Memory tracking method for two-axis optoelectronic pan / tilt

Abstract

The present application belongs to the field of automation control technology, and particularly relates to a memory tracking method for a two-axis photoelectric pan-tilt.S1: fixing the two-axis photoelectric pan-tilt on a carrier;S2: stably tracking the tracking target by using a stable tracking mode, and calculating the movement speed of the tracking target in a geographic coordinate system;S3: judging whether the tracking target is in an occluded state in the tracking process of the two-axis photoelectric pan-tilt, if yes, executing step S4, otherwise, executing step S5;S4: inversely calculating the azimuth guide angular velocity and the pitch guide angular velocity of the two-axis photoelectric pan-tilt, realizing the memory tracking of the tracking target, until the boresight of the two-axis photoelectric pan-tilt points to the tracking target again;S5: judging whether the tracking task is continued to execute, if yes, executing step S2, otherwise, ending the tracking task of the tracking target.The present application carries out memory tracking when the tracking target is lost, so as to automatically capture and re-track the target when the tracking target reappears.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of automation control, and particularly relates to a memory tracking method for a two-axis photoelectric gimbal. BACKGROUND

[0002] The two-axis two-frame photoelectric gimbal realizes the functions of inertial space stabilization and tracking by rotating around the azimuth axis and the pitch axis. The photoelectric gimbal is usually installed on a flying vehicle such as a UAV and a manned aircraft, and is used for observing the ground target and continuously tracking and measuring the target of interest. In the process of tracking the target, the photoelectric gimbal often appears the phenomenon that the tracking target is lost due to being blocked by clouds, mountains and buildings, etc. When the tracking target reappears, the tracking target deviates from the center of the field of view of the photoelectric gimbal by a large angle, and when the carrier and the tracking target have relative motion, the deviation angle will be larger, and even may exceed the current field of view of the photoelectric gimbal, resulting in tracking failure. SUMMARY

[0003] Therefore, the present application aims to provide a memory tracking method for a two-axis photoelectric gimbal to solve the problem that the prior art cannot perform memory tracking on the tracking target. The present application performs memory tracking when the tracking target is lost, so that the photoelectric gimbal can automatically capture and re-track the target when the tracking target reappears.

[0004] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0005] A memory tracking method for a two-axis photoelectric gimbal, specifically comprising the following steps:

[0006] S1: fixing the two-axis photoelectric gimbal on a carrier, taking the center of gravity of the carrier as the origin , establishing a geographical coordinate system, a line-of-sight coordinate system and a carrier coordinate system which satisfy the right-hand rule;

[0007] S2: the line-of-sight of the two-axis photoelectric gimbal points to the tracking target, and the tracking target is stably tracked in a stable tracking mode, and the motion speed of the tracking target in the geographical coordinate system is calculated based on the carrier information and the tracking target information ;

[0008] S3: judging whether the tracking target is in a blocked state in the tracking process of the two-axis photoelectric gimbal, if yes, executing step S4, otherwise, executing step S5;

[0009] S4: based on the motion speed of the tracking target in the geographical coordinate system obtained in step S2 , inversely calculating the azimuth guide angular velocity and the pitch guide angular velocity of the two-axis photoelectric gimbal, realizing memory tracking of the tracking target, until the line-of-sight of the two-axis photoelectric gimbal re-points to the tracking target;

[0010] S5: determining whether the tracking task is continued to be executed, if yes, executing step S2, otherwise ending the tracking task of the tracking target.

[0011] Further, step S2 specifically comprises the following steps:

[0012] S21: calculating a distance L between the tracking target and the carrier according to the azimuth angle and the elevation angle of the two-axis photoelectric gimbal, the attitude information of the carrier, the height of the carrier and the height of the target region, and calculating a velocity component of the tracking target in the X direction of the visual axis coordinate system according to the change rate of the distance L ;

[0013] S22: measuring an angular velocity of the visual axis in the inertial space by using the gyroscope of the two-axis photoelectric gimbal, and calculating a velocity component of the tracking target in the Y direction of the visual axis coordinate system and a velocity component of the tracking target in the Z direction of the visual axis coordinate system ;

[0014] S23: calculating a motion velocity of the carrier relative to the tracking target in the visual axis coordinate system based on the velocity component , the velocity component and the velocity component ; ;

[0015] S24: transforming the motion velocity of the carrier relative to the tracking target in the visual axis coordinate system to the geographic coordinate system, and combining the motion velocity of the carrier in the visual axis coordinate system to calculate a motion velocity of the tracking target in the geographic coordinate system .

[0016] Further, in step S21, the height of the target region is the height of the carrier at the ground projection point.

[0017] Further, in step S22, the angular velocity of the visual axis in the inertial space ; wherein, is an angular velocity component of the angular velocity in the X direction of the visual axis coordinate system, is an angular velocity component of the angular velocity in the Y direction of the visual axis coordinate system, is an angular velocity component of the angular velocity in the Z direction of the visual axis coordinate system.

[0018] Further, in step S22, the velocity component of the tracking target in the Y direction of the visual axis coordinate system is calculated as follows:

[0019] ;

[0020] Calculate the velocity component of the tracking target in the Z direction of the line-of-sight coordinate system :

[0021] .

[0022] Further, step S4 specifically comprises:

[0023] S41: According to the motion speed of the tracking target in the geographic coordinate system and the motion speed of the carrier , calculate the motion speed of the carrier relative to the tracking target ;

[0024] S42: In combination with the distance L, calculate the azimuth guide angular velocity of the two-axis photoelectric PTZ in the Y axis direction of the line-of-sight coordinate system and the pitch guide angular velocity in the axis direction :

[0025] ;

[0026] ;

[0027] Wherein, is the velocity component of the motion speed in the Y direction, is the velocity component of the motion speed in the Z direction, and E is the pitch angle.

[0028] Further, in step S41, the motion speed of the tracking target in the geographic coordinate system is superimposed with the motion speed of the carrier in the geographic coordinate system to obtain the motion speed of the carrier relative to the tracking target .

[0029] Further, the carrier comprises a UAV.

[0030] Compared with the prior art, the present application can achieve the following beneficial effects:

[0031] The present invention creates a memory tracking method for a two-axis photoelectric pan-tilt platform, which calculates and stores the movement speed of the tracking target when the two-axis 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 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 photoelectric pan-tilt platform loses the tracking target 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 photoelectric pan-tilt platform can quickly capture and re-track the target. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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:

[0033] Figure 1 This is a schematic structural diagram of a two-axis photoelectric pan / tilt platform according to an embodiment of the present invention;

[0034] Figure 2 A flow chart of a memory tracking method for a two-axis photoelectric pan / tilt head according to an embodiment of the present invention;

[0035] Figure 3 The invention creates a process for calculating the motion speed of a tracking target in the stable tracking mode described in an embodiment of the invention;

[0036] Figure 4 This invention creates a process for calculating the motion speed of a tracking target in the memory tracking mode described in an embodiment of the invention;

[0037] Figure 5 Schematic diagram of the geographic coordinate system, carrier coordinate system and line of sight coordinate system described in the embodiment of the present invention.

[0038] Description of reference numerals:

[0039] 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

[0040] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not constitute a limitation on the present application.

[0041] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0042] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only used for description purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0043] In the description of the present application, it should be noted that unless otherwise specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0044] The present application will be described in detail below with reference to the drawings and embodiments.

[0045] As Figure 1As shown, the two-axis optoelectronic pan-tilt head includes an azimuth angle measuring element 1, a base 2, a pitch motor 3, a pitch frame 4, an optical payload 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 payload 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 payload 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 used to measure the pitch angle and azimuth angle of the visual axis, respectively. The gyroscope 6 uses a three-axis gyroscope 6, which is installed on the pitch frame 4 to measure the rotational angular velocity of the visual axis in inertial space.

[0046] like Figure 2 As shown, the present invention proposes a memory tracking method for a two-axis photoelectric pan-tilt platform, which specifically includes the following steps: S1: fix the two-axis photoelectric pan-tilt platform on the 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 using the 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 photoelectric PTZ. 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 velocity and pitch guidance angular velocity of the two-axis optoelectronic pan-tilt platform to realize memory tracking of the tracking target 13 until the visual axis of the two-axis optoelectronic pan-tilt platform 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.

[0047] The optoelectronic pan-tilt platform has inertial space stabilization and automatic tracking functions. When the two-axis optoelectronic pan-tilt platform is in stable tracking mode, the present invention estimates the speed of the tracking target 13 in the geographic coordinate system in real time and stores it in memory. If the tracking target 13 is lost due to occlusion or other reasons, the two-axis optoelectronic pan-tilt platform uses the stored speed of the tracking target 13 to participate in the solution, guiding the two-axis optoelectronic pan-tilt platform's visual axis to move along the expected direction of the tracking target 13, ensuring that the tracking target 13 is near the center of the field of view during the running time of the tracking task. When the tracking target 13 reappears, the two-axis optoelectronic pan-tilt platform can automatically capture and re-track the target 13.

[0048] In some instances, such as Figure 3As shown, step S2 specifically includes the following steps: S21: according to the azimuth and pitch angles of the two-axis photoelectric platform, the attitude information of the carrier 12 (yaw angle , pitch angle , roll angle ), the height of the carrier 12 and the target area height 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: using the two-axis photoelectric gyroscope 6 to measure the angular velocity of the visual axis in the inertial space, and based on the angular velocity of the visual axis in the inertial space, respectively calculate the velocity component of the tracking target 13 in the Y direction of the visual axis coordinate system and the velocity component in the Z direction ; S23: Based on velocity component , velocity component and velocity components , calculate the velocity of the carrier 12 relative to the tracking target 13 in the visual axis coordinate system ; S24: The velocity of the carrier 12 relative to the tracking target 13 in the visual axis coordinate system Transform to the geographic coordinate system and combine 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 .

[0049] 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.

[0050] Furthermore, the speed of movement When stored in the carrier 12 and used to memorize the tracking mode, the azimuth guidance angular velocity and the pitch guidance angular velocity 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.

[0051] In some examples, in step S21 , the target area height is the height of the projection point of the carrier 12 on the ground.

[0052] It should be noted that the target area height of the tracking target 13 is acquired by the carrier 12 .

[0053] 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.

[0054] 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. :

[0055] ;

[0056] Calculate the velocity component of the tracking target 13 in the Z direction of the visual axis coordinate system :

[0057] .

[0058] 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 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 platform in the Y-axis direction of the visual axis coordinate system and Pitch guidance angular velocity in the axis direction :

[0059] ;

[0060] ;

[0061] in, Movement speed The velocity component in the Y direction, Movement speed The velocity component in the Z direction, E is the pitch angle.

[0062] It should be noted that, in step S41, the moving speed of the tracking target 13 in the geographic coordinate system is The movement speed of the carrier 12 in the geographic coordinate system Superposition, obtain the movement speed of the carrier 12 relative to the tracking target 13 .

[0063] In some examples, vehicle 12 includes a drone.

[0064] It should be noted that the carrier 12 has the function of obtaining the height of the target area.

[0065] like Figure 5 As shown, the following describes the geographic coordinate system, the carrier coordinate system and the visual axis coordinate system. The three take the center of gravity of the carrier 12 as the origin. Construct a coordinate system that satisfies the right-hand rule, geographic coordinate system :Use the north direction as the positive direction of the X axis of the geographic coordinate system, the east direction 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 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 pointing to the target along the visual axis 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, 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 conversion of the geographic coordinate system through the carrier coordinate system to the visual axis 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.

[0066] The transformation matrix from the geographic coordinate system to the line of sight coordinate system is as follows:

[0067] ;

[0068] in, is the yaw angle, is the pitch angle, is the roll angle, E is the pitch angle, and A is the azimuth angle.

[0069] Its inverse transformation matrix is ​​as follows:

[0070] .

[0071] 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.

[0072] The foregoing detailed description has set forth various embodiments of the devices and / or processes via the use of specific terminology. However, embodiments thereof can be practiced with the exact description not being presented in detail. The term "device" should be understood to encompass devices operating in various modes, such as active mode, sleep mode, hibernate mode, and the like. The terms "coupled" and "connected," along with their derivatives, can be used. It should be understood that these terms are not intended as synonyms for each other. Rather, particular circuitry that can be said to be coupled or connected can be coupled and connected via some transmission medium.

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 PTZ 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; S2: The two-axis photoelectric PTZ points its visual axis to the tracking target, and uses a stable tracking mode to stably track the tracking target, and calculates the movement speed of the tracking target in the geographic coordinate system based on the carrier information and the tracking target information. ; Step S2 specifically includes the following steps: S21: Calculate the distance L between the tracking target and the carrier based on 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 based on 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 velocity of the carrier in the visual axis coordinate system relative to the tracking target Transform to the geographic coordinate system and combine it 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 ; S3: Determine whether the tracking target is in an obstructed state during the tracking process of the two-axis optoelectronic pan / tilt head. 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 velocity and the pitch guidance angular velocity 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; Step S4 specifically includes: S41: The speed of the target being tracked 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, Movement speed The velocity component in the Y direction, Movement speed The velocity component in the Z direction, E is the pitch angle; S5: Determine whether the tracking task is to continue. If so, execute step S2; otherwise, terminate the tracking task for the target.

2. The memory tracking method for a two-axis photoelectric PTZ according to claim 1, 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.

3. 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.

4. The memory tracking method for a two-axis photoelectric PTZ according to claim 3, 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 : 。 5. The memory tracking method for a two-axis photoelectric PTZ according to claim 1, characterized in that: In step S41, the moving speed of the tracking target in the geographic coordinate system is The movement speed of the carrier in the geographic coordinate system Superposition to obtain the velocity of the carrier relative to the tracking target .

6. 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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