An on-orbit field-free pointing calibration method for satellite-borne multi-beam laser rangefinder

Abstract

The present invention discloses an on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder, comprising: selecting a calibration area; obtaining a theoretical pointing angle of the multi-beam laser rangefinder; obtaining satellite attitude information, satellite orbit information, the height of the satellite to a sub-satellite point, and the measured distance from the satellite to the calibration area in the on-orbit stage and normal flight attitude; constructing a laser pointing error solution equation in the on-orbit stage and normal flight attitude; controlling the satellite to perform attitude maneuvers, and constructing a laser pointing error solution equation after attitude maneuvers; calibrating the pointing deviation of the multi-beam laser rangefinder according to the constructed laser pointing error solution equation in the on-orbit stage and normal flight attitude and the constructed laser pointing error solution equation after attitude maneuvers. The present invention discloses a calibration method that does not rely on a calibration field, solves the problem of difficult target laying in the early stage of satellite orbit entry, and can be applied to the geometric positioning of satellite-borne laser rangefinders.

Description

Technical Field

[0001] The invention belongs to the technical field of on-orbit calibration of satellite-borne laser rangefinders, and in particular relates to an on-orbit field-free pointing calibration method for satellite-borne multi-beam laser rangefinders. Background Art

[0002] The vibration of the satellite during launch, the satellite orbit, attitude, time scale, and the ranging and pointing errors of the laser rangefinder ground calibration will reduce the accuracy of the laser measurement results used as elevation control. Therefore, it is necessary to calibrate the laser rangefinder parameters that affect the accuracy on-orbit.

[0003] At present, the calibration methods used for satellite-borne laser rangefinders at home and abroad mainly include ground detector-based method, airborne infrared imaging method, terrain-based calibration method, satellite attitude maneuvering method, etc. Each method has its own advantages and disadvantages. Since domestic large-scale surveying and mapping cameras generally use high-stability large platforms, they are not suitable for satellite attitude maneuvering calibration methods; airborne infrared imaging methods have a low success rate and are difficult to implement. The ground detector-based method has high laying costs and a long calibration cycle.

[0004] Aiming at the difficulty of target laying in the early stage of satellite orbit entry, a field-free pointing calibration method for satellite-borne multi-beam laser rangefinder is proposed. Summary of the invention

[0005] The technology of the present invention solves the problem: overcomes the shortcomings of the prior art and provides an on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder, aiming to solve the problem of difficult target laying in the early stage of satellite orbit entry. It is a calibration method that does not rely on a calibration field and can be applied to the geometric positioning of a satellite-borne laser rangefinder.

[0006] In order to solve the above technical problems, the present invention discloses an on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder, comprising:

[0007] Step 1, select the calibration area;

[0008] Step 2, obtaining the theoretical pointing angle of the multi-beam laser rangefinder;

[0009] Step 3, obtaining satellite attitude information and satellite orbit information in the on-orbit phase and normal flight attitude;

[0010] Step 4, obtaining the height of the satellite to the sub-satellite point in the on-orbit stage and normal flight attitude according to the satellite attitude information and satellite orbit information in the on-orbit stage and normal flight attitude obtained in step 3;

[0011] Step 5: In the calibration area selected in step 1, the multi-beam laser rangefinder is turned on to obtain the actual distance from the satellite to the calibration area in the on-orbit stage and normal flight attitude;

[0012] Step 6, based on the information obtained in steps 3 to 5, construct a solution equation for the laser pointing error in the on-orbit phase and normal flight attitude;

[0013] Step 7, controlling the satellite to perform attitude maneuvers, and constructing a solution equation for the laser pointing error after the attitude maneuvers;

[0014] Step 8, calibrate the pointing deviation of the multi-beam laser rangefinder according to the laser pointing error solution equation in the on-orbit phase and normal flight attitude constructed in step 6 and the laser pointing error solution equation after attitude maneuver constructed in step 7.

[0015] In the above-mentioned on-orbit field-free pointing calibration method for the satellite-borne multi-beam laser rangefinder, the selected calibration area is a flat terrain area, including: oceans, lakes, plains and grasslands.

[0016] In the above-mentioned on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder, obtaining the theoretical pointing angle of the multi-beam laser rangefinder includes:

[0017] Construct a Cartesian coordinate system; the origin O of the Cartesian coordinate system is defined as the satellite mass center; the OZ axis is located in the orbital plane and points to the center of the earth; the OX axis is located in the orbital plane, perpendicular to the OZ axis, and points to the direction of the satellite velocity;

[0018] Before the satellite is launched, the theoretical pointing angle of the three-beam laser of the multi-beam laser rangefinder is obtained according to the installation matrix of the multi-beam laser rangefinder: θ 1 ,θ 2 and θ 3 , that is, the theoretical angles between OA, OB, OC and the Z axis are θ 1 ,θ 2 and θ 3 ; Point A, point B and point C represent the centroid positions of the three-beam laser spot of the multi-beam laser rangefinder on the sea surface; E represents the sub-satellite point position, and the theoretical angles of EA, EB, EC with the X-axis are α 1 , α 2 and α 3 The angles between the three laser beams of the multi-beam laser rangefinder are ∠AOC, ∠BOC and ∠AOB, respectively. 1 , β 3 and β 2 .

[0019] In the above-mentioned on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder, according to the information obtained in steps 3 to 5, a solution equation for the laser pointing error in the on-orbit stage and normal flight attitude is constructed, including:

[0020] According to the information obtained in steps 3 to 5, the coordinates of each point in the on-orbit phase and normal flight attitude are determined as follows:

[0021]

[0022] Among them, θ 1 +Δθ 1 ,θ 2 +Δθ 2 and θ 3 +Δθ 3 Respectively represent the actual angles between OA, OB, OC and the Z axis of the Cartesian coordinate system, Δθ 1 , Δθ 2 and Δθ 3 are the θ caused by the rocket launch vibration and the difference between the satellite and the ground environment. 1 ,θ 2 and θ 3 Deviation of 1 +Δα 1 , α 2 +Δα 2 and α 3 +Δα 3 Respectively represent the actual angles between EA, EB, EC and the X-axis of the Cartesian coordinate system, Δα 1 , Δα 2 and Δα 3 They represent the α caused by the rocket launch vibration and the difference between the satellite and the ground environment. 1 , α 2 and α 3 The deviation of h is the height from the satellite to the sub-satellite point in the on-orbit phase and normal flight attitude;

[0023] In the on-orbit phase and normal flight attitude, the angle β between the three laser beams of the multi-beam laser rangefinder 1 , β 3 and β 2 for:

[0024]

[0025] L 1 , L 2 and L 3 They represent the actual ranging values ​​of the three-beam laser of the multi-beam laser rangefinder in the on-orbit stage and in the normal flight attitude respectively:

[0026]

[0027] Since Δθ 1 , Δθ 2 , Δθ 3 , Δα 1 , Δα 2 , Δα 3 If they are all small, we can simplify them to get:

[0028]

[0029]

[0030]

[0031] In the above-mentioned on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder, the satellite is controlled to perform attitude maneuvers, and a solution equation for the laser pointing error after the attitude maneuvers is constructed, including:

[0032] Sub-step 71, controlling the satellite to perform attitude maneuvers according to the roll angle γ, and obtaining satellite attitude information and satellite orbit information after the attitude maneuvers according to the roll angle γ;

[0033] Sub-step 72, obtaining the altitude of the satellite to the sub-satellite point after the attitude maneuver according to the side swing angle γ based on the satellite attitude information and satellite orbit information after the attitude maneuver according to the side swing angle γ;

[0034] Sub-step 73, in the calibration area selected in step 1, the multi-beam laser rangefinder is turned on to obtain the actual distance from the satellite to the calibration area after the attitude maneuver according to the roll angle γ;

[0035] Sub-step 74, based on the information after the attitude maneuver according to the roll angle γ obtained in sub-steps 71 to 73, construct a solution equation for the laser pointing error after the attitude maneuver according to the roll angle γ.

[0036] In the above-mentioned on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder, according to the information after the attitude maneuver according to the roll angle γ obtained in sub-steps 71 to 73, a solution equation for the laser pointing error after the attitude maneuver according to the roll angle γ is constructed, including:

[0037] According to the information obtained in sub-steps 71 to 73 after the attitude maneuver according to the roll angle γ, it is determined that the coordinates of each point after the attitude maneuver according to the roll angle γ are respectively:

[0038]

[0039] Wherein, point A′, point B′ and point C′ represent the centroid positions of the three-beam laser spot of the multi-beam laser rangefinder on the sea surface after the attitude maneuver according to the roll angle γ; h′ represents the height from the satellite to the sub-satellite point after the attitude maneuver according to the roll angle γ; κ 1 , κ 2 and κ 3 They represent respectively: the angles between the projections of OA, OB, OC on the YOZ plane and the Z axis;

[0040]

[0041] After the satellite performs attitude maneuvers according to the side swing angle γ, the angle between the three laser beams of the multi-beam laser rangefinder remains unchanged:

[0042]

[0043] Among them, L 1 ′, L 2 ′ and L 3 ′ respectively represent the actual ranging values ​​of the three-beam laser of the multi-beam laser rangefinder after the satellite performs attitude maneuvers according to the side swing angle γ:

[0044]

[0045] In the above-mentioned on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder, the pointing deviation of the multi-beam laser rangefinder is calibrated according to the laser pointing error solution equation in the on-orbit stage and normal flight attitude constructed in step 6 and the laser pointing error solution equation after attitude maneuver constructed in step 7, including: combining formulas (1) to (8) to calibrate the pointing deviation of the multi-beam laser rangefinder by least squares.

[0046] In the above-mentioned on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder, the satellite is controlled to perform attitude maneuvers, and a solution equation for the laser pointing error after the attitude maneuvers is constructed, including:

[0047] Sub-step 75, controlling the satellite to perform attitude maneuvers according to the pitch angle ξ, and obtaining satellite attitude information and satellite orbit information after the attitude maneuvers according to the pitch angle ξ;

[0048] Sub-step 76, obtaining the altitude of the satellite to the sub-satellite point after the attitude maneuver according to the pitch angle ξ based on the satellite attitude information and satellite orbit information after the attitude maneuver according to the pitch angle ξ;

[0049] Sub-step 77, in the calibration area selected in step 1, the multi-beam laser rangefinder is turned on to obtain the actual distance from the satellite to the calibration area after the attitude maneuver according to the pitch angle ξ;

[0050] Sub-step 78, based on the information after the attitude maneuver according to the pitch angle ξ obtained in sub-steps 75 to 77, construct a solution equation for the laser pointing error after the attitude maneuver according to the pitch angle ξ.

[0051] In the above-mentioned on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder, according to the information after the attitude maneuvering according to the pitch angle ξ obtained in sub-steps 75 to 77, a solution equation for the laser pointing error after the attitude maneuvering according to the pitch angle ξ is constructed, including:

[0052] According to the information obtained in sub-steps 75 to 77 after the attitude maneuver according to the pitch angle ξ, it is determined that the coordinates of each point after the attitude maneuver according to the pitch angle ξ are:

[0053]

[0054] Among them, point A′, point B′ and point C′ represent the centroid positions of the three-beam laser spot of the multi-beam laser rangefinder on the sea surface after the attitude maneuver according to the pitch angle ξ; h′ represents the height from the satellite to the sub-satellite point after the attitude maneuver according to the pitch angle ξ; κ 1 , κ 2 and κ 3 They represent respectively: the angles between the projections of OA, OB, OC on the YOZ plane and the Z axis;

[0055]

[0056] After the satellite performs attitude maneuvers according to the pitch angle ξ, the angles between the three laser beams of the multi-beam laser rangefinder remain unchanged:

[0057]

[0058] Among them, L′ 1 , L′ 2 and L′ 3 They represent the actual ranging values ​​of the three-beam laser of the multi-beam laser rangefinder after the satellite performs attitude maneuvers according to the pitch angle ξ:

[0059]

[0060] In the on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder, the pointing deviation of the multi-beam laser rangefinder is calibrated according to the laser pointing error solution equation in the on-orbit stage and normal flight attitude constructed in step 6 and the laser pointing error solution equation after attitude maneuver constructed in step 7, including: combining formulas (1) to (5) and (9) to (11), and calibrating the pointing deviation of the multi-beam laser rangefinder by least squares.

[0061] The present invention has the following advantages:

[0062] The invention discloses an on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder. A flat area is selected, and a satellite is maneuvered in different attitudes. The pointing deviation of the multi-beam laser rangefinder is calibrated by using the obtained satellite attitude orbit information and the laser ranging values ​​under different maneuvering conditions. The method is a calibration method that does not rely on a calibration field, solves the problem of difficult target laying in the early stage of satellite orbit entry, and can be applied to the geometric positioning of a satellite-borne laser rangefinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1It is a flowchart of the steps of an on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder in an embodiment of the present invention;

[0064] Figure 2 It is a schematic diagram of the geometric relationship of the pointing direction of a satellite-borne multi-beam laser rangefinder in a normal attitude of a satellite in an embodiment of the present invention;

[0065] Figure 3 It is a schematic diagram of the geometric relationship of the laser pointing of a certain channel of a satellite-borne multi-beam laser rangefinder when a satellite performs a lateral swing maneuver in an embodiment of the present invention;

[0066] Figure 4 The present invention is a schematic diagram of the geometric relationship of the laser pointing of a channel of a satellite-borne multi-beam laser rangefinder when the satellite performs a pitch maneuver in an embodiment of the present invention. DETAILED DESCRIPTION

[0067] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be further described in detail below with reference to the accompanying drawings.

[0068] Example 1

[0069] In this embodiment, a method for on-orbit field-free pointing calibration of a satellite-borne multi-beam laser rangefinder is disclosed. A flat area is selected, and the satellite performs different attitude maneuvers. The laser pointing error is obtained by processing the obtained satellite attitude orbit information and the laser ranging values ​​under different maneuvering conditions.

[0070] like Figure 1 The on-orbit field-free pointing calibration method of the satellite-borne multi-beam laser rangefinder includes:

[0071] Step 1: Select a calibration area. The selected calibration area is a flat terrain area, including but not limited to: oceans, lakes, plains and grasslands.

[0072] Step 2, obtaining the theoretical pointing angle of the multi-beam laser rangefinder, wherein the theoretical pointing angle of the multi-beam laser rangefinder can be determined by the installation matrix of the multi-beam laser rangefinder.

[0073] Step 3, obtain satellite attitude information and satellite orbit information in the on-orbit phase and normal flight attitude. The satellite attitude information can be measured by star sensors and star cameras, and the satellite orbit information can be measured by navigation receivers.

[0074] Step 4, according to the satellite attitude information and satellite orbit information in the on-orbit phase and normal flight attitude obtained in step 3, obtain the height of the satellite to the sub-satellite point in the on-orbit phase and normal flight attitude.

[0075] Step 5: In the calibration area selected in step 1, the multi-beam laser rangefinder is turned on to obtain the actual distance from the satellite to the calibration area in the on-orbit stage and normal flight attitude. The actual distance means that the multi-beam laser rangefinder sends laser to the calibration area and receives the return laser from the calibration area, thereby determining the actual distance from the satellite to the calibration area.

[0076] Step 6, the satellite is maneuvered at a certain angle to obtain satellite attitude information and satellite orbit information after the attitude maneuver. The certain angle attitude maneuver includes but is not limited to: maneuvering at different roll angles, pitch angles and / or yaw angles. After the satellite performs the certain angle attitude maneuver, the angle between the three laser beams of the multi-beam laser rangefinder remains unchanged.

[0077] Step 7: Obtain the altitude of the satellite to the sub-satellite point after the attitude maneuver based on the satellite attitude information and satellite orbit information after the attitude maneuver obtained in step 6.

[0078] Step 8: In the calibration area selected in step 1, the multi-beam laser rangefinder is turned on to obtain the actual distance from the satellite to the calibration area after the attitude maneuver.

[0079] Step 9: Based on the information obtained in steps 4, 5, 6, and 8, the pointing deviation of the multi-beam laser rangefinder is calibrated using the least squares method.

[0080] Example 2

[0081] In this embodiment, the on-orbit field-free pointing calibration method of the satellite-borne multi-beam laser rangefinder includes:

[0082] Step 1: Select the calibration area.

[0083] In this embodiment, the area selected for calibration is the Caspian Sea. By querying meteorological information, it is found that when calibrating on the surface of the Caspian Sea, the weather is clear without cloud cover, the sea surface has small wind and waves, and the wave height is less than 1m.

[0084] Step 2: Obtain the theoretical pointing angle of the multi-beam laser rangefinder.

[0085] In this embodiment, step 2 is specifically implemented as follows: construct a Cartesian coordinate system, wherein the origin O of the Cartesian coordinate system is defined as the satellite mass center; the OZ axis is located in the orbital plane and points to the center of the earth; the OX axis is located in the orbital plane, perpendicular to the OZ axis, and points to the direction of the satellite velocity.

[0086] like Figure 2 Before the satellite is launched, according to the installation matrix of the multi-beam laser rangefinder, the theoretical pointing angle of the three-beam laser of the multi-beam laser rangefinder is obtained: θ 1 ,θ 2 and θ3 , that is, the theoretical angles between OA, OB, OC and the Z axis are θ 1 ,θ 2 and θ 3 Among them, point A, point B and point C represent the centroid positions of the three-beam laser spot of the multi-beam laser rangefinder on the sea surface; E represents the sub-satellite point position, and the theoretical angles between EA, EB, EC and the X-axis are α 1 , α 2 and α 3 The angles between the three laser beams of the multi-beam laser rangefinder are ∠AOC, ∠BOC and ∠AOB, respectively. 1 , β 3 and β 2 .

[0087] According to the satellite pre-launch measurement results:

[0088] [θ 1 θ 2 θ 3 ]=[2.03268° 2.16974° 2.01428°]

[0089] [α 1 α 2 α 3 ]=[90.24780° 92.16763° 90.04802°]

[0090] [β 1 β 2 β 3 ]=[4.04695° 4.18324° 4.20149°]

[0091] It should be noted that due to the rocket launch vibration and the difference in the satellite-ground environment during the on-orbit phase, the actual pointing angle of the multi-beam laser rangefinder deviates from the theoretical pointing angle. The actual pointing angle of the multi-beam laser rangefinder can be expressed as: θ 1 +Δθ 1 ,θ 2 +Δθ 2 and θ 3 +Δθ 3 , that is, θ 1 +Δθ 1 ,θ 2 +Δθ 2 and θ 3 +Δθ 3 Respectively represent the actual angles between OA, OB, OC and the Z axis of the Cartesian coordinate system; Δθ 1 , Δθ 2 and Δθ 3are the θ caused by the rocket launch vibration and the difference between the satellite and the ground environment. 1 ,θ 2 and θ 3 Furthermore, the actual angles between EA, EB, EC and the X-axis of the Cartesian coordinate system are α 1 +Δα 1 , α 2 +Δα 2 and α 3 +Δα 3 , Δα 1 , Δα 2 and Δα 3 They represent the α caused by the rocket launch vibration and the difference between the satellite and the ground environment. 1 , α 2 and α 3 In addition, due to the stability of the subsystem itself, the angle β between the beam lasers 1 , β 3 and β 2 Always remain the same.

[0092] Step 3: Obtain satellite attitude information and satellite orbit information during the on-orbit phase and normal flight attitude.

[0093] In this embodiment, the satellite attitude information and satellite orbit information acquired during the on-orbit phase and in normal flight attitude can be written into satellite auxiliary data and transmitted to the ground together with the laser data.

[0094] Step 4, according to the satellite attitude information and satellite orbit information in the on-orbit phase and normal flight attitude obtained in step 3, obtain the height of the satellite to the sub-satellite point in the on-orbit phase and normal flight attitude.

[0095] In this embodiment, the sequence of the height h of the satellite to the sub-satellite point in the on-orbit phase and normal flight attitude is shown in Table 1 below:

[0096] Serial number Height h(m) 1 491992.3 …… …… n 491783.7 n+1 491762.7

[0097] Table 1

[0098] Step 5: In the calibration area selected in step 1, the multi-beam laser rangefinder is turned on to obtain the actual distance from the satellite to the calibration area in the on-orbit phase and normal flight attitude.

[0099] Step 6: Based on the information obtained in steps 3 to 5, construct a solution equation for the laser pointing error in the on-orbit phase and normal flight attitude.

[0100] In this embodiment, the construction process of the laser pointing error solution equation in the on-orbit stage and normal flight attitude is as follows:

[0101] According to the information obtained in steps 3 to 5, the coordinates of each point in the on-orbit phase and normal flight attitude are determined as follows:

[0102]

[0103] Due to the stability of the subsystem itself, the angle β between the beam lasers 1 , β 3 and β 2 Remain unchanged, that is, in the on-orbit stage and normal flight attitude, the angle between the three laser beams of the multi-beam laser rangefinder is:

[0104]

[0105] L 1 , L 2 and L 3 They represent the actual ranging values ​​of the three-beam laser of the multi-beam laser rangefinder in the on-orbit stage and in the normal flight attitude (i.e., the values ​​of OA, OB and OC):

[0106]

[0107] In the on-orbit phase and normal flight attitude, L 1 , L 2 and L 3 The sequence is shown in Table 2 below:

[0108] Serial number <![CDATA[L 1 (m)]]> <![CDATA[L 2 (m)]]> <![CDATA[L 3 (m)]]> 1 492369.7251 492363.666 492281.7495 …… …… …… …… n 492149.4 492143.3 492061.7 n+1 492139.0 492132.7 492051.4

[0109] Table 2

[0110] Since Δθ 1 , Δθ 2 , Δθ 3 , Δα 1 , Δα 2 , Δα 3 If they are all small, we can simplify them to get:

[0111]

[0112]

[0113]

[0114] Step 7, control the satellite to perform attitude maneuvers, and construct a solution equation for the laser pointing error after the attitude maneuvers.

[0115] In this embodiment, if Figure 3 , taking the side swing angle γ for attitude maneuver as an example, we have:

[0116] Sub-step 71, controlling the satellite to perform attitude maneuvers according to the roll angle γ, and obtaining satellite attitude information and satellite orbit information after the attitude maneuvers according to the roll angle γ. For example, γ = 3.5°.

[0117] Sub-step 72, based on the satellite attitude information and satellite orbit information after the attitude maneuver according to the roll angle γ, obtain the altitude of the satellite to the sub-satellite point after the attitude maneuver according to the roll angle γ.

[0118] Preferably, the sequence of the height h′ of the satellite to the sub-satellite point after the attitude maneuver according to the side swing angle γ is shown in Table 3 below:

[0119] Serial number Height h′(m) 1 488901.4 …… …… n 488619.9 n+1 498601.1

[0120] Table 3

[0121] In sub-step 73, in the calibration area selected in step 1, the multi-beam laser rangefinder is turned on to obtain the actual distance from the satellite to the calibration area after the attitude maneuver according to the roll angle γ.

[0122] Preferably, the actual range value L′ of the three-beam laser of the multi-beam laser rangefinder after the satellite performs attitude maneuvers according to the side swing angle γ is 1 , L′ 2 and L′ 3 The sequence is shown in Table 4 below:

[0123] Serial number <![CDATA[L′ 1 (m)]]> <![CDATA[L′ 2 (m)]]> <![CDATA[L′ 3 (m)]]> 1 490362.5 488697.7 487504.2 …… …… …… …… n 490064.3 488428.2 487320.8 n+1 490044.3 488412.5 487242.9

[0124] Table 4

[0125] Sub-step 74, based on the information after the attitude maneuver according to the roll angle γ obtained in sub-steps 71 to 73, construct a solution equation for the laser pointing error after the attitude maneuver according to the roll angle γ.

[0126] Preferably, according to the information after the posture maneuvering according to the side swing angle γ obtained in sub-steps 71 to 73, it is determined that the coordinates of each point after the posture maneuvering according to the side swing angle γ are respectively:

[0127]

[0128] Wherein, point A′, point B′ and point C′ represent the centroid positions of the three-beam laser spot of the multi-beam laser rangefinder on the sea surface after the attitude maneuver according to the side swing angle γ; κ 1 , κ 2 and κ 3 They respectively represent the angles between the projections of OA, OB, and OC on the YOZ plane and the Z axis.

[0129]

[0130] After the satellite performs attitude maneuvers according to the side swing angle γ, the angle between the three laser beams of the multi-beam laser rangefinder remains unchanged:

[0131]

[0132]

[0133] Step 8, calibrate the pointing deviation of the multi-beam laser rangefinder according to the laser pointing error solution equation in the on-orbit phase and normal flight attitude constructed in step 6 and the laser pointing error solution equation after attitude maneuver constructed in step 7.

[0134] In this embodiment, the error term finally determined is: Δθ 1 , Δθ 2 , Δθ 3 , Δα 1 , Δα 2 , Δα 3 , that is, formulas (1) to (8) can be combined to calibrate the pointing deviation of the multi-beam laser rangefinder through the least square method.

[0135] Example 3

[0136] In this embodiment, the on-orbit field-free pointing calibration method of the satellite-borne multi-beam laser rangefinder includes:

[0137] Step 1: Select the calibration area.

[0138] In this embodiment, the area selected for calibration is the Caspian Sea. By querying meteorological information, it is found that when calibrating on the surface of the Caspian Sea, the weather is clear without cloud cover, the sea surface has small wind and waves, and the wave height is less than 1m.

[0139] Step 2: Obtain the theoretical pointing angle of the multi-beam laser rangefinder.

[0140] In this embodiment, the specific implementation of step 2 is as follows:

[0141] Construct a Cartesian coordinate system, where the origin O of the Cartesian coordinate system is defined as the satellite mass center; the OZ axis is located in the orbital plane and points to the center of the earth; the OX axis is located in the orbital plane, perpendicular to the OZ axis, and points to the direction of the satellite velocity.

[0142] like Figures 2 to 4 Before the satellite is launched, according to the installation matrix of the multi-beam laser rangefinder, the theoretical pointing angle of the three-beam laser of the multi-beam laser rangefinder is obtained: θ 1 ,θ 2 and θ 3 , that is, the theoretical angles between OA, OB, OC and the Z axis are θ 1 ,θ 2 and θ 3Among them, point A, point B and point C represent the centroid positions of the three-beam laser spot of the multi-beam laser rangefinder on the sea surface; E represents the sub-satellite point position, and the theoretical angles between EA, EB, EC and the X-axis are α 1 , α 2 and α 3 The angles between the three laser beams of the multi-beam laser rangefinder are ∠AOC, ∠BOC and ∠AOB, respectively. 1 , β 3 and β 2 .

[0143] According to the satellite pre-launch measurement results:

[0144] [θ 1 θ 2 θ 3 ]=[2.03268° 2.16974° 2.01428°]

[0145] [α 1 α 2 α 3 ]=[90.24780° 92.16763° 90.04802°]

[0146] [β 1 β 2 β 3 ]=[4.04695° 4.18324° 4.20149°]

[0147] It should be noted that due to the rocket launch vibration and the difference in the satellite-ground environment during the on-orbit phase, the actual pointing angle of the multi-beam laser rangefinder deviates from the theoretical pointing angle. The actual pointing angle of the multi-beam laser rangefinder can be expressed as: θ 1 +Δθ 1 ,θ 2 +Δθ 2 and θ 3 +Δθ 3 , that is, θ 1 +Δθ 1 ,θ 2 +Δθ 2 and θ 3 +Δθ 3 Respectively represent the actual angles between OA, OB, OC and the Z axis of the Cartesian coordinate system; Δθ 1 , Δθ 2 and Δθ 3 are the θ caused by the rocket launch vibration and the difference between the satellite and the ground environment. 1 ,θ 2 and θ 3Furthermore, the actual angles between EA, EB, EC and the X-axis of the Cartesian coordinate system are α 1 +Δα 1 , α 2 +Δα 2 and α 3 +Δα 3 , Δα 1 , Δα 2 and Δα 3 They represent the α caused by the rocket launch vibration and the difference between the satellite and the ground environment. 1 , α 2 and α 3 In addition, due to the stability of the subsystem itself, the angle β between the beam lasers 1 , β 3 and β 2 Always remain the same.

[0148] Step 3: Obtain satellite attitude information and satellite orbit information during the on-orbit phase and normal flight attitude.

[0149] In this embodiment, the satellite attitude information and satellite orbit information acquired during the on-orbit phase and in normal flight attitude can be written into satellite auxiliary data and transmitted to the ground together with the laser data.

[0150] Step 4, according to the satellite attitude information and satellite orbit information in the on-orbit phase and normal flight attitude obtained in step 3, obtain the height of the satellite to the sub-satellite point in the on-orbit phase and normal flight attitude.

[0151] Step 5: In the calibration area selected in step 1, the multi-beam laser rangefinder is turned on to obtain the actual distance from the satellite to the calibration area in the on-orbit phase and normal flight attitude.

[0152] Step 6: Based on the information obtained in steps 3 to 5, construct a solution equation for the laser pointing error in the on-orbit phase and normal flight attitude.

[0153] In this embodiment, the construction process of the laser pointing error solution equation in the on-orbit stage and normal flight attitude is as follows: According to the information obtained in steps 3 to 5, the coordinates of each point in the on-orbit stage and normal flight attitude are determined as follows:

[0154]

[0155] Wherein, h represents the altitude from the satellite to the sub-satellite point in the on-orbit phase and normal flight attitude.

[0156] Due to the stability of the subsystem itself, the angle β between the beam lasers 1 , β 3 and β 2Remain unchanged, that is, in the on-orbit stage and normal flight attitude, the angle between the three laser beams of the multi-beam laser rangefinder is:

[0157]

[0158] L 1 , L 2 and L 3 They represent the actual ranging values ​​of the three-beam laser of the multi-beam laser rangefinder in the on-orbit stage and in the normal flight attitude (i.e., the values ​​of OA, OB and OC):

[0159]

[0160] Since Δθ 1 , Δθ 2 , Δθ 3 , Δα 1 , Δα 2 , Δα 3 If they are all small, we can simplify them to get:

[0161]

[0162]

[0163]

[0164] Step 7, control the satellite to perform attitude maneuvers, and construct a solution equation for the laser pointing error after the attitude maneuvers.

[0165] In this embodiment, if Figure 4 , taking the pitch angle ξ as an example, we have:

[0166] Sub-step 75, controlling the satellite to perform attitude maneuvers according to the pitch angle ξ, and obtaining satellite attitude information and satellite orbit information after the attitude maneuvers according to the pitch angle ξ. For example, ξ=3.5°.

[0167] Sub-step 76, based on the satellite attitude information and satellite orbit information after the attitude maneuver according to the pitch angle ξ, the altitude of the satellite to the sub-satellite point after the attitude maneuver according to the pitch angle ξ is obtained.

[0168] Preferably, the sequence of the height h′ of the satellite to the sub-satellite point after the attitude maneuver according to the side swing angle ξ is shown in Table 5 below:

[0169] Serial number Height h′(m) 1 483873.1 …… …… n 488321.9 n+1 493332.3

[0170] Table 5

[0171] In sub-step 77, in the calibration area selected in step 1, the multi-beam laser rangefinder is turned on to obtain the actual measured distance from the satellite to the calibration area after the attitude maneuver according to the pitch angle ξ.

[0172] Preferably, the actual range value L′ of the three-beam laser of the multi-beam laser rangefinder after the satellite performs attitude maneuvers according to the pitch angle ξ 1 , L′ 2 and L′ 3 The sequence is shown in Table 6 below:

[0173] Serial number <![CDATA[L′ 1 (m)]]> <![CDATA[L′ 2 (m)]]> <![CDATA[L′ 3 (m)]]> 1 490232.3 482245.7 484534.4 …… …… …… …… n 494334.3 489533.1 489330.3 n+1 490332.2 488331.1 487184.1

[0174] Table 6

[0175] Sub-step 78, based on the information after the attitude maneuver according to the pitch angle ξ obtained in sub-steps 75 to 77, construct a solution equation for the laser pointing error after the attitude maneuver according to the pitch angle ξ.

[0176] Preferably, according to the information after the attitude maneuvering according to the pitch angle ξ obtained in sub-steps 75 to 77, it is determined that the coordinates of each point after the attitude maneuvering according to the pitch angle ξ are respectively:

[0177]

[0178] Among them, point A′, point B′ and point C′ represent the centroid positions of the three-beam laser spot of the multi-beam laser rangefinder on the sea surface after the attitude maneuver according to the pitch angle ξ; h′ represents the height from the satellite to the sub-satellite point after the attitude maneuver according to the pitch angle ξ; κ 1 , κ 2 and κ 3 They respectively represent the angles between the projections of OA, OB, and OC on the YOZ plane and the Z axis.

[0179]

[0180] After the satellite performs attitude maneuvers according to the pitch angle ξ, the angles between the three laser beams of the multi-beam laser rangefinder remain unchanged:

[0181]

[0182]

[0183] Step 8, calibrate the pointing deviation of the multi-beam laser rangefinder according to the laser pointing error solution equation in the on-orbit phase and normal flight attitude constructed in step 6 and the laser pointing error solution equation after attitude maneuver constructed in step 7.

[0184] In this embodiment, the error term finally determined is: Δθ 1 , Δθ 2 , Δθ3 , Δα 1 , Δα 2 , Δα 3 That is, we can combine formulas (1) to (5) and (9) to (11) to calibrate the pointing deviation of the multi-beam laser rangefinder by the least square method.

[0185] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0186] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. A method for on-orbit field-free pointing calibration of a satellite-borne multi-beam laser rangefinder, characterized in that: include: Step 1, select the calibration area; Step 2, obtaining the theoretical pointing angle of the multi-beam laser rangefinder; Step 3, obtaining satellite attitude information and satellite orbit information in the on-orbit phase and normal flight attitude; Step 4, obtaining the height of the satellite to the sub-satellite point in the on-orbit stage and normal flight attitude according to the satellite attitude information and satellite orbit information in the on-orbit stage and normal flight attitude obtained in step 3; Step 5: In the calibration area selected in step 1, the multi-beam laser rangefinder is turned on to obtain the actual distance from the satellite to the calibration area in the on-orbit stage and normal flight attitude; Step 6, based on the information obtained in steps 3 to 5, construct a solution equation for the laser pointing error in the on-orbit phase and normal flight attitude; Step 7, controlling the satellite to perform attitude maneuvers, and constructing a solution equation for the laser pointing error after the attitude maneuvers; Step 8, calibrating the pointing deviation of the multi-beam laser rangefinder according to the laser pointing error solution equation in the on-orbit stage and normal flight attitude constructed in step 6 and the laser pointing error solution equation after attitude maneuver constructed in step 7; Get the theoretical pointing angle of the multi-beam laser rangefinder, including: Construct a Cartesian coordinate system; the origin O of the Cartesian coordinate system is defined as the satellite mass center; the OZ axis is located in the orbital plane and points to the center of the earth; the OX axis is located in the orbital plane, perpendicular to the OZ axis, and points to the direction of the satellite velocity; Before the satellite is launched, according to the installation matrix of the multi-beam laser rangefinder, the theoretical pointing angles of the three-beam laser of the multi-beam laser rangefinder are obtained: θ1, θ2 and θ3, that is, the theoretical angles between OA, OB, OC and the Z axis are θ1, θ2 and θ3 respectively; among them, point A, point B and point C represent the centroid positions of the three-beam laser spots of the multi-beam laser rangefinder on the sea surface respectively; E represents the sub-satellite point position, and the theoretical angles between EA, EB, EC and the X axis are α1, α2 and α3 respectively; the angles between the three-beam laser of the multi-beam laser rangefinder are ∠AOC, ∠BOC and ∠AOB respectively. Based on the information obtained in steps 3 to 5, the laser pointing error solution equation is constructed in the on-orbit phase and normal flight attitude, including: According to the information obtained in steps 3 to 5, the coordinates of each point in the on-orbit phase and normal flight attitude are determined as follows: Among them, θ1+Δθ1, θ2+Δθ2 and θ3+Δθ3 represent the actual angles between OA, OB, OC and the Z axis of the Cartesian coordinate system, respectively; Δθ1, Δθ2 and Δθ3 represent the deviations of θ1, θ2 and θ3 caused by the rocket launch vibration and the difference between the satellite and the ground environment, respectively; α1+Δα1, α2+Δα2 and α3+Δα3 represent the actual angles between EA, EB, EC and the X axis of the Cartesian coordinate system, respectively; Δα1, Δα2 and Δα3 represent the deviations of α1, α2 and α3 caused by the rocket launch vibration and the difference between the satellite and the ground environment, respectively; h represents the altitude of the satellite to the sub-satellite point in the on-orbit phase and normal flight attitude; In the on-orbit phase and normal flight attitude, the angles β1, β3 and β2 between the three laser beams of the multi-beam laser rangefinder are: L1, L2 and L3 represent the actual ranging values ​​of the three-beam laser of the multi-beam laser rangefinder in the on-orbit stage and normal flight attitude respectively: Since Δθ1, Δθ2, Δθ3, Δα1, Δα2, and Δα3 are all small quantities, we can simplify them to: Control the satellite to perform attitude maneuvers and construct the laser pointing error solution equation after attitude maneuvers, including: Sub-step 71, controlling the satellite to perform attitude maneuvers according to the roll angle γ, and obtaining satellite attitude information and satellite orbit information after the attitude maneuvers according to the roll angle γ; Sub-step 72, obtaining the altitude of the satellite to the sub-satellite point after the attitude maneuver according to the side swing angle γ based on the satellite attitude information and satellite orbit information after the attitude maneuver according to the side swing angle γ; Sub-step 73, in the calibration area selected in step 1, the multi-beam laser rangefinder is turned on to obtain the actual distance from the satellite to the calibration area after the attitude maneuver according to the roll angle γ; Sub-step 74, constructing a laser pointing error solution equation after the attitude maneuver according to the roll angle γ based on the information after the attitude maneuver according to the roll angle γ obtained in sub-steps 71 to 73; Sub-step 75, controlling the satellite to perform attitude maneuvers according to the pitch angle ξ, and obtaining satellite attitude information and satellite orbit information after the attitude maneuvers according to the pitch angle ξ; Sub-step 76, obtaining the altitude of the satellite to the sub-satellite point after the attitude maneuver according to the pitch angle ξ based on the satellite attitude information and satellite orbit information after the attitude maneuver according to the pitch angle ξ; Sub-step 77, in the calibration area selected in step 1, the multi-beam laser rangefinder is turned on to obtain the actual distance from the satellite to the calibration area after the attitude maneuver according to the pitch angle ξ; Sub-step 78, based on the information after the attitude maneuver according to the pitch angle ξ obtained in sub-steps 75 to 77, construct a solution equation for the laser pointing error after the attitude maneuver according to the pitch angle ξ.

2. The on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder according to claim 1, characterized in that: The selected calibration area is a flat terrain area, including: oceans, lakes, plains and grasslands.

3. The on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder according to claim 1, characterized in that: According to the information after the attitude maneuvering according to the roll angle γ obtained in sub-steps 71 to 73, a laser pointing error solution equation after the attitude maneuvering according to the roll angle γ is constructed, including: According to the information obtained in sub-steps 71 to 73 after the attitude maneuver according to the roll angle γ, it is determined that the coordinates of each point after the attitude maneuver according to the roll angle γ are respectively: Among them, point A′, point B′ and point C′ represent the centroid positions of the three-beam laser spot of the multi-beam laser rangefinder on the sea surface after the attitude maneuver according to the roll angle γ; h′ represents the altitude of the satellite to the sub-satellite point after the attitude maneuver according to the roll angle γ; κ1, κ2 and κ3 represent the angles between the projections of OA, OB, OC on the YOZ plane and the Z axis respectively; After the satellite performs attitude maneuvers according to the side swing angle γ, the angle between the three laser beams of the multi-beam laser rangefinder remains unchanged: Among them, L1′, L2′ and L3′ respectively represent the actual ranging values ​​of the three-beam laser of the multi-beam laser rangefinder after the satellite performs attitude maneuvers according to the side swing angle γ:

4. The on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder according to claim 3 is characterized in that: According to the laser pointing error solution equation in the on-orbit stage and normal flight attitude constructed in step 6 and the laser pointing error solution equation after attitude maneuver constructed in step 7, the pointing deviation of the multi-beam laser rangefinder is calibrated, including: combining formulas (1) to (8), and calibrating the pointing deviation of the multi-beam laser rangefinder by least squares.

5. The on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder according to claim 4, characterized in that: According to the information after the attitude maneuvering according to the pitch angle ξ obtained in sub-steps 75 to 77, a laser pointing error solution equation after the attitude maneuvering according to the pitch angle ξ is constructed, including: According to the information obtained in sub-steps 75 to 77 after the attitude maneuver according to the pitch angle ξ, it is determined that the coordinates of each point after the attitude maneuver according to the pitch angle ξ are: Among them, point A′, point B′ and point C′ represent the centroid positions of the three-beam laser spot of the multi-beam laser rangefinder on the sea surface after the attitude maneuver according to the pitch angle ξ; h′ represents the height of the satellite to the sub-satellite point after the attitude maneuver according to the pitch angle ξ; κ1, κ2 and κ3 represent the angles between the projections of OA, OB, OC on the YOZ plane and the Z axis respectively; After the satellite performs attitude maneuvers according to the pitch angle ξ, the angles between the three laser beams of the multi-beam laser rangefinder remain unchanged: Among them, L1′, L2′ and L3′ respectively represent the actual ranging values ​​of the three-beam laser of the multi-beam laser rangefinder after the satellite performs attitude maneuvers according to the pitch angle ξ:

6. The on-orbit field-free pointing calibration method for a satellite-borne multi-beam laser rangefinder according to claim 5, characterized in that: According to the laser pointing error solution equation in the on-orbit stage and normal flight attitude constructed in step 6 and the laser pointing error solution equation after attitude maneuver constructed in step 7, the pointing deviation of the multi-beam laser rangefinder is calibrated, including: combining formulas (1) to (5) and (9) to (11), and calibrating the pointing deviation of the multi-beam laser rangefinder by least squares.

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