JP2982756B2 - Signal detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal detection device suitable for use in a traffic accident recording device, for example, for detecting a transient signal (such as a collision sound) generated in a traffic accident.

[0002]

2. Description of the Related Art Conventionally, this kind of signal detection apparatus is used as a means for detecting a transient signal (such as a collision sound) generated in a traffic accident and recognizing the occurrence of the traffic accident, particularly in a traffic accident recording apparatus. I have. FIG. 9 is a block diagram showing a configuration of an example of a conventional signal detection device. The sensor unit 11 receives an audio signal, detects a signal exceeding a threshold from the received audio signal, and sends the detection signal to the outside. It has a detection unit 20 for outputting.

FIG. 10 is a schematic diagram showing a conventional detection method. When a transient signal generated at the time of a traffic accident is compared with a signal of a normal noise (such as a running sound of a vehicle), its signal level is very high. Set high and lower than the transient signal level at the time of a traffic accident.

[0004] In normal times, the signal level received by the sensor 11 is lower than the threshold value, so that the detecting unit 20 does not detect a transient signal. However, when an accident occurs, the received signal level is set. Since the detected threshold value is exceeded, the detection unit 20 detects a transient signal, recognizes the occurrence of a traffic accident, and outputs a detection signal to the outside.

Further, Japanese Patent Application Laid-Open Nos. 4-338900, 4-344421 or 6-203
No. 290 discloses a collision sound detection circuit or an impact sound detection sensor provided at a crossing point or the like. When an acoustic signal level higher than the threshold value is received, it is considered that an accident has occurred, and a detection signal is output. Used as a recording device that automatically records physical evidence of a traffic accident that occurs on a road by recording an acoustic signal for a certain period of time, or simultaneously recording an image signal that captures road conditions. An example is provided.

[0006]

The conventional signal detection device outputs a detection signal for all transient signals exceeding a predetermined threshold value. And construction site work (use of a pile driver, etc.) may occur in various places, for example, the problems with the traffic accident recording device mentioned above, such as transient signals that occur on roads other than In response to a traffic accident occurring outside the imaging range of an imaging device (such as a camera), there is a problem that a meaningless record in which nothing is recorded is left, and there is a problem that there are many false detections.

In view of the above problems, the present invention reduces the erroneous detection (detection of an unintended signal) by collecting data on the position where the transient signal has occurred in addition to the reception level when detecting the transient signal. The purpose is to make

[0008]

According to the present invention, there is provided a signal detecting apparatus comprising means for measuring a position where a transient signal is generated. That is,
The signal detection device of the present invention has a plurality of sensors, a sensor unit that receives an acoustic signal, a detection unit that detects a transient signal from the acoustic signal, and a sensor that detects a transient signal received by each sensor. A time difference measuring unit for measuring a reception time difference between the two, a position calculating unit for calculating a transient signal occurrence position from a sensor position registered in advance and a measured reception time difference, and setting an area to be detected based on an operator input. It comprises a detection area setting unit and a collation unit that checks whether the calculated occurrence position is within the detection area and outputs the occurrence position and a detection signal if the calculated occurrence position is within the detection area.

[0009]

FIG. 1 is a block diagram showing an embodiment of the present invention. The present invention provides a plurality of sensors 1, which are arranged at predetermined positions different from each other and receive an acoustic signal,
2, a sensor unit 10 having sensors 2, 3,
3, a detecting unit 20 for detecting a transient signal from the acoustic signal obtained from the acoustic signal, a time difference measuring unit 30 for measuring a receiving time difference between the sensors of the transient signals received by the sensors 1, 2, and 3, and A position calculation unit 40 that calculates a position at which a transient signal has occurred from the received time difference and a pre-registered sensor position, a detection region setting unit 50 having a display and an input device, and setting a region to be detected in advance, The transient signal generation position calculated by the position calculation unit 40 is compared with the detection region set by the detection region setting unit 50, and when the calculated transient signal generation position is included in the detection region, the detection signal and the transient signal generation are generated. And a collation unit 60 that outputs a position.

Next, the operation of the present invention will be described with reference to FIGS. FIG. 2 shows a positional relationship (an example) between the arrangement positions ( _PS1 , _PS2 , _PS3 ) of the sensors 1, 2, and 3 and the transient signal generation position P. FIG.
FIG. 3 shows time waveform diagrams of a few received signals.

Referring to FIG. 2, the transient signal generated at P propagates at the speed of sound and is received by each of the sensors 1, 2, and 3. Normally, since the propagation distance from the transient signal generation position P to each of the sensors 1, 2, and 3 is different, the reception time of the received signal is different for each sensor as shown in FIG. Each acoustic signal received by the sensor unit 10 is sent to the detection unit 20. The detection unit 20 detects a transient signal from each of the acoustic signals, and when the transient signal is detected, converts the detected signal and the acoustic signal into the time difference measurement unit 3.
Send to 0.

In the time difference measuring section 30, each of the sensors 1, 2,.
A process for measuring the difference in the reception time of the transient signal among the three is performed. The measured reception time difference between each sensor (△ t ₁₂ , △
t ₂₃ , Δt ₃₁ ) are sent to the position calculation unit 40. The position calculation unit 40 draws hyperbolas (12, 23, 31) at positions where the reception time difference shown in FIG. 4 is constant from the sensor positions (P _S1 , P _S2 , P _S3 ) and the reception time difference. Then, the transient signal generation position (P) is obtained from the intersection of these hyperbolas (12, 23, 31).

[0013] The transient signal generation position (P) is obtained as a point or a region. The calculated transient signal generation position (P) is sent to the collation unit 60. Detection area setting unit 50
Then, the detection area is set by prior registration by the operation of the operator. There are two types of setting methods. 1
One is a method of setting by drawing a detection area on a screen on which a sensor position and a road condition are displayed, and the other is a method of inputting mathematical formula information and the like and displaying the area on the screen. It is.

The set detection area is sent to the collating unit 60. The collation unit 60 performs collation based on the transient signal generation position and the detection region, and if the transient signal generation position (P) is within the detection region, sends out the detection signal and the transient signal generation position. If the transient signal occurrence position is not within the detection area, the received transient signal is regarded as having occurred in a place other than the predetermined area, and the detection signal and the position data are not output.

[0015]

[Example] When an accident occurs on the road to be monitored,
As a sensor unit 10 for detecting an impact sound (transient signal) received together with noise (such as a running sound of a vehicle), three microphones for converting an acoustic signal propagating in the air into an electric signal are arranged at predetermined positions. Is done. When the detection unit 20 that receives a signal from each microphone detects a transient signal (collision sound) having a predetermined level or more, the detection signal is sent to the time difference measurement unit 30.

The time difference measuring section 30 measures the time difference
Although the time of occurrence can be directly measured and the time difference can be measured from the time information, there is a method of measuring the reception time difference by correlation processing. FIG. 5 is a conceptual diagram of the time difference measurement by the correlation processing, in which a portion including a transient signal is cut out from the signal of the sensor 1 and the signal of the sensor 2 to delay the signal of the sensor 2 (Δt × (−4)). , Calculate the time average of the product of the signals of sensor 1 and sensor 2. Next, the delay time is changed for a fixed time (Δt), and a time average of the products is calculated in the same manner.

As described above, (△ t × (−4)) to (△ t ×
The correlation degree graph is obtained by calculating the time average of the products for (+4)). The reception time difference is a delay time at which the degree of correlation is the largest, and in the result of FIG. 5, Δt ₁₂ = Δt
× (+2). The same applies to the sensors 2 and 3 and the sensors 3 and 1, and Δt ₂₃ and Δt ₃₁ are measured. The obtained measurement result is output to the position calculation unit 40. In the position calculation unit 40, the sensor positions (P _S1 , P _S2 ,
P _S3 ) and the measured reception time difference (△ t ₁₂ , △ t ₂₃ , △
Using t ₃₁ ), a hyperbola having a certain reception time difference (distance difference) is obtained from the positions of the two sensors.

Here, the method of obtaining the hyperbola is shown in FIGS.
This will be described with reference to FIG. FIG. 6 is a diagram showing coordinate conversion. FIG. 7 is a diagram showing a method of obtaining a locus of a hyperbola. When calculating the trajectory of the hyperbola, the trajectory is calculated in the coordinate system f _{AB in} which the coordinates have been transformed. The coordinate system f _AB has the origin at the midpoint of the sensors A and B, and the sensors A and B are on the X ′ axis.

First, the coordinate conversion will be described. The conversion from the coordinate system f to the coordinate system f _AB is obtained by the following equation.

[0020]

(Equation 1) Further, the inverse transform is obtained by the following equation.

[0021]

(Equation 2) Next, a distance difference is obtained from the reception time difference of the transient signal. The distance difference d is obtained by the following equation.

D = △ t _AB × c (c: sound speed) Here, sensors 1, 2, and 3 corresponding to sensors A and B are set so that Δt _AB ≧ 0. For example, if Δt ₁₂ <0, Δt ₂₁ is set. That is, A = 2 and B = 1 are set. There are two types of trajectories having a constant distance difference depending on the value of d.

When d = 0, it becomes a perpendicular line passing through the middle point of the sensors A and B, and can be expressed by x '= 0.

When d ≠ 0, a hyperbola as shown in the following equation is obtained.

[0025]

(Equation 3) Next, the hyperbolic locus obtained on the coordinate f _AB is inversely transformed to the coordinate f. The operation of obtaining the hyperbolic trajectory is performed by a combination of the sensors to obtain three hyperbolic trajectories. As a result of the hyperbolic trajectory being obtained, the hyperbolas intersect, and the intersection indicates the position where the transient signal is generated (see FIG. 4). Here, three hyperbolas are obtained, and an intersection (occurrence position) is calculated using any two of the three hyperbolas. Because there is only one intersection in theory, there are various errors
When using two hyperbolas, three intersections are obtained. In order to avoid this, any two hyperbolas are selected, and the transient signal generation position is calculated from the intersection of those hyperbolas. As another method, there is a method of calculating an average position or a center of gravity position of three intersections or a region including all the intersections and setting the region as a transient signal generation position.

The calculated transient signal occurrence position is determined by the comparing unit 6.
Sent to 0. The detection area setting unit 50 includes a display for displaying a map and an input device (keyboard,
Mouse). Two setting methods are possible. One is that when a condition for a detection area is input, the detection area is displayed on a map. For example, when a condition of a detection area is input to an intersection as shown in FIG. 8 by a mathematical expression, the area is displayed on the intersection map. Then, the input condition of the detection area is sent to the matching unit 60. In another method, when a detection area is drawn on the displayed map, the conditions of the drawn detection area are calculated and sent to the matching unit 60. For example, as shown in FIG. 8, the detection area is drawn while looking at the display screen, and the condition of the detection area is calculated from the result. Further, the detection area setting unit 50 can also set a plurality of detection areas at the same time.

The collation unit 60 outputs a position result and a detection signal if the measured position satisfies the condition of the detection area. Further, when the measured position is near the boundary of the detection area, data indicating the boundary may be output together. When a plurality of detection areas are set, information about which detection area is also output.

In the present embodiment, the number of sensors has been described as three, but there is no problem if the number of sensors is four or more. This is because the number of hyperbolas that can be drawn when the number of sensors is n is (n-1) + (n-
2) +... + (Nn), and if two hyperbolas are drawn, the position can be basically obtained. Further, depending on the conditions for setting the installation location and the detection area, there may be a case where two pieces can be used. For example, although only one hyperbola can be drawn with two sensors, a transient signal in a place other than on a road does not usually occur in a tunnel or the like. Therefore, the intersection of the hyperbola and the road is the position where the transient signal is generated.

[0029]

As described above, according to the present invention, by using position information in addition to level information, it is possible to reduce the detection of a transient signal not required by the operator. Further, by providing several detection regions, it is possible to classify signals by position. For example, it can be determined whether the accident on the road is an up line or a down line.

[0030]

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining a relationship between each sensor position and a transient signal generation position according to the present invention.

FIG. 3 is a time waveform chart of a reception signal of each sensor.

FIG. 4 is a conceptual diagram of a method for calculating a transient signal generation position.

FIG. 5 is a conceptual diagram of time difference measurement by correlation processing.

FIG. 6 is a diagram showing coordinate conversion.

FIG. 7 is a diagram illustrating a method of obtaining a locus of a hyperbola.

FIG. 8 is a diagram illustrating a method of setting a detection area.

FIG. 9 is a block diagram showing a conventional example.

FIG. 10 is a schematic diagram showing a conventional detection method.

[Explanation of symbols]

 1, 2, 3 acoustic sensor 10, 11 sensor unit 20 detection unit 30 time difference measurement unit 40 position calculation unit 50 detection area setting unit 60 collation unit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-205581 (JP, A) JP-A-10-227849 (JP, A) JP-A 8-263785 (JP, A) JP-A 8- 116528 (JP, A) JP-A-6-203290 (JP, A) JP-A-4-338900 (JP, A) JP-A-3-65799 (JP, A) Japanese Utility Model Laid-Open No. 60-143374 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) G01S 5/18-5/30 G08G 1/00

Claims (8)

(57) [Claims] 1. A sensor unit having a plurality of sensors arranged at predetermined positions different from each other and receiving an acoustic signal; a detecting unit detecting a transient signal from an acoustic signal received by each of the sensors; A time difference measurement unit that measures a reception time difference between the sensors of the transient signal received by each sensor, and a position calculation unit that calculates a position where the transient signal is generated from the measured reception time difference and the arrangement position of each sensor. And a detection area setting unit for setting an area to be detected, and comparing the transient signal generation position calculated by the position calculation unit with the detection area set by the detection area setting unit, and calculating the calculated transient signal generation. A signal detection device comprising: a collation unit that outputs a detection signal and a transient signal occurrence position when the position is included in a detection area. 2. The signal detection apparatus according to claim 1, wherein the detection range is a predetermined range on a road, and the sensors are arranged around the predetermined range. 3. The apparatus according to claim 1, wherein the time difference measuring section calculates a reception time difference between the sensors by performing a correlation process on the transient signal received by each of the sensors.
The signal detection device according to claim 1. 4. The position calculation unit obtains a plurality of hyperbolas with a constant reception time difference between the sensors based on the arrangement position of the sensors and the reception time difference, and determines a transition point of the hyperbolas from a transient signal. 2. The signal detection device according to claim 1, wherein the generation position is obtained. 5. The signal detection device according to claim 4, wherein the position calculation unit outputs an average position or a center of gravity of intersections of the plurality of hyperbolas as the transient signal generation position. 6. The signal detection device according to claim 4, wherein the position calculation unit outputs a region including all intersections of the plurality of hyperbolas as a transient signal generation position. 7. The signal detection device according to claim 1, wherein a plurality of different areas are set as the detection areas. 8. The apparatus according to claim 1, wherein the detection area setting section has an input device and a display device, and further includes means for setting a detection area based on an operator's input.
The signal detection device according to claim 1.