selection module is used to introduce an optimization evaluation index and select a unique optimal solution through the fitness function.

[0040] Optional, orbital plane selection navigation enhancement solutions include:

[0041] The orbital plane determination module is used to perform simulation based on the simulation parameters of the Starlink low-orbit large-scale constellation and determine the constellation orbital plane;

[0042] An orbital plane selection module, used to select the orbital plane of the constellation using the NSGA-III algorithm to obtain an optimized parameter set;

[0043] A second optimization submodule, configured to perform optimization using the objective function and the constraint conditions according to the optimization parameter set;

[0044] The second optimal selection module is used to introduce the optimization evaluation index and select a unique optimal solution through the fitness function.

[0045] Optionally, the objective function is as follows:

[0046]

[0047] In the formula, Total is the maximum value of the number of visible satellites;

[0048] The constraint condition is as follows:

[0049]

[0050] In the formula It is the minimum PDOP of the hybrid constellation formed by the low orbit after the failure of the middle orbit between the north and south latitudes m°~n°, and Q is the threshold, which is a constant.

[0051] Optionally, the fitness function is as follows:

[0052]

[0053] Where f1(X) is the PDOP value of the satellite selection scheme X, f2(X) is the total number of satellites selected for the navigation augmentation constellation of the satellite selection scheme X, and V max is the maximum PDOP of the star selection scheme in the Pareto solution set, E max Select the maximum number of satellites for the navigation augmentation constellation, V min is the minimum PDOP value of the star selection scheme in the Pareto solution set, E min Select the minimum total number of satellites for the navigation augmentation constellation.

[0054] Beneficial effects of the above technical solution:

[0055] The present invention uses the existing deployed low-orbit ultra-large-scale constellation to perform navigation enhancement constellation satellite selection, which can quickly make up for the performance degradation of the medium-orbit constellation satellite after failure. At the same time, there is no need to establish a corresponding navigation enhancement constellation, thereby reducing costs and improving the overall satellite service performance of the constellation. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 A flow chart of the low-orbit ultra-large-scale hybrid constellation star selection method provided by the present invention;

[0057] Figure 2 A schematic diagram of the structure of a low-orbit ultra-large-scale hybrid constellation star selection device provided by the present invention;

[0058] Figure 3 Schematic diagram of the optimization results of the classic single-star selection objective function PDOP and the number of low-orbit satellites used for navigation enhancement;

[0059] Figure 4 Schematic diagram of the optimization results for navigation enhancement of low-orbit inclined constellations Figure 1 ;

[0060] Figure 5 This is a schematic diagram of the evaluation index results for low-orbit inclined constellation navigation enhancement. Figure 2 ;

[0061] Figure 6 Schematic diagram of the optimization results of low-orbit polar orbit constellation navigation enhancement Figure 1 ;

[0062] Figure 7 This is an illustration of the evaluation index results for low-orbit polar orbit constellation navigation enhancement. Figure 2 ;

[0063] Figure 8 Schematic diagram for comparison of single star selection and orbital plane selection results. DETAILED DESCRIPTION

[0064] The following detailed description of the embodiments of the present invention is further described in detail in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the preferred embodiments described, and the scope of the present invention is defined by the claims.

[0065] In the description of the present invention, it should be noted that, unless otherwise specified, “plurality” means two or more than two; the terms “first”, “second”, etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; for ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0066] Embodiment 1

[0067] An embodiment of the present invention provides a method for selecting satellites for a low-orbit ultra-large-scale hybrid constellation, such as Figure 1 As shown, a method for selecting satellites for a low-orbit ultra-large-scale hybrid constellation is characterized by comprising:

[0068] S1. Build a medium-orbit navigation constellation to conduct failure performance analysis, determine the satellite failure mode with the greatest impact, and use the deployed low-orbit satellite constellation for navigation enhancement;

[0069] The failure of medium-orbit navigation constellation satellites will affect the navigation performance of the constellation. A general medium-orbit navigation constellation is constructed. Taking the Walker 24 / 3 / 1 global navigation constellation composed of 24 MEO satellites as an example, the constellation satellite orbit altitude is 20,000 km and the inclination is 55°. The performance after the satellite failure is analyzed. The satellite failure mode with the greatest impact on the construction of a general medium-orbit navigation constellation is used as the input condition. Taking 3 failed satellites as an example, the performance after the satellite failure is analyzed. The reduced constellation availability and increased PDOP value greatly affect the constellation navigation performance.

[0070] The failure of medium-orbit navigation constellation satellites will affect the navigation performance of the constellation. The development of low-orbit satellite integration technology and the integration of communication, navigation and remote sensing technologies have made the constellation no longer limited to a single service. Satellites are selected from the ultra-large-scale constellations that have been deployed or are planned to be deployed to provide navigation enhancement services for medium-orbit navigation constellations.

[0071] Missing functions can be supplemented in time to maintain current functions and avoid causing greater impact.

[0072] S2. Analyze the configuration of the ultra-large-scale low-orbit constellation and determine the navigation enhancement scheme for selecting a single satellite and the navigation enhancement scheme for the orbital plane;

[0073] It is assumed that the ultra-large-scale constellation payload that has been deployed or is planned to be deployed is a communication, navigation and remote sensing integrated constellation, in which the constellation configuration adopts a low-orbit ultra-large-scale hybrid constellation configuration consisting of two orbital layers of the public Starlink constellation (550km 53°, 570km 70°).

[0074] Select satellites from the deployed or planned ultra-large-scale constellations to provide navigation enhancement services for the medium-orbit navigation constellations after satellite failure. Due to the large number of ultra-large-scale low-orbit constellations, there are two options for constellation selection: one is the classic single-star selection, and the other is the satellite orbital plane selection.

[0075] It should be noted that the parameter set for selecting the orbital plane of the LEO ultra-large-scale hybrid constellation is the right ascension of the ascending node of the orbital plane of the hybrid constellation satellite. The hybrid constellation is selected in stages. First, satellites of the inclined constellation are selected to supplement the mid-latitude region, and then satellites of the polar orbit constellation are selected to supplement the polar region. The selection of satellites for the LEO ultra-large-scale hybrid constellation first makes up for the performance deficiencies in the mid-latitude region caused by the failure of the medium-orbit navigation constellation, and then makes up for the performance degradation in the high latitude and polar regions. The use of step-by-step optimization can increase the optimization rate.

[0076] S3, constructing an objective function and a fitness function, and optimizing the single-star selection navigation enhancement scheme and the orbital plane selection navigation enhancement scheme respectively by using the NSGA-II algorithm, the objective function and the fitness function, to obtain optimization results of the two navigation enhancement schemes;

[0077] The objective function is the minimum PDOP value and the total number of satellites selected by the low-orbit constellation. The constellation constraints can be modified according to actual needs, with PDOP≤X as the threshold. The constraints are as low as the performance when the medium-orbit navigation constellation satellite is not invalid, and as high as the GPS constellation navigation performance. The NSGA-II algorithm population and evolution times are debugged, and HV is introduced as the optimization evaluation index to obtain the optimal solution set.

[0078] The single-star selection navigation enhancement scheme includes:

[0079] The single-star selection uses the satellite transit time as the criterion. The single-star selection has a wide range of satellites but will lead to an increase in the amount of calculation.

[0080] Single-star selection requires calculating the number of visible satellites within the time period. Since there are many visible satellites in the low-orbit ultra-large-scale hybrid constellation, in order to improve calculation efficiency, satellites with longer transit times are selected. The performance of different satellite combinations is calculated using an optimization algorithm, and the constellation combination with the smallest PDOP value is selected as navigation enhancement.

[0081] S31. Perform simulation and satellite transit time screening based on the simulation parameters of the Starlink low-orbit large-scale constellation to obtain the screened satellites;

[0082] Due to the large number of low-orbit super-large-scale constellation satellites, in order to improve computing efficiency, satellites with longer transit times are screened out and single satellites are selected.

[0083] S32, using the NSGA-II algorithm to select the screened satellites and determine the selected satellite data;

[0084] S33, based on the star selection data, optimizing using the objective function and constraint conditions;

[0085] S34, introducing an optimization evaluation index, and selecting a unique optimal solution through the fitness function.

[0086] The population and evolution times of NSGA-II algorithm are debugged, and HV is introduced as the optimization evaluation index.

[0087] The S3 orbital plane selection navigation enhancement solution includes:

[0088] The orbital plane is selected as the right ascension of the ascending node of the constellation orbital plane. A smaller number of orbital planes can reduce the search range.

[0089] S35. Perform simulation based on the simulation parameters of the Starlink low-orbit large-scale constellation to determine the constellation orbital plane;

[0090] S36, selecting the constellation orbital plane using the NSGA-II algorithm to obtain an optimized parameter set;

[0091] S37, performing optimization using the objective function and the constraint conditions according to the optimization parameter set;

[0092] S38, introducing the optimization evaluation index, and selecting a unique optimal solution through the fitness function.

[0093] The objective function is as follows:

[0094]

[0095] In the formula, Total is the maximum value of the number of visible satellites;

[0096] The constraint condition is as follows:

[0097]

[0098] In the formula It is the minimum PDOP of the hybrid constellation formed by the low orbit after the failure of the middle orbit between the north and south latitudes m°~n°, and Q is the threshold, which is a constant.

[0099] The optimization result Pareto is a solution set, and the only optimal solution needs to be selected again from the Pareto solution set. A fitness function needs to be designed

[0100] The fitness function is as follows:

[0101]

[0102] Where f1(X) is the PDOP value of the satellite selection scheme X, f2(X) is the total number of satellites selected for the navigation augmentation constellation of the satellite selection scheme X, and V max is the maximum PDOP of the star selection scheme in the Pareto solution set, E max Select the maximum number of satellites for the navigation augmentation constellation, V min is the minimum PDOP value of the star selection scheme in the Pareto solution set, E min The minimum total number of satellites is selected for the navigation augmentation constellation, and PDOP is the position precision factor.

[0103] S4. Compare the optimization results of the two navigation enhancement schemes with the performance of the reference navigation constellation to determine the optimal scheme.

[0104] The optimal solution is compared with the performance of the four traditional navigation constellations, and its performance is better than or equal to the most basic requirements. The two solutions are compared in terms of the total number of navigation constellation satellites, computing overhead, and constellation performance, and reasonable suggestions are given.

[0105] This embodiment is a method for selecting satellites for a low-orbit ultra-large-scale hybrid constellation, including constructing a medium-orbit navigation constellation for failure performance analysis, determining the failure mode of the satellite with the greatest impact and using the deployed low-orbit satellite constellation for navigation enhancement, analyzing the configuration of the low-orbit ultra-large-scale constellation, determining two navigation enhancement schemes of single-star selection and orbital plane selection, constructing an objective function and a fitness function, optimizing the navigation enhancement scheme using the NSGA-II algorithm, the objective function and the fitness function, respectively obtaining the optimization results of the two navigation enhancement schemes, comparing the optimization results of the two navigation enhancement schemes with the performance of the four traditional navigation constellations, and determining the optimal solution. It is intended to quickly make up for the performance degradation of the medium-orbit constellation satellite after failure, and at the same time, there is no need to establish a corresponding navigation enhancement constellation, thereby reducing costs and improving the overall satellite service performance of the constellation.

[0106] Embodiment 2

[0107] An embodiment of the present invention provides a low-orbit ultra-large-scale hybrid constellation star selection device 200, such as Figure 2 As shown, including:

[0108] Failure analysis module 201, used to construct a medium-orbit navigation constellation to perform failure performance analysis, determine the most influential satellite failure mode, and use the deployed low-orbit satellite constellation for navigation enhancement;

[0109] A scheme determination module 202 is used to analyze the configuration of the low-orbit ultra-large-scale constellation and determine a navigation enhancement scheme for selecting a single satellite and a navigation enhancement scheme for selecting an orbital plane;

[0110] The optimization module 203 is used to construct an objective function and a fitness function, and optimize the single-satellite selection navigation enhancement scheme and the orbital plane selection navigation enhancement scheme respectively by using the NSGA-II algorithm, the objective function and the fitness function to obtain optimization results of the two navigation enhancement schemes;

[0111] The optimal determination module 204 is used to compare the optimization results of the two navigation enhancement solutions with the performance of the reference navigation constellation to determine the optimal solution.

[0112] Furthermore, the single-star selection navigation enhancement scheme includes:

[0113] A screening submodule 2031 is used to perform simulation and satellite transit time screening based on simulation parameters of the Starlink low-orbit large-scale constellation to obtain screened satellites;

[0114] The satellite selection submodule 2032 is used to select the selected satellites using the NSGA-II algorithm and determine the satellite selection data;

[0115] A first optimization submodule 2033 is used to perform optimization based on the star selection data using the objective function and constraint conditions;

[0116] The first optimal selection module 2034 is used to introduce an optimization evaluation index and select a unique optimal solution through the fitness function.

[0117] Furthermore, the orbital plane selection navigation enhancement scheme includes:

[0118] The orbital plane determination module 2035 is used to perform simulation based on the simulation parameters of the Starlink low-orbit large-scale constellation to determine the constellation orbital plane;

[0119] The orbital plane selection module 2036 is used to select the orbital plane of the constellation using the NSGA-II algorithm to obtain an optimized parameter set;

[0120] A second optimization submodule 2037, configured to perform optimization based on the optimization parameter set using the objective function and the constraint conditions;

[0121] The second optimal selection module 2038 is used to introduce the optimization evaluation index and select the only optimal solution through the fitness function.

[0122] Furthermore, the objective function is as follows:

[0123]

[0124] In the formula, Total is the maximum value of the number of visible satellites;

[0125] The constraint condition is as follows:

[0126]

[0127] In the formula It is the minimum PDOP of the hybrid constellation formed by the low orbit after the failure of the middle orbit between the north and south latitudes m°~n°, and Q is the threshold, which is a constant.

[0128] Furthermore, the fitness function is as follows:

[0129]

[0130] Where f1(X) is the PDOP value of the satellite selection scheme X, f2(X) is the total number of satellites selected for the navigation augmentation constellation of the satellite selection scheme X, and V max is the maximum PDOP of the star selection scheme in the Pareto solution set, E max Select the maximum number of satellites for the navigation augmentation constellation, V min is the minimum PDOP value of the star selection scheme in the Pareto solution set, E minSelect the minimum total number of satellites for the navigation augmentation constellation.

[0131] Embodiment 3

[0132] The following is a simulation experiment of the low-orbit ultra-large-scale hybrid constellation selection method based on the NSGA-II algorithm. The experimental process is as follows:

[0133] Step 1: Perform failure simulation analysis on the Walker 24 / 3 / 1 global navigation constellation composed of 24 MEO satellites. The failure of one satellite in each orbital plane has the greatest impact on the overall performance of the navigation constellation. The failure of one satellite in each orbital plane is simulated 512 times, and the minimum CV value of the constellation in the satellite failure mode (83.9751%) is used as the input condition, that is, 14-22-35 (the 4th satellite in the 1st orbital plane, the 2nd satellite in the 2nd orbital plane, and the 3rd satellite in the 3rd orbital plane). The scenario parameters are set as follows: simulation time is 24 hours, step size is 60 seconds, minimum observation elevation angle is 5°, grid is 5°×5°, and 2σ (95%) principle is adopted.

[0134] Table 1 The worst 10 satellite failure modes when one satellite fails on each orbital plane and a total of 512 simulations

[0135]

[0136] Step 2: Given the simulation parameters of the Starlink low-orbit large-scale constellation, the low-orbit inclined constellation parameters are: {h = 550km, i = 53°, P = 72, P_num = 22, Total = 1584}; the low-orbit polar constellation parameters are: {h = 570km, i = 70°, P = 36, P_num = 20, Total = 720}.

[0137] For the low-orbit inclined constellation with a total of 1584 satellites and a constellation configuration of {h = 550 km, i = 53°, P = 72, P_num = 22}, the transit time of the target Asia-Pacific region is calculated, and the 300 satellites with the highest transit time are selected. The transit time of some satellites is shown in Table 1.

[0138] Table 2 Transit duration of some of the 300 satellites

[0139]

[0140]

[0141] In Table 1, AreaTarget represents the Asia-Pacific region, with a longitude of -70° to 70° and a latitude of 30° to 180°. Taking Satellite 6909 as an example, 6909 represents the 9th satellite in the 69th orbital plane. The 300 satellites are divided into 25 orbital planes, with the number of satellites in each orbital plane ranging from 3 to 11.

[0142] The NSGA-II algorithm is used to select 300 satellites in 25 orbital planes. The optimization parameter set is the number of satellites in each orbital plane, the population size is 10, and the number of evolutions is 100.

[0143]

[0144] In the formula, They respectively indicate that there are 25 parameter sets in total, indicating the upper and lower bounds of the number of satellites in the orbital plane, and the number of satellites in each orbital plane is different.

[0145] The objective function takes the position precision factor PDOP and the number of selected satellites for navigation enhancement, and adopts the 2σ principle to avoid extreme values ​​of the data as much as possible. The objective function is as follows:

[0146]

[0147] In the formula, PDOP takes the minimum value, and Total takes the maximum value for the number of visible satellites.

[0148] Therefore, the constraints are as follows:

[0149]

[0150] In the formula is the minimum PDOP of the hybrid constellation composed of the low orbit and the middle orbit after the failure of the middle orbit between 60° north and south latitude. Q is the threshold, which is a constant. Here Q=1.3 is taken, so that the navigation performance of the hybrid constellation reaches or exceeds the performance when it has not failed.

[0151] The classic single-star selection optimization results of the low-orbit ultra-large-scale hybrid constellation are as follows: Figure 3 As shown in the figure, although the 300 satellites with the longest transit time are selected, the related satellites do not form a whole, and the classic single-satellite selection scheme does not achieve good results. When the mid-orbit navigation constellation is not invalid, the minimum PDOP is 2.104 (using the 2σ (95%) principle). When all 300 satellites are simulated and the hybrid navigation constellation is formed after the mid-orbit fails, the PDOP changes from the original 2.7091 to 2.0462, which is 0.0578 higher than before.

[0152] Step 3: Also given the simulation parameters of the Starlink low-orbit tilted large-scale constellation {h = 550km, i = 53°, P = 72, P_num = 22, Total = 1584}. 72 orbital planes are selected using the NSGA-II algorithm. The optimized parameter set is the right ascension of the ascending node of the constellation orbital plane, the population size is 10, and the number of evolutions is 100.

[0153]

[0154] In the formula, It indicates that the optimized parameter set includes 72 orbital planes in total, and satellite=22 indicates that there are 22 satellites in each orbital plane.

[0155] The objective function and constraints are the same as above.

[0156] The optimization results are as follows Figure 4 - Figure 5 As shown, Figure 4 To optimize the results, Figure 5 To optimize the evaluation index HV. Since the number of satellites in the orbital plane is fixed, the optimization result is not continuous. Under the objective function and constraint conditions, a relatively good result can be obtained.

[0157] Table 3 PDOP values ​​and number of visible satellites

[0158]

[0159]

[0160] Using the fitness function and data analysis, we can see that the first option is the result of the optimization algorithm, and the second to tenth options are uniformly distributed orbital planes with the same number of satellites. It can be seen that the low-orbit inclined constellation requires 8 orbital planes with a total of 176 satellites to meet the navigation enhancement service in mid-latitude areas after the failure of medium-orbit satellites. The maximum PDOP difference of the optimization result is 0.034, and the average number of visible satellites in the world is maintained at 11.

[0161] Step 4: Based on the above optimization results and simulation data, Scheme 5 is selected as the low-orbit inclined constellation, and the low-orbit polar constellation uses the {h=570km,i=70°,P=36,P_num=20,Total=720} configuration. The NSGA-II algorithm is used to select 36 orbital planes. The optimization parameter set is the right ascension of the ascending node of the constellation orbital plane, the population size is 10, and the number of evolutions is 100.

[0162]

[0163] In the formula, It indicates that the optimized parameter set has 36 orbital planes in total, and satellite=20 indicates that there are 20 satellites in each orbital plane.

[0164] The objective function is the same as above.

[0165] Therefore, the constraints are as follows:

[0166]

[0167] In the formula is the minimum PDOP value of the hybrid constellation composed of the low orbit and the middle orbit after the failure of the middle orbit between 65° and 90° north and south latitude. Q is the threshold value which is a constant. Here Q=1.5 is taken, so that the navigation performance of the hybrid constellation reaches or exceeds the performance when it has not failed.

[0168] The optimization results are as follows Figure 6 - Figure 7 As shown, Figure 6 To optimize the results, Figure 7 To optimize the evaluation index HV. As in step 3, since the number of satellites in the orbital plane is fixed, the optimization result is not continuous. Under the objective function and constraint conditions, a relatively good result can be obtained.

[0169] Table 4 PDOP values ​​and number of visible satellites

[0170]

[0171] Similarly, using the fitness function and data analysis, we can see that the first option is the result of the optimization algorithm, and options 2 to 9 are evenly distributed orbital planes with the same number of satellites. It can be seen that the low-orbit inclined constellation requires 4 orbital planes with a total of 80 satellites to meet the navigation enhancement services in the polar regions after the failure of the medium-orbit satellites. The maximum PDOP difference of the optimization result is 0.025, and the average number of visible satellites in the world is maintained at 14.

[0172] Step 5: Based on the two schemes of single satellite selection and orbital plane selection, low-orbit navigation is enhanced for the failure of the mid-orbit navigation constellation. Through optimization algorithm and relevant data analysis, the following are given: Figure 8 After comparison, the classic single-star selection method is not suitable for low-orbit ultra-large-scale constellations. On the one hand, the calculation overhead increases, and on the other hand, the optimization effect is very different from that of orbital plane selection.

[0173] This embodiment is a low-orbit ultra-large-scale hybrid constellation star selection device, which uses a failure analysis module to construct a medium-orbit navigation constellation for failure performance analysis, determine the satellite failure mode with the greatest impact, and use the deployed low-orbit satellite constellation for navigation enhancement; a solution determination module is used to analyze the configuration of the low-orbit ultra-large-scale constellation and determine two navigation enhancement schemes: single-star selection and orbital plane selection; an optimization module is used to construct an objective function and a fitness function, and optimize the navigation enhancement scheme using the NSGA-II algorithm, the objective function and the fitness function to obtain the optimization results of the two navigation enhancement schemes respectively; and an optimal determination module is used to compare the optimization results of the two navigation enhancement schemes with the performance of the four traditional navigation constellations to determine the optimal solution. It is intended to quickly make up for the performance degradation of the medium-orbit constellation satellite after failure, and at the same time, there is no need to establish a corresponding navigation enhancement constellation, thereby reducing costs and improving the overall satellite service performance of the constellation.

[0174] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for selecting satellites for a low-orbit ultra-large-scale hybrid constellation, characterized in that: include: S1. Build a medium-orbit navigation constellation to conduct failure performance analysis, determine the satellite failure mode with the greatest impact, and use the deployed low-orbit satellite constellation for navigation enhancement; S2. Analyze the configuration of the ultra-large-scale low-orbit constellation and determine the navigation enhancement scheme for selecting a single satellite and the navigation enhancement scheme for the orbital plane; S3, constructing an objective function and a fitness function, and optimizing the single-star selection navigation enhancement scheme and the orbital plane selection navigation enhancement scheme respectively by using the NSGA-II algorithm, the objective function and the fitness function, to obtain optimization results of the two navigation enhancement schemes; S4. Compare the optimization results of the two navigation enhancement schemes with the performance of the reference navigation constellation to determine the optimal scheme; The single-star selection navigation enhancement scheme includes: S31. Perform simulation and satellite transit time screening based on the simulation parameters of the Starlink low-orbit large-scale constellation to obtain the screened satellites; S32, selecting the screened satellites using the NSGA-II algorithm to determine the selected satellite data; S33, based on the star selection data, optimizing using the objective function and constraint conditions; S34, introducing an optimization evaluation index, and selecting a unique optimal solution through the fitness function; The orbital plane selection navigation enhancement scheme includes: S35. Perform simulation based on the simulation parameters of the Starlink low-orbit large-scale constellation to determine the constellation orbital plane; S36. Select the constellation orbital plane using the NSGA-II algorithm to obtain an optimized parameter set; S37, performing optimization using the objective function and the constraint conditions according to the optimization parameter set; S38, introducing the optimization evaluation index, and selecting a unique optimal solution through the fitness function.

2. The method for selecting satellites for a low-orbit ultra-large-scale hybrid constellation according to claim 1, characterized in that: The objective function is as follows: ； Where PDOP is the position precision factor, Take the maximum value for the number of visible satellites; The constraint condition is as follows: ； In the formula It is the minimum PDOP of the hybrid constellation formed by the low orbit after the failure of the middle orbit between the north and south latitudes m°~n°, and Q is the threshold, which is a constant.

3. The method for selecting satellites for a low-orbit ultra-large-scale hybrid constellation according to claim 1, characterized in that: The fitness function is as follows: ； In the formula, For star selection PDOP value, For star selection The total number of satellites selected for the navigation augmentation constellation, is the maximum PDOP of the star selection scheme in the Pareto solution set, Select the maximum number of satellites for the navigation augmentation constellation. is the minimum PDOP value of the star selection scheme in the Pareto solution set, The minimum total number of satellites is selected for the navigation augmentation constellation, and PDOP is the position precision factor.

4. A low-orbit ultra-large-scale hybrid constellation star selection device, characterized in that: include: Failure analysis module, used to build a medium-orbit navigation constellation for failure performance analysis, determine the most influential satellite failure mode, and use the deployed low-orbit satellite constellation for navigation enhancement; The scheme determination module is used to analyze the configuration of the ultra-large-scale low-orbit constellation and determine the navigation enhancement scheme for selecting a single satellite and the navigation enhancement scheme for selecting the orbital plane; An optimization module is used to construct an objective function and a fitness function, and optimize the single-satellite selection navigation enhancement scheme and the orbital plane selection navigation enhancement scheme respectively by using the NSGA-II algorithm, the objective function and the fitness function to obtain optimization results of the two navigation enhancement schemes; An optimal determination module is used to compare the optimization results of the two navigation enhancement schemes with the performance of the reference navigation constellation to determine the optimal scheme; The single-satellite selection navigation enhancement scheme includes: performing simulation and satellite transit time screening based on the simulation parameters of the Starlink low-orbit large-scale constellation to obtain screened satellites; selecting the screened satellites using the NSGA-II algorithm to determine the selection data; optimizing based on the selection data using the objective function and constraint conditions; introducing an optimization evaluation index to select the only optimal solution through the fitness function; The orbital plane selection navigation enhancement scheme includes: simulating based on the simulation parameters of the Starlink low-orbit large-scale constellation to determine the constellation orbital plane; selecting the constellation orbital plane using the NSGA-II algorithm to obtain an optimized parameter set; optimizing according to the optimized parameter set using the objective function and the constraint conditions; introducing the optimization evaluation index and selecting a unique optimal solution through the fitness function.

5. The low-orbit ultra-large-scale hybrid constellation star selection device according to claim 4, characterized in that: The objective function is as follows: ； Where PDOP is the position precision factor, Take the maximum value for the number of visible satellites; The constraint condition is as follows: ； In the formula It is the minimum PDOP of the hybrid constellation formed by the low orbit after the failure of the middle orbit between the north and south latitudes m°~n°, and Q is the threshold, which is a constant.

6. The low-orbit ultra-large-scale hybrid constellation star selection device according to claim 4, characterized in that: The fitness function is as follows: ； In the formula, For star selection PDOP value, For star selection The total number of satellites selected for the navigation augmentation constellation, is the maximum PDOP of the star selection scheme in the Pareto solution set, Select the maximum number of satellites for the navigation augmentation constellation. is the minimum PDOP value of the star selection scheme in the Pareto solution set, The minimum total number of satellites is selected for the navigation augmentation constellation, and PDOP is the position precision factor.

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