CN101644762B - Image-locating method of synthetic aperture sonar and system - Google Patents

Abstract

The invention provides an image-locating method of synthetic aperture sonar and a system. The method comprises the following steps: mounting a launching site at the front end of a towed body of the system for launching a single-frequency signal or a linear frequency modulated signal; respectively mounting receiving energy transducers in the same depth at both sides of a towboat to receive signals emitted by the launching site on the towed body and respectively calculate the distances of the receiving energy transducers at both sides from the towed body according to the received signals; fitting a towboat track close to a straight line according to the position of the towboat to deduce a distance and an azimuth angle of the towed body from the position of the towboat; deducing the position of the towed body according to the distance, the azimuth angle and the GPS position of the towboat; and calculating the position of each pixel in an image according to the position of the towed body, a height to bottom measured by an ADL on the towed body and a synthetic aperture length. The invention can accurately position the sonar image by adding two receiving energy transducers and one launching site to the prior system, thereby being simple and practical and solving the problem that the synthetic aperture sonar is hard to position.

Description

A kind of image position method of synthetic aperture sonar and system

Technical field

The invention belongs to the synthetic aperture sonar signal process field, relate generally to image position method and system in the synthetic aperture sonar system.

Background technology

The synthetic aperture imaging sonar is a kind of acoustics imaging device; It shines testees with an acoustics " antenna " at a plurality of position emission sound waves; And receive the sound wave reflect; Form virtual big " antenna " through method for processing signals, be higher than the imaging effect when using " antenna " far away thereby can obtain resolution.It is mainly used in seabed mapping, operations such as object salvaging.Its main system formation and working method are as shown in Figure 1; Towed body drags towboat roughly along straight ahead; A transmitting transducer and a receiving transducer array (or claiming to receive battle array) are installed on the towed body; Installation sound Doppler log (ADL) also on the towed body simultaneously, be used for measuring speed and towed body the end of apart from height etc.Dry end signal processor and GPS (GPS) are installed on the towboat, and all signals of green end are transferred to the dry end signal processor through towing cable, carry out imaging processing.Emission battle array on the towed body transmits at some discontinuous bearing points, receives battle array simultaneously and receives, and the coherence stack of the image of the low resolution that obtains through each bearing point obtains final high-resolution image.

Existing synthetic aperture sonar system does not consider the soft connection (connecting with towing cable between towed body and the towboat) between towed body and the towboat; Just roughly infer the position that towed body according to the GPS position of towboat; And then image positioned, so out of true, have very big error sometimes.

Summary of the invention

In order to address the above problem, the object of the present invention is to provide a kind of image position method and system of synthetic aperture sonar, this system can accurately locate sonar image, solves the difficult problem in synthetic aperture sonar location.

To achieve these goals, the present invention takes following technical scheme:

In the image position method of synthetic aperture sonar of the present invention; The position of the same degree of depth respectively increases a receiving transducer respectively in said towboat both sides, and at the front end of said towed body an emission battle array is installed, and utilizes this to be installed in two receiving transducers of towboat left and right sides; With an emission battle array that is installed on the towed body; Make its synchronous clock that sends through the electronic system in the towed body carry out synchronous working, the signal through the signal and the emission paroxysm of receiving transducer reception are penetrated calculates; According to the gps data on the towboat, obtain locations of pixels in the image then.Concrete steps are following:

101) at the front end of towed body the emission battle array is installed, is used to launch simple signal or linear FM signal.

102) receiving transducer is installed in the place of the same degree of depth in said towboat both sides, receives the signal that the said emission paroxysm on the above-mentioned towed body is penetrated.

103) the dry end signal processor on the towboat is according to step 102) signal received calculates the receiving transducer that the is positioned at both sides distance apart from towed body respectively.

The position of 104) passing by according to towboat simulates a towboat flight path near straight line.

105) obtain the distance and bearing angle of towed body apart from this position of towboat.

106) according to towed body apart from the distance and bearing angle of this position of towboat and the GPS position of towboat, the position that draws towed body.

107) position that the height end of apart from that records according to sound Doppler log ADL on the position of towed body, the towed body and length of synthetic aperture calculate each pixel in the image.

In addition, the framing system of synthetic aperture sonar of the present invention comprises: towed body, towboat, be installed on the towed body sound Doppler log, be installed on GPS, dry end signal processor, the transmitting transducer that is installed on the towed body side and receiving transducer array on the towboat; It is characterized in that the position of the same degree of depth respectively increases receiving transducer of installation respectively in the said towboat left and right sides, and an emission battle array is installed again at the front end of said towed body; Utilize this to be installed in two receiving transducers of towboat left and right sides; With a said emission battle array that is installed on the towed body, make its synchronous clock that sends through the electronic system in the said towed body carry out synchronous working, the signal that signal that receives through the said receiving transducer that is installed in the towboat left and right sides and said emission paroxysm are penetrated; Calculate; According to the gps data on the towboat, obtain locations of pixels in the image, wherein then; The said emission of installing at the front end of said towed body gust; Be used to launch simple signal or linear FM signal, the said receiving transducer that install the position of the same degree of depth in said towboat both sides receives the signal that the said emission paroxysm on the above-mentioned towed body is penetrated; Said dry end signal processor calculates the said receiving transducer that the is positioned at both sides distance apart from towed body respectively according to the signal of receiving; And, simulate a towboat flight path near straight line according to the position that the towboat that GPS is confirmed is passed by, obtain the distance and bearing angle of towed body apart from this position of towboat; Then; By the distance and bearing angle of the above-mentioned towed body that draws apart from the towboat current location, and the position of the current towboat that records of GPS, utilize said dry end signal processor to calculate the position of towed body; At last, the height that records according to sound Doppler log on the position of towed body, the towed body of said dry end signal processor and the length of synthetic aperture position that calculates each pixel in the image end of apart from.

Image position method and system according to synthetic aperture sonar of the present invention; Only need in the synthetic aperture sonar system, to increase two receiving transducers and an emission battle array; Just can accurately locate sonar image, not only simple and practical but also solved the difficult problem in synthetic aperture sonar location.

Description of drawings

Fig. 1 is that the main system of existing synthetic aperture sonar constitutes and the working method synoptic diagram.

Fig. 2 is that the portion that wants of the framing system of synthetic aperture sonar of the present invention constitutes synoptic diagram.

Fig. 3 is the process flow diagram that utilizes the image position method of synthetic aperture sonar of the present invention.

Fig. 4 is that the position of an embodiment of image position method of synthetic aperture sonar of the present invention concerns synoptic diagram.

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is done further explain.

Fig. 1 is that the main system of synthetic aperture sonar constitutes and the working method synoptic diagram.As shown in Figure 1; A transmitting transducer and a receiving transducer array (or claiming to receive battle array) are installed in the towed body side; The inner installation sound of towed body Doppler log ADL electronic systems such as (measuring speed and towed body be height the end of apart from) is installed dry end signal processor and GPS on the towboat simultaneously, and towboat drags towed body roughly along straight ahead through towing cable; All signals of green end are transferred to the dry end signal processor through towing cable, carry out imaging processing.

Fig. 2 is that the portion that wants of the framing system of synthetic aperture sonar of the present invention constitutes synoptic diagram.System according to the invention has increased an emission battle array and each increases a receiving transducer is installed respectively the position of the same degree of depth in the towboat left and right sides at the front end of towed body on the basis of original synthetic aperture sonar system; Utilize this to be installed in two receiving transducers of towboat left and right sides; With an emission battle array that is installed on the towed body, make its synchronous clock that sends through the electronic system in the towed body carry out synchronous working, the signal that signal that receives through receiving transducer and emission paroxysm are penetrated; Calculate; According to the gps data on the towboat, obtain locations of pixels in the image then, thereby realize the location.The a position of the receiving transducer a that increases shown in Fig. 2 in Fig. 1.

Fig. 3 is the process flow diagram that utilizes the image position method of synthetic aperture sonar of the present invention, introduces image position method of the present invention in detail according to the process flow diagram of Fig. 3 below.

In step 101) in, at the front end of towed body the emission battle array is installed, be used to launch simple signal or linear FM signal.

In step 102) in, receiving transducer is installed in the position of the same degree of depth in the towboat both sides, and the synchronizing signal according to control emission paroxysm on the towed body is penetrated receives.

In step 103) in, establish step 101) transmitting of emission battle array be s (t), step 102) receiving transducer of towboat both sides is fixed on the position of same depth, the degree of depth is Dr, the b position on a position and corresponding opposite among Fig. 1, and the distance between 2 can measure, and is L _r, the signal that the both sides receiving transducer receives is respectively

r _a(t)＝s(t-τ _a)+w _a(t)

r _b(t)＝s(t-τ _b)+w _b(t)

Dry end signal processor on the towboat carries out relevant treatment to the reception signal of both sides with transmitting, and seeks the peak of related function, thereby obtains τ _a, τ _b

Towed body apart from the distance of towboat both sides is:

R _a＝C*τ _a

R _b=C* τ _b(C is the velocity of sound)

In step 104) in, one section position that towboat was walked of dry end signal processor record, for (Lon1, and Lan1) (Lon2, Lan2) ... (LonN, LanN).

Can obtain the position angle of match flight path straight line

${\mathrm{\θ}}_{\mathrm{line}}=\mathrm{arctg}(\frac{1}{N-1}\underset{n=2}{\overset{N}{\mathrm{\Σ}}}({\mathrm{Lan}}_n-{\mathrm{Lan}}_n)/({\mathrm{Lon}}_{n-1}-{\mathrm{Lon}}_{n-1}))$

In step 105) in, as shown in Figure 4, be that the position of an embodiment of image position method of synthetic aperture sonar of the present invention concerns synoptic diagram.A, b are two receiving transducers, a, and 2 mid point c of b are towboat projection vertically downward.T is towed body projection vertically upward.The towed body underwater penetration can be recorded by ADL, is D _t, towboat apart from the distance of towed body projection at grade is:

$L=\sqrt{\frac{{{2R}_a}^2+{{2R}_b}^2-{L_r}^2}{4}}$

Towed body is to 2 straight lines of towboat and towboat flight path included angle of straight line θ ₀For:

${\mathrm{\θ}}_0=\arcsin \left(\frac{{\left(\frac{L_r}{2}\right)}^2+L^2-{R_a}^2}{2\·\frac{L_r}{2}\·L}\right)$

By Fig. 4, towboat to the position angle of towed body line is:

θ＝θ _line-θ ₀

In step 106) in, as shown in Figure 4, dotted line 1 is the towboat flight path of match.According to the longitude and latitude of towboat, and the position angle and the distance of towboat and towed body line, calculate (normal solution) formula by landlord's key to exercises, calculate the current longitude and latitude (Lon of towed body _Towfish, Lan _Towfish).Calculation procedure is following:

$A=\sqrt{1+e^{\′2}{\cos }^4\left(\mathrm{Lan}1\right)}$

$B=\sqrt{1+e^{\′2}{\cos }^2\left(\mathrm{Lan}1\right)}$

$C=\sqrt{1+e^{\′2}}$

σ＝LB ²/(aC)

Lon _towfish＝Lon1+1/Aarctg[(Atgσsinθ)/(Bcos(Lan1)-tgσsin(Lan1)cosθ)]

ω＝A(Lon _towfish-Lon1)/2

D＝1/2arcsin[sinσ(cosθ-1/Asin(Lan1)sinθtgω)]

Lan _towfish＝Lan1+2D[B-3/2e′ ²Dsin(2Lan1+4/3BD)]

In the formula, e ' be second eccentric ratio e ' ²=(a ²-b ²)/b ²=0.007, a is semimajor axis of ellipsoid (about 6377.4km), (Lon1 Lan1) is the longitude and latitude of current towboat, and L, θ are respectively the relative towboat distance of towed body, and the orientation (positive north, clockwise).

In step 107) in, for impact point as shown in fig. 1, the coordinate of target in the image block of current bearing point output be (x y), calculates impact point and to the oblique distance of towed body is:

R＝y*(d/2)

D is for receiving a battle array diameter, d/2 be image orientation to distance to resolution,

Half length of synthetic aperture is:

(λ is a wave length of sound, and d is for receiving the array element diameter)

Thereby settle accounts out among Fig. 1 impact point perpendicular to the distance R of towed body course-and-bearing to the towed body course line ₁For:

(H is that towed body is apart from bottom height)

Impact point is parallel to the distance R of the direction in towed body course line apart from towed body ₂For:

R ₂＝D _half+x·(d/2)

By towed body longitude and latitude, R ₁And R ₂, calculate (normal solution) formula according to landlord's key to exercises, at first can obtain and be parallel to the towed body course-and-bearing apart from towed body R ₁Longitude and latitude (the Lon of the point at place _Temp, Lan _Temp), calculation procedure is following:

$A=\sqrt{1+e^{\′2}{\cos }^4\left({\mathrm{Lan}}_{\mathrm{towfish}}\right)}$

$B=\sqrt{1+e^{\′2}{\cos }^2\left({\mathrm{Lan}}_{\mathrm{towfish}}\right)}$

$C=\sqrt{1+e^{\′2}}$

σ＝R ₂B ²/(aC)

Lon _temp＝Lon _towfish+1/Aarctg[(Atgσsinθ _line)/(Bcos(Lan _towfish)-tgσsin(Lan _towfish)cosθ _line)]

ω＝A(Lon _temp-Lon _towfish)/2

D＝1/2arcsin[sinσ(cosθ-1/Asin(Lan _towfish)sinθ _linetgω)]

Lan _temp＝Lan _towfish+2D[B-3/2e′ ²Dsin(2Lan _towfish+4/3BD)]

And then can calculate the longitude and latitude (Lon of this target _Point, Lan _Point), calculation procedure is following:

$A=\sqrt{1+e^{\′2}{\cos }^4\left({\mathrm{Lan}}_{\mathrm{temp}}\right)}$

$B=\sqrt{1+e^{\′2}{\cos }^2\left({\mathrm{Lan}}_{\mathrm{temp}}\right)}$

$C=\sqrt{1+e^{\′2}}$

σ＝R ₁B ²/(aC)

Lon _point＝Lon _temp+1/Aarctg[(Atgσsin(θ _line±90)/(Bcos(Lan _temp)-tgσsin(Lan _temp)cos(θ _line±90)]

ω＝A(Lon _point-Lon _temp)/2

D＝1/2arcsin[sinσ(cos(θ _line+90)-1/Asin(Lan _temp)sin(θ _line±90)tgω]

Lan _point＝Lan _temp+2D[B-3/2e′ ²Dsin(2Lan _temp+4/3BD)]

In above-mentioned steps, θ _LineIn ± 90 calculating,, use θ for the left-side images of synthetic aperture sonar _Line+ 90, for the image right of synthetic aperture sonar, use θ _Line-90.

Claims (3)

1. the image position method of a synthetic aperture sonar is used for the image of synthetic aperture sonar is positioned, and this method comprises the steps:

101) at the front end of towed body the emission battle array is installed, is used to launch simple signal or linear FM signal;

102) receiving transducer is installed in the position of the same degree of depth in the towboat both sides, receives the signal that the said emission paroxysm on the above-mentioned towed body is penetrated;

103) the dry end signal processor on the towboat is according to step 102) signal received calculates the receiving transducer that the is positioned at both sides distance apart from towed body respectively;

The position of 104) passing by according to towboat simulates a towboat flight path near straight line;

105) obtain the distance and bearing angle of towed body apart from this position of towboat;

106) according to towed body apart from the distance and bearing angle of this position of towboat and the GPS position of towboat, the position that draws towed body;

107) position that the height end of apart from that records according to sound Doppler log on the position of towed body, the towed body and length of synthetic aperture calculate each pixel in the image.

2. the image position method of synthetic aperture sonar as claimed in claim 1; It is characterized in that; Said step 103) in; If set said step 101) in transmitting of emission battle array be s (t), said step 102) in be fixed on the receiving transducer of same depth position, towboat both sides the degree of depth be Dr, the distance between the receiving transducer of these both sides is L _r, then the receiving transducer signal that receives in both sides is respectively:

r _a(t)＝s(t-τ _a)+w _a(t)

r _b(t)＝s(t-τ _b)+w _b(t)

Dry end signal processor on the towboat carries out relevant treatment to the reception signal of both sides with transmitting, and seeks the peak of related function, thereby obtains τ _a, τ _b,

Towed body apart from the distance of towboat both sides is:

R _a＝C*τ _a

R _b＝C*τ _b

Wherein, C is the velocity of sound;

Said step 104) in, one section position that towboat was walked of said dry end signal processor record, for (Lon1, and Lan1) (Lon2, Lan2) ... (LonN, LanN), wherein (Lon1 Lan1) is current towboat position, and thus, the position angle of obtaining match flight path straight line is:

${\mathrm{\θ}}_{\mathrm{line}}=\mathrm{arctg}(\frac{1}{N-1}\underset{n=2}{\overset{N}{\mathrm{\Σ}}}({\mathrm{Lan}}_n-{\mathrm{Lan}}_n)/({\mathrm{Lon}}_{n-1}-{\mathrm{Lon}}_{n-1}))$

Said step 105) in, if the position of two receiving transducers is respectively a, b, the towboat mid point c that is projected as 2 a, b vertically downward, towed body vertically upward be projected as t, the towed body underwater penetration is measured as D by Doppler log _t, then towboat apart from the distance of towed body projection at grade is:

$L=\sqrt{\frac{{{2R}_a}^2+{{2R}_b}^2-{L_r}^2}{4}}$

Towed body is to 2 straight lines of towboat and towboat flight path included angle of straight line θ ₀For:

${\mathrm{\θ}}_0=\arcsin \left(\frac{{\left(\frac{L_r}{2}\right)}^2+L^2-{R_a}^2}{2\·\frac{L_r}{2}\·L}\right)$

Towboat to the position angle of towed body line is:

θ＝θ _line-θ ₀

Said step 106) in, (Lon1 Lan1), and the azimuth angle theta and the distance L of towboat and towed body line, calculates formula by landlord's key to exercises, calculates the current longitude and latitude (Lon of towed body according to the current longitude and latitude of towboat _Towfish, Lan _Towfish), calculation procedure is following:

$A=\sqrt{1+e^{\′2}{\cos }^4\left(\mathrm{Lan}1\right)}$

$B=\sqrt{1+e^{\′2}{\cos }^2\left(\mathrm{Lan}1\right)}$

$C=\sqrt{1+e^{\′2}}$

σ＝LB ²/(aC)

Lon _towfish＝Lon1+1/Aarctg[(Atgσsinθ)/(Bcos(Lan1)-tgσsin(Lan1)cosθ)]

ω＝A(Lon _towfish-Lon1)/2

D＝1/2arcsin[sinσ(cosθ-1/Asin(Lan1)sinθtgω)]

Lan _towfish＝Lan1+2D[B-3/2e′2Dsin(2Lan1+4/3BD)]

In the formula, e ' is second excentricity, e ' ²=(a ²-b ²)/b ²=0.007, a is a semimajor axis of ellipsoid, (Lon1 Lan1) is the longitude and latitude of current towboat, and L, θ are respectively the relative towboat distance and bearing of towed body,

In said step 107) in, if the coordinate of target setting in the image block of current bearing point output be (x y), then calculates impact point and to the oblique distance of towed body is:

R＝y*(d/2)

Wherein, d is for receiving a battle array diameter, d/2 be image orientation to distance to resolution,

Half length of synthetic aperture is:

$D_{\mathrm{half}}=\frac{0.88*\mathrm{\λ}/d}{2}\·R$

λ is a wave length of sound, and d is reception array element diameter,

Thereby settle accounts out impact point perpendicular to the distance R of towed body course-and-bearing to the towed body course line ₁For:

$R_1=\sqrt{R^2-H^2}$

Wherein, in the formula H be towed body apart from bottom height,

Impact point is parallel to the distance R of the direction in towed body course line apart from towed body ₂For:

R ₂＝D _half+x·(d/2)

By towed body longitude and latitude, R ₁And R ₂, calculate formula according to landlord's key to exercises, at first can obtain and be parallel to the towed body course-and-bearing apart from towed body R ₁Longitude and latitude (the Lon of the point at place _Temp, Lan _Temp), calculation procedure is following:

$A=\sqrt{1+e^{\′2}{\cos }^4\left({\mathrm{Lan}}_{\mathrm{towfish}}\right)}$

$B=\sqrt{1+e^{\′2}{\cos }^2\left({\mathrm{Lan}}_{\mathrm{towfish}}\right)}$

$C=\sqrt{1+e^{\′2}}$

σ＝R ₂B ²/(aC)

Lon _temp＝Lon _towfish+1/Aarctg[(Atgσsinθ _line)/(Bcos(Lan _towfish)-tgσsin(Lan _towfish)cosθ _line)]

ω＝A(Lon _temp-Lon _towfish)/2

D＝1/2arcsin[sinσ(cosθ-1/Asin(Lan _towfish)sinθ _linetgω)]

Lan _temp＝Lan _towfish+2D[B-3/2e′ ²Dsin(2Lan _towfish+4/3BD)]

And then can calculate the longitude and latitude (Lon of this target _Point, Lan _Point), calculation procedure is following:

$A=\sqrt{1+e^{\′2}{\cos }^4\left({\mathrm{Lan}}_{\mathrm{temp}}\right)}$

$B=\sqrt{1+e^{\′2}{\cos }^2\left({\mathrm{Lan}}_{\mathrm{temp}}\right)}$

$C=\sqrt{1+e^{\′2}}$

σ＝R ₁B ²/(aC)

Lon _point＝Lon _temp+1/Aarctg[(Atgσsin(θ _line±90)/(Bcos(Lan _temp)-tgσsin(Lan _temp)cos(θ _line±90)]

ω＝A(Lon _point-Lon _temp)/2

D＝1/2arcsin[sinσ(cos(θ _line+90)-1/Asin(Lan _temp)sin(θ _line±90)tgω)]

Lan _point＝Lan _temp+2D[B-3/2e′ ²Dsin(2Lan _temp+4/3BD)]

In above-mentioned steps, θ _LineIn ± 90 the calculating,, use θ for the left-side images of synthetic aperture sonar _Line+ 90, for the image right of synthetic aperture sonar, use θ _Line-90.

3. the framing system of a synthetic aperture sonar; Comprise: towed body, towboat, be installed on the towed body sound Doppler log, be installed on GPS, dry end signal processor, the transmitting transducer that is installed on the towed body side and receiving transducer array on the towboat; It is characterized in that the position of the same degree of depth respectively increases receiving transducer of installation respectively in the said towboat left and right sides, and an emission battle array is installed again at the front end of said towed body; Utilize this to be installed in two receiving transducers of towboat left and right sides; With a said emission battle array that is installed on the towed body, make its synchronous clock that sends through the electronic system in the said towed body carry out synchronous working, the signal that signal that receives through the said receiving transducer that is installed in the towboat left and right sides and said emission paroxysm are penetrated; Calculate; According to the gps data on the towboat, obtain locations of pixels in the image then

Wherein, the said emission battle array in that the front end of said towed body is installed is used to launch simple signal or linear FM signal,

The said receiving transducer that install the position of the same degree of depth in said towboat both sides; Receive the signal that the said emission paroxysm on the above-mentioned towed body is penetrated; Said dry end signal processor calculates the said receiving transducer that the is positioned at both sides distance apart from towed body respectively according to the signal of receiving, and according to the position that the towboat that GPS is confirmed is passed by, simulates a towboat flight path near straight line; Obtain the distance and bearing angle of towed body apart from this position of towboat

Then, by the distance and bearing angle of the above-mentioned towed body that draws apart from the towboat current location, and the position of the current towboat that records of GPS, utilize said dry end signal processor to calculate the position of towed body,

At last, the height that records according to sound Doppler log on the position of towed body, the towed body of said dry end signal processor and the length of synthetic aperture position that calculates each pixel in the image end of apart from.

Images