CN110412546A - A method and system for locating underwater targets - Google Patents

Abstract

The present invention gives a kind of localization methods and system for submarine target, and the underwater sound signal sent including obtaining signal source acquires the underwater sound signal intensity of target current location；Pad value based on Gradient correction algorithm and underwater sound signal intensity calculates target at a distance from signal source；The estimated position that target is calculated using inertial navigation technology is carried out the amendment of target athletic posture position to estimated position using distance, obtains the correction position of target；Precision based on estimated position and correction position sets corresponding weighted value, and estimated position and correction position are weighted least square, obtain the location information of target.It is calculated by the weighted least-squares to estimated position and correction position, greatly improves the precision of Underwater Navigation, compared with the existing reckoning positioning based on SINS, locating effect is more accurate.

Description

A method and system for locating underwater targets

This application claims the priority of the Chinese patent application filed on June 27, 2019 with the application number 201910566875.0 and the invention titled "A Positioning Method and System for Underwater Targets", the entire contents of which are by reference Incorporated in this application.

technical field

The invention relates to the technical field of hydroacoustics and signal processing, in particular to a positioning method and system for underwater targets.

Background technique

In recent years, with the rapid development of electronic technology and the accelerated pace of underwater development, underwater unmanned vehicles have been widely used, whether it is underwater detection, underwater combat, seawater underwater reconnaissance. In practical applications, underwater UAVs often need to achieve long-term self-positioning functions, and the time may be as long as half a year. This requires that the power consumption of the underwater vehicle should not be too high, and the positioning algorithm needs to have better long-term stability.

Common underwater self-positioning methods are mainly based on measuring the propagation time of the signal and the arrival angle of the signal to measure the position of the current target from the beacon. At this time, in order to calculate the position of the target, multiple beacons are often used for simultaneous calculation. Such as long baseline positioning system, short baseline positioning system. Because the ultra-short baseline positioning system is an array processing method, its array element distribution is relatively concentrated and can be regarded as a single point source. Although this type of technology is very mature, generally speaking, the system hardware cost of time delay measurement is high, and the time synchronization problem needs to be considered. At the same time, the change of sound speed in the ocean is more variable, which will bring greater interference. . Similarly, the angle of arrival is generally based on array signal processing, which requires that the target itself needs to carry more complex hardware facilities, and the power consumption also increases.

In addition, there are many single-beacon self-localization technologies currently combined with target motion and attitude information. For example, based on the basic principle of Kalman filtering, extended Kalman, unscented Kalman filtering and various derived improved algorithms. Of course, it also includes derived and improved algorithms such as particle filter algorithms based on the basic principle of Bayesian filtering. The basic principle of these algorithms is to establish the state transition equation and the measurement equation to locate the target. In the system of measuring time delay, this kind of algorithm has the characteristics of low measurement error due to high hardware support. If the marine environment is relatively stable, it has higher positioning accuracy. However, with various changes in the environment, the equations established often bring great errors, which in turn affects the effect of the algorithm itself.

SUMMARY OF THE INVENTION

The present invention provides a positioning method and system for underwater targets.

In one aspect, the present invention provides a method for locating an underwater target, the method comprising the following steps:

S1: Obtain the underwater acoustic signal sent by the signal source, and collect the underwater acoustic signal strength at the current position of the target;

S2: Calculate the distance between the target and the signal source based on the slope correction algorithm and the attenuation value of the underwater acoustic signal strength;

S3: use the inertial navigation technology to calculate the estimated position of the target, and use the distance to correct the estimated position of the target movement and posture, and obtain the corrected position of the target;

S4: Based on the accuracy of the estimated position and the corrected position, set a corresponding weight value, and use the estimated position and the corrected position to perform weighted least squares to obtain the position information of the target.

In a specific embodiment, the signal source is a single beacon signal source. A beacon is used to transmit energy, the implementation is simple, and it is easy to carry and install.

In a preferred embodiment, the distance calculation in step S2 also uses a curve filtering algorithm to filter outliers of signal strength, and the method for filtering outliers in the curve filtering algorithm is: calculating the difference _ΔPk of underwater acoustic signal strength between the current moment and the previous moment , and the difference ΔP _{k -1} of the underwater acoustic signal intensity at the latest moment corresponding to ΔP k, based on the heading information of the target and the value of ΔP _k -ΔP _k-1 to determine whether the underwater acoustic signal intensity value at the current moment is an outlier, if the current If the underwater acoustic signal strength at the moment is an outlier, then filter the underwater acoustic signal strength value at that moment. The curve filtering algorithm can effectively filter the abnormal signal strength value in the signal acquisition, and effectively avoid the positioning error caused by the abnormal value.

In a specific embodiment, the specific way of judging the outlier is: if the heading information is far away from the signal source and ΔP _k >ΔP _k-1 , the underwater acoustic signal strength value at the current moment is an outlier; if the heading information is close to the signal source signal source, and ΔP _k is less than ΔP _k-1 , the underwater acoustic signal strength value at the current moment is an outlier.

In a specific embodiment, the calculation formula of the distance between the target and the signal source is: Among them, I _r is the intensity of the underwater acoustic signal at the current position, I ₀ is the intensity of the reference underwater acoustic signal, and n is the attenuation factor.

In a specific embodiment, the calculation method of the reference underwater acoustic signal strength I ₀ and the attenuation factor n is: collect parameter values [I _a , a] and [I _b , b] of at least two points in the current water area, and use Formula I _a =I ₀ +nlg(a), I _b =I ₀ +nlg(b) to calculate the reference underwater acoustic signal strength I ₀ and attenuation factor n of the current water area; where I _a and I _b represent two acquisitions respectively The underwater acoustic signal strength value of the point, a and b respectively represent the distance between the two collection points and the signal source.

In a specific embodiment, the formula for calculating the position of the target point is: Among them, H represents the coefficient matrix, W is the covariance matrix of the estimated error of the X system, and z represents the position measurement value.

In a specific embodiment, the weight value is set in the following manner: the precision of the location information is proportional to the weight value.

According to a second aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, the computer program being executed by a computer processor for the above-mentioned method.

According to a third aspect of the present invention, a positioning system for an underwater target is proposed, the system comprising:

Signal acquisition unit: configured to acquire the underwater acoustic signal sent by the beacon, and to collect the underwater acoustic signal strength of the current position of the target;

Distance measurement unit: configured to calculate the distance between the target and the beacon based on the slope correction algorithm and the attenuation value of the underwater acoustic signal strength;

Position correction unit: configured to use inertial navigation technology to calculate the estimated position of the target, and use the distance to correct the estimated position to obtain the corrected position of the target;

Position calculation unit: configured to perform weighted least squares on the estimated position and the corrected position to obtain the position information of the target.

The present invention uses underwater acoustic signal strength information to collect and analyze, combines the intensity attenuation and the mapping inertia of the distance to estimate the distance information between the current target itself and the beacon, uses the slope correction algorithm to specifically calculate the distance between the target and the beacon, and uses The curve filtering algorithm filters outliers, calculates the position based on the target's own attitude information, uses the calculated distance value to correct the estimated position, and finally performs weighted least squares on the corrected position and the estimated position to obtain more accurate target position information . The positioning system IPF-RSS based on the loss of underwater acoustic signal strength combines the existing inertial navigation technology SINS, and uses the weighted least squares to design a single-beacon self-positioning system, which greatly improves the accuracy of underwater positioning, and is consistent with the current situation. Compared with the dead reckoning positioning based on SINS, the positioning effect is better.

Description of drawings

The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated into and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain the principles of the invention. Other embodiments and many of the intended advantages of the embodiments will be readily recognized as they become better understood by reference to the following detailed description. Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

1 is a flowchart of a method for locating an underwater target according to an embodiment of the present invention;

2 is a schematic diagram of an effect diagram of underwater target positioning according to a specific embodiment of the present invention;

Fig. 3 is the algorithm flow chart of the signal strength distance measurement process of a specific embodiment of the present invention;

4 is a frame diagram of a positioning system for an underwater target according to an embodiment of the present invention;

FIG. 5 is a structural frame diagram of a self-positioning system based on attenuation of underwater acoustic signal strength according to a specific embodiment of the present invention.

Detailed ways

The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the related invention, but not to limit the invention. In addition, it should be noted that, for the convenience of description, only the parts related to the related invention are shown in the drawings.

It should be noted that the embodiments in the present application and the features of the embodiments may be combined with each other in the case of no conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

According to a method for locating an underwater target according to an embodiment of the present invention, FIG. 1 shows a flowchart of a method for locating an underwater target according to an embodiment of the present invention. As shown in Figure 1, the method includes the following steps:

S101: Acquire the underwater acoustic signal sent by the signal source, and collect the underwater acoustic signal strength at the current position of the target. The hydrophone is used to obtain the intensity of the current positioning underwater acoustic signal, which greatly reduces the cost of the equipment.

In a preferred embodiment, the hydrophone can be a general hydrophone, and the strength information of the current positioning signal can be obtained by adding a power amplifier. There is no need to use an array transducer array to collect signals, and no need for various high-end digital processor platforms to achieve time synchronization, which greatly reduces the cost and volume power consumption of the equipment.

In a preferred embodiment, the signal source is sent by a single beacon, which is analogous to GPS signals in space. As shown in the schematic diagram of the system effect shown in Figure 2, the beacon only sends positioning signals on the sea surface, and the positioning objects it serves can be arbitrarily many. indivual. There is no concept of communication between the beacon itself and the target that needs location information, and only the beacon sends signals unilaterally, which makes the positioning target itself do not need to send signals, which greatly reduces the energy output and simplifies the hardware configuration. .

S102: Calculate the distance between the target and the signal source based on the slope correction algorithm and the attenuation value of the underwater acoustic signal strength. The distance measurement method based on the received underwater acoustic signal strength can meet the requirements of low power consumption, high concealment, and fast positioning response.

In a preferred embodiment, a slope correction algorithm is used to calculate the distance between the target and the signal source. The formula for calculating the distance between the target and the signal source is: Among them, I _r is the intensity of the underwater acoustic signal at the current position, I ₀ is the intensity of the reference underwater acoustic signal, and n is the attenuation factor.

In a specific embodiment, under the same water conditions, the reference underwater acoustic signal strength I ₀ will be a fixed value, and the attenuation factor n fluctuates little, which is also regarded as a fixed value. At least two sets of different parameter values [I _a , a] and [I _b , b] . . . are obtained by performing at least two measurements in the current water area, based on the formula I _a =I ₀ +nlg(a), I _b =I ₀ +nlg(b), solve the quadratic equation, and calculate the underwater acoustic signal strength I ₀ and attenuation factor n of the current water area, where I _a and I _b represent the underwater acoustic signal strength values of the two collection points respectively , a and b respectively represent the distance between the two collection points and the signal source.

In a preferred embodiment, a curve filtering algorithm is used to filter outliers of the underwater acoustic signal. The method of filtering outliers of the curve filtering algorithm is: calculating the difference ΔP _k of the underwater acoustic signal intensity between the current moment and the previous moment, and the difference ΔP _k-1 of the underwater acoustic signal intensity at the latest moment corresponding to ΔP _k , based on the heading of the target The information and the value of ΔP _k -ΔP _k-1 determine whether the underwater acoustic signal strength value at the current moment is an outlier. If the underwater acoustic signal strength at the current moment is an outlier, filter the underwater acoustic signal strength value at this moment.

In a specific embodiment, the specific judgment method of the outlier is: if the heading information is far away from the signal source, and ΔP _k >ΔP _k-1 , the underwater acoustic signal strength value at the current moment is an outlier; In order to be close to the signal source, and ΔP _k is less than ΔP _k-1 , the underwater acoustic signal strength value at the current moment is an outlier.

S103: Calculating the estimated position of the target by using an inertial navigation technology, and correcting the estimated position by using the distance to correct the movement posture and position of the target, so as to obtain the corrected position of the target. Through inertial navigation SINS technology, relevant parameters such as the current speed information, position information, heading information, pitch angle and roll angle of the target can be obtained. The positioning error has the problem of cumulative error, and the calculated distance can be used to correct it to reduce the positioning error. The positioning deviation caused by accumulation is too large.

In a specific embodiment, it is assumed that the estimated position of the target measured by the inertial navigation SINS technology is X _SINS , and the distance measured by the slope correction algorithm and the curve filtering algorithm is L _RSS ; and the variances measured by the two are respectively is σ _S , σ _R . In order to obtain more accurate estimation results, according to the basic idea of weighted least squares algorithm and particle filter algorithm, a distance correction algorithm based on target motion attitude is proposed, that is, X _SINS is corrected by the measured L _RSS .

In a specific embodiment, the correction algorithm is as follows: in the range of the interval [X _SINS -σ _S , X _SINS +σ _S ], N particle point sets Γ={X _S1 , X _S2 , L, X _SN } are selected to represent The coordinate set of the particle, then the distance set between the particle set and the sound source is D=Γ-S ₀ , where S ₀ is the sound source coordinate. Take the point X _SINS-RSS = {DL _RSS } _min with the highest probability between the distance set D and L _RSS , that is, the closest Euclidean distance, as the corrected position result. (The formula is summarized below)

D=Γ(X)-S ₀ , X∈[X _SINS -σ _S , X _SINS +σ _S ]

X _SINS-RSS = {DL _RSS } _min

S104: Based on the accuracy of the estimated position and the corrected position, set a corresponding weight value, and perform weighted least squares between the estimated position and the corrected position to obtain the position information of the target.

In a specific embodiment, the specific calculation formula of the target position is:

It is assumed that the estimated position of the target measured by the inertial navigation SINS technology is X _SINS , and the corrected position obtained from the above is X _SINS-RSS . That is, two different estimation results obtained from two systems with different measurement precisions. If X _real is the real distance, there is a SINS estimation system X _SINS =X _real +V _SINS , where V _SINS represents the estimation error of the system. Similarly, for In the system corrected by the attitude, X _SINS-RSS =X _real +V _SINS-RSS , and V _SINS-RSS is also the estimated error of the current system. Combine the two measurement system results with:

Then there is an estimation result by weighted least squares

where W is the covariance matrix of V.

In a specific embodiment, the weight value is set in the following manner: the precision of the location information is proportional to the weight value. For example, the weights of the estimated position and the corrected position are set to 40% and 60% according to the accuracy. It should be recognized that the weight value may be set to other values according to the actual measurement and calculation scenarios and the system, so as to meet the calculation requirements in different scenarios.

FIG. 3 shows an algorithm flow chart of a signal strength distance measurement process according to a specific embodiment of the present invention. The method specifically includes the following steps:

S301: Use an underwater acoustic signal acquisition and input module to acquire the received underwater acoustic signal. The current positioning signal information can be obtained by using the hydrophone plus the power amplifier. Greatly reduces the cost and volume power consumption of the device.

S302: Signal strength analysis. Based on the obtained underwater acoustic signal, the intensity information of the underwater acoustic signal is obtained by analysis.

S303: signal strength outlier removal. Remove signal strength outliers and perform distance calculations based on signal strength.

In a specific embodiment, the ranging algorithm specifically includes a slope correction algorithm 3031 , a curve filtering algorithm 3032 and a one-dimensional WLS-IPF algorithm 3033 .

In a specific embodiment, the specific implementation of the slope correction algorithm 3031 is:

Two measurements with different parameter values are and And the amplitude of the underwater acoustic signal received at the same sound source distance d corresponds to but

Assuming that curve 1 is known, its corresponding parameters n ₁ and Substitute the currently received strength Calculate an estimate for:

And the actual value is d, then its distance estimation error The ratio k of the corresponding calculated error to the actual distance:

And the actual distance according to the curve b has Then the above formula can be transformed into A function expression with parameters:

Perform logarithmic transformation processing and combine common factors as follows:

in,

At the same time, assuming that the actual values of the first three points of curve 2 have been obtained, α and β can be calculated according to the above formula. This can then be based on the actual measured value Correct the estimation error.

In a specific embodiment, the specific implementation of the curve filtering algorithm 3032 is as follows: using the curve filtering algorithm to filter the abnormal value of the underwater acoustic signal. The method of filtering outliers of the curve filtering algorithm is: calculating the difference ΔP _k of the underwater acoustic signal intensity between the current moment and the previous moment, and the difference ΔP _k-1 of the underwater acoustic signal intensity at the latest moment corresponding to ΔP _k , based on the heading of the target The information and the value of ΔP _k -ΔP _k-1 determine whether the underwater acoustic signal strength value at the current moment is an outlier. If the underwater acoustic signal strength at the current moment is an outlier, filter the underwater acoustic signal strength value at this moment. The specific judgment method of the outlier is: if the heading information is far away from the signal source, and ΔP _k >ΔP _k-1 , the underwater acoustic signal strength value at the current moment is an outlier; if the heading information is close to the signal source, And ΔP _k is less than ΔP _k-1 , then the underwater acoustic signal strength value at the current moment is an outlier.

In a specific embodiment, the specific calculation formula of the one-dimensional WLS-IPF algorithm 3033 is: L=(H ^T R ^-1 H) ^-1 H ^T R ^{- 1} Z ₁ , where H represents the coefficient matrix (transpose) , R represents the covariance matrix Z ₁ represents the distance measurement matrix.

S304: Distance mapping algorithm. That is, the relationship between the distance d and the current received signal strength I is represented.

The specific calculation formula is: Among them, I _r is the intensity of the underwater acoustic signal at the current position, I ₀ is the intensity of the reference underwater acoustic signal, and n is the attenuation factor.

FIG. 4 shows a frame diagram of a positioning system for an underwater target according to an embodiment of the present invention. The system includes a signal acquisition unit 401 , a distance measurement unit 402 , a position correction unit 403 and a position calculation unit 404 .

In a specific embodiment, the signal acquisition unit 401 is configured to acquire the underwater acoustic signal sent by the beacon, and collect the intensity of the underwater acoustic signal at the current position of the target. The signal acquisition unit 401 includes a hydrophone and a power amplifier.

In a preferred embodiment, the hydrophone can be a general hydrophone, and the strength information of the current positioning signal can be obtained by adding a power amplifier. There is no need to use an array transducer array to collect signals, and no need for various high-end digital processor platforms to achieve time synchronization, which greatly reduces the cost and volume power consumption of the equipment.

In a preferred embodiment, the beacon adopts a single beacon configuration, the beacon just sends a positioning signal on the sea surface, and the positioning objects it serves can be any number. There is no concept of communication between the beacon itself and the target that needs location information, and only the beacon sends signals unilaterally, which makes the positioning target itself do not need to send signals, which greatly reduces the energy output and simplifies the hardware configuration. .

In a specific embodiment, the distance calculation unit 402 is configured to calculate the distance between the target and the beacon based on a slope correction algorithm and the attenuation value of the underwater acoustic signal strength. The position correction unit 403 is configured to calculate the estimated position of the target using inertial navigation technology, and to correct the estimated position using the distance to obtain the corrected position of the target. The position calculation unit 404 is configured to perform weighted least squares on the estimated position and the corrected position to obtain position information of the target. Through the operation of a series of algorithms of the distance measurement unit 402 , the position correction unit 403 and the position calculation unit 404 , errors in each algorithm are eliminated to a certain extent, and more accurate target positioning information can be finally obtained.

In a preferred embodiment, a strapdown inertial navigation device is provided on the target to obtain speed information, heading information and position information of the target. The strapdown inertial navigation device can quickly obtain the current speed information and heading information of the target, and can calculate the position according to the speed information and heading information, and can estimate the position information of the target at different times as the reference data of the above algorithm.

FIG. 5 shows a structural frame diagram of a self-positioning system based on attenuation of underwater acoustic signal strength according to a specific embodiment of the present invention. The system includes a distance acquisition module 501 , an inertial navigation module 502 , a fusion algorithm WLS-IPF module 503 and location information 404 . The position information data obtained by the distance acquisition module 501 and the inertial navigation module 502 are calculated by the fusion algorithm WLS-IPF module 503 and finally output position information 504 . Using the fusion algorithm WLS-IPF module to perform data fusion operation, the error of the data acquired by the distance acquisition module 501 and the inertial navigation module 502 is reduced, and the calculated position information is more accurate.

In a specific embodiment, the distance acquisition module 501 includes an underwater acoustic signal acquisition and input unit 5011 , a signal strength analysis unit 5012 , a signal strength outlier removal unit 5013 and a distance mapping unit 5014 , which are connected in sequence. The distance acquisition module 501 uses the signal strength to calculate the distance and position, which can meet the requirements of low power consumption, high concealment, and fast positioning response.

In a specific embodiment, the inertial navigation module 502 includes a gyroscope 5021, an accelerometer 5022 and an electronic compass 5023, and obtains the speed 5024 and the attitude angle 5025 of the target through the operation of the gyroscope 5021, the accelerometer 5022 and the electronic compass 5023. The inertial navigation module 502 can obtain relevant parameters such as the current speed information, position information, heading information, pitch angle and roll angle of the target based on the SINS technology, which can be used to provide a data basis for subsequent distance correction or position correction calculations.

Embodiments of the present invention also relate to a computer-readable storage medium having stored thereon a computer program that, when executed by a computer processor, implements the above method. The computer program contains program code for carrying out the method shown in the flowchart. It should be noted that the computer-readable medium of the present application may be a computer-readable signal medium or a computer-readable medium, or any combination of the above two.

The present invention uses underwater acoustic signal strength information to collect and analyze, combines the intensity attenuation and the mapping inertia of the distance to estimate the distance information between the current target itself and the beacon, uses the slope correction algorithm to specifically calculate the distance between the target and the beacon, and uses The curve filtering algorithm filters outliers, calculates the position based on the target's own attitude information, uses the calculated distance value to correct the estimated position, and finally performs weighted least squares on the corrected position and the estimated position to obtain more accurate target position information . The positioning system IPF-RSS based on the loss of underwater acoustic signal strength combines the existing inertial navigation technology SINS, and uses the weighted least squares to design a single-beacon self-positioning system, which greatly improves the accuracy of underwater positioning, and is consistent with the current situation. Compared with the dead reckoning positioning based on SINS, the positioning effect is better.

This application is based on research results funded by the National Natural Science Foundation of China 61671394 and the Central Universities Fundamental Research Funds Special Fund (20720170044).

The above description is only a preferred embodiment of the present application and an illustration of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solution formed by the specific combination of the above technical features, and should also cover the above technical features or Other technical solutions formed by any combination of its equivalent features. For example, a technical solution is formed by replacing the above-mentioned features with the technical features disclosed in this application (but not limited to) with similar functions.

Claims (10)

1. a positioning method for underwater target, is characterized in that, comprises the following steps: S1: Obtain the underwater acoustic signal sent by the signal source, and collect the underwater acoustic signal strength at the current position of the target; S2: Calculate the distance between the target and the signal source based on the slope correction algorithm and the attenuation value of the underwater acoustic signal strength; S3: using inertial navigation technology to calculate the estimated position of the target, and using the distance to correct the target movement posture position for the estimated position to obtain the corrected position of the target; S4: Based on the accuracy of the estimated position and the corrected position, set a corresponding weight value, and use the estimated position and the corrected position to perform weighted least squares to obtain the position information of the target. 2 . The method for positioning an underwater target according to claim 1 , wherein the signal source is a single beacon signal source. 3 . 3. the positioning method for underwater target according to claim 1, is characterized in that, the calculation formula of the distance of described target and described signal source is: Among them, I _r is the intensity of the underwater acoustic signal at the current position, I ₀ is the intensity of the reference underwater acoustic signal, and n is the attenuation factor. 4. the positioning method for underwater target according to claim 3, is characterized in that, in described step S2, distance calculation also adopts curve filtering algorithm to filter signal strength outliers, and the filtering signal outliers of described curve filtering algorithm The method is: calculating the difference ΔP _k of the underwater acoustic signal strength between the current moment and the previous moment, and the difference ΔP _k-1 of the underwater acoustic signal strength at the latest moment corresponding to ΔP _k , based on the heading information of the target and ΔP _k -ΔP The value of _k-1 determines whether the underwater acoustic signal intensity value at the current moment is an outlier. If the underwater acoustic signal intensity at the current moment is an outlier, filter the underwater acoustic signal intensity value at this moment. 5 . The method for positioning an underwater target according to claim 4 , wherein the specific judgment method of the outlier is: if the heading information is far away from the signal source, and ΔP _k >ΔP _k-1 , the underwater acoustic signal strength value at the current moment is an outlier; if the heading information is close to the signal source and ΔP _k is less than ΔP _k-1 , the underwater acoustic signal strength value at the current moment is an outlier value. 6. The method for positioning an underwater target according to claim 5, wherein the calculation method of the reference underwater acoustic signal strength I ₀ and the attenuation factor n is: collecting at least 2 The parameter values [I _a , a] and [I _b , b] of the point, use the formula I _a =I ₀ +nlg(a), I _b =I ₀ +nlg(b) to calculate the reference hydroacoustic signal of the current water area Intensity I ₀ and the attenuation factor n; wherein I _a and I _b respectively represent the intensity values of the underwater acoustic signals of the two collection points, and a and b respectively represent the distances between the two collection points and the signal source. 7. the positioning method for underwater target according to claim 1, is characterized in that, the position calculation formula of described target point is: Among them, H represents the coefficient matrix, W is the covariance matrix of the estimated error of the system, and Z represents the measurement position matrix of the two systems. 8 . The method for positioning an underwater target according to claim 1 , wherein the weight value is set in a manner that: the accuracy of the position information is proportional to the weight value. 9 . 9. A computer-readable storage medium on which a computer program is stored, characterized in that, when the computer program is executed by a computer processor, the method according to any one of claims 1 to 8 is implemented. 10. A positioning system for underwater targets, comprising: Signal acquisition unit: configured to acquire the underwater acoustic signal sent by the beacon, and to collect the underwater acoustic signal strength of the current position of the target; Distance measurement unit: configured to calculate the distance between the target and the beacon based on a slope correction algorithm and the attenuation value of the underwater acoustic signal strength; Position correction unit: configured to use inertial navigation technology to calculate the estimated position of the target, and use the distance to correct the estimated position to obtain the corrected position of the target; A position calculation unit: configured to perform weighted least squares on the estimated position and the corrected position to obtain position information of the target.