A data weighted fusion tracking control method for an airborne optoelectronic tracking and aiming system

Abstract

The present invention belongs to the technical field of image tracking control, and discloses a data weighted fusion tracking control method for an airborne optoelectronic tracking and aiming system. The method includes measuring the delay of a tracking control loop and establishing a delay model, using the tracking deviation output by a tracker and the angular velocity signal of a fiber optic gyroscope as inputs, and reconstructing a high-bandwidth video tracking control loop. The control commands of the original video tracking control loop and the reconstructed loop are fused and output through data weighting, so as to achieve high-bandwidth control of the video tracking loop of the airborne optoelectronic tracking and aiming system. Compared with the traditional classical PID control, this method introduces more input information, effectively broadens the control bandwidth of the video tracking control loop, and improves the response speed of the optoelectronic tracking and aiming system to target movement.

Description

Technical Field

[0001] The present invention belongs to the technical field of image tracking control, and relates to a data weighted fusion tracking control method for an airborne optoelectronic tracking and aiming system. Background Art

[0002] The airborne optoelectronic tracking and aiming system is an important optoelectronic device installed on multiple platforms, which can complete tasks such as searching, identifying, aiming, tracking, laser ranging, and irradiating battlefield targets during day / night. As one of the important functions of the optoelectronic tracking and aiming system, the performance of the image tracking function largely determines the success or failure of the target tracking and striking tasks.

[0003] The video tracking function circuit of the optoelectronic tracking and aiming system consists of a video tracker, a servo control unit, a control handle, a display, and an operator to form a complete functional circuit. The operator selects and tracks the target by observing the display and operating the handle. The video tracker generates a tracking gate to capture and enclose the target, and the servo control unit then guides the optoelectronic tracking and aiming system to continuously and stably follow and point to the target according to the tracking deviation output by the video tracker.

[0004] The current typical video tracking control circuit of the airborne optoelectronic tracking and aiming system uses a 30Hz frame rate input. Since the delay caused by video sampling and tracking processing greatly limits the bandwidth of the tracking control circuit, the bandwidth of the tracking control circuit using traditional classical PID control can generally only reach 1 - 2Hz. This results in that the optoelectronic tracking and aiming system cannot achieve ideal effects in both the tracking response ability to fast maneuvering targets and the suppression ability to external disturbances, and cannot meet the requirements of the current airborne optoelectronic tracking and aiming system for fast and accurate tracking of maneuvering targets. Summary of the Invention

[0005] (1) Objects of the Invention

[0006] The object of the present invention is to provide a data weighted fusion tracking control method for an airborne optoelectronic tracking and aiming system, which can effectively improve the bandwidth of the video tracking control circuit and achieve a fast response to fast maneuvering targets.

[0007] (2) Technical Solutions

[0008] To solve the above technical problems, the present invention provides a data weighted fusion tracking control method for an airborne optoelectronic tracking and aiming system, including the following steps:

[0009] The first step is to measure the delay of the video tracking control circuit and generate a model.

[0010] Set the loop delay as τ 0 , and the loop delay model is G τ (s). Establish a delay model and obtain an approximate linearized model as shown below:

[0011]

[0012] The implementation process of the above first step is specifically as follows:

[0013] Step 1.1: Measure the delay of the video tracking control loop.

[0014] For the output signal of the angular position sensor of the optoelectronic tracking and aiming system, the real-time performance is relatively high. If it is assumed that the output value of the angular position sensor at time t 0 is X, and the angular position output by the video tracker at time t 1 is also X, then the tracking delay is calculated as follows:

[0015] τ 0 = t 1 - t 0

[0016] Step 1.2: Establish a delay model and linearize it.

[0017] According to the control system theory, the transfer function of the delay model is expressed as follows:

[0018]

[0019] In the formula, s represents the differential operator;

[0020] In order to be able to design using the linear control theory method, Taylor expansion is adopted here, and at the same time, the pade formula is used for truncation processing. Finally, the second-order approximate linearized model of the delay link, that is, formula (1), is obtained.

[0021] Second step, reconstruct and generate a high-bandwidth tracking control loop according to the tracking control loop delay model and the tracking control loop model.

[0022] The implementation process of the above second step is specifically as follows:

[0023] Step 2.1: Reconstruct the angular position signal without delay estimation.

[0024] To obtain the angular position of the optoelectronic tracking and aiming system under inertial control, it is obtained here by integrating the inertial angular velocity sensor (i.e., gyro). Assume that the angular position signal without delay estimation is

[0025]

[0026] In the formula, ω g is the angular velocity measured by the gyro;

[0027] Step 2.2: Reconstruct the angular position estimation signal after delay according to the measured delay model. This signal is obtained by superimposing the angular position signal in Step 1.1 with the delay model as follows:

[0028]

[0029] Step 2.3: Reconstruct the delay-free closed-loop control loop according to the tracking deviation output by the video tracker, the delay-free estimated angular position reconstructed in Step 2.1, and the delay-estimated angular position reconstructed in Step 2.2. If the tracking deviation output by the tracker is Δθ, the estimated tracking deviation output after reconstruction can be expressed as:

[0030]

[0031] Step 2.4: Reconstruct the loop tracking controller command generation. To obtain a high-bandwidth reconstructed tracking control loop command, a suitable controller needs to be applied as follows:

[0032]

[0033] In the above formula, K is the loop gain coefficient, and Q(s) is the loop low-pass filter.

[0034] Third step, generate the velocity feedforward control command according to the tracking deviation and the reconstructed delay loop. The velocity feedforward control command is as follows:

[0035]

[0036] Here, K v is the feedforward controller gain, and Q v (s) is the differential filter. Here, the target velocity angular position signal is obtained by adding the tracking deviation and the reconstructed delay loop, and the target velocity signal is obtained through the differential filter.

[0037] Fourth step, discretize the output of the reconstructed high-bandwidth tracking control loop and the feedforward control output, and generate the reconstructed command; here, the common bilinear transformation is used to obtain the discrete reconstructed tracking control loop. If the control period of the tracking control loop is T, the above transfer function is transformed from the s-domain to the z-domain for discretization to obtain the digital controller and as follows:

[0038]

[0039]

[0040] Fifth step, perform weighted fusion on the reconstructed high-bandwidth tracking control loop command, the feedforward control command, and the original forward tracking control loop command and output. If it is assumed that the tracking control command of the original tracking control loop is U0 , the control command generated by weighted fusion tracking is as follows:

[0041]

[0042] In the above formula, α is the weighting coefficient, which is dynamically adjusted according to the magnitude of the tracking deviation.

[0043] In this step, by performing weighted summation on the control command output by the original tracking control loop and the command output by the reconstructed tracking control loop, and outputting together with the feedforward control command, the gyro data and the tracking deviation input data are fused to form a new tracking control output.

[0044] (3) Beneficial effects

[0045] Currently, most tracking control systems mostly adopt the traditional PID control method, and obtain the final control parameters and control effects through a certain parameter tuning method. Since only the tracking deviation is used as the only input source, and the data delay increases with the decrease of the frame rate, the tracking loop bandwidth cannot obtain satisfactory results; compared with the traditional PID control, the weighted fusion tracking control method based on the tracking deviation and the gyro signal proposed by the technical solution of the present invention introduces more measurement data, and through reconstructing the tracking control loop, corrects the tracking delay as part of the disturbance, and obtains higher performance; the method of the present invention first measures the total delay of the video tracking control loop to obtain a linearized delay model, then combines the tracking deviation data and the gyro data to reconstruct a high-bandwidth tracking control loop, and generates a discretized reconstructed loop control command, and finally performs weighted fusion on the output commands of the original tracking control loop and the reconstructed tracking control loop to obtain the final tracking control command, thereby realizing high-bandwidth video tracking control.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) Compared with the prior art, the technical solution of the present invention can improve the tracking rapidity of the optoelectronic stabilization platform for maneuvering targets, and improve the isolation ability of the video tracking control loop to disturbances, which provides the possibility for the optoelectronic tracking and aiming system to continuously and stably track fast targets.

[0048] (2) The technical solution of the present invention can make the tracking control loop bandwidth of the optoelectronic tracking and aiming system reach 5Hz, and the tracking control performance is relatively ideal.

[0049] (3) The technical solution of the present invention can be realized by software, without the need to add additional hardware resources, and has high feasibility.

[0050] (4) The technical solution of the present invention has high generality and portability, and can be used on different types of optoelectronic tracking platforms.

[0051] (5) The present invention can increase the bandwidth of the tracking control loop of the optoelectronic tracking and aiming system, and also greatly improve the isolation ability of the tracking control loop against external disturbances. Description of the Drawings

[0052] Figure 1 It is a schematic diagram of the video tracking control loop of the optoelectronic tracking and aiming system involved in the technical solution of the present invention;

[0053] Figure 2 It is a schematic diagram of the implementation process of the technical solution of the present invention;

[0054] Figure 3 It is a weighted system curve;

[0055] Figure 4 It is a comparison diagram of the closed-loop frequency response curves of the original classical PID control and the method involved in the present invention. Detailed Embodiments

[0056] To make the objectives, content and advantages of the present invention clearer, the following further describes in detail the specific embodiments of the present invention with reference to the drawings and embodiments.

[0057] Embodiment 1

[0058] This embodiment is an optoelectronic tracking and aiming system on a certain type of helicopter. As Figure 1 shown is the composition diagram of the video tracking control loop of this system. The video tracker 1 in the optoelectronic tracking and aiming system generates a tracking control deviation based on the target angular position and the current aiming line, and sends it to the tracking controller 2. The tracking controller 2 and the data weighted fusion tracking controller 3 designed in this patent generate a speed control command through the adder 4, and send it to the speed control loop 5, thereby driving the optoelectronic tracking and aiming system to follow the target angular position. To implement the data weighted fusion tracking control function described in this patent, the implementation process is as Figure 2 shown, and the following steps are executed:

[0059] The first step is to measure and generate a delay model of the video tracking control loop. Here, the loop delay is set as τ 0 , and the loop delay model is G τ (s).

[0060] The above-mentioned first step further includes:

[0061] Step 1.1: Measure the delay of the video tracking control loop. For the output signal of the angular position sensor in the optoelectronic tracking and aiming system, the real-time performance is relatively high. If it is assumed that the output value of the angular position sensor at time t 0 is X, and the angular position output by the video tracker at time t 1 is also X, then the tracking delay is calculated as follows:

[0062] τ 0 = t 1 -t 0

[0063] Step 1.2: Establish a time-delay model and linearize it. According to control system theory, the transfer function of the time-delay model is expressed as follows:

[0064]

[0065] where s denotes the differential operator;

[0066] To be able to design using linear control theory methods, Taylor expansion is adopted here, and at the same time, the Pade formula is used for truncation processing. Finally, the second-order approximate linearized model of the time-delay link is as follows:

[0067]

[0068] Second step, reconstruct and generate a high-bandwidth tracking control loop according to the tracking control loop time-delay model and the tracking control loop model.

[0069] The second step described above further includes:

[0070] Step 2.1: Reconstruct the estimated angular position signal without time delay. To obtain the angular position of the optoelectronic tracking and aiming system in the inertial space, it is obtained here by integrating the inertial angular velocity sensor (i.e., gyro). Assume the estimated angular position signal without time delay is

[0071]

[0072] where ω g is the angular velocity measured by the gyro;

[0073] Step 2.2: Reconstruct the angular position estimation signal after time delay according to the measured time-delay model. This signal is obtained by superimposing the angular position signal in Step 1 with the time-delay model as follows:

[0074]

[0075] Step 2.3: Reconstruct the non-time-delay closed-loop control loop according to the tracking deviation output by the video tracker, the non-time-delay estimated angular position reconstructed in Step 1, and the time-delay estimated angular position reconstructed in Step 2. The tracking deviation output by the tracker is Δθ, then the estimated tracking deviation output after reconstruction can be expressed as:

[0076]

[0077] Step 2.4: Generate the tracking controller command for the reconstructed loop. To obtain the high-bandwidth reconstructed tracking control loop command, a suitable controller needs to be applied as follows:

[0078]

[0079] In the above formula, K is the loop gain coefficient, and Q(s) is the loop low-pass filter. Generally, a typical first-order or second-order low-pass filter can be selected to balance the bandwidth and noise suppression.

[0080] In the third step, a velocity feedforward control command is generated according to the tracking deviation and the reconstruction delay loop. Here, the target velocity angular position signal is obtained by adding the tracking deviation and the reconstruction delay loop, and the target velocity signal is obtained through a differential filter. The velocity feedforward control command is as follows:

[0081]

[0082] In the formula, K v is the gain of the velocity feedforward controller, and Q v (s) is the differential filter. Here, a first-order low-pass differentiator is selected as the differential filter, and other differential controllers with better performance can also be used.

[0083] In the fourth step, the reconstructed high-bandwidth tracking control loop is discretized, and a reconstruction command is generated. Here, the common bilinear transformation is used to obtain the discrete reconstructed tracking control loop. If the motion period of the tracking control loop is T, the above transfer function is transformed from the s-domain to the z-domain for discretization to obtain the digital controller and as follows:

[0084]

[0085]

[0086] In the fifth step, the reconstructed high-bandwidth tracking control loop and the original forward tracking control loop commands are weighted and fused and output. If the tracking control command of the original tracking control loop is assumed to be U 0 , then the control command generated by weighted fusion tracking is as follows:

[0087]

[0088] In the above formula, α is the weighting coefficient, and this weighting coefficient is dynamically adjusted according to the magnitude of the tracking deviation. Here, α = 0.2·(1 + 1 / cosh(C·Δθ)) is selected, and its typical characteristics are as shown in Appendix Figure 3 , satisfying the characteristics of small weighting for small deviations and large weighting for large deviations.

[0089] In this step, the control command output by the original tracking control loop and the control command output by the reconstructed tracking control loop are weighted and summed, so as to fuse and track the gyro data and the tracking deviation input data.

[0090] The above are only the preferred embodiments of the present invention. Figure 4 It shows a comparison diagram of the bandwidth of the tracking control loop of the original system in the embodiment and the bandwidth of the tracking control loop after adopting the method of the present invention. It can be seen that the method involved in the present invention can effectively improve the bandwidth of the tracking control loop. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A data weighted fusion tracking control method for an airborne optoelectronic tracking and aiming system, characterized in that, it includes the following steps: The first step is to measure the delay of the video tracking control loop and generate a model; The second step is to reconstruct and generate a high-bandwidth tracking control loop according to the tracking control loop delay model and the tracking control loop model; The third step is to generate a speed feedforward control command according to the tracking deviation and the reconstructed delay loop; The fourth step is to discretize the output of the reconstructed high-bandwidth tracking control loop and the feedforward control output, and generate a reconstructed command; The fifth step is to perform weighted fusion on the reconstructed high-bandwidth tracking control loop command, the feedforward control command, and the original forward tracking control loop command and output; In the first step, set the loop delay to τ 0 , and the loop delay model is G τ (s). Establish the delay model and obtain the approximate linearized model as follows: In the first step, the process of measuring the delay of the video tracking control loop and generating a model is as follows: Step 1.1: Measure the delay of the video tracking control loop Assume that at time t 0 the output value of the moment angle position sensor is X, and the angle position output by the video tracker at time t 1 is also X, then the tracking delay is calculated as follows: τ 0 = t 1 - t 0 Step 1.2: Establish a delay model and linearize it According to the control system theory, the transfer function of the delay model is expressed as follows: In the formula, s represents the differential operator; Using Taylor expansion and truncating with the pade formula, the second-order approximate linearized model of the delay link is finally obtained, that is, formula (1); In the second step, the process of generating a high-bandwidth tracking control loop is as follows: Step 2.1: Reconstruct the angular position signal without delay estimation; Step 2.2: Reconstruct the angular position estimation signal after delay according to the measured delay model; Step 2.3: Reconstruct the non-delay closed-loop control loop according to the tracking deviation output by the video tracker, the non-delay estimated angular position reconstructed in step 2.1, and the delayed estimated angular position reconstructed in step 2.2; Step 2.4: Generate the reconstructed loop tracking controller command; In Step 2.1, the angular position of the optoelectronic tracking and aiming system under inertial control is obtained through integration by an inertial angular velocity sensor. Let the angular position signal without delay estimation be where ω g is the angular velocity measured by the gyroscope; In step 2.2, the angular position estimation signal after delay is obtained by superimposing the angular position signal in step 1.1 and the delay model as follows: In step 2.3, the tracker outputs a tracking deviation of Δθ, and the estimated tracking deviation output after reconstruction is expressed as: In step 2.4, to obtain a high-bandwidth reconstructed tracking control loop command, apply a suitable controller: In the above formula, K is the loop gain coefficient, and Q(s) is the loop low-pass filter; In the third step, a speed feedforward control command is generated according to the tracking deviation and the reconstructed delay loop, and the speed feedforward control command is as follows: Here, K v is the feedforward controller gain, and Q v (s) is the differential filter; the target speed angular position signal is obtained by tracking the sum of the deviation and the reconstruction delay loop, and the target speed signal is obtained through the differential filter; In the fourth step, a discrete reconstructed tracking control loop is obtained by bilinear transformation. The control period of the tracking control loop is T, and the above transfer function is discretized from the s-domain to the z-domain to obtain a digital controller and as follows: In the fifth step, let the tracking control command of the original tracking control loop be U 0 , then the control command generated by weighted fusion tracking is as follows: In the above formula, α is the weighting coefficient, and this weighting coefficient is dynamically adjusted according to the size of the tracking deviation; In the fifth step, by performing weighted summation on the control command output by the original tracking control loop and the command output by the reconstructed tracking control loop, and outputting together with the feedforward control command, the gyro data and the tracking deviation input data are fused to form a new tracking control output.

Images