JP5353727B2 - Sound source position estimation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an estimation error of a sound source position, even when an arrival time difference observation value has an error. <P>SOLUTION: Each table value of an arrival time difference is stored separately relative to a multipath wave having an upward arrival angle of elevation/depression and a multipath wave having an downward arrival angle of elevation/depression (209M), and each received multipath wave is determined whether its arrival angle of elevation/depression is upward or downward, and the degree of disagreement between the observed arrival time difference and the table value is calculated separately relative to the multipath wave having the upward angle of elevation/depression and the multipath wave having the downward angle of elevation/depression, and the sum thereof is used as a cost function (210), and the sound source position is estimated (211). <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a sound source position estimation device, and more particularly to a device that receives a direct wave and a multipath wave of a pulsed sound wave radiated from a sound source in water and estimates the position of the sound source from the arrival time difference therebetween.

In underwater sound wave propagation, in addition to the sound waves (direct waves) that arrive directly at the receiver from the sound source, there are multipath waves that arrive after being reflected at the sea surface or the sea floor. Arrives at different times.
As a technique for receiving a pulsed sound wave from a sound source in water and estimating the position of the sound source, there is one disclosed in Patent Document 1 below.

  FIG. 1 shows a conventional sound source position estimation apparatus disclosed in Patent Document 1. In the illustrated sound source position estimation apparatus, a signal representing a sound wave received by an acoustic sensor (receiver) is input to a multipath wave arrival time difference measuring device 102 via an input terminal 101. Multipath wave arrival time difference measuring device 102 detects the arrival time difference between the direct wave and the multipath wave, and outputs data indicating the detected arrival time difference observation value.

  On the other hand, the arrival time difference table generator 103 estimates the arrival time of the sound wave by calculating the sound ray of the sound wave from each virtual sound source based on the underwater sound velocity profile, and the estimated result is the arrival time difference table value (theoretical value). As you remember.

  The cost function calculator 104 is a cost reflecting the degree of inconsistency between the observed multipath wave arrival time difference obtained by the multipath wave arrival time difference measuring unit 102 and the arrival time difference table value obtained by the arrival time difference table creator 103. Calculate the value of the function.

A detailed block configuration of the cost function calculator 104 is shown in FIG.
A multipath wave arrival time difference observation value obtained by the multipath wave arrival time difference measuring device 102 is input to the input terminal 111, and a table value from the arrival time difference table creator 103 is input to the input terminal 112. The table value-observation value calculator 113 calculates the difference between the arrival time difference observation value and the arrival time difference table value.

Here, p is an index corresponding to the distance from the receiving position (receiving point) to the sound source position, and q is an index corresponding to the depth of the sound source position, and the nth obtained by the multipath wave arrival time difference measuring device 102. The arrival time difference for the incoming wave is D _n , and the n-th arrival time difference table value from the virtual sound source at the virtual sound source position (p, q) obtained by the arrival time difference table creator 103 is E _n (p, q). In this case, the table value-observed value difference calculator 203 calculates the difference between the table value and the observed value by the following equation (1).
ΔD _n (p, q) = E _n (p, q) −D _n (1)

  The sum-of-squares calculator 114 obtains the sum of all multipath waves (represented by the following formula (2)) as a cost function, although the square of the calculation result of the formula (1), and the obtained cost function Is output from the output terminal 115.

  The sound source position estimator 105 in FIG. 1 obtains (p, q) that minimizes the cost function given by equation (2), and the obtained (p, q) represents the sound source position of the estimation target (target). And the estimation result is output via the output terminal 106.

JP 2006-194627 A

  However, when the above-mentioned conventional apparatus is used, the value of the cost function on the line connecting the sound source and the receiver becomes a small value over a considerably wide range before and after the position of the sound source, so that the sound source position is accurately estimated. There was a problem that I could not. That is, since the arrival time difference obtained by the multipath wave arrival time difference measuring device 102 includes an observation error, there is a high possibility that the estimated value is greatly shifted at a place where the value of the cost function is small, and thus the observation error is relatively large. was there.

As an example, consider the case where the sound speed is constant and the water depth Zb is constant as shown in FIG. In FIG. 3, Zs is the depth of the sound source, Zr is the depth of the receiving point, and r is the horizontal distance from the receiving point WR to the sound source WS.
FIG. 4 shows the result of calculating the cost function when there is no error in the arrival time difference observation values. The horizontal axis represents the distance r in the horizontal direction from the receiving point Zr, and the vertical axis represents the depth (depth is greater in the downward direction) z. The curve in the figure is a contour of the cost function, and the position where this cost function is minimum is estimated.

  If there is no error in the arrival time difference observation value, the true value can be estimated. However, the cost function in the figure shows the cost along the direction of the line connecting the receiver and the sound source (direction of arrow DMC). Since the change in the function is small, if the observed value of the arrival time difference includes an error, the estimation result may deviate from the true sound source position along this direction. When empirically known observation errors were given and the simulation was tried 30 times under the conditions shown in FIG. 3, the standard error of the distance error was about 15% of the true distance value, which was a fairly large value. . Thus, there is a problem that the position estimation error of the sound source is large due to the characteristics of the cost function.

The sound source estimation apparatus of the present invention is
In a sound source estimation device that estimates the position of a sound source based on an incoming wave at a receiving position,
For each of the plurality of virtual sound source positions, when the virtual sound source is assumed to exist at the virtual sound source position, the arrival angle of the first incoming wave and the second and subsequent incoming waves at the receiving position is upward. The arrival time difference theory for storing the theoretical value of the arrival time difference between each of them, and the theoretical value of the arrival time difference between each of the first arrival wave and the second and subsequent arrival waves at the receiving position where the arrival angle is downward. Value storage means;
An arrival time difference observation value calculation means for calculating an observation value of an arrival time difference between the first arrival wave from the target sound source and the second and subsequent arrival waves, based on the arrival wave data observed at the receiving position;
It is determined whether the arrival elevation angle of each of the second and subsequent arrival waves is upward or downward, and among each of the second and subsequent arrival waves, each of the arrival waves having an upward elevation angle, and the first arrival wave, And the theoretical value of the arrival time difference for an incoming wave with an upward angle of elevation rising as the first inconsistency, and the incoming elevation angle of the second and subsequent incoming waves is downward A degree of inconsistency between the arrival time difference between each of the first arrival waves and the first arrival wave and the theoretical value of the arrival time difference for the arrival wave having the downward angle of elevation is defined as a second inconsistency; A cost function calculating means for obtaining a sum of the first mismatch degree and the second mismatch degree as a cost;
Sound source position estimating means for estimating the virtual sound source position at which the cost calculated by the cost function calculating means is the minimum as the position of the target sound source.

  According to the present invention, it is possible to reduce the estimation error of the sound source position even when there is an error in the arrival time difference observation value.

It is a block diagram which shows the conventional sound source position estimation apparatus. It is a block diagram which shows the detail of the cost function calculator 104 of FIG. It is a figure which shows the propagation path of a sound wave in case sound velocity is constant and water depth is constant. It is a figure which shows an example of the contour line of the cost function calculated | required with the apparatus of FIG. It is a block diagram which shows the sound source position estimation apparatus by Embodiment 1 of this invention. FIG. 3 is a diagram showing an arrangement of receivers in the first embodiment. It is a graph which shows an example of the envelope of the absolute value of the sample value in a receiver. (A) And (b) is a figure which shows an example of the timing of reception in a pair of receiver. It is a figure which shows an example of the virtual sound source position used on creation of an arrival time difference table. It is a figure which shows an example of the propagation path from the sound source of virtual sound source position WS. FIG. 6 is a functional block diagram illustrating an example of an arrival time difference table creation unit 209 in FIG. 5. FIG. 6 is a functional block diagram illustrating an example of a cost function calculator 210 in FIG. 5. It is a figure which shows an example of the contour line of the cost function calculated | required with the apparatus of FIG. It is a block diagram which shows the sound source position estimation apparatus by Embodiment 2 of this invention. It is a functional block diagram which shows an example of the cost function calculator 220 of FIG. It is a functional block diagram which shows an example of the elevation angle determination part 825 of FIG. (A) And (b) is a figure which shows an example of the timing of reception in a pair of receiver.

Embodiment 1 FIG.
FIG. 5 shows a sound source position estimation apparatus according to the first embodiment of the present invention.
The illustrated sound source position estimation device receives a direct wave and a multipath wave of a pulsed sound wave radiated from a sound source, and estimates the position of the sound source based on the arrival time difference between them. And the horizontal distance from the receiver. Note that information indicating the direction in which the sound source is located is obtained separately.

The sound source position estimation apparatus according to Embodiment 1 includes first and second receivers 201 and 202.
As will be described later, the first receiver 201 and the second receiver 202 are provided to obtain information on whether the elevation angle of the incoming wave is upward or downward, and are different on the same vertical line. In the position. With this arrangement, the elevation angle of the incoming wave is upward based on whether the incoming wave (signal) has arrived at the first receiver 201 or the second receiver 202 earlier. Or down.

Since the first and second receivers 201 and 202 only need to be able to determine whether the elevation angle is upward or downward, they are arranged with a gap DWR as shown in FIG. The interval DWR is set to a value equal to or greater than the product of the maximum sound speed assumed at the reception position and the minimum time difference measurable by the receivers 201 and 202.
Since the first and second receivers 201 and 202 are disposed on the upper side and the lower side, respectively, they may be referred to as “upper receiver” and “lower receiver”.

The outputs of the upper and lower receivers 201 and 202 are input to first and second arrival time determination units 205 and 206 via input terminals 203 and 204, respectively.
The first and second arrival time determination units 205 and 206 determine or detect arrival times based on the outputs of the upper and lower receivers 201 and 201, respectively.

  The first and second receivers 201 and 202 output data representing sample values obtained by sampling the sound waves received by them, but the absolute values of the sample values obtained by sampling the sound waves The envelopes of those arranged on the time axis are, for example, as shown in FIG. Note that an envelope of the square value of the sample value may be used instead of the absolute value of the sample value.

  The first and second arrival time determination units 205 and 206 determine the arrival time (arrival time) of the incoming wave based on the data strings from the upper and lower receivers 201 and 202, respectively. For the determination of the arrival time, a method based on replica correlation, a method based on rising edge detection, or the like can be used as in the past. These methods are described, for example, as part of the operation of the multipath wave arrival time difference measuring device in Patent Document 1.

FIGS. 8A and 8B show the arrival of pulse waves in the upper receiver 201 and the lower receiver 202 determined or detected by the first and second arrival time determination units 205 and 206. Indicates the time (detection timing). 8A shows the detection timing in the upper receiver 201 in the order of TA ₁ , TA ₂ ,..., And FIG. 8B shows the detection timing in the lower receiver 202 earlier. in turn _TB 1, _{TB 2,} shown in ....
If noise is erroneously detected as a signal or no detection omission occurs, the first detection timing is a direct wave detection timing, and the second and subsequent detection timings are multipath wave detection timings.

The first multipath wave arrival time difference calculation unit 207, based on the output of the first arrival time determination unit 205, receives the arrival time difference (first arrival) for each of the multipath waves received by the upper receiver 201. The difference in arrival time from the wave) is calculated. That is, the arrival time difference DU ₂ between the _first arrival wave PA ₁ and the second arrival wave PA ₂ (first multipath wave), the arrival time difference DU between the first arrival wave PA ₁ and the third arrival wave PA _{3. 3. In} general, the arrival time difference DU _n between the _first arrival wave PA ₁ and the nth arrival wave PA _n (n = 2, 3,...) Is calculated. The data sequence [DU ₂ , DU ₃ ,...] Indicating the arrival time difference DU _n calculated in this way is supplied to the cost function calculator 210.

Similarly, the second multipath wave arrival time difference calculation unit 208, based on the output of the second arrival time determination unit 206, receives the arrival time difference for each of the multipath waves received by the lower receiver 202 ( The arrival time difference from the first arrival wave is calculated. That is, the arrival time difference DL ₂ between the _first arrival wave PB ₁ and the second arrival wave PB ₂ (first multipath wave), the arrival time difference DL between the first arrival wave PB ₁ and the third arrival wave PB _{3. 3. In} general, the arrival time difference DL _n between the _first arrival wave PB ₁ and the nth arrival wave PB _n (n = 2, 3,...) Is calculated. The data string [DL ₂ , DL ₃ ,...] Indicating the arrival time difference DL _n calculated in this way is supplied to the cost function calculator 210.

  The combination of the first arrival time determination unit 205 and the first multipath wave arrival time difference calculation unit 207 has the same function as the multipath wave arrival time difference measurement unit 102 in FIG. The combination of 206 and the second multipath wave arrival time difference calculation unit 208 also has the same function as that of the multipath wave arrival time difference measuring device 102 of FIG.

  As described above, the first multipath wave arrival time difference calculation unit 207 and the second multipath wave arrival time difference calculation unit 208 are based on the arrival time (detection timing) of the arrival wave observed at the receiving position. An arrival time difference observation value calculation means for calculating an observation value of an arrival time difference between the first arrival wave from the estimation target (target) sound source and each of the second and subsequent arrival waves is configured, and the first multipath wave is included. An arrival time difference calculation unit 207 calculates an observation value of an arrival time difference between the first arrival wave to the first receiver 201 and each of the second and subsequent arrival waves, and a second multipath wave arrival time difference calculation unit 208 calculates an observed value of the arrival time difference between the first incoming wave to the second receiver 202 and each of the second and subsequent incoming waves.

  The arrival time difference table creator 209 creates an arrival time difference table based on the virtual sound source setting position data supplied via the input terminal 213 and the sound velocity profile data supplied via the input terminal 214, and the storage unit 209M. Save to.

For example, the virtual sound source position when the arrival time difference table is created is set as shown in FIG.
In the example shown in FIG. 9, the search area is virtually divided into a mesh (lattice) shape, and each intersection is defined as a virtual sound source position (p, q) (p = 1, 2,... P, q = 1, 2,. ). Note that p and q are not the values representing the distance r and the depth z, but are indices corresponding to the distance and the depth, and are represented by natural numbers 1 to P and 1 to Q.

  The mesh width (interval of virtual sound source positions) is set according to the estimation accuracy of a desired sound source position. As the mesh width is narrowed, measurement can be performed with higher accuracy. However, the amount of data and calculation increases, and real-time processing becomes difficult. Therefore, the mesh width is narrowed when high accuracy is required, and the mesh width is widened when high speed is important.

A propagation path from the virtual sound source position WS is assumed as shown in FIG. 10, for example. FIG. 10 shows only five propagation paths WP1 to WP5 for simplicity. The reason why the propagation path (sound ray: flow of sound energy) is not linear is that the speed of sound is not constant due to non-uniformity such as water temperature and salinity.
A wave that reaches the receiving point WR without being reflected once is called a direct wave, and a wave that has reflected at the sea surface or the bottom of the sea once and reached the receiver is called a multipath wave.

Based on such an assumption, the arrival time difference from each of the virtual sound source positions is estimated, and an estimated value (theoretical value) is obtained as a time difference table value and stored in the storage unit 209M. When it is assumed that a pulsed sound wave is emitted at each of the virtual sound source positions, the arrival time difference table generator 209 determines the estimated arrival time of the first arrival wave (direct wave) in the upper receiver 201 and the upper Estimated value or theoretical value EU _i (i = _i ) of the difference (arrival time difference) from the arrival time of the multipath wave estimated to arrive at the receiver 201 at the i-th (i = 1, 2,...) Upward elevation angle. 1,2, set to column _{[EU 1, EU 2, ...} EU I] of ...), and determined for all the virtual sound source, and stores in the storage unit 209M, similarly, first in the lower side of the receivers 202 And the arrival time of the multipath wave estimated to arrive at the j-th (j = 1, 2,...) At a downward elevation angle at the lower receiver 202. the difference between the estimated value to the theoretical value _EL j of (arrival time difference) (j = 1,2, ...) To column _{[EL 1, EL 2, ...} EL J] a, calculated for all the virtual sound source, and stores in the storage unit 209M. In this way, the storage unit 209M plays a role as arrival time difference theoretical value storage means.

  Note that I is empirically estimated to be receivable by the receiver 201 and is a value equal to or greater than the maximum number of multipath waves whose elevation angle is upward, and J is empirically receivable by the receiver 202. The estimated angle of elevation is set to a value equal to or greater than the maximum number of multipath waves with downwards.

A sequence EU ₁ (p of arrival time differences at the upper receiver 201 for each of all the virtual sound source positions (p, q) (p = 1, 2,... P, q = 1, 2,... Q). , Q), EU ₂ (p, q),... (P = 1, 2,... P, q = 1, 2,... Q)
Are obtained as table format data, and are stored in the storage unit 209M of the arrival time difference table creator 209 as the upward elevation angle arrival time difference table value.
Similarly, a sequence of arrival time differences EL ₁ (p, q), EL ₂ (p, q),... (P) at the lower receiver 202 for each of the virtual sound source positions (p, q). = 1, 2, ... P, q = 1, 2, ... Q)
Are obtained as data in a table format, and stored in the storage unit 209M of the arrival time difference table creator 209 as a downward elevation angle arrival time difference table value.

  The cost function calculator 210 receives the outputs (signals indicating arrival times) of the first and second arrival time determination units 205 and 206 as input, and the first and second multipath wave arrival time difference calculation units 207 and The arrival time difference data (observation value) obtained in 208 and the arrival time difference table value (theoretical value) created by the arrival time difference table creator 210 are input, a cost function is obtained based on these values, and the obtained cost function Is input to the sound source position estimator 211.

  The sound source position estimator 211 uses the distance and depth of the virtual sound source that minimizes the cost function created by the inter-cost calculator 210 as an estimated value of the sound source position, and outputs the estimated value from the output terminal 212.

Hereinafter, the operation of the arrival time difference table creator 209 will be described in more detail with reference to FIG.
From the input terminal 213, setting values of an index P representing the distance r of the virtual sound source and an index Q representing the depth z are input.
A sound speed profile is input from the input terminal 214.
The sound ray calculation processing unit 703 performs sound ray calculation based on these data. As a result of the sound ray calculation, an estimated value (theoretical value) of the arrival time of each incoming wave and an estimated value (theoretical value) of the arrival elevation angle are obtained.

  The elevation angle determination unit 704 determines whether the arrival elevation angle is upward or downward for each multipath wave from each virtual sound source position based on the calculation result in the sound ray calculation processing unit 703, and the determination result is received. This is supplied to the time difference calculation unit 705.

  The arrival time difference calculation unit 705 is based on the calculation result in the sound ray calculation processing unit 703, and further, on the multipath wave determined to be upward based on the determination result in the elevation angle determination unit 704, in the upper receiver 201. An arrival time difference (difference between arrival times of the direct wave and the multipath wave) is calculated, and the calculated arrival time difference (estimated value) is written as a table value in the up-and-down arrival time difference table 706 in the storage unit 209M. For the determined multipath wave, the arrival time difference (difference between the arrival time of the direct wave and the multipath wave) in the lower receiver 202 is calculated, and the calculated arrival time difference (estimated value) is stored in the storage unit 209M. Is written as a table value in the up-down arrival time difference table 707.

As a result of performing such processing, the multipath arriving from the respective virtual sound source positions (p, q) and arriving at the upper receiver 201 from the upper side (at the upward elevation angle) in the uplift arrival time difference table 706. A set of data representing the arrival time difference for each of the waves is stored for each virtual sound source, and the rising and falling arrival time difference table 707 emits from each virtual sound source position (p, q) and receives the lower wave. A data set representing the arrival time difference for each of the multipath waves arriving from the lower side (at a downward elevation angle) to the device 202 is stored for each virtual sound source.
The data stored in these tables 706 and 707 are supplied to the cost function calculator 210 via terminals 708 and 709 as described later.

Next, the operation of the cost function calculator 210 will be described in more detail with reference to FIG.
The input terminal 801 is supplied with the output of the first arrival time determination unit 205, the input terminal 802 is supplied with the output of the second arrival time determination unit 206, and the input terminal 803 is supplied with the first multi-timer. The output of the path wave arrival time difference calculation unit 207 is supplied, and the output of the second multipath wave arrival time difference calculation unit 208 is supplied to the input terminal 804.

  The elevation angle determination unit 805 receives the outputs of the first and second arrival time determination units 205 and 206 via the input terminals 801 and 802, and the elevation angle for each of the incoming waves received by the receivers 201 and 202. Is upward or downward, and a determination result YUL is output.

  In the example shown in FIGS. 8A and 8B, the first receiver 201 receives the first, second, and fourth incoming waves at an earlier timing, and the third, fifth, For the incoming wave, the lower receiver receives it at an earlier timing. From these facts, the first, second, and fourth incoming waves arrive from above, that is, the elevation angle is upward, and the third and fifth incoming waves arrive from below. It can be seen that the elevation angle is downward.

  Based on the determination result YUL in the elevation angle determination unit 805, the data extraction unit 806 uses the elevation angle determination unit 805 to increase the elevation angle among the data representing the arrival time difference output from the first multipath wave arrival time difference calculation unit 207. Only the arrival time difference for the multipath wave determined to be upward is selected or extracted and supplied to the up-and-down table value-one observation value difference calculator 808.

  Based on the determination result YUL in the elevation angle determination unit 805, the data extraction unit 807 uses the elevation angle determination unit 805 to increase the elevation angle among the data representing the arrival time difference output from the second multipath wave arrival time difference calculation unit 208. Only the arrival time difference for the multipath wave determined to be downward is selected or extracted and supplied to the up-down table value-one observation value difference calculator 809.

The arrival time difference at the upper receiver 201 for the multipath wave determined to be upward by the elevation angle determination unit 805 is represented by FU _a (a = 1, 2,...)
The arrival time difference at the lower receiver 202 for the multipath wave determined to be downward by the elevation angle determination unit 805 is represented by FL _b (b = 1, 2,...).
If each multipath propagation path is as shown in FIG. 10 (that is, as estimated), the first, second and fourth incoming waves (direct wave and first and third multipath waves) are upward. And the third and fifth incoming waves (second and fourth multipath waves) will have a downward elevation angle, and therefore
FU ₁ = DU ₂ ,
FU ₂ = DU ₄ ,
FL ₁ = DL ₃ ,
FL ₂ = DL ₅
It becomes.
The arrival time differences FU ₁ , FU ₂ ,... Are supplied to the up / down table value one observed value difference calculator 808, and the arrival time differences FL ₁ , FL ₂ ,. Is done.

  Note that since the difference in reception timing at the receivers 201 and 202 for the same incoming wave is extremely small, for example, if the difference in detection timing is equal to or less than a predetermined value, it may be determined that the same incoming wave has been received. . In addition, a sequence of sample values extending from and before and after the time point determined as the arrival time by the first arrival time determination unit 205, and a sample value extending from and before and after the time point determined as the arrival time by the second arrival time determination unit 206 When the correlation of the columns of the two is high, it may be determined that these arrival times are the same arrival wave detection timing.

The up-and-down table value-one observation value difference calculator 808 is extracted by the data extraction unit 806 out of the observation values of the arrival time difference supplied from the first multipath wave arrival time difference calculation unit 207 via the input terminal 803. The elements FU ₁ , FU ₂ ,... Of the observation value sequence of arrival time differences for the multipath wave facing upward and the upward arrival coming from the upward arrival time difference table 706 via the input terminal 708. Each of the time difference table values EU ₁ (p, q), EU (p, q) ₂ ,... (P = 1 to P, q = 1 to Q) is received, and the difference between the corresponding elements of both Is calculated. That is, if the i-th element of the rising-up arrival time difference table value is EU _i (p, q), and the i-th element of the observed arrival-time difference value for the rising-up multipath wave is FU _i , The calculation represented by the formula is performed.
ΔFU _i (p, q) = EU _i (p, q) −FU _i (3)

The elevation-up-square sum calculator 812 calculates the sum (expressed by the following equation (4)) for all the multipath waves with the elevation angle upward, although the calculation result of the equation (3) is squared.

  In Equation (4), I ′ is I ′ ≦ I, and when a multipath wave with an upward elevation angle is detected up to the I-th, I ′ = I and not detected until the I-th. In this case, the detected elevation angle represents the number of multipath waves having an upward direction.

Similarly, the up-down table value-one observed value difference calculator 809 includes a data extraction unit 807 among the observed arrival time difference values supplied from the second multipath wave arrival time difference calculation unit 208 via the input terminal 802. The elements FL ₁ , FL ₂ ,... Of the observation time difference column for the up-down multipath wave extracted in step S, and the input from the up-down arrival time difference table 707 via the input terminal 709. The elements corresponding to the respective elements of the descending arrival time difference table values EL ₁ (p, q), EL ₂ (p, q),... (P = 1 to P, q = 1 to Q). Calculate the difference between them. That is, if the i-th element of the up-down arrival time difference table value is EL _i (p, q) and the i-th element of the observation time difference of the up-down multipath wave is FL _i , The calculation represented by the formula is performed.
ΔFL _j (p, q) = EL _j (p, q) −FL _j (5)

The up-and-down square sum calculator 813 obtains the sum (represented by the following equation (6)) for all the multi-path waves with the elevation angle downward, although the calculation result of the equation (5) is squared.

  In Equation (6), J ′ is J ′ ≦ J, and when a multipath wave with a downward elevation angle is detected up to the Jth, J ′ = J and not detected until the Jth. In this case, the detected elevation angle represents the number of multipath waves having a downward direction.

The sum calculator 814 performs the following calculation using the calculation results of the equations (4) and (6), and outputs the calculation result from the connection terminal 815.
J (p, q) = JU (p, q) + JL (p, q) (7)
J (p, q) in Expression (7) is a cost function used in the first embodiment.

  The sound source position estimator 211 obtains (p, q) that minimizes the cost function given by Equation (7), and the obtained (p, q) represents the sound source position WS of the estimation target (target). Estimated.

  Both the sums of squares obtained by the equations (4) and (6) become smaller as the degree of coincidence between the observed value and the theoretical value (table value) increases. Therefore, the smaller the value of the cost function in the equation (7) given by the sum of the square sums of the equations (4) and (6), the larger the degree of coincidence (the degree of inconsistency) is small. Therefore, obtaining (p, q) that minimizes the cost function of Equation (7) means obtaining (p, q) having the highest degree of coincidence (the smallest degree of inconsistency).

  By obtaining the cost function as described above and obtaining (p, q) that minimizes the cost function, the sound source position can be accurately estimated. That is, the cost function of the conventional example has a small difference in the cost function in the region along the direction indicated by the arrow DMC in FIG. 4, and therefore, when the arrival time difference observation value has an error, the estimation error of the sound source position is large. However, in the first embodiment, as described above, a separate arrival time difference table is used for each of the upward and downward arrival angles of a multipath wave, and a value indicating a different degree of mismatch ( ) JU and JL are obtained, and the sum of these is used as a cost function to estimate the sound source position, thereby reducing the estimation error.

  As an example, let us consider a case where the sound speed is constant and there is no change in water depth, as in the conventional example. FIG. 13 shows a cost function when there is no error in the arrival time difference observation value under the same conditions as in the conventional example. As in the conventional example, the horizontal axis represents the horizontal distance r from the receiving point Zr, and the vertical axis represents the depth (depth is greater in the downward direction) z. The lines in the figure are the cost function contours. As shown in the figure, the contour line of the cost function becomes an ellipse centered on the true value of the sound source position, and the location close to the receiver changes so as to increase the cost. Therefore, it can be seen that the shape of the cost function is qualitatively improved.

  Similarly to the conventional example, when an empirically known observation error is given and simulation is performed 30 times under the conditions shown in FIG. 3, the standard error of the distance is about 5% of the true distance value. Compared to the conventional example, it was about 1/3, and it was confirmed that it contributed to the reduction in the position estimation error of the sound source.

  In the first embodiment, the difference in arrival time between the two receivers is used to determine the elevation angle. However, instead of the two receivers, for example, a vertical receiver array is used. It is also possible to use it.

Embodiment 2. FIG.
In the method of the first embodiment, there is no problem when the sound wave received by each receiver is composed of only a signal, but noise is erroneously detected as a signal (false detection), or a signal to be detected. If is not detected, there is a problem. In the case of false detection, there is a possibility that the difference in arrival time between receivers is calculated with an incorrect combination, and cost calculation may be performed based on the result of incorrect vertical elevation angle determination, resulting in an error in cost calculation. There is a possibility of incorrect sound source position estimation. When a signal to be detected is not detected, a pair of signals (reception timings) to be used for determining the elevation angle are not prepared, so that comparison with the arrival time difference table (calculation of the mismatch degree) can be performed appropriately. There is no problem.

  FIG. 14 shows a sound source position estimation apparatus according to Embodiment 2 of the present invention. The sound source position estimation apparatus in FIG. 14 is generally the same as the sound source position estimation apparatus shown in FIG. 5, but a cost function calculator 220 is provided instead of the cost function calculator 210 in FIG.

  The cost function calculator 220 in FIG. 14 is configured as shown in FIG. 15, for example. The cost function calculator 220 shown in FIGS. 14 and 15 is generally the same as the cost function calculator 210 shown in FIGS. 5 and 12, except that the receiver position data (via the input terminal 215) ( Represents the inter-receiver distance DWR) and the sound velocity profile data supplied via the input terminal 214. Further, as shown in FIG. 15, an elevation angle determination unit 825 is provided instead of the elevation angle determination unit 805. The elevation angle determination unit 825 has the same function as the elevation angle determination unit 805 and also has the following additional functions.

  FIG. 16 shows details of the elevation angle determination unit 825. The elevation angle determination unit 825 shown in the figure includes an arrival time difference minimum combination calculation unit 853, an inter-receiver maximum arrival time difference calculation unit 855, an observed value / maximum value time difference comparison unit 854, a data extraction unit 858, and an elevation angle up / down And a determination unit 859.

In the arrival time difference minimum combination calculation 853, the arrival of arrival waves in the two receivers 201 and 202 based on the outputs of the first and second arrival time determination units 205 and 206 supplied via the input terminals 801 and 802. Of the times (timing), the combination having the smallest difference is obtained. The operation will be described with reference to FIGS. 17 (a) and 17 (b). The arrival time (timing) in the upper receiver 201 detected by the first arrival time determination unit 205 is tA _c (c = 1, 2,...), And is detected by the second arrival time determination unit 206. The arrival time (timing) in the lower receiver 202 is set to tB _d (d = 1, 2,...), And the combination that minimizes the difference among the arrival times in the two receivers is obtained.

For example, determine the most those in small for each of the time tA _c among the time tB _d, among the time _{tB d (d = 1,2, ...} ), time _{tA c (c = 1,2, ...} ) Those in which the difference is not judged to be the smallest in any of these are excluded.
In the illustrated example, the time tB ₃ is excluded because the difference is not the minimum for any of the times tA _{1 to} tA ₆ .

On the other hand, none of the time tA ₄ and time tA _5, although the difference between the time tB ₅ is minimum, since the direction of the time tA ₄ than the time tA ₅ is small difference between the time tB _5, the time tA ₄ is Left (selected to pair with time tB ₅ ), time tA ₅ is excluded.

As a result, time tA ₁ and time tB ₁ , time tA ₂ and time tB ₂ , time tA ₃ and time tB ₄ , time tA ₄ and time tB ₅ , time tA ₆ and time tB ₆ are paired with each other. Therefore, time tA ₅ and time tA ₃ are considered to be due to noise and are excluded.

In the inter-receiver maximum arrival time difference calculation unit 855, the inter-receiver distance DWR input from the input terminal 215 and the sound velocity value C in the vicinity of the receivers 201 and 202 of the sound velocity profile input from the input terminal 214 are calculated. ,
tmax = DWR / C (8)
Thus, the theoretical maximum value tmax of the time difference between the arrival timing at the receiver 201 and the arrival timing at the receiver 202 of the sound wave that has followed the same propagation path is calculated. Since the receivers 201 and 202 are aligned in the vertical direction, the time difference becomes larger as the absolute value of the angle of elevation of arrival is larger.

The observed value / maximum value time difference comparing unit 854 determines whether or not the time difference (observed value) tobs of the pair of arrival timings (time) determined by the combination calculating unit 853 exceeds the inter-receiver maximum arrival time difference tmax. ,
tobs> tmax
Is determined, and the determination result YVN is output. The determination result YVN is supplied not only to the data extraction unit 858 but also to the data extraction units 806 and 807 of FIG. The determination result YVN indicates whether or not the pair of arrival times in the first and second receivers 201 and 202 has a high probability of being the same arrival wave detection timing (high reliability), and tobs ≦ tmax If so, it means that the probability is high. Therefore, it means that the data of the arrival time is suitable for use in the determination of the elevation angle, the comparison of the arrival time difference, etc. On the contrary, when tobs> tmax If it exists, it means that the probability is low and the data of the arrival time is not suitable for use in the determination of the elevation angle, the comparison of the arrival time difference, and the like.

The data extraction unit 858 outputs the outputs of the first and second arrival time determination units 205 and 206 supplied via the input terminals 801 and 802 based on the determination result YVN by the observed value / maximum value time difference comparison unit 854. , Whether or not to be used for the determination of the elevation angle, data representing the time determined to be used for the determination of the elevation angle (outputs of the arrival time determination units 205 and 206) are extracted, and the elevation angle up / down determination unit 859 is extracted. To supply. That is, for each time pair (detected time determined to be paired with each other),
tobs> tmax
In this case, the time pair is not used for the determination of the elevation angle, and is not supplied to the elevation angle up / down determination unit 859.

On the other hand, for each time pair,
tobs ≦ tmax
In this case, data representing the time pair is extracted and supplied to the elevation angle up / down determination unit 859.

  The elevation angle up / down determination unit 859 determines whether the elevation angle is upward or downward with respect to the data representing the time pair supplied from the data extraction unit 858, and outputs the determination result YUL via the connection terminal 861.

The data extraction unit 806 determines whether the elevation angle determination unit 825 has the determination result (the determination result YUL whether the elevation angle is upward or downward, and the determination result YVN regarding the reliability of the detection timings tA _c and tB _d ). 1 of the multipath wave arrival time difference calculation unit 207 (supplied via the input terminal 803) corresponds to the arrival time extracted by the data extraction unit 858, and the elevation angle up / down determination unit 859 Only arrival time difference data values for which the elevation angle is determined to be upward are extracted and supplied to the elevation-upward table value-one observation value difference calculator 808.

The data extraction unit 807 determines whether the elevation angle determination unit 805 determines whether the elevation angle is upward or downward, and the determination result YVN regarding the reliability of the detection timings tA _c and tB _d . 2 of the multipath wave arrival time difference calculation unit 208 (supplied via the input terminal 804) corresponds to the arrival time extracted by the data extraction unit 858, and the elevation angle up / down determination unit 859 Only the arrival time difference data values for which the elevation angle is determined to be downward are extracted and supplied to the elevation table value-observation value difference calculator 809.

  The up-and-down table value-one observed value difference calculator 808 and the up-and-down table value-one observed value difference calculator 809 in FIG. 15 use the observation values of the arrival time differences extracted by the data extraction units 806 and 807 to calculate a difference. And a cost function based on it. The operation of other parts of the cost function calculator 220 is the same as that described in the first embodiment.

  In the first embodiment, the cost function that discriminates the elevation angle of the incoming sound wave can be used only in an almost ideal situation without the influence of noise, but as described in the second embodiment, the incoming sound wave (Elevation angle determination using only highly reliable data, comparison of arrival time differences (detection of mismatch)), the SN ratio is not so high, Even when there is no detection, it is possible to apply a cost function that discriminates ups and downs of incoming sound waves.

  For this reason, even when the SN ratio is not so high and the arrival time difference is erroneously detected or not detected, the cost function can be kept conical, and the sound source position estimation accuracy can be maintained.

  In the second embodiment, the time difference between the two receivers is used to measure the elevation angle. However, it is possible to determine whether the elevation angle is up or down using three or more receivers.

When the sound speed profile could not be measured, a typical sound speed of 1500 m / s was used instead of the sound speed value C in the vicinity of the receivers 201 and 202 of the sound speed profile of Equation (8).
tmax = DWR / 1500 (9)
It is also possible to use.

  201, 202 receivers, 205, 206 arrival time determination unit, 207, 208 multipath wave arrival time difference calculation unit, 209 arrival time difference table creation unit, 210 cost function calculator, 211 sound source position estimator.

Claims (9)

In a sound source estimation device that estimates the position of a sound source based on an incoming wave at a receiving position,
For each of the plurality of virtual sound source positions, when the virtual sound source is assumed to exist at the virtual sound source position, the arrival angle of the first incoming wave and the second and subsequent incoming waves at the receiving position is upward. The arrival time difference theory for storing the theoretical value of the arrival time difference between each of them, and the theoretical value of the arrival time difference between each of the first arrival wave and the second and subsequent arrival waves at the receiving position where the arrival angle is downward. Value storage means;
An arrival time difference observation value calculation means for calculating an observation value of an arrival time difference between the first arrival wave from the target sound source and the second and subsequent arrival waves, based on the arrival wave data observed at the receiving position;
It is determined whether the arrival elevation angle of each of the second and subsequent arrival waves is upward or downward, and among each of the second and subsequent arrival waves, each of the arrival waves having an upward elevation angle, and the first arrival wave, And the theoretical value of the arrival time difference for an incoming wave with an upward angle of elevation rising as the first inconsistency, and the incoming elevation angle of the second and subsequent incoming waves is downward A degree of inconsistency between the arrival time difference between each of the first arrival waves and the first arrival wave and the theoretical value of the arrival time difference for the arrival wave having the downward angle of elevation is defined as a second inconsistency; A cost function calculating means for obtaining a sum of the first mismatch degree and the second mismatch degree as a cost;
A sound source estimation apparatus comprising: sound source position estimation means for estimating the virtual sound source position at which the cost calculated by the cost function calculation means is minimum as the position of the target sound source. A plurality of receivers are provided at the receiving position,
The sound source estimation apparatus according to claim 1, wherein the cost function calculation unit determines whether the arrival elevation angle is upward or downward based on outputs of the plurality of receivers. First and second receivers are provided at different positions in the depth direction of the receiving position,
The cost function calculating means determines whether the arrival angle of the incoming wave is upward or downward based on a difference in reception time of the same incoming wave at the first and second receivers. The sound source estimation apparatus according to claim 1. For each of the incoming waves detected by the first receiver, the detection timing;
Among the plurality of incoming waves detected by the second receiver, the difference between the detection timing and the detection timing of the first receiver is minimum, and the difference is less than or equal to a predetermined value. Determine that the incoming wave is the same as the incoming wave detected by the first receiver;
4. The sound source position estimation apparatus according to claim 3, wherein it is determined whether the arrival elevation angle is upward or downward based on a detection timing of incoming waves determined to be the same by the determination.   The predetermined value is calculated by calculating the difference in detection timing between two receivers based on the distance between the receivers and the speed of sound at the reception position. The sound source position estimation apparatus according to claim 4, wherein the sound source position estimation apparatus is a value for determining whether or not the maximum value or less.   5. The sound source position estimation apparatus according to claim 4, wherein only the observation value of the arrival time difference for the arriving waves determined to be the same is used for calculating the degree of inconsistency with the theoretical value of the arrival time difference.   The sound source position estimating apparatus according to claim 2, wherein the plurality of receivers constitute a vertical receiver array.   The theoretical value of the arrival time difference stored in the arrival time difference theoretical value storage means is calculated based on the depth of the reception position, the distance of the virtual sound source position, the depth, and the sound speed profile. The sound source position estimation apparatus according to claim 1. The cost function calculating means includes
Calculating the sum of the squares of the difference between the observed arrival time difference value and the theoretical arrival time difference value for an incoming wave having an upward angle of elevation as the first mismatch degree;
The sum of the squares of the difference between the observed arrival time difference value and the theoretical arrival time difference value for an incoming wave with the incoming elevation angle downward is calculated as the second mismatch degree. Sound source position estimation device.

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