A high-precision stable tracking method

Abstract

This invention provides a high-precision, stable tracking method, relating to the field of photoelectric control technology, comprising: S1: When the DIRCM acquires the initial position of the target, the position loop is controlled by a cosine trajectory planning controller to control the aiming line to reach the designated position; S2: The automatic video tracker uses full-pixel detection to output the target miss distance. After the target miss distance is compensated by a delay compensator, it is input into the coarse tracking controller to obtain the velocity loop control quantity. The velocity loop control quantity is input into the velocity loop to keep the target within the field of view; S3: The automatic video tracker uses 30% pixel detection to output the target miss distance. After the target miss distance is compensated by a delay compensator, it is input into the fine tracking controller to obtain the velocity loop control quantity. The velocity loop control quantity is input into the velocity loop to keep the target at the center of the field of view. This method includes a delay compensation strategy and a variable detector integration time control strategy, which respectively solve the problems of miss distance output delay and detector integration time.

Description

Technical Field

[0001] This invention relates to the field of photoelectric control technology, and in particular provides a high-precision, stable tracking method. Background Technology

[0002] Directed Infrared Countermeasures (DIRCM) systems protect aircraft from infrared-guided missiles. A DIRCM's stabilization platform typically employs a frame-type reflector configuration with a small external envelope, providing pointing capability along two axes. The DIRCM also includes an infrared camera and a jamming laser. Once a target is detected, the reflector controls the optical axis direction to continuously track the target, while the laser jamming is activated until the infrared-guided missile deviates from the platform. The infrared camera has a certain integration time and output frame rate; during this process, the stabilization platform's line of sight is susceptible to aircraft motion. The largest angular motion occurs during aircraft roll, pitch, or yaw, typically reaching up to 400 degrees per second. Because the DIRCM head is mounted externally to the aircraft, the line of sight can be severely affected during the infrared camera's integration time. Another major factor contributing to angular motion is aircraft vibration. Therefore, without compensation, the aiming point is susceptible to motion during the detector's integration time. When using a directed infrared countermeasures system to illuminate a target, the problem becomes how to counteract the aircraft's motion.

[0003] The stabilization platform of a directional infrared countermeasures system typically employs a semi-stripper stabilization method. An inertial measurement unit (IMU) is mounted on the platform's base. The measured inertial angular velocity of the carrier and the angular velocity of the frame reconstruct the line-of-sight (LOS) motion characteristics, and the calculated LOS inertial angular velocity is used as feedback for LOS stabilization control, thus counteracting the carrier's angular motion. The carrier's linear motion and the target's motion are primarily counteracted by an automatic video tracking loop. The automatic video tracker detects the deviation of the target image relative to the LOS within the field of view—the target miss distance—which serves as the error control signal for the inertial stabilization platform. After correction, the miss distance is used to control the gimbal movement to align the LOS with the target, achieving real-time target tracking. However, the output delay of the miss distance and the detector integration time in the tracking loop significantly impact the control bandwidth and phase margin of the tracking loop, having the most severe effect on the tracking loop itself. Summary of the Invention

[0004] The purpose of this application is to provide a high-precision and stable tracking method to solve the problems of off-target output delay and detector integration time.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A high-precision, stable tracking method, the method comprising:

[0007] S1: When DIRCM obtains the initial position of the target, the position loop is controlled by a cosine trajectory planning controller to control the aiming line to reach the specified position;

[0008] S2: After the aiming line reaches the designated position, the automatic video tracker uses full-pixel detection to output the target miss amount. After the target miss amount is compensated by the delay compensator, it is input into the coarse tracking controller to obtain the velocity loop control amount. The velocity loop control amount is input into the velocity loop to keep the target within the field of view.

[0009] S3: After the automatic video tracker captures the target within the field of view, it uses 30% pixel detection to output the target miss amount. After the target miss amount is compensated by the delay compensator, it is input into the precision tracking controller to obtain the speed loop control quantity. The speed loop control quantity is input into the speed loop to keep the target at the center of the field of view.

[0010] The high-precision stable tracking method provided by this invention also has the feature that the angular frequency ω and amplitude A of the cosine trajectory planning controller are calculated from the arrival time T.

[0011]

[0012] Where θ0 is the initial position of the target.

[0013] The high-precision stable tracking method provided by this invention also has the following feature: after compensation by the delay compensator, t k Miss amount at time for:

[0014]

[0015] Where θ(t) k-1 ) represents t k-1 Delay measurement of time, T ω Let n represent the update period of ω, and n represent [t]. k ,t k+1 The number of updates within the period, ω(t) k-1 +nT ω ) represents t k-1 +nT ω The speed of time, T represents the estimated angle of θ(t). θ This represents the update period of θ.

[0016] The high-precision stable tracking method provided by this invention also has the following feature: the gain K1 of the coarse tracking controller is...

[0017] K1 = 2π 2 f1 2

[0018] Where f1 is the bandwidth of the coarse tracking controller, and f1 is 1Hz-6Hz.

[0019] The high-precision stable tracking method provided by this invention also has the following feature: the gain K2 of the coarse tracking controller is...

[0020] K2 = 2π 2 f2 2

[0021] Where f2 is the bandwidth of the coarse tracking controller, and f2 is 20Hz-30Hz.

[0022] Beneficial effects

[0023] The tracking method provided by this invention includes a delay compensation strategy and a variable detector integration time control strategy, which respectively solve the problems of miss output delay and detector integration time. For the miss output delay problem, the time difference between the infrared imaging moment and the miss output moment is calculated using a unified timing system, and then the miss deviation is estimated based on the current velocity for compensation. For the lag problem caused by detector integration, all pixels of the detector are used for integration during the target search phase, achieving coarse tracking control using a low frame rate and a large field of view. During the target tracking phase, a windowed integration method is used, achieving fine tracking using a relatively high frame rate and a small field of view. Finally, high control bandwidth and high-precision tracking of the target are achieved. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a block diagram of the principle of an existing automatic video tracking control loop;

[0026] Figure 2 This is a block diagram illustrating the tracking loop compensation principle in the method provided in the embodiments of the present invention;

[0027] Figure 3 This is a block diagram of the DIRCM tracking control system in the method provided in the embodiments of the present invention. Detailed Implementation

[0028] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be noted that these embodiments are not intended to limit the present application. Equivalent transformations or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are all within the protection scope of the present application.

[0029] In the description of the embodiments of this application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the creation of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the creation of this application.

[0030] Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0031] The terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0032] like Figure 1-3 As shown in the figure, this application provides a high-precision stable tracking method, the method comprising:

[0033] S1: When DIRCM obtains the initial position of the target, the position loop is controlled by a cosine trajectory planning controller to control the aiming line to reach the specified position;

[0034] S2: After the aiming line reaches the designated position, the automatic video tracker uses full-pixel detection to output the target miss amount. After the target miss amount is compensated by the delay compensator, it is input into the coarse tracking controller to obtain the velocity loop control amount. The velocity loop control amount is input into the velocity loop to keep the target within the field of view.

[0035] S3: After the automatic video tracker captures the target within the field of view, it uses 30% pixel detection to output the target miss amount. After the target miss amount is compensated by the delay compensator, it is input into the precision tracking controller to obtain the speed loop control quantity. The speed loop control quantity is input into the speed loop to keep the target at the center of the field of view.

[0036] In some embodiments, the angular frequency ω and amplitude A of the cosine trajectory planning controller are calculated from the arrival time T.

[0037]

[0038] Where θ0 is the initial position of the target.

[0039] In some embodiments, t after compensation by the delay compensator k Miss amount at time for:

[0040]

[0041] Where θ(t) k-1 ) represents t k-1 Delay measurement of time, T ω Let n represent the update period of ω, and n represent [t]. k ,t k+1 The number of updates within the period, ω(t) k-1 +nT ω ) represents t k-1 +nT ω The speed of time, T represents the estimated angle of θ(t). θ This represents the update period of θ.

[0042] In some embodiments, the gain K1 of the coarse tracking controller is

[0043] K1 = 2π 2 f1 2

[0044] Where f1 is the bandwidth of the coarse tracking controller, and f1 is 1Hz-6Hz.

[0045] In some embodiments, the gain K2 of the coarse tracking controller is

[0046] K2 = 2π 2 f2 2

[0047] Where f2 is the bandwidth of the coarse tracking controller, and f2 is 20Hz-30Hz.

[0048] like Figure 2 The diagram shown is a block diagram of the tracking loop compensation principle. P represents the tracking controller, V represents the stabilizing loop, ∫ represents the integrator, Q represents the delay compensator, and z... -1 θ represents the delay element. r (t) represents the actual target position at time t in the continuous domain, θ r (k) represents the actual target position at time k in the discrete domain, ω rω(t) represents the speed control quantity calculated by the tracking controller, ω(t) represents the target speed at time t in the continuous domain, ω(k) represents the target speed at time k in the discrete domain, θ(t) represents the detected target position at time t in the continuous domain, θ(k) represents the detected target position at time k in the discrete domain, and θ(k-1) represents the detected target position at time k-1 in the discrete domain.

[0049] like Figure 3 The diagram shows the block diagram of the DIRCM tracking control system. When L1 is turned on, the cosine trajectory planning of the position controller generates a speed command signal. When L2 and K1 are turned on at the same time, the coarse tracking controller of the position controller generates a speed command signal to perform video tracking at a relatively low frame rate. When L3 and K2 are turned on at the same time, the fine tracking controller of the position controller generates a speed command signal.

[0050] In some embodiments, the tracking method is as follows:

[0051] S1: When DIRCM acquires the initial position of the target, the position loop controller switches to L1. At this time, the video tracker is in the off state, and the speed command signal is a smooth cosine signal generated by the cosine trajectory planner, which guides the aiming line to the specified position.

[0052] After DIRCM obtains the initial position θ0 of the target, it uses cosine trajectory planning to plan the velocity input of the stabilization loop, ensuring that both the initial and final accelerations of the velocity command are zero. The planned velocity command expression is A(1-cosωt). This ensures that... The rotation angle of the frame within the period is θ0, that is... but In this context, the angular frequency ω of the cosine trajectory planning is determined by the frame's acceleration α, i.e.

[0053] S2: After the aiming line reaches the designated position, the position loop controller switches to L2, the automatic video tracker switches to K1, and outputs the target position using a relatively low frame rate of 60Hz.

[0054] S3: After the automatic video tracker captures the target, the position loop controller switches to L3, the automatic video tracker switches to K2, and outputs the target position using a relatively high frame rate of 300Hz to obtain high-gain tracking loop control.

[0055] When the position loop controller switches to L2 and L3, the miss delay compensation is in an effective state.

[0056] To reduce the impact of the output delay of the video tracker's miss distance, the current angle value and velocity integral are used for estimation, as detailed below:

[0057] Let θ(t) represent the estimated angle, which is only updated after the video tracker measures a new angle. k =kT θ k is an integer, T θ This represents the update period of θ. (Estimated value) In [t k ,t k+1 The value remains constant throughout the period, which can be represented as:

[0058]

[0059] Where θ(t) k-1 ) represents t k-1 Time delay measurement, Let ω(τ) represent the velocity integral over the entire sampling period Tθ, and let ω(τ) represent the velocity at time τ. The discrete expression is as follows:

[0060]

[0061] Among them, T ω Let n represent the update period of ω, and n represent [t]. k ,t k+1 The number of updates within a cycle.

[0062] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above description is merely a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A high-precision stable tracking method, characterized by, The method comprises: S1: when the DIRCM acquires the initial position of the target, a position loop adopts a cosine trajectory planning controller to control the line of sight to reach the specified position; S2: after the line of sight reaches the specified position, a full-pixel detection output target miss distance is output by the automatic video tracker, the target miss distance is compensated by a delay compensator, and then a speed loop control quantity is obtained by inputting a coarse tracking controller, and the speed loop control quantity is input into the speed loop to make the target in the field of view; S3: after the automatic video tracker captures the target in the field of view, a 30% pixel detection output target miss distance is output by the automatic video tracker, the target miss distance is compensated by the delay compensator, and then a speed loop control quantity is obtained by inputting a fine tracking controller, and the speed loop control quantity is input into the speed loop to make the target in the center of the field of view, The time-compensated delay The off-target amount at the time is: wherein represents the time delay measurement, represents the update period of represents the number of updates within a period, represents the velocity at the time, represents the estimated angle of represents the update period of 2. The high-precision stable tracking method according to claim 1, characterized by, The angular frequency ω and the amplitude A of the cosine trajectory planning controller are obtained by calculating the time T to reach the position, wherein, the initial position of the target.

3. The high-precision stable tracking method according to claim 1, characterized by, The gain K1 of the coarse tracking controller is Wherein, f1 is the bandwidth of the coarse tracking controller, and f1 is 1Hz-6Hz.

4. The high-precision stable tracking method according to claim 1, characterized by, The gain K2 of the fine tracking controller is Wherein, f2 is the bandwidth of the fine tracking controller, and f2 is 20Hz-30Hz.

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