Galvanometer control device and method for tracking and searching system

Abstract

The invention discloses a galvanometer control device and method for a tracking and searching system, and solves the problem that a staring compensation method of an existing infrared searching and tracking system does not have practicability and feasibility, so that a trailing phenomenon exists in a detected image, and the galvanometer control device specifically comprises a cavity of which the side wall is provided with a light window, the rotary table and the angle encoder are arranged outside the cavity, and the optical element, the galvanometer, the driving part, the detector and the numerical control unit are arranged in the cavity. By reasonably designing the swing scanning time of the galvanometer and controlling the time sequence of exposure of each frame of image, it is guaranteed that accurate image motion compensation is provided during periodic scanning of the azimuth rotary table, and target picture data are clear and free of trailing.

Description

Technical Field

[0001] The present invention relates to a compensation device and method, and particularly to a galvanometer control device and method for a tracking search system. Background Art

[0002] An infrared tracking search system uses the infrared characteristics of a detected target to identify and track it. Compared with the visible light band, the infrared band can identify targets at night or in low visibility conditions, and can be used for detecting and identifying low, small, and slow targets such as unmanned aerial vehicles. When the infrared tracking search system starts to search for a target, the optical imaging part will rotate around the azimuth axis and perform scanning imaging at a fixed rotational speed to achieve detection within a 360° range. Gaze compensation is a compensation technique for staring focal plane detectors. Since the characteristic of a staring detector is that its photosensitive element array is fixed and directly converts the received optical signal into an electrical signal, when the infrared tracking system is searching, the internal optical path direction needs to be adjusted; otherwise, the clarity of the detected image is poor and trailing phenomena will occur.

[0003] The Shanghai Institute of Technical Physics, Chinese Academy of Sciences proposed a galvanometer compensation control algorithm based on the M / T speed measurement algorithm in 2018, enabling effective image motion compensation during staring imaging even when the turntable undergoes arbitrary variable-speed motion during azimuth search. This algorithm only provides an algorithm for feedforward position closed-loop control of the galvanometer, making the speed under uniform motion remain consistent with the current turntable speed in real time, but it does not design how to generate each exposure signal from a system level or how to adjust the galvanometer scanning path when the turntable speed changes, and thus is not practical. The Shanghai Institute of Technical Physics, Chinese Academy of Sciences also proposed an image motion compensation method for a continuously zooming area array scanning optical system in 2023. This method only provides the ideal compensation angle of the galvanometer during image motion compensation for area array circumferential scanning of the infrared optical system, but does not propose a specific compensation implementation scheme and is not feasible. Summary of the Invention

[0004] To solve the technical problem that the existing gaze compensation methods for infrared search and tracking systems are not practical and feasible, resulting in trailing phenomena in the detected images, the present invention provides a galvanometer control device and method for a tracking search system.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A galvanometer control device for a tracking search system, characterized in that it includes a cavity with a light window on its side wall, a turntable and an angle encoder arranged outside the cavity, and an optical element, a galvanometer, a driving member, a detector, and a numerical control unit arranged inside the cavity;

[0007] Definition: The straight line where the rotation axis of the turntable is located is the Z-axis;

[0008] The rotating end of the turntable is connected to the cavity, and its signal input end is electrically connected to the numerical control unit, and is used to drive the cavity to rotate uniformly around the Z-axis according to the instructions of the numerical control unit;

[0009] The angle encoder is arranged on the rotation axis of the turntable and is electrically connected to the numerical control unit, and is used to measure the azimuth rotation angle of the turntable and send it to the numerical control unit;

[0010] The incident end of the optical element corresponds to the optical window, and is used to convert the incident light into parallel light perpendicular to the Z-axis;

[0011] The reflecting surface of the galvanometer corresponds to the output end of the optical element, and is used to change the angle of the parallel light;

[0012] The driving end of the driving part is connected to the galvanometer, its signal input end is electrically connected to the numerical control unit, and its signal output end is connected to the input end of the detector, and is used to drive the galvanometer to rotate according to the driving signal of the numerical control unit, so that its reflecting surface rotates around the Z-axis, and when it rotates to a uniform state with the same speed and opposite direction as the turntable, a trigger signal is sent to the detector;

[0013] The detection surface of the detector corresponds to the reflecting surface of the galvanometer, and its output end is electrically connected to the numerical control unit, and is used to perform target detection according to the trigger signal.

[0014] Further, the numerical control unit is an FPGA control board.

[0015] Further, the driving part is a driving motor.

[0016] Further, the optical element is a front telescopic lens.

[0017] Further, the detector is an infrared focal plane detector.

[0018] A galvanometer control method for a tracking and searching system, adopting the above-mentioned galvanometer control device for a tracking and searching system, is characterized in that it includes the following steps:

[0019] Step 1: The optical element collimates the incident light entering the optical window on the cavity into parallel light, and the galvanometer reflects the parallel light to the detection surface of the detector;

[0020] Step 2: Start the turntable to rotate uniformly through the numerical control unit, the angle encoder measures the azimuth rotation angle A of the turntable in real time, and sends the azimuth rotation angle A to the numerical control unit;

[0021] Step 3: When the turntable rotates to the preset turntable zero position angle A0, the numerical control unit starts to record the increment ΔA of the turntable azimuth rotation angle A, sends a drive signal to the drive, and records the frame number n as 1 at the same time;

[0022] Step 4: The numerical control unit compares the increment ΔA with the preset equally spaced angle Δa;

[0023] When ΔA - Δa < 0°, step 5 is executed;

[0024] When ΔA - Δa ≥ 0°, step 6 is executed;

[0025] Wherein, Δa = 360° / N, and N is the preset maximum frame number;

[0026] Step 5: Determine whether detection data has been obtained once under the current frame number n; if so, return to step 4; if not, obtain detection data according to the following steps A to C;

[0027] A. The drive receives the drive signal, drives the galvanometer to rotate around the z-axis starting from the preset galvanometer zero position angle. When the galvanometer rotates to a uniform speed state, the drive sends a trigger signal to the detector; the speed of the uniform speed state of the galvanometer is equal to and in the opposite direction of the rotation speed of the turntable;

[0028] B. The detector receives the trigger signal, performs an exposure on the light beam reflected by the galvanometer, and then sends the obtained detection data to the numerical control unit;

[0029] C. When the galvanometer rotates to the preset angle, the drive drives the galvanometer to return to the preset galvanometer zero position angle, and returns to step 4;

[0030] Step 6: Determine whether the current frame number n is greater than or equal to N. If not, execute step 7; if so, execute step 8;

[0031] Step 7: The numerical control unit re-records the increment ΔA of the turntable azimuth rotation angle A, sends a drive signal to the drive, increments the frame number by 1 at the same time, and returns to step 4;

[0032] Step 8: The numerical control unit splices the N groups of detection data based on the order of the N frame numbers to obtain panoramic target picture data covering a 360° azimuth angle.

[0033] Further, in step 2, the rotation speed of the turntable is 1.6 seconds / rotation;

[0034] In step 4, the preset equally spaced angle Δa is 2.8125°.

[0035] Advantages of the present invention:

[0036] 1. The galvanometer control device and method for a tracking and searching system provided by the present invention control the timing of exposure for each frame of image by reasonably designing the swing scanning time of the galvanometer, ensuring accurate image shift compensation during the periodic scanning of the azimuth turntable, and making the target picture data clear and without trailing.

[0037] 2. For the galvanometer control device and method for a tracking and searching system provided by the present invention, the first picture data generated each time the turntable rotates one circle is exposed at the same azimuth angle, ensuring that the subsequent generated picture data all have fixed exposure positions and time intervals. Eventually, the optical axis under staring compensation has consistency. After splicing the multiple picture data obtained by rotating one circle, a panoramic target picture data with a stable 360° azimuth angle can be obtained.

[0038] 3. The galvanometer control device for a tracking and searching system provided by the present invention uses an FPGA control board as the numerical control unit, and adopts a reverse scanning trigger and exposure implementation strategy with the FPGA as the control core, using the parallel processing of the FPGA to reduce the overall calculation and processing delay. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic structural diagram of an embodiment of the galvanometer control device for a tracking and searching system of the present invention;

[0040] Figure 2 is a schematic diagram of the timing relationship between various signals in the embodiment of the present invention;

[0041] Figure 3 is a flowchart of an embodiment of the galvanometer control method for a tracking and searching system of the invention.

[0042] REFERENCE NUMERALS IN THE DRAWINGS:

[0043] 1 - optical window, 2 - cavity, 3 - turntable, 4 - angle encoder, 5 - optical element, 6 - galvanometer, 7 - driving member, 8 - detector, 9 - numerical control unit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0045] A galvanometer control device for a tracking and searching system provided by an embodiment of the present invention, as Figure 1As shown in the figure, it includes a cavity 2 with a light window 1 provided on its side wall, a two-axis turntable 3 and an angle encoder 4 provided outside the cavity 2, and an optical element 5, a galvanometer 6, a driving member 7, a detector 8 and a numerical control unit 9 provided inside the cavity 2; the optical element 8 is a front telescopic lens, the driving member 7 is a driving motor, and the detector 8 is an infrared focal plane detector.

[0046] For the convenience of description, in this embodiment, it is defined that the straight line where the rotation axis of the turntable 3 is located is the Z axis.

[0047] The rotating end of the turntable 3 is connected to the cavity 2, and its signal input end is electrically connected to the numerical control unit 9, and is used to drive the cavity 2 to rotate around the Z axis according to the instruction of the numerical control unit 9; the angle encoder 4 is arranged on the azimuth rotation axis of the turntable 3 and is electrically connected to the numerical control unit 9, and is used to measure the azimuth rotation angle of the turntable 3 and send it to the numerical control unit 9; the incident end of the optical element 5 corresponds to the light window 1 and is used to convert the incident light into parallel light perpendicular to the Z axis; the reflecting surface of the galvanometer 6 corresponds to the output end of the optical element 5 and is used to change the angle of the parallel light to compensate for image shift, so that the line-of-sight angle within a specific time is relatively in a static state; the driving end of the driving member 7 is connected to the galvanometer 6, its signal input end is electrically connected to the numerical control unit 9, and its signal output end is connected to the input end of the detector 8, and is used to drive the galvanometer 6 to reciprocate within a limited angle according to the driving signal of the numerical control unit 9, so that its reflecting surface rotates around the Z axis, and sends a trigger signal to the detector 8 when it rotates to a uniform speed state, and needs to return to the starting angle after each rotation to wait for the next rotation; the detection surface of the detector 8 corresponds to the reflecting surface of the galvanometer 6, and its output end is electrically connected to the numerical control unit 9, and is used to perform target detection according to the trigger signal.

[0048] In this embodiment, the numerical control unit 9 adopts an FPGA control board; FPGA is a semiconductor device with a large number of basic logic units inside. It is developed and designed through a hardware description language and can be combined into various complex digital circuits and systems according to the user's design and configuration. It can be used to implement the staring compensation strategy of the infrared tracking and search system. Since FPGA can process multiple tasks and data streams simultaneously, realizing efficient parallel computing, greatly improving the data processing speed and the real-time performance of the system, it has obvious advantages when implementing the staring compensation strategy, and can synchronously calculate the azimuth turntable data transceiver and processing, the calculation of the swing scanning moment, etc., reducing the calculation delay of each link.

[0049] Since the galvanometer 6 can only perform one-dimensional rotational motion within a limited angle, in order to achieve the same speed and reverse motion as the turntable 3, it must perform reverse motion of acceleration, uniform speed, and deceleration within a fixed range. When it reaches the same speed and reverse moment as the turntable 3, an integral synchronization signal (trigger signal) is sent to the infrared focal plane detector to expose and output pictures. See the Figure 2 figure for the timing relationship.

[0050] Using the above control device for galvanometer control, as Figure 3 shown, specifically including the following steps:

[0051] Step 1: The optical element 5 collimates the incident light entering the optical window 1 on the cavity 2 into parallel light, and the galvanometer 6 reflects the parallel light to the detection surface of the detector 8;

[0052] Step 2: Start the turntable 3 to rotate at a constant speed of V = 1.6 seconds / rotation through the numerical control unit 9. The angle encoder 4 measures the azimuth rotation angle A of the turntable 3 in real time and sends the azimuth rotation angle A to the numerical control unit 9;

[0053] The angle encoder 4 communicates with the numerical control unit 9 through the synchronous serial port method. The numerical control unit 9 receives the azimuth angle source code value with a frequency exceeding 1 kHz generated by the angle encoder 4 in real time, and then through internal decoding calculation and filtering processing, converts the received azimuth angle source code value into the azimuth rotation angle A;

[0054] Step 3: When the turntable 3 rotates to the preset turntable zero position angle A0, the numerical control unit 9 starts to record the increment ΔA of the turntable azimuth rotation angle A, sends a drive signal to the drive motor, and records the frame number n as 1 at the same time;

[0055] The numerical control unit 9 sends the drive signal to the drive motor through the differential level signal.

[0056] Step 4: The numerical control unit 9 compares the increment ΔA with the preset equal interval angle Δa;

[0057] When ΔA - Δa < 0°, execute Step 5;

[0058] When ΔA - Δa ≥ 0°, execute Step 6;

[0059] Among them, Δa = 360° / N = 2.8125°, N is the preset maximum frame number and N = V / T = 1.6 / 0.0125 = 128;

[0060] Step 5: Determine whether detection data has been obtained once under the current frame number n; if so, return to Step 4; if not, obtain the detection data according to the following Steps A to C;

[0061] A. The driving part 7 receives the driving signal and drives the galvanometer 6 to rotate around the z-axis starting from the preset galvanometer zero position angle. When the galvanometer 6 rotates to the uniform speed state, the driving part 7 sends an integration synchronization signal (trigger signal) to the detector 8; the rotation state of the galvanometer 6 is successively the acceleration state, the uniform speed state, and the deceleration state, and its uniform speed state speed is equal to and opposite to the rotation speed of the turntable;

[0062] B. The 8 detectors receive the trigger signal, perform a single exposure on the light beam reflected by the galvanometer 6, generate a CameraLink image (a digital signal format for transmitting images), i.e., the detection data, and send it to the numerical control unit 9; the time interval T for each acquisition of the detection data is 0.0125 seconds, that is, the frequency of each frame of the image is 80 Hz.

[0063] C. When the galvanometer 6 rotates to the preset angle, the driving member 7 drives the galvanometer 6 to return to the preset zero position angle of the galvanometer, and returns to step 4;

[0064] In this embodiment, the time for the galvanometer 6 to move one scanning cycle should be less than 0.0125 seconds.

[0065] Step 6. Determine whether the current frame number n is greater than or equal to N. If not, execute step 7; if so, execute step 8;

[0066] Step 7. The numerical control unit 9 re - records the increment ΔA of the rotation angle A of the turntable azimuth, sends a driving signal to the driving member 7, adds 1 to the frame number at the same time, and returns to step 4;

[0067] Step 8. The numerical control unit 9 splices the N groups of detection data in the order of N frame numbers to obtain panoramic target picture data covering a 360° azimuth angle.

[0068] As described above, the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A galvanometer control device for a tracking and searching system, characterized in that: It comprises a cavity (2) with a light window (1) on the side wall, a turntable (3) and an angle encoder (4) arranged outside the cavity (2), and an optical element (5), a galvanometer (6), a driving member (7), a detector (8) and a numerical control unit (9) arranged inside the cavity (2); Definition: The straight line where the rotation axis of the turntable (3) is located is the Z axis; The rotating end of the turntable (3) is connected to the cavity (2), and the signal input end thereof is electrically connected to the numerical control unit (9), so as to drive the cavity (2) to rotate at a constant speed around the Z axis according to the instruction of the numerical control unit (9); The angle encoder (4) is arranged on the rotating shaft of the turntable (3) and is electrically connected to the numerical control unit (9) for measuring the azimuth rotation angle of the turntable (3) and sending the measured value to the numerical control unit (9); The incident end of the optical element (5) corresponds to the light window (1) and is used to convert the incident light into parallel light perpendicular to the Z axis; The reflective surface of the galvanometer (6) corresponds to the emission end of the optical element (5) and is used to change the angle of the parallel light; The driving end of the driving member (7) is connected to the galvanometer (6), the signal input end thereof is electrically connected to the numerical control unit (9), and the signal output end thereof is connected to the input end of the detector (8), and is used for driving the galvanometer (6) to rotate according to the driving signal of the numerical control unit (9), so that its reflection surface rotates around the Z axis, and sending a trigger signal to the detector (8) when it rotates to a uniform speed state equal to the rotation speed of the turntable and in the opposite direction; The detection surface of the detector (8) corresponds to the reflection surface of the galvanometer (6), and its output end is electrically connected to the numerical control unit (9) for performing target detection according to the trigger signal.

2. The galvanometer control device for a tracking and searching system according to claim 1, characterized in that: The numerical control unit (9) is an FPGA control board.

3. The galvanometer control device for a tracking and searching system according to claim 2, characterized in that: The driving member (7) is a driving motor.

4. The galvanometer control device for a tracking and searching system according to claim 1, 2 or 3, characterized in that: The optical element (8) is a front telephoto lens.

5. The galvanometer control device for a tracking and searching system according to claim 4, characterized in that: The detector (8) is an infrared focal plane detector.

6. A galvanometer control method for a tracking and searching system, using the galvanometer control device for a tracking and searching system according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1, the optical element (5) collimates the incident light entering the light window (1) on the cavity (2) into parallel light, and the galvanometer (6) reflects the parallel light to the detection surface of the detector (8); Step 2: The turntable (3) is started to rotate at a constant speed by the numerical control unit (9); the angle encoder (4) measures the azimuth rotation angle A of the turntable (3) in real time, and sends the azimuth rotation angle A to the numerical control unit (9); Step 3, when the turntable (3) rotates to a preset turntable zero angle A0, the numerical control unit (9) starts to record the increment ΔA of the turntable azimuth rotation angle A, and sends a driving signal to the driving member (7), and simultaneously records the frame number n as 1; Step 4, the numerical control unit (9) compares the increment ΔA with the preset equally spaced angle Δa; When ΔA-Δa<0°, execute step 5; When ΔA-Δa≥0°, execute step 6; Wherein, Δa=360° / N, N is the preset maximum frame number; Step 5, determine whether detection data has been acquired once under the current frame number n; if so, return to step 4; if not, obtain detection data according to the following steps A to C; A. The driving member (7) receives a driving signal and drives the galvanometer (6) to rotate around the z-axis from a preset galvanometer zero angle. When the galvanometer (6) rotates to a uniform speed state, the driving member (7) sends a trigger signal to the detector (8); the uniform speed of the galvanometer (6) is equal to the rotation speed of the turntable and in the opposite direction; B. The detector (8) receives the trigger signal and exposes the light beam reflected by the galvanometer (6) once, and then sends the acquired detection data to the numerical control unit (9); C. When the galvanometer (6) rotates to a preset angle, the driving member (7) drives the galvanometer (6) to return to the preset galvanometer zero angle, and the process returns to step 4; Step 6: Determine whether the current frame number n is greater than or equal to N. If not, go to step 7; if so, go to step 8; Step 7, the numerical control unit (9) re-records the increment ΔA of the turntable azimuth rotation angle A, sends a driving signal to the driving element (7), increases the frame number by 1, and returns to step 4; Step 8: The numerical control unit (9) splices the N groups of detection data based on the order of the N frame numbers to obtain panoramic target image data covering a 360° azimuth angle.

7. The galvanometer control method for a tracking and searching system according to claim 6, characterized in that: In step 2, the rotation speed of the turntable (3) is 1.6 seconds per revolution; In step 4, the preset equally spaced angle Δa is 2.8125°.

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