A continuous active sonar target ranging method

Abstract

The application discloses a kind of continuous active sonar target ranging method, method includes the following steps: step 1, the target azimuth of different time is obtained, and the relative radial velocity of each time target is calculated using the relative radial velocity calculation formula based on Doppler shift;Step 2, the target azimuth and target relative radial velocity of adjacent two time are selected, and the target real relative motion speed is obtained by velocity vector relationship calculation;Step 3, the motion speed of the ship is compensated by target real relative motion speed, and the target real absolute motion speed is obtained;Step 4, based on target real relative motion speed, the target relative distance of each time is obtained.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of acoustic signal processing target recognition, and particularly relates to a continuous active sonar target ranging method. BACKGROUND

[0002] At present, active sonar devices can be generally divided into two types from the detection system, i.e. pulse sonar and continuous sonar. In comparison with the traditional pulse sonar, the continuous active sonar can continuously and stably track the target, and thus has been widely concerned at home and abroad.

[0003] However, the continuous sonar is free from the emission cycle limitation, but under the condition of narrowband detection, the target distance estimation becomes difficult. Referring to the target motion analysis method for passive target ranging, the distance of the target detected by the narrowband continuous active sonar can be estimated, but still has the lag characteristic of the target motion analysis, and the precision is limited. The present application aims at the problem of difficult ranging of the narrowband continuous active sonar, and proposes a continuous active sonar target positioning method based on motion trend estimation, so as to solve the problem. SUMMARY

[0004] The present application aims to provide a continuous active sonar target ranging method to solve the problem of difficult ranging of the narrowband continuous active sonar.

[0005] To achieve the above object, the present application provides the technical scheme as follows.

[0006] A continuous active sonar target ranging method, the method comprising the following steps:

[0007] Step 1, obtaining the target azimuth angle at different time, and calculating the target relative radial velocity at each time by using the relative radial velocity calculation formula based on Doppler shift;

[0008] Step 2, selecting the target azimuth angle and the target relative radial velocity at adjacent two times, and obtaining the target real relative motion velocity by calculating the velocity vector relationship;

[0009] Step 3, compensating the motion velocity of the ship by using the target real relative motion velocity to obtain the target real absolute motion velocity;

[0010] Step 4, obtaining the target relative distance at each time based on the target real relative motion velocity.

[0011] Preferably, the relative radial velocity calculation formula based on Doppler shift is s=c*(f'-f) / 2, s is the target relative radial velocity, c is the speed of light, f' is the frequency of the emitted signal, and f is the frequency of the target echo.

[0012] Preferably, the step 2 comprises the following steps:

[0013] Step 2.1, constructing a target relative motion speed solving equation set Wherein, s1, s2 are target relative radial velocities at t1, t2, β1, β2 are target azimuth angles at t1, t2, are components of the target real relative motion speed in x-axis and y-axis.

[0014] Step 2.2, selecting the target azimuth angle and the target relative radial velocity at adjacent two time points, and calculating the components of the target real relative motion speed in x-axis and y-axis;

[0015] Step 2.3, obtaining the target real relative motion speed through a first speed vector relationship, and the first speed vector relationship calculation formula is S op is the size of the target real relative motion speed, β op is the target heading.

[0016] Preferably, the step 3 comprises the following steps:

[0017] Adding the components of the target real relative motion speed in x-axis and y-axis to the components of the ship motion speed V1 in x-axis and y-axis respectively to obtain the components of the target real absolute motion speed in x-axis and y-axis, and calculating the size and heading of the target real absolute motion speed through a second speed vector relationship;

[0018] The second speed vector relationship calculation formula is

[0019]

[0020] S ab is the size of the target real motion speed, β ab is the target heading, is the component of the target real absolute motion speed in x-axis and y-axis.

[0021] Preferably, the step 4 comprises the following steps:

[0022] Step 4.1, constructing an initial relative distance solving equation set based on the target real relative motion speed, and the initial relative distance solving equation set is Wherein, (X1, Y1) represents the target relative ship position at t1, D1 represents the distance of the target from the ship at t1, β1, β2 are target azimuth angles at t1, t2, s op , β opD x 、D y is the motion distance of the target along the x-axis and the y-axis within the time t2-t1;

[0023] Step 4.2, the distance D1 of the target from the ship at the time t1 is solved based on the initial relative distance solving equation group;

[0024] Step 4.3, the relative position (X1, Y1) of the target to the ship at the time t1 is determined based on the distance D1 of the target from the ship at the time t1, and the relative position of the target to the ship and the motion distance D x 、D y of the target from the ship at the time t2 is calculated;

[0025]

[0026] Compared with the prior art, the present application has the beneficial effects that:

[0027] The present application uses the target azimuth measured at two or more times and the relative radial velocity of the target solved by the Doppler shift to obtain the real relative motion speed and the azimuth of the target, so as to obtain the relative distance of the target. The method makes up for the defect that the narrowband continuous sonar cannot measure the distance, and through the establishment of the target radial velocity-azimuth equation group, the real-time solving of the absolute speed, the heading, the distance and other motion elements of the target is realized by estimating the target radial velocity and the azimuth at continuous times, the high-precision real-time positioning of the target under the condition of continuous active detection is realized, the positioning accuracy reaches 98.5%, the problems of distance estimation lag and poor estimation accuracy of the conventional target motion analysis method are solved, and strong support is provided for the development and application of the continuous active sonar detection technology. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is the flow chart of the present application.

[0029] Fig. 2 is a schematic diagram of the relative situation of the ship and the target.

[0030] Figure 3 is the vector relationship diagram of the relative speed of the target and the absolute speed of the ship and the absolute speed of the target.

[0031] Figure 4 is the vector relationship diagram of the relative speed of the target and the radial velocity measured at different times.

[0032] Figure 5 is the situation diagram of the simulation experiment.

[0033] Figure 6 is the result diagram of the simulation experiment. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] FIG2 shows the relative situation of the own ship (receiving platform) and the target in this embodiment, and both the own ship and the observed target are moving: the own ship is always moving in a uniform linear motion at a speed V1, and the angle between the own ship's heading and the positive direction of the x-axis is α, and the target is always moving in a uniform linear motion at a speed V2; as shown in FIG2(a), the own ship measures the target at an azimuth angle β1 of the receiving platform at the observation time t1, and the own ship measures the target relative radial velocity s1, where the measured target relative radial velocity s1 is the projection of the target's true relative motion velocity on the β1 azimuth; as shown in FIG2(b), after time T reaches the observation time t2, both have moved to new positions, and the own ship measures the target at an azimuth angle β2 of the receiving platform at the observation time t2, and the own ship measures the target relative radial velocity s2 at the observation time t2; Figure 3 As shown in the figure, the target relative radial velocity s2 measured at the second observation time t2 is the projection of the target's true relative motion velocity V3 on the β2 direction. The target relative radial velocity vector measured at the observation time 1 and the observation time 2 is as follows: Figure 4 As shown in the figure, the arrow in the first quadrant is the direction of the line from the own ship to the target observation point (own ship), and its magnitude is obtained by converting the measured Doppler frequency shift; the arrow in the second quadrant is the target's true relative motion velocity vector.

[0036] Move the target relative radial velocity vector at observation time 1, the target relative radial velocity vector at observation time 2, and the target true relative motion velocity vector to the origin of the rectangular coordinate system. The relationship between the vectors is as follows: Figure 4 As shown in the figure, the target relative radial velocity vector measured at each moment is the projection of the target's true relative motion velocity vector on each target azimuth. Therefore, the target relative motion velocity solution equation group can be established to solve the target's true relative motion velocity vector v op Size S op and direction β op , the target relative motion velocity solution equation group is shown in formula (1):

[0037]

[0038] Among them, s1 and s2 are the target relative radial speeds at time t1 and t2, β1 and β2 are the target azimuths at time t1 and t2, The component of the target real relative motion velocity in the x-axis and y-axis.

[0039] Referring to Figure 1 A continuous active sonar target ranging method is shown in the figure, which includes 4 steps.

[0040] Step 1, obtain the target azimuth angle at different time, and calculate the target relative radial velocity at each time by using the relative radial velocity calculation formula based on Doppler shift, which is shown in formula (2),

[0041] s=c*(f'-f) / 2 (2)

[0042] Wherein, s is the target relative radial velocity, c is the speed of light, f' is the frequency of the transmitted signal, and f is the echo frequency of the target.

[0043] Step 2, select the target azimuth angle and target relative radial velocity of adjacent two time, and calculate the target real relative motion velocity through the velocity vector relationship, taking figure 2 as an example, which includes the following 3 sub steps:

[0044] Step 2.1, construct the target relative motion velocity solving equation set, which is shown in formula (1),

[0045] Step 2.2, select the target azimuth angle β1, β2 and target relative radial velocity s1, s2 of observation time t1 and observation time t2, and calculate the component of target real relative motion velocity in x-axis and y-axis through formula (1)

[0046] Step 2.3, calculate the target real relative motion velocity through the first velocity vector relationship, and the first velocity vector relationship formula is shown in formula (3),

[0047]

[0048] Wherein, S op is the size of target real relative motion velocity, β op is the target heading.

[0049] Step 3, compensate the target real relative motion velocity with the motion velocity of the ship, and obtain the target real absolute motion velocity, which includes the following 2 sub steps:

[0050] Step 3.1, add the component of target real relative motion velocity in x-axis and y-axis with the component of ship motion velocity V1 in x-axis and y-axis respectively, and obtain the component of target real absolute motion velocity in x-axis and y-axis, which is shown in formula (4),

[0051]

[0052] wherein, V1*cosβ1, V1*sinβ1 are the components of the target real relative motion velocity on the x-axis and y-axis, V1*cosβ1, V1*sinβ1 are the components of the target real relative motion velocity on the x-axis and y-axis,

[0053] Step 3.2, calculating the size and heading of the target real absolute motion velocity by a second speed vector relationship, the formula of which is shown in formula (5),

[0054]

[0055] wherein, S ab is the size of the target real motion velocity, β ab is the heading of the target, V1*cosβ1, V1*sinβ1 are the components of the target real relative motion velocity on the x-axis and y-axis.

[0056] Step 4, obtaining the target relative distance at each time based on the target real relative motion velocity, specifically including the following 3 sub-steps:

[0057] Step 4.1, constructing an initial relative distance solving equation set based on the target real relative motion velocity, the formula of which is shown in formula (6),

[0058]

[0059] wherein, (X1, Y1) represents the target relative ship position at t1, that is, the coordinate of the target relative to the ship position at the observation time, D1 represents the distance of the target from the ship at t1, β1 and β2 are the target azimuth angles at t1 and t2 respectively, S op , β op is the size of the target real relative motion velocity and the heading of the target, is the motion distance of the target along the x-axis and y-axis within t2-t1,

[0060] Step 4.2, solving the distance D1 of the target from the ship at t1 based on the initial relative distance solving equation set;

[0061] Step 4.3, calculating the target relative ship position (X1, Y1) at t1 based on the distance D1 of the target from the ship at t1 and combining formula (6), that is, (X1, Y1) = (D1*cosβ1, D1*sinβ1); calculating the target relative ship position (X1, Y1) at t1 based on the target relative ship position (X1, Y1) at t1 and the motion distance D x , Dy , calculate the distance between the target and the ship at time t2

[0062]

[0063] In the present application, the position of the ship (receiving platform) at observation time one is taken as the origin of the rectangular coordinate system, so the coordinates of the ship at observation time two are (V1*T*cosα, V1*T*sinα);

[0064] The coordinates of the target at observation time two are:

[0065] (V1*T*cosα+D2*cosβ2, V1*T*sinα+D2*sinβ2)

[0066] The present application is verified by simulation experiment, and the simulation situation is shown in Figure 5 The receiving platform is assumed to move at a speed of 5 m / s in the direction of azimuth 270 degrees at a constant speed in a straight line, the target moves at a speed of 4 m / s in the direction of azimuth 0 degrees at a constant speed in a straight line, the initial position of the target is (-3000, 4000), the initial distance from the observation point is 5000 meters, the target azimuth and the target relative radial velocity are recorded every 60 seconds, and the target relative radial velocity measurement data are taken as 3 significant figures. Figure 6 The target movement speed, actual movement direction, actual distance from the receiving platform, calculated speed, calculated movement direction and calculated distance are listed. According to the results in the table, the method can effectively calculate the movement parameters and distance of the target, and the distance error obtained by calculation is small under the premise that the target azimuth and the target relative radial velocity are relatively accurate.

Claims

1. A continuous active sonar target ranging method, characterized in that: The method comprises the following steps: Step 1: Obtain the target azimuth at different times and calculate the target relative radial velocity at each time using the relative radial velocity calculation formula based on Doppler shift; Step 2: Select the target azimuth and target relative radial velocity at two adjacent moments, and calculate the target's true relative motion velocity through the velocity vector relationship; The step 2 comprises the following steps: Step 2.1: Construct the target relative motion speed solution equation group ， Among them, s1 and s2 are the target relative radial speeds at time t1 and t2, β1 and β2 are the target azimuths at time t1 and t2, is the component of the target's true relative motion velocity on the x-axis and y-axis; Step 2.2: Select the target azimuth and target relative radial velocity at two adjacent moments, and calculate the components of the target's true relative motion velocity on the x-axis and y-axis. Step 2.3, the target's true relative motion speed is calculated by the first velocity vector relationship. The calculation formula of the first velocity vector relationship is: , S op is the target’s true relative velocity, β op The target heading; Step 3: Compensate the target's true relative speed with the ship's speed to obtain the target's true absolute speed. Step 4: Obtain the target relative distance at each moment based on the target's true relative motion speed.

2. A continuous active sonar target ranging method according to claim 1, characterized in that: The step 3 comprises the following steps: The components of the target's true relative velocity on the x-axis and y-axis are added to the components of the ship's velocity V1 on the x-axis and y-axis respectively to obtain the components of the target's true absolute velocity on the x-axis and y-axis, and the magnitude and heading of the target's true absolute velocity are calculated through the second velocity vector relationship; The second velocity vector relationship calculation formula is: ， S ab is the actual speed of the target, β ab For the target heading, It is the component of the target's true absolute velocity on the x-axis and y-axis.

3. The method for continuous active sonar target ranging according to claim 1, wherein: The step 4 comprises the following steps: Step 4.1: construct an initial relative distance solution equation group based on the target's true relative motion speed. The initial relative distance solution equation group is: ， Among them, (X1, Y1) represents the position of the target relative to the ship at time t1, D1 represents the distance between the target and the ship at time t1, β1 and β2 are the target azimuths at time t1 and t2 respectively, and S op , β op is the target’s true relative motion speed and target heading, D x 、D y is the movement distance of the target along the x-axis and y-axis during the time t2-t1; Step 4.2, calculate the distance D1 between the target and the ship at time t1 based on the initial relative distance solution equations; Step 4.3: Determine the relative position of the target to the ship (X1, Y1) at time t1 based on the distance D1 between the target and the ship at time t1, and the target's relative position to the ship and the target's movement distance D along the x-axis and y-axis during the time t2-t1. x 、D y , calculate the distance between the target and the ship at time t2 .

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