Method for calibrating installation error between inertial navigation and photoelectric load based on landmark

Abstract

The invention provides a method for calibrating an installation error between inertial navigation and a photoelectric load based on a landmark, and belongs to the technical field of target geographic positioning. The method comprises the following steps: acquiring position data of a certain landmark in a space geodetic coordinate system; aiming at a landmark by using a photoelectric load, and recording state parameters at the moment, including an initial azimuth angle and an initial pitch angle; in combination with the state parameters, the position data of the landmark are subjected to conversion of multiple coordinate systems in sequence, corresponding calculation is carried out, and the conversion azimuth angle and the conversion pitch angle of the frame angle of the photoelectric load are obtained; calculating an azimuth error angle between the initial azimuth angle and the conversion azimuth angle, and a pitch error angle between the initial pitch angle and the conversion pitch angle; and correcting the frame angle of the photoelectric load by using the azimuth error angle and the pitching error angle to complete the calibration operation. The target positioning precision can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of target geographic positioning, and in particular to a method for calibrating installation errors between an inertial navigation system and an optoelectronic payload based on a landmark. Background Art

[0002] The combination of optoelectronic payload and inertial navigation can realize the function of geographic positioning of the target. Ideally, the line-of-sight coordinate system of the optoelectronic payload should coincide with the inertial navigation coordinate system. However, during the installation of the inertial navigation, there is inevitably a certain installation error between the optoelectronic payload and the inertial navigation system, which causes the two to not completely coincide. That is, the installation error angle between the two coordinate systems causes coordinate rotation, which brings errors to target positioning. In order to improve the accuracy of target positioning, it is necessary to calibrate the installation error between the inertial navigation system and the optoelectronic payload so that the installation error can be corrected. However, the existing calibration methods and existing problems are as follows:

[0003] The first calibration method relies on the design and processing of the optoelectronic payload and the inertial navigation structure. This calibration method has high requirements for structural design, processing and assembly, which brings high costs. At the same time, after multiple mechanical reference conversions, the installation error of this calibration method cannot be guaranteed.

[0004] The second method is the theodolite calibration method, which is to attach a reflector to the reference surface of the inertial navigation system and use the theodolite to calibrate the installation error between the inertial navigation system and the optoelectronic payload. The theodolite calibration method has many disadvantages: first, this calibration method requires the inertial navigation system to have a reference surface, but in reality, many inertial navigation systems do not have a reference surface; second, the installation position of the inertial navigation system and the optoelectronic payload must be close, and the theodolite and the reflector must be self-aligned during calibration, as well as the optoelectronic payload must be aimed at the theodolite; finally, this calibration method has too many calibration links, so it introduces more error sources and the calibration accuracy is not high.

[0005] The third method is the collimator calibration method, which requires calibration of the collimator's yaw angle, attitude angle and other angles before calibration, and has high requirements. In addition, the angle calibration error of the collimator also becomes an error source for target positioning.

[0006] The fourth method is to carry out a flying experiment in the field. The UAV carries an inertial navigation system and an optoelectronic payload. The inertial navigation system is used to record the UAV's track information in real time, and combined with the line of sight attitude during the optoelectronic tracking process, the attitude matrix of the inertial navigation system and the optoelectronic payload can be estimated. However, this calibration method has very high requirements for time synchronization accuracy, which is not easy to guarantee.

[0007] Therefore, in order to calibrate the installation error between the inertial navigation and the optoelectronic payload and improve the target positioning accuracy, it is necessary to propose a solution to improve one or more problems existing in the above-mentioned related technical solutions.

[0008] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present application, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0009] The embodiment of the present application provides a method for calibrating the installation error between an inertial navigation system and an optoelectronic payload based on a landmark, the method comprising the following steps:

[0010] Acquire location data of a landmark in a spatial geodetic coordinate system, wherein the location data includes the longitude, latitude and altitude of the landmark;

[0011] Aim at the landmark using an optoelectronic payload, and record state parameters at this time, wherein the state parameters at least include an initial azimuth angle and an initial pitch angle of a frame angle of the optoelectronic payload;

[0012] Combined with the state parameters, the position data of the landmark is sequentially converted into multiple coordinate systems, and corresponding calculations are performed to obtain the converted azimuth angle and the converted pitch angle of the frame angle of the photoelectric load;

[0013] Calculating an azimuth error angle between the initial azimuth angle and the converted azimuth angle, and a pitch error angle between the initial pitch angle and the converted pitch angle;

[0014] The frame angle of the optoelectronic payload is corrected using the azimuth error angle and the pitch error angle to complete the calibration operation.

[0015] In an exemplary embodiment of the present application, the step of obtaining the position data of a landmark in a spatial geodetic coordinate system includes: measuring the landmark using a high-precision GPS to obtain the position data.

[0016] In an exemplary embodiment of the present application, the state parameters include the initial azimuth angle, the initial pitch angle, the inertial navigation heading angle, the inertial navigation attitude angle and the inertial navigation position data;

[0017] The inertial navigation attitude angle includes an inertial navigation pitch angle and an inertial navigation roll angle; and the inertial navigation position data includes the longitude, latitude and altitude of the inertial navigation.

[0018] In an exemplary embodiment of the present application, the steps of converting the position data of the landmark into multiple coordinate systems in sequence in combination with the state parameters, and performing corresponding calculations to obtain the converted azimuth angle and the converted pitch angle of the frame angle of the photoelectric load include:

[0019] Converting the position data of the landmark in a geocentric coordinate system to obtain the landmark coordinates in the geocentric coordinate system;

[0020] Converting the landmark coordinates in the geocentric coordinate system into the relative coordinate system to obtain the landmark coordinates in the relative coordinate system;

[0021] Converting the landmark coordinates in the relative coordinate system into the northeast celestial coordinate system to obtain the landmark coordinates in the northeast celestial coordinate system;

[0022] Convert the landmark coordinates in the northeast celestial coordinate system into the inertial navigation coordinate system to obtain the landmark coordinates in the inertial navigation coordinate system;

[0023] The converted azimuth angle and the converted elevation angle are calculated using the landmark coordinates in the inertial navigation coordinate system.

[0024] In an exemplary embodiment of the present application, the longitude of the spatial geodetic coordinate system is the angle between the plane where the spatial point and the rotation axis of the reference ellipsoid are located and the starting meridian plane of the reference ellipsoid, the latitude of the spatial geodetic coordinate system is the angle between the normal line of the spatial point and the reference ellipsoid surface and the equatorial plane, and the altitude of the spatial geodetic coordinate system is the distance from the spatial point to the reference ellipsoid surface along the normal line direction of the reference ellipsoid; the position data of the landmark in the spatial geodetic coordinate system is (L d ,B d ,H d ) T , where T represents the transpose of the matrix;

[0025] The origin of the geocentric coordinate system is the center of the reference ellipsoid. d The X axis of the reference ellipsoid coincides with the rotation axis of the reference ellipsoid, with the upward direction being positive. d The Y axis is the intersection of the Greenwich meridian plane and the Earth's equatorial plane, and is positive outward. d The axis is in the equatorial plane and is aligned with the X d Axis and Z d The axes form a right-handed coordinate system;

[0026] The calculation formula of the landmark coordinates in the geocentric coordinate system is:

[0027]

[0028] Among them, g x X represents the geocentric coordinate system d Axis landmark coordinates, g y Y represents the geocentric coordinate system d Axis landmark coordinates, g z Z represents the geocentric coordinate system d The coordinates of the axis landmark, H d Indicates the height of the landmark, B d Indicates the latitude of the landmark, L dIndicates the longitude of the landmark, a represents the equatorial radius of the earth, b represents the polar radius of the earth, and the coordinates of the landmark in the geocentric coordinate system are (g x ,g y ,g z ) T .

[0029] In an exemplary embodiment of the present application, the relative coordinate system is a three-dimensional rectangular coordinate system independently defined to realize the conversion from the northeast celestial coordinate system to the geocentric coordinate system. The origin of the relative coordinate system is the projection of the center of mass of the inertial navigation on the surface of the earth. r The X axis of the geocentric coordinate system d The axes are parallel and in the same direction, and the Y r The Y axis of the geocentric coordinate system d The axes are parallel and in the same direction, and the Z r The Z axis of the geocentric coordinate system d The axes are parallel and in the same direction;

[0030] The calculation formula of the landmark coordinates in the relative coordinate system is:

[0031]

[0032] Among them, (r x ,r y ,r z ) T Represents the landmark coordinates in the relative coordinate system, r x X represents the relative coordinate system r The coordinates of the axis landmarks, r y Represents the Y of the relative coordinate system r The coordinates of the axis landmarks, r z Represents the Z of the relative coordinate system r The coordinates of the axis landmarks, B represents the latitude of the inertial navigation system, and L represents the longitude of the inertial navigation system.

[0033] In an exemplary embodiment of the present application, the origin of the northeast celestial coordinate system is the center of mass of the inertial navigation system, and the X G The axis points to the east, and the Y axis of the northeast celestial coordinate system G The axis points to due north, and the Z axis of the northeast celestial coordinate system G The axis points to the sky along the vertical line of the earth;

[0034] The calculation formula of the landmark coordinates in the northeast celestial coordinate system is:

[0035]

[0036] Among them, (n x ,n y ,n z ) T Represents the landmark coordinates in the northeast celestial coordinate system, n x X represents the northeast celestial coordinate system G Axis landmark coordinates, n y Y represents the northeast celestial coordinate system G Axis landmark coordinates, n z Z represents the northeast celestial coordinate system G The landmark coordinates of the axis, H represents the height of the inertial navigation, represents the transformation matrix in the northeast sky coordinate system,

[0037] In an exemplary embodiment of the present application, the origin of the inertial navigation coordinate system is the center of mass of the inertial navigation, the X-axis of the inertial navigation coordinate system points to the horizontal axis of the installation plane of the inertial navigation, the Y-axis of the inertial navigation coordinate system points to the longitudinal axis of the installation plane of the inertial navigation, and the Z-axis of the inertial navigation coordinate system is perpendicular to the plane and points to the zenith, and forms a right-handed coordinate system with the X-axis and the Y-axis;

[0038] The calculation formula of the landmark coordinates in the inertial navigation coordinate system is:

[0039]

[0040] Among them, (c x ,c y ,c z ) T represents the landmark coordinates in the inertial navigation coordinate system, c x represents the landmark coordinate of the X axis of the inertial navigation coordinate system, c y represents the Y-axis landmark coordinate of the inertial navigation coordinate system, c z Represents the landmark coordinates of the Z axis of the inertial navigation coordinate system, represents the transformation matrix in the inertial navigation coordinate system, θ represents the inertial navigation heading angle, ε represents the inertial navigation pitch angle, and γ represents the inertial navigation roll angle.

[0041] In an exemplary embodiment of the present application, the calculation formula of the conversion azimuth angle is:

[0042]

[0043] Among them, α2 represents the conversion azimuth;

[0044] The calculation formula for the conversion pitch angle is:

[0045]

[0046] Among them, β2 represents the conversion pitch angle;

[0047] The calculation formula of the azimuth error angle is:

[0048] α′=α1-α2 (7)

[0049] Among them, α′ represents the azimuth error angle, and α1 represents the initial azimuth angle;

[0050] The calculation formula of the pitch error angle is:

[0051] β′=β1-β2 (8)

[0052] Where β′ represents the pitch error angle, and β1 represents the initial pitch angle.

[0053] In an exemplary embodiment of the present application, the step of correcting the frame angle of the optoelectronic payload by using the azimuth error angle and the pitch error angle to complete the calibration operation includes:

[0054] Measuring the corrected front position angle and the corrected front pitch angle of the frame angle by using an angle measuring sensor;

[0055] Calculating a corrected azimuth angle of the frame angle using the azimuth error angle, and calculating a corrected pitch angle of the frame angle using the pitch error angle;

[0056] The calculation formula of the corrected azimuth is:

[0057] α 后 =α 前 -α′ (9)

[0058] Among them, α 后 represents the corrected azimuth of the frame angle, α 前 Indicates the corrected forward angle of the frame angle;

[0059] The calculation formula of the corrected pitch angle is:

[0060] β 后 =β 前 -β′ (10)

[0061] Among them, β 后 represents the corrected pitch angle of the frame angle, β 前 Indicates the corrected pitch angle of the frame angle.

[0062] Beneficial effects:

[0063] The present application provides a method for calibrating the installation error between an inertial navigation system and an optoelectronic payload based on a landmark, which has at least the following beneficial effects:

[0064] (1) This application only needs to operate the photoelectric load to aim at the landmark and complete the recording of the state parameters, and the calibration calculation can be completed online or offline. Therefore, the calibration operation is simpler than the existing technology;

[0065] (2) In addition to the state parameters involved in the calibration calculation, the present application avoids other new error sources during the calibration process. Therefore, the calibration accuracy is more accurate than the prior art;

[0066] (3) In addition to the optoelectronic payload, inertial navigation and high-precision GPS, no additional equipment is required for calibration in this application. Therefore, the calibration equipment has lower hardware requirements than the existing technology;

[0067] (4) This application is applicable to ground calibration or calibration in the suspended state, and has a wider adaptability;

[0068] (5) This application has no requirements on the installation location of the optoelectronic payload and the inertial navigation system, or the distance between them, and is more suitable for target positioning using the inertial navigation data of the UAV;

[0069] (6) This application does not require a reference surface for inertial navigation. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] The drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0071] Figure 1 A schematic diagram showing the steps of a method for calibrating installation errors between an inertial navigation system and an optoelectronic payload based on a landmark in an exemplary embodiment of the present application;

[0072] Figure 2 A schematic flow chart showing a method for calibrating installation errors between an inertial navigation system and an optoelectronic payload based on a landmark in an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0073] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0074] In addition, the accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0075] To this end, this example embodiment provides a calibration method for the installation error between the inertial navigation and the optoelectronic payload based on the landmark, such as Figure 1 As shown, the method may include the following steps:

[0076] Step S101: obtaining the position data of a certain landmark in the spatial geodetic coordinate system, the position data including the longitude, latitude and altitude of the landmark;

[0077] Step S102: aiming at the landmark using the photoelectric payload, and recording the state parameters at this time, the state parameters at least including the initial azimuth angle and initial pitch angle of the frame angle of the photoelectric payload;

[0078] Step S103: combining the state parameters, sequentially transforming the location data of the landmark into multiple coordinate systems, and performing corresponding calculations to obtain the transformed azimuth angle and the transformed pitch angle of the frame angle of the photoelectric load;

[0079] Step S104: calculating an azimuth error angle between an initial azimuth angle and a converted azimuth angle, and a pitch error angle between an initial pitch angle and a converted pitch angle;

[0080] Step S105: Correct the frame angle of the optoelectronic payload using the azimuth error angle and the elevation error angle to complete the calibration operation.

[0081] The embodiment of the present application proposes a calibration method for the installation error between an inertial navigation system and an optoelectronic payload based on a landmark, which has at least the following beneficial effects:

[0082] (1) This application only needs to operate the photoelectric load to aim at the landmark and complete the recording of the state parameters, and the calibration calculation can be completed online or offline. Therefore, the calibration operation is simpler than the existing technology;

[0083] (2) In addition to the state parameters involved in the calibration calculation, the present application also avoids other new error sources during the calibration process. Therefore, the calibration accuracy is more accurate than the prior art;

[0084] (3) In addition to the optoelectronic payload, inertial navigation and high-precision GPS, no additional equipment is required for calibration in this application. Therefore, the calibration equipment has lower hardware requirements than the existing technology;

[0085] (4) This application is applicable to ground calibration or calibration in the suspended state, and has a wider adaptability;

[0086] (5) This application has no requirements on the installation location of the optoelectronic payload and the inertial navigation system, or the distance between them, and is more suitable for target positioning using the inertial navigation data of the UAV;

[0087] (6) This application does not require a reference surface for inertial navigation.

[0088] Next, a method for calibrating the installation error between the landmark-based inertial navigation system and the optoelectronic payload proposed in this example embodiment will be described in more detail.

[0089] In an embodiment of the present application, a method for calibrating the installation error between an inertial navigation system and an optoelectronic payload based on a landmark is proposed to calibrate the installation error between the inertial navigation system and the optoelectronic payload and improve the target positioning accuracy.

[0090] In step S101 of this embodiment, the position data of a certain landmark in the spatial geodetic coordinate system is obtained, and the position data includes the longitude, latitude and altitude of the landmark.

[0091] Furthermore, in this embodiment, a high-precision GPS device is used to measure the geodetic position coordinates of the landmark in a spatial geodetic coordinate system. The high-precision GPS device is preferably a differential GPS device. Here, the higher the positioning accuracy of the differential GPS device, the better. The positioning accuracy of the differential GPS device selected in this embodiment is less than 1 meter.

[0092] Furthermore, the longitude of the spatial geodetic coordinate system is the angle between the plane where the spatial point and the rotation axis of the reference ellipsoid are located and the starting meridian plane of the reference ellipsoid. The latitude of the spatial geodetic coordinate system is the angle between the normal line of the spatial point and the reference ellipsoid surface and the equatorial plane. The altitude of the spatial geodetic coordinate system is the distance from the spatial point to the reference ellipsoid surface along the normal line of the reference ellipsoid. The position data of the landmark in the spatial geodetic coordinate system is (L d ,B d ,H d ) T , where T represents the transpose of the matrix.

[0093] Furthermore, in this embodiment, the geodetic coordinates of a known landmark are measured using a differential GPS device, and the longitude of the landmark is measured: d =124.482628°, latitude of landmark: B d =47.520313°, height of landmark: H d = 166.2 meters. In step S102 of this embodiment, the photoelectric load is used to aim at the landmark, and the state parameters at this time are recorded.

[0094] Furthermore, in this embodiment, the optoelectronic payload is hoisted under the drone, and the handle is operated to manually aim the optoelectronic payload at the landmark through the drone data link. The initial azimuth and initial pitch angles, inertial navigation heading angles, inertial navigation attitude angles, inertial navigation position data and other state parameters of the optoelectronic payload are recorded.

[0095] The inertial navigation attitude angle includes the inertial navigation pitch angle and the inertial navigation roll angle.

[0096] The inertial navigation position data includes the longitude, latitude and altitude of the inertial navigation.

[0097] Furthermore, this embodiment records the following 5 sets of data, see Table 1 below for details:

[0098] Table 1: Five groups of status parameters recorded

[0099]

[0100] In step S103 of this embodiment, the location data of the landmark is sequentially converted into multiple coordinate systems in combination with the state parameters, and corresponding calculations are performed to obtain the converted azimuth angle and the converted pitch angle of the frame angle of the photoelectric load. Step S103 of this embodiment includes the following sub-steps:

[0101] Sub-step S1031: converting the location data of the landmark in the geocentric coordinate system to obtain the coordinates of the landmark in the geocentric coordinate system.

[0102] Furthermore, the origin of the geocentric coordinate system is the center of the reference ellipsoid, and the Z d The axis coincides with the rotation axis of the reference ellipsoid, with the upward direction being positive. d The Y axis is the intersection of the Greenwich meridian plane and the Earth's equatorial plane. The positive axis is outward. d The axis is in the equatorial plane and is aligned with the X d Axis and Z d The axes form a right-handed coordinate system.

[0103] Furthermore, the calculation formula of the landmark coordinates in the geocentric coordinate system is:

[0104]

[0105] Among them, g x X represents the geocentric coordinate system d Axis landmark coordinates, g y Y represents the geocentric coordinate d Axis landmark coordinates, g z Z represents the geocentric coordinate system d The coordinates of the axis landmark, H d Indicates the height of the landmark, B d Indicates the latitude of the landmark, Ld Indicates the longitude of the landmark, a represents the equatorial radius of the earth. In this embodiment, the value of a is 6378137m. b represents the polar radius of the earth. In this embodiment, the value of b is 6356752m. The coordinates of the landmark in the geocentric coordinate system are (g x ,g y ,g z ) T .

[0106] Sub-step S1032: converting the landmark coordinates in the geocentric coordinate system into the relative coordinate system to obtain the landmark coordinates in the relative coordinate system.

[0107] Furthermore, the relative coordinate system is a three-dimensional rectangular coordinate system independently defined to achieve the conversion from the northeast celestial coordinate system to the geocentric coordinate system. The origin of the relative coordinate system is the projection of the mass center of the inertial navigation on the surface of the earth. r Axis and the X of the geocentric coordinate system d The axes are parallel and in the same direction, relative to the Y coordinate system r Axis and the Y of the geocentric coordinate system d The axes are parallel and in the same direction, relative to the Z coordinate system r Axis and the Z of the geocentric coordinate system d The axes are parallel and in the same direction.

[0108] Furthermore, the calculation formula of the landmark coordinates in the relative coordinate system is:

[0109]

[0110] Among them, (r x ,r y ,r z ) T Represents the landmark coordinates in the relative coordinate system, r x X represents the relative coordinate system r The coordinates of the axis landmarks, r y Represents the Y of the relative coordinate system r The coordinates of the axis landmarks, r z Represents the Z of the relative coordinate system r The coordinates of the axis landmarks, B represents the latitude of the inertial navigation system, and L represents the longitude of the inertial navigation system.

[0111] Sub-step S1033: converting the landmark coordinates in the relative coordinate system into the northeast celestial coordinate system to obtain the landmark coordinates in the northeast celestial coordinate system.

[0112] Furthermore, the origin of the Northeast Sky coordinate system is the center of mass of the inertial navigation system. GThe axis points to the east, the Y axis of the northeast celestial coordinate system G The axis points to due north, the Z of the northeast celestial coordinate system G The axis points toward the sky along the line perpendicular to the earth.

[0113] Furthermore, the calculation formula of the landmark coordinates in the northeast celestial coordinate system is:

[0114]

[0115] Among them, (n x ,n y ,n z ) T Represents the landmark coordinates in the northeast celestial coordinate system, n x X represents the northeast celestial coordinate system G Axis landmark coordinates, n y Y represents the northeast celestial coordinate system G Axis landmark coordinates, n z Z represents the northeast celestial coordinate system G The landmark coordinates of the axis, H represents the height of the inertial navigation, represents the transformation matrix in the northeast sky coordinate system,

[0116] Sub-step S1034: converting the landmark coordinates in the northeast celestial coordinate system into the inertial navigation coordinate system to obtain the landmark coordinates in the inertial navigation coordinate system.

[0117] Furthermore, the origin of the inertial navigation coordinate system is the center of mass of the inertial navigation, the X-axis of the inertial navigation coordinate system points to the horizontal axis of the installation plane of the inertial navigation, the Y-axis of the inertial navigation coordinate system points to the vertical axis of the installation plane of the inertial navigation, and the Z-axis of the inertial navigation coordinate system is perpendicular to the plane and points to the zenith, and forms a right-handed coordinate system with the X-axis and the Y-axis.

[0118] Furthermore, the calculation formula of the landmark coordinates in the inertial navigation coordinate system is:

[0119]

[0120] Among them, (c x ,c y ,c z ) T represents the landmark coordinates in the inertial navigation coordinate system, c x represents the landmark coordinate of the X axis of the inertial navigation coordinate system, c y represents the Y-axis landmark coordinate of the inertial navigation coordinate system, c z Represents the landmark coordinates of the Z axis of the inertial navigation coordinate system, represents the transformation matrix in the inertial navigation coordinate system, θ represents the inertial navigation heading angle, ε represents the inertial navigation pitch angle, and γ represents the inertial navigation roll angle.

[0121] The data in Table 1 are sequentially substituted into the calculation formulas of sub-steps S1031 to S1034 for conversion and calculation. The calculation process is not described in detail in this embodiment.

[0122] Sub-step S1035: Calculate the conversion azimuth angle and the conversion pitch angle using the inertial navigation position coordinates.

[0123] Furthermore, the calculation formula for the conversion azimuth is:

[0124]

[0125] Wherein, α2 represents the conversion azimuth angle.

[0126] The calculation formula for converting the pitch angle is:

[0127]

[0128] Wherein, β2 represents the conversion pitch angle.

[0129] In step S104 of this embodiment, an azimuth error between the initial azimuth and the converted azimuth, and a pitch error between the initial elevation and the converted elevation are calculated.

[0130] Furthermore, the calculation formula of the azimuth error angle is:

[0131] α′=α1-α2 (7)

[0132] Wherein, α′ represents the azimuth error angle, and α1 represents the initial azimuth angle.

[0133] The calculation formula for the pitch error angle is:

[0134] β′=β1-β2 (8)

[0135] Where β′ represents the pitch error angle, and β1 represents the initial pitch angle.

[0136] Further, after conversion and calculation from sub-step S1031 to sub-step S1035, the installation error angle is obtained, and the installation error includes the azimuth error angle and the pitch error angle. The calculation results of five groups of installation error angles corresponding to Table 1 are recorded here, as shown in Table 2 below:

[0137] Table 2: Calculation results of five groups of installation error angles

[0138]

[0139] From Table 2, we can see that by averaging the five groups of installation error angles, we can get the final installation error angle result, that is, the azimuth error angle α ′ =1.515°, pitch error angle β′ =-0.397°.

[0140] In step S105 of this embodiment, the frame angle of the optoelectronic payload is corrected using the azimuth error angle and the elevation error angle to complete the calibration operation. Step S105 of this embodiment includes the following sub-steps:

[0141] Sub-step S1051: using an angle measuring sensor to measure the corrected front azimuth angle and the corrected front pitch angle of the frame angle.

[0142] Sub-step S1052: Calculate the corrected azimuth angle of the frame angle of the photoelectric payload using the azimuth error angle, and calculate the corrected pitch angle of the frame angle of the photoelectric payload using the pitch error angle.

[0143] Furthermore, the calculation formula of the corrected azimuth angle is:

[0144] α 后 =α 前 -α′ (9)

[0145] Among them, α 后 represents the corrected azimuth of the frame angle, α 前 Indicates the corrected forward orientation angle of the frame angle.

[0146] The calculation formula of the corrected pitch angle is:

[0147] β 后 =β 前 -β′ (10)

[0148] Among them, β 后 represents the corrected pitch angle of the frame angle, β 前 Indicates the corrected pitch angle of the frame angle.

[0149] What needs to be further explained in the present application is that: in step S105, the origin of the sighting line coordinate system of the optoelectronic load is the center of mass of the optoelectronic load, the X-axis points to the horizontal axis of the optical bench of the optoelectronic load, the Y-axis points to the vertical axis of the optical bench of the optoelectronic load, and the Z-axis is perpendicular to the XY-axis plane and points to the zenith, forming a right-handed coordinate system.

[0150] The present application is applicable to hoisted and horizontally mounted two-axis photoelectric loads. The frame angle of the hoisted photoelectric load includes the azimuth angle and the pitch angle, and the frame angle of the horizontally mounted photoelectric load includes the roll angle and the pitch angle. In this embodiment, a hoisted two-axis photoelectric load is used as an example for explanation. If it is a horizontally mounted photoelectric load, it is only necessary to modify the formulas accordingly according to steps S101 to S105, and then substitute the roll angle and the pitch angle into the modified formulas for calculation, and no further details will be given here.

[0151] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0152] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0153] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed in the present application, and these modifications or substitutions should be included in the protection scope of the present application.

[0154] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary technical means in the art that are not disclosed in the present application.

Claims

1. A method for calibrating the installation error between an inertial navigation system and an optoelectronic payload based on a landmark, characterized in that: The method comprises the following steps: Acquire location data of a landmark in a spatial geodetic coordinate system, wherein the location data includes the longitude, latitude and altitude of the landmark; Aim at the landmark using an optoelectronic payload, and record state parameters at this time, wherein the state parameters at least include an initial azimuth angle and an initial pitch angle of a frame angle of the optoelectronic payload; Combined with the state parameters, the position data of the landmark is sequentially converted into multiple coordinate systems, and corresponding calculations are performed to obtain the converted azimuth angle and the converted pitch angle of the frame angle of the photoelectric load; Calculating an azimuth error angle between the initial azimuth angle and the converted azimuth angle, and a pitch error angle between the initial pitch angle and the converted pitch angle; The frame angle of the optoelectronic payload is corrected using the azimuth error angle and the pitch error angle to complete the calibration operation.

2. The method for calibrating the installation error between the inertial navigation system and the optoelectronic payload based on the landmark according to claim 1, characterized in that: The step of obtaining the position data of a certain landmark in the spatial geodetic coordinate system includes: measuring the landmark using a high-precision GPS to obtain the position data.

3. The method for calibrating the installation error between the inertial navigation system and the optoelectronic payload based on the landmark according to claim 2, characterized in that: The state parameters include the initial azimuth angle, the initial pitch angle, the inertial navigation heading angle, the inertial navigation attitude angle and the inertial navigation position data; The inertial navigation attitude angle includes an inertial navigation pitch angle and an inertial navigation roll angle; and the inertial navigation position data includes the longitude, latitude and altitude of the inertial navigation.

4. The method for calibrating the installation error between the inertial navigation system and the optoelectronic payload based on the landmark according to claim 3 is characterized in that: The step of converting the position data of the landmark into multiple coordinate systems in sequence in combination with the state parameters and performing corresponding calculations to obtain the converted azimuth angle and the converted pitch angle of the frame angle of the photoelectric load comprises: Converting the position data of the landmark in a geocentric coordinate system to obtain the landmark coordinates in the geocentric coordinate system; Converting the landmark coordinates in the geocentric coordinate system into the relative coordinate system to obtain the landmark coordinates in the relative coordinate system; Converting the landmark coordinates in the relative coordinate system into the northeast celestial coordinate system to obtain the landmark coordinates in the northeast celestial coordinate system; Convert the landmark coordinates in the northeast celestial coordinate system into the inertial navigation coordinate system to obtain the landmark coordinates in the inertial navigation coordinate system; The converted azimuth angle and the converted elevation angle are calculated using the landmark coordinates in the inertial navigation coordinate system.

5. The method for calibrating the installation error between the inertial navigation system and the optoelectronic payload based on the landmark according to claim 4 is characterized in that: The longitude of the spatial geodetic coordinate system is the angle between the spatial point and the plane where the rotation axis of the reference ellipsoid is located and the starting meridian plane of the reference ellipsoid. The latitude of the spatial geodetic coordinate system is the angle between the spatial point and the normal line of the reference ellipsoid surface and the equatorial plane. The altitude of the spatial geodetic coordinate system is the distance from the spatial point to the reference ellipsoid surface along the normal line direction of the reference ellipsoid. The position data of the landmark in the spatial geodetic coordinate system is (L d ,B d ,H d ) T , where T represents the transpose of the matrix; The origin of the geocentric coordinate system is the center of the reference ellipsoid. d The X axis of the reference ellipsoid coincides with the rotation axis of the reference ellipsoid, with the upward direction being positive. d The Y axis is the intersection of the Greenwich meridian plane and the Earth's equatorial plane, and is positive outward. d The axis is in the equatorial plane and is aligned with the X d Axis and Z d The axes form a right-handed coordinate system; The calculation formula of the landmark coordinates in the geocentric coordinate system is: Among them, g x X represents the geocentric coordinate system d Axis landmark coordinates, g y Y represents the geocentric coordinate system d Axis landmark coordinates, g z Z represents the geocentric coordinate system d The coordinates of the axis landmark, H d Indicates the height of the landmark, B d Indicates the latitude of the landmark, L d Indicates the longitude of the landmark, a represents the equatorial radius of the earth, b represents the polar radius of the earth, and the coordinates of the landmark in the geocentric coordinate system are (g x ,g y ,g z ) T .

6. The method for calibrating the installation error between the inertial navigation system and the optoelectronic payload based on the landmark according to claim 5 is characterized in that: The relative coordinate system is a three-dimensional rectangular coordinate system independently defined to realize the conversion from the northeast celestial coordinate system to the geocentric coordinate system. The origin of the relative coordinate system is the projection of the mass center of the inertial navigation on the surface of the earth. r The X axis of the geocentric coordinate system d The axes are parallel and in the same direction, and the Y r The Y axis of the geocentric coordinate system d The axes are parallel and in the same direction, and the Z r The Z axis of the geocentric coordinate system d The axes are parallel and in the same direction; The calculation formula of the landmark coordinates in the relative coordinate system is: Among them, (r x ,r y ,r z ) T Represents the landmark coordinates in the relative coordinate system, r x X represents the relative coordinate system r The coordinates of the axis landmark, r y Represents the Y of the relative coordinate system r The coordinates of the axis landmark, r z Represents the Z of the relative coordinate system r The coordinates of the axis landmarks, B represents the latitude of the inertial navigation system, and L represents the longitude of the inertial navigation system.

7. The method for calibrating the installation error between the inertial navigation system and the optoelectronic payload based on the landmark according to claim 6 is characterized in that: The origin of the northeast celestial coordinate system is the center of mass of the inertial navigation. G The axis points to the east, and the Y axis of the northeast celestial coordinate system G The axis points to due north, and the Z axis of the northeast celestial coordinate system G The axis points to the sky along the vertical line of the earth; The calculation formula of the landmark coordinates in the northeast celestial coordinate system is: Among them, (n x ,n y ,n z ) T Represents the landmark coordinates in the northeast celestial coordinate system, n x X represents the northeast celestial coordinate system G Axis landmark coordinates, n y Y represents the northeast celestial coordinate system G Axis landmark coordinates, n z Z represents the northeast celestial coordinate system G The landmark coordinates of the axis, H represents the height of the inertial navigation, represents the transformation matrix in the northeast sky coordinate system, 8. The method for calibrating the installation error between the inertial navigation system and the optoelectronic payload based on the landmark according to claim 7, characterized in that: The origin of the inertial navigation coordinate system is the center of mass of the inertial navigation, the X-axis of the inertial navigation coordinate system points to the horizontal axis of the installation plane of the inertial navigation, the Y-axis of the inertial navigation coordinate system points to the longitudinal axis of the installation plane of the inertial navigation, and the Z-axis of the inertial navigation coordinate system is perpendicular to the plane and points to the zenith, and forms a right-handed coordinate system with the X-axis and the Y-axis; The calculation formula of the landmark coordinates in the inertial navigation coordinate system is: Among them, (c x ,c y ,c z ) T represents the landmark coordinates in the inertial navigation coordinate system, c x represents the landmark coordinates of the X axis of the inertial navigation coordinate system, c y represents the Y-axis landmark coordinate of the inertial navigation coordinate system, c z Represents the landmark coordinates of the Z axis of the inertial navigation coordinate system, represents the transformation matrix in the inertial navigation coordinate system, θ represents the inertial navigation heading angle, ε represents the inertial navigation pitch angle, and γ represents the inertial navigation roll angle.

9. The method for calibrating the installation error between the inertial navigation system and the optoelectronic payload based on the landmark according to claim 8, characterized in that: The calculation formula of the conversion azimuth is: Among them, α2 represents the conversion azimuth; The calculation formula for the conversion pitch angle is: Among them, β2 represents the conversion pitch angle; The calculation formula of the azimuth error angle is: α ′ ＝α1-α2 (7) Among them, α ′ represents the azimuth error angle, α1 represents the initial azimuth angle; The calculation formula of the pitch error angle is: β ′ ＝β1-β2 (8) Among them, β ′ represents the pitch error angle, and β1 represents the initial pitch angle.

10. The method for calibrating the installation error between the inertial navigation system and the optoelectronic payload based on the landmark according to claim 9, characterized in that: The step of correcting the frame angle of the optoelectronic payload by using the azimuth error angle and the pitch error angle to complete the calibration operation includes: Measuring the corrected front position angle and the corrected front pitch angle of the frame angle by using an angle measuring sensor; Calculating a corrected azimuth angle of the frame angle using the azimuth error angle, and calculating a corrected pitch angle of the frame angle using the pitch error angle; The calculation formula of the corrected azimuth is: α 后 ＝α 前 -α ′ (9) Among them, α 后 represents the corrected azimuth of the frame angle, α 前 Indicates the corrected forward angle of the frame angle; The calculation formula of the corrected pitch angle is: β 后 ＝β 前 -β ′ (10) Among them, β 后 represents the corrected pitch angle of the frame angle, β 前 Indicates the corrected pitch angle of the frame angle.

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