Method for threat assessment of unknown target by unmanned surface vehicle in island reef patrol defense

Abstract

The application discloses a threat evaluation method for an unmanned ship to a strange target in island reef patrol defense, and belongs to the field of autonomous threat evaluation of the unmanned ship. The application calculates the relative position of the strange target and the irregular geometric boundary of the island reef defense area, analyzes whether the current route of the target intersects with the irregular geometric boundary, judges whether the strange target invades the island reef defense area, and respectively calculates the threat degree of the target invading or passing through the island reef defense area. The application makes up the deficiency that the influence of the position relationship between the target and the irregular geometric boundary of the defense area on the threat evaluation is ignored in the existing threat evaluation method, and is beneficial to the autonomous interception decision of the unmanned ship after the threat evaluation.

Description

Technical Field

[0001] This invention relates to the field of autonomous threat assessment of unmanned surface vessels (USVs), and more particularly to a method for assessing the threat of unfamiliar targets by USVs during island and reef patrol and defense. Background Technology

[0002] Unmanned surface vessel (USV) swarms have significant application value in island and reef patrol and defense. Multiple USVs deployed around the coastline of islands and reefs can promptly detect unfamiliar targets. By conducting threat assessments of these targets, USVs can be assigned to intercept high-threat targets nearby, effectively countering reconnaissance, infiltration, and other activities by unfamiliar targets and protecting the security of the island and reef defense area. In island and reef patrol and defense, accurate and reasonable threat assessment of detected targets by USVs is crucial for the successful execution of target interception missions.

[0003] Regarding target threat analysis, patent CN 111950117 A provides a method for calculating target threat level. By continuously measuring the speed of each threatening target and the relative distance between the threatening target and the protected target, it calculates the time it takes for the threatening target to arrive at the protected target, and then ranks the threats from highest to lowest according to arrival time. Patent CN111780620 A comprehensively considers the UAV modification attributes and the safe distance between the UAV and the no-fly zone to classify the potential threat level of UAVs. CN 109740876 A, when analyzing aerial target threats, calculates the target's threat intent by the direction of movement of the threatening target relative to the protected target and the target's orientation; calculates the penetration probability by the target's speed and maximum maneuverability; and quantitatively calculates and evaluates the target's threat level by comprehensively considering the target's threat intent, penetration probability, and damage capability. Zheng Shujian et al. (Zheng Shujian, Zhao Wenjie, Zhong Yongjian, et al. Research on collaborative task allocation method for multi-target interception problem [J]. Aerospace Defense, 2021, 4(3):55-64.) treated the incoming target and the interceptor missile as point masses in the problem of target threat capability assessment, and considered the influence of the relative distance, relative speed and relative angle between the two points on the degree of threat, and quantitatively solved the threat capability of the incoming target to the interceptor missile.

[0004] Existing target threat assessment methods primarily calculate the threat level of an incoming target based on the relative distance and orientation between the attacking and defending targets. Similarly, in area defense, the defense area can be expanded into a regular circular region, and the relative distance and velocity between the threatening target and the geometric center of the defense area, along with the angle between the relative distance and velocity and the line connecting the target and the center of the defense area, can be calculated to complete the target threat assessment. However, this approach in area defense easily overlooks the impact of the actual distances between the sides of the irregular defense area and the target, and the angle between the irregular boundary of the defense area and the target's velocity direction, on the target threat assessment results, potentially leading to misjudgments. For example, a threatening target might intrude into the virtual circular defense area in its current course, but not into the actual irregular defended area. Using the aforementioned threat analysis methods can easily lead to inaccurate threat assessment information. In the case of multiple targets intruding simultaneously, it ignores the different threat levels of targets intruding from different directions to different parts of the defended area, hindering patrolling unmanned surface vessel (USV) swarms from prioritizing and intercepting targets based on their threat levels, and easily causing USVs to fail to intercept targets in irregular area defense.

[0005] In island and reef defense, the equidistant coastal patrol lines around islands and reefs are generally irregular polygons. The existing methods for calculating the threat level of incoming targets by using information such as the relative distance, orientation, and speed between the target point and the geometric center point of the defense area are obviously insufficient. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing methods for assessing the threat of unfamiliar targets, which are difficult to apply directly to the analysis of the threat of unfamiliar targets in the patrol and defense of unmanned surface vessel swarms in irregular island and reef areas.

[0007] To achieve the above objectives, the technical solution of the present invention provides a method for assessing the threat of unmanned surface vessels (USVs) to unfamiliar targets during island and reef patrol and defense, characterized by comprising the following steps:

[0008] Step 1: Represent the irregularly equidistant coastal patrol line of the island and reef area to be protected as an irregular geometric polygon formed by connecting multiple waypoints. The set of vertices of this irregular geometric polygon can be represented as S = {S1, S2, ..., S...} i S n}, the i-th vertex S i The position coordinates are V i , where n is the total number of vertices of the irregular geometric polygon, and the area within the irregular geometric polygon is the unmanned surface vessel protection zone;

[0009] Step 2: When an unmanned surface vessel (USV) on the coastal patrol line of the island / reef area to be protected detects an unfamiliar target j in the vicinity, the USV determines the speed v of the detected target j based on the speed v of the target j. j Location P j It will pass through the target's current position Pj and along the target velocity v j The direction of the line is defined as the target route. The determination is made as to whether the unmanned surface vessel's protected area within the irregular geometric polygon will be intruded upon by target j.

[0010] If target j intrudes into the unmanned surface vessel protection area within an irregular geometric polygon, the threat level of target j is calculated by calculating the shortest distance between the target point and the intersection of the target route and each point of the irregular geometric polygon.

[0011] If target j does not intrude into the unmanned surface vessel protection area within the irregular geometric polygon, the threat level of target j is calculated by calculating the distance from the target j when it travels from its current position along the current target route to the point closest to the vertex of the irregular geometric polygon.

[0012] Step 3: The unmanned surface vessel sorts all the unfamiliar targets it discovers from highest to lowest threat level, and obtains the threat level ranking results of all targets.

[0013] Preferably, in step 1, the irregular equidistant coastal patrol line is represented as an irregular geometric polygon by a piecewise interpolation method.

[0014] Preferably, in step 1, the vertices of the irregular geometric polygon are arranged in a counterclockwise or clockwise order.

[0015] Preferably, in step 2, the lines connecting the target j to the two vertices of each side of the irregular geometric polygon and the target velocity v are... j The angle between directions is used to determine whether the protected area of ​​the unmanned surface vessel within the irregular geometric polygon will be invaded by the target j.

[0016] Preferably, in step 2, the target j and vertex S are defined. i The connecting vector is L j，i ,i=1,2,...,n, and S n+1 =S1, calculate the target velocity v j With L j，i The included angle α j1 ;

[0017] Define target j and vertex S i+1 The connecting vector is L j，i+1 Calculate the target velocity v j With L j，i+1 The included angle α j2 ; Calculate L j，i With L j，i+1 The included angle α j3 ;

[0018] Based on the included angle α j1 Angle α j2 and included angle αj3 Determine whether the protected area of ​​the unmanned surface vessel within the irregular geometric polygon will be invaded by the target j.

[0019] Preferably, if there exists a vertex S i S i+1 An edge such that α j1 <α j3 And α j2 <α j3 If the target j intersects the irregular polygon at its current speed and heading, it indicates that the target j will intrude into the protected area;

[0020] If there is no edge such that α j1 <α j3 And α j2 <α j3 Then target j moves at the current target speed v j It will not intrude into the protected area of ​​the unmanned surface vessel within the irregular geometric shape, but will only pass through the protected area of ​​the unmanned surface vessel.

[0021] Preferably, if target j is likely to intrude into the protected area, the following steps are used to calculate the threat level T of target j. j :

[0022] a) Calculate the target j from the current position P j The route to the target and the two vertices is S. i S i+1 The distance between the intersection points of the edges (if i = n, then it is the distance between the two endpoints S) n D, the intersection of the edges of S1 j，i Then we have:

[0023]

[0024] b) Considering the possibility that multiple edges of an irregular geometric polygon may intersect with the target route of target j, find the minimum distance D from the current position of target j to each intersection point. in，j =min{D j，i If the threat level of target j is T, then the threat level of target j is T. j The calculation is as follows:

[0025]

[0026] In the formula, K1 is the threat constant of the incoming unfamiliar target;

[0027] If target j only passes through the unmanned surface vessel's protected area, the following steps are used to calculate the threat level T of target j. j :

[0028] 1) Calculate the S values ​​of each vertex on the side of the irregular geometric polygon. iThe perpendicular distance D between the target flight path of target j and target i = 1, 2, ..., n. j，i :

[0029] If α j1 >α j3 Then D j，i =||L j，i+1 ||·sin(α j2 );

[0030] If α j2 >α j3 Then D j，i =||L j，i ||·sin(α j1 );

[0031] 2) Find the point i among all vertices that has the shortest perpendicular distance to the target flight path, and calculate the distance from the current position P to the target j. j Travel along the target route to the point closest to that vertex. out，j :

[0032]

[0033] 3) Calculate the threat level T of target j. j :

[0034]

[0035] In the formula, K2 is the threat constant of targets passing through the protected area of ​​the unmanned surface vessel, and K1 > K2.

[0036] Preferably, the included angle α j1 The calculation formula is:

[0037] Preferably, the included angle α j2 The calculation formula is:

[0038] Preferably, the included angle α j3 The calculation formula is:

[0039] This invention proposes a threat assessment method for unmanned surface vessels (USVs) posing a threat to intruding targets during island and reef patrol and defense, overcoming the shortcomings of existing target threat assessment methods that fail to consider the impact of irregular geometric features of the defense area on target threats. Compared with the prior art, this invention has the following significant advantages:

[0040] By approximating the equidistant coastal patrol lines around islands and reefs as irregular geometric polygons, the distance, orientation, and fastest estimated arrival time of unfamiliar targets relative to each side of the irregular geometric polygons are calculated. The differences in the unfamiliar target's route and the threat level of the intrusion defense area are also considered. The fastest estimated arrival time is used to measure the threat level of unfamiliar targets in the defense of irregular island and reef areas. This effectively makes up for the shortcomings of existing target threat methods that ignore the influence of irregular area boundaries on the calculation of target threat in area defense. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of an unfamiliar target intruding into an island and reef area within an irregular polygon.

[0042] Figure 2 This is a schematic diagram of the defensive zone within an irregular polygon representing the path of an unfamiliar target.

[0043] Figure 3 This is a process for assessing the threat of unmanned surface vessels to unfamiliar targets during island and reef patrol and defense.

[0044] In the attached diagram: 1-Irregular islands and reefs, 2-Irregular geometric polygons representing coastal patrol lines, 3-Vertexes of the irregular geometric polygons, 4-Unfamiliar targets, 5-Trajectory lines of unfamiliar targets. Detailed Implementation

[0045] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0046] This embodiment discloses a method for assessing the threat of unmanned surface vessels (USVs) to unfamiliar targets during island and reef patrol and defense, comprising the following steps:

[0047] Step 1: The irregularly equidistant coastal patrol line of the island and reef area to be protected is represented as an irregular geometric polygon formed by connecting multiple waypoints using a piecewise interpolation method. The vertices of this irregular geometric polygon are ordered counterclockwise, and the vertex set can be represented as S = {S1, S2, ..., S...}. i S n}, the i-th vertex S i The position coordinates are V i , where n is the total number of vertices of the irregular geometric polygon, and the area within the irregular geometric polygon is the unmanned surface vessel protection zone.

[0048] Step 2: When an unmanned surface vessel (USV) on the coastal patrol line of the island / reef area to be protected detects an unfamiliar target j in the vicinity, the USV determines the speed v of the detected target j based on the speed v of the target j. j Location Pj Determine whether the protected area of ​​the unmanned surface vessel within the irregular geometric polygon will be intruded upon by target j:

[0049] If target j intrudes into the unmanned surface vessel protection zone within an irregular geometric polygon, then the target point and target route (the target route passes through the target's current position P) are calculated. j and along the target velocity v j The threat level of target j is calculated by the shortest distance between the intersection points of the line of direction and the irregular geometric polygon.

[0050] If target j does not intrude into the unmanned surface vessel protection zone within the irregular geometric polygon, the threat level of target j is calculated by measuring the distance from the target j when it travels from its current position along the current target route to the point closest to the vertex of the irregular geometric polygon.

[0051] Step 2 further includes the following steps:

[0052] Step 201: Obtain the velocity v of target j. j and position P j The current position P of the target j will be passed. j and along the target velocity v j The directional line is defined as the target route, and the relative positional relationship between each side of the irregular geometric polygon representing the coastal patrol line and the target route is analyzed.

[0053] When i≠n, the two endpoints of each side of the irregular geometric polygon are respectively represented by S. i S i+1 This indicates that when i = n, the two endpoints of each side of the irregular geometric polygon are represented by S. n S1 represents the relative positional relationship between the sides of the irregular geometric polygon representing the coastal patrol line and the target route. This is achieved by calculating the relationship between the target j and the lines connecting the two endpoints of each side of the irregular geometric polygon to the target velocity v. j The included angle of the direction further includes the following steps:

[0054] Step 2011: Define target j and vertex S i The connecting vector is L j，i Then L j，i =V i -P j Target speed v j With L j，i The included angle is α j1 Then we have:

[0055]

[0056] Step 2022: Define the target j and vertex S. i+1 The connecting vector is Lj，i+1 Then L j，i+1 =V i+1 -P j Target speed v j With L j，i+1 The included angle is α j2 Then we have:

[0057]

[0058] Step 2023, Define L j，i With L j，i+1 The included angle is α j3 Then we have:

[0059]

[0060] Step 202: If there exists a vertex S i S i+1 The edge (if i = n, then the two endpoints are S) n (edges S1 and S1) such that α j1 <α j3 And α j2 <α j3 If target j, at its current speed and heading, intersects the irregular polygon, it indicates that target j will intrude into the protected area. The following steps are then used to calculate the threat level T of target j. j :

[0061] a) Calculate the target j from the current position P j The route to the target and the two vertices is S. i S i+1 The distance between the intersection points of the edges (if i = n, then it is the distance between the two endpoints S) n D, the intersection of the edges of S1 j，i Then we have:

[0062]

[0063] b) Considering the possibility that multiple edges of an irregular geometric polygon may intersect with the target route of target j, find the minimum distance D from the current position of target j to each intersection point. in，j =min{D j，i If the threat level of target j is T, then the threat level of target j is T. j The calculation is as follows:

[0064]

[0065] In the formula, K1 is the threat constant of the incoming unfamiliar target.

[0066] If there is no edge such that α j1 <α j3 And αj2 <α j3 Then target j moves at the current target speed v j If the unmanned surface vessel (USV) will not intrude into the protected area of ​​an irregularly shaped geometric shape, but only passes through the protected area, then the following steps are used to calculate the threat level T of target j. j :

[0067] 1) Calculate the S values ​​of each vertex on the side of the irregular geometric polygon. i The perpendicular distance D between the target flight path of target j and target i = 1, 2, ..., n. j，i :

[0068] If α j1 >α j3 Then D j，i =||L j，i+1 ||·sin(α j2 );

[0069] If α j2 >α j3 Then D j，i =||L j，i ||·sin(α j1 ).

[0070] 2) Find the point i among all vertices that has the shortest perpendicular distance to the target flight path, and calculate the distance from the current position P to the target j. j Travel along the target route to the point closest to that vertex. out，j :

[0071]

[0072] 3) Calculate the threat level T of target j. j :

[0073]

[0074] In the formula, K2 is the threat constant of the target passing through the unmanned surface vessel protection area, and K1 > K2, which indicates that the threat level of the target intruding into the unmanned surface vessel protection area is higher than that of the target passing through the unmanned surface vessel protection area.

[0075] Step 3: The unmanned surface vessel sorts all the unfamiliar targets it discovers from highest to lowest threat level, and obtains the threat level ranking results of all targets.

[0076] In this specification, the present invention has been described with reference to specific embodiments of the technical solutions, but various modifications and variations can still be made without departing from the principles and scope of the present invention. Therefore, the above are merely specific embodiments of the present invention and the technical principles applied. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the protection scope of the present invention.

Claims

1. A method for assessing the threat posed by unmanned surface vessels (USVs) to unfamiliar targets during island and reef patrol and defense, characterized in that... Includes the following steps: Step 1: Represent the irregularly equidistant coastal patrol line of the island / reef area to be protected as an irregular geometric polygon formed by connecting multiple waypoints. The set of vertices of this irregular geometric polygon can be represented as... , No. vertices The position coordinates are , The total number of vertices of the irregular geometric polygon; the area within the irregular geometric polygon is the unmanned surface vessel protection zone. Step 2: When unmanned surface vessels (USVs) along the coastal patrol line of the protected island / reef area detect unfamiliar targets in the vicinity... At that time, the unmanned surface vessel (USV) will determine the target based on its current detection. speed ,Location It will pass through the target's current location. and along the target speed The direction of the line is defined as the target route. The determination is made as to whether the unmanned surface vessel (USV) protection zone within the irregular geometric polygon will be affected by the target. Intrusion: Based on the goal Connect the lines to the two vertices of each side of the irregular geometric polygon and the target velocity. The angle between directions is used to determine whether the protected area of ​​the unmanned surface vessel within the irregular geometric polygon will be targeted by the target. Intrusion: Define goals With vertex The connecting vector is , ,and Calculate the target velocity and The included angle ; Define goals With vertex The connecting vector is Calculate the target velocity and The included angle ; calculate and The included angle ; Based on the included angle Angle and included angle Determine whether the protected area of ​​an unmanned surface vessel within an irregular geometric polygon will be targeted. Intrusion: If there exists a vertex as , The edge makes and Then the target At the current speed and heading, it will intersect with the irregular polygon, indicating the target. It will intrude into the protected area; If the target If an unmanned surface vessel (USV) intrudes into the protected area of ​​an irregular geometric polygon, the target's location is calculated by determining the shortest distance between the target point and the intersections of the target route and the irregular geometric polygon. The level of threat; If there is no edge such that and Then the target At the current target speed It will not intrude into the protected area of ​​the unmanned surface vessel within irregular geometric shapes, but will only pass through the protected area of ​​the unmanned surface vessel; If the target If the unmanned surface vessel does not intrude into the protected area within the irregular geometric polygon, the target distance is calculated by measuring the distance from its current position along the current target trajectory to the point closest to the vertex of the irregular geometric polygon. The level of threat; Step 3: The unmanned surface vessel sorts all the unfamiliar targets it discovers from highest to lowest threat level, and obtains the threat level ranking results of all targets.

2. The threat assessment method for unmanned surface vessels (USVs) against unfamiliar targets during island and reef patrol and defense as described in claim 1, characterized in that... In step 1, the irregular equidistant coastal patrol line is represented as an irregular geometric polygon using a piecewise interpolation method.

3. The threat assessment method for unmanned surface vessels (USVs) against unfamiliar targets during island and reef patrol and defense as described in claim 1, characterized in that... In step 1, the vertices of the irregular geometric polygon are arranged in either counterclockwise or clockwise order.

4. The threat assessment method for unmanned surface vessels (USVs) against unfamiliar targets during island and reef patrol and defense as described in claim 1, characterized in that... If the target If it would intrude into the protected area, the following steps are used to calculate the target. level of threat : 1) Calculate the target From current location The route to the target and the two vertices is , Distance between the intersection points of the edges (if) Then it is the same as the two vertices. , (intersection of the edges) Then we have: 2) Consider the irregular geometric polygon with multiple edges intersecting with the target. If the target routes intersect, then search for the target. Minimum distance from the current position to each intersection point Then the target level of threat The calculation is as follows: In the formula, The threat constant for incoming, unfamiliar targets; If the target The target is calculated by passing through the protected area of ​​the unmanned surface vessel only. level of threat : 1) Calculate the vertices of each side of the irregular geometric polygon. , With the goal Vertical distance of the target route : like ,but ; like ,but ; 2) Find the vertex with the shortest perpendicular distance to the target flight path. Calculate the target From current location Distance to the point closest to the vertex along the target route : 3) Calculate the target level of threat : In the formula, Let be the threat constant of targets passing through the protected area of ​​the unmanned surface vessel, and .

5. The threat assessment method for unmanned surface vessels (USVs) against unfamiliar targets during island and reef patrol and defense as described in claim 1, characterized in that... The included angle The calculation formula is: .

6. The threat assessment method for unmanned surface vessels (USVs) against unfamiliar targets during island and reef patrol and defense as described in claim 1, characterized in that... The included angle The calculation formula is: .

7. The threat assessment method for unmanned surface vessels (USVs) against unfamiliar targets during island and reef patrol and defense as described in claim 1, characterized in that... The included angle The calculation formula is: .

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