System and method for stabilizing and precisely tracking rotary table based on fast reflecting mirror

Abstract

The invention discloses a system and method for stabilizing and precisely tracking a rotary table based on a fast reflecting mirror, and belongs to the technical field of photoelectric precise control, the system comprises a main control computer, the rotary table, a rotary table frame, a servo main control board, the fast reflecting mirror, a gyroscope, an image processing board and a precise tracking image sensor, all the modules work cooperatively, integration is carried out according to the speed residual value of the rotary table, and precise tracking is carried out. The position quantity obtained through integration serves as an input instruction angle of the fast steering mirror, secondary stability of the rotary table is achieved, and accurate positioning and tracking of a target can be achieved; the problems that an existing rotary table system is insufficient in stability and tracking precision, the function of the fast steering mirror is single, and the stroke is limited are solved, the stability and tracking performance of the rotary table system at different angles under the dynamic condition is improved, and the requirements for stability and tracking precision within the 10urad magnitude are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic precision control, and particularly relates to a system and method for realizing the stability and precise tracking of a turntable based on a fast steering mirror. Background Art

[0002] In many optical application fields, as a key component for carrying optical equipment, the stability and tracking performance of a turntable are crucial. The existing turntable system solutions are limited by the high inertia and low stiffness characteristics of the mechanical structure, and their bandwidths are generally lower than 30 Hz, and the stable tracking accuracy is only of the order of 200 urad. In order to improve the performance of the turntable system, the traditional solution realizes single-function compensation by introducing a fast steering mirror (FSM). This solution either focuses on precise tracking or on vibration suppression, and it is difficult to meet the dual requirements of wide-range tracking and high-frequency disturbance compensation. In addition, the problem of integral saturation caused by the gyro drift of the turntable easily leads to the fast steering mirror exceeding its stroke, resulting in the improved turntable being difficult to achieve all-round stability and tracking, which restricts the reliability of the turntable system.

[0003] Application No. 202110075781.0 discloses a method for measuring the stability accuracy of a coarse-fine combined two-stage stable optoelectronic system. It introduces a method for measuring an optoelectronic system based on gyro and fast steering mirror (FSM) signals, does not realize the two-stage stable function, and the follow-up function according to the position information of the fast steering mirror.

[0004] Application No. 2017103218878.0 discloses a coarse-fine tracking experimental turntable equipped with a fast steering mirror. It introduces a method of first locking the target in the coarse tracking field of view by the turntable and then using the fast steering mirror for fine adjustment to achieve precise tracking. It does not realize the follow-up control between the fast steering mirror and the turntable. At the same time, due to the lack of stable compensation, the turntable can only be used in an indoor environment and is not suitable for installation on a dynamic base. Summary of the Invention

[0005] The purpose of the present invention is to provide a system and method for realizing the stability and precise tracking of a turntable based on a fast steering mirror, so as to solve the problems of insufficient stability and tracking accuracy of the existing turntable system, as well as the single function and limited stroke of the fast steering mirror, and improve the stability and tracking performance of the turntable system at different angles under dynamic conditions to meet the requirements of stability and tracking accuracy within the order of 10 urad.

[0006] The technical solution of the present invention is as follows. A system for realizing the stability and precise tracking of a turntable based on a fast steering mirror includes: a main control computer, a turntable, a turntable frame, a servo main control board, a fast steering mirror, a gyroscope, an image processing board, and a precise tracking image sensor. Each module works collaboratively in the following way: The main control computer is used to generate turntable motion commands and coordinate each subsystem; the turntable frame is used to carry each component and can rotate in two axes of azimuth and elevation; the servo main control board includes a speed loop, a current loop, a position servo loop, and a turntable drive module, and can control the two-axis rotation of the turntable frame. The servo main control board receives the miss distance of the image processing board, gyroscope data, and the feedback angle information of the fast steering mirror; the fast steering mirror is integrated into the turntable optical path to perform angle compensation and precise tracking; the gyroscope is used to measure the angular velocity of the turntable in real time and provide a speed signal; the image processing board is used to calculate the miss distance information of the target deviating from the center of the field of view for facilitating precise tracking control; the precise tracking image sensor can obtain the target miss distance for precise tracking control.

[0007] Further, an integration module is provided inside the speed loop.

[0008] A method for realizing the stability of the turntable based on a fast steering mirror integrates according to the speed residual value of the turntable, and takes the integrated position quantity as the input command angle of the fast steering mirror to realize the secondary stability of the turntable.

[0009] Further, specifically, by obtaining the turntable speed information measured by the gyroscope in real time, comparing it with the set ideal speed to obtain the speed residual value, performing an integration operation on this residual value, converting the integration result into a control signal of the fast steering mirror, driving the fast steering mirror to adjust the angle, thereby compensating for the motion deviation of the turntable and improving the stability accuracy of the turntable.

[0010] A method for realizing precise tracking based on a fast steering mirror. The turntable transmits the miss distance calculated by the image processing board to the servo main control board. The servo main control board calculates according to the optical magnification of the turntable, focal length, and pixel size, converts it into the angle of the fast steering mirror to perform precise tracking on the tracking object. The precise tracking image sensor collects the target image in real time, the image processing board calculates the miss distance of the target relative to the center of the field of view, and transmits this miss distance to the servo main control board. According to parameters such as the optical magnification, focal length, and pixel size of the turntable, through a specific calculation formula, the miss distance is converted into the angle value that the fast steering mirror needs to adjust, and then the fast steering mirror is controlled to precisely adjust the angle to realize the precise positioning and tracking of the target.

[0011] Further, the fast steering mirror real-time feeds back its own angle information to the position servo loop of the servo main control board. The position servo loop calculates the speed quantity through a model according to the received angle of the fast steering mirror. This speed quantity is combined with the set speed signal of the turntable to jointly control the speed loop of the turntable, and then through the current loop and the turntable drive module, control the motion of the turntable, so that the fast steering mirror is always near the zero position, realizing the stability and tracking accuracy compensation of the turntable under dynamic conditions.

[0012] The beneficial effects of the present invention are as follows: By introducing a fast steering mirror and placing it in the turntable optical path, the present invention simultaneously realizes the fine tracking and secondary stabilization functions, significantly improves the stability and tracking accuracy of the turntable, can meet the high-precision stable tracking requirements within 10 urad, has a substantial improvement in performance compared with traditional turntables, and the added turntable follow-up loop effectively solves the problem of limited stroke of the fast steering mirror, enabling the turntable to achieve all-round stability and tracking without being restricted by the stroke of the fast steering mirror, improving the reliability and adaptability of the system, and can be widely applied to various complex environments and scenarios with high-precision requirements. Only one fast steering mirror can achieve tracking compensation and stability compensation, making full use of the performance of the fast steering mirror and avoiding the use of two fast steering mirrors, thus reducing costs. Description of the Drawings

[0013] Figure 1 It is a block diagram of the system composition of the present invention.

[0014] Figure 2 It is a principle block diagram of the stable control method of the present invention.

[0015] Figure 3 It is a principle block diagram of the fine tracking control method of the present invention.

[0016] Figure 4 It is a principle block diagram of the method for solving the stroke of the fast steering mirror of the present invention.

[0017] Figure 5 It is a connection block diagram of the fast steering mirror and the turntable of the present invention. Detailed Embodiments

[0018] It should be noted that in the description of the present invention, the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is 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.

[0019] In the present invention, unless otherwise clearly defined and limited, the terms "set", "install", "connect", "couple", etc. should be understood in a broad sense. For example, "fix" can be a fixed connection, a detachable connection, or integrated; the connection can be a mechanical connection or an electrical connection; the coupling can be a direct coupling or an indirect coupling through an intermediate medium, and can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] A system for achieving turntable stability and precise tracking based on a fast steering mirror, comprising: a main control computer, a turntable frame, a servo main control board, a fast steering mirror, a gyroscope, an image processing board, and a precise tracking image sensor. Each module works collaboratively in the following way: The main control computer is used to generate turntable motion instructions and coordinate each subsystem; The turntable frame is used to carry each component and can rotate in two axes of azimuth and elevation; The servo main control board includes a speed loop, a current loop, a position servo loop, and a turntable drive module. The servo main control board receives the feedback angle information of the fast steering mirror; The fast steering mirror is integrated into the turntable optical path to perform stable angle compensation and precise tracking; The gyroscope is used to measure the angular velocity of the turntable in real time and provide a speed signal; The image processing board is used to calculate the miss distance information of the target deviating from the center of the field of view, facilitating precise tracking control; The precise tracking image sensor can acquire the target and transmit the image signal to the image processing board.

[0021] A method for achieving turntable stability based on a fast steering mirror. The servo main control board integrates according to the speed residual value of the turntable, and takes the integrated position quantity as the input command angle of the fast steering mirror to achieve secondary stability of the turntable.

[0022] Specifically, by obtaining the speed information of the turntable measured by the gyroscope in real time, calculating the speed residual value by comparing it with the set ideal speed, performing an integration operation on this residual value, converting the integration result into a control signal for the fast steering mirror, driving the fast steering mirror to adjust the angle, thereby compensating for the motion deviation of the turntable and improving the stability accuracy of the turntable.

[0023] A method for solving the stroke problem of the fast steering mirror. Due to the drift characteristics of the gyroscope, long-term integration will cause the integrated quantity to exceed the maximum stroke of the fast steering mirror. For this reason, the servo main control board needs to receive the real-time angles of the two axes of the fast steering mirror. The servo main control board adds a position servo loop to make the turntable perform position servo according to the fast steering mirror angle. The fast steering mirror feeds back its own angle information to the position servo loop of the servo main control board in real time. The position servo loop calculates the speed quantity through a PI model according to the received fast steering mirror angle. This speed quantity is combined with the turntable set speed signal to jointly control the speed loop of the turntable, and then through the current loop and the turntable drive module, the motion of the turntable is controlled. This makes the fast steering mirror always stay near the zero position, ensuring the optimal accuracy and bandwidth performance of the fast steering mirror, and realizing the stability and tracking accuracy compensation of the turntable under dynamic conditions.

[0024] A precise tracking method based on a fast steering mirror. The turntable transmits the off-target amount calculated by the image processing board to the servo main control board. The servo main control board calculates based on the optical magnification, focal length, and pixel size of the turntable, converts it to the angle of the fast steering mirror, and performs precise tracking on the tracking object. The target image is collected in real time through the precise tracking image sensor. The image processing board calculates the off-target amount of the target relative to the center of the field of view and transmits this off-target amount to the servo main control board. According to parameters such as the optical magnification, focal length, and pixel size of the turntable, through a specific calculation formula, the off-target amount is converted into the angle value that the fast steering mirror needs to adjust, and then the fast steering mirror is controlled to precisely adjust the angle, achieving precise positioning and tracking of the target. Embodiment

[0025] First, during the operation of the turntable, the gyro continuously measures the real-time speed ω(t) of the turntable, and the main control computer transmits the set speed ω 0 (t) to the turntable. The gyro uses a gyro with high-precision low-temperature drift characteristics, and its measurement resolution can reach 0.002° / s.

[0026] The turntable compares the received gyro speed signal with the pre-set ideal speed, and calculates the speed residual value △ω(t)=ω(t)-ω 0 (t). When the turntable receives the set ideal speed of ω(t)=0° / s and the speed measured by the gyro is ω 0 (t)=0.05° / s, then the speed residual value is △ω(t)= -0.05° / s.

[0027] Integral operation is performed on the speed residual value to calculate the angle that needs to be compensated , K i is the integral gain. The integral gain K i is taken as 1, and an integrator with an integral time constant of 0.001s is used. After 1s, the integral amount is -0.05° / s×1s = -0.05°.

[0028] The resolution of the fast steering mirror is θ LSB , and the integral amount is converted into the control angle θ code1 of the fast steering mirror, , the resolution of the fast steering mirror is θ LSB =0.5urad, and the angle code value that the fast steering mirror needs to adjust is code value. The calculated angle is sent to the fast steering mirror to drive the fast steering mirror to adjust the angle. The fast steering mirror precisely adjusts its own angle according to the control signal, compensates for the motion deviation of the turntable system, and realizes secondary stabilization.

[0029] Specific implementation of precise tracking control The fine-tracking image sensor collects the target image in real time, using a CMOS image sensor with a resolution of 1920×1080 and a frame rate of 100fps.

[0030] Calculate the miss distance of the target relative to the center of the field of view. Through the image recognition algorithm, determine the position of the target in the image, compare it with the position of the center of the field of view, and obtain the miss distance of the target.

[0031] When the number of pixels d of the miss distance of the target deviates from the center of the field of view in the horizontal direction x is 50, the turntable control system converts the miss distance into the angle value that the fast steering mirror needs to adjust according to the optical magnification S of the turntable being 10 times, the focal length f = 500mm, and the pixel size M = 2.5μm. The calculation formula is: , substituting the values and calculating to obtain the angle value of 2.5mrad.

[0032] The control system converts the calculated angle value into the code value of the fast steering mirror , controls the fast steering mirror to accurately adjust the angle, and realizes the fine tracking of the target.

[0033] Specific implementation of solving the stroke problem of the fast steering mirror The fast steering mirror feeds back its biaxial angle information to the turntable in real time. The fast steering mirror is driven by a voice coil motor, with a maximum stroke of ±5mrad and an angle measurement accuracy of up to 0.5urad, and can accurately measure and feedback its own angle.

[0034] The turntable calculates the speed quantity that the position servo loop needs to output according to the received angle of the fast steering mirror. , combines the speed quantity V generated by the position servo loop com with the original input quantity of the turntable speed loop to jointly control the turntable, drive the turntable to move, so that the fast steering mirror is always near the zero position, ensure the optimal accuracy and bandwidth performance of the fast steering mirror, and realize the stability and tracking accuracy compensation of the turntable under dynamic conditions.

[0035] 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 person skilled in the art within the technical scope disclosed by the present invention, any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention shall be covered by the protection scope of the present invention. At the same time, the content not described in detail in this specification belongs to the prior art well known to those skilled in the art.

[0036] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent in such process, method, article or device.

Claims

1. A system for realizing turntable stabilization and precise tracking based on a fast-reflection mirror, characterized in that: include: The main control computer, turntable, turntable frame, servo main control board, fast reflex mirror, gyroscope, image processing board and precision tracking image sensor, each module works together in the following ways: the main control computer is used to generate turntable motion instructions and coordinate various subsystems; the turntable frame is used to carry various components and can rotate in two axes of azimuth and pitch; the servo main control board includes a speed loop, a current loop, a position follower loop and a turntable drive module, which can control the two-axis rotation of the turntable frame, and the servo main control board receives the miss distance, gyroscope data and fast reflex mirror feedback angle information from the image processing board; the fast reflex mirror is integrated in the turntable optical path to perform angle compensation and precision tracking; The gyroscope is used to measure the angular velocity of the turntable in real time and provide a velocity signal; The image processing board is used to calculate the target's miss distance information when it deviates from the center of the field of view, so as to facilitate precise tracking control; The precision tracking image sensor can obtain the target miss distance for precision tracking control.

2. The system for realizing turntable stabilization and precise tracking based on a fast-reflection mirror according to claim 1, characterized in that: An integral module is provided in the speed loop.

3. A method for realizing turntable stabilization based on a fast-reflection mirror, characterized in that: According to claim 1, the velocity residual value of the turntable is integrated, and the position value obtained by the integration is used as the input instruction angle of the fast reflection mirror to achieve secondary stabilization of the turntable.

4. The method for realizing turntable stabilization based on a fast reflection mirror according to claim 3, characterized in that: Specifically, the turntable speed information measured by the gyroscope is obtained in real time, and the speed residual value is compared with the set ideal speed. The residual value is integrated and the integration result is converted into a control signal of the fast-reflection mirror, which drives the fast-reflection mirror to adjust the angle, thereby compensating for the motion deviation of the turntable and improving the stability and accuracy of the turntable.

5. The method for realizing turntable stabilization based on a fast reflection mirror according to claim 4, characterized in that: The fast-reflex mirror feeds back its own angle information to the position follower loop of the servo main control board in real time. The position follower loop calculates the speed through the model based on the received fast-reflex mirror angle. The speed is combined with the turntable set speed signal to jointly control the turntable speed loop, which then passes through the current loop and the turntable drive module to control the movement of the turntable, so that the fast-reflex mirror is always near the zero position, thereby achieving dynamic stability and tracking accuracy compensation of the turntable.

6. A method for realizing precise tracking based on a fast-reflection mirror, characterized in that: According to claim 1, the turntable transmits the miss amount calculated by the image processing board to the servo main control board, the servo main control board calculates according to the optical magnification, focal length and pixel size of the turntable, and converts it to the angle of the fast reflex mirror to accurately track the tracking object, and collects the target image in real time through the fine tracking image sensor, the image processing board calculates the miss amount of the target relative to the center of the field of view, and transmits the miss amount to the servo main control board, according to the optical magnification, focal length and pixel size of the turntable, through a specific calculation formula, the miss amount is converted into the angle value that the fast reflex mirror needs to adjust, and then the fast reflex mirror is controlled to accurately adjust the angle, so as to achieve accurate positioning and tracking of the target.

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