Photoelectric pod air target correction method based on target information

Abstract

The invention relates to a photoelectric pod air target correction method based on target information, which comprises the following steps: before an aircraft takes off, measuring the geographic position of a selected target point, after the aircraft enters an airline, observing and aiming a target in the intervals of 0-90 degrees, 90-180 degrees,-90-0 degree and-180--90 degrees of the azimuth of a photoelectric pod respectively, and after the aircraft enters the airline, observing and aiming the target in the intervals of 0-90 degrees, 90-180 degrees,-90-0 degree and-180--90 degrees of the azimuth of the photoelectric pod; the current inertial navigation information and the GPS geographic position are recorded at each observation point through a ground snapshot instruction, target correction acquisition point collection is completed after target observation of each azimuth angle under each quadrant is completed, the installation deviation angle of the photoelectric pod and the aircraft inertial navigation is calculated, the installation deviation angle is written into a pod EEPROM to be stored, and the installation deviation angle of the photoelectric pod and the aircraft inertial navigation is obtained. In a word, the method is suitable for all ground station systems and airplanes with air boresight conditions, and has the advantages of low cost, short time, convenience in use and capability of ensuring the correction precision of the installation deviation angle.

Description

Technical Field

[0001] The invention belongs to the technical field of inertial guidance of an optoelectronic pod, and in particular relates to an air target calibration method for an optoelectronic pod based on target information. Background Art

[0002] The optoelectronic pod is a high-precision reconnaissance device that integrates visible light, infrared, and laser. It can perform mission operations, reconnaissance and strike functions around the clock. In order to achieve rapid and accurate search and strike of targets, optoelectronic pods are generally equipped with geo-positioning and geo-tracking functions, so inertial navigation component attitude information and GPS signals are required as information input. For example, when performing geo-tracking tasks, the angle information of the target relative to the pod can be calculated based on the input target GPS coordinates and real-time airborne attitude information, thereby achieving rapid pointing of the optoelectronic aiming line, facilitating rapid detection of targets in the pod image, and achieving geo-positioning by calculating the target's geographical location through laser ranging. Therefore, only with high positioning and geo-tracking accuracy as the basis can accurate reconnaissance intelligence be obtained, targets can be quickly locked, and timely damage can be achieved.

[0003] Current UAV flight platforms are generally equipped with high-precision inertial navigation components installed on the aircraft fuselage, while the optoelectronic pod is installed under the belly of the aircraft and fixed to the aircraft by an adapter plate bracket. As a result, there will be an unpredictable installation deviation angle between the aircraft inertial navigation component and the optoelectronic pod, which in turn affects the positioning accuracy of the optoelectronic pod.

[0004] In order to solve this problem, most aircraft currently use the method of leveling the aircraft for ground calibration, and make a calibration diagram of the relative aiming line center of the optoelectronics and the aircraft according to the structural visual axis of the optoelectronics and the aircraft, and place the target at a horizontal position 10m away from the aircraft. When the aircraft axis and the optoelectronic aiming line simultaneously point to the center of the target's own aiming line, it is considered that the position at this time is the zero position of the optoelectronic pod, and the calibration is completed, that is, the installation deviation angle of the aircraft and the optoelectronic pod has been eliminated; however, this method will consume a lot of manpower, material resources and time, and the final alignment of the aiming line is achieved by the human eye, and the accuracy of the installation deviation angle correction cannot be guaranteed. Therefore, an aerial calibration technology is designed, which can achieve high-precision installation deviation angle correction by a single operator, thereby solving the above-mentioned problems. Summary of the invention

[0005] The present invention provides an aerial target calibration method for an optoelectronic pod based on target information. According to the existing interface form of the ground station, the method can be directly embedded in the ground station equipment after being programmed into software. The method can be applicable to all unmanned aerial vehicles equipped with a ground station, and the technical problems that ground target calibration requires a lot of manpower, material resources and time and the accuracy of installation deviation angle correction cannot be guaranteed are solved.

[0006] In order to achieve the above technical objectives, the specific technical solutions adopted by the present invention are:

[0007] 1. An air calibration method for an optoelectronic pod based on target information, comprising the following steps:

[0008] S1. Before the aircraft takes off, measure the geographical location of the selected target point;

[0009] S2. After the aircraft enters the route, it observes and aims at the target in the ranges of 0°~90°, 90°~180°, -90°~0°, and -180°~-90° of the optoelectronic pod, and records the current inertial navigation information and GPS geographical location at each observation and aiming point through ground snapshot commands;

[0010] S3. After the target observation and aiming at each azimuth in each quadrant is completed, the target collection points are collected and the installation deviation angle between the optoelectronic pod and the aircraft inertial navigation is calculated;

[0011] S4. Write the installation deviation angle into the pod EEPROM for storage.

[0012] Furthermore, in step S1, before the aircraft takes off, the geographical location of the selected target point is measured by a handheld GPS.

[0013] Furthermore, in step S1, the optoelectronic pod aligns its own zero scale lines in the azimuth and pitch directions according to the mechanical structure provided by the aircraft, so that the zero position of the optoelectronic pod is kept consistent with the nose of the aircraft.

[0014] Furthermore, in step S2, when the optoelectronic pod is observing and aiming, it first searches for the calibrated target, operates the optoelectronic pod to search and observe the target, and tracks the target. If it cannot be tracked, it searches for the calibrated target again, takes an inertial navigation information snapshot of the tracked target, and if the current point value is available, it is recorded, otherwise the point information is rolled back.

[0015] Furthermore, in step S3, the installation deviation angle calculation process is as follows:

[0016] S501, set the heading deviation angle between the optoelectronic pod and the aircraft inertial navigation component to h, the pitch deviation angle to p, and the roll deviation angle to;

[0017] S502, respectively assuming the three deviation angles, and substituting them into the target positioning algorithm equations in sections, geographically locating the same target at different snapshot points, and recalculating the target geographical location;

[0018] S503. By comparing with the actual geographical location of the known target measured in advance, a point with the minimum error is obtained. The corresponding deviation angle at this time is the optimal assumed angle, which is used as the aerial target calibration value.

[0019] Furthermore, the error caused by the measurement deviation of the laser rangefinder is corrected according to the result of step S503, and the distance between the laser rangefinder and the target point is used as the slant distance used in the geolocation algorithm to convert the positions of the two points in the earth coordinate system into the XYZ coordinates of the spatial rectangular coordinate system. The correction process is as follows:

[0020] S601, assuming the position of the optoelectronic pod is (X P ,Y P ,Z P ), the actual position of the calibration point is (X T ,Y T ,Z Z ), then the slope distance is

[0021]

[0022] S602, traverse within the range of ±3° of the three attitude angles in a cyclic manner, and the first round of traversal is performed with an accuracy of 0.1°. At each test point, the traversal deviation angle is substituted into the target position for solution, and the distance deviation is obtained by subtracting it from the calibration point, and the mean of multiple sampling points is calculated, and it is continuously compared with the mean solved under the previous assumed deviation point. The point with a smaller mean is retained as the comparison point for the next traversal, and the cycle is repeated, and finally the optimal deviation angle of heading, pitch, and roll with an accuracy of 0.1 can be obtained;

[0023] S603, based on the result of the previous step, further subdivide the accuracy to 0.01°, traverse in the same way, and finally obtain the optimal deviation angle of heading, pitch, and roll with an accuracy of 0.01°.

[0024] By adopting the above technical solution, the present invention can also bring the following beneficial effects:

[0025] 1. The present invention provides an airborne target calibration method for an optoelectronic pod based on target information. The inertial navigation component attitude information and GPS signal are used as information input. When performing geographic tracking tasks, the angle information of the target relative to the pod can be calculated according to the input target GPS coordinates combined with real-time airborne attitude information, thereby realizing rapid pointing of the optoelectronic aiming line, and quickly finding the target in the pod image. At the same time, the target geographical location is calculated by laser ranging to realize geographic positioning. The calibration speed is fast and can be completed in only 10 to 15 minutes, saving time.

[0026] 2. The present invention mentions an aerial target calibration method for an optoelectronic pod based on target information. It does not need to level the aircraft on the ground, which is time-consuming and labor-intensive, and does not take up extra flight sorties. If the optoelectronic pod is not disassembled, the calibration value will always be applicable to all subsequent flight missions, which can save costs and be recycled. At the same time, the corresponding algorithm can be transplanted to other types of optoelectronic products, and the aerial target calibration software can also be embedded in other types of UAV ground stations. It has versatility and universality, and has very good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a flow chart of an aerial target calibration method of an optoelectronic pod based on target information of the present invention;

[0029] Figure 2 The invention discloses an aerial target calibration route diagram of an optoelectronic pod aerial target calibration method based on target information. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0032] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present invention, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0033] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention. The drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0034] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.

[0035] Example 1

[0036] In one embodiment of the present invention, see Figure 1 and Figure 2 , an optoelectronic pod aerial target calibration method based on target positioning, comprising the following steps:

[0037] 1. When the optoelectronic pod is powered on and the aircraft takes off, the optoelectronic pod should first align its own zero scale lines in the azimuth and pitch directions according to the mechanical structure provided by the aircraft, so that the zero position of the optoelectronic pod is consistent with the nose of the aircraft. Before takeoff, hold the GPS information to confirm the target for aerial calibration.

[0038] 2. The aircraft enters a fixed route.

[0039] 3. Search and mark the target. After the aircraft takes off and enters the route, the target is searched and sighted in the optoelectronic pod azimuth ranges of 0°~90°, 90°~180°, -90°~0°, and -180°~-90°.

[0040] 4. Track the target. If it cannot be tracked, search for the calibration target again. If it is because geographic tracking cannot enter the small field of view, change the field of view and click Track.

[0041] 5. Snapshot the inertial navigation information at the current moment. At this time, take a snapshot of the inertial navigation information of the tracked target and make a judgment. If the current point value is available, record it.

[0042] 6. If the current point value is not available, roll back the sampling point information and take a snapshot of the inertial navigation information.

[0043] 7. Take multi-point snapshots of inertial navigation information. When the target observation in each azimuth in each quadrant is completed, the collection of target calibration points is completed.

[0044] 8. Solve the aerial target calibration results and calculate the installation deviation angle between the optoelectronic pod and the aircraft inertial navigation.

[0045] The solution process is as follows:

[0046] Assume that the heading deviation angle between the optoelectronic pod and the aircraft inertial navigation component is h, the pitch deviation angle is p, and the roll deviation angle is r. Generally, the deviation angle caused by manual installation will not be too large (the empirical angle is within ±3°). Therefore, the three deviation angles are assumed in a traversal manner and are substituted into the target positioning algorithm equation piece by piece. The same target is geographically located at different snapshot points, and the target geographical location is recalculated; by comparing with the known target's real geographical location measured in advance, a point with the smallest error is obtained. At this time, the corresponding deviation angle is the optimal assumed angle, which can be used as the aerial target calibration value.

[0047] In order to eliminate the error caused by the measurement deviation of the laser rangefinder, the distance between the machine and the target point is used as the slant distance used in the geolocation algorithm, that is, the positions of the two points in the earth coordinate system are converted into the XYZ coordinates of the spatial rectangular coordinate system.

[0048] Assume that the position of the optoelectronic pod is (X P ,Y P ,Z P ), the actual position of the calibration point is (X T ,Y T ,Z T ), then the slope distance:

[0049]

[0050] Traverse the three attitude angles within the range of ±3° in a loop. The first round of traversal is performed with an accuracy of 0.1°. Substitute the traversal deviation angle into the target position solution at each test point, and subtract it from the calibration point to obtain the distance deviation, and calculate the average of multiple sampling points, and continuously compare it with the average calculated under the previous assumed deviation point. The point with a smaller average is left as the comparison point for the next traversal; in this cycle, the optimal deviation angle of heading, pitch, and roll with an accuracy of 0.1 can be obtained in the end.

[0051] Based on the result of the previous step, the accuracy is further subdivided to 0.01°. The traversal is repeated in the same way. Finally, the optimal installation deviation angle of heading, pitch, and roll with an accuracy of 0.01° can be obtained.

[0052] Finally, the installation deviation angle is written into the pod EEPROM for storage.

[0053] According to the existing interface forms of different ground station seats, the present invention can form optoelectronic pod target positioning aerial target calibration software after software programming, which is directly embedded in the ground station software. It is suitable for all ground station systems and aircraft with aerial target calibration conditions, and has the advantages of low cost, short time, easy use and ability to ensure the accuracy of installation deviation angle correction.

[0054] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An optoelectronic pod aerial target calibration method based on target information, characterized in that: The following steps are involved: S1. Before the aircraft takes off, measure the geographical location of the selected target point; S2. After the aircraft enters the route, it observes and aims at the target in the ranges of 0°~90°, 90°~180°, -90°~0°, and -180°~-90° of the optoelectronic pod, and records the current inertial navigation information and GPS geographical location at each observation and aiming point through ground snapshot commands; S3. After the target observation and aiming at each azimuth in each quadrant is completed, the target collection points are collected and the installation deviation angle between the optoelectronic pod and the aircraft inertial navigation is calculated; S4. Write the installation deviation angle into the pod EEPROM for storage.

2. The method for air calibration of an optoelectronic pod based on target information according to claim 1 is characterized in that: In step S1, before the aircraft takes off, the geographical location of the selected target point is measured by a handheld GPS.

3. The method for air calibration of an optoelectronic pod based on target information according to claim 2 is characterized in that: In step S1, the optoelectronic pod aligns its own zero scale lines in the azimuth and pitch directions according to the mechanical structure provided by the aircraft, so that the zero position of the optoelectronic pod is consistent with the direction of the aircraft nose.

4. The method for air calibration of an optoelectronic pod based on target information according to claim 3 is characterized in that: In step S2, when the optoelectronic pod is observing and aiming, it first searches for the calibration target, operates the optoelectronic pod to search and observe the target, and tracks the target. If it cannot be tracked, it searches for the calibration target again, and takes an inertial navigation information snapshot of the tracked target. If the current point value is available, it is recorded, otherwise the point information is rolled back.

5. The method for air calibration of an optoelectronic pod based on target information according to claim 4 is characterized in that: In step S3, the installation deviation angle calculation process is as follows: S501, setting the heading deviation angle between the optoelectronic pod and the aircraft inertial navigation component to h, the pitch deviation angle to p, and the roll deviation angle to r; S502, respectively assuming the three deviation angles, and substituting them into the target positioning algorithm equations in sections, geographically locating the same target at different snapshot points, and recalculating the target geographical location; S503. By comparing with the real geographical location of the known target measured in advance, a point with the smallest positioning solution error is obtained. The corresponding deviation angle at this time is the optimal assumed angle, which is used as the aerial target calibration value.

6. The method for air calibration of an optoelectronic pod based on target information according to claim 5 is characterized in that: Based on the result of step S503, the error caused by the measurement deviation of the laser rangefinder is corrected, and the distance between the machine and the target point is used as the slant distance used in the geolocation algorithm. The positions of the two points in the earth coordinate system are converted into the XYZ coordinates of the spatial rectangular coordinate system. The correction process is as follows: S601, assuming the position of the optoelectronic pod is (X P ,Y P ,Z P ), the actual position of the calibration point is (X T ,Y T ,Z T ), then the slope distance is S602, traverse within the range of ±3° of the three attitude angles in a cyclic manner, and the first round of traversal is performed with an accuracy of 0.1°. At each test point, the traversal deviation angle is substituted into the target position for solution, and the distance deviation is obtained by subtracting it from the calibration point, and the mean of multiple sampling points is calculated, and it is continuously compared with the mean solved under the previous assumed deviation point. The point with a smaller mean is retained as the comparison point for the next traversal, and the cycle is repeated, and finally the optimal deviation angles of heading, pitch, and roll with an accuracy of 0.1 can be obtained; S603, based on the result of step S602, further subdivide the result to 0.01°, and traverse in the same way to finally obtain the optimal deviation angles of heading, pitch, and roll with an accuracy of 0.01°.

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