An underwater target motion state evaluation method based on a distributed sound barrier system

Abstract

This application belongs to the field of underwater acoustic detection technology. This application provides a method for evaluating the motion state of an underwater target based on a distributed sound barrier system. In the embodiments of the present disclosure, the two-dimensional coordinates of the target when it first crosses the sound barrier, the target speed, and the navigation angle are used as the parameters to be estimated, and the parameter estimation problem is transformed into a problem of solving a system of linear equations; the time delay difference of the target crossing the sound barrier is substituted into the equation to solve the estimation of the target motion state, and further calculate the distance between the target and the sound source when the target crosses each sound barrier. Under the minimum standard that the product of the number of sound sources and receivers is not less than 4, this method can be used for any sound transmission system composed of multiple sound sources and receivers, with stronger versatility and accurate and reliable state estimation results.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of underwater acoustic detection technology, and in particular, to a method for evaluating the motion state of an underwater target based on a distributed acoustic barrier system. Background Art

[0002] Research shows that a distributed active acoustic transmission system forms a detection acoustic barrier on the connection lines between each sound source and receiver. When a target crosses the acoustic barrier, the forward acoustic scattering effect of the target body and the excited source-induced internal waves will cause continuous variation of the received sound field. Appropriate detection algorithms can be used to extract the time when the target crosses the acoustic barrier, but it is not sufficient to estimate the target's speed, heading and other states. Existing methods have many restrictions on the target prior information and system configuration, and face problems such as insufficient estimation accuracy and sensor quantity limitation in practical applications; there is a method that assumes the target speed is known and uses multiple acoustic barriers to obtain the target distance estimation result, but it is difficult to obtain the target speed information in practical applications; there is also a method that uses the time delay difference and geometric relationship between the transmitting and receiving connection lines of a bistatic system to perform projection ranging, but it fails when the target crosses the intersection point of the acoustic barrier, and the application scenario is limited to bistatic systems.

[0003] Therefore, it is necessary to improve one or more problems existing in the above related technical solutions.

[0004] It should be noted that this part aims to provide background or context for the technical solutions of the present disclosure stated in the claims. The descriptions herein are not admitted to be prior art because they are included in this part. Summary of the Invention

[0005] The purpose of the embodiments of the present disclosure is to provide a method for evaluating the motion state of an underwater target based on a distributed acoustic barrier system, thereby at least to some extent overcoming one or more problems caused by the limitations and defects of related technologies.

[0006] According to the first aspect of the embodiments of the present disclosure, a method for evaluating the motion state of an underwater target based on a distributed acoustic barrier system is provided. The method includes:

[0007] Deploy a distributed acoustic barrier system and establish a distributed acoustic barrier and target motion model; wherein, the distributed acoustic barrier system includes M sound sources and N receivers, and M×N acoustic barriers are formed between each sound source and receiver;

[0008] Construct a parameter estimation linear equation set according to the target parameters of the target to be estimated in the distributed acoustic barrier and target motion model;

[0009] Use the least squares algorithm to solve the parameter estimation linear equation set to obtain the target parameter estimation result;

[0010] According to the target parameter estimation results, the speed, navigation angle, and position and distance estimation of the target when crossing each sound barrier are obtained.

[0011] Furthermore, the steps of deploying a distributed sound barrier system and establishing a distributed sound barrier and target motion model include:

[0012] Number the sound sources and receivers starting from 1 according to their quantity; where M×N≥4;

[0013] With sound source No. 1 as the origin and the horizontal line between sound source No. 1 and receiver No. 1 as the x-axis, a plane rectangular coordinate system is established;

[0014] Establish the straight line equations of each sound barrier and the target uniform linear motion equation;

[0015] According to the straight line equation of each sound barrier and the target uniform straight line motion equation, the distributed sound barrier and target motion models are jointly constructed.

[0016] Furthermore, the linear equation of each sound barrier is expressed as:

[0017]

[0018] in, is the first coefficient, is the second coefficient, is the third coefficient; and , is the position of each sound source, is the location of each receiver;

[0019] The expression of the target uniform linear motion equation is:

[0020]

[0021] in, The target to be estimated at the reference time The location where the first sound barrier is crossed, For the moment The target position to be estimated, is the horizontal velocity of the target to be estimated, is the vertical velocity of the target to be estimated, is the speed of the target to be estimated, is the navigation angle of the target to be estimated;

[0022] The expression of the distributed sound barrier and target motion model is:

[0023]

[0024] in, is the time when the target to be estimated passes through each sound barrier.

[0025] Furthermore, in the step of constructing a linear equation system for parameter estimation according to the target parameters of the target to be estimated in the distributed sound barrier and the target motion model, it includes:

[0026] According to the abscissa and ordinate of the position where the target to be estimated passes through the first sound barrier, the target motion speed, the speed of the target to be estimated, and the navigation angle of the target to be estimated, the target parameters to be estimated are constituted;

[0027] Construct a linear equation system for parameter estimation according to the target parameters to be estimated.

[0028] Furthermore, in the step of using the least squares algorithm to solve the linear equation system for parameter estimation to obtain the target parameter estimation result, it includes:

[0029] Use the detection algorithm to obtain the time when the target passes through each sound barrier;

[0030] Substitute the time when the target passes through each sound barrier into the linear equation system for parameter estimation and solve based on the least squares method to obtain the target parameter estimation result.

[0031] Furthermore, the expression of the target parameter estimation result is:

[0032]

[0033] Among them, is the coefficient matrix, is the parameter to be estimated, is the constant vector.

[0034] Furthermore, in the step of obtaining the speed, navigation angle of the target to be estimated, and the position and distance estimation when passing through each sound barrier according to the target parameter estimation result, it includes:

[0035] According to the target parameter estimation result, obtain the speed of the target to be estimated and the navigation angle of the target to be estimated;

[0036] According to the speed of the target to be estimated and the navigation angle of the target to be estimated, obtain the position and distance estimation when passing through each sound barrier.

[0037] Furthermore, the expression of the speed of the target to be estimated is:

[0038]

[0039] The expression of the navigation angle of the target to be estimated is:

[0040]

[0041] The expression for the position when passing through each sound barrier is:

[0042]

[0043] The expression for the estimated distance from the origin when passing through each sound barrier is:

[0044]

[0045] Where is the origin position.

[0046] The technical solutions provided by the embodiments of the present disclosure may include the following beneficial effects:

[0047] In the embodiments of the present disclosure, through the above-mentioned underwater target motion state evaluation method based on a distributed sound barrier system, on the one hand, taking the two-dimensional coordinates of the target's first crossing of the sound barrier, the target speed, and the navigation angle as the parameters to be estimated, the parameter estimation problem is transformed into a linear equation system solving problem; substituting the time delay difference of the target crossing the sound barrier into the equation to solve the target motion state estimation, and further calculating the distance between the target and the sound source when passing through each sound barrier. On the other hand, under the minimum standard that the product of the number of sound sources and receivers is not less than 4, this method can be used for any sound transmission system composed of multiple sound sources and receivers, with stronger versatility and accurate and reliable state estimation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0049] Figure 1 A step diagram showing a method for evaluating the motion state of an underwater target based on a distributed sound barrier system in an exemplary embodiment of the present disclosure;

[0050] Figure 2 A specific flowchart showing a method for evaluating the motion state of an underwater target based on a distributed sound barrier system in an exemplary embodiment of the present disclosure;

[0051] Figure 3 A schematic diagram showing the situation of the target crossing in Scenario 1 in an exemplary embodiment of the present disclosure;

[0052] Figure 4 A schematic diagram showing the situation of the target crossing in Scenario 2 in an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The features, structures, or characteristics described may be combined in any suitable manner in one or more embodiments.

[0054] In addition, the accompanying drawings are only schematic illustrations of the embodiments of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus repeated descriptions thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0055] In this example embodiment, a method for evaluating the motion state of an underwater target based on a distributed sound barrier system is provided. Referring to Figure 1 as shown, the method for evaluating the motion state of an underwater target based on a distributed sound barrier system may include: Step S101 to Step S104.

[0056] Step S101: Deploy a distributed sound barrier system and establish a distributed sound barrier and target motion model; wherein, the distributed sound barrier system includes M sound sources and N receivers, and M×N sound barriers are formed between each sound source and the receivers;

[0057] Step S102: Construct a parameter estimation linear equation system according to the target parameters of the target to be estimated in the distributed sound barrier and target motion model;

[0058] Step S103: Solve the parameter estimation linear equation system by using the least squares algorithm to obtain the target parameter estimation result;

[0059] Step S104: Obtain the speed, navigation angle of the target to be estimated, and the position and distance estimations when passing through each sound barrier according to the target parameter estimation result.

[0060] Through the above method for evaluating the motion state of an underwater target based on a distributed sound barrier system, on the one hand, taking the two-dimensional coordinates of the target's first crossing of the sound barrier, the target speed, and the navigation angle as the parameters to be estimated, the parameter estimation problem is transformed into a linear equation system solving problem; substituting the time delay difference of the target crossing the sound barrier into the equation, solving the target motion state estimation, and further calculating the distance between the target and the sound source when passing through each sound barrier. On the other hand, under the minimum standard that the product of the number of sound sources and receivers is not less than 4, this method can be used for any sound transmission system composed of multiple sound sources and receivers, with stronger versatility and accurate and reliable state estimation results.

[0061] Next, referring to Figures 1 to 4A more detailed description of each step of the above underwater target motion state evaluation method based on a distributed sound barrier system in this exemplary embodiment is provided.

[0062] In step S101, as Figure 2 shown, it is a specific flowchart of the underwater target motion state evaluation method based on a distributed sound barrier system. A distributed sound barrier system is deployed, and a distributed sound barrier and target motion model is established; wherein, the distributed sound barrier system includes M sound sources and N receivers, and M×N sound barriers are formed between each sound source and receiver.

[0063] Specifically, the system consists of M sound sources and N receivers with separate transmitting and receiving. Each sound source consists of P transducers (P≥1), and each receiver consists of a hydrophone array with Q elements (Q≥1). The product of the number of sound sources and receivers is not less than 4 (M×N≥4). The sound sources and receivers are numbered starting from 1 according to their quantities. Each sound source radiates detection pulses with non-overlapping frequency bands (common signal forms such as linear frequency modulation and hyperbolic frequency modulation are acceptable). Each receiver continuously collects the transmitted signals of each sound source, and M×N sound barriers are formed between each sound source and receiver.

[0064] Using the above system configuration, a mathematical equation for the distributed sound barrier and target motion model is established:

[0065] First step: Taking the 1st sound source as the origin and the horizontal connection line between the 1st sound source and the 1st receiver as the positive x-axis direction, a plane rectangular coordinate system is established. The positions of each sound source node are represented by where represents the sound source, and the subscripts respectively represent the horizontal and vertical coordinates, and m is the sound source serial number with a value range of 1 to M; the positions of each receiver node are represented by where represents the sound source, and n is the receiver serial number with a value range of 1 to N. The sound barrier between each sound source and receiver can be represented as a straight line, and its equation is:

[0066]

[0067] where represents the sound barrier serial number between the mth sound source and the nth receiver, and the equation coefficients are:

[0068]

[0069] Second step: When the target sails in a straight line at a constant speed, its motion equation is:

[0070]

[0071] where For the target at the reference time The location where the first sound barrier is crossed, and For the moment The target location, and are the horizontal and vertical velocities of the target, respectively. is the target speed, is the target heading (defined as the target navigation direction vector and The model can also be used for non-uniform linear motion targets, but there will be errors.

[0072] Target in time Crossing the sound barrier , the target track intersects with the sound barrier, and the sound barrier equation and the target motion equation are combined to get:

[0073]

[0074] In step S102 and step S103, if Figure 2 As shown, according to the target parameters of the target to be estimated in the distributed sound barrier and the target motion model, a parameter estimation linear equation group is constructed; the parameter estimation linear equation group is solved using the least squares algorithm to obtain the target parameter estimation result.

[0075] Specifically, the target parameter to be estimated is defined as the variable to be measured, a linear equation system for parameter estimation is constructed, and the system is solved based on the least squares algorithm.

[0076] Step 1: The target parameters to be estimated include , , , There are 4 parameters in total, which are the horizontal and vertical coordinates of the position where the target crosses the first sound barrier, the target movement speed, and the target navigation angle. Therefore, the target parameter estimation problem is transformed into a linear equation system solution problem. The above problems are organized as follows:

[0077]

[0078] in is the coefficient matrix, is the parameter to be estimated, is a constant vector, and the three are:

[0079]

[0080] in for The coefficient sub-matrix of for The coefficient sub-vector, and the elements of each row are respectively composed of the geometric coefficients of the sound barrier equation formed by the sound source and each receiver. .

[0081] Step 2: Based on a suitable detection algorithm, obtain the moments when the target passes through each sound barrier , substitute them into the linear equation system and solve based on the least squares method. The target parameter estimation results are as follows:

[0082]

[0083] In step S104, as Figure 2 shown, according to the target parameter estimation results, the speed, navigation angle of the target to be estimated, and the position and distance estimations when passing through each sound barrier are obtained.

[0084] Specifically, based on the parameter estimation results, calculate the target speed and navigation angle. The target speed is , and the navigation angle is . Therefore, the positions where the target passes through the other three sound barriers can be estimated as:

[0085]

[0086] Based on the target passing positions, the distance estimations from the origin are:

[0087]

[0088] In a specific embodiment, referring to Figure 3 and Figure 4 shown, an application example is given. A bistatic underwater target detection system with two transmitters and two receivers is simulated, including two sound sources and two receivers, and each sound source and receiver consists of a transducer. Taking the No. 1 sound source as the origin and the line connecting the No. 1 sound source and the No. 1 receiver as the positive x-axis, a plane rectangular coordinate system is established, with the unit being meters (unless otherwise marked, the subsequent coordinate unit is meters). The coordinates of the No. 1 and No. 2 sound sources are respectively and , and the coordinates of the No. 1 and No. 2 receivers are respectively and . The sound source emits a linear frequency modulated pulse with a center frequency of 50 kHz, a bandwidth of 5 kHz, and a pulse width of 0.2 s at a period of 0.5 s. The receiver continuously collects and processes the high-frequency detection pulses from the sound source, and a total of 4 sound barriers are formed between each transmitter and receiver . The initial position of the target is set at , and it moves along at a speed of Moving in a uniform straight line in a certain direction, it passed through four sound barriers in sequence. Each time it passed through a sound barrier, the receiver output a target crossing time through a built-in detection algorithm. Using the system node positions and the four target crossing times to solve the coefficient matrix , the position estimation of the target crossing Barrier 1, and the target speed in the and direction projections, and further obtaining the intersection points of the target with the other three sound barriers.

[0089] When the target crosses the detection area at a uniform speed with a heading angle, the detection nodes, sound barriers, and target track are as shown in Figure 3 . The actual speed and angle of the target are marked in the upper right corner of Figure 4 . Below it are the results of the target crossing the sound barrier, target state estimation, and crossing position estimation obtained by detection. It can be seen that the times for crossing the sound barriers are 7 s, 11.5 s, 22 s, and 27 s respectively. Substituting these times into the equations for solution, the estimated results of the target speed and angle are 7.87 m / s and 72.39° respectively. Using and to represent the relative errors of speed and heading angle estimation, where and are the estimated and true values of the navigation speed respectively, and are the estimated and true values of the navigation angle respectively, and the errors are 1.9% and 6.4% respectively.

[0090] When the target crosses the detection area at a uniform speed with an 88° heading angle, the detection nodes, sound barriers, and target track are as shown in Figure 2 . The times for the target to cross the 4 sound barriers are 6.5 s, 10.5 s, 22 s, and 26 s respectively. Substituting them into the linear equations for solution, the estimated results of the target speed and angle are 7.87 m / s and 72.39° respectively, and the errors are 0.4% and 2.2% respectively.

[0091] This application has achieved obvious implementation effects in typical embodiments. The method for estimating the target motion state based on distributed sound barriers has little limitation on the system layout and sensor configuration, has good generality and robustness, can be used for target early warning and defense in important areas such as ports and main roads, and has broad application prospects.

[0092] Through the above method for evaluating the motion state of an underwater target based on a distributed sound barrier system, a distributed sound barrier system is composed of no less than 4 transceiver nodes. After obtaining the time for the target to cross each sound barrier by using an appropriate detection method, the motion speed, navigation angle, and distance of the target passing between the transceivers can be accurately estimated. This method establishes a linear equation system based on the positions of the detection nodes and the target motion model, with the two-dimensional coordinates of the target's first crossing of the sound barrier, the target speed, and the navigation angle as the parameters to be estimated, and transforms the parameter estimation problem into a problem of solving a linear equation system; substitutes the time delay difference of the target crossing the sound barrier into the equation to solve the estimation of the target motion state, and further calculates the distance between the target and the sound source when crossing each sound barrier. Under the minimum standard that the product of the number of sound sources and receivers is not less than 4, the method can be used for a sound transmission system composed of any number of sound sources and receivers, with stronger versatility and accurate and reliable state estimation results.

[0093] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0094] After considering the specification and practicing the invention disclosed herein, those skilled in the art will readily conceive of other embodiments of the present disclosure. This application is intended to cover any variations, uses, or adaptations of the present disclosure, which follow the general principles of the present disclosure and include the common general knowledge or conventional technical means in the technical field not disclosed in the present disclosure. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present disclosure are pointed out by the appended claims.

Claims

1. A method for evaluating the motion state of an underwater target based on a distributed sound barrier system, characterized in that: The method includes: Deploy a distributed sound barrier system and establish a distributed sound barrier and target motion model; wherein the distributed sound barrier system includes M sound sources and N receivers, and M×N sound barriers are formed between each sound source and receiver; According to the target parameters of the target to be estimated in the distributed sound barrier and the target motion model, a parameter estimation linear equation group is constructed; The least squares algorithm is used to solve the parameter estimation linear equations to obtain the target parameter estimation results; According to the target parameter estimation results, the speed, navigation angle, and position and distance estimation of the target when crossing each sound barrier are obtained; The steps of deploying a distributed sound barrier system and establishing a distributed sound barrier and target motion model include: Number the sound sources and receivers starting from 1 according to their quantity; where M×N≥4; With sound source No. 1 as the origin and the horizontal line between sound source No. 1 and receiver No. 1 as the x-axis, a plane rectangular coordinate system is established; Establish the straight line equations of each sound barrier and the target uniform linear motion equation; According to the straight line equation of each sound barrier and the target uniform straight line motion equation, the distributed sound barrier and target motion models are jointly constructed.

2. According to claim 1, the method for evaluating the motion state of underwater targets based on a distributed sound barrier system is characterized in that: The expression of the straight line equation of each sound barrier is: in, is the first coefficient, is the second coefficient, is the third coefficient; and , is the position of each sound source, is the location of each receiver; The expression of the target uniform linear motion equation is: in, The target to be estimated at the reference time The location where the first sound barrier is crossed, For the moment The target position to be estimated, is the horizontal velocity of the target to be estimated, is the vertical velocity of the target to be estimated, is the speed of the target to be estimated, is the navigation angle of the target to be estimated; The expression of the distributed sound barrier and target motion model is: in, is the time when the target is estimated to pass through each sound barrier.

3. According to claim 2, the method for evaluating the motion state of underwater targets based on a distributed sound barrier system is characterized in that: The step of constructing a parameter estimation linear equation group according to the target parameters of the target to be estimated in the distributed sound barrier and the target motion model includes: The parameters of the target to be estimated are formed according to the horizontal and vertical coordinates of the position where the target to be estimated crosses the first sound barrier, the target movement speed, the speed of the target to be estimated and the navigation angle of the target to be estimated; Construct a parameter estimation linear equation system based on the target parameters to be estimated.

4. According to claim 3, the method for evaluating the motion state of underwater targets based on a distributed sound barrier system is characterized in that: The steps of solving the parameter estimation linear equations using the least squares algorithm to obtain the target parameter estimation results include: Use detection algorithms to obtain the moment when the target passes through each sound barrier; The time when the target passes through each sound barrier is substituted into the parameter estimation linear equation group and solved based on the least squares method to obtain the target parameter estimation result.

5. According to claim 3, the method for evaluating the motion state of underwater targets based on a distributed sound barrier system is characterized in that: The expression of the target parameter estimation result is: in, is the coefficient matrix, is the parameter to be estimated, is a constant vector.

6. The underwater target motion state assessment method based on the distributed sound barrier system according to claim 5 is characterized in that: The step of obtaining the speed, navigation angle, position and distance of the target to be estimated when crossing each sound barrier according to the target parameter estimation result includes: According to the target parameter estimation result, the speed of the target to be estimated and the navigation angle of the target to be estimated are obtained; According to the speed of the target to be estimated and the navigation angle of the target to be estimated, the position and distance estimation when crossing each sound barrier are obtained.

7. The underwater target motion state assessment method based on a distributed sound barrier system according to claim 6 is characterized in that: The expression of the target speed to be estimated is: The expression of the navigation angle of the target to be estimated is: The expression of the position when passing through each sound barrier is: The expression for estimating the distance from the origin when crossing each sound barrier is: in, is the origin position.

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