An underwater target detection situation simulation method and system in UUV cooperative operation

Abstract

The application provides a kind of underwater target detection situation simulation method and system in UUV cooperative operation, belong to underwater target detection simulation field.For solving the difficulty of capturing mobile non-cooperative underwater target, and the detection range of single base sonar is small, and it is difficult to capture, and it is easy to be found by target.The application realizes the whole process of underwater target detection real-time demonstration system simulation of non-cooperative underwater target movement-sonar array configuration-judgment whether non-cooperative underwater target can be captured, calculates the probability of whether non-cooperative underwater target can be captured through simulation, provides data support for actual capture of non-cooperative underwater target, so as to adjust the capture simulation and improve the capture efficiency;Using double base sonar instead of single base sonar, its position is generally not easy to be found by enemy, reduces the probability of base being found and captured;And the detection radius of double base is more than ten times of single base detection radius, which can effectively improve the detection effect.

Description

Technical Field

[0001] This invention relates to the field of underwater target detection simulation technology, and more specifically, to a method and system for simulating the underwater target detection situation in UUV collaborative operations. Background Technology

[0002] Non-cooperative targets attempt to enter our specific sea areas, where multiple UUV cooperative operation systems are deployed. These systems can identify and capture the movement trajectories of non-cooperative targets, preventing them from interfering with our waters. The layout and structure of the UUV cooperative operation system affects important indicators such as the detection range and defense probability of the entire system, and the layout design for UUV cooperative operation is complex.

[0003] UUV collaborative operations can combine UUVs with different functions to meet diverse needs for marine development, detection, and protection. Furthermore, forming an array of multiple UUVs can improve detection accuracy and enable the entire system to achieve more diverse functions. Given the inherent complexity of UUV collaboration, reasonable simulation of the collaborative operation situation is crucial. This can effectively reduce unnecessary design flaws and accelerate the development of UUV collaborative operation systems, which is the significant meaning of the simulation in this invention. Summary of the Invention

[0004] The technical problem to be solved by this invention is:

[0005] To address the issue of how to conduct effective UUV cooperative operations, thereby reducing unnecessary layout design and increasing the probability of capturing non-cooperative underwater targets.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] This invention provides a method for simulating the underwater target detection situation in UUV collaborative operations, comprising the following steps:

[0008] Step 1: Set simulation parameters. The simulation parameters include the outer warning line radius, the inner warning line radius, the detection radius of the UUV for Class A non-cooperative underwater targets, the detection radius of the UUV for Class B non-cooperative underwater targets, the detection radius of the UUV for Class A, Class B, and Class C non-cooperative underwater targets, the movement speed of the UUV, the movement speed of Class A, Class B, and Class C non-cooperative underwater targets, the number configuration of non-cooperative underwater targets, the number of Monte Carlo simulations, the patrol mode of the UUV, the island radius, the basic detection probability, and the increased probability.

[0009] Step 2: Select the non-cooperative underwater target motion mode, which is divided into a straight-line motion mode and a DWA path planning motion mode.

[0010] Step 3: Based on the defense probability indicators of the inner and outer warning lines, construct the formation of the UUVs;

[0011] Step 4: To verify whether the array configuration can meet the requirements, a Monte Carlo test is used to make different types of non-cooperative underwater targets move towards the target position from different directions each time.

[0012] Step 5: Calculate the state of the non-cooperative underwater target, UUV, and transmitting sonar at each simulation moment. The state refers to the horizontal axis, vertical axis, heading angle, velocity, and angular velocity.

[0013] Step 6: Based on the criteria for determining whether different types of non-cooperative underwater targets can be captured, make a judgment for each non-cooperative underwater target at each simulation time.

[0014] Step 7: When all non-cooperative underwater targets in this experiment stop moving, the experiment ends. Then, determine whether the number of experiments is greater than the set number of experiments. If it is greater, the experiment ends. If it is less, repeat steps 4 to 6 until the experiment ends. Calculate and display the defense probability of the inner and outer warning lines.

[0015] Furthermore, in step two, when the non-cooperative underwater target's motion mode is a straight-line motion mode, the straight-line motion model is:

[0016] X new =F×X old +B×u

[0017]

[0018]

[0019] Where X = (x, y, yaw, v, ω) T X represents the motion state of the target. new X represents the current motion state of the target. old The x-coordinate represents the target's position at the previous moment, the y-coordinate represents the target's position, the yaw-angle represents the target's heading angle, the v-velocity represents the target's velocity, and the ω-velocity represents the target's angular velocity; dt represents the time interval; u = (v, ω). T It represents the velocity and angular velocity at the current moment.

[0020] Furthermore, in step two, when the non-cooperative underwater target motion mode is the DWA path planning motion mode, a sampling velocity space that satisfies the hardware constraints of the mobile robot is determined in the velocity space (v,ω) based on the current position and velocity state of the mobile robot. Then, the trajectory of the mobile robot moving for a certain period of time under these velocity conditions is calculated, and the trajectory is evaluated by the evaluation function. Finally, the velocity corresponding to the trajectory with the best evaluation is selected as the mobile robot's motion speed. This process is repeated until the mobile robot reaches the target point.

[0021] Furthermore, it includes the following steps:

[0022] S1. Sample the speed of the mobile robot.

[0023] Under velocity boundary constraints, the sampleable velocity space V is as follows. m for,

[0024] V m ={(v, ω)|v∈[v min v max ], ω∈[ω min ω max ]}

[0025] In the formula v min v max ω represents the minimum and maximum linear velocities of the mobile robot, respectively. min ω max These are the minimum and maximum angular velocities of the mobile robot, respectively.

[0026] Under acceleration constraints, the sampleable velocity space V is as follows. d for,

[0027] V d ={(v, ω)|v∈[v c -a v max *Δt,v c +a v max *Δt],ω∈[ω c -a ωmax *Δt,ω c +a ωmax *Δt]}

[0028] In the formula v c ω c These are the linear velocity and angular velocity of the mobile robot at the current moment, a. v max a ωmax These are the maximum linear acceleration and maximum angular acceleration of the mobile robot, respectively, and Δt is the time difference between the current moment and the previous moment of the mobile robot.

[0029] Under the constraint of environmental obstacles, the sampleable velocity space V is as follows. a for,

[0030]

[0031] In the formula, dist(v, ω) represents the shortest distance between the simulated trajectory of the mobile robot and the obstacle at the current speed, v min Let ω be the minimum linear velocity of the mobile robot. min This represents the minimum angular velocity of the mobile robot.

[0032] Combining the three types of speed constraints mentioned above, the final mobile robot speed sampling space V s It is the intersection of three velocity spaces, that is,

[0033] V s =V m ∩V d ∩V a

[0034] S2. Perform trajectory prediction for the mobile robot. In trajectory prediction, determine the velocity sampling space V. s Then, the DWA algorithm samples the space uniformly at a certain sampling interval. After sampling a set of (v, ω), the trajectory is predicted, i.e., the position is updated, through the kinematic model of the mobile robot.

[0035] S3. Evaluate the trajectory of the mobile robot. In the trajectory evaluation, multiple sets of sampled trajectories need to be evaluated and the best one is selected. The optimal trajectory is selected by comparing scores through standard evaluation trajectories, and then the speed corresponding to the optimal trajectory is selected as the driving speed.

[0036] Furthermore, the evaluation function for assessing each trajectory is:

[0037] G(v,ω)=σ(α·heading(v,ω))+σ(β·dist(v,ω))+σ(γ·velocity(v,ω))

[0038] Where heading(v, ω) is the azimuth evaluation function, i.e., heading(v, ω) = π - Δθ, where Δθ is the error of the angle between the direction of the trajectory endpoint and the line connecting the target point at the current sampling speed; dist(v, ω) is the distance evaluation function, representing the shortest distance between the simulated trajectory and the obstacle at the current speed; velocity(v, ω) is the velocity evaluation function, representing the current speed, which can be directly represented by the current linear velocity; the larger the current linear velocity, the faster the speed on the planned trajectory, and the higher the evaluation score; α, β, and γ are all coefficients of the evaluation function; σ represents normalization.

[0039] Furthermore, in step three, under bistatic conditions, the sound source, target, and receiver form a triangular relationship, and the detection range of the sonar is an ellipse.

[0040] Furthermore, considering only noise limitations, the equations for bistatic sonar are:

[0041] TL1+TL2=SL-NL+DI-DT+TS

[0042] In the formula, TL1 and TL2 are the propagation losses from the sound source to the target and from the target to the receiver, respectively; SL is the sound source level; TS is the target intensity; NL is the ship's self-noise and ambient noise levels received by the receiving hydrophone array; DI is the directivity index of the receiving hydrophone array; DT is the detection threshold; and the noise masking level is NL-DI+DT.

[0043] When the system parameters of the sonar system and the sea state are determined, the sound source level and noise masking level are fixed values; while TS, TL1, and TL2 vary with the geometric relationship between the target and the bistatic sonar.

[0044] (1) Regarding the value of TS: Under bistatic conditions, TS depends on two quantities: the incident angle and the angle of repose of the sound wave; by statistically averaging the TS values ​​of each incident angle and angle of repose under bistatic conditions according to certain rules, we obtain... by Instead of using the random TS for range estimation, the final sonar coverage area is a regularly shaped ellipse;

[0045] (2) Regarding propagation loss and effective range: the distance r between TL1 and the transmitter and target T Related, denoted as TL1(r) T Similarly, TL2 and the distance r from the target to the receiver are also related. R Related, denoted as TL2(r) R Given that SL, NL, TS, DI, and DT are all determined, the equations for bistatic sonar are:

[0046] TL1(r T )+TL2(r R ) = SL - NL + DI - DT + TS = constant

[0047] If the sound wave propagation loss is calculated based on spherical wave attenuation and absorption attenuation is ignored, then:

[0048] TL=20lgr

[0049] Substituting into the bistatic sonar equations, we get:

[0050] 20lgr T +20lgr R=TS+SL-(NL-DI)-DT

[0051] Further derivation can obtain:

[0052]

[0053] (3) For the detection range and detection area, define the distance between the sound source and the receiver as D, and the equivalent radius of the bistatic system is When D=0, the detection range of the bistatic system is a circle with radius R; as the parameter D increases, when 0<D<1.41R, the detection range of the bistatic sonar system gradually evolves from a circle to an approximate ellipse; when D gradually exceeds 1.41R, the detection range of the bistatic sonar gradually distorts from the ellipse; when D further increases to 2R, the detection range of the bistatic sonar system will be divided into two mutually disjoint regions;

[0054] Therefore, 0<D<1.41R is defined as the optimal distance between the sound source level and the receiver for bistatic sonar, and at this time the detection range of the bistatic sonar system can be regarded as an ellipse.

[0055] Further, through Monte Carlo tests, the number of UUVs required to achieve different probabilities for different types of non-cooperative underwater targets under different deployment radii can be calculated. Specifically, when the deployment radius is fixed, the number of UUVs required for Class A non-cooperative underwater targets, Class B non-cooperative underwater targets and Class C non-cooperative underwater targets under different probabilities can be calculated.

[0056] The underwater target detection situation simulation method in UUV cooperative operation according to claim 8, characterized in that: in step six, the judgment criterion for whether different types of non-cooperative underwater targets are captured is whether they stop moving. When a non-cooperative underwater target is captured, it stops moving; when the non-cooperative underwater target is not captured, it continues to move toward the target. If the non-cooperative underwater target has not been captured all the time, it stops moving when the distance between it and the target is less than 3.

[0057] An underwater target detection situation simulation system in UUV cooperative operation, the system has program modules corresponding to the above steps, and executes the steps in the above underwater target detection situation simulation method in UUV cooperative operation when running.

[0058] Compared with the prior art, the beneficial effects of the present invention are:

[0059] This invention discloses a method and system for simulating the underwater target detection situation in UUV collaborative operations. It uses a computer to simulate the layout of UUV collaborative operations and performs situational simulation of the entire process. Simultaneously, it analyzes the effectiveness of the entire simulation process using indicators such as detection error and defense probability, playing a crucial role in exploring reasonable UUV collaborative operation methods. The simulation process effectively accelerates the design of UUV collaborative operation systems, realizing a real-time demonstration system simulation of the entire underwater target detection process, from "non-cooperative underwater target movement - sonar array configuration - judgment of whether non-cooperative underwater targets can be captured." The simulation calculates the probability of capturing non-cooperative underwater targets, providing data support for actual capture of non-cooperative underwater targets, facilitating adjustments to the capture simulation and improving capture efficiency.

[0060] Using bistatic sonar instead of monostatic sonar, where the transmitter and receiver are separated by a certain distance and the receiver only operates by listening, the location is generally not easy for the enemy to detect, reducing the probability of the base being discovered and captured; moreover, the detection radius of bistatic sonar is more than ten times that of monostatic sonar, which can effectively improve the detection effect. Attached Figure Description

[0061] Figure 1 This is a flowchart of a method for simulating the underwater target detection situation in UUV collaborative operations according to the present invention;

[0062] Figure 2 The geometric relationship between the bistatic sound source, target, and receiver in this invention. Figure 1 ;

[0063] Figure 3 The geometric relationship between the bistatic sound source, target, and receiver in this invention. Figure 2 ;

[0064] Figure 4 This is a chart showing the number of UUVs required to achieve different defense probabilities for a type A non-cooperative underwater target in this embodiment of the invention.

[0065] Figure 5 This is a chart showing the number of UUVs required to achieve different defense probabilities for Class B non-cooperative underwater targets in this embodiment of the invention.

[0066] Figure 6 This is a chart showing the number of UUVs required to achieve different defense probabilities for Class C non-cooperative underwater targets in this embodiment of the invention.

[0067] Figure 7 This is a screenshot of the situation simulation GUI. Detailed Implementation

[0068] In the description of this invention, it should be noted that the terms used in the various embodiments, such as "upper," "lower," "front," "rear," "left," and "right," which indicate orientation, are only used to simplify the description of the positional relationships based on the accompanying drawings and do not mean that the components and devices referred to must be operated in accordance with the specific orientations and defined operations, methods, and structures in the specification. Such directional terms do not constitute a limitation of this invention.

[0069] In the description of this invention, it should be noted that the terms "first," "second," and "third" mentioned in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," and "third" may explicitly or implicitly include one or more of that feature.

[0070] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0071] Specific Implementation Plan 1: Combining Figures 1 to 7 As shown, this invention provides a method for simulating the underwater target detection situation in UUV collaborative operations, comprising the following steps:

[0072] Step 1: Set simulation parameters, including: outer warning line radius, inner warning line radius, UUV detection radius for Class A non-cooperative underwater targets, UUV detection radius for Class B non-cooperative underwater targets, UUV detection radius for Class C non-cooperative underwater targets, detection radius of Class A, B, and C non-cooperative underwater targets for UUV respectively, UUV's movement speed, movement speed of Class A, B, and C non-cooperative underwater targets, number configuration of non-cooperative underwater targets, Monte Carlo simulation, UUV patrol mode, island radius, basic detection probability, and increased probability;

[0073] Among them, non-cooperative underwater targets of categories A, B and C are classified according to the size and speed of the enemy target. Category A non-cooperative underwater targets are the largest and fastest targets, Category B non-cooperative underwater targets are in the middle, and Category C non-cooperative underwater targets are the smallest and slowest targets.

[0074] Step 2: Select the non-cooperative underwater target motion mode, which is divided into linear motion and DWA path planning motion.

[0075] The linear motion model is as follows:

[0076] X new =F×X old +B×u

[0077]

[0078]

[0079] Where X = (x, y, yaw, v, ω) T X represents the motion state of the target. new X represents the current motion state of the target. old The x-coordinate represents the target's position at the previous moment, the y-coordinate represents the target's position, the yaw-angle represents the target's heading angle, the v-velocity represents the target's velocity, and the ω-velocity represents the target's angular velocity; dt represents the time interval; u = (v, ω) T Represents the velocity and angular velocity at the current moment;

[0080] The core idea of ​​the DWA path planning algorithm is to determine a sampled velocity space in the velocity space (v, ω) that satisfies the hardware constraints of the mobile robot based on its current position and velocity state. Then, it calculates the trajectory of the mobile robot moving within a certain time under these velocities, evaluates the trajectory using an evaluation function, and finally selects the velocity corresponding to the trajectory with the best evaluation as the mobile robot's movement speed. This process is repeated until the mobile robot reaches the target point. Here, the mobile robot refers to a non-cooperative underwater target, and its movement trajectory is obtained by simulating the mobile robot's movement trajectory.

[0081] Includes the following steps:

[0082] S1. Velocity sampling is performed on the mobile robot. Due to limitations imposed by the mobile robot's hardware, structure, and environment, the velocity sampling space (v, ω) is subject to certain range constraints. These constraints include velocity boundary limitations, acceleration limitations, and environmental obstacle limitations.

[0083] Under velocity boundary constraints, the sampleable velocity space V is as follows. m for,

[0084] V m ={(v, ω)|v∈[v min v max ], ω∈[ω min ω max ]}

[0085] In the formula v min v max ω represents the minimum and maximum linear velocities of the mobile robot, respectively. min ω max These are the minimum and maximum angular velocities of the mobile robot, respectively.

[0086] Under acceleration constraints, the sampleable velocity space V is as follows. d for,

[0087] V d ={(v, ω)|v∈[v c -a v max *Δt,v c +a v max *Δt],ω∈[ω c -a ωmax *Δt,ω c +a ωmax *Δt]}

[0088] In the formula v c ω c These are the linear velocity and angular velocity of the mobile robot at the current moment, a. v max a ωmax These are the maximum linear acceleration and maximum angular acceleration of the mobile robot, respectively, and Δt is the time difference between the current moment and the previous moment of the mobile robot.

[0089] Under the constraint of environmental obstacles, the sampleable velocity space V is as follows. a for,

[0090]

[0091] In the formula, dist(v, ω) represents the shortest distance between the simulated trajectory of the mobile robot and the obstacle at the current speed. In the absence of obstacles, dist(v, ω) will be a large constant value. min Let ω be the minimum linear velocity of the mobile robot. min This represents the minimum angular velocity of the mobile robot.

[0092] Combining the three types of speed constraints mentioned above, the final mobile robot speed sampling space V s It is the intersection of three velocity spaces, that is,

[0093] V s =V m ∩V d ∩V a

[0094] S2. Perform trajectory prediction for the mobile robot. In trajectory prediction, determine the velocity sampling space V. s Then, the DWA algorithm samples uniformly in the space at a certain sampling interval (resolution). After sampling a set of (v, ω), the trajectory is predicted, i.e., the position is updated, through the kinematic model of the mobile robot.

[0095] S3. Evaluate the trajectory of the mobile robot. In trajectory evaluation, multiple sampled trajectories need to be evaluated and the best one selected. The optimal trajectory is chosen by comparing scores against a standard evaluation trajectory, and then the speed corresponding to the optimal trajectory is selected as the driving speed. The evaluation function for each trajectory is as follows:

[0096] G(v,ω)=σ(α·heading(v,ω))+σ(β·dist(v,ω))+σ(γ·velocity(v,ω))

[0097] Here, heading(v, ω) is the azimuth evaluation function, used to evaluate the error Δθ of the angle between the direction of the trajectory endpoint and the line connecting the target point at the current sampling speed. Since we want a larger evaluation function to indicate better performance, we use π - Δθ in the evaluation, i.e., heading(v, ω) = π - Δθ; dist(v, ω) is the distance evaluation function, representing the closest distance between the simulated trajectory and the obstacle at the current speed. If there is no obstacle or the closest distance is greater than the set threshold, then its value is set to a large constant value; velocity(v, ω) is the velocity evaluation function, representing the current speed, which can be directly represented by the current linear velocity; the larger the current linear velocity, the faster the speed on the planned trajectory, and the higher the evaluation score; α, β, and γ are all coefficients of the evaluation function;

[0098] Since the local path planning process requires the collection of data from multiple sensors, the collected information cannot be continuous, which can lead to large differences in the evaluation results. Therefore, normalization (smoothing) can be performed, where σ represents normalization.

[0099] Step 3: Based on the defense probability indicators of the inner and outer warning lines, construct the formation of the UUVs;

[0100] This scheme replaces monostatic active sonar and utilizes bistatic active sonar to construct the array of UUVs, including the following steps:

[0101] Under bistatic conditions, the sound source, target, and receiver form a complex triangular relationship, the basic geometric relationship of which is as follows: Figure 2 and Figure 3 As shown, the detection range of the sonar is an ellipse;

[0102] exist Figure 2 and Figure 3 In this diagram, T represents the sound source, which can operate in transmitting mode only, emitting sound pulses into the water to illuminate the target, or it can operate in monostatic mode, simultaneously transmitting sound waves and receiving target echoes; R represents the receiver, which is located a certain distance away from the transmitter and operates only in listening mode, and its location is generally not easily detected by the enemy.

[0103] In a bistatic sonar system, the receiver R is typically composed of a UUV or an airborne dipping sonar; S represents the underwater target; r T r is the distance from the transmitter to the target. R The distance from the target to the receiver; typically, what is measured at the receiver is the sum of distances, i.e., r. ∑ =r T +r D D represents the baseline length, which, under bistatic conditions, is defined as the distance between the transmitting and receiving stations; θ T θ is the beam pointing angle measured at the sound wave transmitter. R β is the beam pointing angle; β is the split angle, defined as the angle between the lines connecting the transmitting base, the receiving base and the target with the target as the vertex.

[0104] Considering only noise limitations, the equations for bistatic sonar are:

[0105] TL1+TL2=SL-NL+DI-DT+TS

[0106] In the formula, TL1 and TL2 are the propagation losses from the sound source to the target and from the target to the receiver, respectively; SL is the sound source level; TS is the target intensity; NL is the ship's self-noise and ambient noise levels received by the receiving hydrophone array; DI is the directivity index of the receiving hydrophone array; DT is the detection threshold; and the noise masking level is NL-DI+DT.

[0107] When the system parameters of the sonar system and the sea state are determined, the sound source level and noise masking level are fixed values; while TS, TL1, and TL2 vary with the geometric relationship between the target and the bistatic sonar.

[0108] (1) Value of TS: Under bistatic conditions, TS depends on two quantities: the incident angle and the split angle. With variations in these two quantities, the intensity of a bistatic target may be less than or greater than that of a monostatic target. When estimating the range, different TS values ​​at different incident and split angles will result in different effective ranges, leading to an irregularly shaped sonar coverage area, making it impossible to calculate the detection area. Therefore, the TS values ​​for each incident and split angle under bistatic conditions are statistically averaged according to a certain rule (e.g., ±2.5°) to obtain... by Instead of using the random TS for range estimation, the final sonar coverage area is a regularly shaped ellipse, and the coverage area of ​​the ellipse is equivalent to the aforementioned irregularly shaped coverage area.

[0109] (2) Propagation loss and effective range, the distance r between TL1 and the transmitter and the target T Related, denoted as TL1(r) T); similarly, the distance r from TL2 and the target to the receiver R is related, denoted as TL2(r R ); under the condition that SL, NL, TS, DI and DT are all determined, the bistatic sonar equation is:

[0110] TL1(r T )+TL2(r R )=SL-NL+DI-DT+TS=constant

[0111] When the sound wave propagation loss is calculated according to spherical wave attenuation and absorption attenuation is ignored, then:

[0112] TL=20lgr

[0113] Substituting into the bistatic sonar equation gives:

[0114] 20lgr T +20lgr R =TS+SL-(NL-DI)-DT

[0115] Further derivation can obtain:

[0116]

[0117] (3) Detection range and detection area, define the distance between the sound source level and the receiver as D, and the equivalent radius of the bistatic system is When D=0, the detection range of the bistatic system is a circle with radius R; with the increase of parameter D, when 0<D<1.41R, the detection range of the bistatic sonar system gradually evolves from a circle to an approximate ellipse; when D gradually becomes greater than 1.41R, the detection range of the bistatic sonar gradually starts to distort from the ellipse; when D further increases to 2R, the detection range of the bistatic sonar system will be divided into two mutually non-intersecting regions; therefore, 0<D<1.41R is defined as the optimal distance between the sound source level and the receiver of the bistatic sonar, and at this time the detection range of the bistatic sonar system can be regarded as an ellipse;

[0118] Step 4: To check whether the array position configuration can meet the index, the Monte Carlo test is used to make different types of non-cooperative underwater targets move towards the target position from different directions each time;

[0119] Step 5: Calculate the states of the non-cooperative underwater target, the UUV and the transmitting sonar for each simulation moment, where the states refer to the abscissa, ordinate, heading angle, speed and angular velocity;

[0120] Through Monte Carlo experiments, the number of UUVs required to achieve different probabilities for different categories of non-cooperative underwater targets under different deployment radii can be calculated. This can be achieved by calculating the number of UUVs required for different probabilities for category A, category B, and category C non-cooperative underwater targets under a fixed deployment radius.

[0121] Step 6: Based on the criteria for whether different types of non-cooperative underwater targets can be captured, make a judgment for each non-cooperative underwater target at each simulation time.

[0122] The judgment criteria are as follows: when a non-cooperative underwater target is captured, stop moving; when a non-cooperative underwater target is not captured, continue moving towards the target; if the non-cooperative underwater target is not captured, stop moving when the distance between the non-cooperative underwater target and the target is less than 3.

[0123] Step 7: When all non-cooperative underwater targets in this experiment stop moving, the experiment ends. Then, determine whether the number of experiments is greater than the set number of experiments. If it is greater, the experiment ends. If it is less, repeat steps 4 to 6 until the experiment ends. Calculate and display the defense probability of the inner and outer warning lines.

[0124] Preferably, in step one, the radius of the outer warning line can be selected from 8, 8.5, 9, 9.5, and 10, with a default initial value of 10; the radius of the inner warning line can be selected from 1.0, 1.5, 2.0, 2.5, and 3.0, with a default initial value of 3; the detection radius of the UUV for non-cooperative underwater targets of categories A, B, and C is adjustable from 0.8 to 1.5, with default initial values ​​of 1.5, 0.8, and 0.8, respectively; the detection radius of non-cooperative underwater targets of categories A, B, and C for the UUV is 0.8 times the detection radius of the UUV for non-cooperative underwater targets of categories A, B, and C, respectively, with default initial values ​​of 1.2, 0.64, and 0.64, respectively; the speed of the UUV can be selected from 4, 6, and 8 knots, with a default initial value of 4 knots; the speed of non-cooperative underwater targets of categories A, B, and C can be selected from 1, 2, 3, and 4 knots, with default initial values ​​of 4, 3, and 2 knots, respectively.

[0125] There are three configuration options for non-cooperative underwater targets: the first configuration is 2 Class A non-cooperative underwater targets, 1 Class B non-cooperative underwater target, and 1 Class C non-cooperative underwater target; the second configuration is 1 Class A non-cooperative underwater target, 2 Class B non-cooperative underwater targets, and 1 Class C non-cooperative underwater target; the third configuration is 1 Class A non-cooperative underwater target, 1 Class B non-cooperative underwater target, and 2 Class C non-cooperative underwater targets. The number of Monte Carlo runs can be selected from an integer between 1 and 500, with a default initial value of 4.

[0126] The UUV has three patrol modes: Patrol Mode 1, Patrol Mode 2, and Patrol Mode 3, with Patrol Mode 1 being the default initial mode. The radius of the island can be selected from 0.5, 1.0, 1.5, 2, and 2.5, with a default initial value of 0.5. The basic detection probability can be selected from 0.5, 0.6, 0.7, 0.8, and 0.9, with a default initial value of 0.5. When a non-cooperative underwater target is within the UUV's detection range, the probability of dt increasing at each moment can be selected from 0.05, 0.1, 0.15, 0.2, and 0.25, with a default initial value of 0.05.

[0127] Among them, patrol mode 1 is for all UUVs to move in a circle; patrol mode 2 is for all UUVs to move back and forth; patrol mode 3 is for all UUVs to move in a circle with increased speed, reaching the maximum speed.

[0128] Preferably, in step three, the bistatic sonar simultaneously possesses the operational characteristics of both active and passive sonar, including: the transmitting station emitting acoustic pulses, illuminating the target, the acoustic waves being scattered by the target to generate target echoes, and the receiving station receiving the target echoes at different locations; the transmitting station operates in an active mode, while the receiving station operates in a passive state because it only receives target echoes; therefore, based on the operational characteristics of bistatic sonar, its sonar equations also exist in two forms, including...

[0129] For noise-limited conditions, the equations for bistatic sonar are as follows:

[0130] SL-TL1-TL2+TS-NL+DI=DT

[0131] For reverberation-limited cases, the sonar equation is:

[0132] SL-TL1-TL2+TS-RL+DI=DT

[0133] In the formula, TL1 and TL2 are the propagation losses from the sound source to the target and from the target to the receiver, respectively. Under bistatic conditions, the two propagation distances experienced by the sound wave and the absorption factors on the two propagation paths can be different, and TL1 and TL2 will not be exactly the same.

[0134] Under bifocal conditions, the propagation loss is,

[0135] TL = TL1 + TL2

[0136] In the formula, TL1 represents the propagation loss from the sound source to the target, and is equal to the distance r from the transmitter to the target. T Related, denoted as TL1(r) T ); TL2 represents the propagation loss from the target to the receiver, and is equal to the distance r from the target to the receiver. R Related, denoted as TL2(r) RGiven that SL, TS, NL, DI, and DT are all determined, the effective range of bistatic sonar satisfies the following conditions.

[0137] TL1(r T )+TL2(r R =SL + TS - NL + DI - DT = constant

[0138] At this point, the effective range of the sonar depends only on r. R The possible values ​​of ;

[0139] Clearly, in the above formula, r R The smaller r is T The larger the value, the greater the value; however, in reality, r R On the one hand, it's an unknown quantity; on the other hand, it can't be too small, otherwise the direct wave and the target echo will be difficult to separate in the time domain. Assuming that signal processing methods can separate the direct wave and the echo in the spatial domain, then a certain r can be set... R After determining the value, estimate the effective range of the bistatic sonar; the lower the operating frequency, the smaller the propagation loss, and the better the effect of the bistatic sonar; the higher the sonar quality factor, the more obvious the effect.

[0140] To compare the detection radii between monostatic and bistatic sonar, the detection areas of monostatic and bistatic sonar systems are theoretically derived below:

[0141] Assume the target intensity is 20 dB for monostatic sonar and 15 dB for bistatic sonar. Source level SL = 210 dB. Noise source shielding level:

[0142] NL-DI+DT=60dB

[0143] To make it more feasible, the sound wave propagation loss is considered based on spherical spread plus seawater absorption, that is:

[0144] TL = 20lgr + αr + NL - DI + DT

[0145] Where α is the acoustic absorption coefficient. Substituting the above data into the bistatic sonar equations, we get:

[0146] 20lgr T +αr T +60+20lgr R +αr R +60 = 210 - 60 + 15 = 165

[0147] 20lgr T ·r R +α(r T +r R ) = 45

[0148] The approximate formula for the absorption coefficient in seawater within the frequency range of 0.5kHz to 100kHz is:

[0149]

[0150] When the frequency is 10kHz:

[0151]

[0152] therefore:

[0153] 20lg(r T ·r R )+1.18(r T +r R ) = 45

[0154] When the distance between the sonar transmitter and the non-cooperative underwater target is 1 km, i.e. r T =1km, substituting into the above equation, we can find r. R It is approximately 16.2 km.

[0155] 20lgr R +1.18(1+r R ) = 45

[0156] r R ≈16.2

[0157] This is 10.8 times the single-base detection radius of 1.5km.

[0158] Preferably, the number of UUVs required to achieve different probabilities for different categories of non-cooperative underwater targets under different deployment radii can be calculated through Monte Carlo experiments. This can be achieved by calculating the number of UUVs required for different probabilities for category A, category B, and category C non-cooperative underwater targets under a fixed deployment radius.

[0159] Preferably, combined with Figures 4 to 6 As shown, when UUVs are deployed on a circle with a radius of 7km, the number of UUVs required to achieve a certain probability for a single-base deployment is far greater than the number required for a multi-base deployment. Therefore, the cost of a multi-base deployment is lower than that of a single-base deployment. Through Monte Carlo experiments, when the number, speed, and detection range of UUVs are the same, comparing the defense probability of a single-base and a multi-base deployment, the defense probability of a multi-base deployment is better than that of a single-base deployment.

[0160] Therefore, in actual situation simulation, six UUVs are evenly distributed on a circle with a radius of 7 to form a multi-base sonar system with one transmitting sonar and six receiving sonars. The patrol mode is to make uniform circular motion on the circle.

[0161] Preferably, combined with Figure 7 As shown, Figure 7 This is a diagram of the situation simulation GUI interface, through which simulation parameters for detecting non-cooperative underwater targets can be set.

[0162] The entire situation simulation process demonstrated the movement of non-cooperative underwater targets and the entire process of UUV cooperative detection. When a non-cooperative underwater target was captured, its color turned red. When each non-cooperative underwater target was either captured or had broken through the defense perimeter, the Monte Carlo experiment ended, and the next experiment was conducted until the set number of Monte Carlo runs was reached.

[0163] Specific implementation plan two: an underwater target detection situation simulation system in UUV collaborative operations, which has program modules corresponding to the above steps, and executes the steps in the above-mentioned underwater target detection situation simulation method in UUV collaborative operations when running.

[0164] The other combinations and connections in this implementation scheme are the same as in Specific Implementation Scheme 1.

[0165] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for simulating the underwater target detection situation in UUV collaborative operations, characterized in that, Comprising the following steps: Step 1: setting simulation parameters, wherein the simulation parameters include an outer cordon radius, an inner cordon radius, the detection radius of a UUV for a class A non-cooperative underwater target, the detection radius of a UUV for a class B non-cooperative underwater target, the detection radius of a UUV for a class C non-cooperative underwater target, the respective detection radii of a class A non-cooperative underwater target, a class B non-cooperative underwater target and a class C non-cooperative underwater target for the UUV, the motion speed of the UUV, the motion speeds of a class A non-cooperative underwater target, a class B non-cooperative underwater target and a class C non-cooperative underwater target, the quantity configuration of non-cooperative underwater targets, the number of Monte Carlo times, the patrol mode of the UUV, the radius of an island, a basic detection probability and an increased probability; Step 2: selecting a motion mode of a non-cooperative underwater target, wherein the motion modes of the non-cooperative underwater target are divided into a linear motion mode and a DWA path planning-based motion mode; Step 3: constructing a formation for UUVs according to defense probability indexes of inner and outer cordons; Under the bistatic condition, a triangular relationship is formed among a sound source, a target and a receiver, and the detection range of a sonar is an ellipse; When only noise limitation is considered, the bistatic sonar equation is: In the formula, , These represent the propagation losses from the sound source to the target and from the target to the receiver, respectively. SL is the sound source level, TS is the target intensity, NL is the ship's self-noise and ambient noise levels received by the receiving hydrophone array, DI is the directivity index of the receiving hydrophone array, DT is the detection threshold, and the noise masking level is NL-DI+DT. When the system parameters of the sonar system and the sea state are determined, the sound source level and the noise masking level are determined values; while TS, TL1 and TL2 change along with the change of the geometric relationship between the target and the bistatic sonar; (1) Regarding the value of TS: Under bistatic conditions, TS depends on two quantities: the incident angle and the split angle of the sound wave; by statistically averaging the TS values ​​of each incident angle and split angle under bistatic conditions according to certain rules, we obtain ,by Instead of using the random TS for range estimation, the final sonar coverage area is a regularly shaped ellipse; (2) Regarding propagation loss and effective range: the distance r between TL1 and the transmitter and target T Related, denoted as TL1(r) T Similarly, TL2 and the distance r from the target to the receiver are also related. R Related, denoted as TL2(r) R Given that SL, NL, TS, DI, and DT are all determined, the equations for bistatic sonar are: If the sound wave propagation loss is calculated according to spherical wave attenuation and absorption attenuation is ignored, then: Substituting into the bistatic sonar equation gives: Further derivation gives: (3) For the detection range and detection area, the distance between the sound source and the receiver is defined as D, and the equivalent radius of the bistatic system is... ; When D=0, the detection range of the bistatic system is a circle with radius R; with the increase of the parameter D, when 0<D<1.41R, the detection range of the bistatic sonar system gradually changes from a circle to an approximate ellipse; when D gradually exceeds 1.41R, the detection range of the bistatic sonar gradually begins to distort from the ellipse; when D is further increased to 2R, the detection range of the bistatic sonar system will be divided into two mutually disjoint regions; Therefore, 0<D<1.41R is defined as the optimal distance between the sound source level and the receiver for bistatic sonar, and the detection range of the bistatic sonar system can be regarded as an ellipse in this case; Step 4: in order to check whether the position configuration can meet the index, the Monte Carlo test is adopted to enable different types of non-cooperative underwater targets to move towards a target position from different directions each time; Step 5: calculating the states of the non-cooperative underwater target, the UUV and the transmitting sonar at each simulation moment, wherein the states refer to the abscissa, the ordinate, the heading angle, the speed and the angular velocity; Step 6: judging each non-cooperative underwater target at each simulation moment according to the judgment basis for whether different types of non-cooperative underwater targets can be intercepted; Step 7: when all non-cooperative underwater targets stop moving in the current test, the current test ends, then it is judged whether the number of tests is greater than the set number of tests, if yes, the test ends, if not, repeat steps 4 to 6 until the end, the defense probabilities of the inner cordon and the outer cordon are calculated and displayed.

2. The underwater target detection situation simulation method in UUV cooperative operations according to claim 1, characterized in that: In step 2, when the motion mode of the non-cooperative underwater target is the linear motion mode, the linear motion model is: in, X represents the motion state of the target. new X represents the current motion state of the target. old It represents the target's state of motion at the previous moment. The x-coordinate represents the target location. The vertical coordinate represents the target location. The heading angle representing the target. Represents the speed of the target's movement. Represents the angular velocity of the target; Represents a time interval; It represents the velocity and angular velocity at the current moment.

3. The underwater target detection situation simulation method in UUV cooperative operations according to claim 1, characterized in that: In step two, when the non-cooperative underwater target's motion mode is the DWA path planning motion mode, the current position and velocity state of the non-cooperative underwater target are considered in the velocity space. A sampling velocity space that satisfies the hardware constraints of the non-cooperative underwater target is determined. Then, the trajectory of the non-cooperative underwater target moving under these velocities for a certain period of time is calculated, and the trajectory is evaluated by an evaluation function. Finally, the velocity corresponding to the trajectory with the best evaluation is selected as the velocity of the non-cooperative underwater target. This process is repeated until the non-cooperative underwater target reaches the target point.

4. The underwater target detection situation simulation method in UUV cooperative operations according to claim 3, characterized in that, Includes the following steps: S1. Velocity sampling of non-cooperative underwater targets. Under velocity boundary constraints, the sampleable velocity space at this time for, In the formula , These are the minimum and maximum linear velocities of a non-cooperative underwater target, respectively. These are the minimum and maximum angular velocities of a non-cooperative underwater target, respectively. Under acceleration constraints, the sampleable velocity space at this time for, In the formula , These are the linear velocity and angular velocity of the non-cooperative underwater target at the current moment, respectively. , These are the maximum linear acceleration and maximum angular acceleration of the non-cooperative underwater target, respectively, and ∆t is the time difference between the current moment and the previous moment for the non-cooperative underwater target. Under the constraints of environmental obstacles, the velocity space that can be sampled at this time for, In the formula v represents the closest distance between the simulated trajectory of a non-cooperative underwater target and an obstacle at the current speed. min For the minimum linear velocity of a non-cooperative underwater target, ω min This represents the minimum angular velocity of the mobile robot. Combining the above three types of velocity constraints, the final non-cooperative underwater target velocity sampling space It is the intersection of three velocity spaces, that is, S2. Perform trajectory prediction for non-cooperative underwater targets, and determine the velocity sampling space in the trajectory prediction. Then, the DWA algorithm samples uniformly in the space at a certain sampling interval. After sampling a set of samples... Then, trajectory prediction, i.e., position update, is performed using the kinematic model of the non-cooperative underwater target; S3. Conduct trajectory evaluation for non-cooperative underwater targets. In the trajectory evaluation, multiple sets of sampled trajectories need to be evaluated and the best one is selected by comparing scores through standard evaluation trajectories. Then, the velocity corresponding to the best trajectory is selected as the driving velocity.

5. The underwater target detection situation simulation method in UUV cooperative operations according to claim 4, characterized in that: The evaluation function for assessing each trajectory is: in, It is the azimuth evaluation function, i.e. , This represents the error in the angle between the direction of the trajectory endpoint and the line connecting the target point at the current sampling speed. It is a distance evaluation function, representing the closest distance between the simulated trajectory and the obstacle at the current speed; It is a speed evaluation function that represents the current speed, which can be directly represented by the current linear velocity. The larger the current linear velocity, the faster the speed on the planned trajectory, and the higher the evaluation score. and All of these are coefficients of the evaluation function; This indicates normalization.

6. The underwater target detection situation simulation method in UUV cooperative operations according to claim 5, characterized in that: Monte Carlo experiments can be used to calculate the number of UUVs required to achieve different probabilities for different categories of non-cooperative underwater targets under different deployment radii. This can be achieved by calculating the number of UUVs required for different probabilities for category A, category B, and category C non-cooperative underwater targets under a fixed deployment radius.

7. The underwater target detection situation simulation method in UUV cooperative operations according to claim 6, characterized in that: In step six, the criterion for determining whether different types of non-cooperative underwater targets have been captured is whether to stop moving. When a non-cooperative underwater target is captured, the movement stops; when a non-cooperative underwater target is not captured, the movement continues toward the target. If a non-cooperative underwater target is not captured, the movement stops when the distance between the target and the target is less than 3.

8. A simulation system for underwater target detection situation in UUV collaborative operations, characterized in that: The system has a program module corresponding to the steps of any one of the claims 1-7 above, and executes the steps in the above-described UUV collaborative operation underwater target detection situation simulation method when running.

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