Memory tracking method for three-axis three-frame photoelectric holder

Abstract

The invention belongs to the technical field of automation control, and particularly relates to a memory tracking method for a three-axis three-frame photoelectric holder. The method comprises the following steps: S1, enabling the visual axis of a three-axis three-frame photoelectric holder to point to a target, tracking the target by using the three-axis three-frame photoelectric holder, and calculating the movement speed of the target in a geographic coordinate system; s2, judging whether a target tracked by the three-axis three-frame photoelectric holder is shielded or not, if yes, executing the step S3, and if not, executing the step S4; s3, calculating an orientation guide angular rate and a pitching guide angular rate of the three-axis three-frame photoelectric holder based on the movement speed of the target under the geographic coordinate system, and realizing memory tracking of the target; and S4, judging whether the tracking task continues to be executed or not, if so, executing the step S1, and otherwise, ending the tracking task for the tracking target. According to the invention, memory tracking is carried out when the target is lost, so that the photoelectric holder can automatically capture and track the target again when the 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 three-axis three-frame photoelectric pan / tilt platform. Background Art

[0002] The three-axis three-frame optoelectronic gimbal realizes the functions of inertial space stabilization and tracking by rotating around the azimuth, pitch, and roll axes. When the three-axis three-frame optoelectronic gimbal tracks the target, its roll axis is always in a stable state to eliminate the disturbance in the rolling direction of the carrier, while the azimuth axis and pitch axis respond to the tracker's miss amount to realize the automatic tracking function of the target. The three-axis three-frame 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 three-axis three-frame optoelectronic pan-tilt head to solve the problem that the prior art cannot perform memory tracking on the target. The present invention performs memory tracking when the target is lost, so that when the target reappears, the optoelectronic 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 three-axis three-frame photoelectric gimbal comprises the following steps: S1: Make the visual axis of the three-axis three-frame optoelectronic gimbal point to the target, use the three-axis three-frame optoelectronic gimbal to track the target, and calculate the moving speed of the target in the geographic coordinate system; S2: Determine whether the target tracked by the three-axis three-frame optoelectronic gimbal 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 optoelectronic gimbal based on the target's motion speed in the geographic coordinate system, and realize memory tracking of the target until the visual axis of the three-axis three-frame optoelectronic gimbal is re-pointed to the tracking target; S4: Determine whether the tracking task is to be continued. If so, execute step S1; otherwise, terminate the tracking task for the tracking target.

[0005] Furthermore, step S1 specifically includes: 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; S12: The three-axis three-frame optoelectronic gimbal posture information, the carrier posture information, the carrier height and the target area height are used to calculate the straight-line distance L between the target and the carrier, and the velocity component of the target in the X direction of the visual axis coordinate system is calculated 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 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 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 carrier's velocity in the visual axis coordinate system , calculate the target's moving speed in the geographic coordinate system .

[0006] 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.

[0007] Furthermore, the target area height is the height of the projection point of the carrier on the ground.

[0008] 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 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.

[0009] Furthermore, 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 visual axis coordinate system : .

[0010] Furthermore, step S3 specifically includes the following steps: S31: According to the target's movement speed in the geographic coordinate system and the carrier's velocity in the visual axis coordinate system , calculate the velocity of the carrier relative to the target ; S32: Combined with the straight-line distance L, calculate the azimuth guidance angular velocity of the three-axis three-frame optoelectronic 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 measured by the three-axis three-frame optoelectronic gimbal.

[0011] Furthermore, the transformation matrix from the geographic coordinate system to the line of sight coordinate system is for:

[0012]

[0013] ; Among them, R is the roll angle measured by the three-axis three-frame optoelectronic gimbal, is the azimuth angle measured by the three-axis three-frame optoelectronic gimbal, is the pitch angle measured by the three-axis three-frame optoelectronic 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:

[0014]

[0015] .

[0016] Compared with the prior art, the invention can achieve the following beneficial effects: The present invention creates a memory tracking method for a three-axis three-frame optoelectronic pan-tilt, which calculates and memorizes the movement speed of a target when the three-axis three-frame optoelectronic pan-tilt is stably tracking. The target movement speed calculated by the present invention has higher real-time performance than a 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 target is lost due to occlusion or the like, the stored target movement speed is used to participate in the solution, and an azimuth velocity guidance value and a pitch velocity guidance value are obtained when the three-axis three-frame optoelectronic pan-tilt is lost in tracking the target, and the visual axis is guided 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 optoelectronic pan-tilt can quickly capture and re-track the target. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 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 flow chart of a memory tracking method for a three-axis three-frame photoelectric gimbal according to an embodiment of the present invention; Figure 2 A schematic diagram of the geographic coordinate system, carrier coordinate system and visual axis coordinate system described in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0023] The three-axis three-frame optoelectronic gimbal includes 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 installed on the pitch axis; the azimuth frame is driven by an azimuth motor, and the azimuth angle is measured by an azimuth encoder installed on the azimuth axis; the roll frame is driven by a roll motor, and the roll angle is measured by a roll encoder installed on the roll axis; the gyro uses a three-axis gyroscope, which is installed on the inner pitch frame to measure the rotation angular rate of the sensitive visual axis in the inertial space. When the three-axis three-frame optoelectronic gimbal is working normally, its roll frame is always in an inertial stable state, which is used to eliminate the rotation interference in the roll direction caused by the carrier; its azimuth frame and pitch frame respond to the off-target amount of the tracker in the tracking state, and can realize the automatic tracking function of the target.

[0024] like Figure 1-Figure 2As shown, the present invention proposes a memory tracking method for a three-axis three-frame optoelectronic gimbal, which specifically includes the following steps: S1: point the visual axis of the three-axis three-frame optoelectronic gimbal to the target, use the three-axis three-frame optoelectronic gimbal 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 optoelectronic gimbal is blocked, if so, execute step S3, otherwise execute step S4; S3: solve the azimuth guidance angular rate and pitch guidance angular rate of the three-axis three-frame optoelectronic gimbal based on the movement speed of the target in the geographic coordinate system, and realize memory tracking of the target until the visual axis of the three-axis three-frame optoelectronic gimbal points to the tracking target again; S4: determine whether the tracking task continues to be executed, if so, execute step S1, otherwise end the tracking task of the tracking target.

[0025] When the three-axis three-frame photoelectric pan-tilt is in stable tracking, the present invention estimates the movement speed of the target in the geographic coordinate system in real time and stores it in memory. When the target is lost due to occlusion or the like, the three-axis three-frame photoelectric pan-tilt uses the stored movement speed of the target to participate in the solution, and guides the visual axis of the three-axis three-frame photoelectric pan-tilt along the expected movement direction of the target, 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 can automatically capture and re-track the target.

[0026] In some examples, step S1 specifically includes: S11: the three-axis three-frame photoelectric gimbal 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 carrier's velocity in the visual axis coordinate system , calculate the target's moving speed in the geographic coordinate system .

[0027] 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.

[0028] Furthermore, the movement speed 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, so that when the target's movement direction remains unchanged, the target is always near the center of the field of view during the loss period.

[0029] 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 the inertial space.

[0030] In some examples, the target area height is the height of the projection point of the carrier on the ground.

[0031] 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 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.

[0032] In some examples, 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 visual axis coordinate system : .

[0033] In some examples, S31: according to the moving speed of the target in the geographic coordinate system and the carrier's velocity in the visual axis coordinate system , calculate the velocity of the carrier relative to the target ; S32: Combined with the straight-line distance L, calculate the azimuth guidance angular velocity of the three-axis three-frame optoelectronic 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 measured by the three-axis three-frame optoelectronic gimbal.

[0034] It should be noted that the target's movement speed in the geographic coordinate system The speed of the carrier in the geographic coordinate system Superposition to obtain the velocity of the carrier relative to the target .

[0035] Furthermore, the carrier is usually a drone, and the carrier has the function of obtaining the height of the target area.

[0036] 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 carrier's center of gravity as the origin, the positive direction of the X axis is toward the north along the local longitude, the positive direction of the Y axis is toward the east along the local latitude, and the positive direction of the Z axis is toward the center of the earth along the vertical line; 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 from the carrier 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 taken as 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 and the direction 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 visual axis coordinate system via the carrier coordinate system and its inverse transformation. In the figure, 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.

[0037] Transformation matrix from geographic coordinate system to line of sight coordinate system for:

[0038]

[0039] ; Among them, R is the roll angle measured by the three-axis three-frame optoelectronic gimbal, is the azimuth angle measured by the three-axis three-frame optoelectronic gimbal, is the pitch angle measured by the three-axis three-frame optoelectronic 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:

[0040]

[0041] .

[0042] In the stage of automatically tracking the target, the present invention uses the target area height given by the carrier 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 according to the straight-line distance The rate of change of the target in the X direction of the visual axis coordinate system is obtained by .

[0043] 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.

[0044] 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 three-axis three-frame photoelectric PTZ, characterized in that: The specific steps include: S1: Make the visual axis of the three-axis three-frame optoelectronic gimbal point to the target, use the three-axis three-frame optoelectronic gimbal to track the target, and calculate the moving speed of the target in the geographic coordinate system; S2: Determine whether the target tracked by the three-axis three-frame optoelectronic gimbal 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 moving speed of the target in the geographic coordinate system, so as to realize the memory tracking of the target until the visual axis of the three-axis three-frame optoelectronic gimbal is re-pointed to the tracking target; S4: Determine whether the tracking task is to be continued. If so, execute step S1; otherwise, terminate the tracking task for the tracking target.

2. The memory tracking method for a three-axis three-frame photoelectric PTZ according to claim 1, characterized in that: Step S1 specifically includes: S11: The three-axis three-frame photoelectric gimbal is placed on a 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: The three-axis three-frame optoelectronic gimbal posture information, the carrier posture information, the carrier height and the target area height are used to calculate the straight-line distance L between the target and the carrier, and the velocity component of the target in the X direction of the visual axis coordinate system is calculated 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 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 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 carrier's velocity in the visual axis coordinate system , calculate the target's moving speed in the geographic coordinate system .

3. The memory tracking method for a three-axis three-frame photoelectric PTZ according to claim 2, 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.

4. The memory tracking method for a three-axis three-frame photoelectric PTZ according to claim 2, characterized in that: The target area height is the height of the projection point of the carrier on the ground.

5. 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 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.

6. 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 visual axis coordinate system : 。 7. 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 carrier's velocity in the visual axis coordinate system , calculate the velocity of the carrier relative to the target ; S32: Combined with the straight-line distance L, calculate the azimuth guidance angular velocity of the three-axis three-frame optoelectronic 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 measured by the three-axis three-frame optoelectronic gimbal.

8. The memory tracking method for a three-axis three-frame optoelectronic 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 optoelectronic gimbal, is the azimuth angle measured by the three-axis three-frame optoelectronic gimbal, is the pitch angle measured by the three-axis three-frame optoelectronic 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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