Self-adaptive calculation method and task planning method for satellite roll angle

Abstract

The invention discloses a self-adaptive calculation method for a satellite side swing angle, which comprises the following steps of: firstly, determining an approximate top crossing moment of a ground target point based on a first sampling rate orbit, taking an orbit arc section with a preset duration before and after the approximate top crossing moment as an alternative orbit, then determining a required orbit sampling rate, and interpolating the alternative orbit to obtain a first sampling rate orbit and a second sampling rate orbit; the second sampling rate is equal to the needed orbit sampling rate and is higher than the first sampling rate, then calculating to obtain a top crossing moment based on the second sampling rate orbit, and calculating to obtain a satellite side swing angle based on the top crossing moment. According to the method, high-sampling orbit integration is not needed, the sampling rate orbit adaptive to the task requirement is obtained, and the calculation efficiency is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of aerospace technology, and in particular to an adaptive calculation method for a satellite roll angle and a mission planning method. Background Art

[0002] Earth observation remote sensing satellites use onboard microwave and optical remote sensors to perform imaging observations of ground targets. They have good earth observation effects, wide coverage areas, and long durations. Therefore, they have been widely used in many fields such as environmental monitoring, disaster prediction, surveying and exploration, resource surveys, and scientific experiments. In order to expand the scope of earth observation, side-swing imaging technology is usually used on the satellite, so that the satellite-borne equipment can perform side-swing observations in a direction perpendicular to the sub-satellite point trajectory, increasing the possibility of observing ground targets at non-sub-satellite points.

[0003] The roll angle refers to the angle at which the satellite-borne remote sensor deviates from the satellite-ground line when rotating along the vertical orbit direction. For satellites with roll capability, the coverage of the ground at any point on the orbit needs to be determined by combining the field of view of the satellite-borne remote sensor and the roll angle. Therefore, in satellite mission planning, it is often necessary to first calculate the satellite roll angle and then determine the satellite's observation range in order to better plan the mission.

[0004] At present, the satellite overpass time and the satellite roll angle at the ground target point are mostly calculated based on the relative changes of the discrete satellite orbit position time series and the ground target position. If the sampling rate of the satellite orbit time series is large, it will lead to a large deviation in the calculated value of the satellite overpass time, and then introduce a roll angle deviation, which will affect the success or failure of the remote sensing satellite earth observation mission planning. Some existing technical solutions will eliminate or reduce the roll angle deviation by increasing the orbit integration sampling rate. However, due to the high speed of satellite operation, a very high orbit sampling rate is often required, and the higher the orbit accuracy requirements for mission planning, the higher the corresponding orbit sampling rate. This will greatly increase the time for orbit integration and roll angle calculation, affecting the calculation efficiency of roll angle mission planning. Summary of the invention

[0005] In view of some or all of the problems in the prior art, the first aspect of the present invention provides an adaptive calculation method for a satellite side swing angle, comprising:

[0006] Determine an approximate over-the-top time of a ground target point based on the first sampling rate track;

[0007] Taking the orbit arc segments of preset duration before and after the top-passing moment as candidate orbits;

[0008] Determine the desired track sampling rate;

[0009] Interpolating the candidate track to obtain a track with a second sampling rate, wherein the second sampling rate is a required track sampling rate and the second sampling rate is higher than the first sampling rate;

[0010] Calculating the over-the-top time based on the second sampling rate track; and

[0011] Based on the overhead moment, the satellite roll angle is calculated.

[0012] Further, obtaining the first sampling rate track includes:

[0013] Precise orbit determination of satellites based on GNSS observations in satellite telemetry data; and

[0014] According to the orbit determination results, orbit prediction is performed to obtain the first sampling rate orbit.

[0015] Furthermore, the first sampling rate is a 30-second sampling rate.

[0016] Furthermore, determining the approximate top-over time includes:

[0017] Calculate the satellite altitude angle of the ground target point according to the coordinates of the ground target point and the information of the first sampling rate orbit;

[0018] Determining the visible arc segment of the ground target point according to the satellite altitude angle; and

[0019] In the visible arc segment, the time corresponding to the maximum value of the satellite altitude angle is calculated as the approximate time of passing the top.

[0020] Furthermore, the preset duration is 10 minutes before and after the overhead moment.

[0021] Further, determining the required track sampling rate includes:

[0022] Based on the orbit error and satellite velocity in the earth-fixed system, the required orbit sampling rate is calculated.

[0023] Furthermore, a cubic spline interpolation function is used to interpolate the candidate tracks.

[0024] Furthermore, the calculation of the overhead moment includes:

[0025] Calculating the satellite altitude angle of the ground target point according to the coordinates of the ground target point and the information of the second sampling rate orbit;

[0026] Determining the visible arc segment of the ground target point according to the satellite altitude angle; and

[0027] In the visible arc segment, the time corresponding to the maximum value of the satellite altitude angle is calculated as the over-the-top time.

[0028] Based on the above-mentioned adaptive calculation method of satellite side swing angle, the second aspect of the present invention provides a satellite mission planning method, comprising:

[0029] Determine the satellite's overhead time and side swing angle according to the adaptive calculation method as described above; and

[0030] The satellite's observation mission is planned based on the overhead time and the side swing angle.

[0031] A third aspect of the present invention provides a remote sensing satellite, which uses the adaptive calculation method as described above to calculate the roll angle, and performs mission planning based on the roll angle.

[0032] The invention provides an adaptive calculation method for satellite lateral swing angle and a mission planning method, which does not require high sampling orbit integration, obtains a sampling rate orbit that is compatible with the mission requirements, and greatly improves the calculation efficiency. It has been verified that the orbit error introduced by interpolation is less than 5 cm, which can meet the high-precision mission planning requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] To further illustrate the above and other advantages and features of various embodiments of the present invention, a more specific description of various embodiments of the present invention will be presented with reference to the accompanying drawings. It will be understood that these drawings only depict typical embodiments of the present invention and are therefore not to be considered as limiting the scope thereof. In the accompanying drawings, for clarity, identical or corresponding parts will be represented by identical or similar reference numerals.

[0034] Figure 1 A schematic flow chart showing a method for adaptively calculating a satellite side swing angle according to an embodiment of the present invention;

[0035] Figure 2 A schematic diagram showing an approximate overhead time obtained by an adaptive calculation method of a satellite side swing angle according to an embodiment of the present invention;

[0036] Figure 3 A schematic diagram showing the difference between the interpolated orbit and the three components of the original orbit obtained by an adaptive calculation method of a satellite roll angle according to an embodiment of the present invention; and

[0037] Figure 4 A schematic diagram showing the overhead time obtained by an adaptive calculation method of a satellite side swing angle according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In the following description, the present invention is described with reference to various embodiments. However, those skilled in the art will recognize that various embodiments can be implemented without one or more specific details or with other replacement and / or additional methods, materials or components. In other cases, well-known structures, materials or operations are not shown or described in detail to avoid blurring the inventive point of the present invention. Similarly, for the purpose of explanation, specific quantities, materials and configurations are set forth to provide a comprehensive understanding of embodiments of the present invention. However, the present invention is not limited to these specific details. In addition, it should be understood that the various embodiments shown in the drawings are illustrative representations and are not necessarily drawn in correct proportions.

[0039] In this specification, reference to "one embodiment" or "the embodiment" means that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present invention. The phrase "in one embodiment" appearing in various places in this specification does not necessarily all refer to the same embodiment.

[0040] It should be noted that the embodiments of the present invention describe the method steps in a specific order, but this is only for the purpose of illustrating the specific embodiment, rather than limiting the order of the steps. On the contrary, in different embodiments of the present invention, the order of the steps can be adjusted according to actual needs.

[0041] For satellite roll angle planning tasks, a higher orbit sampling rate is often required. For example, the satellite operating speed at an orbit altitude of 500km is about 7.6km / s. For roll angle task planning with an orbit error of 100m, the corresponding orbit sampling rate should be 0.01s. However, usually within a 24h orbit arc, there are only 1 to 2 satellite over-the-top moments available for a ground target point, and the corresponding available observation arc is less than 30 minutes. If the over-the-top moment is calculated on an orbit with a sampling rate of 0.01s throughout the 24h arc, a large amount of additional calculation time will be consumed. Based on this, the present invention provides a high-precision, high-efficiency, and adaptive roll angle calculation method. First, based on a lower sampling rate orbit, such as a 30s sampling rate orbit, the approximate over-the-top moment of the ground target point is searched, and then the orbit arc with a specified time interval before and after the approximate over-the-top moment is used as an alternative orbit. The corresponding satellite orbit sampling rate is calculated according to the mission planning requirements, and then the high sampling rate orbit is obtained by interpolating the alternative orbit. Finally, only the small arc segment orbit is used to calculate the over-the-top moment and its corresponding roll angle. The calculation method does not need to perform high sampling orbit integration to obtain a sampling rate orbit that is suitable for the mission requirements. Taking a 30s sampling rate orbit as an example, compared with a 0.001s sampling rate, the orbit integration time is shortened by 30,000 times, which greatly improves the calculation efficiency while meeting the accuracy requirements of different satellite mission planning types.

[0042] The technical solution of the present invention is further described below in conjunction with the accompanying drawings of the embodiments.

[0043] Figure 1 FIG. 2 is a flow chart showing a method for adaptively calculating a satellite side swing angle according to an embodiment of the present invention. Figure 1 As shown, a method for adaptively calculating a satellite side swing angle includes:

[0044] First, in step 101, a first sampling rate orbit is obtained. The satellite is precisely orbited based on the GNSS observation data in the satellite telemetry data. Then, based on the orbit determination result, an orbit prediction is performed to obtain a first sampling rate orbit. In one embodiment of the present invention, the first sampling rate is a 30-second sampling rate. In one embodiment of the present invention, first, based on the accuracy of the GNSS telemetry data, a suitable dynamic model is established to calculate the initial orbit parameters, and then the orbit is extrapolated based on the initial orbit parameters and the dynamic model to predict the orbit of the first sampling rate;

[0045] Next, in step 102, the approximate time of passing the top is calculated. For a specific ground target point, after the satellite enters, the satellite altitude angle gradually increases, reaches a maximum value when passing the top of the target point, and then gradually drops below the horizon. Therefore, the approximate time of passing the ground target point can be determined based on the first sampling rate orbit. Specifically, in one embodiment of the present invention, the satellite altitude angle of the target point is first calculated based on the coordinates of the ground target point and the orbital information of the first sampling rate orbit obtained in the previous steps. Then, the visible arc segment of the ground target point is determined based on the satellite altitude angle. Finally, the visible arc segment is determined and the time te corresponding to the maximum value of the satellite altitude angle is calculated as the approximate time of passing the top;

[0046] Next, in step 103, the candidate track is determined. The track arc segments with a preset time length before and after the approximate passing time are used as the candidate track. In one embodiment of the present invention, the preset time length is 10 minutes before and after the passing time, that is, the track arc segments with a time interval of 10 minutes before and after the approximate passing time are used as the candidate track;

[0047] Next, in step 104, the orbit sampling rate is determined. According to the satellite velocity and orbit error in the ground-fixed system, the orbit sampling rate suitable for the mission planning is calculated. Since the orbit sampling rate is multiplied by the satellite velocity, the maximum orbit error introduced at the time of passing the top can be calculated. Therefore, according to the predicted orbit error and satellite velocity, the orbit sampling rate suitable for the mission planning can be calculated;

[0048] Next, in step 105, the track is interpolated. The candidate track is interpolated to obtain a track with a second sampling rate, wherein the second sampling rate is the required track sampling rate and the second sampling rate is higher than the first sampling rate. In one embodiment of the present invention, a cubic spline interpolation function is used to interpolate the candidate track; and

[0049] Finally, in step 106, the roll angle is calculated. The overpass time is calculated based on the second sampling rate track, and the satellite roll angle is calculated based on the overpass time. The calculation method of the overpass time is similar to the calculation method of the approximate overpass time. First, the satellite altitude angle of the ground target point is calculated according to the coordinates of the ground target point and the information of the second sampling rate track, and then the visible arc of the ground target point is determined according to the satellite altitude angle. Finally, within the visible arc, the time corresponding to the maximum value of the satellite altitude angle is calculated as the overpass time.

[0050] Figures 2 to 3 The figure shows the process of calculating the roll angle using the adaptive calculation method described above based on the kinematic orbit data of the European Space Agency's SARM-C satellite. The orbit arc length of the SARM-C satellite is 24 hours, and the sampling rate is 1 second. First, the orbit with a sampling rate of 30 seconds is extracted to calculate the approximate passing time te of the ground target point, as shown in Figure 2 As shown in Figure 1, the orbit arc segment 10 minutes before and after time te is extracted and cubic spline interpolation is performed with a sampling rate of 0.001s. The interpolated orbit is compared with the original orbit with a sampling rate of 1s. The results are shown in Figure 1. Figure 3 As shown in Figure 2.3, cubic spline interpolation has boundary effects, that is, the interpolation results at both ends have large errors. Since the top moment is in the middle of the arc segment, the boundary effect has no effect on the algorithm of the present invention. Figure 3 It can be seen that it does not show any boundary effect. Figure 3 It can be seen that the orbit error introduced by interpolation is less than 5 cm, indicating that the calculation method can meet the requirements of high-precision roll angle mission planning. Finally, the high-resolution interpolation orbit is used to calculate the precise time of passing the top and its corresponding roll angle, as shown in Figure 4 This embodiment uses a 30s sampling rate track, and compared with a 0.001s sampling rate, the track integration and the calculation efficiency of the top moment are improved by tens of thousands of times.

[0051] Based on the above-mentioned adaptive calculation method of satellite side swing angle, the present invention also provides a satellite mission planning method, comprising:

[0052] Determine the satellite's overhead time and side swing angle according to the adaptive calculation method as described above; and

[0053] The satellite's observation mission is planned based on the overhead time and the side swing angle.

[0054] In one embodiment of the present invention, after receiving the imaging or data transmission task injected from the ground, the satellite autonomously generates the planning scheme of each task through three links: satellite imaging auxiliary information forecast, task preprocessing, and task planning. In the satellite imaging auxiliary information forecast link, firstly, based on the information such as the overpass time and the sway angle, the ground area that the remote sensing satellite can observe in the future is calculated by the satellite orbit forecast method, and then, according to whether the input imaging task target position is located in the area that the remote sensing satellite can observe and its priority, and whether the energy and storage state estimation information of the remote sensing satellite can meet the imaging task requirements, the task list that can be planned in the future is screened out from the input tasks. In the task preprocessing link, firstly, based on the information such as the sway angle, according to the remote sensing satellite orbit estimation information, the geographical location of the imaging task target in the task list, and the specified observation time, solar altitude angle, imaging resolution, etc. required for each task, all time windows in which each imaging task target can be observed are calculated. Finally, in the task planning stage, based on the observable time window and priority of each task in the task list, the remote sensing satellite control capability is used as a model, and the payload camera power on and off timing, digital antenna power on and off timing, energy status, storage status, etc. are used as constraints to calculate the start and end time of each task and use it as the task planning plan.

[0055] The present invention also provides a remote sensing satellite, which adopts the above-mentioned adaptive calculation method to calculate the roll angle, and performs mission planning based on the roll angle.

[0056] Although various embodiments of the present invention are described above, it should be understood that they are presented as examples only and not as limitations. It is obvious to those skilled in the relevant art that various combinations, modifications and changes can be made thereto without departing from the spirit and scope of the present invention. Therefore, the breadth and scope of the present invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should only be defined according to the attached claims and their equivalents.

Claims

1. A method for adaptively calculating a satellite roll angle, characterized in that: Includes steps: Determine an approximate over-the-top time of a ground target point based on the first sampling rate track; Taking the track arc segment of preset duration before and after the approximate top-passing moment as the candidate track; Determine the desired track sampling rate; Interpolating the candidate track to obtain a track with a second sampling rate, wherein the second sampling rate is equal to the required track sampling rate and is higher than the first sampling rate; Calculate the over-the-top time based on the second sampling rate track; as well as Based on the overhead moment, the satellite roll angle is calculated.

2. The adaptive computing method according to claim 1, characterized in that: The acquisition of the first sampling rate track comprises the steps of: Precise orbit determination of satellites based on GNSS observations in satellite telemetry data; and According to the orbit determination results, orbit prediction is performed to obtain the first sampling rate orbit.

3. The adaptive computing method according to claim 1, characterized in that: The first sampling rate is a 30 second sampling rate.

4. The adaptive computing method according to claim 1, wherein: Determining the approximate top-over time includes the following steps: Calculate the satellite altitude angle of the ground target point according to the coordinates of the ground target point and the information of the first sampling rate orbit; Determine the visible arc segment of the ground target point according to the satellite altitude angle; as well as In the visible arc segment, the time corresponding to the maximum value of the satellite altitude angle is calculated as the approximate time of passing the top.

5. The adaptive computing method according to claim 1, characterized in that: The preset duration is 10 minutes before and after the approximate overhead moment.

6. The adaptive computing method according to claim 1, characterized in that: Determining the required track sampling rate involves the following steps: Based on the orbit error and satellite velocity in the earth-fixed system, the required orbit sampling rate is calculated.

7. The adaptive computing method according to claim 1, characterized in that: The candidate tracks are interpolated using a cubic spline interpolation function.

8. The adaptive computing method according to claim 1, wherein: Calculating the overhead moment includes the following steps: Calculating the satellite altitude angle of the ground target point according to the coordinates of the ground target point and the information of the second sampling rate orbit; Determine the visible arc segment of the ground target point according to the satellite altitude angle; as well as In the visible arc segment, the time corresponding to the maximum value of the satellite altitude angle is calculated as the over-the-top time.

9. A satellite mission planning method, characterized in that: Includes steps: Determining the satellite's overhead time and side swing angle according to the adaptive calculation method according to any one of claims 1 to 8; and The satellite's observation mission is planned based on the overhead time and the side swing angle.

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