CN105388457A - Long-baseline hydroacoustic positioning method based on equivalent acoustic velocity gradient - Google Patents

Abstract

The invention discloses a long-baseline hydroacoustic positioning method based on the equivalent acoustic velocity gradient, and belongs to the field of hydroacoustic positioning navigation. A long-baseline hydroacoustic positioning system is used, a transmitting-receiving energy transducer carried on an object emits a positioning signal, a responder array laid in the seabed receives the positioning signal and returns a response signal, the spreading time of the acoustic signal from emission to return is measured, and mini acoustic velocity meters mounted on the transmitting-receiving energy transducer and the seabed responders are used to measure the acoustic velocity in real time; and according to the principle of equivalent acoustic velocity profile, the initial value is calculated by utilizing a historical acoustic velocity profile to search the equivalent acoustic velocity gradient, when the spreading distance from the transducers to the responder and that from the responders to the transducer are then same, the equivalent acoustic velocity gradient is determined, and the accurate position of the object is calculated. According to the invention, an accurate acoustic velocity profile, even an acoustic velocity profile, is not needed, influence of representative errors of the acoustic velocity profile is effective eliminated, and the positioning precision for the underwater object is improved.

Description

A kind of Long baselines hydrolocation method based on equivalent sound velocity gradient

Technical field

The invention belongs to hydrolocation navigation field, be specifically related to a kind of Long baselines hydrolocation method based on equivalent sound velocity gradient.

Background technology

Long baseline acoustic positioning system following range is large, and positioning precision is high, is widely applied in many-sides such as marine resources development, oceanographic engineering construction, under water archaeology, ocean national defense construction.The localization method of the long baseline acoustic positioning system many employings Distance Intersection researched and developed at present, the precision of range observation directly has influence on the positioning precision of long base line system, therefore carrying out sound ray according to actual measurement Sound speed profile corrects extremely important, but Sound speed profile is difficult to Real-time Obtaining, Sound speed profile representive error is difficult to avoid, and is therefore necessary to study a kind of long baseline acoustic positioning system effectively can eliminating the impact of Sound speed profile representive error.

Summary of the invention

For the above-mentioned technical matters existed in prior art, the present invention proposes a kind of Long baselines hydrolocation method based on equivalent sound velocity gradient, reasonable in design, overcome the deficiencies in the prior art, eliminate the error effect of Sound speed profile, improve precision.

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

A kind of Long baselines hydrolocation method based on equivalent sound velocity gradient, adopt long baseline acoustic positioning system, it transponder basic matrix be made up of multiple transponder comprising the process that is arranged on water surface ship and control module, be arranged on the transmitting-receiving transducer on water surface ship or underwater robot and be laid in seabed, described transmitting-receiving transducer and transponder basic matrix are all provided with miniature sound velocimeter;

The described Long baselines hydrolocation method based on equivalent sound velocity gradient is carried out in accordance with the following steps:

Step 1: absolute position calibration is carried out to the transponder basic matrix being laid in seabed;

Step 2: t two-way time being controlled transmitting-receiving transducer and transponder basic matrix measurement Acoustic Wave Propagation by process and control module _i, control by process and control module the velocity of sound C that transmitting-receiving transducer measured by miniature sound velocimeter ₀with the velocity of sound C ' of transponder _0i;

Step 3: calculate transmitting-receiving transducer to the approximate distance of each transponder and target approximate coordinates and each transponder to approximate distance and the target approximate coordinates of receiving and dispatching transducer;

Step 4: calculate target location accurately.

Preferably, in step 3, specifically comprise:

Step 3.1: utilize history Sound speed profile to calculate Approximate Equivalent sound velocity gradient g ₀, step-size in search Δ g is set, searches for equivalent sound velocity gradient g _ij:

g _ij＝g ₀+j·Δg(9)

In formula, i is sound ray sequence number, and j is searching times.

Step 3.2: utilize g _ijand measure the velocity of sound C of the transmitting-receiving transducer obtained ₀, sound wave t two-way time _i, calculate the approximate distance L of transmitting-receiving transducer to each transponder _ijand target approximate coordinates P _j(X _j, Y _j, Z _j);

Step 3.3: according to Sound speed profile integral area equal principle, calculates the equivalent sound velocity gradient g ' of transponder to transmitting-receiving transducer by formula (10) _ij:

g′ _ij＝g _ij-2(C′ _0i-C ₀)/(Z _i-Z _j)(10)

Wherein, C ₀, C ' _0ibe respectively the acoustic velocity value of transmitting-receiving transducer and the transponder obtained by miniature sound velocimeter measurement, Z _ifor the depth value of transponder, Z _jfor the target approximate coordinates P that step 3.2 calculates _j(X _j, Y _j, Z _j) depth value;

Step 3.4: utilize the g ' calculated _ijand measure the velocity of sound C ' of the transponder obtained _0i, sound wave t two-way time _i, calculate the approximate distance L ' of each transponder to transmitting-receiving transducer _ijand target approximate coordinates P ' _j(X ' _j, Y ' _j, Z ' _j).

Preferably, in step 4, specifically comprise:

Step 4.1: according to the distance L of the transmitting-receiving transducer calculated to each transponder _ijand each transponder is to the distance L ' of transmitting-receiving transducer _ij, make Δ L _ij=| L _ij-L' _ij|;

Step 4.2: according to round equidistant principle, as Δ L _ijget g during minimum value _ijvalue is actual equivalent sound velocity gradient g _ivalue, i.e. g _i=g _ij, adopt least square method to calculate target location P (X, Y, Z) accurately.

The Advantageous Effects that the present invention brings:

The present invention proposes a kind of Long baselines hydrolocation method based on equivalent sound velocity gradient, compared with prior art, Sound speed profile accurately can not be needed, even do not need Sound speed profile, eliminate the impact of Sound speed profile representive error on location Calculation precision, improve the positioning precision of long baseline acoustic positioning system.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of the Long baselines hydrolocation method medium-long baselines acoustic positioning system that the present invention is based on equivalent sound velocity gradient.

Fig. 2 is the FB(flow block) of the Long baselines hydrolocation method that the present invention is based on equivalent sound velocity gradient.

Fig. 3 is the calculating schematic diagram of equivalent sound velocity gradient in the present invention.

Fig. 4 be in the present invention equivalent sound velocity gradient with apart from poor graph of a relation.

Fig. 5 is seabed transponder basic matrix and target location schematic diagram in the present invention.

Fig. 6 be search in the present invention sound velocity gradient change with apart from poor graph of a relation.

Fig. 7 is the inventive method and additive method positioning error comparison diagram.

Wherein, 1-process and control module; 2-receives and dispatches transducer; 3-transponder; The miniature sound velocimeter of 4-.

Embodiment

Below in conjunction with accompanying drawing and embodiment, the present invention is described in further detail:

As shown in Figure 1, the transponder basic matrix be made up of multiple transponder 3 that long baseline acoustic positioning system comprises the process that is arranged on water surface ship and control module 1, the transmitting-receiving transducer 2 be arranged on ship or underwater robot, cloth are placed on seabed, described transmitting-receiving transducer 2 and transponder 3 are all provided with miniature sound velocimeter 4.

Process and control module 1 are responsible for storage and the calculating of measurement data, and control the operation of whole system.

Process and control module 1 control t two-way time of transmitting-receiving transducer and transponder basic matrix measurement Acoustic Wave Propagation _i, and control the velocity of sound C that transmitting-receiving transducer measured by miniature sound velocimeter ₀with the velocity of sound C ' of transponder _0i, the data t will measured afterwards _i, C ₀and C ' _0ibe stored in process and control module 1.

Because seawater is inhomogeneous interphase, the velocity of sound in seawater changes along with the change of temperature, saltiness and pressure, sound wave travel path is in the seawater a continuous print curve, according to equivalent sound velocity profile method principle, a real velocity of sound section normal gradient equivalent sound velocity profile can be replaced.According to the theory of ray acoustics, the track of sound ray in normal gradient layer is circular arc, and arc radius is:

R＝1/|pg|(1)

In formula, g is the sound velocity gradient value in normal gradient layer, and p is snell constant.

g＝(C _r-C ₀)/(Z _r-Z ₀)(2)

p＝sinθ ₀/C ₀＝sinθ _r/C _r(3)

In formula, C ₀for initial acoustic velocity value, can be obtained by the miniature sound velocimeter measurement of installing on the transducer; C _rfor stopping acoustic velocity value, calculated by formula (2) when sound velocity gradient g is known; Z ₀for transducer underwater penetration, Z _rfor the transponder place depth of water; θ ₀, θ _rbe respectively the initial incidence angle of sound wave and stop incident angle, θ ₀can be calculated by newton iteration formula by formula (4), θ _rcan be calculated by formula (5):

tan[arcsin(C _rsinθ ₀/C ₀)/2]-e ^tg/2tan(θ ₀/2)＝0(4)

θ _r＝2arctan(e ^tg/2tan(θ ₀/2))(5)

In formula, t measures the sound wave two-way time obtained, and g is equivalent velocity of sound Grad.

The vertical distance Δ z of Acoustic Wave Propagation, side direction are as follows apart from Δ x computing formula:

$\left\{\begin{array}{c}\mathrm{\Δ}z=R{\mathrm{sin\θ}}_r-R{\mathrm{sin\θ}}_0\\ \mathrm{\Δ}x=R{\mathrm{cos\θ}}_0-R{\mathrm{cos\θ}}_r\end{array}\right.---\left(6\right)$

Formula (6) is acoustic ray refraction correction formula, and the distance after correcting can be expressed as:

$L_i^2={\mathrm{\Δz}}^2+{\mathrm{\Δx}}^2---\left(7\right)$

Suppose existence 4 seabed transponders, then can utilize L _iadopt least square method to position to resolve:

$\left\{\begin{array}{c}{L}_1^2={\left(X-X_1\right)}^2+{\left(Y-Y_1\right)}^2+{\left(Z-Z_1\right)}^2\\ L_2^2={\left(X-X_2\right)}^2+{\left(Y-Y_2\right)}^2+{\left(Z-Z_2\right)}^2\\ L_3^2={\left(X-X_3\right)}^2+{\left(Y-Y_3\right)}^2+{\left(Z-Z_3\right)}^2\\ L_4^2={\left(X-X_4\right)}^2+{\left(Y-Y_4\right)}^2+{\left(Z-Z_4\right)}^2\end{array}\right.---\left(8\right)$

In formula, P (X, Y, Z) is the coordinate of transmitting-receiving transducer, P _i(X _i, Y _i, Z _i), (i=1,2,3,4) are the coordinate of transponder calibrated in the acoustic array of seabed.

At the equivalent sound velocity gradient g of reality _i, when (i=1,2,3,4) are known, utilize formula (1) ~ (8) target transducer coordinate can be obtained by iterative computation.But because real-time Sound speed profile is difficult to obtain, history Sound speed profile usually can only be utilized to calculate by the Approximate Equivalent sound velocity gradient g of transducer to transponder ₀if directly use g ₀calculate, Sound speed profile representive error must be introduced.

The present invention utilizes Approximate Equivalent sound velocity gradient g ₀, step-size in search Δ g is set, searches for equivalent sound velocity gradient g _ij:

g _ij＝g ₀+j·Δg(9)

In formula, i is sound ray sequence number, and j is searching times.

Utilize g _ijand measure the velocity of sound C of the transmitting-receiving transducer obtained ₀, sound wave t two-way time _i, iterative computation can go out receive and dispatch the approximate distance L of transducer to each transponder _ijand target approximate coordinates P _j(X _j, Y _j, Z _j);

Shown in composition graphs 3, the principle equal according to Sound speed profile integral area, by the equivalent sound velocity gradient g of transducer to transponder _ij, inverse transponder is to the equivalent sound velocity gradient g ' of transducer _ij:

g′ _ij＝g _ij-2(C′ _0i-C ₀)/(Z _i-Z _j)(10)

Wherein, C ₀, C ' _0ibe respectively the acoustic velocity value of transmitting-receiving transducer and the transponder obtained by miniature sound velocimeter measurement, Z _ifor the depth value of transponder, Z _jfor target approximate coordinates P _j(X _j, Y _j, Z _j) in water depth value;

In like manner, g ' is utilized _ijand measure the velocity of sound C ' of the transponder obtained _0i, sound wave t two-way time _i, can each transponder of iterative computation to the approximate distance L ' of transducer _ij, approximate coordinates P ' _j(X ' _j, Y ' _j, Z ' _j).

According to round equidistant principle, L _ijwith L ' _ijshould be equal, namely apart from poor Δ L _ij=| L _ij-L ' _ij|=0, if but the equivalent sound velocity gradient g of search _ijthere is error, then Δ L _ij≠ 0, and g _ijerror is larger, apart from poor Δ L _ijlarger.As shown in Figure 4, equivalent sound velocity gradient with apart from poor graph of a relation, when searching for equivalent sound velocity gradient and reaching 0.05, namely search for the equivalent sound velocity gradient of equivalent sound velocity gradient and reality equal, now Δ L _ij=0.

Characteristic accordingly, then the method by search obtains the equivalent sound velocity gradient g of transducer to each transponder _i, then calculated target location P (X, Y, Z) accurately by formula (1) ~ (8).

A kind of Long baselines hydrolocation method (as shown in Figure 2) based on equivalent sound velocity gradient of the present invention, carry out in accordance with the following steps:

Step 1: carry out absolute position calibration to the transponder basic matrix being laid in seabed, controls t two-way time of transmitting-receiving transducer and transponder basic matrix measurement Acoustic Wave Propagation by process and control module _i, control by process and control module the velocity of sound C that transmitting-receiving transducer measured by miniature sound velocimeter ₀with the velocity of sound C ' of transponder _0i, utilize GNSS to measure the position coordinates of transmitting-receiving transducer simultaneously; Wherein to the distance L between transmitting-receiving transducer and transponder _isound ray correcting method, consistent with the method implemented when locating object;

Step 2: t two-way time being controlled transmitting-receiving transducer and transponder basic matrix measurement Acoustic Wave Propagation by process and control module _i, control by process and control module the velocity of sound C that transmitting-receiving transducer measured by miniature sound velocimeter ₀with the velocity of sound C ' of transponder _0i;

Step 3: utilize history Sound speed profile to calculate Approximate Equivalent sound velocity gradient g ₀, search for the equivalent sound velocity gradient g of transducer to transponder within the specific limits _ij, calculate the distance L of transducer to each transponder _ij, target approximate coordinates P _j(X _j, Y _j, Z _j), inverse transponder is to the equivalent sound velocity gradient g ' of transducer _ij, calculate the distance L ' of transponder to transducer _ijand target approximate coordinates P ' _j(X ' _j, Y ' _j, Z ' _j);

Step 4: according to the distance L of the transmitting-receiving transducer calculated to each transponder _ijand each transponder is to the distance L ' of transmitting-receiving transducer _ij, make Δ L _ij=| L _ij-L' _ij|; According to round equidistant principle, judge Δ L _ij=| L _ij-L' _ij| whether can get minimum value;

If: judged result is Δ L _ij=| L _ij-L' _ij| can minimum value be got, then as Δ L _ijget g during minimum value _ijvalue is actual equivalent sound velocity gradient g _ivalue, i.e. g _i=g _ij, adopt least square method to calculate target location P (X, Y, Z) accurately;

Or judged result is Δ L _ij=| L _ij-L' _ij| get less than minimum value, then perform step 3.

Computer Simulation is carried out to method of the present invention, shown in composition graphs 5, in certain marine site that the depth of water is 500m, the square net form being 500m by the length of side lays seabed acoustic array, the target place degree of depth is 100m, and the velocity of sound is 1500m/s, and target is respectively 0.04,0.05,0.06,0.07 to the equivalent sound velocity gradient of four transponders, miniature sound velocimeter measuring accuracy is 0.02m/s, and transponder basic matrix calibration accuracy is in-plane 20cm, vertical direction 20cm.Suppose that the equivalent sound velocity gradient utilizing history Sound speed profile to calculate is 0.04, survey region measurement Sound speed profile, its equivalent sound velocity gradient is 0.05.Adopt the inventive method to position calculating to submarine target, meanwhile, employing history Sound speed profile, actual measurement Sound speed profile position calculating, and compare analysis to the positioning precision of three kinds of methods respectively.

When target is in diverse location, the inventive method is utilized to position calculating to target, obtain search sound velocity gradient change with apart from poor relation as shown in Figure 6, the target finally determined is respectively 0.0395,0.05,0.06,0.07 to the equivalent sound velocity gradient of four transponders, differ 0.0005 with given value is maximum, can find out that adopting the inventive method accurately to search for obtains equivalent sound velocity gradient.

Shown in composition graphs 7, can find out that the plane error and vertical error that adopt the inventive method location Calculation are all at decimeter grade, wherein plane error average out to 0.2m, vertical error average out to 0.1m; When adopting history Sound speed profile to position calculating, plane error average out to 1.8m, vertical error average out to 1.3m; When adopting actual measurement Sound speed profile to position calculating, plane error average out to 1.7m, vertical error average out to 0.5m.

Therefore, compared with employing history Sound speed profile method, actual measurement Sound speed profile is adopted to improve the precision of location Calculation, but the impact of Sound speed profile representive error can not be eliminated, and the Long baselines hydrolocation method that the present invention proposes can not need Sound speed profile accurately, even do not need Sound speed profile, effectively eliminate the impact of Sound speed profile representive error, improve the precision of Long baselines hydrolocation.

Certainly, above-mentioned explanation is not limitation of the present invention, and the present invention is also not limited in above-mentioned citing, and the change that those skilled in the art make in essential scope of the present invention, remodeling, interpolation or replacement also should belong to protection scope of the present invention.

Claims (3)

1. the Long baselines hydrolocation method based on equivalent sound velocity gradient, adopt long baseline acoustic positioning system, it transponder basic matrix be made up of multiple transponder comprising the process that is arranged on water surface ship and control module, be arranged on the transmitting-receiving transducer on water surface ship or underwater robot and be laid in seabed, described transmitting-receiving transducer and transponder basic matrix are all provided with miniature sound velocimeter;

It is characterized in that: the described Long baselines hydrolocation method based on equivalent sound velocity gradient is carried out in accordance with the following steps:

Step 1: absolute position calibration is carried out to the transponder basic matrix being laid in seabed;

Step 2: t two-way time being controlled transmitting-receiving transducer and transponder basic matrix measurement Acoustic Wave Propagation by process and control module _i, control by process and control module the velocity of sound C that transmitting-receiving transducer measured by miniature sound velocimeter ₀with the velocity of sound C ' of transponder _0i;

Step 3: calculate transmitting-receiving transducer to the approximate distance of each transponder and target approximate coordinates and each transponder to approximate distance and the target approximate coordinates of receiving and dispatching transducer;

Step 4: calculate target location accurately.

2. the Long baselines hydrolocation method based on equivalent sound velocity gradient according to claim 1, is characterized in that: in step 3, specifically comprises:

Step 3.1: utilize history Sound speed profile to calculate Approximate Equivalent sound velocity gradient g ₀, step-size in search Δ g is set, searches for equivalent sound velocity gradient g _ij:

g _ij＝g ₀+j·Δg(9)

In formula, i is sound ray sequence number, and j is searching times.

Step 3.2: utilize g _ijand measure the velocity of sound C of the transmitting-receiving transducer obtained ₀, sound wave t two-way time _i, calculate the approximate distance L of transmitting-receiving transducer to each transponder _ijand target approximate coordinates P _j(X _j, Y _j, Z _j);

Step 3.3: according to Sound speed profile integral area equal principle, calculates the equivalent sound velocity gradient g ' of transponder to transmitting-receiving transducer by formula (10) _ij:

g′ _ij＝g _ij-2(C′ _0i-C ₀)/(Z _i-Z _j)(10)

Wherein, C ₀, C ' _0ibe respectively the acoustic velocity value of transmitting-receiving transducer and the transponder obtained by miniature sound velocimeter measurement, Z _ifor the depth value of transponder, Z _jfor the target approximate coordinates P that step 3.2 calculates _j(X _j, Y _j, Z _j) depth value;

Step 3.4: utilize the g ' calculated _ijand measure the velocity of sound C ' of the transponder obtained _0i, sound wave t two-way time _i, calculate the approximate distance L ' of each transponder to transmitting-receiving transducer _ijand target approximate coordinates P ' _j(X ' _j, Y ' _j, Z ' _j).

3. the Long baselines hydrolocation method based on equivalent sound velocity gradient according to claim 1, is characterized in that: in step 4, specifically comprises:

Step 4.1: according to the distance L of the transmitting-receiving transducer calculated to each transponder _ijand each transponder is to the distance L ' of transmitting-receiving transducer _ij, make Δ L _ij=| L _ij-L ' _ij|;

Step 4.2: according to round equidistant principle, as Δ L _ijget g during minimum value _ijvalue is actual equivalent sound velocity gradient g _ivalue, i.e. g _i=g _ij, adopt least square method to calculate target location P (X, Y, Z) accurately.