阅读说明：本技术 高分辨传感器弱小多目标检测前跟踪方法 (Tracking method before weak and small multi-target detection of high-resolution sensor ) 是由 谭顺成 康勖萍 宋伟健 于洪波 于 2020-12-01 设计创作，主要内容包括：本发明公开了一种高分辨传感器弱小多目标检测前跟踪方法,属于信息融合领域,适应于高分辨传感器对多个弱小目标的检测与跟踪。在对高分辨传感器数据进行处理时,基于TBD技术的弱小目标检测跟踪方法存在目标个数估计明显虚多、算法复杂度和计算显著增大,以及目标出现漏检时滤波器中代表该目标的粒子群迅速退化等问题。本发明提出的高分辨传感器弱小多目标检测前跟踪方法立足于解决此类问题。本发明通过对“同源”目标进行有效划分与融合,将源于同一目标的估计值进行融合处理,并通过在主滤波器中构建漏检目标辅助搜索机制,克服了基于TBD技术的弱小目标检测跟踪方法的局限性,因此具有较强的工程应用价值和推广前景。(The invention discloses a method for tracking a plurality of small and weak targets before detection by a high-resolution sensor, belongs to the field of information fusion, and is suitable for detecting and tracking a plurality of small and weak targets by the high-resolution sensor. When high-resolution sensor data are processed, the weak and small target detection and tracking method based on the TBD technology has the problems that the number of targets is obviously estimated, the algorithm complexity and calculation are obviously increased, particle swarms representing the targets in a filter are rapidly degraded when the targets are missed, and the like. The method for tracking the small and weak multiple targets of the high-resolution sensor before detection is based on solving the problems. The method effectively divides and fuses the homologous targets, fuses the estimated values from the same target, and constructs a missing target auxiliary search mechanism in the main filter, so that the method overcomes the limitation of the small and weak target detection tracking method based on the TBD technology, and has strong engineering application value and popularization prospect.)

1. The method for tracking the small and weak multiple targets of the high-resolution sensor before detection is characterized by comprising the following steps of:

step 1: system initialization

And constructing a main filter based on probability hypothesis density filtering, performing initialization processing on the filter, and constructing a missing detection target set and initializing the missing detection target set into an empty set.

Step 2: sensor measurement acquisition

Acquiring weak and small multi-target measurement data of non-threshold processing of the high-resolution sensor at the current moment, performing A/D conversion, and sending the data to a data processor;

and step 3: missing target assisted search particle set generation

If the missed detection target set is an empty set, directly turning to the step 4; otherwise, firstly, any target in the missed detection target set is predicted in one step to obtain a predicted value of the target state at the current moment, then, the predicted value is taken as a mean value, a target measurement error covariance is taken as a variance, multidimensional normal distribution is constructed, sampling is carried out from the normal distribution to be used for assisting in searching the auxiliary searching particle set of the missed detection target, finally, the auxiliary searching particle sets of all the missed detection targets are added to the main filter, the correction of the main filter is completed, and the missed detection target set is reset to be an empty set.

And 4, step 4: measuring coarse filtering

Filtering the measured data of the sensor by using the corrected main filter to obtain the rough number of targets and state estimation, wherein the state estimation comprises the estimation of the position and the speed of the targets;

and 5: "homologous" object partitioning and fusion

Comprehensively utilizing the flight paths of all targets to divide and fuse the rough target state estimation for the homologous targets, and correcting the number of the targets and the target state estimation;

step 6: target track management

Performing track maintaining, upgrading, degrading and canceling operations on the confirmed track, the tentative track, the possible track and the track head, and outputting information of each target track at the current moment;

and 7: and (5) turning to the next moment, and repeating the step (2) to the step (7) until the sensor is turned off.

2. The method for tracking the high-resolution sensor before weak and small multiple targets detection as claimed in claim 1, wherein the step 5 specifically comprises:

1) performing one-step prediction on each determined track, each tentative track and each possible track existing at the previous moment to obtain a predicted value of each track, establishing an elliptical wave gate according to the prediction covariance, and establishing an annular wave gate according to the target minimum and maximum possible speeds for the track head existing at the previous moment;

2) for any rough target state estimate, if the state estimate is

(1) Defining the state estimation as a track head without any elliptic wave gate or circular wave gate;

(2) if the state estimation only falls into the elliptic wave gate of a certain confirmed track, the state estimation is considered to be originated from the confirmed track, and the state estimation is divided into 'homologous' targets of the confirmed track;

(3) if the state estimation only falls into the elliptic wave gate of a certain tentative track, the state estimation is considered to be originated from the tentative track, and the state estimation is divided into a homologous target of the tentative track;

(4) if the estimated state only falls into the elliptic wave gate of a certain possible track, the estimated state is considered to be originated from the possible track and is divided into the 'homologous' targets of the possible track;

(5) if the state estimation only falls into the ring wave gate of a certain track head, the state estimation is considered to be originated from the track head, and the state estimation is divided into 'homologous' targets of the track head;

(6) if the target falls into a plurality of elliptical wave gates or ring wave gates at the same time, calculating the motion direction of the target according to target speed information contained in the state estimation, and dividing the motion direction into a confirmation track, a temporary track, a possible track or a homologous target of a track head, wherein the included angle between the target course and the motion direction of the target is the minimum;

3) and performing weighted fusion on the homologous targets of each confirmed track, each tentative track, each possible track and each track head by using a probability data interconnection method to obtain the state estimation of the fused target at the current moment.

3. The method for tracking the high-resolution sensor before the weak and small multiple-target detection, which is claimed in claim 1, is characterized in that the step 6 specifically comprises the following steps:

1) track maintenance and upgrade

(1) For any confirmed track, the fused target state estimation is updated and the confirmed track is output, so that the track is maintained;

(2) for any possible track, updating the possible track according to the fusion target state estimation, and then upgrading the possible track into a confirmed track and outputting the confirmed track;

(3) for any tentative track, updating the tentative track according to the fusion target state estimation, and then upgrading the tentative track into a confirmed track and outputting the confirmed track;

(4) for any flight path head, the fusion target state estimation is associated with the flight path head to form a possible flight path;

2) track degradation and cancellation

(1) Updating the confirmed track according to the predicted value of the confirmed track when any confirmed track of any homologous target is not obtained at the current moment, degrading the confirmed track into a tentative track, and adding the target to the missed detection target set;

(2) canceling any temporary flight path of any 'homologous' target which is not obtained at the current moment;

(3) updating any possible track of any 'homologous' target which is not obtained at the current moment by using the predicted value of the track, and degrading the possible track into a tentative track;

(4) and canceling any flight path head which does not obtain any 'homologous' target at the current moment.

Technical Field

The invention relates to a target detection and tracking method, in particular to a small and weak multi-target detection and tracking method, belongs to the field of information fusion, and is suitable for detecting and tracking a plurality of small and weak targets by a high-resolution sensor.

Background

The high-resolution sensor can provide more target structure information, has extremely wide application background in the aspects of target detection, tracking, identification and the like, and is one of the important development directions of modern sensor technology. However, because the size of the sensor resolution unit is far smaller than the size of the target, the target echo usually occupies a plurality of resolution units, when the signal-to-noise ratio of the target is high, the number of the targets can be corrected by means of target identification, construction of a proper target expansion model and the like, and the target scattering center is estimated to improve the target tracking accuracy; however, when the signal-to-noise ratio of the target is low, the target echo is usually submerged in the noise, and the target measurement data is sometimes not available, so that the target measurement data is difficult to effectively detect by the existing method, and the target cannot be identified and modeled. Therefore, how to realize the effective detection and tracking of a plurality of weak and small targets by a high-resolution sensor is a difficult problem at present.

The track-before-detect (TBD) technology is the most common and effective weak and small detection and tracking method at present, and the method improves the signal-to-noise ratio of a target through long-time accumulation at the cost of time so as to realize effective detection and tracking of the weak and small target. The existing weak and small target detection and tracking method based on the TBD technology is mainly realized by the following steps:

1) storing a plurality of frames of measurement data which are not subjected to threshold processing or lower threshold processing;

2) effectively accumulating the measured data according to the assumed target motion track;

3) and the track of the target is extracted while the existence of the target is declared.

The method for detecting and tracking the weak and small targets based on the TBD technology has two obvious defects: (1) the method treats the target as a 'point target' to be processed, which can cause that one target expanded in a plurality of resolution units is detected into a plurality of targets, thereby causing that the number of the targets is estimated obviously and much, and the algorithm complexity and the calculation are obviously increased; (2) when the target is missed, the particle swarm representing the target in the filter is rapidly degraded, so that the target is easily lost at the subsequent moment.

Disclosure of Invention

The invention aims to provide a method for tracking a small and weak target of a high-resolution sensor before detection, which solves the problems that the number of targets is obviously estimated, the algorithm complexity and the calculation are obviously increased, and the targets are easy to lose at the subsequent moment caused by rapid degradation of a particle swarm representing the targets in a filter when the targets are missed to be detected, and the like, which are caused by taking the targets as point targets by a small and weak target detection and tracking method based on a TBD (tunnel boring detector) technology.

The technical scheme of the method for tracking the small and weak multiple targets of the high-resolution sensor before detection comprises the following steps:

step 1: system initialization

And constructing a main filter based on probability hypothesis density filtering, performing initialization processing on the filter, and constructing a missing detection target set and initializing the missing detection target set into an empty set.

Step 2: sensor measurement acquisition

Acquiring weak and small multi-target measurement data of non-threshold processing of the high-resolution sensor at the current moment, performing A/D conversion, and sending the data to a data processor;

and step 3: missing target assisted search particle set generation

If the missed detection target set is an empty set, directly turning to the step 4; otherwise, firstly, any target in the missed detection target set is predicted in one step to obtain a predicted value of the target state at the current moment, then, the predicted value is taken as a mean value, a target measurement error covariance is taken as a variance, multidimensional normal distribution is constructed, sampling is carried out from the normal distribution to be used for assisting in searching the auxiliary searching particle set of the missed detection target, finally, the auxiliary searching particle sets of all the missed detection targets are added to the main filter, the correction of the main filter is completed, and the missed detection target set is reset to be an empty set.

And 4, step 4: measuring coarse filtering

Filtering the measured data by using the corrected main filter to obtain rough target number and state estimation, wherein the state estimation comprises position and speed estimation of the target;

and 5: "homologous" object partitioning and fusion

Comprehensively utilizing the flight paths of all targets to divide and fuse the rough target state estimation for the homologous targets, and correcting the number of the targets and the target state estimation;

step 6: target track management

Performing track maintaining, upgrading, degrading and canceling operations on the confirmed track, the tentative track, the possible track and the track head, and outputting information of each target track at the current moment;

and 7: and (5) turning to the next moment, and repeating the step (2) to the step (7) until the sensor is turned off.

Specifically, the step 5 specifically includes:

1) performing one-step prediction on each determined track, each tentative track and each possible track existing at the previous moment to obtain a predicted value of each track, establishing an elliptical wave gate according to the prediction covariance, and establishing an annular wave gate according to the target minimum and maximum possible speeds for the track head existing at the previous moment;

2) for any rough target state estimate, if the state estimate is

(1) Defining the state estimation as a track head without any elliptic wave gate or circular wave gate;

(2) if the state estimation only falls into the elliptic wave gate of a certain confirmed track, the state estimation is considered to be originated from the confirmed track, and the state estimation is divided into 'homologous' targets of the confirmed track;

(3) if the state estimation only falls into the elliptic wave gate of a certain tentative track, the state estimation is considered to be originated from the tentative track, and the state estimation is divided into a homologous target of the tentative track;

(4) if the estimated state only falls into the elliptic wave gate of a certain possible track, the estimated state is considered to be originated from the possible track and is divided into the 'homologous' targets of the possible track;

(5) if the state estimation only falls into the ring wave gate of a certain track head, the state estimation is considered to be originated from the track head, and the state estimation is divided into 'homologous' targets of the track head;

(6) if the target falls into a plurality of elliptical wave gates or ring wave gates at the same time, calculating the motion direction of the target according to target speed information contained in the state estimation, and dividing the motion direction into a confirmation track, a temporary track, a possible track or a homologous target of a track head, wherein the included angle between the target course and the motion direction of the target is the minimum;

3) and performing weighted fusion on the homologous targets of each confirmed track, each tentative track, each possible track and each track head by using a probability data interconnection method to obtain the state estimation of the fused target at the current moment.

Specifically, the step 6 specifically includes:

1) track maintenance and upgrade

(1) For any confirmed track, the fused target state estimation is updated and the confirmed track is output, so that the track is maintained;

(2) for any possible track, updating the possible track according to the fusion target state estimation, and then upgrading the possible track into a confirmed track and outputting the confirmed track;

(3) for any tentative track, updating the tentative track according to the fusion target state estimation, and then upgrading the tentative track into a confirmed track and outputting the confirmed track;

(4) for any flight path head, the fusion target state estimation is associated with the flight path head to form a possible flight path;

2) track degradation and cancellation

(1) Updating the confirmed track according to the predicted value of the confirmed track when any confirmed track of any homologous target is not obtained at the current moment, degrading the confirmed track into a tentative track, and adding the target to the missed detection target set;

(2) canceling any temporary flight path of any 'homologous' target which is not obtained at the current moment;

(3) updating any possible track of any 'homologous' target which is not obtained at the current moment by using the predicted value of the track, and degrading the possible track into a tentative track;

(4) and canceling any flight path head which does not obtain any 'homologous' target at the current moment.

Compared with the background art, the beneficial effects of the invention are as follows:

1) the method for tracking the small and weak multiple targets of the high-resolution sensor before detection carries out fusion processing on estimated values from the same target, and solves the problems that the number of the targets is obviously estimated, the algorithm complexity is obviously increased, the calculation is obviously increased and the like caused by processing the targets as point targets in the background technology.

2) According to the invention, by constructing the auxiliary search mechanism of the missed detection target in the main filter, the problem that the particle swarm representing the missed detection in the main filter is rapidly degraded can be effectively prevented, so that the problem that the target is easily lost at the subsequent moment when the missed detection occurs in the target is solved.

Drawings

FIG. 1 is a schematic overall flow chart of the tracking method before the weak and small multiple target detection of the high-resolution sensor.

FIG. 2 is a schematic diagram of the division of the 'homologous' target of the tracking method before the weak and small multiple target detection of the high-resolution sensor.

FIG. 3 is a detection tracking result diagram of the tracking method before the weak and small multiple target detection of the high-resolution sensor.

FIG. 4 is a schematic view of track maintenance and upgrade of the method for tracking a high-resolution sensor before weak and small multi-target detection.

FIG. 5 is a schematic diagram of track degradation and cancellation of the tracking method before weak and small multi-target detection of the high-resolution sensor.

Detailed Description

Without loss of generality, a two-dimensional multi-target tracking scene is assumed, the total simulation time is 80s, and the PHD filter is realized through particle filtering. The sensor is located at the origin of coordinates, the sampling period T is 1s, two-dimensional images in a certain detection area can be provided at each moment, each image comprises m × n 20 × 20 resolution units, and the dimension of each resolution unit is set to be delta_x＝Δ_y1 or so onRepresents the observation data of the time k resolution cell (i, j)

WhereinFor the influence of the target on the intensity of the resolution element (i, j),the measurement noise of the resolution unit (i, j) is assumed to be independent from the resolution unit, and the measurement noise between the previous time and the next time is assumed to be independent from the resolution unit. For simplicity, it is assumed that the measurement noise follows a zero-mean Gaussian distribution, i.e.(x_k,y_k) Location intensity of I_kThe influence of the object of (b) on the resolution cell (i, j) can be approximated by a divergence function as

Sigma is a known parameter and represents the fuzzy spot quantity of the sensor, and the measurement at the time k can be expressed as

The measurement noise variance is set to 3.25, the target signal strength I is set to 20, and the parameter Σ is set to 0.7 according to the snr formula

The targets can randomly appear and disappear in the monitoring area, the appearance positions of the targets accord with uniform distribution in the monitoring area, and the new probability b of the targets_k0.01, the probability of sustained existence of the target e_k0.99, the target motion conforms to the uniform linear motion model

x_k+1＝F(x_k)+w_k

Wherein

w is zero mean Gaussian white noise with a covariance matrix of

Wherein

q₁And q is₂Process noise respectively representing the motion state and intensity of the target, set to q₁＝0.001，q₂＝0.01。

Setting filter parameters: number of particles L representing 1 target₀3000, the number of particles of the new target J is searched_kThe number of particles S of 1 missing inspection object is searched for 4000_kThe preliminary detection threshold γ is 1000, 2.

The tracking method before weak and small multi-target detection of the high-resolution sensor of the invention is described in detail below with reference to the accompanying drawings.

Step 1: initializing the system according to the method in step 1 of the invention content part;

step 2: measuring and acquiring a sensor according to the method in the step 2 of the summary of the invention;

and step 3: generating a missing detection target auxiliary search particle set according to the method in the step 3 of the invention content part;

and 4, step 4: performing coarse measurement filtering according to the method in step 4 of the invention content part;

and 5: dividing and fusing homologous targets according to the method in the step 5 of the invention content part;

step 6: carrying out target track management according to the method in the step 6 of the invention content part;

and 7: and (4) repeating the steps 2 to 7 until the sensor is turned off at the next moment according to the method in the step 7 of the invention content part.

In the embodiment conditions, the tracking method before the weak and small multiple target detection of the high-resolution sensor provided by the invention realizes more accurate estimation of the target number and the target state at each moment (see the attached figure 3) by effectively dividing and fusing the homologous targets (see the step 5) and fusing the estimated values derived from the same target (see the attached figure 2), thereby solving the problems of obvious virtual estimation of the target number, obviously increased algorithm complexity and calculation and the like caused by processing the target as a point target in the background technology; meanwhile, by constructing an auxiliary search mechanism for the missed detection target in the main filter (see steps 3 and 6 and fig. 4 and 5), the particle swarm representing the target in the filter can be effectively prevented from being rapidly degraded, so that the problem that the target is easily lost at the subsequent moment due to the missed detection of the target is solved.