JP2018136279A - Detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detector which can detect objects existing in a wide range.SOLUTION: A detector includes: an output unit for outputting a first ultrasonic wave; a reception unit for receiving a reflection signal formed by reflection of the first ultrasonic wave by an object; a detection unit for detecting the object on the basis of the received reflection signal; a feedback signal processing unit for processing the received reflection signal and generating a feedback signal; and an ultrasonic wave generation unit for generating a first ultrasonic wave, the output unit outputting the feedback signal as a second ultrasonic wave and also outputting the first ultrasonic wave generated by the ultrasonic wave generation unit and the feedback signal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a detection device.

  2. Description of the Related Art Conventionally, human sensors such as IR sensors that detect human movement sense infrared rays emitted from the human body and detect temperature changes and infrared reflections. Such human sensors are used for applications such as automatic doors and flush toilets (see, for example, Patent Document 1).

In addition, the ultrasonic sensor uses ultrasonic waves with high directivity of about 40 kHz, so that the transmitted ultrasonic waves are reflected by the object and the distance from the object is measured from the time until the echo returns, It is used for applications such as non-destructive inspection for detecting defects such as piping from the waveform of the echo (see, for example, Patent Documents 2 and 3).
Patent Document 1 Japanese Patent Application Laid-Open No. 2006-017822 Patent Document 2 Japanese Patent Application Laid-Open No. 2009-265209 Patent Document 3 Japanese Patent Application Laid-Open No. 2015-161530

  In a conventional IR sensor, it has been difficult to detect a person when the ambient temperature around the sensor has increased to about the body temperature of the person. Further, in the ultrasonic sensor, when wide-angle detection is performed, ultrasonic distance attenuation is large, and it is difficult to detect an object at a distant position.

  In the first aspect of the present invention, the output unit that outputs the first ultrasonic wave, the reception unit that receives the reflected signal of the first ultrasonic wave reflected by the object, and the object based on the received reflected signal. A detection unit for detecting and a feedback signal processing unit for processing a received reflected signal to generate a feedback signal, and an output unit provides a detection device that outputs the feedback signal as a second ultrasonic wave.

  The above summary of the present invention does not enumerate all of the features of the present invention. A sub-combination of these feature groups can also be an invention.

The structural example of a detection apparatus is shown. The structural example of the detection part of a detection apparatus is shown. The time change of a reflected signal is shown. The time change of the output of a digital low pass filter is shown. The time change of the difference signal of the output of a digital low-pass filter is shown.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 shows a configuration example of a detection apparatus 100 in the present embodiment. The detection apparatus 100 outputs an ultrasonic wave, receives a reflected signal reflected by an object 160 such as a person, and detects the moving object 160 based on the reflected signal. The detection apparatus 100 includes an ultrasonic generation unit 110, an output unit 120, a reception unit 130, a feedback signal processing unit 140, and a detection unit 150.

  The ultrasonic generator 110 generates the first ultrasonic wave output from the output unit 120. The ultrasonic generation unit 110 includes a signal generation unit 111, a signal amplification unit 112, a first DA conversion unit 113, a first filter unit 114, and a first power amplifier 115.

  The signal generator 111 may be a digital circuit such as a DSP (Digital Signal Processor), for example, and generates a digital signal having a predetermined frequency. The signal amplification unit 112 is connected to the signal generation unit 111 and amplifies the generated digital signal. The first DA converter 113 is connected to the signal amplifier 112 and converts the digital signal from the signal amplifier 112 into an analog signal. The first filter unit 114 is connected to the first DA conversion unit 113, and removes harmonics generated by aliasing during digital-analog conversion from the analog signal. The first filter unit 114 is, for example, an image removal filter. The first power amplifier 115 is connected to the first filter unit 114 and the output unit 120, amplifies the signal from the first filter unit 114, and transmits the amplified signal to the output unit 120.

  The output unit 120 outputs a signal from the ultrasonic wave generation unit 110 as a first ultrasonic wave, and outputs a feedback signal from the feedback signal processing unit 140 as a second ultrasonic wave. The output unit 120 includes a first speaker 121 and a second speaker 122.

  The first speaker 121 and the second speaker 122 may output signals through different channels. The first speaker 121 is connected to the ultrasonic generator 110 and outputs the first ultrasonic wave from the ultrasonic generator 110. The second speaker 122 is connected to the feedback signal processing unit 140 and outputs the feedback signal from the feedback signal processing unit 140 as the second ultrasonic wave.

  The receiving unit 130 receives a reflected signal in which the first ultrasonic wave and the second ultrasonic wave output from the output unit 120 are reflected by the object 160, and performs processing on the reflected signal. The reception unit 130 includes a microphone 131, a microphone amplifier 132, an AD conversion unit 133, a second filter unit 134, and a reflected signal amplification unit 135.

  The microphone 131 is connected to the microphone amplifier 132, converts a reflected wave from the object 160 into a reflected signal, and transmits the reflected signal to the microphone amplifier 132. The microphone amplifier 132 is connected to the AD conversion unit 133, amplifies the reflected signal, and transmits the amplified signal to the AD conversion unit 133. The AD conversion unit 133 is connected to the second filter unit 134, converts an analog reflected signal into a digital signal, and transmits the digital signal to the second filter unit 134. The second filter unit 134 is connected to the reflected signal amplifying unit 135 and filters the reflected signal from the AD converting unit 133 so that only a specific frequency band is obtained. For example, the second filter unit 134 is a digital bandpass filter. The reflected signal amplification unit 135 is connected to the feedback signal processing unit 140 and the detection unit 150 and amplifies the reflected signal from the second filter unit 134. The reflected signal amplifier 135 is a digital circuit, for example.

  The feedback signal processing unit 140 processes the reflected signal from the receiving unit 130 to generate a feedback signal. The feedback signal processing unit 140 includes a second DA conversion unit 141, a third filter unit 142, and a second power amplifier 143.

  The second DA conversion unit 141 is connected to the reception unit 130 and the third filter unit 142, converts the digital reflected signal from the reception unit 130 into an analog signal, and transmits the analog signal to the third filter unit 142. The third filter unit 142 is connected to the second power amplifier 143, filters the signal from the second DA converter 141 to remove harmonics, and transmits the filtered signal to the second power amplifier 143. The third filter unit 142 is, for example, an image removal filter. The second power amplifier 143 is connected to the output unit 120, amplifies the signal from the third filter unit 142, generates a feedback signal, and transmits the feedback signal to the output unit 120.

  The detection unit 150 detects the object 160 based on the reflected signal received by the reception unit 130. The detection unit 150 includes a detection unit 151, an addition unit 152, a signal level comparison unit 153, and a threshold setting unit 154.

  The detection unit 151 is connected to the reception unit 130 and the addition unit 152, and outputs a signal Hi and a signal Lo to the addition unit 152 in accordance with a signal from the reception unit 130. Adder 152 is connected to signal level comparator 153 and transmits a difference signal indicating the difference between signal Hi and signal Lo from detector 151 to signal level comparator 153. The threshold setting unit 154 is connected to the signal level comparison unit 153 and outputs a preset threshold value to the signal level comparison unit 153. The signal level comparison unit 153 outputs a detection signal based on the difference signal from the addition unit 152 and the threshold value from the threshold setting unit 154.

  Here, the detection unit 151 will be described in detail with reference to FIG. FIG. 2 shows a configuration example of the detection unit 151. The detection unit 151 includes a digital low-pass filter 200 having a faster time constant and a digital low-pass filter 210 having a slower time constant. The digital low-pass filter 200 having a faster time constant and the digital low-pass filter 210 having a slower time constant need only have different time constants. The digital low-pass filter 210 having a slower time constant may be a digital low-pass filter having a faster time constant. The time constant is larger than that of the filter 200.

  The digital low-pass filter 200 having a faster time constant performs low-pass filtering on the reflected signal, and outputs a signal Hi that changes rapidly following the change of the input reflected signal. The digital low-pass filter 200 with a faster time constant includes a first detection amplification unit 201, a first flip-flop 202, a second detection amplification unit 203, and a first detection addition unit 204.

  The first detection amplification unit 201 amplifies the reflected signal from the reception unit 130 and transmits the amplified signal to the first detection addition unit 204. For example, the first detection amplification unit 201 multiplies the reflected signal by a coefficient 1-a (where 0 <a <1). The first flip-flop 202 is connected to the first detection / addition unit 204 and the second detection / amplification unit 203, and delays the signal Hi from the first detection / addition unit 204 to generate a second detection / amplification unit. 203. The second detection amplification unit 203 amplifies the delayed signal from the first flip-flop 202 and transmits the amplified signal to the first detection addition unit 204. For example, the second detection amplification unit 203 multiplies the delayed signal by a coefficient a. The first detection / addition unit 204 adds the signal from the first detection / amplification unit 201 and the signal from the second detection / amplification unit 203, and adds the signal Hi to the first flip-flop 202 and the addition unit 152. And send to.

  The digital low-pass filter 210 having a slower time constant performs low-pass filtering on the reflected signal, and outputs a signal Lo that changes slowly following the change of the input reflected signal. The digital low-pass filter 210 having a slower time constant includes a third detection amplification unit 211, a second flip-flop 212, a fourth detection amplification unit 213, and a second detection addition unit 214.

  The third detection amplification unit 211 amplifies the reflected signal from the reception unit 130 and transmits the amplified signal to the second detection addition unit 214. For example, the third detection amplification unit 211 multiplies the reflected signal by a coefficient 1-b (where 0 <b <1). The second flip-flop 212 is connected to the second detection / addition unit 214 and the fourth detection / amplification unit 213, and delays the signal Lo from the second detection / addition unit 214 to generate a fourth detection / amplification unit. To 213. The fourth detection amplification unit 213 amplifies the delayed signal from the second flip-flop 212 and transmits the amplified signal to the second detection addition unit 214. For example, the fourth detection amplification unit 213 multiplies the delayed signal by a coefficient b. The second detection / addition unit 214 adds the signal from the third detection / amplification unit 211 and the signal from the fourth detection / amplification unit 213, and adds the signal Lo to the second flip-flop 212 and the addition unit 152. And send to.

  Next, operation | movement of the detection apparatus 100 in this embodiment is demonstrated. The signal generator 111 of the ultrasonic generator 110 discretely generates a sine wave signal in a non-audible sound band having a frequency of 18 kHz to 40 kHz, preferably 18 kHz to 30 kHz. The ultrasonic generation unit 110 performs signal processing on the generated signal and transmits the signal to the output unit 120.

  The output unit 120 outputs the signal from the ultrasonic wave generation unit 110 from the first speaker 121 of the right channel Rch as a first ultrasonic wave having a frequency of 18 kHz to 40 kHz, preferably 18 kHz to 30 kHz. With an ultrasonic wave having such a frequency, a wider-angle object can be detected.

  The receiving unit 130 receives the reflected signal reflected by the object 160, converts it to an analog signal, amplifies the analog signal, and transmits the amplified analog signal to the detection unit 150 and the feedback signal processing unit 140. For example, the second filter unit 134 of the receiving unit 130 performs filtering for removing sharply other than the frequency component of the frequency band including the frequency of the first ultrasonic wave from the reflected signal, preferably the first super-band. Filtering is performed to sharply remove components other than the same frequency component as the sound wave frequency. Specifically, the second filter unit 134 converts the reflected signal into a signal having a frequency of 18 kHz to 40 kHz, preferably 18 kHz to 30 kHz, by filtering.

  The feedback signal processing unit 140 performs signal processing on the reflected signal from the reception unit 130 to generate a feedback signal, and transmits the feedback signal to the output unit 120.

  The output unit 120 outputs the feedback signal from the feedback signal processing unit 140 from the second speaker 122 of the left channel Lch as a second ultrasonic wave having a frequency of 18 kHz to 40 kHz, preferably 18 kHz to 30 kHz. The output unit 120 outputs the first ultrasonic wave from the ultrasonic wave generation unit 110 through a different channel while outputting the feedback signal. Note that the output unit 120 may output the first ultrasonic wave from the second speaker 122 of the left channel Lch and output the feedback signal from the first speaker 121 of the right channel Rch.

  As described above, the detection apparatus 100 generates a feedback signal from the reflected signal received by the receiving unit 130, outputs the feedback signal from the output unit 120, and receives the reflected signal of the feedback signal by the receiving unit 130, thereby receiving the receiving unit 130, A feedback loop including a feedback signal processing unit 140 and an output unit 120 is formed. The ultrasonic wave output from the output unit 120 is attenuated by the spatial loss until it is reflected by the object 160 and reaches the receiving unit 130, and then amplified by the reflected signal amplification unit 135 of the receiving unit 130. Is output. As a result, the reflected signal received by the receiving unit 130 is the square of the reflected signal obtained by reflecting the first ultrasonic wave from the ultrasonic generating unit 110 on the object 160 and the reflected signal obtained by reflecting the feedback signal on the object 160. The sum square. Since the reflected signal amplified by the square sum square is output from the output unit 120 again, the reflected signal received by the receiving unit 130 is further increased, and the detection apparatus 100 is highly sensitive and greatly improves the detection range. To do.

  Here, it is preferable that the reflected signal amplifying unit 135 of the receiving unit 130 amplifies the reflected signal so that the amplitude of the feedback signal output from the output unit 120 does not increase with time. For example, the gain of the reflected signal amplification unit 135 of the reception unit 130 is set to the highest value in a range where the feedback gain of the feedback loop including the spatial loss is 0 dB or less. Thereby, the detection apparatus 100 can amplify a feedback signal effectively in the range which does not generate howling.

  The detection unit 150 receives a reflection signal obtained by reflecting the first ultrasonic wave and the feedback signal from the object 160 from the reception unit 130, and outputs a detection signal corresponding to the change in the reflection signal. The detection of the change in the reflected signal by the detection unit 150 will be described with reference to FIGS. FIG. 3 shows the time change of the reflected signal. FIG. 4 shows changes with time in the outputs of the digital low-pass filters 200 and 210. FIG. 5 shows a time change of the differential signal output from the digital low-pass filters 200 and 210.

  As shown in FIG. 3, the reflected signal received by the receiving unit 130 changes when the object 160 moves, for example. At this time, as shown in FIG. 4, the output signal Hi of the digital low-pass filter 200 having a faster time constant of the detection unit 150 immediately follows the change of the reflected signal. On the other hand, the output signal Lo of the digital low-pass filter 210 having a slower time constant gradually changes following the change of the reflected signal. Therefore, the difference between the signals Hi and Lo is large at the moment when the reflected signal changes, but the difference between the signals Hi and Lo decreases after a certain period of time without the reflected signal changing thereafter. For this reason, the adder 152 to which the signals Hi and Lo are input outputs a differential signal reflecting the change in the reflected signal as shown in FIG.

  The signal level comparison unit 153 compares the difference signal A output from the addition unit 152 with a predetermined threshold B from the threshold setting unit 154, and outputs a detection signal according to the comparison result. For example, when the difference signal A is larger than the threshold value B, the signal level comparison unit 153 outputs a detection signal indicating that the object 160 has been detected.

  The detection apparatus 100 of the present embodiment can detect a wide range of objects by increasing the sensitivity by a feedback loop even when detecting a wide angle by lowering the frequency. Therefore, the detection apparatus 100 can detect an object by a reflection signal from the back surface of the detection apparatus 100. For example, the entire room can be covered by the single detection apparatus 100 and the object 160 can be monitored. In addition, the detection device 100 can be used for the purpose of grasping the presence of a person, opening / closing of a door or window, usage status of a conference room, etc., and also for security applications for detecting room abnormalities such as entering a room. Is possible. Moreover, since the detection apparatus 100 can use a normal speaker and microphone that output ultrasonic waves of a low frequency, a system that already includes the speaker and microphone, for example, a voice recognition device such as an interphone or a robot. Easily adaptable to.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 100 Detection apparatus, 110 Ultrasonic wave generation part, 111 Signal generation part, 112 Signal amplification part, 113 1st DA converter part, 114 1st filter part, 115 1st power amplifier, 120 output part, 121 1st 1st Speaker, 122 Second speaker, 130 Receiver, 131 Microphone, 132 Microphone amplifier, 133 AD converter, 134 Second filter, 135 Reflected signal amplifier, 140 Feedback signal processor, 141 Second DA converter 142, third filter unit, 143 second power amplifier, 150 detection unit, 151 detection unit, 152 addition unit, 153 signal level comparison unit, 154 threshold setting unit, 160 object, 200 digital constant low-pass filter with faster time constant 201 First detection amplification unit 202 First flip-flop 203 2 detection amplifying unit, 204 first detection adding unit, 210 digital low-pass filter having a slower time constant, 211 third detection amplifying unit, 212 second flip-flop, 213 fourth detection amplifying unit, 214 second Detection adder

Claims (7)

An output unit for outputting a first ultrasonic wave;
A receiver that receives a reflected signal of the first ultrasonic wave reflected by an object;
A detector that detects the object based on the received reflected signal;
A feedback signal processing unit that processes the received reflected signal to generate a feedback signal;
With
The output unit outputs the feedback signal as a second ultrasonic wave. An ultrasonic generator for generating the first ultrasonic wave;
The detection device according to claim 1, wherein the output unit outputs the first ultrasonic wave generated by the ultrasonic wave generation unit and the feedback signal. The detection device according to claim 2, wherein the output unit outputs the first ultrasonic wave generated by the ultrasonic wave generation unit and the feedback signal through different channels. The reception unit includes a reflection signal amplification unit that amplifies the reflection signal,
The detection apparatus according to any one of claims 1 to 3, wherein the reflected signal amplification unit amplifies the reflected signal so that an amplitude of the feedback signal output from the output unit does not increase with time. The detection device according to claim 1, wherein the output unit outputs the first ultrasonic wave having a frequency of 18 kHz or more and 40 kHz or less. The detection device according to claim 1, wherein the detection unit detects the object based on a change in the reflected signal. The detector is
A digital low-pass filter with a faster time constant to which the reflected signal is input;
A digital low-pass filter having a slower time constant to which the reflected signal is input;
A comparison unit that compares a difference between an output of the digital low-pass filter with a faster time constant and an output of the digital low-pass filter with a slower time constant with a threshold;
The detection device according to claim 6.

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