An apparatus and method for estimating the motion state of an aerial target based on laser ranging

Abstract

Embodiments of the present application disclose an apparatus and method for estimating the motion state of an aerial target based on laser ranging. The apparatus includes: a target tracking module, which is used to detect a target and track the detected target to obtain the motion state of the target; a laser distance prediction module, which is used to measure the round-trip transmission time of a laser signal to determine the target distance and predict and supplement the lost distance information to obtain a predicted laser distance value; an aerial target motion estimation module, which is used to obtain the motion state of the target in a reference coordinate system according to the laser distance information obtained by the laser distance prediction module, the motion state of the target, and the motion state of the target tracking module. The third-dimensional spatial information of the laser distance is introduced, and the influence of the motion state such as the attitude of the reconnaissance system is considered at the same time, effectively improving the anti-interference ability of the motion state estimation of the aerial target.

Description

Technical Field

[0001] The present application relates to the technical field of information processing, and particularly to an apparatus and method for estimating the motion state of an aerial target based on laser ranging. Background Art

[0002] Infrared target tracking technology is an important research direction in the field of computer vision and plays an important role in security fields such as positioning and navigation, target tracking, and traffic control. In practical applications, the indefinite movement of the target and the occlusion of complex backgrounds will greatly affect the effect of target tracking. Methods such as Kalman filtering and Meanshift model the target position information obtained by measurement to predict the target position information in subsequent processes. This type of target usually obtains position information in a two-dimensional space, without considering the position change of the device itself and the relative distance information between the device and the target. The time limit for target positioning and tracking is relatively high, and the accuracy is relatively low. The longer the target is lost, the greater the prediction deviation. When the target is occluded or lost, if the reconnaissance system itself undergoes a large movement change at the same time, the target prediction fails. Summary of the Invention

[0003] To solve or partially solve the above problems, the present application provides an apparatus and method for estimating the motion state of an aerial target based on laser ranging.

[0004] The present application proposes an apparatus for estimating the motion state of an aerial target based on laser ranging. The apparatus includes: a target tracking module, which is used to detect a target and track the detected target to obtain the motion state of the target; a laser distance prediction module, which is used to measure the round-trip transmission time of a laser signal to determine the target distance and predict and supplement the lost distance information to obtain a predicted laser distance value; and an aerial target motion estimation module, which is used to obtain the motion state of the target in a reference coordinate system according to the laser distance information obtained by the laser distance prediction module, the motion state of the target, and the motion state of the reconnaissance system.

[0005] In some examples, the target tracking module includes: a target detection module, which uses the local grayscale saliency feature of the target to suppress the background and highlight small targets, and then segments the target from the image through an adaptive threshold to achieve target detection and obtain the detection result; a multi-frame data association confirmation module, which processes the detection results of the target detection module for each frame in the image sequence, eliminates the interference that appears accidentally in a single frame, and calculates the correlation of the centroid position, area, and grayscale characteristics of the target in adjacent two frames through data association technology; when the correlation result meets a certain threshold, mark the association of these two frames, and when the cumulative number of associated frames exceeds the preset threshold, report its detected target; a Kalman filter tracking module, which uses a preset physical model to obtain the current state estimate and the current detection result to obtain the target state of the current frame and filters the influence of interference in target detection.

[0006] In some examples, the laser distance prediction module includes:

[0007] A short-term laser change rate calculation module, which calculates the change speed of the laser data in the recent N times;

[0008] A long-term laser change trend determination module, which calculates the change trend of the laser value in the recent N seconds.

[0009] In some examples, the aerial target motion estimation module includes: a prior information calculation module, which estimates the relative linear motion speed between the target and the reconnaissance system through the laser distance information; a real-time tracking information and laser distance information smoothing module, which eliminates the interference of abnormal measurement information on subsequent target prediction through one-dimensional Gaussian filtering and median filtering; a target motion estimation module, which selects a fixed reference coordinate system, then converts the coordinates of the target observed by the target tracking module to the reference coordinate system, and finally calculates the average motion speed of the moving target within a preset time period; an aerial target motion state post-processing module, which eliminates the interference of abnormal motion results through the prior information of the aerial target motion, and processes the estimation result by means of smoothing filtering according to the prior constraint that the short-term motion change of the aerial target is relatively slow to obtain the final aerial target motion speed.

[0010] In some examples, the target distance is measured by measuring the round-trip transmission time of the laser signal, and the lost distance information is predicted and supplemented to obtain the laser distance information, including: measuring the laser distance and judging whether there is a distance return value; if there is a laser distance measurement return value at the current moment, directly output the laser distance value to achieve target distance measurement; if the current laser distance measurement return value is 0 and the prediction condition is met, calculate the short-term laser change speed and the long-term laser change trend to obtain the predicted laser distance value.

[0011] In some examples, to obtain the motion state of the target in the reference coordinate system based on the laser distance information obtained by the laser distance prediction module, the motion state of the target, and the motion state of the detection system, it includes: obtaining the target azimuth, pitch, and laser distance value; calculating the linear relative velocity between the detection system and the target according to the laser distance information, and smoothing the sampled laser distance value using median filtering; smoothing the target azimuth and pitch using a smoothing module; performing position conversion in the reference coordinate system; calculating the velocity in each direction and the linear velocity in the reference coordinate system; smoothing the velocity; and outputting the target state.

[0012] This application also proposes a method for estimating the motion state of an aerial target based on laser ranging. The method includes: detecting the target and tracking the detected target to obtain the motion state of the target; measuring the round-trip transmission time of the laser signal to determine the target distance, and predicting and supplementing the lost distance information to obtain the predicted laser distance value; obtaining the motion state of the target in the reference coordinate system according to the laser distance information obtained by the laser distance prediction module, the motion state of the target, and the motion state of the detection system.

[0013] Compared with the prior art, this application has the following beneficial effects:

[0014] In the technical solution provided by this application, the device includes: a target tracking module for detecting the target and tracking the detected target to obtain the motion state of the target; a laser distance prediction module for measuring the round-trip transmission time of the laser signal to determine the target distance and predicting and supplementing the lost distance information to obtain the predicted laser distance value; an aerial target motion estimation module for obtaining the motion state of the target in the reference coordinate system according to the laser distance information obtained by the laser distance prediction module, the motion state of the target, and the motion state of the target tracking module. The third-dimensional spatial information of laser distance is introduced, and the influence of the motion state such as the attitude of the detection system is considered, effectively avoiding the interference of the self-motion of the detection system on the estimation of the target motion state and effectively improving the anti-interference ability of the estimation of the aerial target motion state; second, a laser distance prediction module is designed to reduce the dependence of the prediction system on laser distance measurement; third, the real-time tracking information and laser distance information smoothing module can effectively eliminate measurement interference and avoid calculation errors caused by signal capture delay of the detection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of the basic structure of an apparatus for estimating the motion state of an aerial target based on laser ranging shown in an embodiment of this application;

[0016] Figure 2It is a schematic diagram of a basic process for obtaining predicted laser distance information shown in an embodiment of the present application;

[0017] Figure 3 It is a schematic diagram of a basic process for obtaining the motion state of a target in a reference coordinate system shown in an embodiment of the present application. Detailed implementation manners

[0018] Here, exemplary embodiments will be described in detail, and examples thereof are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0019] The block diagrams shown in the drawings are only functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0020] The flowcharts shown in the drawings are only exemplary descriptions, and do not necessarily include all contents and operations / steps, nor do they necessarily need to be executed in the described order. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined. Therefore, the actual execution order may change according to the actual situation.

[0021] It should also be noted that: "a plurality of" mentioned in the present application means two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0022] Embodiment 1

[0023] Please refer to Figure 1 , Figure 1An apparatus for estimating the motion state of an airborne target based on laser ranging, as shown in an exemplary embodiment, includes: a target tracking module for detecting a target and tracking the detected target to obtain the motion state of the target; a laser distance prediction module for measuring the round-trip transmission time of a laser signal to determine the target distance and predicting and supplementing the lost distance information to obtain a predicted laser distance value; and an airborne target motion estimation module for obtaining the motion state of the target in a reference coordinate system based on the laser distance information obtained by the laser distance prediction module, the motion state of the target, and the motion state of the reconnaissance system.

[0024] It should be understood that laser ranging technology measures the round-trip transmission time of a laser signal to determine the target distance. Based on the real-time tracking of a moving target by a reconnaissance system, laser ranging technology can obtain the distance information of the target in real time. At this time, by combining the motion of the reconnaissance system (the apparatus for estimating the motion state of an airborne target based on laser ranging) itself, the target distance, and the distance change rate and other information, the motion information of the target can be calculated by establishing a reference coordinate system. When the target is lost, the relative displacements of the target in each direction in the reference coordinate system can be calculated based on the calculated motion information of the empty target, and finally the predicted position of the target can be obtained by combining the motion state of itself. During the target tracking process, the motion state of the reconnaissance system can also be adjusted accordingly. However, this calculation method has high requirements for target tracking stability and laser ranging accuracy. Therefore, it is of great significance to design a method for estimating the motion state of a target based on laser ranging.

[0025] In some examples, the target tracking module includes: a target detection module for suppressing the background and highlighting small targets by using the local gray saliency characteristics of the target, and then segmenting the target from the image through an adaptive threshold to achieve target detection and obtain a detection result; a multi-frame data association confirmation module for processing the detection results of the target detection module in each frame of the image sequence, removing the interference that appears accidentally in a single frame, and calculating the correlation of the centroid position, area, and gray characteristics of the target in adjacent two frames through data association technology; when the correlation result meets a certain threshold, marking the two frames as associated, and when the cumulative number of associated frames exceeds a preset threshold, reporting its detected target; and a Kalman filter tracking module for obtaining the target state of the current frame by using a preset physical model to obtain the current state estimate and the current detection result, and filtering the influence of interference in target detection.

[0026] In some examples, the laser distance prediction module includes:

[0027] A short-term laser change rate calculation module for calculating the change speed of the nearest N laser data.

[0028] A long-term laser change trend determination module, which is used to calculate the change trend of laser values in the recent N seconds.

[0029] It can be understood that the change speed of the recent N laser data is calculated by the short-term laser change rate calculation module; the change trend of the laser values in the recent N seconds is calculated by the long-term laser change trend determination module; given the change speed and change trend (increasing or decreasing) of the laser values, the laser distance value at subsequent times can be predicted.

[0030] In some examples, the aerial target motion estimation module includes: a prior information calculation module, which is used to estimate the relative linear motion speed between the target and the reconnaissance system through laser distance information; a real-time tracking information and laser distance information smoothing module, which is used to eliminate the interference of abnormal measurement information on subsequent target prediction through one-dimensional Gaussian filtering and median filtering; a target motion estimation module, which is used to select a fixed reference coordinate system, then convert the coordinates of the target observed by the target tracking module into the reference coordinate system, and finally calculate the average motion speed of the moving target within a preset time period; an aerial target motion state post-processing module, which is used to eliminate the interference of abnormal motion results through the prior information of aerial target motion, and according to the prior constraint that the short-term motion change of the aerial target is relatively slow, use a smoothing filtering method to process the estimation result to obtain the final aerial target motion speed.

[0031] In some examples, the target distance is measured by measuring the round-trip transmission time of the laser signal, and the missing distance information is predicted and supplemented to obtain the predicted laser distance information, such as Figure 1 shown, which includes: measuring the laser distance and judging whether there is a distance return value; when there is a laser distance measurement return value at the current moment, directly output the laser distance value to achieve target distance measurement; when the current laser distance measurement return value is 0 and the prediction condition is met, calculate the short-term laser change speed and the long-term laser change trend to obtain the predicted laser distance value.

[0032] Among them, the specific operation process of laser distance prediction is as follows:

[0033] 1. Set the laser prediction window size ws and the laser distance change threshold T v ; when the continuously acquired laser distance values meet the window size, the laser prediction module is started in real time;

[0034] 2. When there is a laser distance measurement return value at the current moment, directly output the laser value;

[0035] 3. When the current laser distance measurement return value is 0 (i.e., there is no laser return value), calculate the short-term laser change speed and the long-term laser change trend to obtain the laser distance prediction value;

[0036] 3a) Calculate the laser speed within the laser prediction window according to formula (1), where l t represents the laser distance value at time t, Vt represents the time difference between time t and the previous time, and V l t represents the laser speed at time t;

[0037]

[0038] 3b) Smoothly calculate the short-term change speed of the laser according to formula (2);

[0039]

[0040] 3c) Calculate the final predicted laser distance value according to formula (3) based on the long-term laser value change trend, where N represents the sampling time interval;

[0041]

[0042] In some examples, based on the laser distance information obtained by the laser distance prediction module, the motion state of the target, and the motion state of the detection system, the motion state of the target in the reference coordinate system is obtained. As Figure 3 shown, it includes: obtaining the target azimuth, pitch, and laser distance value; calculating the linear relative speed between the detection system and the target according to the laser distance information, and smoothing the sampled laser distance value using median filtering; smoothing the target azimuth and pitch using a smoothing module; reference coordinate system position conversion; calculation of the velocity and linear velocity in each direction of the reference coordinate system; velocity smoothing; outputting the target state. Specifically, the air target motion estimation module first selects a fixed reference coordinate system - the northeast celestial coordinate system, then converts the coordinates of the target observed by the detection system to the northeast celestial coordinates, and finally calculates the average motion speed (eastward, northward, and celestial components) of the moving target within the time periods T1 and T2; the air target motion state post-processing module first eliminates the interference of abnormal motion results based on the prior information of the air target motion, and processes the estimated results using a smoothing filtering method according to the prior constraint that the short-term motion of the air target changes slowly, to obtain the final air target motion speed (eastward, northward, and celestial components).

[0043] Among them, the specific algorithm operation flow of the air target motion state estimation method using laser ranging is as follows:

[0044] Set the sampling window L for the laser distance s , the sampling window T for the target motion azimuth and pitch s , and the post-processing sampling window P S ;

[0045] The prior information calculation module calculates the linear relative velocity between the reconnaissance system and the target based on the laser distance information, and smooths the sampled laser distance values using median filtering;

[0046] The smoothing module smooths the target azimuth and elevation within the sampling window;

[0047] Coordinate system conversion is performed through the target information (laser distance r, azimuth α, elevation β) and the attitude information of the reconnaissance system (heading angle φ, roll angle γ, pitch angle φ), and the coordinates of the target at each sampling moment (T1, KT N ) in the northeast celestial coordinate system are obtained respectively. The coordinate system conversion formulas are shown in Formulas (4) and (5), where x, y, and z represent the eastward, northward, and upward coordinates in the northeast celestial coordinate system respectively.

[0048]

[0049]

[0050] Calculate the relative motion speed between the target and the reconnaissance system at the current moment and record it in the speed sampling sequence. The specific calculation method is shown in Formula (6), where x t 、y t 、z t represent the eastward, northward, and upward coordinates at time t respectively, represent the relative motion speeds of the target and the reconnaissance system in the eastward, northward, and upward directions at time t respectively;

[0051]

[0052] When the sampling sequence meets the preset quantity, smooth the relative motion speeds in the sampled eastward, northward, and upward directions to obtain The smoothing is divided into two steps: first, complete the median filtering, and then calculate the mean value of the sequence;

[0053] Calculate the motion state of the target in the reference coordinate system. The calculation method is shown in Formula (7), where represent the eastward, northward, and upward speeds of the target at time t respectively, represent the eastward, northward, and upward speeds of the reconnaissance system at time t respectively;

[0054]

[0055] The above algorithm process is for the estimation of the target motion state under laser ranging conditions. Under the condition of completing the estimation of the target motion state, the position of the target is also estimated reversely through the motion information, that is, through the velocity-displacement formula displacement = velocity × time, the position of the target in the northeast celestial coordinate system is obtained, and then the azimuth and pitch information of the target in the current detection system is obtained through the transformation from the northeast celestial coordinate system to the device coordinate system.

[0056] This application adopts the above technical solutions to realize the estimation of the motion state of an airborne target. Compared with the two-dimensional space (azimuth, pitch) trajectory prediction, it has the following advantages: First, the third-dimensional space information of laser distance is introduced, and the influence of the motion state such as the attitude of the detection system is considered at the same time, effectively avoiding the interference of the self-motion of the detection system on the estimation of the target motion state, and effectively improving the anti-interference ability of the estimation of the airborne target motion state; Second, a laser distance prediction module is designed to reduce the dependence of the prediction system on laser distance measurement; Third, the real-time tracking information and laser distance information smoothing module can effectively eliminate measurement interference and avoid calculation errors caused by the delay of the detection system.

[0057] This application also proposes a method for estimating the motion state of an airborne target based on laser ranging. The method includes: detecting the target and tracking the detected target to obtain the motion state of the target; measuring the round-trip transmission time of the laser signal to achieve target distance measurement, and predicting and supplementing the lost distance information to obtain the predicted laser distance value; obtaining the motion state of the target in the reference coordinate system according to the laser distance information obtained by the laser distance prediction module, the motion state of the target, and the motion state of the detection system.

[0058] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above-described devices and units can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated herein.

[0059] In the several embodiments provided by this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0060] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiments of the present invention.

[0061] In addition, in each embodiment of the present invention, the functional units may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of a software functional unit.

[0062] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it may be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, may be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in the various embodiments of the present invention. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0063] The technical solutions provided by the embodiments of the present invention have been introduced in detail above. Specific examples are used in this patent to elaborate on the principles and implementation manners of the embodiments of the present invention. The description of the above embodiments is only applicable to helping understand the principles of the embodiments of the present invention; the above is only the preferred embodiment of the present invention and is not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An air target motion state estimation device based on laser ranging, characterized in that The device includes: A target tracking module, which is used to detect a target and track the detected target to obtain the motion state of the target; A laser distance prediction module, which is used to measure the round-trip transmission time of a laser signal to determine the target distance and predict and supplement the lost distance information to obtain a predicted laser distance value; An airborne target motion estimation module, which is used to obtain the motion state of the target in the reference coordinate system according to the laser distance information obtained by the laser distance prediction module, the motion state of the target, and the motion state of the reconnaissance system; The method of measuring the round-trip transmission time of a laser signal to determine the target distance and predicting and supplementing the lost distance information to obtain a predicted laser distance value includes: Performing laser ranging and determining whether there is a distance return value; If there is a laser ranging return value at the current moment, directly output the laser distance value to achieve target distance determination; If the current laser ranging return value is 0 and the prediction condition is met, calculate the short-term laser change speed and the long-term laser change trend to obtain a predicted laser distance value.

2. The device according to claim 1, characterized in that, The target tracking module includes: A target detection module, which is used to suppress the background and highlight small targets by using the local gray saliency characteristics of the target, and then segment the target from the image through an adaptive threshold to achieve target detection and obtain a detection result; A multi-frame data association confirmation module, which is used to process the detection results of the target detection module for each frame of the image sequence, eliminate the interference that appears accidentally in a single frame, and calculate the correlation of the centroid position, area, and gray characteristics of the target in adjacent two frames through data association technology; when the correlation result meets a certain threshold, mark the two frames as associated, and when the cumulative number of associated frames exceeds the preset threshold, report its detected target; A Kalman filter tracking module, which uses a preset physical model to obtain the current state estimate and the current detection result to obtain the target state of the current frame and filter the influence of interference in target detection.

3. The device according to claim 1, characterized in that, The laser distance prediction module includes: A short-term laser change rate calculation module, which is used to calculate the change speed of the laser distance values in the recent N times according to the following formula: Among them, ws represents the laser prediction window size; T v represents the laser distance change threshold; l t represents the laser distance value at time t, and Δt represents the time difference between time t and the previous moment, represents the change speed of the laser distance value at time t; A long-term laser change trend determination module, which is used to calculate the change trend of the laser distance values in the recent N seconds, and the change trend includes increasing or decreasing.

4. The device according to claim 1, characterized in that, The airborne target motion estimation module includes: A prior information calculation module, which is used to estimate the relative linear motion speed between the target and the reconnaissance system through laser distance information; A real-time tracking information and laser distance information smoothing module, which is used to eliminate the interference of abnormal measurement information on subsequent target prediction through one-dimensional Gaussian filtering and median filtering; A target motion estimation module, which is used to select a fixed reference coordinate system, then convert the coordinates of the target observed by the target tracking module to the reference coordinate system, and finally calculate the average motion speed of the moving target within a preset time period; An airborne target motion state post - processing module is used to eliminate the interference of abnormal motion results through the prior information of airborne target motion. According to the prior constraint that the motion of the airborne target changes slowly in a short time, a smoothing filtering method is adopted to process the estimation result to obtain the final motion speed of the airborne target.

5. The device according to claim 1, characterized in that, It is used to obtain the motion state of the target in the reference coordinate system according to the laser distance information obtained by the laser distance prediction module, the motion state of the target, and the motion state of the reconnaissance system, including: Obtain the target azimuth, pitch, and laser distance value; Calculate the linear relative speed between the reconnaissance system and the target according to the laser distance information, and smooth the sampled laser distance value using median filtering; Use a smoothing module to smooth the target azimuth and pitch; Reference coordinate system position conversion; Calculate the velocity in each direction and the linear velocity of the reference coordinate system; Velocity smoothing; Output the target state.

6. A method for estimating the motion state of an aerial target based on laser ranging, characterized in that, The method includes: Detect the target and track the detected target to obtain the motion state of the target; Measure the round - trip transmission time of the laser signal to achieve target distance measurement, and predict and supplement the lost distance information to obtain the predicted laser distance value; Obtain the motion state of the target in the reference coordinate system according to the laser distance information, the motion state of the target, and the motion state of the reconnaissance system; The measurement of the target distance by measuring the round - trip transmission time of the laser signal and the prediction and supplement of the lost distance information to obtain the predicted laser distance value include: Perform laser ranging and determine whether there is a distance return value; If there is a laser ranging return value at the current moment, directly output this laser distance value to achieve target distance measurement; If the current laser ranging return value is 0 and the prediction condition is met, calculate the short - time laser change speed and the long - time laser change trend to obtain the predicted laser distance value.

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