CN101820501A - Stable tracking method of television gate - Google Patents

Abstract

The invention discloses a stable tracking method of a television gate, which belongs to the technical field of television closed-loop tracking of photoelectric telescope. During the space target television closed-loop tracking process of the photoelectric telescope, a tracked object is lost because a non-tracked object passes a gate or because of the shaking of the tracked object. The method of the invention comprises the following steps of: acquiring a velocity vector of the object according to the positions of the tracked object in late three frames and using the velocity vector as a reference for the speed comparison; when a plurality of targets appear in the gate, calculating the velocity vectors of the plurality of targets in two adjacent frames to generate a velocity vector sequence; calculating the difference between the velocity vector sequence and the standard speed and performing modulo arithmetic to obtain a sequence to be estimated; and stably extracting and tracking the tracked object by taking the minimum of an estimation value as the criterion of the tracked object. The television gate stable tracking method has the advantages that: the interference influences on targets are eliminated; and the stable television tracing process is guaranteed by calculating and filtering the velocity vectors of the plurality of objects in the gate.

Description

A kind of method of television gate tenacious tracking

Technical field

The invention belongs to photo-electric telescope TV closed loop tracking technique field, relate in particular to a kind of method of television gate tenacious tracking.

Background technology

The tenacious tracking of photo-electric telescope TV closed loop is widely used in fields such as extraterrestrial target detection, satellite launch site, conventional target range measurement.Because the appearance of jamming target often causes TV to be followed the tracks of and interrupts, and causes track rejection, influences the electrometric effect of overall optical.At present, domestic method in solving TV closed-loop stabilization tracing process adopts least square or Kalman's predictive filtering technology more, and the computation complexity height is difficult to guarantee the extract real-time to target.

Summary of the invention

The method that the purpose of this invention is to provide a kind of television gate tenacious tracking, this method is rejected the influence of jamming target by the multiobject velocity of Bo Mennei is carried out statistical filtering, guarantees the steady of TV tracing process.

To achieve these goals, technical scheme of the present invention is as follows:

Photo-electric telescope is carrying out extraterrestrial target in the TV closed loop tracing process, because non-tracking target is passed through the shake of Bo Men or tracking target itself, causes losing of tracking target.The present invention obtains the velocity of known target according to the position of nearest three frame tracking targets, as speed ratio benchmark; When multiple target appears in Bo Mennei, add up the velocity of adjacent two all targets of interframe, form the velocity sequence; It is poor to do by velocity sequence and reference speed, and asks mould, obtains the sequence of valuation to be evaluated; With the minimum value of assessed value criterion, realize stable extraction and tracking to tracking target as tracking target.

The invention has the beneficial effects as follows: this method is simple, is easy to realize, can guarantee extract real-time and tracking to target.

Description of drawings

Fig. 1 is the pretreatment process figure in the television gate tenacious tracking method of the present invention.

Fig. 2 is the flow chart of television gate tenacious tracking method of the present invention.

Fig. 3 is the design sketch that adopts the tracking target sequence of television gate tenacious tracking method of the present invention.

Embodiment

Below in conjunction with the drawings and specific embodiments the present invention is done description in further detail:

The present invention adopts the VC++6.0 programming, and running environment is Windows XP, and internal memory is greater than 2G, and hard disk is greater than the computer of 80GB.

The flow process of television gate tenacious tracking method of the present invention is as follows:

1) gathers target image and carry out preliminary treatment

As shown in Figure 1, image pick-up card is installed in computer, CCD (Charge Coupled Device) camera acquisition software is installed, start the thread of capture program, the continuous acquisition image of camera, it is as follows to obtain image sequence:

{f(x _i，y _j，t _k)，f(x _i，y _j，t _k+1)，…，f(x _i，y _j，t _k+m-1}(i，j，k＝0，1...N) (1)

Because the figure place of the image that collects is greater than 8, inconvenience is handled, and utilizing following formula is 8 gray level images with image transitions,

$f^{\′}(x_i,y_j,t_k)=\frac{255}{(f_{\max }-f_{\min })}\×(f(x_i,y_j,t_k)-f_{\min }),(i,j,k=\mathrm{0,1}...N)---\left(2\right)$

In the formula, f (x _i, y _j, t _kThe k frame original image of)-collect,

F ' (x _i, y _j, t _kK frame 8 bit images after the)-conversion,

f _Max-k frame original image the maximum gradation value that collects,

f _Min-k frame original image the minimum gradation value that collects.

Gray level image after the conversion is pressed following formula average statistical and variance,

$\mathrm{\μ}=\underset{i=0}{\overset{N}{\mathrm{\Σ}}}\underset{j=0}{\overset{M}{\mathrm{\Σ}}}{f}^{\′}(x_i,y_j,t_k)/(N\×M)---\left(3\right)$

$\mathrm{\σ}=\sqrt{\underset{i=0}{\overset{N}{\mathrm{\Σ}}}\underset{j=0}{\overset{M}{\mathrm{\Σ}}}{(f^{\′}(x_i,y_j,t_k)-u)}^2/(N\×M)}---\left(4\right)$

In the formula, N * M-is the number of pixels of single-frame images.

Because the influence of camera itself and daylight background, the picture noise that collects can be bigger, relatively carries out denoising.Press shown in the step of the 5th among Fig. 1, adopt the method for medium filtering.The basic principle of medium filtering is that the value of any in digital picture or the Serial No. is replaced with the Mesophyticum of each point value in the neighborhood of this point.The major advantage of this processing method is to remove the salt-pepper noise and the isolated noise point of image.

For ease of subsequent treatment, image is carried out binary conversion treatment, the processing procedure of binaryzation: utilize the average of the image that obtains previously and variance to provide a global threshold T (T=μ+3 σ), with f ' (x _i, y _j, t _kThe pixel point value of)＞T is made as 255 (whites), and remaining point all is made as 0 (black), realizes the purpose of binaryzation.White point in the image after the binaryzation is added up, and is 255 if there is gray value, and size thinks then that less than the target of 2 * 2=4 pixel this target is an isolated point, and directly the gray value that will put pays zero.

Obtain the image sequence after the binaryzation, as follows:

{f″(x _i，y _j，t _k)，f″(x _i，y _j，t _k)，...f″(x _i，y _j，t _k)}(i，j，k＝0，1...N) (5)

2) target identification step

Image sequence after the binaryzation that step 1) is obtained carries out logical operation, because the pixel point value in the above-mentioned image sequence is 0 or 255, can represent with 0 or 1.In the satellite target short time that needs to discern is point target, and the fixed star in the image background is a linear target, and the N in the image sequence is got 3, promptly gets continuous three two field pictures and operates, AND-operation is carried out in logically adjacent two two field picture step-by-steps, obtains the image g (x that two width of cloth comprise target _i, y _j, t _k), g (x _i, y _j, t _K+1), as follows:

g(x _i，y _j，t _k)＝f′(x _i，y _j，t _k+1)&f′(x _i，y _j，t _k)

g(x _i，y _j，t _k+1)＝f′(x _i，y _j，t _k+2)&f′(x _i，y _j，t _k+1)

Continuation is to image g (x _i, y _j, t _k), g (x _i, y _j, t _K+1) step-by-step carries out AND-operation, then finally comprised the image of satellite target, and is as follows:

B(x _i，y _j，t _k+1)＝g(x _i，y _j，t _k)&g(x _i，y _j，t _k+1) (6)

The method of above-mentioned target identification is simple, guarantees the real-time of image processing, and antijamming capability is strong.

3) ripple door tenacious tracking step

By continuous three two field pictures identification, the ripple door entangles the target of tracking automatically, just obtained the initial position of target, because non-tracking target (for example: fixed star) pass through the shake of Bo Men or tracking target itself, losing of tracking target will be caused, for guaranteeing ripple door all-the-time stable tracking target, need carry out serial of methods and handle.As shown in Figure 2.

At first, according to target location (the orientation angles A that tentatively identifies _i, luffing angle E _i, corresponding zero-time t _i, the reference speed of calculating target bearing and pitching both direction, wherein i is a frame number:

V _A0＝(A _i+1-A _i)/(t _i+1-t _i)

V _E0＝(E _i+1-E _i)/(t _i+1-t _i)

Secondly, N the target of continuous three frame Bo Mennei traveled through, try to achieve the velocity sequence of both direction, wherein, the speed that per two target locations obtain is:

V _Ak＝(A _k+1-A _k)/(t _i+1-t _i)，V _Ek＝(E _k+1-E _k)/(t _i+1-t _i)，

Wherein, k is a target designation, k=1, and 2 ... N; I is a number of image frames.

Orientation and pitch orientation respectively obtain a velocity sequence, and number equals number of targets N:

M _A1＝[V _A1，V _A2，...V _AN]；M _E1＝[V _E1，V _E2，...V _EN]

Utilize the velocity series value of the both direction that aforementioned calculation obtains and target reference speed relatively, obtain the absolute value of new speed difference, the value of each impact point: V ' _Ak=| V _AK-V _A0|, V ' _Ek=| V _EK-V _E0|

The sequence of the new speed difference absolute value that obtains

M′ _A1＝[V′ _A1，V′ _A2，...V′ _AN]；M′ _E1＝[V′ _E1，V′ _E2，...V′ _EN]

Add up M ' respectively _A1And M ' _E1Minimum value in two sequences obtains the position number [A of two minimum values _i, E _j.].

Position number [the A that statistics obtains _i, E _j.], if i=j confirms that then this sequence number target is a tracking target.

This statistical filtering method based on speed difference, amount of calculation has only 2N time, has guaranteed the real-time of calculating and the accuracy of filtering.

Embodiment:

With certain type bore is that 100mm photo-electric telescope tracking satellite target is an example, the CCD camera is selected the DV887 of Canadian Andor company for use, pixel count is 512 * 512, output gray level is 16, the image sampling time is 20ms, the capture card interface is a pci bus, and orientation and pitch position measuring component are all selected 24 absolute type encoders for use.For implement ripple door tenacious tracking on the said equipment, the condition that also needs to prepare has: to camera focusing, guarantee that extraterrestrial target is at camera target surface epigraph rounding property; Utilize the orbital data guiding device of satellite to point to satellite, guarantee that the initial position of target is in the camera target surface.

Specific implementation process: at first press the workflow among Fig. 1, images acquired, and image carried out preliminary treatment work, detailed method is referring to step 1); After obtaining the image sequence after the binaryzation, set by step 2) method is carried out the target initial identification, obtains the initial position of target on the camera target surface; Carry out ripple door tenacious tracking by the flow process among Fig. 2.Fig. 3 has provided the design sketch of tracking target sequence, in continuous three frame ripple door tracing processs, constantly has other target to enter the ripple door and disturbs extraction to target, and the method by ripple door tenacious tracking of the present invention has realized the continual and steady tracing process to target.

Claims (1)

1. the method for a television gate tenacious tracking is characterized in that, this method comprises the steps:

Extraterrestrial target is carried out in the TV closed loop tracing process at photo-electric telescope, obtain the velocity of known target according to the position of nearest three frame tracking targets, as speed ratio benchmark; When multiple target appears in Bo Mennei, add up the velocity of all targets between adjacent two frames, form the velocity sequence; It is poor to do by velocity sequence and reference speed, and asks mould, obtains the sequence of valuation to be evaluated; With the minimum value of assessed value criterion, realize stable extraction and tracking to tracking target as tracking target.

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