JPH0119198B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic alarm device that detects the presence or absence of an intruder in a guarded area, for example, a guard room, and issues an alarm, and particularly relates to an ultrasonic alarm device that detects the presence or absence of an intruder in a guarded area, for example, a guarded room, and issues an alarm. The present invention relates to an ultrasonic alarm device that has been improved to prevent false alarms from being issued due to fluctuations in air conditions.

The presence or absence of an intruder in the restricted area is detected by emitting an ultrasonic pulse wave into the restricted area and comparing the pattern of the reflected wave with a reference pattern stored in advance in a storage means such as a memory. Although the ultrasonic alarm system for issuing alarms is well known, it is possible that the air within the warning area is disturbed by drafts or the activation of indoor/outdoor air conditioning equipment, etc.
If heat generating equipment placed in the restricted area creates layers with different air temperatures, the reflected waves of the ultrasonic pulse waves will interfere with each other, changing the reflection pattern and comparing it with the reference pattern. In this case, there is a problem in that an alarm is erroneously issued to notify the presence of an intruder. In order to avoid such inconveniences, the conventional ultrasonic alarm system using the above-mentioned method is designed to be used in a room inside a building where no outside air enters or exits the warning area, inside a nearly hermetically sealed window window, or for air conditioning in a room. There was a restriction that the equipment had to be used at selected times, such as at night, when it was not in operation.

Therefore, an object of the present invention is to eliminate the inconveniences associated with the conventional ultrasonic warning system described above, and to be able to accurately determine the presence or absence of an intruder and issue an alarm even if the air conditions within the warning area change. The purpose of the present invention is to provide an ultrasonic alarm device.

That is, in the ultrasonic warning system of the present invention, changes in the reflection pattern of ultrasonic reflected waves due to changes in air conditions within the warning area are faster on the time axis compared to changes in the reflection pattern caused by an intruder into the warning area. find out the points in which the progress is different, modify the reference pattern according to changes in air conditions when creating a reference pattern to be stored in advance in the storage means, and compare the presence or absence of an intruder based on this modified reference pattern. This is to prevent false alarms from occurring. Hereinafter, the present invention will be explained in more detail based on embodiments shown in the accompanying drawings.

FIG. 1 is a block circuit diagram of an ultrasonic alarm system implementing the method according to the present invention. In FIG. 1, the ultrasonic alarm device includes an ultrasonic transceiver 1 that transmits and receives ultrasonic pulse waves, a multiplier 2 connected to the ultrasonic transceiver 1, and a multiplier 2 connected to the ultrasonic transceiver 1. A connected rectifier 3, an A/D converter 4 connected after the rectifier 3, an arithmetic processing device 5 connected to the A/D converter 4, an alarm device 6 connected to the arithmetic processing device 5, and an ultrasonic wave. It is configured with an oscillator 7 connected to a transceiver 1 as a basic component. Although the connection relationship is not shown in FIG. 1, the transmitter 7 is driven by a command pulse sent by the arithmetic processing unit 5 to transmit a pulse signal. Now, when the arithmetic processing unit 5 sends oscillation command pulses to the oscillator 7 at fixed intervals, for example, at intervals of 0.5 seconds to 1.0 seconds, the oscillator 7 sends pulse signals to the ultrasonic transceiver 1 at the same intervals. Ultrasonic pulse waves are emitted from the ultrasonic transceiver 1 into the air within the caution area. This ultrasonic pulse wave is reflected from objects such as desks and shelves arranged in the security area, for example, walls of the room, and the reflected waves are received by the ultrasonic transmitter/receiver 1 again. . The reflected wave received by this transceiver 1 is converted into a corresponding electrical signal wave, and is converted into a corresponding electrical signal wave by a filter 2.
is applied to This filter 2 selectively amplifies the ultrasonic frequency component of the applied electrical signal wave and rectifies it by an AM (amplitude modulation) detection rectifier 3. The electrical signal wave corresponding to the rectified ultrasonic reflected wave is converted into a digital data form by the A/D converter 4, and is processed by the arithmetic processing unit 5. The digital data of the ultrasonic reflected waves input to the arithmetic processing unit 5 is sampled by the arithmetic processing unit 5 whose internal structure is shown within the dashed line frame in FIG. It is stored in the buffer memory 8 as a pattern. In this case, the sampling interval is selected to be, for example, 1 microsecond, and the sampling process is started after the above-mentioned oscillation command pulse is sent, for example.
It will be selected after 50 microseconds. In addition, in the arithmetic processing unit 5, statistical values such as the average value and deviation of past reflected wave patterns are statistically processed for each sample point by a microprocessor means consisting of various arithmetic circuits to be described later and a memory means. The system calculates this, corrects and creates a reference pattern for each sample point in case the normal reflected wave pattern changes due to changes in air conditions within the warning area, and stores the corrected reference pattern. . The stored modified reference pattern and the reflected wave pattern most recently stored in the buffer memory 8 are statistically compared again, and the results are determined based on the reflected wave pattern due to changes in air conditions and the presence of intruders in the warning area. Disturbances with the reflected wave pattern due to the presence or absence of an intruder are accurately determined, and only when an intruder is present, an alarm command signal is issued from the processing unit 5 to the alarm device 6, and the alarm device 6 causes, for example, an alarm buzzer to sound.
Now, the ultrasonic alarm system according to the present invention is characterized in that the above-mentioned modified reference pattern is created by a statistical processing method inside the arithmetic processing unit 5, and this characteristic point will be explained in detail below. do.

Now, in the embodiment of the ultrasonic alarm device according to the present invention, as shown in FIG.
1. Memories 12 and 13, and a discrimination circuit 14 are provided in the wiring relationship as shown in the figure. That is, the buffer memory 8, the average value calculation circuit 9, the standard deviation value calculation circuit 11, and the difference calculation circuit 10 constitute a compact microprocessor means. Now, as mentioned above, the buffer memory 8 stores the patterns of each reflected wave along the time axis, and the i-th reflected wave pattern is a graph in which the horizontal axis is time (t) and the vertical axis is the amplitude value (w). Now for the second
It is expressed as in figure a. In this case, each peak portion in the reflected wave pattern indicates that the ultrasonic wave was reflected by an object placed in the caution area, such as a desk. On the other hand, the reflected wave pattern stored in the buffer memory 8 is input to the average value calculation circuit 9, and in this calculation circuit 9, when the i-th reflected wave pattern is stored in the buffer memory 8, up to the (i-1)th The average pattern of the reflected wave patterns is calculated. Figure 2b shows the calculation circuit 9 with the horizontal axis representing time (t) and the vertical axis representing the average amplitude value ().
This shows the waveform of the calculation result. The calculation result of the calculation circuit 9 is then stored in the memory 12. In addition, the i-th reflected wave pattern stored in the buffer memory 8 and the (i-
The average pattern up to 1) is input to the difference calculation circuit 10, and the difference calculation circuit 10 calculates the absolute value of the difference between the two input patterns. FIG. 2c is a graph showing the calculation results of the difference calculation circuit 10, with the horizontal axis representing time (t) and the vertical axis representing the absolute value |-W|=σ of the difference between the two patterns. In addition, the i-th reflected wave pattern stored in the buffer memory 8 and the i-th reflected wave pattern stored in the memory 12 (i
The average pattern up to -1) and the calculation result of the difference calculation circuit 10 are input to the standard deviation value calculation circuit 11, and in this calculation circuit 11, (i-
1) The average of the deviations of the reflected wave patterns up to the th one is calculated as a pattern. FIG. 2d is a graph in which the horizontal axis represents time (t) and the vertical axis represents the average deviation, and shows the calculation results of the standard deviation value calculation circuit 11. The calculation result of the calculation circuit 11 is then stored in the memory 13. The average of the deviations stored in the memory 13 and the calculation result σ of the difference calculation circuit 10 are input to the discrimination circuit 14, and the ratio σ/ between the two is calculated. FIG. 2e is a graph showing the calculation results of the discrimination circuit 14, with time t plotted on the horizontal axis. As mentioned above, each ultrasonic pulse wave emitted into the air within the warning area will cause damage to pillars, desks, shelves, etc. within the area.
The light is reflected by a reflective object such as a wall, and depending on the position of the reflecting object, it generally exhibits a complex waveform pattern having a plurality of peak portions as shown in FIG. 2a. Furthermore, if there is an intruder in the warning area or if the air conditions change, the reflected wave pattern will further change in response. Therefore, in the present invention, each time the i-th reflected wave pattern is stored, (i
-1) Statistically process the past reflected wave patterns up to the i-th reflection pattern, and use data that statistically understands changes in air conditions occurring within the warning area as a reference pattern. The purpose is to clearly distinguish between the presence of an intruder and a change in air conditions by comparing and discriminating the wave pattern, and as a result, to accurately detect the former. Therefore, the second
The calculation results of the average value calculation circuit 9 shown in the graph of Figure b and the standard deviation value calculation circuit 1 shown in the graph of Figure 2 d
Using the calculation result of 1 as a reference pattern, further obtain the result of Fig. 2 e which is the ratio of the calculation result of Fig. 2 c obtained as the difference between Fig. 2 a and b and the reference pattern of Fig. 2 d. If this value is larger than a certain level, it is assumed that an intruder is present and an alarm is issued. Therefore, according to the method of the present invention, it is possible to accurately detect and determine the presence of an intruder by distinguishing between changes in the air conditions within the guarded area and the presence of an intruder. Next, each arithmetic circuit 9 of the arithmetic processing device 5,
A specific example of the arithmetic processing method performed in 10 and 11 will be explained in more detail.

First, in the average value calculation circuit 9, calculation processing is performed according to the following equation (1).

_i (t) = _i-1 (t) + (W _i (t)- _i-1 (t)) / c _o ... (1) In the above formula, i is the arrival number of the reflected wave pattern to device 5 , and c _o is a constant, which will be explained later. Further, W _i (t) indicates the i-th reflected wave pattern.

Next, in the difference calculation circuit 10, calculation processing is performed according to the following equation (2).

σ _i (t)=| _i-1 (t)−W _i (t)| (2) Further, in the standard deviation value calculation circuit 11, calculation processing is performed according to the following equation (3).

_i (t) = _i-1 (t) + (σ _i (t)- _i-1 (t))/C _n (3) c _n is a constant and will be explained below.

Here, when each arithmetic circuit 9, 10, 11 performs arithmetic processing according to the above arithmetic expressions (1), (2), and (3), a buffer memory for storing the i-th reflected wave pattern is used. It is only necessary to provide two storage means, the memory 12 for storing average patterns up to the 8th average pattern and the (i-1)th average pattern. Therefore, saving on the storage means can be achieved, and the microprocessor can have free space in the storage means in advance. If so, it becomes possible to create a reference pattern that takes into account not only changes in air conditions but also conditions for invasion by insects, small animals, etc.

Now, the constants c _{o and} c _n in equations (1) and (3) above are generally called smoothing indexes, and their meaning in statistical processing is the number of times in the past when data is taken in. It has the meaning of statistical time, which means whether statistical processing is performed. Generally, when air conditions change due to a draft in a warning area or a heating element placed indoors, the rise time of the change, that is, the time constant, is usually on the order of several minutes to over ten minutes. If an ultrasonic pulse wave is emitted within the area, for example, at a period of 1 second, the statistical time is selected to be sufficient and set to c _o =c _n =600.
In this way, the reference pattern will be created through statistical processing that takes into account the changes in air conditions within the warning area over the past ten minutes, and therefore the change in air conditions and the presence or absence of an intruder will be created. This will completely eliminate the drawback of confusing the two and issuing false alarms.

On the other hand, if a quiet state continues for a long time without any change in the air conditions within the warning area, and a sudden wind blows in when _i (t) has become sufficiently small, the air disturbance caused by the wind will occur. The time constant for the rise of is as short as several tens of seconds. Therefore c _o = c _n =
If it remains at 600, it will not be possible to follow the increase in _i (t), and therefore the value of the calculation result in the discrimination circuit 14 will exceed a certain level, and it will be erroneously determined that there is an intruder. In order to prevent such malfunctions, when the calculation result σ in the difference calculation circuit 10 is large, the value of c _n in the above equation (3) is set to about 10 to 20 in the calculation in the standard deviation value calculation circuit 11. If the above calculation result σ is small, the value of c _n in equation (3) is changed to about ₆₀₀ in the standard deviation calculation circuit 11 again. This is to delay the followability of _i (t) and create a reference pattern that takes into account changes in air conditions over a long statistical time. In addition,
The value of c _n can be changed by having the standard deviation value calculation circuit 11 maintain a function of switching the value of c _n according to the calculation result of the difference calculation circuit 10. Furthermore, it goes without saying that the value of c _o can also be changed at the same time as the value of c _n .

As can be understood from the above explanation, in the method of the present invention, every time the i-th reflected wave pattern is stored, the average pattern of the reflected wave patterns up to the (i-1)th and the average pattern up to the (i-1)th reflected wave pattern are stored. The standard pattern is created based on the average deviation of the reflection pattern of Malfunctions such as issuing an alarm due to changes in air conditions other than the presence of a person can be prevented, which not only improves the reliability of the alarm system itself, but also improves the reliability of the alarm system itself.
Many restrictions on the installation conditions of ultrasonic alarm devices will be relaxed, and versatility will be improved.

[Brief explanation of drawings]

FIG. 1 is a mechanical diagram showing an embodiment of the ultrasonic alarm device according to the present invention, and FIG. 2 is a pattern waveform diagram for explaining a reference pattern creation method in the ultrasonic alarm device according to the present invention. 1... Ultrasonic transceiver, 2... Multifilter, 3...
... Rectifier, 4 ... A/D converter, 5 ... Arithmetic processing unit, 6 ... Alarm device, 7 ... Oscillator.

Claims (1)

[Claims] 1. Emit an ultrasonic pulse wave to a guarded area, receive the reflected wave, compare the pattern of the reflected wave with a reference pattern, and if the two patterns are different, move to the guarded area. An ultrasonic alarm device that issues an intruder notification alarm includes a buffer memory that temporarily stores the pattern of the reflected wave, and an average pattern from the past multiple reflection patterns up to the reflected wave over a preselected statistical time. an average value calculation circuit for calculating; a first storage means coupled with the average value calculation circuit to store the average pattern as a reference pattern; and a first storage means coupled with the first storage means to store the average pattern and each of the reflection patterns. a difference calculation circuit that calculates the difference between
A standard deviation calculation circuit that calculates an average pattern of deviations of the reflected wave pattern over the statistical time from the reflection pattern, the average pattern, and the difference, and the standard deviation value calculation circuit are combined, and the deviation average pattern is calculated by combining the standard deviation calculation circuit and the standard deviation value calculation circuit. a second storage means for storing it as a reference pattern, and the difference calculation circuit is coupled with the standard deviation calculation circuit to adjust the statistical time according to the magnitude of the difference to modify and create the reference pattern. An ultrasonic alarm device featuring