A method for automatic correction of geotrack errors

Abstract

The present application relates to the technical field of pod, and discloses a kind of geographic tracking error automatic correction method, including the longitude and latitude high coordinate of calibration target point is obtained and input to photoelectric pod;Calibration target is locked in image center by ground station image tracking, and photoelectric pod receives error automatic correction instruction;Real-time calculation is carried out to the space guide angle between current pod and calibration target;When pod actual image locks calibration target, the current attitude angle is measured by inertial navigation in pod, and the error observation value of the point is calculated;N total error observation values corresponding to different space guide angles are continuously collected in smooth flight stage;System zero offset, scale factor error and nonlinear coefficient are obtained by using least square method, and it is stored;When executing geographic tracking task, the current space guide angle is calculated in real time, and the corresponding error prediction value is obtained to realize real-time correction.The present application continuously offsets time-varying error such as temperature drift and structural deformation by real-time data collection in flight, and precision no longer deteriorates with time.

Description

Technical Field

[0001] This invention relates to the field of pod technology, and in particular to an automatic correction method for geographic tracking errors. Background Technology

[0002] In electro-optical pods that require geographic tracking capabilities, many factors can affect the accuracy of the geographic tracking function, leading to errors that exceed the acceptable range. At high flight altitudes, large errors can even cause the target to leave the line-of-sight observation range, thus rendering the reconnaissance meaningless.

[0003] The main sources of error in existing optoelectronic pods are as follows: 1. Core errors of sensors: such as zero bias, scaling factor error, random walk, etc. of inertial measurement unit (IMU), which accumulate over time.

[0004] 2. Dynamic environmental errors: vibrations, impacts, and temperature changes caused by carrier movement.

[0005] 3. Installation errors between the pod and the aircraft or other carriers.

[0006] Existing technologies mainly employ the following two types of error control schemes: Ground-based mechanical precision machining + manual static calibration: By improving the flatness of the installation surface and manually measuring the installation error angle and fixing it into the pod navigation computer, it is impossible to compensate for time-varying errors caused by temperature gradients, airframe deflection, and shock absorber creep during flight. Moreover, the process is cumbersome and highly dependent on personnel skills.

[0007] Reliance on external high-precision auxiliary equipment: For example, using differential GPS for aerial calibration requires additional expensive equipment and has high requirements for weather and airspace, resulting in poor engineering practicality. Summary of the Invention

[0008] To solve the above problems, the technical solution adopted by the present invention is as follows: An automatic correction method for geographic tracking errors includes the following steps: S1. Obtain the latitude, longitude, and altitude coordinates of the calibration target point and input them into the photoelectric pod; S2. During flight, the image tracker of the optoelectronic pod locks the calibrated target to the center of the image through command control from the ground station, and the optoelectronic pod receives the error automatic correction command. S3. Calculate the spatial guidance angle A between the current pod and the calibration target in real time. i ; S4. When the actual image from the pod locks onto the calibrated target, the current attitude angle B is measured using the inertial navigation system within the pod. i And calculate the total error observation value C at that point. i =B i -Ai ; S5. During the stable flight phase, continuously collect N different spatial guidance angles A. i The corresponding C i Forming N groups (A) i C i )data; S6. Substitute the N sets of data into the fitting model equation A i =Δ bias +Δ scale ·A i +k2·A i ², the zero bias Δ of the system is obtained by solving using the least squares method. bias , Scale factor error Δ scale and the nonlinear coefficient k2; S7. The calculated Δ bias Δ scale k2 is stored in the Flash memory of the optoelectronic pod MCU; S8. When performing a geographic tracking task, calculate the current spatial guidance angle A in real time. i The corresponding error prediction value C is obtained by calling the fitted model equation. i And subtract the C when controlling the servo steering angle. i This enables real-time correction of geographic tracking errors.

[0009] Furthermore, N ≥ 30, and the N groups (A) i C i The data is evenly distributed in both azimuth and elevation dimensions.

[0010] Furthermore, the stable flight phase is defined as a root mean square value of the aircraft acceleration being less than 0.05g and a duration greater than 60s.

[0011] Furthermore, after step S6, the process further includes: setting the Δ bias Δ scale The k2 parameter is transmitted back to the ground station via the telemetry link for validity verification. If the verification fails, the current calculation result is discarded and data is collected again.

[0012] Furthermore, the spatial guiding angle A i The line-of-sight vector is calculated by using the attitude angles output from the inertial navigation system inside the pod and the target geographic coordinates.

[0013] Furthermore, the Flash stores multiple sets of Δ bias Δ scale The k2 parameter, each group of parameters corresponds to a different temperature range, and the corresponding parameter is called according to the real-time temperature during geographic tracking.

[0014] The beneficial effects of this invention are: Dynamic error closed-loop compensation: By collecting data in real time during flight and updating the model, time-varying errors such as temperature drift and structural deformation are continuously offset, and the accuracy no longer deteriorates over time.

[0015] No human intervention required: The entire process is completed automatically, avoiding human measurement errors and reducing reliance on operator skills.

[0016] It has good mission compatibility: it can be calibrated using natural or cooperative targets during normal flight without the need for dedicated airspace or additional equipment.

[0017] High statistical reliability: The least squares fitting of a large sample of N≥30 points is used to effectively suppress random interference such as image noise and IMU random drift. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0019] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0020] An automatic correction method for geographic tracking errors includes the following steps: S1. Obtain the latitude, longitude, and altitude coordinates of the calibration target point and input them into the photoelectric pod; S2. During flight, the image tracker of the optoelectronic pod locks the calibrated target to the center of the image through command control from the ground station, and the optoelectronic pod receives the error automatic correction command. S3. Calculate the spatial guidance angle A between the current pod and the calibration target in real time. i ; S4. When the actual image from the pod locks onto the calibrated target, the current attitude angle B is measured using the inertial navigation system within the pod. iAnd calculate the total error observation value C at that point. i =B i -A i ; S5. During the stable flight phase, continuously collect N different spatial guidance angles A. i The corresponding C i Forming N groups (A) i C i )data; S6. Substitute the N sets of data into the fitting model equation A i =Δ bias +Δ scale ·A i +k2·A i ², the zero bias Δ of the system is obtained by solving using the least squares method. bias , Scale factor error Δ scale and the nonlinear coefficient k2; S7. The calculated Δ bias Δ scale k2 is stored in the Flash memory of the optoelectronic pod MCU; S8. When performing a geographic tracking task, calculate the current spatial guidance angle A in real time. i The corresponding error prediction value C is obtained by calling the fitted model equation. i And subtract the C when controlling the servo steering angle. i This enables real-time correction of geographic tracking errors.

[0021] Specifically, N ≥ 30, and the N groups (A) i C i The data is evenly distributed in both azimuth and elevation dimensions.

[0022] Specifically, the stable flight phase is defined as a period in which the root mean square value of the aircraft's acceleration is less than 0.05g and the duration is greater than 60s.

[0023] Specifically, after step S6, the process further includes: setting the Δ bias Δ scale The k2 parameter is transmitted back to the ground station via the telemetry link for validity verification. If the verification fails, the current calculation result is discarded and data is collected again.

[0024] Specifically, the spatial guiding angle A i The line-of-sight vector is calculated by using the attitude angles output from the inertial navigation system inside the pod and the target geographic coordinates.

Claims

1. A method for automatically correcting geographic tracking errors, characterized in that: Includes the following steps: S1. Obtain the latitude, longitude, and altitude coordinates of the calibration target point and input them into the photoelectric pod; S2. During flight, the image tracker of the optoelectronic pod locks the calibrated target to the center of the image through command control from the ground station, and the optoelectronic pod receives the error automatic correction command. S3. Calculate the spatial guidance angle A between the current pod and the calibration target in real time. i ; S4. When the actual image from the pod locks onto the calibrated target, the current attitude angle B is measured using the inertial navigation system within the pod. i And calculate the total error observation value C at that point. i =B i -A i ; S5. During the stable flight phase, continuously collect N different spatial guidance angles A. i The corresponding C i Forming N groups (A) i C i )data; S6. Substitute the N sets of data into the fitting model equation A i =Δ bias +Δ scale ·A i +k2·A i ², the zero bias Δ of the system is obtained by solving using the least squares method. bias , Scale factor error Δ scale and the nonlinear coefficient k2; S7. The calculated Δ bias Δ scale k2 is stored in the Flash memory of the optoelectronic pod MCU; S8. When performing a geographic tracking task, calculate the current spatial guidance angle A in real time. i The corresponding error prediction value C is obtained by calling the fitted model equation. i And subtract the C when controlling the servo steering angle. i This enables real-time correction of geographic tracking errors.

2. The method for automatic correction of geographic tracking errors according to claim 1, characterized in that: The N≥30, and the N groups (A) i C i The data is evenly distributed in both azimuth and elevation dimensions.

3. The method for automatic correction of geographic tracking errors according to claim 2, characterized in that: The stable flight phase is defined as a period in which the root mean square value of the aircraft's acceleration is less than 0.05g and the duration is greater than 60s.

4. The method for automatic correction of geographic tracking errors according to claim 3, characterized in that: Following step S6, the process further includes: setting the Δ bias Δ scale The k2 parameter is transmitted back to the ground station via the telemetry link for validity verification. If the verification fails, the current calculation result is discarded and data is collected again.

5. The method for automatic correction of geographic tracking errors according to claim 4, characterized in that: The spatial guiding angle A i The line-of-sight vector is calculated by using the attitude angles output from the inertial navigation system inside the pod and the target geographic coordinates.

6. The method for automatic correction of geographic tracking errors according to claim 5, characterized in that: Multiple sets of Δ are stored in the Flash memory. bias Δ scale The k2 parameter, each group of parameters corresponds to a different temperature range, and the corresponding parameter is called according to the real-time temperature during geographic tracking.