Target automatic tracking method and system based on satellite laser ranging echo signal

Abstract

The invention discloses an automatic target tracking method and system based on satellite laser ranging echo signals, and the method comprises the steps: S1, carrying out the space scanning of an uncertain domain of a ranging target through employing a regular hexagon dense scanning strategy, and completing the searching and capturing of the target; s2, after the target is captured, correcting the direction of the telescope by dynamically switching a global optimization mode and a local optimization mode by adopting a miss distance optimization method combining a Bayesian optimization algorithm and a local optimization algorithm, so as to complete the optimization of the miss distance; s3, target tracking is carried out based on the optimized miss distance, and echo signal intensity is monitored in real time; and S4, judging whether the signal is attenuated or not, re-triggering the miss distance optimization process when detecting that the signal is attenuated, and otherwise, maintaining the current tracking state.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser ranging, in particular, to a target automatic tracking method and system based on satellite laser ranging echo signals. BACKGROUND

[0002] Laser ranging is a high-precision space target observation method, which measures the distance by emitting laser and recording the time of flight of laser pulses. At present, satellite laser ranging experiments mostly rely on test personnel to adjust the ranging target to the center of the field of view according to the monitoring camera. When the ranging target is in strong sunlight background or is blocked by the Earth's shadow, it is impossible to correct the pointing of the telescope through the monitoring camera.

[0003] When satellite laser ranging experiments are carried out on such invisible targets, the test personnel can only rely on their past experience to carry out "blind search" on the ranging target. This "blind search" not only takes a long time, but also makes it difficult to ensure the capture of the ranging target. For the automatic capture and tracking scheme of the present ranging target, the main methods are image processing method, centroid algorithm and echo signal method.

[0004] The image processing method refers to obtaining the deviation value between the ranging target and the center of the field of view (or the laser scattering light tip) through image processing method. When positioning the ranging target, vector boundary scanning method, least square method and Hough transform method are usually used. The positioning of the laser light tip and the target is then converted into the target miss distance. However, under strong noise background conditions, the image processing method has certain limitations. Strong noise will interfere with the acquisition of image information, resulting in positioning errors due to inaccurate extraction of target features. In addition, the laser light tip presented in the monitoring camera is formed by atmospheric scattering. When the weather is extremely clear, the scattering intensity of the laser is low, and it may not be possible to observe the obvious laser light tip in the monitoring camera. Moreover, when the target is in the Earth's shadow, the ranging target cannot be illuminated by the sun, and the target cannot be observed in the monitoring camera. In summary, the image processing method will be limited by weather conditions and target illumination in actual application scenarios.

[0005] The centroid algorithm adopts a single-photon sensitive four-quadrant detector, and according to the real-time data processing results of each channel, the pointing deviation of the telescope in the ranging process is corrected by using the centroid algorithm. When the centroid algorithm is used to adjust the pointing of the telescope, the detector must use spatial light coupling to ensure that the miss distance solved by the centroid algorithm is correct and effective. Because spatial light coupling can make light propagate and receive in an ideal state, the signal strength received by each channel is closely related to the actual position of the target, thereby providing a reliable data basis for the accurate solution of the centroid algorithm. On the contrary, if the optical fiber coupling method is used, multiple reflections of incident light will occur in the optical fiber. This complex reflection process will seriously interfere with the propagation path of light and the signal strength received by each channel. Ultimately, the system cannot solve the centroid algorithm only according to the signal strength of each channel, greatly reducing the accuracy and reliability of the telescope pointing correction.

[0006] Based on the automatic closed-loop tracking of satellite laser ranging echo signals, a two-stage spiral scanning strategy is usually adopted: first, a large-scale spiral scan is performed to achieve target acquisition; then, a small-scale spiral scan is used to finely adjust the pointing of the telescope and optimize the miss distance; and finally, target tracking is performed according to the optimization result of the miss distance, so that the SLR echo signal is maintained at a high level. Although this method is simple, easy to implement and can avoid the case where the ranging target is in strong background noise and earth shadow, its optimization efficiency for the miss distance is low, and the global optimal solution of the miss distance can be determined only after comprehensive sampling of the entire optimization domain.

[0007] The automatic closed-loop tracking technology based on satellite laser ranging echo signals can completely avoid the influence of whether the target is visible, and is an effective way to solve the problem of invisible satellite laser ranging. However, the current miss distance optimization method of this technology still has the problems of low optimization efficiency and easy to fall into local optimum.

[0008] A laser ranging system telescope pointing deviation automatic correction method is disclosed in Chinese patent application No. 202410561225.8, which includes the following steps: obtaining an observation target image; collecting laser backscattering light tips and calculating the miss distance of the laser light tips relative to the center of the field of view to fine-tune the light path; when the observation target is visible, obtaining the pixel deviation amount of the laser light tips and the satellite centroid, converting the pixel deviation into an angle deviation, adjusting the pointing of the telescope to make the satellite centroid coincide with the laser light tips; and locking the laser light direction to the center of the field of view; when the observation target is not visible, real-time correction of the satellite prediction is performed, and the grating spiral search method is used to search for the invisible target. The technical solution of the present application ensures the parallelism of the telescope receiving and transmitting light axis by constructing a receiving and transmitting light path correction method, and realizes the automatic correction of the telescope pointing error by combining image processing technology and target search algorithm. The prior art does not provide a specific solution for the optimization of miss distance. SUMMARY

[0009] To solve the technical problems in the background art, the present application provides a target automatic tracking method based on satellite laser ranging echo signals, which includes: S1: using a regular hexagon dense packing scanning strategy to perform spatial scanning on the uncertainty domain of the ranging target to complete target search and capture; S2: after capturing the target, using a miss distance optimization method combining the Bayesian optimization algorithm and the local optimization algorithm to correct the pointing of the telescope by dynamically switching between global and local optimization modes, thereby optimizing the miss distance; S3: based on the optimized miss distance, performing target tracking and monitoring the echo signal strength in real time; S4: determining whether the signal is attenuated, and if the signal attenuation is detected, retriggering the miss distance optimization process, otherwise maintaining the current tracking state.

[0010] As a preferred scheme, the method of using a regular hexagon dense packing scanning strategy to perform spatial scanning on the uncertainty domain of the ranging target to complete target search and capture includes: A circle with a radius R is used to represent the uncertainty domain of the search, the effective area of a single step scanning is set as a unit circle, and the radius of the effective area of a single step scanning is defined as the scanning step size r , the number of dense packing layers and the single step duration are set as n and ΔT The total number of scanning steps R is determined according to the relationship between the uncertainty domain radius r , the scanning step size n and the number of dense packing layers N , and the total scanning duration ΔT is calculated based on the single step duration T, complete the capture of the ranging target, and the specific formula is: radius of the uncertainty domain R and the search step r and the number of densely packed layers n relationship:

[0011] total number of scanning steps N and the number of densely packed layers n relationship:

[0012] total scanning time T when the hexagonal dense packing is performed and the scanning uncertainty domain R and the search step r relationship: .

[0013] As a preferred solution, after capturing the target, a miss distance optimization method combining the Bayesian optimization algorithm and the local optimization algorithm is adopted, and the telescope pointing is corrected by dynamically switching the global and local optimization modes, so as to complete the optimization of the miss distance. The method comprises: adopting the Bayesian optimization algorithm to perform global search within the optimization uncertainty domain expanded to 1.5 times the effective area of a single scan; According to the preset switching logic, the global search and local search optimization modes are dynamically switched to correct the telescope pointing until the preset convergence condition is met, and the optimal miss distance parameter is obtained.

[0014] As a preferred solution, the preset switching logic comprises: When the echo signal strength reaches the preset threshold, the local optimization algorithm is triggered to perform local search; If the echo signal strength is lower than the preset threshold during the local optimization process, the Bayesian optimization algorithm is restarted to perform global search.

[0015] As a preferred solution, the calculation method of the preset threshold comprises: obtain the echo photon response number without pointing error through the pointing increment laser ranging equation; The echo photon response number without pointing error is multiplied by a preset attenuation coefficient to obtain the preset threshold, wherein the attenuation coefficient is used to correct the influence of weather and laser energy fluctuation.

[0016] As a preferred solution, the preset convergence condition comprises: When the current solution corresponding to the target function value , it is determined to be converged, wherein is the domain of , is a neighborhood any one of the sampling points, is a sampling point corresponding to the objective function value.

[0017] As a preferred solution, the method comprises the following steps of: judging whether the signal is attenuated; when detecting the signal attenuation, re-triggering the miss distance optimization process; otherwise, maintaining the current tracking state. According to the detected signal, a signal intensity change curve is obtained, and the signal intensity change curve is fitted by a least square method; when the curve slope is less than a preset value, it is determined that the signal is attenuated.

[0018] The second aspect of the present application provides a target automatic tracking system based on satellite laser ranging echo signals, the system comprising a target search module, a miss distance optimization module, a tracking monitoring module and an attenuation judgment module. The target search module is used to adopt a regular hexagon dense scanning strategy to perform spatial scanning on the uncertain domain of the ranging target, and complete target search and capture. The miss distance optimization module is used to adopt a miss distance optimization method combining a Bayesian optimization algorithm and a local optimization algorithm after capturing the target, and correct the telescope pointing by dynamically switching the global and local optimization modes, so as to complete the optimization of the miss distance. The tracking monitoring module is used to track the target based on the optimized miss distance, and monitor the echo signal intensity in real time. The attenuation judgment module is used to judge whether the signal is attenuated; when detecting the signal attenuation, re-triggering the miss distance optimization process; otherwise, maintaining the current tracking state.

[0019] The third aspect of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to realize the steps of the foregoing target automatic tracking method based on satellite laser ranging echo signals.

[0020] The fourth aspect of the present application provides a computer device, which comprises a storage medium, a processor and a computer program stored in the storage medium and executable by the processor, and the computer program is executed by the processor to realize the steps of the foregoing target automatic tracking method based on satellite laser ranging echo signals.

[0021] Compared with the prior art, the present application has the beneficial effects that: The present application proposes a miss distance optimization scheme combining a Bayesian optimization algorithm and a local optimization algorithm, which has strong tolerance to sky background noise and can realize daytime satellite laser ranging. In addition, the present application improves the global optimization efficiency while ensuring the intensity of the satellite laser ranging echo signal in the local optimization stage. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A target automatic tracking method based on satellite laser ranging echo signal is provided for the embodiment; Figure 2 A regular hexagon close packing diagram is provided for the embodiment; Figure 3 A miss distance optimization flow chart is provided for the embodiment. DETAILED DESCRIPTION The drawings are merely schematic and are non-limiting examples of the application; It should be clear that the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0023] The terms used in the present application are merely for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein means and includes any or all possible combinations of one or more associated listed items.

[0024] The following description relates to the drawings, where the same numbers on different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments are not meant to represent all implementations consistent with the present application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the present application as detailed in the appended claims. In the description of the present application, it should be understood that the terms "first", "second", "third", etc. are used only to distinguish similar objects, and do not necessarily indicate a specific order or sequence, nor can they be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0025] In addition, in the description of the present application, "multiple" means two or more, unless otherwise specified. The association between the associated objects is described by "and / or", which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. The character " / " generally represents a "or" relationship between the associated objects. The present application is further described below in conjunction with the drawings and examples.

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Example 1 Please refer to Figure 1 This embodiment provides an automatic target tracking method based on satellite laser ranging echo signals, the method comprising: S1: A regular hexagonal tessellation scanning strategy is used to spatially scan the uncertainty domain of the ranging target to complete the target search and acquisition; It should be noted that the spatial uncertainty region of the scan is usually larger than the divergence angle of the laser beam, meaning the laser beam needs to scan the spatial uncertainty region along a specific path. The scanning search process for the ranging target can be equivalent to a planar tessellation problem, and the search trajectory can be solved based on the planar tessellation.

[0028] Please refer to Figure 2 , Figure 2 To illustrate the search trajectory obtained from the tessellation of regular hexagons, the solid lines in the diagram represent the inscribed regular hexagons of the light spot. Dashed lines indicate the target search path, and the large circle represents the uncertainty region of the target search. The schematic diagram uses a circle with a radius of 11 to characterize the uncertainty region of the search, setting the effective area of ​​a single-step scan as the unit circle, and defining the radius of the effective area of ​​a single-step scan as the scan step size.

[0029] In one specific embodiment, the method for spatially scanning the uncertainty domain of the ranging target using a regular hexagonal tessellation scanning strategy to complete target search and acquisition includes: The uncertainty region of the search is represented by a circle of radius R. The effective region of a single-step scan is set as the unit circle, and the radius of the effective region of a single-step scan is defined as the scan step size. r The number of tessellation layers and the single-step duration were set respectively. n and ΔT According to the radius of the uncertainty region R Scan step size r With the number of tessellation layers n The relationship determines the total number of scan steps N And based on single-step duration ΔT Calculate total scan time T The target acquisition for ranging is completed using the following formula: Depend on Figure 2 It can be seen that the number of hexagons in the outermost layer is exactly the number of layers in the tessellation (the central regular hexagon is the first layer), from which the radius of the uncertainty region can be obtained. R and search step size r With the number of tessellation layers n Relationship:

[0030] According to the scanning path, it can be known that the first layer has only 1 step, 6 steps are needed to scan the second layer, and 12 steps are needed to scan the third layer, so the total number of scanning steps can be obtained N The relationship between the number of densely laid layers n The total scanning time T of the hexagonal dense packing and the scanning uncertainty domain

[0031] and the scanning step length R r

[0032] S2: After capturing the target, a deflection amount optimization method combining Bayesian optimization algorithm and local optimization algorithm is adopted, and the telescope pointing is corrected by dynamically switching global and local optimization modes, so as to complete the optimization of the deflection amount; It should be noted that the Bayesian optimization algorithm (BO) can efficiently improve the solution by modeling the target function through constructing a prediction model under limited evaluation times. The advantage of the local optimization algorithm is that it is simple to implement and has high computational efficiency, and can quickly find a local optimal solution in the search space. Therefore, when optimizing the deflection amount parameters, the BO and local optimization algorithm are combined, and the global search efficiency and signal strength are considered. This not only improves the efficiency of global optimization of the deflection amount, but also ensures that the return intensity of satellite laser ranging is maintained at a high level during the local optimization process.

[0033] In one specific embodiment, please refer to Figure 3 After capturing the target, a deflection amount optimization method combining Bayesian optimization algorithm and local optimization algorithm is adopted, and the telescope pointing is corrected by dynamically switching global and local optimization modes, so as to complete the optimization of the deflection amount, which comprises: The Bayesian optimization algorithm is used for global search within the optimization uncertainty domain which is expanded to 1.5 times the effective area of a single scan; According to the preset switching logic, the global search and local search optimization modes are dynamically switched to correct the telescope pointing until the preset convergence condition is met, and the optimal deflection amount parameters are obtained.

[0034] In one specific embodiment, the preset switching logic comprises: When the return signal strength reaches the preset threshold, the local optimization algorithm is triggered for local search; If the return signal strength is lower than the preset threshold during the local optimization process, the Bayesian optimization algorithm is restarted for global search.

[0035] ​​​In one specific embodiment, the method for calculating the preset threshold value comprises: obtaining the number of echo photons without pointing error by pointing to the incremental laser ranging equation; multiplying the number of echo photons without pointing error by a preset attenuation coefficient to obtain the preset threshold value, wherein the attenuation coefficient is used to correct the influence of weather and laser energy fluctuation.

[0036] In one specific embodiment, the preset convergence condition comprises: convergence is determined when the current solution the corresponding target function value is determined, wherein is the field of any one sampling point in the neighborhood the target function value corresponding to the sampling point .

[0037] S3: target tracking based on the optimized off-target amount, real-time monitoring of echo signal intensity; S4: determining whether the signal is attenuated, when signal attenuation is detected, retriggering the off-target amount optimization process, otherwise maintaining the current tracking state; In one specific embodiment, the method for determining whether the signal is attenuated, when signal attenuation is detected, retriggering the off-target amount optimization process, otherwise maintaining the current tracking state comprises: obtaining a signal intensity change curve according to the detected signal, fitting the signal intensity change curve by least square method, and determining that the signal is attenuated when the curve slope is less than a preset value.

[0038] Embodiment 2 The embodiment provides a target automatic tracking system based on satellite laser ranging echo signal, which comprises a target search module, an off-target amount optimization module, a tracking monitoring module and an attenuation judgment module. The target search module is used to perform spatial scanning on the uncertain field of the ranging target by adopting a regular hexagon dense packing scanning strategy, and complete target search and capture. The off-target amount optimization module is used to adopt an off-target amount optimization method combining the Bayesian optimization algorithm and the local optimization algorithm after capturing the target, correct the telescope pointing by dynamically switching the global and local optimization modes, thereby completing the optimization of the off-target amount. The tracking monitoring module is used to perform target tracking based on the optimized off-target amount, and real-time monitoring of echo signal intensity. The attenuation judgment module is used to determine whether the signal is attenuated, when signal attenuation is detected, retriggering the off-target amount optimization process, otherwise maintaining the current tracking state.​

[0039] Embodiment 3 The embodiment provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement steps of a target automatic tracking method based on satellite laser ranging echo signals according to the embodiment 1.

[0040] Embodiment 4 The embodiment provides a computer device, which comprises a storage medium, a processor and a computer program stored in the storage medium and executable by the processor, and the computer program is executed by the processor to implement steps of a target automatic tracking method based on satellite laser ranging echo signals according to the embodiment 1.

[0041] Obviously, the above embodiments of the present application are merely exemplary and are not intended to limit the present application. Based on the above description, those skilled in the art can make further modifications and variations without departing from the spirit and principle of the present application. It is not necessary or possible to enumerate all the embodiments. Any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A target automatic tracking method based on satellite laser ranging echo signals, characterized in that, The method comprises: S1: adopting a regular hexagon dense scanning strategy to perform spatial scanning on an uncertain domain of a ranging target, and completing target search and capture; S2: after capturing the target, adopting a miss distance optimization method combining a Bayesian optimization algorithm and a local optimization algorithm, and correcting the pointing of the telescope by dynamically switching global and local optimization modes, so as to complete optimization of the miss distance; S3: performing target tracking based on the optimized miss distance, and monitoring echo signal strength in real time; S4: judging whether the signal is attenuated, and when detecting signal attenuation, retriggering the miss distance optimization process, otherwise maintaining the current tracking state.

2. The method according to claim 1, wherein, The method for adopting a regular hexagon dense scanning strategy to perform spatial scanning on an uncertain domain of a ranging target, and completing target search and capture comprises: An uncertainty domain of the search is represented by a circle with a radius R, an effective area of the single-step scanning is set as a unit circle, and a radius of the effective area of the single-step scanning is defined as a scanning step length r , the number of densely packed layers and the single-step duration are respectively set as n and ΔT According to the uncertain domain radius R , the scanning step r and the relationship between the dense layer number n to determine the total scanning step number N , and based on the single step duration ΔT to calculate the total scanning duration T , complete the capture of the ranging target, the specific formula is: radius of uncertainty domain R and search step r relationship with the number of dense layers n ​ Total number of scanning steps N Relationship with the number of densely packed layers n : The relationship between the total scanning time T when the regular hexagons are densely packed and the scanning uncertainty domain R and the scanning step length r ​ 。 3. The method according to claim 1, characterized in that, The method for, after capturing the target, adopting a miss distance optimization method combining a Bayesian optimization algorithm and a local optimization algorithm, and correcting the pointing of the telescope by dynamically switching global and local optimization modes, so as to complete optimization of the miss distance comprises: adopting the Bayesian optimization algorithm to perform global search in an optimization uncertain domain expanded to 1.5 times the effective area of a single scan; correcting the pointing of the telescope according to a preset switching logic to dynamically switch global and local search optimization modes until a preset convergence condition is met, and obtaining optimal miss distance parameters.

4. The method according to claim 3, characterized in that, The preset switching logic comprises: when the echo signal strength reaches a preset threshold, triggering the local optimization algorithm to perform local search; if the echo signal strength is lower than the preset threshold during the local optimization process, restarting the Bayesian optimization algorithm to perform global search.

5. The method according to claim 4, characterized in that, The calculation method of the preset threshold comprises: obtaining echo photon response numbers without pointing errors through a pointing increment laser ranging equation; multiplying the echo photon response numbers without pointing errors by a preset attenuation coefficient to obtain the preset threshold, wherein the attenuation coefficient is used to correct the influence of weather and laser energy fluctuation.

6. The method according to claim 3, characterized in that, The preset convergence condition comprises: when the current solution corresponding objective function value is determined to converge, wherein is a domain, is a neighborhood of any one sampling point, is a sampling point corresponding objective function value.

7. The method according to claim 1, wherein, The method for judging whether the signal is attenuated, and when detecting signal attenuation, retriggering the miss distance optimization process, otherwise maintaining the current tracking state comprises: obtaining a signal strength change curve according to the detected signal, fitting the signal strength change curve through a least square method, and when the curve slope is less than a preset value, determining that the signal is attenuated.

8. A target automatic tracking system based on satellite laser ranging return signals, characterized in that, The system comprises a target search module, a miss distance optimization module, a tracking monitoring module, and an attenuation judgment module; The target search module is configured to adopt a regular hexagon dense scanning strategy to perform spatial scanning on an uncertain domain of a ranging target, and complete target search and capture; The miss distance optimization module is configured to, after capturing the target, adopt a miss distance optimization method combining a Bayesian optimization algorithm and a local optimization algorithm, and correct the pointing of the telescope by dynamically switching global and local optimization modes, so as to complete optimization of the miss distance; The tracking monitoring module is configured to perform target tracking based on the optimized miss distance, and monitor echo signal strength in real time; The attenuation judgment module is configured to judge whether the signal is attenuated, and when detecting signal attenuation, retrigger the miss distance optimization process, otherwise maintain the current tracking state.

9. A computer readable storage medium having stored thereon a computer program, characterized in that: The computer program is executed by the processor to implement the steps of the satellite laser ranging echo signal based target automatic tracking method according to any one of claims 1 to 7.

10. A computer device, comprising: The computer program is executed by the processor to implement the steps of the satellite laser ranging echo signal based target automatic tracking method according to any one of claims 1 to 7.

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