Memory tracking method for triaxial three-frame photoelectric pan-tilt

Abstract

The present application belongs to the field of automation control technology, and particularly relates to a memory tracking method for a three-axis three-frame photoelectric pan-tilt. The method comprises: S1: pointing the sight axis of the three-axis three-frame photoelectric pan-tilt to a target, tracking the target by the three-axis three-frame photoelectric pan-tilt, and calculating the movement speed of the target in a geographic coordinate system; S2: judging whether the target tracked by the three-axis three-frame photoelectric pan-tilt is blocked, if yes, executing step S3, otherwise executing step S4; S3: solving the azimuth guide angle rate and the pitch guide angle rate of the three-axis three-frame photoelectric pan-tilt based on the movement speed of the target in the geographic coordinate system, and realizing the memory tracking of the target; S4: judging whether the tracking task is continued to execute, if yes, executing step S1, otherwise ending the tracking task of the tracking target. The present application performs memory tracking when the target is lost, so that the photoelectric pan-tilt can automatically capture and re-track the target when the target reappears.

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 three-axis three-frame photoelectric platform. Background Art

[0002] A three-axis, three-gimbal optoelectronic gimbal achieves inertial space stabilization and tracking by rotating about its azimuth, pitch, and roll axes. When tracking a target, the gimbal maintains a stable roll axis, eliminating roll disturbances in the carrier. The azimuth and pitch axes automatically track the target based on the tracker's miss distance. Three-axis, three-gimbal optoelectronic gimbals are commonly installed on aircraft such as drones and manned aircraft to observe ground targets and continuously track and measure targets of interest. While tracking a target, the optoelectronic gimbal often loses track due to obstructions such as clouds, mountains, and buildings. When the target reappears, it deviates significantly from the gimbal's field of view. Relative motion between the carrier and the target increases this deviation, potentially exceeding the gimbal's field of view and causing tracking failure. Summary of the Invention

[0003] In view of this, the present invention aims to provide a memory tracking method for a three-axis three-frame photoelectric pan-tilt head to solve the problem that the existing technology cannot perform memory tracking of the target. The present invention performs memory tracking when the target is lost, so that when the 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:

[0005] A memory tracking method for a three-axis three-frame photoelectric pan / tilt platform comprises the following steps:

[0006] S1: Make the visual axis of the three-axis three-frame optoelectronic pan-tilt head point to the target, use the three-axis three-frame optoelectronic pan-tilt head to track the target, and calculate the target's movement speed in the geographic coordinate system;

[0007] S2: Determine whether the target tracked by the three-axis three-frame photoelectric pan-tilt head is blocked. If so, execute step S3; otherwise, execute step S4;

[0008] S3: Calculate the azimuth and elevation guidance angular rates of the three-axis three-frame electro-optical gimbal based on the target's motion velocity in the geographic coordinate system, and achieve target tracking until the three-axis three-frame electro-optical gimbal's line of sight is redirected to the target.

[0009] S4: Determine whether the tracking task is to continue. If so, execute step S1; otherwise, terminate the tracking task for the target.

[0010] Furthermore, step S1 specifically includes:

[0011] S11: The three-axis three-frame photoelectric gimbal is placed on the carrier, with 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;

[0012] S12: Calculate the straight-line distance L between the target and the carrier based on the attitude information of the three-axis three-frame optoelectronic gimbal, the attitude information of the carrier, the height of the carrier, and the height of the target area, and calculate the velocity component of the target in the X direction of the visual axis coordinate system based on the rate of change of the straight-line distance L. ;

[0013] S13: 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 of the three-axis three-frame optoelectronic gimbal in the inertial space and the velocity component in the Z direction ;

[0014] S14: Based on velocity components , velocity component and velocity components , calculate the velocity of the carrier relative to the target in the visual axis coordinate system , and the velocity of the carrier relative to the target Convert to geographic coordinate system;

[0015] S15: The speed of the carrier relative to the target based on the geographic coordinate system and the velocity of the carrier in the visual axis coordinate system , calculate the target's moving speed in the geographic coordinate system .

[0016] Furthermore, the gyroscope of the three-axis three-frame optoelectronic gimbal is used to measure the angular velocity of the visual axis of the three-axis three-frame optoelectronic gimbal in the inertial space.

[0017] Furthermore, the target area height is the height of the projection point of the carrier on the ground.

[0018] Furthermore, in step S13, 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 of the angular velocity in the Y direction of the visual axis coordinate system, is the angular velocity component in the Z direction of the line of sight coordinate system.

[0019] Furthermore, in step S13, the velocity component of the target in the Y direction of the visual axis coordinate system is calculated. :

[0020] ;

[0021] Calculate the target's velocity component in the Z direction of the line of sight coordinate system :

[0022] .

[0023] Furthermore, step S3 specifically includes the following steps:

[0024] S31: According to the target's movement speed in the geographic coordinate system and the velocity of the carrier in the visual axis coordinate system , calculate the velocity of the carrier relative to the target ;

[0025] S32: Calculate the azimuth guidance angular rate of the three-axis three-frame photoelectric gimbal in the Y-axis direction of the visual axis coordinate system based on the straight-line distance L and Pitch guidance angular velocity in the axis direction :

[0026] ;

[0027] ;

[0028] in, Movement speed The velocity component in the Y direction, Movement speed The velocity component in the Z direction, E is the pitch angle measured by the three-axis three-frame optoelectronic gimbal.

[0029] Furthermore, the transformation matrix from the geographic coordinate system to the line of sight coordinate system is for:

[0030]

[0031]

[0032] ;

[0033] Among them, R is the roll angle measured by the three-axis three-frame photoelectric gimbal, is the azimuth angle measured by the three-axis three-frame photoelectric gimbal, is the pitch angle measured by the three-axis three-frame photoelectric gimbal, is the yaw angle of the carrier, is the pitch angle of the carrier, is the rolling angle of the carrier;

[0034] Inverse transformation matrix for inverse transformation from geographic coordinate system to line of sight coordinate system for:

[0035]

[0036]

[0037] .

[0038] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0039] The present invention creates a memory tracking method for a three-axis three-frame photoelectric pan-tilt platform, which calculates and memorizes the target's movement speed when the three-axis three-frame photoelectric pan-tilt platform 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 frequency is limited by the GPS refresh speed, and is suitable for use in a servo system. When the target is lost due to occlusion or other reasons, the stored target movement speed is used to participate in the solution, and the azimuth velocity guidance value and pitch velocity guidance value when the three-axis three-frame photoelectric pan-tilt platform tracks the target when it is lost are obtained, guiding the visual axis to move along the expected movement direction of the target, ensuring that the target is always near the center of the field of view during the period of loss. When the target reappears in the field of view, the three-axis three-frame photoelectric pan-tilt platform can quickly capture and re-track the target. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0041] Figure 1 A flow chart of a memory tracking method for a three-axis three-frame photoelectric pan / tilt platform according to an embodiment of the present invention;

[0042] Figure 2 Schematic diagram of the geographic coordinate system, carrier coordinate system and line of sight coordinate system described in the embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0044] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0045] 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 orientations or positional relationships based on the orientations 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" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined as "first", "second" and the like 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.

[0046] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0047] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0048] The three-axis, three-frame optoelectronic gimbal consists of a pitch frame, an azimuth frame, and a roll frame. The pitch frame is driven by a pitch motor, and the pitch angle is measured by a pitch encoder mounted on the pitch axis. The azimuth frame is driven by an azimuth motor, and the azimuth angle is measured by an azimuth encoder mounted on the azimuth axis. The roll frame is driven by a roll motor, and the roll angle is measured by a roll encoder mounted on the roll axis. The gyro uses a three-axis gyroscope, mounted on the inner pitch frame, to measure the angular rate of rotation of the sensitive visual axis in inertial space. During normal operation, the roll frame of the three-axis, three-frame optoelectronic gimbal is always in an inertially stable state to eliminate rotational interference in the roll direction caused by the carrier. In the tracking state, the azimuth and pitch frames respond to the tracker's miss distance, enabling automatic target tracking.

[0049] like Figure 1-Figure 2As shown, the present invention proposes a memory tracking method for a three-axis three-frame photoelectric pan-tilt platform, which specifically includes the following steps: S1: point the visual axis of the three-axis three-frame photoelectric pan-tilt platform to the target, use the three-axis three-frame photoelectric pan-tilt platform to track the target, and calculate the movement speed of the target in the geographic coordinate system; S2: determine whether the target tracked by the three-axis three-frame photoelectric pan-tilt platform is blocked. If so, execute step S3, otherwise execute step S4; S3: calculate the azimuth guidance angular rate and pitch guidance angular rate of the three-axis three-frame photoelectric pan-tilt platform based on the movement speed of the target in the geographic coordinate system to achieve memory tracking of the target until the visual axis of the three-axis three-frame photoelectric pan-tilt platform points to the tracked target again; S4: determine whether the tracking task continues to be executed. If so, execute step S1, otherwise end the tracking task of the tracked target.

[0050] When the three-axis three-frame photoelectric pan-tilt platform is in stable tracking, the present invention estimates the target's movement speed in the geographic coordinate system in real time and stores it in memory. When the target is lost due to occlusion or other reasons, the three-axis three-frame photoelectric pan-tilt platform uses the stored target's movement speed to participate in the solution, and guides the three-axis three-frame photoelectric pan-tilt platform's visual axis to move along the target's expected movement direction, ensuring that the target is near the center of the field of view during the running time of the tracking task. When the target reappears, the three-axis three-frame photoelectric pan-tilt platform can automatically capture and re-track the target.

[0051] In some examples, step S1 specifically includes: S11: the three-axis three-frame photoelectric platform is placed on a carrier, with the center of gravity of the carrier as the origin , establish the geographic coordinate system, the line of sight coordinate system and the carrier coordinate system S12 that satisfy the right-hand rule: calculate the straight-line distance L between the target and the carrier based on the attitude information (azimuth and pitch angle) of the three-axis three-frame optoelectronic gimbal, the attitude information of the carrier, the height of the carrier and the height of the target area, and calculate the velocity component of the target in the X direction of the line of sight coordinate system based on the rate of change of the straight-line distance L (the rate of change of the distance L is calculated at a time interval of 0.005 seconds) ; S13: Calculate the velocity component of the tracking target in the Y direction of the visual axis coordinate system based on the angular velocity of the visual axis of the three-axis three-frame optoelectronic gimbal in the inertial space and the velocity component in the Z direction ; S14: Based on velocity component , velocity component and velocity components , calculate the velocity of the carrier relative to the target in the visual axis coordinate system , and the velocity of the carrier relative to the target Convert to geographic coordinate system; S15: The speed of the carrier relative to the target based on the geographic coordinate system and the velocity of the carrier in the visual axis coordinate system , calculate the target's moving speed in the geographic coordinate system .

[0052] It should be noted that the carrier's movement speed refers to the carrier's own movement speed in the geographic coordinate system, and the specific value is given by the inertial navigation on the carrier. The target's movement speed refers to the target's own movement speed 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 carrier's movement speed relative to the target.

[0053] Furthermore, the speed of movement When stored in the carrier for memory tracking, the azimuth guidance angular rate and pitch guidance angular rate of the two-axis optoelectronic gimbal are reversely solved, while the roll axis is always in a stable state, so that the pitch motor and azimuth motor guide the visual axis to move along the target's movement direction according to the solved value. Therefore, when the target's movement direction remains unchanged, the target is always near the center of the field of view during the loss period.

[0054] In some examples, a gyroscope of a three-axis three-frame optoelectronic gimbal is used to measure the angular velocity of the visual axis of the three-axis three-frame optoelectronic gimbal in an inertial space.

[0055] In some examples, the target area height is the height of the projection point of the carrier on the ground.

[0056] In some examples, in step S13, 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 of the angular velocity in the Y direction of the visual axis coordinate system, is the angular velocity component in the Z direction of the line of sight coordinate system.

[0057] In some examples, in step S13, the velocity component of the target in the Y direction of the visual axis coordinate system is calculated. :

[0058] ;

[0059] Calculate the target's velocity component in the Z direction of the line of sight coordinate system :

[0060] .

[0061] In some examples, S31: according to the moving speed of the target in the geographic coordinate system and the velocity of the carrier in the visual axis coordinate system , calculate the velocity of the carrier relative to the target ;

[0062] S32: Calculate the azimuth guidance angular rate of the three-axis three-frame photoelectric gimbal in the Y-axis direction of the visual axis coordinate system based on the straight-line distance L and Pitch guidance angular velocity in the axis direction :

[0063] ;

[0064] ;

[0065] in, Movement speed The velocity component in the Y direction, Movement speed The velocity component in the Z direction, E is the pitch angle measured by the three-axis three-frame optoelectronic gimbal.

[0066] It should be noted that the target's movement speed in the geographic coordinate system The movement speed of the carrier in the geographic coordinate system Superposition to obtain the velocity of the carrier relative to the target .

[0067] Furthermore, the carrier is usually a drone, and the carrier has the function of obtaining the height of the target area.

[0068] The present invention uses a relatively complex coordinate transformation function. In order to clearly describe the relevant functions of the present invention, the following conventions are made for the various coordinate systems of the present invention: Geographic coordinate system With the center of gravity of the carrier as the origin, the positive direction of the X axis is pointing north along the local longitude, the positive direction of the Y axis is pointing east along the local latitude, and the positive direction of the Z axis is pointing to the center of the earth along the vertical line; the carrier coordinate system Taking the center of gravity of the carrier as the origin, the positive direction of the X axis is along the carrier axis and points to the front of the carrier, the positive direction of the Y axis is perpendicular to the carrier reference plane and points to the right, and the positive direction of the Y axis is perpendicular to the carrier reference plane. The plane pointing downwards is the positive direction of the Z axis; the visual axis coordinate system With the visual axis rotation center as the origin, the direction perpendicular to the installation base and pointing to the target along the visual axis is the positive direction of the X axis. The direction pointing to the right is the positive direction of the Y axis, which is perpendicular to The plane formed by the coordinate system and pointing downward is the positive direction of the Z axis. The coordinate transformation involved in the present invention is mainly the transformation from the geographic coordinate system to the carrier coordinate system to the visual axis coordinate system and its inverse transformation. is the straight-line distance from the carrier to the target, is the velocity of the carrier in the geographic coordinate system, is the target's moving speed in the geographic coordinate system.

[0069] Transformation matrix from geographic coordinate system to line of sight coordinate system for:

[0070]

[0071]

[0072] ;

[0073] Among them, R is the roll angle measured by the three-axis three-frame photoelectric gimbal, is the azimuth angle measured by the three-axis three-frame photoelectric gimbal, is the pitch angle measured by the three-axis three-frame photoelectric gimbal, is the yaw angle of the carrier, is the pitch angle of the carrier, is the rolling angle of the carrier;

[0074] Inverse transformation matrix for inverse transformation from geographic coordinate system to line of sight coordinate system for:

[0075]

[0076]

[0077] .

[0078] The present invention uses the target area height given by the carrier to automatically track the target. and the carrier's own height information , combined with the roll angle R and azimuth angle measured by the angle measuring element and pitch angle , and the carrier's attitude information (yaw angle , pitch angle , roll angle ), calculate the straight-line distance between the target and the carrier in real time , and based on the straight-line distance The rate of change of the target in the X direction of the visual axis coordinate system is obtained by .

[0079] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0080] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A memory tracking method for a three-axis three-frame photoelectric PTZ, characterized by: The specific steps include: S1: Make the visual axis of the three-axis three-frame optoelectronic pan-tilt head point to the target, use the three-axis three-frame optoelectronic pan-tilt head to track the target, and calculate the target's movement speed in the geographic coordinate system; Step S1 specifically includes: S11: The three-axis three-frame photoelectric platform is placed on the carrier, with 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; S12: Calculate the straight-line distance L between the target and the carrier based on the attitude information of the three-axis three-frame optoelectronic gimbal, the attitude information of the carrier, the height of the carrier, and the height of the target area, and calculate the velocity component of the target in the X direction of the visual axis coordinate system based on the rate of change of the straight-line distance L. ; S13: 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 of the three-axis three-frame optoelectronic gimbal in the inertial space and the velocity component in the Z direction ; S14: Based on velocity components , velocity component and velocity components , calculate the velocity of the carrier relative to the target in the visual axis coordinate system , and the velocity of the carrier relative to the target Convert to geographic coordinate system; S15: The speed of the carrier relative to the target based on the geographic coordinate system and the velocity of the carrier in the visual axis coordinate system , calculate the target's moving speed in the geographic coordinate system ; S2: Determine whether the target tracked by the three-axis three-frame photoelectric pan-tilt head is blocked. If so, execute step S3; otherwise, execute step S4; S3: Calculating the azimuth guidance angular rate and the pitch guidance angular rate of the three-axis three-frame optoelectronic gimbal based on the target's motion velocity in the geographic coordinate system, thereby achieving target memory tracking until the three-axis three-frame optoelectronic gimbal's visual axis is redirected to the tracked target; S4: Determine whether the tracking task is to continue. If so, execute step S1; otherwise, terminate the tracking task for the target.

2. The memory tracking method for a three-axis three-frame photoelectric PTZ according to claim 1, characterized in that: The gyroscope of the three-axis three-frame optoelectronic gimbal is used to measure the angular velocity of the visual axis of the three-axis three-frame optoelectronic gimbal in the inertial space.

3. The memory tracking method for a three-axis three-frame photoelectric PTZ according to claim 1, characterized in that: The target area height is the height of the carrier's projection point on the ground.

4. The memory tracking method for a three-axis three-frame photoelectric PTZ according to claim 1, characterized in that: In step S13, 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 of the angular velocity in the Y direction of the visual axis coordinate system, is the angular velocity component in the Z direction of the line of sight coordinate system.

5. The memory tracking method for a three-axis three-frame photoelectric PTZ according to claim 1, characterized in that: In step S13, the velocity component of the target in the Y direction of the visual axis coordinate system is calculated. : ； Calculate the target's velocity component in the Z direction of the line of sight coordinate system : 。 6. The memory tracking method for a three-axis three-frame photoelectric PTZ according to claim 1, characterized in that: Step S3 specifically includes the following steps: S31: According to the target's movement speed in the geographic coordinate system and the velocity of the carrier in the visual axis coordinate system , calculate the velocity of the carrier relative to the target ; S32: Calculate the azimuth guidance angular rate of the three-axis three-frame photoelectric gimbal in the Y-axis direction of the visual axis coordinate system based on the straight-line distance L and Pitch guidance angular velocity in the axis direction : ； ； in, Movement speed The velocity component in the Y direction, Movement speed The velocity component in the Z direction, E is the pitch angle measured by the three-axis three-frame optoelectronic gimbal.

7. The memory tracking method for a three-axis three-frame photoelectric PTZ according to claim 1, characterized in that: Transformation matrix from geographic coordinate system to line of sight coordinate system for: ； Among them, R is the roll angle measured by the three-axis three-frame photoelectric gimbal, is the azimuth angle measured by the three-axis three-frame photoelectric gimbal, is the pitch angle measured by the three-axis three-frame photoelectric gimbal, is the yaw angle of the carrier, is the pitch angle of the carrier, is the rolling angle of the carrier; Inverse transformation matrix for inverse transformation from geographic coordinate system to line of sight coordinate system for: 。

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