CN108226868B - Method and system for positioning cannonball water falling point - Google Patents
Method and system for positioning cannonball water falling point Download PDFInfo
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- CN108226868B CN108226868B CN201810068269.1A CN201810068269A CN108226868B CN 108226868 B CN108226868 B CN 108226868B CN 201810068269 A CN201810068269 A CN 201810068269A CN 108226868 B CN108226868 B CN 108226868B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
- G01S5/18—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using ultrasonic, sonic, or infrasonic waves
- G01S5/22—Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements
Abstract
The invention discloses a method and a system for positioning a cannonball water falling point. The method comprises the following steps: acquiring a first group of sound wave signals acquired by a first group of sonar sensors, acquiring a second group of sound wave signals acquired by a second group of sonar sensors, determining a first time difference according to the first group of sound wave signals, and determining a second time difference according to the second group of sound wave signals; determining a first arrival angle according to the first time difference and the positions of the first group of sonar sensors; determining a second arrival angle according to the second time difference and the positions of the second group of sonar sensors; and determining the position of the cannonball water falling point according to the distance difference between the first arrival angle, the second arrival angle and the monitoring point. The invention adopts the sonar array to detect the shell explosion sound wave, utilizes the majority function filter to separate single explosion data, and processes the data to determine the coordinates of the shell water falling point, thereby improving the positioning precision of the shell water falling point.
Description
Technical Field
The invention relates to the field of shipborne artillery shooting, in particular to a method and a system for positioning a cannonball water falling point.
Background
Different from a land artillery projectile landing point precision evaluation system, after a carrier-based weapon projectile falls into water, the projectile can be found quickly without any trace, the existing method for evaluating the shooting precision of the carrier-based artillery mainly depends on a camera to evaluate the position of a cannonball falling point, but the camera is easily limited by factors such as distance and weather, the coordinates of the cannonball falling point cannot be accurately obtained every time, particularly in heavy fog weather, the camera cannot clearly obtain the cannonball falling point, and large errors are easily generated.
Disclosure of Invention
The invention aims to provide a method and a system for positioning a cannonball water falling point, which are used for improving the positioning precision of the cannonball water falling point.
In order to achieve the purpose, the invention provides the following scheme:
a method of locating a projectile water drop point, the method comprising:
acquiring a first set of acoustic signals acquired by a first set of sonar sensors, the first set of acoustic signals comprising: the first and second acoustic signals, the first set of sonar sensors including: a first sonar transducer and a second sonar transducer, the first sonic signal being collected by the first sonar transducer, the second sonic signal being collected by the second sonar transducer;
acquiring a second set of acoustic signals acquired by a second set of sonar sensors, the second set of acoustic signals including: a third acoustic wave signal and a fourth acoustic wave signal, the second set of sonar sensors including: the first sonar sensor, the second sonar sensor, the third sonar sensor and the fourth sonar sensor are located on the same straight line;
determining a first time difference from the first set of acoustic signals, the first time difference being a time difference between arrival of the same explosive acoustic wave at the first sonar transducer and the second sonar transducer,
determining a second time difference from the first set of acoustic signals; the second time difference is the time difference of the same explosion sound wave reaching the third sonar transducer and the fourth sonar transducer;
determining a first arrival angle according to the first time difference and the positions of the first group of sonar sensors, wherein the first arrival angle is an included angle formed by connecting lines of three points of the cannonball water falling point, the positions of the first group of sonar sensors and the positions of the second group of sonar sensors at the positions of the first group of sonar sensors;
determining a second arrival angle according to the second time difference and the positions of the second group of sonar sensors, wherein the second arrival angle is an included angle formed by connecting lines of three points of the cannonball water falling point, the positions of the first group of sonar sensors and the positions of the second group of sonar sensors at the positions of the second group of sonar sensors;
and determining the position of the cannonball water falling point according to the distance difference between the first arrival angle, the second arrival angle and a monitoring point, wherein the distance difference of the monitoring point is the distance difference between the positions of the first set of sonar sensors and the positions of the second set of sonar sensors.
Optionally, the determining a first time difference according to the first group of sound wave signals specifically includes:
constructing a first cross-correlation function of the first acoustic signal and the second acoustic signal, the argument of the first cross-correlation function being time;
calculating a maximum of the first cross-correlation function;
determining a time value corresponding to a first value of the first cross-correlation function as the first time difference.
Optionally, the determining a second time difference according to the second group of sound wave signals specifically includes:
constructing a second cross-correlation function of the third and fourth acoustic signals, the argument of the second cross-correlation function being time;
calculating a maximum of the second cross-correlation function;
and determining the time value corresponding to the maximum value of the second cross-correlation function as the second time difference.
Optionally, the constructing a first cross-correlation function of the first acoustic signal and the second acoustic signal specifically includes:
according to the formula
Constructing the first cross-correlation function;
wherein, x (t) is the first sound wave signal, y (t) is the second sound wave signal, and τ is the first time difference.
Optionally, before determining the first time difference according to the first group of sound wave signals, the method further includes:
carrying out filtering processing on the first sound wave signal, and determining the starting moment of the first sound wave signal;
and carrying out filtering processing on the second sound wave signal, and determining the starting moment of the second sound wave signal.
Optionally, the filtering the first sound wave signal specifically includes:
converting the first acoustic signal into a digital signal;
carrying out nonlinear digital filtering processing on the digital signal, wherein the nonlinear digital filtering adopts a 6-sample window, each sample is a binary number, the first three samples represent past state variables, and the last three samples represent current state variables;
processing the current state variable and the past state variable by adopting a Boolean function to obtain a sample state, wherein the sample state comprises two binary variables;
updating the sample states in chronological order;
judging that an explosion occurs when the sample state is changed from 00 to the first 11 through one or more intermediate states, wherein the intermediate states comprise 10 and 01;
and determining the intermediate state closest to the state 11 as the starting moment of the first sound wave signal.
Optionally, the processing the current state variable and the past state variable by using a boolean function specifically includes:
outputting the binary number with the largest occurrence number in the three binary numbers in the current state variable;
and outputting the binary number with the largest occurrence number in the three binary numbers in the past state variables.
Optionally, the determining a first arrival angle according to the first time difference and the positions of the first group of sonar sensors specifically includes:
according to the formula L0Calculating a first distance, which is a distance difference between the first sonar transducer and the second sonar transducer reached by the same explosive sound wave, where L0Is a first distance, C is the speed of sound wave propagating in water, and tau is a first time difference;
according to the formula L0Calculating a first arrival angle cos α · L, where L is a distance between the first sonar sensor and the second sonar sensor, and α is the first arrival angle.
A positioning system for a projectile water drop point, the positioning system comprising:
a first acquisition module configured to acquire a first set of acoustic signals acquired by a first set of sonar sensors, the first set of acoustic signals including: the first and second acoustic signals, the first set of sonar sensors including: a first sonar transducer and a second sonar transducer, the first sonic signal being collected by the first sonar transducer, the second sonic signal being collected by the second sonar transducer;
the second acquisition module acquires a second group of sound wave signals acquired by a second group of sonar sensors, and the second group of sound wave signals include: a third acoustic wave signal and a fourth acoustic wave signal, the second set of sonar sensors including: the first sonar sensor, the second sonar sensor, the third sonar sensor and the fourth sonar sensor are located on the same straight line;
a first time difference determining module for determining a first time difference from the first set of acoustic signals, the first time difference being a time difference between arrival of the same explosive acoustic wave at the first sonar transducer and the second sonar transducer,
a second time difference determining module, configured to determine a second time difference according to the first group of sound wave signals, where the second time difference is a time difference between arrival of the same explosive sound wave at the third sonar sensor and the fourth sonar sensor;
a first arrival angle determining module, configured to determine a first arrival angle according to the first time difference and the positions of the first set of sonar sensors, where the first arrival angle is an included angle formed by connecting lines of three points, namely a cannonball water falling point, the positions of the first set of sonar sensors, and the positions of the second set of sonar sensors, at the positions of the first set of sonar sensors;
a second arrival angle determining module, configured to determine a second arrival angle according to the second time difference and the positions of the second group of sonar sensors, where the second arrival angle is an included angle formed by connecting lines of three points, namely the cannonball water falling point, the positions of the first group of sonar sensors, and the positions of the second group of sonar sensors, at the positions of the second group of sonar sensors;
and the cannonball water falling point position determining module is used for determining the position of the cannonball water falling point according to the distance difference between the first arrival angle, the second arrival angle and a monitoring point, wherein the distance difference of the monitoring point is the distance difference between the position of the first group of sonar sensors and the position of the second group of sonar sensors.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention adopts the sonar array to detect the shell explosion sound wave, utilizes the majority function filter to separate single explosion data, and processes the data to determine the coordinates of the shell water falling point, thereby improving the positioning precision of the shell water falling point.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flow chart of a method for positioning a dropping point of a cannonball of the present invention;
FIG. 2 is a diagram of the triangular relationship between the sensor array and the drop point of the projectile in accordance with the present invention;
FIG. 3 is a graph of the acoustic wave geometry of the sensor of the present invention;
fig. 4 is a block diagram of a positioning system of the cannonball water drop point of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The sonar sensor is slightly influenced by the natural environment and has a long detection distance, and the coordinates of the cannonball water falling point can be measured through reasonable sensor layout and a proper signal processing algorithm. The method is mainly based on detection of the explosion shock waves of the cannonball by a sonar array, separation of single explosion data by a majority function filter, and processing of the data to determine the coordinates of the water falling point of the cannonball.
Normally, the projectile explodes in water after falling into water, and the explosion products (existing in gas state) expand outwards at high speed to press the surrounding water medium to generate shock wave sound waves. Due to the inertia of the water stream, the explosive bubbles in the water continue to expand after the first shock wave exits, pushing the surrounding aqueous medium radially outward, causing the bubbles to "over" expand. At this time, the pressure in the bubble is lower than that of the surrounding medium, and the surrounding water starts to move reversely, i.e. to converge towards the center, so that the bubble is continuously contracted and the pressure of the bubble is gradually increased. The bubble is "over" compressed, causing the internal pressure to expand above the pressure of the surrounding medium, thus creating the first cycle of an explosive sound wave in the water. The acoustic pressure generated by the detonation of a single projectile tends to be a plurality of diminishing back-and-forth undulations. The sampling data of the explosive sound wave after the cannonball falls into water has strong irregularity and fluctuation in consideration of the interference of reflected waves generated when the shock wave propagates in water and other underwater sound noises. In the process of detecting an explosive sound source, the effective and rapid detection of when and when the explosion happens is the primary condition of the positioning analysis of the cannonball drowning point and is also the core technology of shot point positioning.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
The invention provides a method for positioning a cannonball water drop point, and fig. 1 is a flow chart of the method for positioning the cannonball water drop point, as shown in fig. 1, the method comprises the following steps:
step 101: acquiring a first set of acoustic signals acquired by a first set of sonar sensors, the first set of acoustic signals comprising: the first and second acoustic signals, the first set of sonar sensors including: a first sonar sensor and a second sonar sensor, the first sonic signal being collected by the first sonar sensor, the second sonic signal being collected by the second sonar sensor.
Step 102: acquiring a second set of acoustic signals acquired by a second set of sonar sensors, the second set of acoustic signals including: a third acoustic wave signal and a fourth acoustic wave signal, the second set of sonar sensors including: the third sound wave signal is collected by the third sonar sensor, the fourth sound wave signal is collected by the fourth sonar sensor, and the first sonar sensor, the second sonar sensor, the third sonar sensor and the fourth sonar sensor are located on the same straight line.
Step 103: determining a first time difference according to the first group of sound wave signals, wherein the first time difference is a time difference of arrival of the same explosion sound wave at the first sonar sensor and the second sonar sensor, and the method specifically includes:
step 1031: constructing a first cross-correlation function of the first acoustic signal and the second acoustic signal, the argument of the first cross-correlation function being time. In particular, according to the formula
Constructing the first cross-correlation function;
wherein, x (t) is the first sound wave signal, y (t) is the second sound wave signal, and τ is the first time difference.
Step 1032: calculating a maximum of the first cross-correlation function;
step 1033: determining a time value corresponding to a first value of the first cross-correlation function as the first time difference.
Step 104: determining a second time difference from the first set of acoustic signals; the second time difference is the time difference of the same explosion sound wave reaching the third sonar transducer and the fourth sonar transducer; the method specifically comprises the following steps:
step 1041: constructing a second cross-correlation function of the third and fourth acoustic signals, the argument of the second cross-correlation function being time;
step 1042: calculating a maximum of the second cross-correlation function;
step 1043: and determining the time value corresponding to the maximum value of the second cross-correlation function as the second time difference.
Step 105: and determining a first arrival angle according to the first time difference and the positions of the first group of sonar sensors, wherein the first arrival angle is an included angle formed by connecting lines of three points of the cannonball water falling point, the positions of the first group of sonar sensors and the positions of the second group of sonar sensors at the positions of the first group of sonar sensors.
Specifically, the method comprises the following steps: according to the formula L0Calculating a first distance, which is a distance difference between the first sonar transducer and the second sonar transducer reached by the same explosive sound wave, where L0Is a first distance, C is the speed of sound wave propagating in water, and tau is a first time difference;
according to the formula L0Calculating a first arrival angle cos α · L, where L is a distance between the first sonar sensor and the second sonar sensor, and α is the first arrival angle.
Step 106: determining a second arrival angle according to the second time difference and the positions of the second group of sonar sensors; the second arrival angle is an included angle formed by connecting lines of the cannonball water falling point, the positions of the first group of sonar sensors and the positions of the second group of sonar sensors at the positions of the second group of sonar sensors. Similarly, a second arrival angle can be obtained according to the method for obtaining the first arrival angle.
Step 107: and determining the position of the cannonball water falling point according to the distance difference between the first arrival angle, the second arrival angle and a monitoring point, wherein the distance difference of the monitoring point is the distance difference between the positions of the first set of sonar sensors and the positions of the second set of sonar sensors.
Optionally, before step 103, the method further includes:
step A1: and carrying out filtering processing on the first sound wave signal, and determining the starting moment of the first sound wave signal. The method specifically comprises the following steps:
step A11: converting the first acoustic signal into a digital signal;
step A12: carrying out nonlinear digital filtering processing on the digital signal, wherein a nonlinear filter adopts a 6-sample window, each sample is a binary number, the first three samples represent past state variables, and the last three samples represent current state variables;
step A13: processing the current state variable and the past state variable by adopting a Boolean function to obtain a sample state, wherein the sample state comprises two binary variables, and the method specifically comprises the following steps:
step A131: outputting the binary number with the largest occurrence number in the three binary numbers in the current state variable;
step A132: and outputting the binary number with the largest occurrence number in the three binary numbers in the past state variables.
Step A133: updating the sample states in chronological order;
step A134: judging that an explosion occurs when the sample state is changed from 00 to the first 11 through one or more intermediate states, wherein the intermediate states comprise 10 and 01;
step A135: and determining the intermediate state closest to the state 11 as the starting moment of the first sound wave signal.
Step A2: and carrying out filtering processing on the second sound wave signal, and determining the starting moment of the second sound wave signal.
The invention mainly solves the problem of locating the cannonball drop point coordinates from the following points: detection and separation of explosive sound waves; measuring the direction angle of an explosion sound source; and calculating the coordinates of the cannonball water falling point.
1. Detection and separation of explosive sound waves
Artillery shooting performance tests usually have multiple continuous shots, and in order to effectively evaluate shooting accuracy, the drop points of each artillery shell need to be measured and positioned one by one, so that when explosion happens is detected in a data sequence continuously measured by a sensor, and sound wave data generated by explosion of a single artillery shell is separated. In order to separate the sound wave data of each cannonball, a reasonable sound pressure threshold needs to be set, under an ideal condition (without considering disturbance), when the amplitude of the sampling data is larger than the threshold, the cannonball falls into water and explodes, and when the amplitude of the sampling data is smaller than the threshold, the cannonball falls into water and explodes. A comparator is designed for this purpose, the sampling data is compared with a comparator threshold value in real time, binary data is output, explosion is considered to occur when the output waveform of the comparator changes from low to high (the logic level changes from 0 to 1), and the explosion sound wave is considered to be ended when the output waveform of the comparator changes from high to low (1 changes to 0). And effective data of single shell explosive sound waves can be separated according to the high level starting and stopping time output by the comparator. The separation of the explosion sound wave data not only reduces the influence of noise on the detection performance, but also can reduce the influence generated by adjacent explosion sound waves, and then accurately positions the shot point falling position.
Due to the fluctuation characteristics of the explosion sound source and the existence of other underwater sound interference, the corresponding sampling data near the explosion occurrence and termination time point has large fluctuation, and meanwhile, the filtering algorithm for separating single explosion sound wave data needs to consider both small time delay and separation accuracy, so that a filter needs to be added behind a comparator. The method adopts a majority function filtering method to detect the starting and stopping time of shell explosion, and further separates single explosion data one by one and determines the position of a shot point. The main advantage of the majority function filter is that the output time delay of the filter is fixed and controllable to a smaller range, while the operation speed is faster.
The majority function is a non-linear digital filter, a boolean function that takes n binary numbers as input and returns the number of those numbers that appears the most. Assuming that there are 3 Boolean inputs, then the value it returns corresponds to a number that appears at least 2 times (true or false), in which case the 2 equal values account for 66% of the total. The majority function always returns the majority (> 50%) of the total number with the logical operation:
Majority＝(A∧B)∨(A∧C)∨(B∧C)；
for example, if the comparator output sequence is 101(a is 1, B is 0, and C is 1), then the Majority is 1, and if the comparator output sequence 001(a is 0, B is 0, and C is 1), then the Majority is 0.
In order to realize the start-stop moment detection of explosion data, the nonlinear filter adopts a 6-sample window, each three samples represent a state, and for this purpose, A, B, C, D, E, F six binary memory variables are designed to be used as comparator output data storage units, wherein A, B, C three variables can be regarded as past state variables, and D, E, F can be regarded as current state variables. When new comparator data is generated, the data is sent to F, the data of F is sent to E, the data of E is sent to D, and so on, the data of B is sent to A, and finally the data overflow in A is abandoned. The past state A, B, C and the current state D, E, F are logically operated by the formula (1.1), respectively, and logical values of the current state (S-NEW) and the past state (S-OLD) are determined. For example, when the ABCDEF binary bit is in the state 001010, S-OLD is 0, and S-NEW is 0, which indicates that the NEW and OLD states are all 0 and no explosive sound wave is generated; if the output logic of the comparator at the second sampling moment is 1, the ABCDEF binary bit is changed into 010 and 101, the S-OLD is 0, the S-NEW is 1, and the state is changed from low to high, which indicates that the possible explosive sound wave is just generated; if the output logic of the comparator at the third sampling moment is still 1, the ABCDEF binary bit is changed to 101, 011, S-OLD is 1, S-NEW is 1, and the state is always high, which indicates that the explosive sound wave continuously exists; if the output logic of the comparator at the fourth sampling time is 0, the ABCDEF bit is changed to 010, 110, S-OLD is 0, S-NEW is 1, and the determination is ambiguous. For this purpose, the following rules are established (S-OLD ═ 0, S-NEW ═ 1, which reduces to state 0-1, the rising edge indicating that an explosion is likely to occur, S-OLD ═ 1, S-NEW ═ 0, which reduces to state 1-0, the falling edge indicating that an explosion is likely to end, S-OLD ═ 0, S-NEW ═ 0, which reduces to state 0-0, the double low logic indicating that no explosion occurs, S-OLD ═ 1, S-NEW ═ 1, which reduces to state 1-1, the double high logic indicating that an explosion has occurred):
(1) setting the current state to be 0-0 for judging the initial moment of explosion occurrence, and if the state of the next moment is 0-1, indicating that the explosion is possible to occur; if the state is 1-0 at the next time, the interference state is indicated. It is believed that the explosion should occur from state 0-0 through one or more intermediate states (0-1 or 1-0) to the occurrence of the first 1-1 state, with the start time being based on the time of the intermediate state closest to the 1-1 state.
(2) Setting the current state to be 1-1 for judging the explosion occurrence end time, and if the next state is 1-0, indicating that the explosion is probably ended; if the state is 0-1 at the next time, the interference state is indicated. It is generally believed that the end of the explosion should occur from state 1-1 through an intermediate state (0-1 or 1-0) to the first 0-0 state, with the end time being based on the intermediate state time closest to the 0-0 state.
According to the above judgment criteria, the majority function filter can determine the starting and stopping time of the single explosion, thereby separating the sampling data of the single explosion sound wave. This has two advantages: firstly, the interference of adjacent explosion sound wave data to the explosion positioning analysis can be avoided; and secondly, the influence caused by invalid noise can be reduced, and the signal to noise ratio is favorably improved. And each sonar sensor continuously samples data, effective data are separated through a majority function, and then the microprocessor analyzes the data, judges the arrival angle of the sound wave and calculates the coordinates of the explosion sound source according to the triangular relation.
2. Explosive source direction angle measurement
In the patent, sound source positioning is solved based on a triangular relation formed by a sensor array and a cannonball drop point, and the working principle of the sound source positioning is shown in figure 2. At two places on the coast or on the measuring hull at a distance R3T 2 (x)2,y2) Point sum T3 (x)3,y3) The point set sensor array, knowing that the distance between the points T2 and T3 is R3, has coordinates (x)2,y2) And (x)3,y3) The positioning can be accurately performed by a GPS. Two sonar sensors A and B are respectively installed at a point T2, and the spacing distance is L; two sonar sensors C and D are respectively installed at a point T3, and the interval distance is L; the four ABCD sensors are arranged on a straight line; let the cannonball water drop point T1 coordinate be (x)1,y1) And is not known. When the cannonball falls into water and explodes, sound waves propagate outwards from a point T1, a point T2 and a point T3 are provided with sensor arrays for receiving in real time, a triangle is formed by a point T1, a point T2 and a point T3, and if arrival angles alpha and beta of the explosive sound waves reaching the point T2 and the point T3 can be measured, the coordinates of the point T1 can be obtained. The sound wave at the point T1 is retransmitted in a spherical wave, and if the distance from the sound source to the sensor is far and the distance can be regarded as a far field, the sound waves obtained by the two sensors at the point T2 or the point T3 are parallel, that is, the arrival angles alpha of the two points A, B are the same, and the arrival angles beta of the sound waves at the two points C, D are the same in the same manner. For this purpose, angles of arrival α and β are first of all required.
Let signals received by A, B be X (T), Y (T), and let sound source signals near the point T1 be s (T). Since A, B are located at close distance and in almost the same working environment, there is only one time delay τ between the X (t) and Y (t) signals0I.e. X (t) s (t- τ)0) Y (t) s (t), transducer acoustic geometry such asFig. 3. By utilizing the single explosion sound wave signals separated by the majority function method, the sound wave data obtained by A, B two-point sensors except the existence of the time delay tau can be known0The outer is almost the same. The cross-correlation function R of the signals X (t), Y (t) is obtained by signal processing theoryXY(τ)：
According to the theory of cross-correlation, only if τ is τ0Time, cross correlation function RXY(τ) reaches a maximum value. Comparing cross-correlation functions R by searchingXY(τ) find the difference in the time at which the explosive sound wave reaches A, B. If the speed of sound wave in water is C m/s, the difference of distance from the sound wave to the sensor array is L0L is obtained from the triangular relation ═ C · τ0Further, the angle of arrival α can be obtained as cos α · L. And the arrival angle beta is obtained by the same method.
The correlation function is a description of the degree of correlation between the values of the signals x (t), y (t), which may be random or deterministic, at any two different times t1, t 2. In general terms, the degree of similarity between signals is large if two time series are emitted from the same sound source and arrive at two sensors at the same time, and in this context, the time until the sound source arrives at the sensors is different, such as x first, y arrives delayed by t seconds, and the samples of the time series are the same time base, and although they are emitted from the same sound source, x (1) is not similar to y (1), x (2) is not similar to y (2) … x (n) is not similar to y (n), and the correlation function value is small. Then x (t +1) and y (1), x (t +2) and y (2) … x (t + n) and y (n) are similar to each other only after delaying the x time sequence by t seconds, and the correlation function value is the largest. Another reason for using a correlation function to find the time difference between the arrival of the same signal at different sensors is that any sensor is affected by noise, which is usually different from sensor to sensor, and the correlation function is small (theoretically zero). Even with the same noise, the correlation function of the noise is theoretically zero as long as the delay t is not equal to zero. This reduces the effect of noise on the measurement.
3. Computing the coordinates of the drop point of a projectile
If two arrival angles alpha and beta are obtained, and the distance R3 between the T2 point and the T3 point of the sensor array is arranged, the coordinates of the cannonball water falling point can be obtained by utilizing the relation of the figure 2.
If the vertical distance from the shell water falling point to the shore is h, h is equal to L1tanα＝L2tan β. Known as R3 ═ L1+L2H and L can be obtained1And L2A value of (b), then x1＝x2+L1,y1＝y2+ h. The coordinate (x) of the dropping point T1 of the cannonball can be obtained1，y1)。
The invention adopts the sonar array to detect the shell explosion sound wave, utilizes the majority function filter to separate single explosion data, and processes the data to determine the coordinates of the shell water falling point, thereby improving the positioning precision of the shell water falling point.
The invention also provides a positioning system of the cannonball water drop point, and figure 4 is a structural diagram of the positioning system of the cannonball water drop point. As shown in fig. 4, the positioning system includes:
a first obtaining module 401, configured to obtain a first set of acoustic signals collected by a first set of sonar sensors, where the first set of acoustic signals includes: the first and second acoustic signals, the first set of sonar sensors including: a first sonar transducer and a second sonar transducer, the first sonic signal being collected by the first sonar transducer, the second sonic signal being collected by the second sonar transducer;
a second acquiring module 402, configured to acquire a second set of acoustic signals acquired by a second set of sonar sensors, where the second set of acoustic signals includes: a third acoustic wave signal and a fourth acoustic wave signal, the second set of sonar sensors including: the first sonar sensor, the second sonar sensor, the third sonar sensor and the fourth sonar sensor are located on the same straight line;
a first time difference determining module 403, configured to determine a first time difference according to the first group of sound wave signals, where the first time difference is a time difference between arrival of the same explosive sound wave at the first sonar sensor and the second sonar sensor,
a second time difference determination module 404, configured to determine a second time difference according to the first set of acoustic signals; the second time difference is the time difference of the same explosion sound wave reaching the third sonar transducer and the fourth sonar transducer;
a first angle-of-arrival determination module 405, configured to determine a first angle-of-arrival according to the first time difference and the positions of the first set of sonar sensors; the first arrival angle is an included angle formed by connecting lines of three points of a cannonball water falling point, the positions of the first group of sonar sensors and the positions of the second group of sonar sensors at the positions of the first group of sonar sensors;
a second arrival angle determination module 406, configured to determine a second arrival angle according to the second time difference and the positions of the second set of sonar sensors; the second arrival angle is an included angle formed by connecting lines of the cannonball water falling point, the positions of the first group of sonar sensors and the positions of the second group of sonar sensors at the positions of the second group of sonar sensors;
a location determining module 407 of the cannonball water falling point, configured to determine a location of the cannonball water falling point according to the distance difference between the first arrival angle, the second arrival angle, and the monitoring point; and the distance difference of the monitoring points is the distance difference between the positions of the first set of sonar sensors and the positions of the second set of sonar sensors.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (7)
1. A method for positioning a cannonball water drop point is characterized by comprising the following steps:
acquiring a first set of acoustic signals acquired by a first set of sonar sensors, the first set of acoustic signals comprising: the first and second acoustic signals, the first set of sonar sensors including: a first sonar transducer and a second sonar transducer, the first sonic signal being collected by the first sonar transducer, the second sonic signal being collected by the second sonar transducer;
acquiring a second set of acoustic signals acquired by a second set of sonar sensors, the second set of acoustic signals including: a third acoustic wave signal and a fourth acoustic wave signal, the second set of sonar sensors including: the first sonar sensor, the second sonar sensor, the third sonar sensor and the fourth sonar sensor are located on the same straight line;
determining a first time difference from the first set of acoustic signals, the first time difference being a time difference between arrival of the same explosive acoustic wave at the first sonar transducer and the second sonar transducer,
determining a second time difference from the first set of acoustic signals; the second time difference is the time difference of the same explosion sound wave reaching the third sonar transducer and the fourth sonar transducer;
determining a first arrival angle according to the first time difference and the positions of the first group of sonar sensors, wherein the first arrival angle is an included angle formed by connecting lines of three points of the cannonball water falling point, the positions of the first group of sonar sensors and the positions of the second group of sonar sensors at the positions of the first group of sonar sensors;
determining a second arrival angle according to the second time difference and the positions of the second group of sonar sensors, wherein the second arrival angle is an included angle formed by connecting lines of three points of the cannonball water falling point, the positions of the first group of sonar sensors and the positions of the second group of sonar sensors at the positions of the second group of sonar sensors;
determining the position of a cannonball water falling point according to the distance difference between the first arrival angle, the second arrival angle and a monitoring point, wherein the distance difference of the monitoring point is the distance difference between the positions of the first set of sonar sensors and the positions of the second set of sonar sensors;
prior to said determining a first time difference from said first set of acoustic signals, further comprising:
carrying out filtering processing on the first sound wave signal, and determining the starting moment of the first sound wave signal;
carrying out filtering processing on the second acoustic signal, and determining the starting moment of the second acoustic signal;
the filtering processing of the first sound wave signal specifically includes:
converting the first acoustic signal into a digital signal;
carrying out nonlinear digital filtering processing on the digital signal, wherein the nonlinear digital filtering adopts a 6-sample window, each sample is a binary number, the first three samples represent past state variables, and the last three samples represent current state variables;
processing the current state variable and the past state variable by adopting a Boolean function to obtain a sample state, wherein the sample state comprises two binary variables;
updating the sample states in chronological order;
judging that an explosion occurs when the sample state is changed from 00 to the first 11 through one or more intermediate states, wherein the intermediate states comprise 10 and 01;
and determining the intermediate state closest to the state 11 as the starting moment of the first sound wave signal.
2. The method according to claim 1, wherein determining the first time difference from the first set of acoustic signals comprises:
constructing a first cross-correlation function of the first acoustic signal and the second acoustic signal, the argument of the first cross-correlation function being time;
calculating a maximum of the first cross-correlation function;
determining a time value corresponding to a first value of the first cross-correlation function as the first time difference.
3. The method according to claim 1, wherein determining a second time difference from the second set of acoustic signals comprises:
constructing a second cross-correlation function of the third and fourth acoustic signals, the argument of the second cross-correlation function being time;
calculating a maximum of the second cross-correlation function;
and determining the time value corresponding to the maximum value of the second cross-correlation function as the second time difference.
4. The method according to claim 2, wherein the constructing a first cross-correlation function of the first acoustic signal and the second acoustic signal comprises:
according to the formula
Constructing the first cross-correlation function;
wherein, x (t) is the first sound wave signal, y (t) is the second sound wave signal, and τ is the first time difference.
5. The method according to claim 1, wherein the processing the current state variable and the past state variable by using a boolean function specifically includes:
outputting the binary number with the largest occurrence number in the three binary numbers in the current state variable;
and outputting the binary number with the largest occurrence number in the three binary numbers in the past state variables.
6. The method according to claim 1, wherein the determining a first angle of arrival from the first time difference and the positions of the first set of sonar sensors specifically comprises:
according to the formula L0Calculating a first distance, which is a distance difference between the first sonar transducer and the second sonar transducer reached by the same explosive sound wave, where L0Is a first distance, C is the speed of sound wave propagating in water, and tau is a first time difference;
according to the formula L0Calculating a first arrival angle cos α · L, where L is a distance between the first sonar sensor and the second sonar sensor, and α is the first arrival angle.
7. A positioning system for a projectile water drop point, the positioning system comprising:
a first acquisition module configured to acquire a first set of acoustic signals acquired by a first set of sonar sensors, the first set of acoustic signals including: the first and second acoustic signals, the first set of sonar sensors including: a first sonar transducer and a second sonar transducer, the first sonic signal being collected by the first sonar transducer, the second sonic signal being collected by the second sonar transducer;
the second acquisition module acquires a second group of sound wave signals acquired by a second group of sonar sensors, and the second group of sound wave signals include: a third acoustic wave signal and a fourth acoustic wave signal, the second set of sonar sensors including: the first sonar sensor, the second sonar sensor, the third sonar sensor and the fourth sonar sensor are located on the same straight line;
a first time difference determining module for determining a first time difference from the first set of acoustic signals, the first time difference being a time difference between arrival of the same explosive acoustic wave at the first sonar transducer and the second sonar transducer,
a second time difference determining module, configured to determine a second time difference according to the first group of sound wave signals, where the second time difference is a time difference between arrival of the same explosive sound wave at the third sonar sensor and the fourth sonar sensor;
a first arrival angle determining module, configured to determine a first arrival angle according to the first time difference and the positions of the first set of sonar sensors, where the first arrival angle is an included angle formed by connecting lines of three points, namely a cannonball water falling point, the positions of the first set of sonar sensors, and the positions of the second set of sonar sensors, at the positions of the first set of sonar sensors;
a second arrival angle determining module, configured to determine a second arrival angle according to the second time difference and the positions of the second group of sonar sensors, where the second arrival angle is an included angle formed by connecting lines of three points, namely the cannonball water falling point, the positions of the first group of sonar sensors, and the positions of the second group of sonar sensors, at the positions of the second group of sonar sensors;
the position determining module of the cannonball water falling point is used for determining the position of the cannonball water falling point according to the distance difference between the first arrival angle, the second arrival angle and a monitoring point, wherein the distance difference of the monitoring point is the distance difference between the position of the first group of sonar sensors and the position of the second group of sonar sensors;
prior to said determining a first time difference from said first set of acoustic signals, further comprising:
carrying out filtering processing on the first sound wave signal, and determining the starting moment of the first sound wave signal;
carrying out filtering processing on the second acoustic signal, and determining the starting moment of the second acoustic signal;
the filtering processing of the first sound wave signal specifically includes:
converting the first acoustic signal into a digital signal;
carrying out nonlinear digital filtering processing on the digital signal, wherein the nonlinear digital filtering adopts a 6-sample window, each sample is a binary number, the first three samples represent past state variables, and the last three samples represent current state variables;
processing the current state variable and the past state variable by adopting a Boolean function to obtain a sample state, wherein the sample state comprises two binary variables;
updating the sample states in chronological order;
judging that an explosion occurs when the sample state is changed from 00 to the first 11 through one or more intermediate states, wherein the intermediate states comprise 10 and 01;
and determining the intermediate state closest to the state 11 as the starting moment of the first sound wave signal.
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| CN108981481B (en) * | 2018-09-06 | 2020-05-12 | 北京航天控制仪器研究所 | Target-off-target measuring system for target ship on lake |
| CN110048783B (en) * | 2019-04-19 | 2021-01-01 | 美钻深海能源科技研发（上海）有限公司 | Sound wave communication unit, system, base station, inspection device and sound wave communication method |
| CN110333540A (en) * | 2019-07-09 | 2019-10-15 | 中科传启（苏州）科技有限公司 | A kind of life body detecting method, equipment and automobile data recorder |
| CN110333541A (en) * | 2019-07-09 | 2019-10-15 | 中科传启（苏州）科技有限公司 | A kind of life body detecting method, equipment and automobile data recorder |
| CN112147577B (en) * | 2020-09-27 | 2024-03-29 | 中国科学院上海微系统与信息技术研究所 | Explosion target passive positioning system and method based on seismic wave feature analysis |
| CN114397913B (en) * | 2021-12-15 | 2023-12-12 | 中国人民解放军军事科学院国防科技创新研究院 | Rocket debris searching and positioning system and method |
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