Distributed underwater acoustic positioning method and network based on credible propagation of communication node information elements

Abstract

The application belongs to the technical field of underwater acoustic positioning, and discloses a distributed underwater acoustic positioning method and network based on credible propagation of communication node information elements. The application constructs a distributed underwater acoustic positioning network by deploying a plurality of communication nodes in a detection sea area, wherein the communication nodes include anchor nodes and common nodes; the information elements of the communication nodes include the position coordinates of the nodes, the position confidence of the nodes, the distance between the nodes and the nodes receiving data, and the information element update time; the anchor nodes obtain the position coordinates through self-positioning and fill the position coordinates into the information elements of the anchor nodes; the common nodes calculate the position coordinates and the position confidence by using the information elements of a plurality of adjacent nodes received and fill the position coordinates and the position confidence into the information elements of the common nodes; the communication nodes update the information elements of the nodes based on the information element update time and propagate the underwater acoustic signals to the underwater. The application can improve the accuracy and reliability of underwater acoustic positioning and reduce the deployment cost.

Description

Technical Field

[0001] This invention belongs to the field of underwater acoustic positioning technology, and more specifically, relates to a distributed underwater acoustic positioning method and network based on the reliable propagation of information elements of communication nodes. Background Technology

[0002] Underwater positioning is crucial for marine exploration, maritime operations, and underwater military activities. However, the underwater environment is largely blocked from light and electromagnetic waves, making long-distance underwater positioning difficult with GNSS and optical methods. Therefore, underwater acoustic positioning is currently the mainstream underwater positioning technology. Conventional underwater acoustic positioning technologies mainly include long baseline positioning, short baseline positioning, and ultra-short baseline positioning. However, these methods all require the fixed deployment of underwater acoustic communication nodes on the seabed, ships, or unmanned devices, resulting in high deployment costs, fixed and small monitoring areas, inability to conduct long-term monitoring, and a lack of flexibility.

[0003] Currently, distributed underwater acoustic positioning networks have become a research hotspot, but existing networks still suffer from various problems such as high deployment costs, the network range being controlled by anchor nodes equipped with satellite positioning devices, and the accuracy fluctuating greatly with the distribution and density of anchor nodes, resulting in significant limitations on the monitoring range. Summary of the Invention

[0004] This invention provides a distributed underwater acoustic positioning method and network based on the reliable propagation of information elements from communication nodes, thereby solving the problems of low accuracy, poor reliability, and high deployment cost in existing underwater acoustic positioning technologies.

[0005] This invention provides a distributed underwater acoustic localization method based on the reliable propagation of information elements of communication nodes, comprising:

[0006] A distributed underwater acoustic positioning network is constructed by deploying several communication nodes in the exploration area, the communication nodes including anchor nodes and ordinary nodes;

[0007] The information element E = {L, B, D, T} of the communication node is constructed; where L is the location coordinate of the node, B is the location confidence of the node, D is the distance between the node and the node receiving data, and T is the information element update time.

[0008] The anchor node obtains its position coordinates through self-localization and fills them into its own information elements; the ordinary node calculates its position coordinates and position confidence level using the information elements of multiple neighboring nodes it receives, and fills them into its own information elements.

[0009] The communication node updates its own information elements periodically based on the information element update time, and then transmits the updated information elements underwater as underwater acoustic signals.

[0010] Preferably, the ordinary node calculates its position coordinates using a spherical intersection model and a maximum likelihood algorithm based on the position coordinates of multiple neighboring nodes and the distances between the multiple neighboring nodes and the ordinary node.

[0011] The ordinary node calculates the distance between the neighboring node and the ordinary node based on the update time of the information elements in the information elements of the neighboring node and the actual time when the underwater acoustic signal corresponding to the neighboring node arrives at the ordinary node.

[0012] Preferably, the ordinary node calculates its position confidence score based on the position confidence scores of multiple neighboring nodes, and the formula for calculating the position confidence score is as follows: Where K is the propagation coefficient, B i Let Z be the position confidence of the i-th neighbor node, N be the number of neighbor nodes, and Z be the bias value.

[0013] Preferably, when updating the information elements of a common node, if the newly calculated position confidence of the common node exceeds its original value, then the newly calculated position coordinates and position confidence of the common node are used to overwrite its original value; otherwise, the position coordinates and position confidence of the common node calculated in this instance are discarded.

[0014] Preferably, each of the communication nodes also maintains a local set of information elements M = {E0, E1, E2, ..., E...} K}; where E0 is the information element of the node itself, E i The information element of neighbor node i received by this node, where i ranges from 1 to K, and K is the maximum number of neighbor nodes stored locally;

[0015] The communication node uses the local set of information elements for cross-validation and location updates; the communication node propagates the local set of information elements of the node or the information elements of the node itself in the local set of information elements to various directions underwater.

[0016] Preferably, for any of the communication nodes, D in the node's own information elements represents the distance between the node and itself, and the value of D in E0 is 0;

[0017] For any of the aforementioned communication nodes, the information element E received by that node from its neighbor node i i In this context, D represents the distance between the node and its neighboring node i; E iThe initial value of D in the table is 0. Based on the update time of the information elements in the information elements of neighboring node i and the actual time when the underwater acoustic signal of neighboring node i arrives at the node, the node calculates the distance between neighboring node i and the node, and updates and replaces the value of D.

[0018] For any of the communication nodes, the location confidence B of the node ranges from [0,1]; if the communication node is an anchor node, then the location confidence of the node is 1.

[0019] Preferably, when the communication node maintains its local set of information elements, it fills, overwrites, or discards information elements of a new neighboring node based on preset rules after receiving such information elements.

[0020] The preset rules include: if the local set of information elements is not full, then the information elements of the new neighboring node are added to the local set of information elements; if the local set of information elements is full, then it is determined whether the position confidence of the new neighboring node is higher than that of the original neighboring node, and whether the distance between the new neighboring node and the communication node is less than that between the original neighboring node and the communication node; based on the determination results, if the position confidence of the new neighboring node is higher and the distance is closer, then the information elements of the original neighboring node with lower position confidence or greater distance are replaced with the information elements of the new neighboring node; otherwise, the information elements of the new neighboring node are discarded.

[0021] When the information elements of neighboring nodes in the local information element set of the communication node are updated, the local information element set is updated and the updated local information element set is propagated in all directions underwater.

[0022] Preferably, the constructed distributed underwater acoustic positioning network also includes non-cooperative underwater targets and cooperative underwater targets;

[0023] When detecting and tracking underwater targets, for both non-cooperative and cooperative underwater targets, a communication node calculates the position information of the underwater target based on its own information elements, the detection information obtained by the node, and the detection information obtained by multiple neighboring nodes; the detection information includes the target's reflection characteristics and the distance between the underwater target and the node.

[0024] When the cooperative underwater target performs self-localization, it calculates the location information of the cooperative underwater target by using information elements sent by multiple nearby communication nodes.

[0025] On the other hand, the present invention provides a distributed underwater acoustic positioning network based on the reliable propagation of information elements of communication nodes, comprising: a plurality of communication nodes deployed in the detection sea area, wherein the communication nodes include anchor nodes and ordinary nodes;

[0026] The distributed underwater acoustic positioning network based on the reliable propagation of information elements of communication nodes is used to implement the steps in the above-mentioned distributed underwater acoustic positioning method based on the reliable propagation of information elements of communication nodes.

[0027] Preferably, the distributed underwater acoustic positioning network based on the reliable propagation of communication node information elements further includes: non-cooperative underwater targets and cooperative underwater targets;

[0028] The cooperative underwater target calculates its location information using information elements sent by multiple nearby communication nodes.

[0029] A communication node calculates the location information of an underwater target based on its own information elements, the detection information obtained by the node, and the detection information obtained by multiple neighboring nodes, thereby enabling the tracking and identification of the non-cooperative underwater target or the cooperative underwater target; the detection information includes the target's reflectivity and the distance between the underwater target and the node.

[0030] One or more technical solutions provided in this invention have at least the following technical effects or advantages:

[0031] This invention designs a distributed underwater acoustic positioning method based on the reliable propagation of information elements from communication nodes. The communication nodes include several anchor nodes and ordinary nodes deployed in the exploration area. The information elements of the communication nodes are E = {L, B, D, T}, where L is the position coordinates of the node, B is the position confidence of the node, D is the distance between the node and the node receiving the data, and T is the information element update time. The anchor nodes obtain their position coordinates through self-localization and fill them into their own information elements. The ordinary nodes calculate their position coordinates and position confidence using the information elements received from multiple neighboring nodes and fill them into their own information elements. The communication nodes update their own information elements periodically based on the information element update time and propagate the updated information elements underwater as underwater acoustic signals. The distributed underwater acoustic positioning method and network proposed in this invention allow anchor nodes to propagate reliable location information obtained from satellite navigation and communication underwater through an effective information propagation mechanism, providing ordinary nodes with a basis for their own positioning. Ordinary nodes obtain location and distance information from multiple neighboring nodes, including anchor nodes, calculate their own positions, and then provide positioning information to other ordinary nodes. The location information obtained or calculated by each node is shared in the network, evaluated and synthesized using a confidence index, which is updated and changed during the propagation process. Ultimately, reliable network positioning information is distributed throughout the network and cross-validated and corrected, thus giving underwater acoustic positioning high accuracy and high reliability, and improving the robustness of the entire network. This invention is a distributed underwater acoustic positioning network, which uses multiple array elements to better determine their own or target positions through information sharing. The positions of network array elements do not need to be fixed; they can join or leave at any time, which reduces deployment costs and improves network flexibility, facilitating the expansion of the monitoring range. In addition, this invention can also monitor non-cooperative targets and share monitoring information through multiple nodes, enabling a single node to track the target. It also allows partners to access their own information through the internet. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the initial node information propagation in a distributed underwater acoustic localization method based on the reliable propagation of communication node information elements provided in an embodiment of the present invention.

[0033] Figure 2 This is a flowchart illustrating the workflow of a distributed underwater acoustic positioning network based on the reliable propagation of information elements from communication nodes, as provided in an embodiment of the present invention. Detailed Implementation

[0034] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0035] Example 1:

[0036] Example 1 provides a distributed underwater acoustic localization method based on the reliable propagation of information elements of communication nodes, including:

[0037] (1) Construct a distributed underwater acoustic positioning network.

[0038] A distributed underwater acoustic positioning network is constructed by deploying several communication nodes in the exploration area. The communication nodes include anchor nodes and ordinary nodes.

[0039] This invention constructs a distributed underwater acoustic positioning network, primarily comprising: anchor nodes (i.e., underwater acoustic communication nodes equipped with satellite positioning and navigation devices) and ordinary nodes (underwater acoustic communication nodes not equipped with satellite positioning and navigation devices). Anchor nodes, typically in the form of buoys or lift-up buoys, receive satellite signals to determine their own position and transmit their position and other information underwater, sending a reference position signal to the underwater acoustic positioning network. Ordinary nodes can receive information from multiple anchor nodes and, combined with the distance to the anchor nodes calculated through time-of-flight, calculate their own position. Ordinary nodes and anchor nodes are collectively referred to as communication nodes, all possessing the function of providing positioning information to the underwater acoustic network, thereby enabling the construction of a decentralized, distributed, intelligent underwater acoustic positioning network.

[0040] (2) Constructing the information elements of communication nodes.

[0041] The information element E of the communication node is E = {L, B, D, T}. Where L is the node's location coordinates, recording the node's position; B is the node's location confidence level, representing a measure of the accuracy of the node's location coordinates, with a value range of [0, 1], where a larger value indicates more reliable location information; D is the distance between the node and the node receiving the data; and T is the information element update time.

[0042] Information elements of communication nodes are transmitted between adjacent nodes, enabling anchor nodes or ordinary nodes that have acquired their own location to share their location information throughout the underwater acoustic network.

[0043] (3) Reliable propagation and underwater acoustic positioning are achieved based on the information elements of communication nodes.

[0044] The anchor node obtains its position coordinates L through self-localization and fills them into its own information elements; the position confidence B of the anchor node is 1.

[0045] The ordinary node uses the information elements of multiple neighboring nodes received to calculate the position coordinates L and the position confidence B of the ordinary node, and fills them into the information elements of the ordinary node itself.

[0046] The communication node updates its own information elements periodically based on the information element update time T, and then transmits the updated information elements underwater as underwater acoustic signals.

[0047] Specifically, the ordinary node calculates its position coordinates using a spherical intersection model and a maximum likelihood algorithm, based on the position coordinates of multiple neighboring nodes and the distances between each neighboring node and the ordinary node. The ordinary node calculates the distance between itself and its neighboring nodes based on the update time of the information elements in the neighboring nodes' information elements and the actual arrival time of the underwater acoustic signal corresponding to the neighboring node.

[0048] The position confidence of a regular node is calculated based on the position confidence of multiple neighboring nodes. The formula for calculating the position confidence is as follows: Where K is the propagation coefficient, B i Let Z be the position confidence of the i-th neighbor node, N be the number of neighbor nodes, and Z be the bias value.

[0049] When updating the information elements of a common node, if the newly calculated position confidence of the common node exceeds its original value, then the newly calculated position coordinates and position confidence of the common node are used to overwrite its original value; otherwise, the position coordinates and position confidence of the common node calculated in this instance are discarded.

[0050] The preferred solution also includes:

[0051] (4) Construct a local set of information elements for communication nodes, and perform cross-validation and location updates based on the local set of information elements.

[0052] Each of the communication nodes also maintains a local set of information elements M = {E0, E1, E2, ..., E...} K}. Where E0 represents the information element of the node itself, E i The information element of neighbor node i received by this node, where i ranges from 1 to K, and K is the maximum number of neighbor nodes stored locally.

[0053] Based on the aforementioned local set of information elements, communication nodes can more efficiently perform cross-validation or update their own position coordinates using information from neighboring nodes. The communication node can then propagate its local set of information elements, or information elements from that local set, in various underwater directions.

[0054] Specifically, for any of the aforementioned communication nodes, D in the node's own information element represents the distance between the node and itself, and D in E0 takes a value of 0. For any of the aforementioned communication nodes, the information element E received by the node from its neighboring node i... iIn this context, D represents the distance between the node and its neighboring node i; E i The initial value of D in the equation is 0. Based on the update time of the information elements in the information elements of neighboring node i, and the actual arrival time of the underwater acoustic signal from neighboring node i, the node calculates the distance between neighboring node i and the current node, and updates the value of D accordingly. For any of the communication nodes, the location confidence B ranges from [0,1]; if the communication node is an anchor node, its location confidence is 1.

[0055] When a communication node maintains its local set of information elements, upon receiving information elements from a new neighboring node, it fills, overwrites, or discards them based on preset rules. These preset rules include: if the local set of information elements is not full, the information elements from the new neighboring node are added to the local set; if the local set is full, it is determined whether the location confidence of the new neighboring node is higher than that of the original neighboring node, and whether the distance between the new neighboring node and the communication node is less than the distance between the original neighboring node and the communication node; based on the determination results, if the new neighboring node has a higher location confidence and is closer, the information elements of the new neighboring node replace the information elements of an original neighboring node with a lower location confidence or a greater distance; otherwise, the information elements of the new neighboring node are discarded. When the information elements of neighboring nodes in the local set of information elements of the communication node are updated, the local set of information elements is updated, and the updated local set of information elements is propagated in all underwater directions. Furthermore, the node's own information elements can also be updated based on the updated local set of information elements.

[0056] (5) Add non-cooperative underwater targets and cooperative underwater targets to the distributed underwater acoustic positioning network to realize underwater target tracking and cooperative underwater target self-localization.

[0057] When detecting and tracking underwater targets, for non-cooperative underwater targets (i.e., unfamiliar or hostile underwater targets) or cooperative underwater targets (i.e., friendly underwater targets), a communication node calculates the position information of the underwater target based on its own information elements, the detection information obtained by the node, and the detection information obtained by multiple neighboring nodes of the node; the detection information includes the target's reflection characteristics and the distance between the underwater target and the node.

[0058] Since the non-cooperative underwater target cannot receive or parse information transmitted by the communication node, nor can it send information to the communication node, it only passively reflects acoustic signals. This invention utilizes the reflection of signals transmitted by the communication node by the non-cooperative underwater target; multiple communication nodes receive the reflected echo signals and calculate their location by combining the results.

[0059] When the cooperative underwater target performs self-localization, it calculates the location information of the cooperative underwater target by using information elements sent by multiple nearby communication nodes.

[0060] Because the cooperative underwater target can receive and parse information transmitted by the communication node, and can also send request and reply information to the communication node, it can not only be detected and tracked by the communication node like the non-cooperative underwater target, but also calculate its own position by combining the information elements sent by the communication node and the distance between them, thereby achieving underwater positioning of the target.

[0061] Example 2:

[0062] Corresponding to the distributed underwater acoustic positioning method provided in Embodiment 1, Embodiment 2 provides a distributed underwater acoustic positioning network based on the reliable propagation of communication node information elements, including: a number of communication nodes deployed in the detection sea area, the communication nodes including anchor nodes and ordinary nodes; the distributed underwater acoustic positioning network based on the reliable propagation of communication node information elements is used to implement the steps in the distributed underwater acoustic positioning method based on the reliable propagation of communication node information elements as described in Embodiment 1.

[0063] Furthermore, the distributed underwater acoustic positioning network based on the reliable propagation of information elements from communication nodes may also include: non-cooperative underwater targets and cooperative underwater targets. The cooperative underwater target calculates its location information using information elements transmitted by multiple neighboring communication nodes. A communication node, based on its own information elements, the detection information obtained by the node, and the detection information obtained by multiple neighboring nodes, comprehensively calculates the location information of the underwater target, thereby achieving tracking and identification of the non-cooperative or cooperative underwater target; the detection information includes the target's reflectivity and the distance between the underwater target and the node.

[0064] The present invention will now be further described.

[0065] Figure 1 This is a schematic diagram of the initial node information propagation. Taking a deployment of 3 anchor nodes as an example, anchor nodes 1 to 3 acquire their own location information Li via satellite or maritime communication. They then package the location coordinates L, confidence level B (reliable source, B set to 1), distance D (initially 0, calculated by the receiver based on propagation time), update time T, and other information into E. iThe information is then propagated into the underwater area. After receiving information from the three anchor nodes, node 4 uses the spherical intersection model and the maximum likelihood algorithm to determine its own position, and simultaneously calculates the confidence level of its own position using the confidence levels of the source nodes. It then packages the information into E4 and propagates it underwater. After receiving information elements from the three anchor nodes and node 4, node 5, as described above, jointly calculates its own position and confidence level, and packages its own information into E5 and propagates it into the monitoring area. Node 6 uses the information elements received from these five nodes to calculate its own position and confidence level, and propagates its own information E6 into the monitoring area. In this process, the anchor node coordinates and their relative positions are shared throughout the network and continuously updated through optimization algorithms. Cross-validation and correction are performed using the anchor node positions and the coupling relationships between nodes, which improves the accuracy of network positioning.

[0066] Subsequent node information propagation can be configured so that each node receives information elements from 5 neighboring nodes, calculates its own position and confidence level, and then propagates the calculated information to the monitoring area.

[0067] Figure 2 Here is a flowchart of the workflow of a distributed underwater acoustic positioning network based on the reliable propagation of information elements from communication nodes, as follows: Figure 2 As shown, anchor nodes in the network first acquire their own location information through satellite communication or surface communication. These anchor nodes then transmit their location coordinates and confidence levels to the underwater monitoring area. Ordinary nodes in the network receive information elements from communication nodes with known locations and calculate the distances between them based on signal propagation time. Using the information elements of these neighboring nodes, and employing spherical intersection and maximum likelihood methods, they calculate their own position and confidence levels, and assume the function of anchor nodes, transmitting their calculated information elements underwater. By continuously receiving information from neighboring nodes and updating and propagating their own information, the network eventually reaches a dynamic equilibrium. This allows targets to achieve self-localization, detection, and tracking by utilizing the information elements of the network nodes.

[0068] Utilizing the aforementioned distributed underwater acoustic localization network, this embodiment provides a distributed underwater acoustic localization method based on the reliable propagation of communication node information elements, including:

[0069] Multiple anchor nodes are deployed in the survey area. These anchor nodes typically float on the water as buoys or as buoy-type underwater moorings, periodically surfacing and acquiring their position by receiving satellite signals. Once a single anchor node has established its position as a buoy, it descends to a certain depth to operate, using its onboard pressure sensor to determine its depth and thus its coordinates. The anchor nodes drift with wind, waves, and currents, thus requiring them to periodically acquire and update their position throughout the operational period.

[0070] The anchor node periodically updates its local information element set M. After updating its own position, the anchor node fills the information into its own created and stored information element E0. Here, coordinate L is filled with the node's current position coordinates; confidence B is set to 1, because position coordinates obtained directly through satellite signals are considered reliable; distance D is set to 0 as previously described; and update time T is filled with the information update time. For neighboring node information elements E0 in the local information element set M... i Let i = 1 to K, where K is the maximum number of neighboring nodes stored locally. This value is determined based on a trade-off between node storage and computing power; for example, K = 5. Since this information has not yet been acquired at the specified time, all other elements, including L, B, and D, are set to the default value of 0, except for the update time T in the information element, which is filled with the information update time. After updating the local set M of information elements, the anchor node transmits its own information element E0 underwater by emitting an acoustic signal through an acoustic sensor.

[0071] The ordinary nodes update their local information element set M. Since anchor nodes require satellite receivers, which are relatively expensive, bulky, and energy-intensive, ordinary nodes are more commonly used in constructing distributed underwater acoustic positioning networks, in addition to a relatively small number of anchor nodes. Ordinary nodes typically operate underwater and do not have the capability to receive satellite signals. They communicate with other nodes via underwater acoustic signals to transmit positioning information. When an ordinary node receives information elements transmitted by a neighboring communication node, it copies them to its own local information element set M, thereby obtaining its neighbor node information element E. i The basic principle of copying is: fill in unused neighboring node information; cover neighboring node information with low confidence or that is far away (resulting in significant loss of information strength and reliability). The content to be filled or covered is E. i In this context, L is set as the node coordinates in the received neighbor node information elements; and based on the update time T of the received information elements, i.e., the transmission time, and the actual arrival time of the received signal (which can be detected by the matching field processing of the transmitted and received signals), the distance between the neighbor node and the ordinary node can be calculated and filled into its neighbor node information E. i The distance D in the middle.

[0072] After obtaining information elements from multiple neighboring nodes, the ordinary node can calculate its own position by comprehensively applying the positions of these nodes and their distances from itself, using spherical polygon intersection and maximum likelihood estimation.

[0073] Specifically, each node calculates the distance to its neighbors based on the time delay of the information received from them, thus assuming that the node is on a sphere with the neighbor as its center and the distance as its radius. Theoretically, the unique intersection of the four spheres determined by the four neighboring nodes is the node's own position. When the distance information calculated by the neighboring nodes has errors or when more than four neighboring nodes are obtained, the optimal estimated position can be obtained using the least squares method and the maximum likelihood criterion.

[0074] Let the coordinates of the adjacent nodes in the two-dimensional plane be l. i =(x i y i The coordinates of the node to be located are l = (x, y), and the distance between the neighboring nodes and the node to be located is d. i Let i = 1 to N. Therefore, there are N expressions: By simplifying and rewriting it in matrix form, the approximate solution L′=(X) can be calculated using the least squares method. T X) -1 X T Y, where

[0075] The confidence level of the current location is estimated by combining the confidence levels of its neighboring nodes. The calculation method is as follows:

[0076]

[0077] Among them, B i Let Z be the confidence score between the i-th node and its neighboring nodes, and Z be the bias value. This is set based on environment and experience, indicating that the sum of the confidence scores of neighboring nodes must be greater than this value; otherwise, the node's own position cannot be calculated. For example, setting it to 2 means that at least 3 neighboring nodes are needed to obtain valid position information. K is the propagation coefficient, used to adjust the change in confidence score during propagation. If the calculated confidence score estimate exceeds the original value, the calculated position and confidence score overwrite the original value; if the estimate is less than or equal to the original value, the calculated position coordinates are discarded.

[0078] Once the ordinary node calculates its own position, it also acquires the function of an anchor node. Therefore, as mentioned above, anchor nodes and ordinary nodes are collectively referred to as communication nodes. Each communication node broadcasts its information elements in all directions underwater, sharing information with the entire network.

[0079] As explained above, each communication node can maintain a local set of information elements M. This includes its own information element E0 and the information elements E0 of its K neighboring nodes. iWhen the elements in the local set of information elements of a communication node are updated, the communication node can recalculate and update its own location information using the method described above. Each node is both a sender and a receiver of information sharing, and its own location information will be cross-validated through multiple rounds of use and derivation, gradually approaching its true value.

[0080] The underwater positioning network can also locate and track cooperative or non-cooperative targets. When the target positioning and tracking function is activated, the acoustic signal emitted by the communication node reaches the non-cooperative underwater target, and its reflected signal returns to the source communication node and is received by it, enabling the communication node to identify the target's reflection characteristics and calculate the target distance. The communication node packages its own information along with the target characteristics and distance information and sends it to the network for sharing. When the communication node receives the target reflection characteristics and target distances from multiple neighboring nodes, it can use the polygonal spherical intersection positioning model and maximum likelihood estimation optimization algorithm described above to comprehensively calculate and locate the non-cooperative underwater target's position by sharing the target features and distance information, thus achieving the purpose of target detection and tracking.

[0081] The underwater positioning network can also assist cooperative targets in obtaining their own positions, achieving self-localization. The cooperative target receives information elements transmitted by multiple neighboring communication nodes. By using the transmission time of the communication nodes in the information elements and the reception time calculated using the matched field of the transmitted signals, the distance from each communication node to the target can be obtained. Using the position information of the communication nodes and their distances to the target, and employing a multilateral intersection model and maximum likelihood estimation, the optimal estimate of the cooperative target's own position can be calculated, thereby achieving self-localization.

[0082] The distributed underwater acoustic localization method and network based on the reliable propagation of information elements of communication nodes provided by the embodiments of the present invention have at least the following technical effects:

[0083] 1. The cross-verification and calculation of the communication node's own position is based on the coordinates and distances of multiple neighboring nodes, and is solved using a polygonal spherical intersection localization model, which has a low computational load. After obtaining its own position, the computational load for information element sharing and cooperative underwater target calculation is also relatively small, which helps to reduce the positioning complexity of nodes or cooperative underwater targets and reduce system power consumption;

[0084] 2. Both communication nodes and cooperative underwater targets can acquire information and calculate their own positions on their own, without the need to set up a computing center or bear the time loss of information transmission from the computing center to the target.

[0085] 3. The information of communication nodes can be dynamically updated by receiving information from neighboring nodes, and the updated location information is then broadcast. The entire underwater acoustic positioning network is therefore in a state of continuous dynamic updating. During this process, the ranging and positioning information between nodes is cross-validated and corrected. When a dynamic equilibrium is reached, the accumulated error is weakened, and the overall accuracy of the network is improved.

[0086] 4. The location information obtained by the anchor node can be shared with the underwater acoustic positioning network through the transmission mechanism designed in this invention, and the confidence of its transmission process can be evaluated, making the network more robust and stable through coupling and cross-validation between nodes.

[0087] 5. The underwater positioning network proposed in this invention adopts a decentralized architecture, in which each communication node plays its own role in the network by sharing information and performing independent calculations. This makes the positioning network very flexible and easy to expand and replace nodes.

[0088] 6. When the underwater positioning network proposed in this invention tracks and identifies underwater targets, it does not require communication nodes to report their detection signals and information to the computing center. It can automatically calculate based on its own detection results and the detection results received from neighboring nodes, providing basic information for possible maneuvers and emergency response after detection.

[0089] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A distributed underwater acoustic localization method based on reliable propagation of information elements of communication nodes, characterized in that, include: A distributed underwater acoustic positioning network is constructed by deploying several communication nodes in the exploration area, the communication nodes including anchor nodes and ordinary nodes; The information element E={L,B,D,T} of the communication node is constructed; where L is the location coordinate of the node, B is the location confidence of the node, D is the distance between the node and the node receiving data, and T is the information element update time. The anchor node obtains its position coordinates through self-localization and fills them into its own information elements; the ordinary node calculates its position coordinates and position confidence level using the information elements of multiple neighboring nodes it receives, and fills them into its own information elements. The communication node updates its own information elements periodically based on the information element update time, and transmits the updated information elements underwater as underwater acoustic signals. The ordinary node calculates its position confidence score based on the position confidence scores of multiple neighboring nodes. The formula for calculating the position confidence score is as follows: ;in, K For the propagation coefficient, B i For the first i The position confidence of each neighboring node. N The number of neighboring nodes. Z This is the bias value; Each of the communication nodes also maintains a local set of information elements M={ };in, For the information elements of the node itself, For the neighboring nodes received by this node i Information elements, i Choose from 1 to K, where K is the maximum number of neighboring nodes stored locally; The communication node uses the local set of information elements for cross-validation and location updates; the communication node propagates the local set of information elements of the node or the information elements of the node itself in the local set of information elements to various directions underwater.

2. The distributed underwater acoustic localization method based on reliable propagation of communication node information elements according to claim 1, characterized in that, The ordinary node calculates its position coordinates based on the position coordinates of multiple neighboring nodes and the distances between the ordinary node and each of the neighboring nodes, using a spherical intersection model and a maximum likelihood algorithm. The ordinary node calculates the distance between the neighboring node and the ordinary node based on the update time of the information elements in the information elements of the neighboring node and the actual time when the underwater acoustic signal corresponding to the neighboring node arrives at the ordinary node.

3. The distributed underwater acoustic localization method based on reliable propagation of communication node information elements according to claim 1, characterized in that, When updating the information elements of a common node, if the newly calculated position confidence of the common node exceeds its original value, then the newly calculated position coordinates and position confidence of the common node are used to overwrite its original value; otherwise, the position coordinates and position confidence of the common node calculated in this instance are discarded.

4. The distributed underwater acoustic localization method based on reliable propagation of communication node information elements according to claim 1, characterized in that, For any of the aforementioned communication nodes, D in the node's own information elements represents the distance between the node and itself. The value of D in the equation is 0. For any of the aforementioned communication nodes, the neighboring nodes received by that node i Information elements In this context, D represents the relationship between the node and its neighboring nodes. i The distance between them; The initial value of D in the equation is 0; This node is based on neighboring nodes. i The update time of information elements in the information elements, and neighboring nodes. i The actual arrival time of the underwater acoustic signal at the node is calculated to obtain the neighboring node's time. i The distance between the node and the value of D is then updated and replaced. For any of the communication nodes, the location confidence B of the node ranges from [0,1]; if the communication node is an anchor node, then the location confidence of the node is 1.

5. The distributed underwater acoustic localization method based on reliable propagation of communication node information elements according to claim 1, characterized in that, When the communication node maintains its local set of information elements, it fills, overwrites, or discards information elements of a new neighboring node based on preset rules after receiving such information elements. The preset rules include: if the local set of information elements is not full, then the information elements of the new neighboring node are added to the local set of information elements; if the local set of information elements is full, then it is determined whether the position confidence of the new neighboring node is higher than that of the original neighboring node, and whether the distance between the new neighboring node and the communication node is less than that between the original neighboring node and the communication node; based on the determination results, if the position confidence of the new neighboring node is higher and the distance is closer, then the information elements of the original neighboring node with lower position confidence or greater distance are replaced with the information elements of the new neighboring node; otherwise, the information elements of the new neighboring node are discarded. When the information elements of neighboring nodes in the local information element set of the communication node are updated, the local information element set is updated and the updated local information element set is propagated in all directions underwater.

6. The distributed underwater acoustic localization method based on reliable propagation of communication node information elements according to claim 1, characterized in that, The constructed distributed underwater acoustic positioning network also includes non-cooperative underwater targets and cooperative underwater targets; When detecting and tracking underwater targets, for the non-cooperative underwater target or the cooperative underwater target, a communication node calculates the position information of the underwater target based on its own information elements, the detection information obtained by the node, and the detection information obtained by multiple neighboring nodes. The detection information includes the target's reflectivity and the distance between the underwater target and the node. When the cooperative underwater target performs self-localization, it calculates the location information of the cooperative underwater target by using information elements sent by multiple nearby communication nodes.

7. A distributed underwater acoustic positioning network based on the reliable propagation of information elements from communication nodes, characterized in that, include: Several communication nodes are deployed in the exploration area, including anchor nodes and ordinary nodes; The distributed underwater acoustic positioning network based on the reliable propagation of information elements of communication nodes is used to implement the steps in the distributed underwater acoustic positioning method based on the reliable propagation of information elements of communication nodes as described in any one of claims 1-5.

8. The distributed underwater acoustic positioning network based on reliable propagation of communication node information elements according to claim 7, characterized in that, Also includes: Non-cooperative underwater targets and cooperative underwater targets; The cooperative underwater target calculates its location information using information elements sent by multiple nearby communication nodes. A communication node calculates the location information of an underwater target based on its own information elements, the detection information obtained by the node, and the detection information obtained by multiple neighboring nodes, thereby enabling the tracking and identification of the non-cooperative underwater target or the cooperative underwater target. The detection information includes the target's reflectivity and the distance between the underwater target and the node.

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