1. A multi-target continuous tracking method for a sector scanning radar is characterized by comprising the following steps:

step (1), for each observation received by the sector scanning radar, selecting the observation which is not utilized by the existing track in the previous scanning period to form a first preselected observation set; establishing a flight path according to the first preselected observation set, filtering by combining the state of the flight path, and calculating the predicted estimation of the flight path in the next scanning period and the corresponding gate time interval;

and (2) for each existing track, iteratively updating the estimate of the track and the corresponding gate time interval in the continuous tracking process in the following mode:

in each scanning period, at the end time of a wave gate time interval corresponding to the current flight path, determining an acquisition time interval according to the wave gate time interval, acquiring the observation in the acquisition time interval, and forming a second preselected observation set; and at the end time of the acquisition time interval, updating the state of the current flight path by using the second preselected observation set, filtering by combining the state of the flight path, and calculating the predicted estimation of the flight path in the next scanning period and the corresponding gate time interval.

2. The fan-scan radar multi-target continuous tracking method according to claim 1,

in step (1), when a flight path is established according to the first preselected observation set, each observation in the first preselected observation set is judged whether the following initialization conditions are met:

wherein z is_x ^reAnd z_y ^reRespectively representing the abscissa and ordinate positions, z, of the observations received at the current moment_x ⁱAnd z_y ⁱRespectively representing the abscissa and ordinate positions, T, of the ith observation in the first preselected observation set_rIs a time difference representing the current time and the time at which the ith observation in the first preselected set of observations was received; v. of_maxRepresenting the target maximum speed, v_errorError representing target velocity calculation;

and if the ith observation in the first preselected observation set meets the initialization condition, initializing the flight path according to the observation at the current moment and the ith observation in the first preselected observation set, and establishing the flight path to obtain the initial state of the flight path.

3. The fan-scan radar multi-target continuous tracking method according to claim 1,

in the step (2), determining the acquisition time interval according to the wave gate time interval, including:

if the wave gate time intervals corresponding to the current flight path and the rest of the existing flight paths are not crossed, the acquisition time interval is the same as the wave gate time interval corresponding to the current flight path;

if the current flight path is crossed with the gate time intervals corresponding to the rest of the existing flight paths, and the latest gate time interval ending time corresponding to the crossed flight path is equal to or earlier than the gate time interval ending time corresponding to the current flight path, the starting time of the earliest gate time interval corresponding to the crossed flight path and the current flight path is the starting time of the acquisition time interval, and the gate time interval ending time corresponding to the current flight path is the acquisition time interval ending time;

if the current flight path is crossed with the gate time intervals corresponding to the rest of the existing flight paths, and the latest gate time interval ending time corresponding to the crossed flight path is later than the gate time interval ending time corresponding to the current flight path, the starting time of the earliest gate time interval corresponding to the crossed flight path and the current flight path is the starting time of the acquisition time interval, and the latest gate time interval ending time corresponding to the crossed flight path is the ending time of the acquisition time interval.

4. The fan-scan radar multi-target continuous tracking method according to claim 1,

in the step (2), calculating the predicted estimate of the flight path in the next scanning period and the corresponding gate time interval, including:

calculating clutter densities corresponding to the observations in the second preselected observation set;

selecting the observation in the second preselected observation set according to the wave gate to obtain an observation set for updating;

calculating a likelihood function of each observation in the second preselected observation set and the current track;

modulating clutter density corresponding to the observation in the observation set for updating by combining a likelihood function;

carrying out data association on the observation set used for updating and the current flight path to obtain the posterior probability of the existence of the target and the data association posterior probability;

updating the track state to obtain a target track state corresponding to the current track;

and calculating the predicted estimation of the flight path in the next scanning period and the corresponding gate time interval.

5. The fan-scan radar multi-target continuous tracking method according to claim 4,

in the step (2), calculating clutter densities corresponding to the observations in the second preselected observation set, including:

looking for an observation z_k(i) With said second preselected observation set Z_τ(k) Of the rest of the observations, and a small distance r of nth between the other observationsⁿ(i) N is an integer greater than 0, z_k(i)∈Z_τ(k) K represents the number of scanning cycles; if the second preselected observation set Z_τ(k) If the number of observations in (b) is less than (n +1), the set of observations received from the beginning of the kth scanning cycle to the current time is assumed to beLooking for an observation z_k(i) In the observation setMiddle nth small distance rⁿ(i)；

Calculating an observation z_k(i) Corresponding sparsity, the expression is:

γ(z_k(i))＝V(rⁿ(i))/n；

wherein the content of the first and second substances,

Γ (·) is the gamma function, l is the dimension of the space;

calculating clutter density according to sparsity, wherein the expression is as follows:

6. the fan-scan radar multi-target continuous tracking method according to claim 5,

in step (2), the second preselected observation set Z is subjected to a wave gate_τ(k) Is selected from the observations inSelecting, including:

for the model σ of the current track τ, the selected observation set y_k(σ) satisfies:

wherein y is an observation set y_k(iii) the observation in (σ) is,representing the predicted observation of the model sigma at the kth update of the current track τ, S_k(σ) an innovation matrix of the model σ at the kth update of the current track τ,is S_k(σ) an inverse matrix, g is the gate size, and the expression is:

chi2inv (·) is chi²Inverse function of the distribution function, P_GRepresenting the gate probability, l represents the dimension of observation y;

for models with different current flight paths tau, all selected observation sets are merged into an observation set for updating

7. The fan-scan radar multi-target continuous tracking method according to claim 6,

in the step (2), calculating a gate time interval corresponding to the track of the next scanning period, including:

calculating the range [ theta ] of the wave gate azimuth angle of each model of the current flight path according to an innovation matrix obtained by calculating the prediction estimation of the flight path in the next scanning period_min,θ_max]；

The expression for the range of the wave gate azimuth angle is:

wherein g is the size of the wave gate, θ₀Is the center azimuth angle of the wave gate, S_ijI, j e to {1,2} is each element of the corresponding innovation matrix of the model;

calculating the wave gate time range of each model of the current flight path according to the range of the wave gate azimuth angle;

and taking the earliest wave gate time interval starting time corresponding to each model as the wave gate time interval starting time of the current track, and taking the latest wave gate time interval ending time corresponding to each model as the wave gate time interval ending time of the current track.

8. The fan-scan radar multi-target continuous tracking method according to claim 7, characterized in that:

according to the range of the wave gate azimuth angle, when calculating the wave gate time range of each model of the current track, setting the time spent by the antenna from the scanning start to the scanning to the azimuth angle as delta T for the azimuth angle theta_sWhen the antenna is in the constant speed scanning area, | theta | < beta-delta, delta T_sThe expression of (a) is:

wherein, ω is₀Alpha is the absolute value of the acceleration of the antenna in the acceleration and deceleration stages, and the azimuth angle range swept by the antenna in the acceleration and deceleration stages isThe scanning range of the antenna is [ -beta, beta [ -beta ]]The scanning direction of the antenna is denoted by f, when f is-1, the antenna scans clockwise, and when f is 1, the antenna scans anticlockwise;

when the antenna is in the acceleration phase, theta is more than beta-delta and f is-1, or theta is less than-beta + delta and f is 1, delta T_sThe expression of (a) is:

when the antenna is in the deceleration phase, theta is more than beta-delta and f is 1, or theta is less than-beta + delta and f is-1, delta T_sThe expression of (a) is:

9. a computer device comprising a memory and a processor, the memory storing a computer program, wherein the processor when executing the computer program implements the steps of the fan-scan radar multi-target continuous tracking method according to any one of claims 1 to 8.

10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the fan-scan radar multi-target continuous tracking method according to any one of claims 1 to 8.

Background

Sector-scan radars scan a surveillance area by changing the direction of the antenna beam by rotating the antenna back and forth over a sector area. After the target is scanned, the antenna returns an observation of the target to the radar, which tracks the target using the received observation. In the sector scanning radar, an antenna continuously transmits observation information of a target in a scanning period, but the observation information is processed only after the scanning period is finished in the conventional tracking method, so that delay exists between tracking and detecting of the target inevitably, and the tracking accuracy is further influenced.

Disclosure of Invention

Technical problem to be solved

The invention aims to solve the technical problem that the low-delay tracking of the sector-scan radar cannot be realized in the prior art.

(II) technical scheme

In order to solve the technical problem, the invention provides a sector scanning radar multi-target continuous tracking method, which comprises the following steps:

step (1), for each observation received by the sector scanning radar, selecting the observation which is not utilized by the existing track in the previous scanning period to form a first preselected observation set; establishing a flight path according to the first preselected observation set, filtering by combining the state of the flight path, and calculating the predicted estimation of the flight path in the next scanning period and the corresponding gate time interval;

and (2) for each existing track, iteratively updating the estimate of the track and the corresponding gate time interval in the continuous tracking process in the following mode:

in each scanning period, at the end time of a wave gate time interval corresponding to the current flight path, determining an acquisition time interval according to the wave gate time interval, acquiring the observation in the acquisition time interval, and forming a second preselected observation set; and at the end time of the acquisition time interval, updating the state of the current flight path by using the second preselected observation set, filtering by combining the state of the flight path, and calculating the predicted estimation of the flight path in the next scanning period and the corresponding gate time interval.

Preferably, in step (1), when a flight path is established according to the first preselected observation set, it is determined whether the following initialization conditions are satisfied for each observation in the first preselected observation set:

wherein z is_x ^reAnd z_y ^reRespectively representing the abscissa and ordinate positions, z, of the observations received at the current moment_x ⁱAnd z_y ⁱRespectively representing the abscissa and ordinate positions, T, of the ith observation in the first preselected observation set_rIs a time difference representing the current time and the time at which the ith observation in the first preselected set of observations was received; v. of_maxRepresenting the target maximum speed, v_errorError representing target velocity calculation;

and if the ith observation in the first preselected observation set meets the initialization condition, initializing the flight path according to the observation at the current moment and the ith observation in the first preselected observation set, and establishing the flight path to obtain the initial state of the flight path.

Preferably, in the step (2), determining the acquisition time interval according to the gate time interval includes:

if the wave gate time intervals corresponding to the current flight path and the rest of the existing flight paths are not crossed, the acquisition time interval is the same as the wave gate time interval corresponding to the current flight path;

if the current flight path is crossed with the gate time intervals corresponding to the rest of the existing flight paths, and the latest gate time interval ending time corresponding to the crossed flight path is equal to or earlier than the gate time interval ending time corresponding to the current flight path, the starting time of the earliest gate time interval corresponding to the crossed flight path and the current flight path is the starting time of the acquisition time interval, and the gate time interval ending time corresponding to the current flight path is the acquisition time interval ending time;

if the current flight path is crossed with the gate time intervals corresponding to the rest of the existing flight paths, and the latest gate time interval ending time corresponding to the crossed flight path is later than the gate time interval ending time corresponding to the current flight path, the starting time of the earliest gate time interval corresponding to the crossed flight path and the current flight path is the starting time of the acquisition time interval, and the latest gate time interval ending time corresponding to the crossed flight path is the ending time of the acquisition time interval.

Preferably, in step (2), calculating the predicted estimate of the flight path in the next scanning period and the corresponding gate time interval includes:

calculating clutter densities corresponding to the observations in the second preselected observation set;

selecting the observation in the second preselected observation set according to the wave gate to obtain an observation set for updating;

calculating a likelihood function of each observation in the second preselected observation set and the current track;

modulating clutter density corresponding to the observation in the observation set for updating by combining a likelihood function;

carrying out data association on the observation set used for updating and the current flight path to obtain the posterior probability of the existence of the target and the data association posterior probability;

updating the track state to obtain a target track state corresponding to the current track;

and calculating the predicted estimation of the flight path in the next scanning period and the corresponding gate time interval.

Preferably, in step (2), calculating a clutter density corresponding to each observation in the second pre-selected observation set comprises:

looking for an observation z_k(i) With said second preselected observation set Z_τ(k) Of the rest of the observations, and a small distance r of nth between the other observationsⁿ(i) N is an integer greater than 0, z_k(i)∈Z_τ(k) K represents the number of scanning cycles; if the second preselected observation set Z_τ(k) If the number of observations in (b) is less than (n +1), the set of observations received from the beginning of the kth scanning cycle to the current time is assumed to beLooking for an observation z_k(i) In the observation setMiddle nth small distance rⁿ(i)；

Computing observationsz_k(i) Corresponding sparsity, the expression is:

γ(z_k(i))＝V(rⁿ(i))/n；

wherein the content of the first and second substances,

Γ (·) is a gamma function,is the dimension of the space;

calculating clutter density according to sparsity, wherein the expression is as follows:

preferably, in step (2), the second preselected observation set Z is subjected to a wave gate_τ(k) The observation of (1) is selected, comprising:

for the model σ of the current track τ, the selected observation set y_k(σ) satisfies:

wherein y is an observation set y_k(iii) the observation in (σ) is,representing the predicted observation of the model sigma at the kth update of the current track τ, S_k(σ) an innovation matrix of the model σ at the kth update of the current track τ,is S_k(σ) an inverse matrix, g is the gate size, and the expression is:

chi2inv (·) is chi²Inverse function of the distribution function, P_GRepresenting the gate probability, l represents the dimension of observation y;

for models with different current flight paths tau, all selected observation sets are merged into an observation set for updating

Preferably, in the step (2), calculating a gate time interval corresponding to a next scanning cycle track includes:

calculating the range [ theta ] of the wave gate azimuth angle of each model of the current flight path according to an innovation matrix obtained by calculating the prediction estimation of the flight path in the next scanning period_min,θ_max]；

The expression for the range of the wave gate azimuth angle is:

wherein g is the size of the wave gate, θ₀Is the center azimuth angle of the wave gate, S_ijI, j e to {1,2} is each element of the corresponding innovation matrix of the model;

calculating the wave gate time range of each model of the current flight path according to the range of the wave gate azimuth angle;

and taking the earliest wave gate time interval starting time corresponding to each model as the wave gate time interval starting time of the current track, and taking the latest wave gate time interval ending time corresponding to each model as the wave gate time interval ending time of the current track.

Preferably, when calculating the gate time range of each model of the current track according to the range of the gate azimuth angle, the time taken by the antenna from the start of scanning to the azimuth angle θ for the azimuth angle θ is set to Δ T_sWhen the antenna is in the constant speed scanning area, | theta | < beta-delta, delta T_sThe expression of (a) is:

wherein, ω is₀Alpha is the absolute value of the acceleration of the antenna in the acceleration and deceleration stages, and the azimuth angle range swept by the antenna in the acceleration and deceleration stages isThe scanning range of the antenna is [ -beta, beta [ -beta ]]The scanning direction of the antenna is denoted by f, when f is-1, the antenna scans clockwise, and when f is 1, the antenna scans anticlockwise;

when the antenna is in the acceleration phase, theta is more than beta-delta and f is-1, or theta is less than-beta + delta and f is 1, delta T_sThe expression of (a) is:

when the antenna is in the deceleration phase, theta is more than beta-delta and f is 1, or theta is less than-beta + delta and f is-1, delta T_sThe expression of (a) is:

the invention also provides computer equipment which comprises a memory and a processor, wherein the memory stores a computer program, and the processor realizes the steps of the fan-scan radar multi-target continuous tracking method when executing the computer program.

The invention also provides a computer readable storage medium, on which a computer program is stored, which when executed by a processor implements the steps of any of the fan-scan radar multi-target continuous tracking methods described above.

(III) advantageous effects

The technical scheme of the invention has the following advantages: the invention provides a multi-target continuous tracking method for a sector-scanning radar, computer equipment and a computer readable storage medium.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic diagram of a fan-scan radar tracking delay;

FIG. 2(a) is a plot of antenna velocity for a sector-scan radar;

FIG. 2(b) is an antenna acceleration curve for a sector-scan radar;

FIG. 3 is a schematic diagram illustrating steps of a multi-target continuous tracking method for a sector-scan radar according to an embodiment of the present invention;

FIG. 4 is a diagram of a target motion trajectory;

FIG. 5(a) is a diagram of IPDA method versus target tracking results of FIG. 4;

FIG. 5(b) is a diagram of a result of tracking the target of FIG. 4 by a sector-scan radar multi-target continuous tracking method according to an embodiment of the present invention;

FIG. 6(a) shows the tracking delay of the IPDA method for target 1;

FIG. 6(b) shows the tracking delay of target 1 by a sector-scan radar multi-target continuous tracking method in the embodiment of the present invention;

FIG. 7(a) shows the tracking delay of the IPDA method for target 2;

FIG. 7(b) shows the tracking delay of target 2 by a sector-scan radar multi-target continuous tracking method in the embodiment of the present invention;

FIG. 8(a) shows the position RMSE of the tracking target 1 by the IPDA method and the multi-target continuous tracking method of the sector-scan radar in the embodiment of the invention;

FIG. 8(b) shows the position RMSE of the tracking target 2 by the IPDA method and the multi-target continuous tracking method of the sector-scan radar in the embodiment of the invention;

FIG. 9(a) shows velocity RMSE of tracking target 1 by IPDA method and a multi-target continuous tracking method of sector-scan radar in the embodiment of the present invention;

fig. 9(b) shows velocity RMSE of tracking target 2 by IPDA method and a method for multi-target continuous tracking by sector radar in the embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer and more complete, the technical solutions in the embodiments of the present invention will be described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention, and based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the scope of the present invention.

As previously described, referring to FIG. 1, tracking is performed using a sector-scan radar if the antenna is at T for target A₁The moment scans it clockwise, and the end moment of the current scanning period is T_end1Delay of tracking_a＝T_end1-T₁(ii) a For target B, if the antenna is at T₂The moment is scanned to it anticlockwise, and the end moment of the current scanning period is T_end2Delay of tracking_b＝T_end2-T₂. It can be seen that the earlier a target is swept in a scan cycle, the greater the tracking delay for that target. In addition, for the same target, the antenna scanning direction is different, and the tracking delay is also different.

To minimize tracking delay, it is preferable to update the state of the track as the antenna sweeps to the end of the gate of the track. The specific implementation method of the scheme relies on the observation selection technology based on the wave gate. In the observation selection technique, the gate is a range of observations that contains, with a probability close to 1, an observation from a target tracked by the current track. Thus, when the antenna is swept across the gate, there is a very small probability that no observation from the target is scanned. Updating at this time achieves a minimum of tracking delay theoretically. The invention researches the shape of the wave gate and uses the geometrical relation to calculate the azimuth angle when the antenna sweeps over the tail end of the wave gate so as to obtain the corresponding time, therefore, the updated time can be determined when the wave gate is built. When the time of the sector scanning radar reaches the corresponding moment of the tail end of the wave gate, the corresponding track is updated, and therefore tracking delay is reduced to the maximum extent. The continuous tracking method provided by the invention can be referred to as an S-CIPDA (sector countinus organized systematic Data association) tracking method for short.

Specific implementations of the above concepts are described below.

The scan period of a sector-scan radar is defined as the time for the radar antenna to scan from one end of the surveillance area to the other. As shown in fig. 2(a) and 2(b), the antenna performs uniform acceleration motion at the beginning of the scanning period, and performs uniform motion after reaching the specified scanning angular velocity. When the scanning period is in a deceleration stage at the end, the antenna performs uniform deceleration movement, and when the speed is zero, the antenna just scans the other end of the monitoring area. The antenna then scans in reverse. In each scanning period, the monitoring area of the radar is divided into an acceleration area, a constant speed area and a deceleration area. Assume that the scanning angle range of the antenna is [ - β, β [ - β [ ]]Beta is the half width of the sector scanned by the antenna, and the scanning angular speed when the antenna scans at a constant speed is omega₀The absolute value of the acceleration during the scanning of the antenna in the acceleration and deceleration stages is alpha, and the azimuth angle range swept by the antenna in the acceleration and deceleration stages is alphaThe scanning period of a single scanning of the antenna is T-2 omega₀/α+2(β-δ)/ω₀. The scanning direction of the antenna is indicated by f, and when f is equal to-1, the antenna is clockwiseWhen f is 1, the antenna scans counterclockwise.

As shown in fig. 3, a method for continuously tracking multiple targets by a sector-scan radar according to an embodiment of the present invention includes:

301, for each observation z received by the fan-scan radar_reTaking the observation z_reObservations acquired during a scan cycle prior to the scan cycle and not utilized by existing tracks form a first preselected observation setSetting a first preselected observation setIncluded are observations ofk represents the number of scanning cycles of the current sector scanning radar for receiving observation, and k is more than or equal to 2;

according to a first preselected observation setAnd establishing a flight path, filtering by combining the state of the flight path, and calculating the predictive estimation of the flight path in the next scanning period (namely the (k +1) th scanning period) and the corresponding gate time interval for updating the flight path next time (namely the (k +1) th time).

In the method provided by the invention, every time an observation is received, the operation of track initialization is carried out, and the track is tried to be established. In order to improve the reliability of the new track, a speed wave gate can be used as a condition for establishing the new track, if the condition is met, the new track is established, and if the condition is not met, the received observation is stored for subsequent use. Obviously, if the first set of preselected observations isFor an empty set, it is considered that no track can be established.

Preferably, in step 301, when a track is created according to the first pre-selected observation set, a velocity wave gate is created with each observation in the first pre-selected observation set as a center, and it is determined whether a new track can be created, that is, for each observation in the first pre-selected observation set, it is determined whether the observation satisfies the following initialization conditions:

wherein z is_x ^reAnd z_y ^reRespectively representing observations z received by the sector-scan radar at the current time_reThe abscissa and ordinate positions of (a), z_x ⁱAnd z_y ⁱRespectively representing a first set of preselected observationsThe abscissa and ordinate positions of the ith observation,T_rto represent the current time and the reception of the first set of preselected observations by the sector sweep radarTime difference of the ith observed time; v. of_maxRepresenting the target maximum speed, v_errorThe error of the target speed calculation can be set according to actual conditions;

if the first preselected observation setIf the ith observation meets the initialization condition, the observation received by the sector scanning radar at the current moment and the first preselected observation set are usedAnd initializing the flight path by the ith observation, and establishing the flight path to obtain the initial state of the flight path.

When a new track is established, according to the current observation z_reCan determine the position of the new track, and then combines the current observation z_reHe-boatThe difference in time stamps between previous observations in the track allows the calculation of the speed of the new track and hence the determination of the initial state of the track. The covariance of the initial state of the track is:

wherein R is_cRepresenting the observed noise covariance matrix observed in a rectangular coordinate system.

Step 302, for each existing track, iteratively updating the estimate of the track and the corresponding gate time interval in the continuous tracking process in the following way:

in each scanning period, at the end time of a gate time interval corresponding to the current track, determining an acquisition time interval according to the gate time interval, and acquiring observations received by a sector scanning radar in the acquisition time interval to form a second preselected observation set;

and at the end time of the acquisition time interval, updating the state of the current flight path by using a second preselected observation set, filtering by combining the state of the flight path, and calculating the predicted estimation of the flight path in the next scanning period and the corresponding gate time interval for updating the flight path next time.

The method of the invention utilizes a second preselected observation set Z during continuous tracking_τ(k) And updating the state of the current track tau, predicting the state of the current track tau in the next scanning period after the updating is finished, and obtaining the estimation of the track tau in the next scanning period so as to realize filtering. By the method, when the time of the sector scanning radar reaches the corresponding moment of the end of the wave gate (namely the end moment of the wave gate time interval), the corresponding track is updated, so that the delay is effectively reduced.

Considering that there may be multiple tracks in the continuous tracking process, and the gates of each track may have intersections, that is, there is an intersection in the corresponding gate time interval, in step 302, to further optimize the time of track update, the determining the acquisition time interval according to the gate time interval includes:

if the current flight path tau and the wave gate time intervals corresponding to the rest of the existing flight paths are not crossed, the acquisition time interval is the same as the wave gate time interval corresponding to the current flight path;

if the current track tau is crossed with the gate time intervals corresponding to the rest of the existing tracks, and the latest gate time interval ending time corresponding to all the tracks crossed with the current track tau is equal to or earlier than the gate time interval ending time corresponding to the current track, the starting time of all the tracks crossed with the current track tau and the earliest gate time interval corresponding to the current track are set as the starting time of the acquisition time interval, and the gate time interval ending time corresponding to the current track is set as the acquisition time interval ending time;

if the current track tau is crossed with the gate time intervals corresponding to the rest of the existing tracks, and the latest gate time interval ending time corresponding to all the tracks crossed with the current track tau is later than the gate time interval ending time corresponding to the current track, the starting time of the earliest gate time interval corresponding to all the tracks crossed with the current track tau and the current track is the starting time of the acquisition time interval, and the latest gate time interval ending time corresponding to all the tracks crossed with the current track tau is the ending time of the acquisition time interval. Where "early" means earlier in time and the corresponding value is smaller, and "late" means later in time and the corresponding value is larger.

Further, when the foregoing manner is implemented, the foregoing manner may be distinguished by determining whether the current track τ is delayed from being updated, if the track τ is not marked as a track delayed from being updated, the track τ is updated according to the end time of the gate time interval corresponding to the track τ, and if the track τ is marked as a track delayed from being updated, the time for updating needs to be adjusted, specifically, step 302 includes:

step 302-1, in the kth scanning period (namely, during the kth updating), in the gate time interval [ t ] corresponding to the current track τ_s(k),t_d(k)]End time t of_d(k) Judging whether the current track tau is marked as a track for postponing updating or not, if so, skipping to execute the step 302-7, otherwise, executing the step 302-2;

step 302-2, judging whether the current track tau is crossed with other tracks by gates, if so, executing step 302-4, otherwise, executing step 302-3;

step 302-3, making the acquisition time interval the same as the gate time interval corresponding to the current track, namely, taking the gate time interval [ t ] of the current track tau_s(k),t_d(k)]Inner observations, constituting a second preselected observation set Z_τ(k)；

Using a second preselected observation set Z_τ(k) Updating and predicting the current track tau, and calculating the updated gate time interval [ t ] of the next scanning period of the current track tau_s(k+1),t_d(k+1)]Adjusting and adjusting a scanning direction parameter f; the scanning direction parameter f is used for adjusting the scanning direction of the sector scanning radar antenna;

step 302-4, if the current track tau is crossed with the wave gates of the rest tracks, but the wave gate end time t of the rest tracks is the latest_{d_max}At the end of the gate time t not later than track tau_d(k) I.e. t_{d_max}≤t_d(k) Then go to step 302-5;

if the current track T is crossed with the rest wave gates, but the latest wave gate end time t of the rest tracks_{d_max}Wave gate end time t later than track tau_d(k) I.e. t_{d_max}＞t_d(k) Then go to step 302-6; t is t_{d_max}The latest wave gate time interval end time corresponding to the current flight path and each flight path crossed with the current flight path is taken as the time;

step 302-5, the starting time of the earliest wave gate time interval corresponding to the crossed flight path and the current flight path is the starting time of the acquisition time interval, the ending time of the wave gate time interval corresponding to the current flight path is the ending time of the acquisition time interval, namely, the time interval [ t ] is taken out_{s_min},t_d(k)]The observations in constitute a second preselected observation set Z_τ(k)，t_{s_min}The current flight path and the earliest starting time of the wave gate time interval corresponding to each flight path crossed with the current flight path;

using a second preselected observation set Z_τ(k) Updating and predicting the current track tau, and calculating the next one of the current track tauGate time interval [ t ] of scanning period update_s(k+1),t_d(k+1)]Adjusting and adjusting a scanning direction parameter f;

step 302-6, let the earliest gate time interval start time corresponding to the crossed track and the current track be the acquisition time interval start time, and the latest gate time interval end time corresponding to the crossed track be the acquisition time interval end time, i.e. t_d(k)'＝t_{d_max}＝max(t_d1,...,t_dn,t_d(k) In which t) is_d1,...,t_dnN number of gate end times, t, crossing the track T_s(k)'＝t_{s_min}＝min(t_s1,...,t_sn,t_s(k) In which t) is_s1,...,t_snN wave gate starting moments crossed with the flight path tau, and the collection time interval is [ t ]_s(k)',t_d(k)']Marking the track tau as a track delayed from updating, and executing the step 302-7;

step 302-7, at the end time t of the acquisition time interval_d(k) ', taking out the time interval [ t ]_s(k)',t_d(k)']Inner observations, constituting a second preselected observation set Z_τ(k)；

Using a second preselected observation set Z_τ(k) Updating and predicting the current track tau, and calculating the updated gate time interval [ t ] of the next scanning period of the current track tau_s(k+1),t_d(k+1)]And adjusting the scanning direction parameter f.

In this preferred embodiment, step 302 may implement the multi-target update procedure through pseudo code as shown in table 1 below:

TABLE 1 Multi-target update Process pseudo code

Preferably, in step 302, calculating the predicted estimate of the flight path of the next scanning period and the corresponding gate time interval includes:

step 302-A, calculating a second preselected observation set Z_τ(k) The clutter density corresponding to each observation.

Further, step 302-A includes:

first, look for observation z_k(i) And a second preselected observation set Z_τ(k) Of the rest of the observations, and a small distance r of nth between the other observationsⁿ(i) N is an integer greater than 0, preferably n is 2, z_k(i)∈Z_τ(k) I has a value from 1 to a second preselected observation set Z_τ(k) K represents the number of scan cycles; if the second preselected observation set Z_τ(k) If the number of observations in (b) is less than (n +1), the set of observations received from the start of the current scanning cycle (i.e., the kth scanning cycle) to the current time is assumed to beLooking for an observation z_k(i) In the observation setMiddle nth small distance rⁿ(i) In order to calculate the clutter density.

Second, the observation z is calculated_k(i) Corresponding sparsity, the expression is:

γ(z_k(i))＝V(rⁿ(i))/n；

wherein the content of the first and second substances,

Γ (·) is a gamma function,is a spatial dimension, preferably

And finally, calculating clutter density according to sparsity, wherein the expression is as follows:

ρ_k(i) representing a second set of preselected observations Z_τ(k) Middle observation z_k(i) Corresponding clutter density, for a second preselected observation set Z_τ(k) Each of which performs the calculation process described above.

Step 302-B, pair the second preselected observation set Z according to the wave gate_τ(k) The observation set used for updating is obtained by selecting the observation in (1).

A track may correspond to multiple motion models, for example, a track may correspond to a constant velocity model, an acceleration model, a turning model, etc., and each model of the track has a corresponding model probability representing the probability of the track conforming to the motion model.

Considering that the model of the flight path may not be unique, it is preferred that the kth update, step 302-B, be based on the gate to the second preselected observation set Z_τ(k) The observation of (1) is selected, comprising:

for the model σ of the current track τ, the selected observation set y_k(σ) satisfies:

wherein y is an observation set y_k(iii) the observation in (σ) is,representing the predicted observation of the model sigma when the current track tau is updated for the kth time, the superscript 'T' representing transposition, S_k(σ) an innovation matrix of the model σ at the kth update of the current track τ,is S_kThe inverse of (a) is then calculated,S_k(σ) belongs to the estimation of the flight path in the k-1 th updating, g is the size of a wave gate, and the expression is as follows:

chi2inv (·) is chi²Inverse function of the distribution function, P_GRepresents the gate probability, l represents the dimension of the observation vector y, which is typically 2;

for models with different current tracks tau, all selected observation sets are combined into one observation set y for updating_kThe expression is:

step 302-C, computing a second preselected observation set Z_τ(k) The likelihood function of each observation with the current track.

Preferably, the second preselected observation set Z_τ(k) Observation z in_k(i) The likelihood function expression of the model sigma of the current track tau is as follows:

wherein z is_k(i)∈V_k(σ) represents observation z_k(i) Selected by the model sigma of the current track tau, V_k(σ) the range of the gates of the model σ representing the current track τ, i having a value from 1 to a second preselected observation set Z_τ(k) N (-) is a probability density function of the gaussian distribution;

obtaining an observation z_k(i) The likelihood function expression with the current track tau is:

wherein, mu_k|k-1(σ) represents the model prediction probability of the model σ at the kth update of the track τ,represents an observation z_k(i) Likelihood function with the model sigma of the current track tau.

Step 302-D, combining likelihood function, for updated observation set y_kObservation y in (1)_k(i) The corresponding clutter density is modulated.

Preferably, step 302-D includes:

calculating the observation y in combination with the likelihood function_k(i) Is the prior probability P of the observation result of the k-th update of the target corresponding to the track tau^τ(i) The expression is:

wherein, theta_k(i) I > 0 denotes observation y_k(i) Is an event derived from object detection, θ_k(0) Event indicating that none of the observations is target detection, Y^k-1Representing the collection of all observations received by the sector scan radar from the initial scan cycle to the k-1 scan cycle,representing the prior probability of the presence of the target at the kth update of the track tau,event, P, indicating the presence of a target corresponding to track τ_DRepresents the discovery probability, P, of the sector-scan radar to the target_GRepresents the wave gate probability, m_kRepresenting observation set y for updating_kI is from 1 to m_k；

Obtain an observation y for track τ_k(i) The corresponding clutter density after modulation is:

and the flight path eta is the rest existing flight paths except the current flight path tau.

If y_k(i) If the clutter density is not selected by other tracks, the corresponding clutter density is not changed.

Step 302-E, Observation set y to be used for updating_kCarrying out data association with the current track tau to obtain the posterior probability of the existence of the targetAnd data associated posterior probabilityY^kRepresenting the collection of all observations received by the sector scan radar from the initial scan cycle to the kth scan cycle.

Preferably, step 302-E comprises:

calculate the kth update, observe y_k(i) Likelihood ratio of_kThe expression is:

obtaining the posterior probability of the existence of the target after the kth update of the track tauThe expression is as follows:

wherein the content of the first and second substances,representing the prior probability of the existence of the target when the kth time of the track tau is updated;

the obtained data association posterior probability expression is as follows:

and step 302-F, updating the track state to obtain a target track state corresponding to the current track tau.

Preferably, step 302-F includes:

first calculate a given ith observation y_k(i) The posterior model probability of (2) is expressed as:

wherein, mu_k|k-1(σ) a model prediction probability representing the model σ at the kth update of the track τ;

then, calculating model probabilities of the models of the current track tau, wherein the expression is as follows:

then calculating the posterior data association probability, wherein the expression is as follows:

wherein, beta_k(i) The posterior probability of the data association is represented,represents an observation z_k(i) A likelihood function of the model sigma with the current track tau,represents an observation z_k(i) And the likelihood function of the current track tau.

Calculating a given observation y_k(i) The state estimation value and covariance of each model of the current track tau are expressed as follows:

wherein the content of the first and second substances,representing a given observation y_k(i) State estimate of time-current track tau model sigma, P_k|k(i, σ) denotes a given observation y_k(i) The state covariance of the current track tau model sigma,representing the predicted value of the state of the model sigma at the kth update of the track tau, P_k|k-1(σ) represents the predicted covariance of the model σ at the kth update of the track τ,representing a Kalman filtering estimation, H representing an observation matrix, and R representing an observation noise covariance matrix.

Obtaining a target track state expression corresponding to the current track tau as follows:

wherein the content of the first and second substances,represents the kth updated track state of track tau, P_k|kRepresents the flight path state covariance after the kth update of the flight path tau.

And step 302-G, calculating the predicted estimation of the flight path in the next scanning period and the corresponding gate time interval.

Preferably, in step 302-G, the state prediction, the predicted observation, the prior probability of the presence of the target and the track gate time of each model of the track when updated next are calculated, specifically:

assuming that the total number of M models is M, the mean value of the track state corresponding to the sigma-th model isTrack state covariance of P_k|k(σ)。

Firstly, calculating the model prediction probability of each model, wherein the expression is as follows:

wherein, gamma is_σmDenotes the probability, μ, of the target switching to the m-th model at the k + 1-th update under the condition that the k-th update follows the a-th model_k+1|k(m) represents the model prediction probability.

And then solving the probability and the mixing state of the mixing model, wherein the expression is as follows:

wherein the content of the first and second substances,the prior probability that the k-th update is the sigma model under the condition that the k + 1-th update is the m model, is called the mixed model probability for short,representing the state of the hybrid model of the model m,represents the hybrid model state covariance of model m.

For model m, the expression for the state prediction is:

wherein the content of the first and second substances,representing the predicted value of the state of the model m at the k +1 th update of the flight path tau, P_k+1|k(m) represents the predicted covariance matrix of model m at the k +1 th update of track τ. F denotes a state transition matrix, F^TQ represents the process noise matrix as a transpose of F.

The predicted observation expression is obtained as:

S_k(m)＝HP_k+1|k(m)H^T+Q；

wherein the content of the first and second substances,represents the predicted observation of the model m at the k +1 th update of the current track, S_k(m) represents the innovation matrix of model m at the kth update of the current track.

The prior probability expression of the existence of the target is as follows:

wherein the content of the first and second substances,the prior probability of the existence of the target when the track tau is updated for the k +1 th time is represented, and gamma is the conversion probability of the existence of the target and can be set according to the actual situation.

Preferably, in step 302, calculating a gate time interval corresponding to a track of a next scanning period includes:

according to an innovation matrix S obtained by calculating the prediction estimation of the flight path of the next scanning period_k(m) calculating the range [ theta ] of the azimuth angle of the wave gate for the model m of the current track_min,θ_max]；

Further, the expression for the range of the wave gate azimuth angle is:

wherein g is the size of the wave gate, θ₀For predicted observation of the centre azimuth of the wave gate, i.e. corresponding to model mAzimuth angle of (S)_ijI, j e {1,2} is the corresponding innovation matrix S of model m_k(m) each element; correspondingly calculating the range of the wave gate azimuth angle for each model of the current track by adopting the mode;

calculating the wave gate time range of each model of the current track according to the wave gate azimuth angle range, for example, the wave gate time range of the model m is

Taking the earliest wave gate time interval starting time corresponding to each model as the wave gate time interval starting time of the current track, and taking the latest wave gate time interval ending time corresponding to each model as the wave gate time interval ending time of the current track, namely, for the kth scanning period, the flight pathStarting time t of wave gate time interval of trace tau_s(k)＝min{t_s ¹，...，t_s ^M}，The end time of the wave gate time interval is t_d(k)＝max{t_d ¹，...，t_d ^M}，

In step 301, a flight path is established according to the first preselected observation set, filtering is performed in combination with the state of the flight path, and a prediction estimation of the flight path in the next scanning period and a corresponding gate time interval are calculated.

Preferably, when calculating the gate time range of each model of the current track according to the range of the gate azimuth angle, the time taken by the antenna from the start of scanning to the azimuth angle θ for the azimuth angle θ is set to Δ T_sWhen the antenna is in the constant speed scanning area, | theta | < beta-delta, delta T_sThe expression of (a) is:

wherein, ω is₀Alpha is the absolute value of the acceleration of the antenna in the acceleration and deceleration stages, and the azimuth angle range swept by the antenna in the acceleration and deceleration stages isThe scanning range of the antenna is [ -beta, beta [ -beta ]]The scanning direction of the antenna is denoted by f, when f is-1, the antenna scans clockwise, and when f is 1, the antenna scans anticlockwise;

when the antenna is in the acceleration phase, theta is more than beta-delta and f is-1, or theta is less than-beta + delta and f is 1, delta T_sThe expression of (a) is:

when the antenna is in the deceleration phase, theta is more than beta-delta and f is 1, or theta is less than-beta + delta and f is-1, delta T_sThe expression of (a) is:

please refer to fig. 4 to 9(b), the present invention also performs simulation verification on the proposed multi-target continuous tracking method for the fan-scan radar, which is located at the origin (0m, 0m) of the cartesian coordinate system. Two targets are subjected to the motion process of uniform velocity-uniform acceleration-uniform velocity-turning-uniform velocity, the initial states of the two targets (namely target 1 and target 2) are shown in table 2, x represents the abscissa of the target position,representing the velocity of the target on the abscissa,representing the acceleration of the target on the abscissa, y represents the ordinate of the target position,representing the velocity of the object on the ordinate,representing the acceleration of the object on the ordinate.

TABLE 2 initial states of two targets

The accelerations of the two target acceleration phases are respectively [ -0.2m/s ]²,0.1m/s²]And [0.2m/s²,0.1m/s²]. In the turning stage, the angular speeds are pi/30, and 100 Monte Carlo simulations are carried outEach simulation simulates 70 update processes. Clutter density in the surveillance area is 1.0 × 10^-7/scan/m²And the clutter is uniformly distributed. The half width of a sector scanned by the radar antenna is beta-pi/3, the scanning speed in constant-speed scanning is (pi/6) rad/s, and the angular acceleration is (pi/3) rad/s². From these data, the azimuth angle range of the acceleration and deceleration area is δ ═ pi/24, and the single scan period is T ═ 4.5 s. The process noise of the target motion is set to ds 0.01m/s²The standard deviation of the observation noise of the distance and the azimuth angle is respectively sigma_r＝5m，σ_θ＝0.01deg。

The motion trajectories of the two targets are obtained as shown in fig. 4, the IPDA method (i.e., the conventional probabilistic interconnection method) is used for comparing the present invention, as shown in fig. 5(a) to fig. 9(b), and it can be seen from fig. 5(a) and fig. 5(b) that the IPDA method and the S-CIPDA method of the present invention both successfully track the target, but it can be seen from fig. 6(a) to fig. 7(b) that the tracking delay of the S-CIPDA method is much lower than that of the IPDA method, the tracking delay of the IPDA method to the target is related to the target position and the scanning direction, and the tracking delay fluctuates with updating, and it can be seen from fig. 8(a) to fig. 9(b) that the tracking accuracy of the IPDA method and the S-CIPDA method of the present invention is very close in most of time, and sometimes the tracking accuracy of the IPDA method is lower than that of the S-CIPDA method. The multi-target continuous tracking method for the sector-scan radar greatly reduces tracking delay, and the tracking accuracy is not reduced due to the reduction of the tracking delay.

In particular, in some preferred embodiments of the present invention, there is further provided a computer device, including a memory and a processor, where the memory stores a computer program, and the processor implements the steps of the multi-target continuous tracking method for the sector sweep radar in any one of the above embodiments when executing the computer program.

In other preferred embodiments of the present invention, a computer-readable storage medium is further provided, on which a computer program is stored, and the computer program is executed by a processor to implement the steps of the fan-scan radar multi-target continuous tracking method in any one of the above embodiments.

It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above may be implemented by a computer program, which may be stored in a non-volatile computer-readable storage medium, and when executed, the computer program may include the processes of the embodiments of the sector-scan radar multi-target continuous tracking method described above, and will not be described again here.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.