阅读说明：本技术 基于矢量水听器技术的水下无人集群导航定位方法 (Underwater unmanned cluster navigation positioning method based on vector hydrophone technology ) 是由 王燕 洪连进 方尔正 于 2021-07-30 设计创作，主要内容包括：本发明提供一些基于矢量水听器技术的水下无人集群导航定位方法,包括,集群系统中的主节点的发射声源和精确导航系统作为导航信息来源；主节点、被动节点完成时间同步设定；在集群航行过程中主节点按照2秒1次的重复周期发射含有信息的声脉冲信号；集群航行器中的被动节点接收到主节点发射的声信号后进行分析处理,通过声脉冲信号解算出自身与主节点的相对方位和距离；通过声脉冲信号获取当前要保持的编队形式；将获得方位和距离信息合并后取得绝对大地坐标；被动节点计算偏航后,按照编队形式调整自身相对主节点的位置,实现编队保持。本发明中提供了完善的水下声学导航手段和编队能力,功能完善、定位精度高、使用方便等优点。(The invention provides underwater unmanned cluster navigation positioning methods based on a vector hydrophone technology, which comprise that a transmitting sound source of a main node in a cluster system and an accurate navigation system are used as navigation information sources; the master node and the passive node finish time synchronization setting; in the process of cluster navigation, a main node transmits an acoustic pulse signal containing information according to a repetition period of 1 time 2 seconds; the passive nodes in the cluster aircraft receive the acoustic signals transmitted by the main node and then analyze and process the signals, and the relative direction and distance between the passive nodes and the main node are calculated through the acoustic pulse signals; acquiring a formation form to be kept currently through an acoustic pulse signal; combining the obtained azimuth and distance information to obtain absolute geodetic coordinates; and after the passive node calculates the yaw, adjusting the position of the passive node relative to the main node according to a formation form, and realizing formation maintenance. The invention provides a perfect underwater acoustic navigation means and formation capability, and has the advantages of perfect function, high positioning precision, convenient use and the like.)

1. The underwater unmanned cluster navigation positioning method based on the vector hydrophone technology is characterized by comprising the following steps of:

the method comprises the following steps: the emission sound source of the main node in the cluster system and the accurate navigation system are used as navigation information sources;

step two: the master node and the passive node finish time synchronization setting;

step three: in the process of cluster navigation, a main node transmits an acoustic pulse signal containing information according to a repetition period of 1 time 2 seconds;

step four: the passive nodes in the cluster aircraft receive the acoustic signals transmitted by the main node and then analyze and process the signals, and the relative direction and distance between the passive nodes and the main node are calculated through the acoustic pulse signals;

step five: acquiring a formation form to be kept currently through an acoustic pulse signal;

step six: combining the azimuth information and the distance information obtained after the step four to obtain absolute geodetic coordinates;

step seven: and after the passive node calculates the yaw, adjusting the position of the passive node relative to the main node according to a formation form, and realizing formation maintenance.

2. The method according to claim 1, wherein the ping signal in step three comprises two parts, the first part is a ranging pulse and the second part is a command encoding pulse.

3. The underwater unmanned cluster navigation and positioning method based on the vector hydrophone technology as claimed in claim 2, wherein in the fourth step, the relative azimuth and distance between the underwater unmanned cluster navigation and positioning method and the main node are calculated through the ranging pulse of the first part.

4. The underwater unmanned cluster navigation and positioning method based on the vector hydrophone technology as claimed in claim 2, wherein in the fifth step, the formation form to be currently maintained is obtained through the instruction encoding pulse of the second part.

5. The underwater unmanned cluster navigation and positioning method based on the vector hydrophone technology as claimed in claim 1, wherein in the analysis processing in the fourth step, a vector orientation estimation algorithm is adopted when the passive node calculates the orientation of the master node.

6. The underwater unmanned cluster navigation and positioning method based on the vector hydrophone technology as claimed in claim 5, wherein the vector direction estimation method is as follows: the vector hydrophone can simultaneously obtain the sound pressure P of the sound signal transmitted by the main node, the X-axis vibration velocity Vx and the Y-axis vibration velocity Vy, wherein the sound pressure P is a scalar, the Vx and the Vy are vectors, after the power spectrum operation, a sound intensity vector can be obtained, the X-axis sound intensity Ix is P multiplied by Vx, the Y-axis sound intensity Iy is P multiplied by Vy, and the relative position of the main node and the passive node is as follows:

θ＝atan(Iy/Ix)。

7. the underwater unmanned cluster navigation and positioning method based on the vector hydrophone technology as claimed in claim 6, wherein when the passive node is far away from the master node to execute the task and then returns to the vicinity of the master node to carry out formation navigation again, vector direction estimation is adopted, the passive node remotely detects the ranging pulse broadcasted by the master node, and maneuvers to the vicinity of the master node after obtaining the direction.

Technical Field

The invention relates to the field of navigation and positioning of an underwater unmanned system, in particular to an underwater unmanned cluster navigation and positioning method based on a vector hydrophone technology.

Background

The appearance of the vector hydrophone is known as the revolution of the underwater acoustic technology, and compared with the traditional acoustic pressure hydrophone, the vector hydrophone can obtain more comprehensive sound field information in an underwater sound field, including displacement, vibration speed, acceleration, acoustic pressure gradient and the like of water particles. Nowadays, the technology of the vector hydrophone of the vibration velocity, the acceleration and the sound pressure gradient type tends to be mature, and the vector hydrophone has wide application in various fields of underwater sound. The principle and the method for navigating and positioning the underwater unmanned cluster are that when the underwater unmanned vehicle cannot obtain a radio navigation positioning signal due to the skin effect of seawater and cannot adopt a large-scale inertial navigation system due to energy load and the like, an acoustic method for navigating the underwater unmanned cluster is completed by adopting a vector hydrophone and a vector signal processing method. Navigation and positioning of an underwater unmanned cluster are key problems of the underwater UUV cluster, and currently, underwater cluster navigation adopting a vector hydrophone acoustic principle is not researched, and is still in a starting stage.

In the traditional underwater unmanned cluster navigation positioning method, inertial navigation and ultra-short baseline navigation are available. The inertial navigation cost is high, the accumulated error is large, and the cost of each unmanned node using a high-cost inertial navigation system cannot be borne. The ultrashort baseline acoustic navigation method has the advantages that only the master station can acquire the position information of the positioned node, but the passive node cannot acquire the relative position and the absolute position of the passive node and the master node, and the defect is obvious. The small unmanned cluster system can also use master-slave navigation, namely a master node carries high-precision navigation equipment, slave nodes communicate with the master node and position information is acquired through an acoustic system, but the method has the key point of accurately acquiring the position relation of the master node and the slave nodes, but the cluster system cannot carry a large-aperture sonar array, and the precision of the method cannot be guaranteed. In summary, there is an urgent need to develop a new underwater unmanned cluster navigation positioning method.

In recent years, UUV-type underwater unmanned clusters are gradually valued by various countries. Research on underwater unmanned clusters is carried out at home and abroad to a certain extent. The defects of inertial navigation and ultra-short baseline underwater acoustic navigation are not repeated, a typical document of master-slave multi-unmanned underwater vehicle collaborative navigation positioning research based on underwater acoustic propagation delay (military science report 2009, 12 th period p1674-1678) is different from the realization principle of the invention, and the biggest problem exists in that by adopting the method in the text, navigation positioning errors of hundreds of meters can be generated within a few minutes even after post-filtering processing is used, and as can be seen from the text and the drawing 4, the positioning errors can reach 100m within less than 1200 seconds, and are increasingly large along with the increase of time, and the errors can not be tolerated in the application of cluster formation navigation.

Disclosure of Invention

The invention aims to provide an underwater unmanned cluster navigation and positioning method based on a vector hydrophone technology for an underwater unmanned cluster system, which can enable passive nodes in a formation to accurately acquire the position information of a main node and complete absolute position acquisition of formation form retention capacity under the guidance of an active node.

The underwater unmanned cluster navigation positioning method based on the vector hydrophone technology is an underwater cluster navigation method which can be completed only by taking the vector hydrophone as a core, and has the principle that equipment works underwater and comprises a main node and a plurality of passive nodes, and in order to improve the reliability of a system, one passive node can be arranged to carry equipment with the same function as the main node as a backup main node; the main node transmits broadband sound wave signals, the passive node acquires the sound signals by adopting a vector receiving hydrophone and then obtains high-precision direction finding and distance measuring results which can be obtained by a large sonar array by adopting a vector signal processing algorithm, the relative direction and distance between the passive node and the main node are calculated according to the results, then the main node transmits sound communication signals to broadcast self position information and instruction codes, and the passive node receives the signals and then resolves to obtain the self true direction and the next motion element. When the passive node is far away from the main node for operation, the main node can send a guiding signal, and the passive node can return to the vicinity of the main node for re-formation after receiving the guiding signal. The system has the characteristics of high positioning and navigation precision, long retrieval distance and capability of autonomously acquiring relative positions to keep formation.

The specific technical scheme is as follows:

an underwater unmanned cluster navigation positioning method based on a vector hydrophone technology comprises the following steps:

the method comprises the following steps: the emission sound source of the main node in the cluster system and the accurate navigation system are used as navigation information sources;

step two: the master node and the passive node finish time synchronization setting;

step three: in the process of cluster navigation, a main node transmits an acoustic pulse signal containing information according to a repetition period of 1 time 2 seconds, wherein the signal consists of two parts, the first part is a ranging pulse, and the second part is an instruction coding pulse;

step four: the passive nodes in the cluster aircraft receive the acoustic signals transmitted by the main node and then analyze and process the acoustic signals, and the relative azimuth and distance between the passive nodes and the main node are calculated through the ranging pulse of the first part;

step five: acquiring a formation form to be kept currently through the instruction coding pulse of the second part;

step six: combining the azimuth information and the distance information obtained after the step four to obtain absolute geodetic coordinates;

step seven: and after the passive node calculates the yaw, adjusting the position of the passive node relative to the main node according to a formation form, and realizing formation maintenance.

And step four, analyzing and processing, wherein a vector orientation estimation algorithm is adopted when the passive node calculates the orientation of the master node.

The vector direction estimation method in the fourth step comprises the following steps: the vector hydrophone can simultaneously obtain the sound pressure P of the sound signal transmitted by the main node, the X-axis vibration velocity Vx and the Y-axis vibration velocity Vy, wherein the sound pressure P is a scalar, the Vx and the Vy are vectors, after the power spectrum operation, a sound intensity vector can be obtained, the X-axis sound intensity Ix is P multiplied by Vx, the Y-axis sound intensity Iy is P multiplied by Vy, and the relative position of the main node and the passive node is as follows: θ is atan (Iy/Ix).

When the passive node is far away from the main node to execute the task and then needs to return to the vicinity of the main node to carry out formation navigation again, the steps can still be adopted, and the passive node only needs to remotely detect the ranging pulse broadcasted by the main node to maneuver to the vicinity of the main node after obtaining the direction.

The underwater unmanned cluster navigation positioning method provides a perfect underwater acoustic navigation means and formation capability for the existing underwater unmanned cluster navigation, has the advantages of perfect functions, high positioning precision, convenient use and the like compared with the existing navigation positioning method for the underwater unmanned cluster, and can be used for the underwater cluster navigation positioning. Fills the blank of the field in China.

The invention has the advantages that:

1. in the invention, each passive node can obtain the relative position between the passive node and the main node through vector acoustic information calculation, has high precision, and can judge the state of the passive node in the process of queuing by the main node information.

2. Each passive node can obtain the distance between the passive node and the main node through the calculation of acoustic information.

3. Each passive node can adjust the position through the acoustic instruction to realize the invariance of the formation queue shape.

4. The main node and the backup main node can improve the fault tolerance rate and the use efficiency of the system.

Drawings

FIG. 1 is a functional block diagram of the present invention;

FIG. 2 is an information processing flow diagram of the present invention;

FIG. 3 is a simulation graph of SNR and TD for an example.

Detailed Description

The specific technical scheme of the invention is described by combining the embodiment.

The technical principle of the present invention is as shown in fig. 1, and the master node in fig. 1 transmits a broadband sound wave signal, which has a time synchronization signal as a starting point and contains position information and instruction information. After receiving the acoustic signals, the passive nodes 1-n adopt a vector signal processing algorithm to calculate a plurality of parameters, mainly comprising relative directions and relative distances with the main node, and decoding the position information and instruction codes of the main node. The sound information of the main node is output from the transmitting transducer, and all the sound information adopts a broadcasting mode. Vector hydrophones are adopted for receiving passive node acoustic information, the directivity of the hydrophones is irrelevant to the frequency, and high directional precision which can be obtained only by a large-aperture sonar array can be realized. No matter what kind of acoustic information the master node sends, the method can be used for high-precision direction finding. The lower bound of the direction-finding precision of the Kolamivudine is as follows:

wherein: m is the number of samples, BT (time-bandwidth product),is pitch angle and SNR is signal to noise ratio. From the formula, when the aircrafts in the cluster are in the same plane, the high bandwidth of the broadcast signal of the main node and the high communication signal-to-noise ratio can bring great benefits to the direction finding of the vector hydrophone, so that the direction finding precision of the passive node is high, the positioning precision of less than 1% R (R is the distance between two nodes) can be obtained, the generality is not lost, and when R is 500m, the positioning error is less than 5 m. This is incomparable with other underwater acoustic systems that use master-slave navigation.

The signal adopted by the system is divided into two types, namely a broadcast signal for the formation travelling and operation, and the broadcast signal is transmitted by prefix and simple information. The prefix is used for synchronous ranging, and the following acoustic signals are used for information transmission and instruction. And after the relative direction and the absolute distance between the passive node and the main node are obtained, the self absolute position of the passive node can be calculated through the self position broadcasted by the main node, so that the formation maintenance is finished. The second signal is a guide signal broadcasted by the main node, the guide signal is used for guiding the passive node, and after the passive node receives the signal, the passive node obtains the main node direction by means of the frequency-independent directivity and spatial gain and then returns to the vicinity of the main node to be re-queued.

The flow of the method is shown in fig. 2, a main node emits an acoustic pulse signal under the guidance of a time synchronization signal, the signal is transmitted through a water medium and then received by a vector hydrophone of a passive node in a formation, the received signal result is conditioned and digitized and then subjected to three processes, the first process is vector azimuth calculation, and the passive node can obtain an accurate relative azimuth with the main node through a vector signal processing algorithm. The second processing is that the passive node can obtain the accurate arrival time of the acoustic pulse signal transmitted by the main node by a matched filtering method under the coordination of the synchronous signal, and further the distance between the passive node and the main node can be obtained by sound velocity calculation. The third process is to solve the broadcast information sent by the main node, and the information contains the geodetic coordinates and the instruction codes of the main node. After the three processes, the passive node has fully acquired the position of the passive node, the relative position with the master node, formation information and the like, and the passive node can be guided to activate and complete formation maintenance through the information.

The simulation result of this example is shown in fig. 3.

The test condition parameters are as follows: the sound source frequency f0 is 2.5kHz, and the emission sound source level SL is 140dB (re 1 μ Pa @1 m). Simulation calculation is carried out according to sonar equation in water sound principle of R.J Youlek, and the propagation loss TL is 20lgR 54dB and the environmental noise spectrum level at 2.5kHz is 58dB, so that the signal-to-noise ratio SNR is 140-54-58 is 28dB, and the working distance R is 500 m. And calculating through the lower bound of CR to obtain the relation between the input signal-to-noise ratio and the azimuth estimation deviation in the figure 2. It can be seen from the figure that an input signal-to-noise ratio of 0dB can guarantee an azimuth estimation accuracy of 1 ° with a sufficient margin left.

Therefore, under the sound source level of 140dB, the direction finding precision within 500m can be ensured to be 1 degree. Therefore, the displacement error Δ < 500 × sin (1 °) is 8.7 m.