Memory tracking method for two-axis photoelectric holder

Abstract

The invention belongs to the technical field of automatic control, and particularly relates to a memory tracking method for a two-axis photoelectric holder. The method comprises the following steps: S1, fixing a two-axis photoelectric holder on a carrier; s2, performing stable tracking on the tracking target by adopting a stable tracking mode, and calculating the movement speed # imgabs0 # of the tracking target under the geographic coordinate system; s3, judging whether the tracked target is in a shielded state in the tracking process of the two-axis photoelectric holder, if so, executing the step S4, and otherwise, executing the step S5; s4, the azimuth guide angular rate and the pitching guide angular rate of the two-axis photoelectric holder are solved reversely, and memory tracking of the tracking target is achieved until the visual axis of the two-axis photoelectric holder points to the tracking target again; and S5, judging whether the tracking task continues to be executed or not, if so, executing the step S2, and otherwise, ending the tracking task for the tracking target. According to the invention, memory tracking is carried out when the tracking target is lost, so that the target can be automatically captured and re-tracked when the tracking target appears again.

Description

Technical Field

[0001] The invention belongs to the technical field of automatic control, and in particular relates to a memory tracking method for a two-axis photoelectric pan / tilt platform. Background Art

[0002] The two-axis two-frame optoelectronic gimbal realizes the functions of inertial space stabilization and tracking by rotating around the azimuth axis and the pitch axis. The optoelectronic gimbal is usually installed on aircraft such as drones and manned aircraft to observe ground targets and continuously track and measure targets of interest. In the process of tracking targets, the optoelectronic gimbal often loses the tracking target due to obstruction by clouds, mountains, and buildings. When the tracking target reappears, the tracking target will deviate from the center of the field of view of the optoelectronic gimbal by a large angle. When the carrier and the tracking target have relative motion, the deviation angle will be even greater, and may even exceed the field of view of the current optoelectronic gimbal, causing tracking failure. Summary of the invention

[0003] In view of this, the present invention aims to provide a memory tracking method for a two-axis photoelectric pan-tilt head to solve the problem that the prior art cannot perform memory tracking on the tracking target. The present invention performs memory tracking when the tracking target is lost, so that when the tracking target reappears, the photoelectric pan-tilt head can automatically capture and re-track the target.

[0004] To achieve the above object, the technical solution created by the present invention is implemented as follows: A memory tracking method for a two-axis photoelectric gimbal comprises the following steps: S1: Fix the two-axis photoelectric gimbal on the carrier, taking the center of gravity of the carrier as the origin. , establish the geographic coordinate system, line of sight coordinate system and carrier coordinate system that satisfy the right-hand rule; S2: The two-axis optoelectronic gimbal points its sight axis to the target, and uses the stable tracking mode to stably track the target. The moving speed of the target in the geographic coordinate system is calculated based on the carrier information and the target information. ; S3: Determine whether the tracking target is in an obstructed state during the tracking process of the two-axis optoelectronic gimbal. If so, execute step S4; otherwise, execute step S5; S4: The moving speed of the tracking target in the geographic coordinate system obtained in step S2 , reversely solve the azimuth guidance angular rate and pitch guidance angular rate of the two-axis optoelectronic gimbal to realize the memory tracking of the tracking target until the visual axis of the two-axis optoelectronic gimbal points to the tracking target again; S5: Determine whether the tracking task is to be continued. If so, execute step S2; otherwise, terminate the tracking task for the tracking target.

[0005] Furthermore, step S2 specifically includes the following steps: S21: Calculate the distance L between the tracking target and the carrier according to the azimuth and pitch angles of the two-axis optoelectronic gimbal, the carrier's attitude information, the carrier's height and the target area height, and calculate the velocity component of the tracking target in the X direction of the visual axis coordinate system according to the rate of change of the distance L. ; S22: Use the gyroscope of the two-axis photoelectric gimbal to measure the angular velocity of the line of sight in the inertial space, and calculate the velocity component of the tracking target in the Y direction of the line of sight coordinate system based on the angular velocity of the line of sight in the inertial space. and the velocity component in the Z direction ; S23: Based on velocity components , velocity component and velocity components , calculate the velocity of the carrier relative to the tracking target in the visual axis coordinate system ; S24: The moving speed of the carrier in the visual axis coordinate system relative to the tracking target Transform to geographic coordinate system and combine with the carrier's movement speed in the line of sight coordinate system , calculate the moving speed of the tracking target in the geographic coordinate system .

[0006] Further, in step S21, the height of the target area is the height of the projection point of the carrier on the ground.

[0007] Further, in step S22, the angular velocity of the visual axis in the inertial space ;in, is the angular velocity component of the angular velocity in the X direction of the visual axis coordinate system, is the angular velocity component in the Y direction of the visual axis coordinate system, is the angular velocity component in the Z direction of the visual axis coordinate system.

[0008] Further, in step S22, the velocity component of the tracking target in the Y direction of the visual axis coordinate system is calculated. : ; Calculate the velocity component of the tracking target in the Z direction of the line of sight coordinate system : .

[0009] Furthermore, step S4 specifically includes: S41: According to the movement speed of the tracking target in the geographic coordinate system and the carrier's speed , calculate the velocity of the carrier relative to the tracking target ; S42: Combined with the distance L, calculate the azimuth guidance angular velocity of the two-axis photoelectric gimbal in the Y-axis direction of the visual axis coordinate system and Pitch guidance angular velocity in the axis direction : ; ; in, For the movement speed The velocity component in the Y direction, For the movement speed The velocity component in the Z direction, E is the pitch angle.

[0010] Further, in step S41, the moving speed of the tracking target in the geographic coordinate system is The speed of the carrier in the geographic coordinate system Superposition to obtain the velocity of the carrier relative to the tracking target .

[0011] Furthermore, the carrier includes a drone.

[0012] Compared with the prior art, the invention can achieve the following beneficial effects: The present invention creates a memory tracking method for a two-axis optoelectronic pan-tilt, which calculates and stores the movement speed of the tracking target when the two-axis optoelectronic pan-tilt is stably tracking. The target movement speed calculated by the present invention has higher real-time performance than the traditional target movement speed calculation method whose refresh rate is limited by the GPS refresh rate, and is suitable for use in a servo system. When the tracking target is lost, the stored target movement speed is used to participate in the solution, and the azimuth velocity guidance value and the pitch angular velocity guidance value when the two-axis optoelectronic pan-tilt is lost are obtained, and the visual axis is guided to move along the movement direction of the tracking target, ensuring that the target is always near the center of the field of view during the period of loss. When the tracking target reappears in the field of view, the two-axis optoelectronic pan-tilt can quickly capture and re-track the target. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 A schematic diagram of the structure of a two-axis photoelectric pan / tilt platform according to an embodiment of the present invention; Figure 2A flow chart of a memory tracking method for a two-axis photoelectric pan / tilt head according to an embodiment of the present invention; Figure 3 The present invention creates a motion speed calculation process for the tracking target in the stable tracking mode described in the embodiment; Figure 4 The present invention creates a process for calculating the motion speed of a tracking target in the memory tracking mode described in an embodiment of the present invention; Figure 5 A schematic diagram of the geographic coordinate system, carrier coordinate system and visual axis coordinate system described in an embodiment of the present invention.

[0014] Description of reference numerals: 1. Azimuth angle measurement element; 2. Base; 3. Pitch motor; 4. Pitch frame; 5. Optical payload; 6. Gyroscope; 7. Pitch axis; 8. Pitch angle measurement element; 9. Azimuth frame; 10. Azimuth axis; 11. Azimuth motor; 12. Carrier; 13. Tracking target. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0016] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0017] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0018] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0019] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0020] like Figure 1 As shown, the two-axis optoelectronic gimbal includes an azimuth angle measuring element 1, a base 2, a pitch motor 3, a pitch frame 4, an optical load 5, a gyroscope 6, a pitch axis 7, a pitch angle measuring element 8, an azimuth frame 9, an azimuth axis 10, and an azimuth motor 11. The pitch motor 3 drives the pitch axis 7 to rotate, and the pitch axis 7 drives the pitch frame 4 to rotate to adjust the pitch angle of the optical load 5 placed inside the pitch frame 4. The azimuth motor 11 drives the azimuth axis 10 to rotate, and the azimuth axis 10 drives the azimuth frame 9 to rotate to adjust the azimuth angle of the optical load 5 placed inside the pitch frame 4. The azimuth frame 9 is arranged on the outside of the pitch frame 4. The pitch angle measuring element 8 and the azimuth angle measuring element 1 are respectively used to measure the pitch angle and azimuth angle of the visual axis. The gyroscope 6 adopts a three-axis gyroscope 6, which is installed on the pitch frame 4 to measure the rotation angular rate of the visual axis in the inertial space.

[0021] like Figure 2 As shown, the present invention proposes a memory tracking method for a two-axis photoelectric pan-tilt, which specifically includes the following steps: S1: fix the two-axis photoelectric pan-tilt on a carrier 12, with the center of gravity of the carrier 12 as the origin , establish the geographic coordinate system, the line of sight coordinate system and the carrier coordinate system that satisfy the right-hand rule; S2: the line of sight of the two-axis optoelectronic gimbal points to the tracking target 13, the tracking target 13 is stably tracked in a stable tracking mode, and the movement speed of the tracking target 13 in the geographic coordinate system is calculated based on the carrier information and the tracking target 13 information ; S3: Determine whether the tracking target 13 is in an obstructed state during the tracking process of the two-axis optoelectronic gimbal. If so, execute step S4; otherwise, execute step S5; S4: The movement speed of the tracking target 13 in the geographic coordinate system obtained in step S2 , reversely solve the azimuth guidance angular rate and pitch guidance angular rate of the two-axis optoelectronic gimbal to realize memory tracking of the tracking target 13 until the visual axis of the two-axis optoelectronic gimbal points to the tracking target 13 again; S5: determine whether the tracking task continues to be executed, if so, execute step S2, otherwise end the tracking task of the tracking target 13.

[0022] The photoelectric pan-tilt has an inertial space stabilization function and an automatic tracking function. When the two-axis photoelectric pan-tilt is in a stable tracking mode, the present invention estimates the movement speed of the tracking target 13 in the geographic coordinate system in real time and stores it in memory. When the tracking target 13 is lost due to occlusion or other reasons, the two-axis photoelectric pan-tilt uses the stored movement speed of the tracking target 13 to participate in the solution, guides the two-axis photoelectric pan-tilt visual axis to move along the expected movement direction of the tracking target 13, ensures that the tracking target 13 is near the center of the field of view during the running time of the tracking task, and when the tracking target 13 reappears, the two-axis photoelectric pan-tilt can automatically capture and re-track the target 13.

[0023] In some instances, such as Figure 3 As shown, step S2 specifically includes the following steps: S21: according to the azimuth and pitch angles of the two-axis optoelectronic gimbal, the attitude information of the carrier 12 (yaw angle , Pitch angle , Roll Angle ), the height of the carrier 12 and the height of the target area calculate the distance L between the tracking target 13 and the carrier 12, and calculate the velocity component of the tracking target 13 in the X direction of the visual axis coordinate system according to the change rate of the distance L S22: Use the gyroscope 6 of the two-axis photoelectric gimbal to measure the angular velocity of the visual axis in the inertial space, and calculate the velocity component of the tracking target 13 in the Y direction of the visual axis coordinate system based on the angular velocity of the visual axis in the inertial space and the velocity component in the Z direction ; S23: Based on velocity component , velocity component and velocity components , calculate the moving speed of the carrier 12 relative to the tracking target 13 in the visual axis coordinate system ; S24: The moving speed of the carrier 12 relative to the tracking target 13 in the visual axis coordinate system Transformed to the geographic coordinate system, and combined with the movement speed of the carrier 12 in the line of sight coordinate system , calculate the moving speed of the tracking target 13 in the geographic coordinate system .

[0024] It should be noted that the movement speed of the carrier refers to the movement speed of the carrier itself in the geographic coordinate system, and the specific value is given by the inertial navigation on the carrier. The movement speed of the target refers to the movement speed of the target itself in the geographic coordinate system. In the same coordinate system, if the speeds of both are known and both are vectors, the difference between the two is the movement speed of the carrier relative to the target.

[0025] Furthermore, the movement speed When stored in the carrier 12 and used to memorize the tracking mode, the azimuth guidance angular rate and the pitch guidance angular rate of the two-axis optoelectronic pan-tilt platform are reversely solved, so that the pitch motor 3 and the azimuth motor 11 guide the visual axis to move along the movement direction of the tracking target 13 according to the solved value, thereby ensuring that when the movement direction of the tracking target 13 remains unchanged, the tracking target 13 is always maintained near the center of the field of view, and when the tracking target 13 reappears, the two-axis optoelectronic pan-tilt platform will automatically capture and re-track the target 13.

[0026] In some examples, in step S21 , the target area height is the height of the projection point of the carrier 12 on the ground.

[0027] It should be noted that the target area height of the tracking target 13 is acquired by the carrier 12 .

[0028] In some examples, in step S22, the angular velocity of the visual axis in the inertial space is ;in, is the angular velocity component of the angular velocity in the X direction of the visual axis coordinate system, is the angular velocity component in the Y direction of the visual axis coordinate system, is the angular velocity component in the Z direction of the visual axis coordinate system.

[0029] In some examples, in step S22, the velocity component of the tracking target 13 in the Y direction of the visual axis coordinate system is calculated. : ; Calculate the velocity component of the tracking target 13 in the Z direction of the visual axis coordinate system : .

[0030] In some instances, such as Figure 4 As shown, step S4 specifically includes: S41: according to the movement speed of the tracking target 13 in the geographic coordinate system and the movement speed of the carrier 12 , calculate the moving speed of the carrier 12 relative to the tracking target 13 ; S42: Combined with the distance L, calculate the azimuth guidance angular velocity of the two-axis photoelectric gimbal in the Y-axis direction of the visual axis coordinate system and Pitch guidance angular velocity in the axis direction : ; ; in, For the movement speed The velocity component in the Y direction, For the movement speed The velocity component in the Z direction, E is the pitch angle.

[0031] It should be noted that, in step S41, the moving speed of the tracking target 13 in the geographic coordinate system is The moving speed of the carrier 12 in the geographic coordinate system Superposition, obtain the moving speed of carrier 12 relative to tracking target 13 .

[0032] In some examples, vehicle 12 includes a drone.

[0033] It should be noted that the carrier 12 has the function of obtaining the height of the target area.

[0034] like Figure 5 As shown, the geographic coordinate system, the carrier coordinate system and the visual axis coordinate system are described below. The three systems take the center of gravity of the carrier 12 as the origin. Construct a coordinate system that satisfies the right-hand rule, the geographic coordinate system : The north direction is taken as the positive direction of the X axis of the geographic coordinate system, the east direction is taken as the positive direction of the Y axis of the geographic coordinate system, and the line connecting the origin and the center of the earth is taken as the positive direction of the Z axis; carrier coordinate system : The flight direction of the carrier 12 is taken as the positive direction of the X axis of the carrier coordinate system, the direction perpendicular to the cross section of the carrier 12 and pointing to the right side of the carrier is taken as the positive direction of the Y axis of the carrier coordinate system, and the direction pointing directly below the carrier 12 is taken as the positive direction of the Z axis of the carrier coordinate system. The direction along the visual axis pointing to the target is the positive direction of the X axis of the visual axis coordinate system, perpendicular to The direction pointing to the right is the positive direction of the Y axis of the visual axis coordinate system, which is perpendicular to The plane formed and the direction pointing downward is the positive direction of the Z axis of the visual axis coordinate system. The coordinate transformation involved in the present invention mainly involves the transformation of the geographic coordinate system to the visual axis coordinate system via the carrier coordinate system and its inverse transformation. Figure 3 In is the distance from the carrier 12 to the target, is the moving speed of the carrier 12, The target's movement speed.

[0035] The transformation matrix from the geographic coordinate system to the line of sight coordinate system is as follows: ; in, is the yaw angle, is the pitch angle, is the roll angle, E is the pitch angle, and A is the azimuth angle.

[0036] Its inverse transformation matrix is ​​as follows: .

[0037] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0038] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A memory tracking method for a two-axis photoelectric PTZ, characterized in that: The specific steps include: S1: Fix the two-axis photoelectric gimbal on the carrier, taking the center of gravity of the carrier as the origin. , establish the geographic coordinate system, line of sight coordinate system and carrier coordinate system that satisfy the right-hand rule; S2: The visual axis of the two-axis optoelectronic gimbal points to the tracking target, the tracking target is stably tracked in a stable tracking mode, and the movement speed of the tracking target in the geographic coordinate system is calculated based on the carrier information and the tracking target information. ; S3: Determine whether the tracking target is in an obstructed state during the tracking process of the two-axis optoelectronic gimbal. If so, execute step S4; otherwise, execute step S5; S4: The moving speed of the tracking target in the geographic coordinate system obtained in step S2 , reversely solving the azimuth guidance angular rate and the pitch guidance angular rate of the two-axis optoelectronic gimbal to realize memory tracking of the tracking target until the visual axis of the two-axis optoelectronic gimbal is re-pointed to the tracking target; S5: Determine whether the tracking task is to be continued. If so, execute step S2; otherwise, terminate the tracking task for the tracking target.

2. The memory tracking method for a two-axis photoelectric PTZ according to claim 1, characterized in that: Step S2 specifically includes the following steps: S21: Calculate the distance L between the tracking target and the carrier according to the azimuth and pitch angles of the two-axis optoelectronic gimbal, the carrier's attitude information, the carrier's height and the target area height, and calculate the velocity component of the tracking target in the X direction of the visual axis coordinate system according to the rate of change of the distance L. ; S22: Use the gyroscope of the two-axis photoelectric gimbal to measure the angular velocity of the line of sight in the inertial space, and calculate the velocity component of the tracking target in the Y direction of the line of sight coordinate system based on the angular velocity of the line of sight in the inertial space and the velocity component in the Z direction ; S23: Based on velocity components , velocity component and velocity components , calculate the velocity of the carrier relative to the tracking target in the visual axis coordinate system ; S24: The moving speed of the carrier in the visual axis coordinate system relative to the tracking target Transform to geographic coordinate system and combine with the carrier's movement speed in the line of sight coordinate system , calculate the moving speed of the tracking target in the geographic coordinate system .

3. The memory tracking method for a two-axis photoelectric PTZ according to claim 2, characterized in that: In step S21, the height of the target area is the height of the projection point of the carrier on the ground; the rate of change of the distance L is calculated at a time interval of 0.005 seconds.

4. The memory tracking method for a two-axis photoelectric PTZ according to claim 1, characterized in that: In step S22, the angular velocity of the visual axis in the inertial space is ;in, is the angular velocity component of the angular velocity in the X direction of the visual axis coordinate system, is the angular velocity component in the Y direction of the visual axis coordinate system, is the angular velocity component in the Z direction of the visual axis coordinate system.

5. The memory tracking method for a two-axis photoelectric PTZ according to claim 4, characterized in that: In step S22, the velocity component of the tracking target in the Y direction of the visual axis coordinate system is calculated. : ； Calculate the velocity component of the tracking target in the Z direction of the line of sight coordinate system : 。 6. The memory tracking method for a two-axis photoelectric PTZ according to claim 1, characterized in that: Step S4 specifically includes: S41: According to the movement speed of the tracking target in the geographic coordinate system and the carrier's speed , calculate the velocity of the carrier relative to the tracking target ; S42: Combined with the distance L, calculate the azimuth guidance angular velocity of the two-axis photoelectric gimbal in the Y-axis direction of the visual axis coordinate system and Pitch guidance angular velocity in the axis direction : ； ； in, For the movement speed The velocity component in the Y direction, For the movement speed The velocity component in the Z direction, E is the pitch angle.

7. The memory tracking method for a two-axis photoelectric PTZ according to claim 6, characterized in that: In step S41, the moving speed of the tracking target in the geographic coordinate system is The speed of the carrier in the geographic coordinate system Superposition to obtain the velocity of the carrier relative to the tracking target .

8. The memory tracking method for a two-axis photoelectric PTZ according to claim 1, characterized in that: The carriers include drones.

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