JP2006350855A - Security device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a security device capable securely and quickly detecting an abnormal state even though a sensor output level in a steady state fluctuates due to disturbance or the like. <P>SOLUTION: An output of a sensor 1 such as a vibration sensor is amplified by an amplifier 2, smoothed by a smoothing filter 3 and subsequently converted into a digital value by an A-D converter 4. A threshold generating part 5 stores an output of the A-D converter, calculates the average value of data of N times immediately before the stored output and sets a value obtained by raising the average value by a prescribed amount as a threshold of this time in a comparison determining part 6. By this, when an output value of the sensor increases and decreases, a threshold also increases and decreases, and in the case of a gentle fluctuation in a steady state, the threshold can be followed and an output value of the A-D converter does not exceed the threshold. Meanwhile, since a fluctuation in a sensor output based on a theft action or the like is performed in a short period, the threshold cannot be followed, and the output value of the A-D converter exceeds the threshold so that an abnormal state can be detected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to other security devices for vehicles.

  There are various types of vehicle security devices. One type of the security device is the invention disclosed in Patent Document 1. The invention disclosed in Patent Document 1 is a method of determining a theft in a crime prevention device that detects an anomaly by an impact sensor or a sound sensor that detects an impact or sound acting on an object that should be prevented from theft, and performs crime prevention. . Specifically, the output wave from the sensor sets a predetermined threshold value for noise removal. Then, (1) the slope of the waveform rising part when the level of the output wave from the sensor output exceeds the threshold value, and the waveform rising part when it goes to the peak value, and (2) time-sharing the waveform rising part when it goes to the peak value Then, the change amount for each time division is detected, and when any change amount is larger than a preset specified change amount, or (3) required to reach the peak value after exceeding a predetermined threshold value The arrival time is detected, and when the required arrival time is shorter than a predetermined arrival time set in advance, it is determined that the waveform is due to theft, and a predetermined alarm is issued.

Japanese Patent No. 3290160

  However, such conventional vehicle security devices have the following problems. That is, all the detection of the theft disclosed in the above-described conventional apparatus is performed based on a change after exceeding a threshold set for noise removal. Therefore, for example, when the threshold value Th is set as shown in FIG. 1, the noise level of the output wave from the sensor output generated in the normal state is less than the threshold value Th as shown in FIG. The line segment connecting the point where the level of the output wave exceeds the threshold and the peak value is “L1”, and the theft can be detected by any of the three methods described above.

  However, since the noise level actually fluctuates due to the influence of disturbance such as temperature change, rain, and other factors, for example, when the noise level becomes higher than the set threshold as shown in FIG. The line connecting the point where the level of the output wave exceeds the threshold and the peak value becomes “L2”, and the slope becomes low and takes time. The act cannot be detected. Further, each noise peak itself may be determined as a peak value, and may be erroneously determined as having been stolen. The same phenomenon occurs, for example, in a malfunction caused by rain or other weather in home security or the like.

  SUMMARY OF THE INVENTION The present invention solves the above-described problems, and an object of the present invention is to provide a security device that can reliably and quickly detect an abnormality without malfunction even if the sensor output level (noise level) in a steady state varies due to disturbance or the like. Is to provide.

  In order to achieve the above object, the security device according to the present invention determines whether or not the value of a signal based on a sensor and an output signal of the sensor exceeds a set threshold value, and exceeds the threshold value. And a threshold value setting unit for setting the threshold value for the comparison and determination unit. The threshold value setting unit acquires a signal value based on an output signal of the sensor. It is configured to have a function of temporarily storing and generating a threshold value based on a plurality of recently stored temporary data.

  The recent plurality of data may include at least a signal value based on the sensor output signal acquired this time. Of course, in the present invention, the threshold value may be set without necessarily using the signal value based on the output signal of the sensor acquired this time, and the most recent data may be N consecutive (this is the most). However, the threshold value may be set based on data that is appropriately dispersed.

  More specifically, it comprises a smoothing processing means and an A / D conversion means for A / D converting the output of the smoothing processing means, and the value of the signal based on the output signal of the sensor is the output signal or The signal processed into the output signal is smoothed by the smoothing processing means, and the smoothed signal is converted into a digital value by the A / D conversion means. The present invention is realized in the first embodiment.

  Further, it comprises A / D conversion means for A / D converting an output signal of the sensor or a signal processed into the output signal, and the threshold setting means is based on a digital waveform signal given from the A / D conversion means, It may be configured to have a function of extracting a maximum value and a minimum value and generating a threshold value based on the maximum value and a threshold value based on the minimum value, respectively. The present invention is realized in the second embodiment.

  Further, the threshold setting means includes a low-pass filter for filtering the output signal or an analog signal processed into the output signal, and a level shift means for shifting the output signal of the low-pass filter by a predetermined margin. It can also be prepared. The present invention is realized in the third embodiment.

  When observing the reaction of impact sensors and other sensors used in automobile security, sudden changes appear when an impact is actually applied to the vehicle, but the output level slowly changes in the event of a malfunction due to a sound vehicle etc. There is a difference. Therefore, according to the present invention, since the threshold value changes with a certain margin depending on the noise level, the reaction can be detected even under such conditions. In addition, since it is intended to remove a slow change because it is not a normal reaction, it can be applied to a case where the noise level of the sensor changes due to a change over time, an environmental change, or the like, so that it can be applied to any sensor other than an impact sensor.

  As described above, in the security device according to the present invention, even if the sensor output level (noise level) in the steady state fluctuates due to disturbance or the like, an abnormality can be detected reliably and quickly without malfunction.

  FIG. 2 shows a first embodiment of the present invention. Although this embodiment shows an example in which the present invention is applied to a vehicular security device as an embodiment of a security device, the basic system configuration can be similarly applied to home security and other security devices. This is the same in other embodiments.

  First, the security device (vehicle security device) includes a sensor 1, an amplifier 2, a smoothing filter 3, an A / D converter 4, a threshold generation unit 5, and a comparison determination unit 6 in order from the signal input side. I have.

  The sensor 1 is a sensor for detecting theft and other abnormalities. For example, a vibration sensor, an acceleration sensor, a sound pressure sensor, a Doppler sensor, and other various sensors can be used. These sensors are set at appropriate positions in the vehicle and other places. The vibration sensor and the acceleration sensor can detect a vibration / impact on the vehicle. The sound pressure sensor can detect fluctuations in the pressure in the passenger compartment as the door is opened and closed, and can infer human intrusion. The Doppler sensor detects the approach / separation of a person, and when a third party is wandering around the vehicle, it can be presumed to be an abnormal action (for example, the inside of the vehicle interior is colored). Of course, the sensors are not limited to those exemplified above, and various sensors can be used.

  The sensor output (vibration waveform signal) output from the sensor 1 is input to the amplifier 2. Usually, since the waveform level of the sensor output is small, the amplification process is performed by the amplifier 2 to increase the level difference of the output signal in accordance with the presence or absence of abnormality, and the determination process in the subsequent stage is facilitated. The amplified signal (amplified signal) output from the amplifier 2 is given to the smoothing filter 3.

  The smoothing filter 3 smoothes the given amplified signal. That is, since the sensor output includes a noise component, the sensor output has a high-frequency vibration waveform, and thus the amplified signal also has a vibration waveform having a larger amplitude than the sensor output (see FIG. 3A). Therefore, by passing through the smoothing filter 3, a smoothed signal composed of an envelope connecting the peak values of the amplified signal is generated (see FIG. 3B).

  The A / D converter 4 converts the smoothed signal (analog signal) into a discrete digital value (see FIG. 3C). In this example, the level is converted to a positive integer such as 0 → 1 → 2 → 3 →. Of course, the conversion to a digital value is not limited to such a positive integer, and may be a value having a decimal point or a discrete value other than that. In short, it is sufficient if the level can be divided.

The output of the A / D converter 4 is given to the threshold value generation unit 5 and the comparison determination unit 6, respectively. The threshold generation unit 5 has a temporary storage memory inside, stores and holds at least the past N-1 data (the output value from the A / D converter 4), and stores the previous N-1 previous data. Then, a threshold value is generated based on a total of N pieces of data acquired this time. Specifically, assuming that the latest data acquired this time is the i-th data (D (i)) currently acquired,
D (i-N-2): Data before N-1 times ...
D (i-3): Data before 3 times D (i-2): Data before 2 times D (i-1): At least data before 1 time is stored. Of course, the data before and before N times may be stored and retained, and the data (D (i)) acquired this time is not prevented from being stored in the temporary storage memory. Actually, since the data (D (i)) acquired this time is used when generating a threshold value for the next (i + 1) th acquired data, it may be stored in a temporary storage memory.

In this embodiment, a simple average is obtained using N pieces of data. If N = 4, the average value is obtained by the following equation.

(D (i) + D (i-1) + D (i-2) + D (i-3)) / 4

  A certain margin (margin value) S is raised with respect to the nearest N (four) average values including the current value obtained as described above (in this embodiment, simply adding: + S). As a result, the current threshold value is generated. This increase is the sensitivity.

Therefore, the threshold Th (i) when S = 2 is
Th (i) = ((D (i) + D (i-1) + D (i-2) + D (i-3)) / 4) +2
It becomes.

  Then, the threshold value Th (i) obtained in this way is given to the comparison determination unit 6. In addition to the processing shown in the present embodiment, for example, various methods other than IIR, FIR, and the like can be used as the filtering process in which the change becomes gentle with N pieces of data. In the present embodiment, S = 2, but the present invention is not limited to this.

  The comparison determination unit 6 compares the i-th data (D (i)) given from the A / D converter 4 with the i-th threshold Th (i) given from the threshold generation unit 5, and When the data D (i) is larger than (or “more than”) the threshold Th (i), it is determined that the theft is occurring. As described above, when the threshold value Th (i) is obtained, the data D (i) to be inspected this time is also used because, for example, suddenly generated noise or noise of a certain level until then is used. Even when the noise level gradually increases due to a disturbance when it occurs, the threshold value can be shifted slightly higher by including the data that is the change point. This is because erroneous detection due to level fluctuations can be prevented. And by making S small, the change of the signal based on an actual theft act can be detected rapidly, and an alarm etc. can be emitted.

  Next, the operation of the above-described embodiment will be described with a specific example. For example, assuming that the output of the amplifier 2 is as shown in FIG. 3A, as described above, the output of the smoothing filter 3 is as shown in FIG. Here, the peak P1 in FIG. 3 is a waveform based on the theft, and a sudden level change occurs.

  When the smoothed data is digitized (sampled) by the A / D converter 4 at a predetermined sampling period, the result is as shown in FIG. At this time, if the value of each data changes as 2, 2, 2,..., 2, 5, 9, 4, 2, 2, 2, 2,. As shown in FIG. 3D, (S = 2) changes to 4, 4, 4,..., 4, 5, 7, 7, 7, 6, 5, 4,. Thus, it changes following the level of the given data.

  Then, the comparison / determination unit 5 compares the output of the A / D converter 3 (FIG. 3C) with each threshold value generated by the threshold value generation unit 5 (FIG. 3D). Then, as shown in FIG. 3 (e), since the signal level change based on theft or the like is fast, the change in the threshold value cannot follow it, and the given data becomes larger than the threshold value. It is determined that an abnormality (theft) has occurred.

  On the other hand, in the case of a change in signal level due to a disturbance, as shown in the output of the amplifier 2 in FIG. 4A, the signal level changes slowly (peak P2 has a level increased due to the disturbance). Accordingly, the smoothing filter 3, the A / D converter 4 and the output are as shown in FIGS. 4B, 4C and 4D, respectively. As apparent from FIG. 4 (e), the change in the threshold can follow the change in the signal level, and the data D (n) acquired at any timing (n-th) exceeds the threshold Th (n). In other words, the peak “P2” is not erroneously detected as abnormal.

  Further, according to the present embodiment, as shown in FIGS. 5A and 5B, when the signal level in the normal state rises and falls due to the influence of disturbance caused by noise and the like, the thresholds Th1 and Th2 also rise and fall accordingly. Therefore, the detected signal (data amplified by the amplifier) does not exceed the threshold value regardless of the noise level. That is, for example, the threshold value Th1 set when the noise level is low as shown in FIG. 5A has changed (increased) as shown in FIG. 5B due to the influence of disturbance such as temperature change and rain. Then, the threshold value Th2 also increases accordingly. In either case, if the output of the sensor changes abruptly based on the theft or the like, the threshold value Th1 or Th2 is exceeded, so an abnormality can be detected.

  FIG. 6 shows a second embodiment of the present invention. As is clear from the comparison with FIG. 1, in this embodiment, the smoothing filter is removed from the structure of the first embodiment. For this reason, the signal input to the A / D converter 4 is a signal obtained by amplifying the output signal of the sensor 1 by the amplifier 2, and thus has a waveform that vibrates up and down as shown in FIG. Therefore, the threshold value generator 5 extracts the maximum value and the minimum value from the data digitized by the A / D converter 4 and stores the extracted data (a pair of the maximum value and the minimum value) in the temporary storage memory. In the following description, the maximum value is M and the minimum value is m. Depending on the sampling timing, there may be cases where the local maximum value and the local minimum value are not used. In this case, the data stored as the previous local maximum value and local minimum value are used as they are as the current local maximum value and local minimum value.

  Referring to FIG. 7 as an example, in the case of the sampling period as shown in FIG. 7A, the maximum values are M1 to M4, and the minimum values are m1 to m4. Therefore, at the timing of t (i-7), the immediately preceding pair of maximum value and minimum value is (M3, m2). Further, at the timing of t (i-5), since it is confirmed that the previous maximum value has been changed to M2, the pair of the maximum value and the minimum value becomes (M2, m2), and t (i− At the timing of 2), the pair of the maximum value and the minimum value immediately before becomes (M2, m1), and at the timing of t (i-1), whether or not M1 is a maximum value is unknown at this time, so The pair of maximum value and minimum value is (M2, m1), and the data level is lower than t (i-1) at the timing of t (i), so the value at t (i-1). M1 is known as the maximum value, and the pair of the maximum value and the minimum value is (M1, m2).

  In this way, if a local maximum or local minimum value can be detected, it is updated to that value, and when the local maximum or local minimum value has not been updated, the previous value is left, so that the local maximum and local minimum values remain. The pair updates the pair as new data. As a result, the past N data (maximum value and minimum value pairs) stored in the temporary storage memory of the threshold value generation unit 5 are as shown in FIG.

  Then, the threshold generation unit 5 calculates an average value for each of the maximum value and the minimum value, and raises a predetermined amount with respect to the calculated average value. Here, in this embodiment, the maximum value side is set to “positive” and the minimum value side is set to “negative”. Therefore, in the actual raising process, S is simply added to the average value of the maximum values, and the average of the minimum values is obtained. Simply subtract S from the value. Of course, in the present embodiment, instead of obtaining a simple average, as a processing method for performing a filtering process in a direction in which the change is gradual with N pieces of local maximum values and local minimum values, there are other methods such as IIR and FIR. The use of this method is not hindered. Also, the raising process is not limited to simply adding and subtracting S. Furthermore, the raising process on the maximum value side and the minimum value side is not necessarily the same.

If N = 4, the threshold on the local maximum side is
Maximum (positive) side threshold = ((M (i) + M (i−1) + M (i−2) + M (i−3)) / 4) + S
And the threshold on the local minimum side is
Minimum value (negative) side threshold = ((m (i) + m (i−1) + m (i−2) + m (i−3)) / 4) −S
It becomes.

  Then, in the comparison / determination unit 6, when the current data (D (n)) to be determined is on the local maximum side (referred to as “positive”), it is compared with the threshold based on the local maximum, and the local minimum In the case of the side (“negative”), it is compared with a threshold value based on the minimum value, and when each exceeds the threshold value, it is determined that there is an abnormality (theft or the like).

  Here, a specific example will be described. For example, assume that the output of the amplifier 2 is as shown in FIG. Peaks P3 and P3 ′ in FIG. 8A are waveforms based on the theft, and a sudden level change occurs. When the waveform data of the amplifier output is digitized (sampled) by the A / D converter 4 at a predetermined sampling period, it is as shown in FIG. At this time, assuming that the value of each data changes as displayed at the top of the horizontal axis, the maximum value M and the minimum value m stored in the temporary storage memory each time are written below each data. It becomes the value.

  Then, the threshold value generation unit 5 generates the local maximum value threshold value and the local minimum value threshold value based on the local maximum value and the local minimum value of N times (here, N = 4) including the current time. Based on the data in FIG. 8B, threshold data as shown in FIG. 9A is generated. Then, the comparison / determination unit 5 compares the output of the A / D converter 3 (FIG. 8B) with each threshold value generated by the threshold value generation unit 5. Then, as shown in FIG. 9B, the change in the signal level based on the theft or the like is fast, so the change in the threshold cannot follow it. In this example, either the maximum value or the minimum value Since the absolute value of the given data is larger than the threshold value, it is determined that an abnormality (theft) has occurred.

  On the other hand, in the case of a change in signal level due to a disturbance, as shown in the output of the amplifier 2 in FIG. 10A, the signal level changes slowly (peak P4 has a level increased due to the disturbance). Accordingly, the outputs of the A / D converter 4 and the threshold setting unit 5 are as shown in FIGS. 10B and 11A, respectively. As apparent from FIG. 11 (b), the change in the threshold can be changed to the change in the signal level, and the data D (n) acquired at any timing (n-th) is either the maximum value or the minimum value. The threshold value Th (n) is not exceeded and the peak “P4” is not erroneously detected as abnormal. Since other configurations and operational effects are the same as those of the first embodiment described above, detailed description thereof is omitted.

  12 and 13 show a third embodiment of the present invention. This embodiment is based on the first embodiment and is realized by an analog circuit. That is, the security device according to the present embodiment includes the sensor 1, the amplifier 2, the low-pass filter 7, the level shift circuit 8, and the comparison determination circuit 6 ′ in order from the signal input side. More specifically, the output of the amplifier 2 is given to the low pass filter 7 and the comparison judgment circuit 6 ′, and the output of the low pass filter 7 is given to the comparison judgment circuit 6 ′ via the level shift circuit 8. FIG. 12 is a block diagram showing the security device according to the present embodiment, and FIG. 13 shows an example of a specific circuit configuration.

  Considering the correspondence with the first embodiment, the low-pass filter 7 and the level shift circuit 8 have the same function as the threshold value generator 5 (the threshold value is changed and set following the change in the signal level). Has come to be realized.

  By filtering the sensor output amplified by the amplifier 2 with the low-pass filter 7, the high-frequency component is cut, so that not only the noise component but also the signal whose sensor output changes quickly based on theft or the like Components are also removed. Thereby, for example, it is assumed that the output of the amplifier 2 is as shown in FIG. 14A (the same as FIG. 3A). Here, the peak P1 in FIG. 14 is a waveform based on the theft, and a sudden level change occurs. The output of the low-pass filter 7 based on the signal of FIG. 14A is as shown in FIG. The peak P1 that has undergone a rapid level change cannot be followed by the low-pass filter 7 and is cut, and the level becomes smaller like P1 ′.

  Next, the level shift circuit 8 raises the output level of the low-pass filter 7 by a certain amount (this raising amount corresponds to S = 2 in the first embodiment), and FIG. As shown. The level shown in FIG. 14C is a threshold value at each timing, and is given to the comparison determination circuit 6.

  As a result, the comparison / determination circuit 6 compares the output signal of the amplifier 2 with the threshold set by the level shift circuit 8, so that the threshold (level shift) is applied at the peak P1, as shown in FIG. The output of the circuit 8) is exceeded and it can be determined that there is an abnormality.

  On the other hand, in the case of a change in signal level due to disturbance, as shown in the output of the amplifier 2 in FIG. 15A (same as FIG. 4A), the level changes slowly (peak P2 has a level due to disturbance). Rises). Therefore, the portion of the peak P2 can also pass through the low-pass filter 7, so that the output of the low-pass filter 7 is relatively such that the peak P2 'follows the peak P2 of the amplifier output as shown in FIG. In accordance with this, the output of the level shift circuit 8 is also as shown in FIG. Therefore, as apparent from FIG. 15D, the change in the threshold value can be made normal to the change in the signal level, and the level of the output signal of the amplifier obtained at any timing is output from the level shift circuit 8. The threshold value is not exceeded, and the peak “P2” is not erroneously detected as abnormal.

It is a figure explaining the conventional problem. It is a block diagram which shows 1st Embodiment of the security apparatus which concerns on this invention. It is a figure explaining an operation principle. It is a figure explaining an operation principle. It is a figure explaining an effect | action. It is a block diagram which shows 2nd Embodiment of the security apparatus which concerns on this invention. It is a figure explaining an operation principle. It is a figure explaining an operation principle. It is a figure explaining an operation principle. It is a figure explaining an operation principle. It is a figure explaining an operation principle. It is a block diagram which shows 3rd Embodiment of the security apparatus which concerns on this invention. It is a block diagram which shows 3rd Embodiment of the security apparatus which concerns on this invention. It is a figure explaining an operation principle. It is a figure explaining an operation principle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor 2 Amplifier 3 Smoothing filter 4 A / D converter 5 Threshold setting part 6 Comparison determination part 6 'Comparison determination circuit 7 Low pass filter 8 Level shift circuit

Claims (5)

A sensor,
A comparison determination unit that determines whether or not a value of a signal based on the output signal of the sensor exceeds a set threshold value, and determines that the abnormality is detected when the threshold value is exceeded;
A threshold setting means for setting the threshold for the comparison determination means;
The threshold setting means has a function of acquiring and temporarily storing a signal value based on an output signal of the sensor, and generating a threshold based on a plurality of recently stored data. apparatus.   The security device according to claim 1, wherein the plurality of latest data includes a value of a signal based on at least a sensor output signal acquired this time. Smoothing processing means, and A / D conversion means for A / D converting the output of the smoothing processing means,
The value of the signal based on the output signal of the sensor is smoothed by the smoothing processing means on the output signal or the signal processed into the output signal, and the smoothed signal is converted into the A / D signal. 3. The security device according to claim 1, wherein the security device has been converted into a digital value by a conversion means. A / D conversion means for A / D converting an output signal of the sensor or a signal processed into the output signal,
The threshold setting unit has a function of extracting a maximum value and a minimum value from a digital waveform signal given from the A / D conversion unit, and generating a threshold value based on the maximum value and a threshold value based on the minimum value, respectively. The security device according to claim 1, wherein:   The threshold setting means includes a low-pass filter that filters the output signal or an analog signal processed into the output signal, and a level shift means that shifts the output signal of the low-pass filter by a predetermined margin. The security device according to claim 1, wherein the security device is configured.

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