JP3810332B2 - Accident sound detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an accident sound detection apparatus for efficiently detecting only accident sounds from traffic sounds and accident sounds (including accident sounds such as collisions and sudden brake sounds that lead to accidents) at intersections and the like. .
[0002]
[Prior art]
In general, since many traffic accidents occur at intersections, a traffic accident status recording apparatus that records the status of accidents has been conventionally considered.
FIG. 10 is a block diagram showing a conventional traffic accident situation recording apparatus disclosed in, for example, Japanese Patent Laid-Open No. 4-338900.
In FIG. 10, 1 and 4 are traffic lights, 1B, 1Y, 1R, 4B, 4Y, 4R are signal lights, 2B, 2Y, 2R are signal lines, 3 is a signal light flashing device, 5 is a signal light symbol generator, and 6 is a time letter. A generating unit, 7 is an adding unit, 8 is an imaging device, 9 is an endless recording device, 10 is an ambient sound detecting device, 11 is a collision sound detecting circuit, 12 is a recording control device, and 13 is a magnetic recording / reproducing device.
[0003]
Here, the part that detects the accident sound is the ambient sound detection device 10 and the collision sound detection circuit 11. That is, the ambient sound detection device 10 detects an acoustic signal and sends it to the collision sound detection circuit 11. The collision sound detection circuit 11 determines whether or not the detected acoustic signal is a vehicle collision sound. When it is determined as a collision sound, the collision sound detection signal is sent to the recording control device 12.
In the collision sound detection circuit 11, whether or not the detected traffic sound is an accident (collision) sound is compared with the level of the input acoustic signal and a predetermined threshold value, and the level becomes equal to or higher than the threshold value. In the event of an accident. As a countermeasure against malfunction, a directional microphone is used for the ambient sound detection device 10, and a band elimination filter is provided in the path of the acoustic signal.
[0004]
[Problems to be solved by the invention]
By the way, in the collision sound detection circuit described in the above publication, a level comparison is made between an acoustic signal detected in the determination of the collision sound and a preset fixed threshold value. However, in general traffic sounds, there are many sounds with high levels other than accident sounds, such as sudden braking sounds, horn sounds, and runaway sounds. For this reason, in the method of comparing the level of the detected acoustic signal with a fixed threshold value, there is a problem that many other traffic sounds are determined as accident sounds in addition to the actual accident sounds.
In addition, there is a problem that information regarding the type of whether the detected accident sound is a collision sound or a repetitive impact sound cannot be obtained.
[0005]
The present invention has been made to solve the above-mentioned problems, and does not use a signal level threshold for discrimination of accident sound, but normalizes and compares the waveform of the captured signal such as accident sound. It is an object of the present invention to provide an accident sound detection apparatus that can discriminate repetitive impact sounds from actual accident sounds by binarizing and improve the detection ability of accident sounds.
[0006]
[Means for Solving the Problems]
An accident sound detection device according to the invention of claim 1 is an accident sound detection device for detecting an accident sound using an external acoustic signal, the accident sound capturing means for capturing the accident sound, and the accident Repetitive impact sound determination calculating means for determining a repetitive impact sound from the output signal from the sound capturing means, and the above-mentioned accident if the determination result of the repetitive shock sound determination calculating means is a repetitive shock sound Repetitive impact sound removing means for excluding the repetitive impact sound from the accident sound captured by the sound capturing means.
[0007]
In the accident sound detection apparatus according to the second aspect of the invention, the accident sound capturing means converts a waveform shaping circuit for shaping the waveform of the external acoustic signal, and converts an analog signal of the waveform shaping circuit into a digital signal. Comparing the A / D converter, the difference calculation means for extracting the difference signal from the output signal from the A / D converter, the difference signal from the difference calculation means and a reference difference value set in advance; A comparison circuit for generating a trigger signal in accordance with the comparison result; and a switch for taking the output signal from the A / D converter into the repetitive impact sound determination calculation means based on the trigger signal from the comparison circuit. Is.
[0008]
According to a third aspect of the present invention, there is provided an accident sound detection apparatus in which the repetitive impact sound determination calculation means normalizes a level of an output signal from the A / D converter, and the normalization means A comparison means for removing a constant level signal from the digitized signal, a binarization means for binarizing the output signal from the comparison means, and a repetitive impact sound from the output signal from the binarization means. Repetitive impact sound determining means for determining and outputting.
[0009]
According to a fourth aspect of the present invention, there is provided the accident sound detection device, wherein the repetitive impact sound determination means captures the accident sound capture means when the evaluation value based on the output signal of the binarization means is smaller than a predetermined value. The accident sound is determined to be a repetitive impact sound.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a functional block diagram showing Embodiment 1 of the present invention.
In FIG. 1, 20 is an accident sound capturing means, 100 is an acoustic input signal from the ambient sound detection device 10 (see FIG. 10), 110 is an output signal of the accident sound capturing means 20, and 30 is an accident sound capturing means 20. Repetitive impact sound determination calculation means for determining a repetitive impact sound from the output signal 110 from the output signal, 120 is an output signal of the repetitive shock sound determination calculation means 30, and 40 is an output signal of the repetitive impact sound determination calculation means 30. 120 is a repetitive impact sound removing means for removing a repetitive impact sound such as a motorcycle sound from the output signal 110 of the accident sound capturing means 20 based on 120, and 130 is an output signal of the repetitive impact sound removing means 40.
[0011]
FIG. 2 is a circuit configuration diagram showing an example of a specific circuit configuration of the accident sound capturing means 20.
In FIG. 2, 21 is a waveform shaping circuit for shaping the waveform of the external acoustic input signal 100, 101 is an output signal from the waveform shaping circuit 21, and 22 is an output signal 101 from the waveform shaping circuit 21 that is converted from an analog signal to a digital signal. A is a digital output signal of the A / D converter 22, 23 is a difference calculation means for extracting a difference signal from the digital output signal 102, and 103 is a difference from the difference calculation means 23. 25, a reference difference value generation circuit for generating a difference signal (reference difference value) at a reference level, 24, a difference signal 103 from the difference calculation means 23, and a reference difference value from the reference difference value generation circuit 25 Is a comparison circuit that generates an output signal 104 when the difference signal 103 from the difference calculation means 23 is larger than a set reference difference value. 26 is a switch for taking in the output signal 102 of the A / D converter 22 by using the output signal 104 from the comparison circuit 24 as a trigger signal, and 110 is an output signal (OUT) taken in by the switch 26.
[0012]
FIG. 3 is a circuit configuration diagram showing an example of a specific circuit configuration of the repetitive impact sound determination calculation means 30.
In FIG. 3, 31 is a normalizing means for normalizing the level of the output signal 110 from the accident sound capturing means 20, 32 is a comparing means for removing a constant level signal of the signal normalized by the normalizing means 31, 33 Is a binarization means for separating the output signal from the comparison means 32 into a logic level “1” and “0”, and 34 is a judgment of a repetitive impact sound from the output signal from the binarization means 33. The repetitive impact sound determination means outputs as the output signal 120.
[0013]
Of course, the comparing means 32 and the binarizing means 33 may be integrated into the binarizing means 33. In this case, binarization can be realized by setting all values equal to or higher than the reference value (for example, 0.2) to “1” and all the values below “0”.
[0014]
Next, the operation will be described with reference to FIGS.
First, the case of traffic sounds other than accident sounds, such as motorcycle passing sounds, will be described with reference to FIGS.
Now, when an acoustic input signal 100 is generated and input to the accident sound capturing means 20 when an accident occurs, an unnecessary signal component is removed by the waveform shaping circuit 21 and an output signal 101 is generated.
The output signal 101 is converted from an analog signal to a digital signal 102 by an A / D converter 22. The output digital signal 102 is input to the difference calculation means 23, and the difference signal 103 of the digital output signal 102 is output from the difference calculation means 23. The difference signal 103 generally represents a change in the signal level, and a larger signal level is generated as there is a sudden level change. Conversely, if the level change is small even if the signal level is large, the level is small. Therefore, for example, when a sudden phenomenon occurs such as when an accident occurs, the difference signal 103 shows a large level change.
[0015]
Therefore, a reference difference value as a reference is generated in advance by the reference difference value generation circuit 25, and the difference signal 103 and the reference difference value are compared using the comparison circuit 24. When the difference signal 103 is larger than the reference difference value, it is determined that a traffic accident sound whose signal level changes rapidly is generated, and the output signal 104 is generated as a trigger signal. The switch 26 is turned on by the output signal 104 from the comparison circuit 24 to take in the output signal 102 of the A / D converter 22 and input to the repetitive impact sound determination calculation means 30 as the output signal 110.
[0016]
The normalization means 31 of the repetitive impact sound determination calculation means 30 normalizes the level of the captured output signal 110 and outputs, for example, a repetitive impact sound capture waveform signal as shown in FIG. To do.
The comparison means 32 provides a reference value in order to remove a signal at a certain level, outputs only a signal that is equal to or higher than the reference value, and does not substantially output a signal that is less than the reference value. That is, for example, if the reference value is 0.2 in FIG.
[0017]
FIG. 5 shows a signal waveform output by the comparison means 32 in this way, and the waveform is a waveform in which only a signal equal to or higher than the reference value is left.
FIG. 6 shows a pattern obtained by binarizing the waveform of FIG. 5 by the binarizing means 33. In this evaluation pattern, the evaluation value = 0.062 is obtained by dividing the sum of the levels at “1” by the time width of FIG. 6 and indicates the area occupancy ratio of the portion at which the level is “1”. is there.
[0018]
Next, a normal case where the traffic sound is an accident sound will be described with reference to FIGS.
The normalization means 31 of the repetitive impact sound determination calculation means 30 normalizes the level of the captured output signal 110 and outputs, for example, a repetitive impact sound capture waveform signal as shown in FIG. To do.
The comparison means 32 provides a reference value in order to remove a signal at a certain level, outputs only a signal that is equal to or higher than the reference value, and does not substantially output a signal that is less than the reference value. That is, for example, if the reference value is 0.2 in FIG. 7, a signal with a level of 0.2 or higher is output, and all signals with a level lower than 0.2 are set to 0.
[0019]
FIG. 8 shows a signal waveform output by the comparison means 32 in this way, and the waveform is a waveform in which only a signal equal to or higher than the reference value is left.
FIG. 9 shows a pattern obtained by binarizing the waveform of FIG. 8 by the binarizing means 33. In this evaluation pattern, the evaluation value = 0.29 is obtained by dividing the sum of the levels at “1” by the time width in FIG. 9 and indicates the area occupancy of the portion at which the level is “1”. is there.
[0020]
Here, as can be seen from the comparison between FIG. 6 and FIG. 9, it is clear that the traffic sound other than the accident sound of FIG. 6 such as a motorcycle passing sound and the normal case where the traffic sound of FIG. 9 is an accident sound. There is a difference in the evaluation value, and it can be seen that the evaluation value is smaller in the case of a motorcycle passing sound than in the normal case.
[0021]
Therefore, the repetitive impact sound judging means 34 takes in the output signal from the binarizing means 33, judges whether the evaluation value of the fetched output signal is larger than a predetermined judgment value, for example, 0.1, and takes it in. If the evaluation value of the output signal is smaller than a predetermined judgment value, for example, 0.1, this is judged as a repetitive impact sound, that is, a motorcycle passing sound, and the output signal 120 is output to the repetitive impact sound removing means 40. To do.
The repetitive impact sound removing means 40 removes the output signal 110 from the accident sound capturing means 40 based on the output signal 120 at this time.
[0022]
On the other hand, in the repetitive impact sound determination means 34, when the evaluation value of the output signal taken from the binarization means 33 is larger than a predetermined determination value, for example, 0.1, this is not a repetitive impact sound. It is determined that the sound is an accident sound, and an output signal 120 is output to the repetitive impact sound removing means 40.
The repetitive impact sound removing means 40 outputs the output signal 110 from the accident sound capturing means 40 as it is based on the output signal 120 at this time.
[0023]
In this way, in the present embodiment, in order to distinguish repetitive impact sounds from actual accident sounds in the captured acoustic signals such as accident sounds, the level of the captured signals is standardized. , Make a comparison to remove the signal of a certain level, binarize the comparison result, determine the repetitive impact sound, and based on the determination result, pick the repetitive impact sound from the accident sound Since it has been removed, it is possible to discriminate motorcycle passing sounds that could not be identified so far, and it is possible to efficiently detect only accident sounds and improve the detection ability of accident sounds.
[0024]
【The invention's effect】
As described above, according to the invention of claim 1, an accident sound detection device for detecting an accident sound using an external acoustic signal, the accident sound capturing means for capturing the accident sound, The repetitive impact sound determination calculating means for determining a repetitive impact sound from the output signal from the accident sound capturing means, and the determination result of the repetitive shock sound determination calculating means is a repetitive impact sound Has a repetitive impact sound removing means for excluding the repetitive impact sound from the accident sound captured by the accident sound capturing means. It is possible to discriminate the impact sound having a characteristic, and it is possible to efficiently detect only the accident sound and improve the detection ability of the accident sound.
[0025]
According to a second aspect of the present invention, the accident sound capturing means includes a waveform shaping circuit for shaping the waveform of the external acoustic signal, and an A / A for converting the analog signal of the waveform shaping circuit into a digital signal. The D converter, the difference calculation means for extracting the difference signal from the output signal from the A / D converter, the difference signal from the difference calculation means and the reference difference value set in advance are compared, and the comparison Since it has a comparison circuit that generates a trigger signal according to the result, and a switch that takes the output signal from the A / D converter into the repetitive impact sound determination calculation means based on the trigger signal from the comparison circuit, There is an effect that only the accident sound can be efficiently detected.
[0026]
According to a third aspect of the invention, the repetitive impact sound determination calculation means is normalized by the normalization means for normalizing the level of the output signal from the A / D converter, and the normalization means. Comparing means for removing a constant level signal from the detected signal, binarizing means for binarizing the output signal from the comparing means, and determining a repetitive impact sound from the output signal from the binarizing means. Therefore, it is possible to identify a repetitive impact sound and contribute to an improvement in the ability to detect an accident sound.
[0027]
According to a fourth aspect of the present invention, the repetitive impact sound determining means is configured to detect the accident sound captured by the accident sound capturing means when the evaluation value based on the output signal of the binarizing means is smaller than a predetermined value. Is determined to be a repetitive impact sound, there is an effect that a repetitive shock sound can be determined efficiently and reliably.
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing a first embodiment of the present invention.
FIG. 2 is a block configuration diagram illustrating an example of an accident sound capturing unit according to Embodiment 1 of the present invention.
FIG. 3 is a block diagram showing an example of repetitive impact sound determination calculation means according to Embodiment 1 of the present invention.
FIG. 4 is a diagram showing an output waveform of traffic sound other than accident sound of the normalizing means in Embodiment 1 of the present invention.
FIG. 5 is a diagram showing an output waveform of traffic sound other than accident sound of the comparing means in Embodiment 1 of the present invention.
FIG. 6 is a diagram showing an output waveform of traffic sound other than accident sound of the binarization means in Embodiment 1 of the present invention.
FIG. 7 is a diagram showing a normal output waveform which is an accident sound of the normalizing means in Embodiment 1 of the present invention.
FIG. 8 is a diagram showing a normal output waveform which is an accident sound of the comparison means in the first embodiment of the present invention.
FIG. 9 is a diagram showing a normal output waveform which is an accident sound of the binarization means in Embodiment 1 of the present invention.
FIG. 10 is a block diagram showing a conventional traffic accident situation recording apparatus.
[Explanation of symbols]
20 accident sound capturing means, 21 waveform shaping circuit, 22 A / D converter, 23 difference calculation means, 24 comparison circuit, 25 reference difference value generation circuit, 26 switch, 30 repetitive impact sound determination calculation means, 31 standardization Means, 32 comparison means, 33 binarization means, 34 repetitive impact sound determination means, 40 repetitive impact sound removal means.

Claims (4)

An accident sound detection device for detecting an accident sound using an external acoustic signal,
Accident sound capturing means for capturing the accident sound,
Repetitive impact sound determination calculating means for determining a repetitive impact sound from the output signal from the accident sound capturing means;
Repetitive impact sound removing means for excluding the repetitive impact sound from the accident sound captured by the accident sound capturing means when the determination result of the repetitive impact sound determination calculating means is a repetitive impact sound; An accident sound detection apparatus comprising: The accident sound capturing means includes a waveform shaping circuit that shapes the waveform of the external acoustic signal, an A / D converter that converts an analog signal of the waveform shaping circuit into a digital signal, and the A / D converter. A difference calculating means for extracting a difference signal from an output signal from the comparator, a comparison circuit for comparing the difference signal from the difference calculating means with a reference difference value set in advance and generating a trigger signal according to the comparison result 2. An accident sound detection according to claim 1, further comprising: a switch that takes in an output signal from the A / D converter to the repetitive impact sound determination calculation means based on a trigger signal from the comparison circuit. apparatus. The repetitive impact sound determination calculation means includes a normalization means for normalizing the level of the output signal from the A / D converter, and a comparison means for removing a constant level signal of the signal normalized by the normalization means. And binarizing means for binarizing the output signal from the comparing means; and repetitive impact sound determining means for determining and outputting a repetitive impact sound from the output signal from the binarizing means. The accident sound detection device according to claim 2, wherein the accident sound detection device is provided. The repetitive impact sound determining means determines that the accident sound captured by the accident sound capturing means is a repetitive impact sound when the evaluation value based on the output signal of the binarizing means is smaller than a predetermined value. The accident sound detection device according to claim 3, wherein:

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