JPS6218026B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ultrasonic moving object detection device. Conventionally, in this type of Doppler-type ultrasonic moving object detection device, ultrasonic pulses are sent into free space intermittently at intervals of time, and the reflected waves from free space that arrive within a set time are detected as FM. Detect,
Next, only level detection or pulse width discrimination was performed, so if the transmission time width of the ultrasonic pulse was shortened, there was a problem that reflections from stationary objects such as plants could be mistaken for reflections from a moving human body. Ta. There was also a risk that reflections from rain could be mistaken for reflections from a moving human body. The present invention seeks to provide an ultrasonic moving object detection device that eliminates the above-mentioned drawbacks. The ultrasonic moving object detection device of the present invention will be explained below with reference to the drawings. In FIGS. 1 and 2, reference numeral 1 denotes a periodic oscillation circuit that generates a trigger pulse at every desired time that can be selected as appropriate. Reference numeral 2 denotes a detection distance setting circuit connected to the output end of the periodic oscillation circuit 1, which adjusts the pulse width of the output rectangular wave of the monostable multivibrator that operates in response to the arrival of the trigger pulse appropriately according to the desired detection distance. Adjust. Reference numeral 3 denotes an ultrasonic signal transmission time width setting circuit connected to the output end of the detection distance setting circuit 2, which outputs a rectangular pulse of a predetermined width in response to arrival of the output rectangular wave of the detection distance setting circuit 2. 4 is a first AND gate whose one input terminal is connected to the output terminal of the transmission time width setting circuit 2;
The other input terminal is connected to the output terminal of the oscillation circuit 5, and allows the output wave of the oscillation circuit 5 to pass during the high level period of the rectangular pulse output from the transmission time width setting circuit 3. 6 is a first amplifier circuit for transmitting waves connected to the first AND gate 4;
The output of the first AND gate 4 is amplified and given to the ultrasonic transducer 7 for subsequent wave transmission. Reference numeral 8 denotes a receiving ultrasonic transducer disposed near the transmitting ultrasonic transducer 7, which detects stationary objects and moving objects transmitted from the transmitting ultrasonic transducer 7 and within the detection area. The ultrasonic wave reflected by the waveguide is received and applied to a second amplification circuit 9 for subsequent wave reception connected to the output end. Reference numeral 10 denotes a pulse shaping circuit inserted between the second amplifier circuit 9 and the periodic oscillation circuit 1, which converts the received signal suitably amplified by the second amplifier circuit 9 into AM.
It detects the waves and sends out an output according to the received signal, and when the level of the received signal reaches a predetermined level or higher, the output is appropriately set to a high level. 11
is a second AND gate whose one input terminal is connected to the output terminal of the pulse shaping circuit 10, and whose other input terminal is connected to the output terminal of the detection distance setting circuit 2; The output of the pulse shaping circuit 10 is passed only in accordance with the high level period of the output rectangular wave of No. 2. 12 is a signal switching circuit whose first and second input terminals are respectively connected to the output terminal of the oscillation circuit 5 and the output terminal of the second AND gate 11, and the output of the second AND gate 11 is at a low level. The second amplifier circuit 9 allows the output wave of the oscillation circuit 5 to pass through during the period, and is converted into a rectangular wave by the first level detection circuit 13 during the period when the output of the second AND gate 11 is at a high level. Let the output of pass through. 14 is an FM detection circuit connected to the output end of the signal switching circuit 12, which detects the output of the second amplifier circuit 9 and outputs a voltage proportional to the frequency. A second level detection circuit 15 is connected to the output terminal of the FM detection circuit 14 via a third amplifier circuit 16, and outputs a high-level rectangular wave to the first output terminal only during a period when a predetermined value is exceeded. A high-level rectangular wave is output from the second output terminal only during a period in which the voltage is lower than another predetermined value. Reference numeral 17 denotes a NOR gate whose two input terminals are connected to the first and second output terminals of the second level detection circuit 15, respectively, and whose output terminal is connected to the first pulse width detection circuit 18. 1
A third level detection circuit 9 is inserted between the FM detection circuit 14 and the first pulse width detection circuit 18, and a bandpass filter 20 and a fourth amplifier circuit are inserted between the FM detection circuit 14 and the first pulse width detection circuit 18. A series circuit with 21 is inserted. 22 has a set input terminal connected to the first
A flip-flop is connected to the pulse width detection circuit 18, and the reset input terminal is connected to the NOR gate 17.
It is connected to the. A first NAND gate 23 has one input terminal connected to the flip-flop 22, and the other input terminal is connected to one output terminal of the second level detection circuit 15 via a second pulse width detection circuit 24. It is connected. 25 is a second flip-flop whose one input terminal is connected to the flip-flop 22;
is a NAND gate whose other input terminal is connected to the other output terminal of the second level detection circuit 15 via the third pulse width detection circuit 26. Reference numeral 27 denotes an output circuit connected to the first and second NAND gates 23 and 25 via first and second drive circuits 28 and 29, respectively. Drives alarm circuits, etc. IC1 is a first operational amplifier circuit included in the third amplifier circuit 16;
It is connected to the output end of the FM detection circuit 14, and only passes and amplifies low frequency components. IC2 and IC3 are second level detection circuits included in the second level detection circuit 15;
In the third operational amplifier circuit, a non-inverting input terminal and an inverting input terminal are connected to the output terminal of the first operational amplifier circuit IC1, and the output terminal is connected to the input terminal of the NOR gate 17. IC4 is a fourth operational amplifier circuit included in the bandpass filter 20 and the fourth amplifier circuit 21, and the non-inverting input terminal is connected to the second capacitor C2 that blocks the DC component.
It is connected to the output end of the FM detection circuit 14, and only passes and amplifies high frequency components. IC5 and IC6 are the fifth level detection circuit included in the third level detection circuit 19;
A sixth operational amplifier circuit has an inverting input terminal and a non-inverting input terminal connected to the output terminal of the fourth operational amplifier circuit IC4. T _r is a transistor of the first pulse width detection circuit 18;
The output terminals of the operational amplifier circuits IC5 and IC6 are grounded via the inverter INV, and the bases are connected to the output terminal of the NOR gate 17 via the first resistor R1. C3 is a third capacitor of the first pulse width detection circuit 18, which is connected in parallel to the transistor T _r , and the connection point with the transistor T _r is connected to a constant voltage source via a second resistor R2. Connected to _Vcc . G1 and G2 are NOR gates constituting the flip-flop 22, one input terminal of which is connected to the connection point between the transistor T _r and the capacitor C3 and the output terminal of the NOR gate 17, and the other input terminal of each of them is It is connected to the output terminals of the other NOR gates G1 and G2. D1 is the first diode of the second pulse width detection circuit 24, the cathode of which is connected to the output terminal of the second operational amplifier circuit IC2, the anode of which is grounded via the fourth capacitor C4, and the third It is connected to a constant voltage source _Vcc via a resistor R3. D2 is a second diode of the third pulse width detection circuit 26, whose cathode is connected to the output terminal of the third operational amplifier circuit IC3, and whose anode is grounded via the fifth capacitor C5. It is connected to a constant voltage source _Vcc via a resistor R4. The above is the configuration of the embodiment, and the matters described in the claims correspond as follows. In other words, the "transmission system that intermittently transmits ultrasonic waves with a predetermined time width into space" includes a periodic oscillation circuit 1, a detection distance setting circuit 2, a transmission time width setting circuit 3, an oscillation circuit 5, and a first The AND gate 4, the first amplification circuit 6, and the ultrasonic transducer 7 correspond. "Receiving system that receives reflected waves from the space"
includes an ultrasonic transducer 8, a second amplifier circuit 9, and a first
level detection circuit 13, pulse shaping circuit 10,
The second AND gate 11 and signal switching circuit 12 correspond. The FM detection circuit 14 corresponds to the "FM detection circuit for FM detecting the received signal". A third amplifier circuit is used in the "stationary object reflection separation unit that detects when the existence time width of a signal exceeding a predetermined level, which is a low frequency component signal included in the output of this FM detection circuit, exceeds a predetermined value." 16, a second level detection circuit 15, a second pulse width detection circuit 24, and a third pulse width detection circuit 26. A bandpass filter 20 is included in the "rain reflection separation unit that detects when the non-existence time width of a signal of a high frequency component included in the output of the FM detection circuit and which exceeds a predetermined level exceeds a predetermined value." 4 amplifier circuit 21, third level detection circuit 1
9, a NOR gate 17, a first pulse width detection circuit 18, and a flip-flop 22. The "gate section that operates the output circuit by calculating the logical product of the detection output of the stationary object reflection separation section and the detection output of the rain reflection separation section" includes a first NAND gate 23, a second NAND gate 25, a first The drive circuit 28 and the second drive circuit 29 correspond to the drive circuit 28 and the second drive circuit 29. Note that the output circuit 27 corresponds to the "output circuit". It is. The operation of the ultrasonic moving object detection device of the present invention will now be described in detail. In response to the trigger pulse of the periodic oscillation circuit 1, the detection distance setting circuit 2 outputs a rectangular wave having an appropriate pulse width. In response to the rectangular wave output from the detection distance setting circuit 2, the transmission time width setting circuit 3 outputs a rectangular pulse having an ultrasonic wave transmission time of at least about 4.0 mSec. The first AND gate 4 allows the output wave of the oscillation circuit 5, for example, the output wave of 40KHZ, to pass through during the period when the rectangular pulse is input, and the first
The signal is applied to an ultrasonic transducer 7 for wave transmission via an amplifier circuit 6 . Ultrasonic transducer 7 is at least about 4.0mSec
It is driven by the output wave of the oscillation circuit 5 over a period of , and sends out ultrasonic waves into free space. The transmitted ultrasonic waves are reflected by stationary objects such as plants or moving objects such as rain or a human body existing in free space, and reach the ultrasonic transducer 8 for wave reception. The reflected wave signal received by the ultrasonic transducer 8 is reflected by a moving human body at A in Figure 3a, a stationary object such as a plant by B in Figure 3A, and a rain by 11 in Figure 3A. The signal is amplified by the second amplifier circuit 9 and provided to the pulse shaping circuit 10 and the first level detection circuit 13. The pulse shaping circuit 10 outputs a high level signal when the amplitude of the output of the second amplifier circuit 9 exceeds a predetermined level, and supplies it to the periodic oscillation circuit 1 to shorten the interval between trigger pulses. Pulse shaping circuit 10
The output is also given to the second AND gate 11, and is passed through when the output of the detection distance setting circuit 2 is at a high level and is given to the subsequent signal switching circuit 12. The first level detection circuit 13 provides the output signal switching circuit 12 with an output that becomes high level when the output of the second amplifier circuit 9 is equal to or higher than a predetermined level. The signal switching circuit 12 allows the output of the first level detection circuit 13 to pass when the signal applied from the second AND gate 11 is at a high level, and allows the output of the oscillation circuit 5 to pass when the signal is at a low level. The output of the oscillation circuit 5 and the output of the first level detection circuit 13, which are passed through the signal switching circuit 10, are sent to the FM detection circuit 1.
4, the frequency is detected and the frequency is converted into a proportional voltage. The output of the FM detection circuit 14 is
Figure 3 b and b are for A in figure a, i.e. a moving human body, B in figure 3 a is in front of a stationary object such as plants, B and B in figure 3, and C in figure 3 a is for rain. Figure 3b,
C, and is applied to the third amplifier circuit 16. In the third amplifier circuit 16, the output of the FM detection circuit 14 is received via a capacitor C1 that blocks direct current components, and is amplified by an operational amplifier circuit IC1 that passes and amplifies only low frequency components. Operational amplifier circuit IC1
The output is given to the second level detection circuit 15 as the output of the third amplifier circuit 16. In the second level detection circuit 15, the output of the operational amplifier circuit IC1 is applied to the non-inverting input terminal of the operational amplifier circuit IC2 and the inverting input terminal of the operational amplifier circuit IC3. The output shown in Fig. 3C, which amplifies the positive side component exceeding the set level, appears at the output terminal of the operational amplifier circuit IC3, and the output shown in Fig. 3D, which amplifies the negative side component below the set level, appears at the output terminal of the operational amplifier circuit IC3. . A, B, and C in FIGS. 3C and 3D correspond to A, B, and C in FIGS. 3A and B, respectively, that is, reflections from stationary objects such as moving human plants and rain. Further, the output of the FM detection circuit 14 is given to a fourth amplifier circuit 21 via a bandpass filter 20. Bandpass filter 20 and fourth amplifier circuit 2
1, a capacitor C that blocks the DC component
2 receives the output of the FM detection circuit 14,
It is amplified by an operational amplifier circuit IC4 that passes and amplifies only high frequency components, for example, about 1KHZ to about 4KHZ. An output as shown in FIG. 3e appears at the output terminal of the operational amplifier circuit IC4. A, B, and C in FIG. 3E correspond to A, B, and C in FIGS. 3A to 3D, respectively, that is, reflections from a moving human body, stationary objects such as plants, and rain. The output of the operational amplifier circuit IC4 is given to the third level detection circuit 19 as the output of the fourth amplifier circuit 21. In the third level detection circuit 19, the inverting input terminal of the operational amplifier circuit IC5 and the non-inverting input terminal of the operational amplifier circuit IC6 are connected to the operational amplifier circuit IC4.
, that is, the output shown in FIG. 3e, the output terminal of the operational amplifier circuit IC5 that amplifies the negative side component below the set level and the operational amplifier circuit that amplifies the positive side component that exceeds the set level. An output appears at the output terminal of the third level detection circuit 19 connected to the output terminal of the IC 6 as shown in FIG. 3f. That is, a rectangular wave having a time width corresponding to the time when a high frequency component exceeding the set level exists in the output of the FM detection circuit 14 appears at the output end of the third level detection circuit 19. A, B, and C in Figure 3 f are
They correspond to A, B, and C in FIG. 3 a to e, respectively. The two outputs of the second level detection circuit 15, that is, the outputs of the operational amplifier circuits IC2 and IC3, are connected to the NOR gate 1.
7 to the first pulse width detection circuit 18. The input terminal of the first pulse width detection circuit 18 is
It is also connected to the output terminal of the third level detection circuit 19 via an inverter INV. That is, the base of the transistor T _r which grounds the output terminal of the third level detection circuit 19 via the inverter INV is connected to the resistor R.
1 to the output terminal of the NOR gate 17. As a result, the output of the NOR gate 17 becomes low level only when the outputs of the operational amplifier circuits IC2 and IC3 shown in FIG. 3c and d are at a high level, and the transistor T _r becomes non-conducting. An inverted signal of the output of the third level detection circuit 19 is applied to an integrating circuit formed by a resistor R2 and a capacitor C3. In other words, only when the output of the FM detection circuit 14 contains at least a low frequency component, the first pulse width detection circuit outputs an integral output corresponding to a time width in which no high frequency component of the output of the FM detection circuit 14 is present. 18 outputs. At the output terminal of the integrating circuit of the resistor R2 and the capacitor C3, outputs as shown in FIG. 3g, a, b, and c appear corresponding to a, b, and c of FIG. At the output terminal of the flip-flop 22, which uses the output of the first pulse width detection circuit 18 as a set input and the output of the NOR gate 17 as a reset input, a third Outputs such as A, B, and C in Figure b appear. That is, when the output of the FM detection circuit 14 contains a low frequency component and the high frequency component does not exist continuously for a predetermined period of time, the level becomes high, and the FM detection circuit 1
When the output of the flip-flop 4 does not contain a low frequency component, the flip-flop 22 outputs a low level output. One output of the second level detection circuit 15, that is, the output of the operational amplifier circuit IC2 shown in FIG. , for the high levels of c, a, b, and c in figure 3, the integral outputs shown in a, b, and c in figure 3 i are the second
It is output as the output of the pulse width detection circuit 24. That is, the second pulse width detection circuit 24
An integrated output corresponding to the time when the low frequency component of the output of the detection circuit 14 exceeds a set level on the positive side is sent out. Further, the other output of the second level detection circuit 15, that is, the output of the operational amplifier circuit IC3 shown in FIG.
and capacitor C5, so that the integral outputs as shown in A, B, and C in FIG. 3J correspond to the high levels in FIG. It is output as the output of the pulse width detection circuit 26 of No. 3. That is, the third pulse width detection circuit 26 sends out an integral output corresponding to the time when the low frequency component of the output of the FM detection circuit 14 becomes less than the set level on the negative side. One input terminal of the first NAND gate 23 is given the output of the flip-flop 22 shown in A, B, and C of FIG. 3h, and the other input terminal is given the output of the flip-flop 22 shown in Since the outputs of the second pulse width detection circuit 24 shown in , c are given, outputs as shown in k, a, b, and c of FIG. 3 appear. In other words, the first NAND gate 23 is activated only when the continuous existence time of the positive side low frequency component of the output of the FM detection circuit 14 becomes a predetermined value or more, and the continuous existence time of the high frequency component becomes a predetermined value or more. output will be at a low level. One input terminal of the second NAND gate 25 is provided with the outputs of the flip-flop 22 shown in A, B, and C in FIG. 3H, and the other input terminal is provided with the outputs A, B, and R in FIG. Since the outputs of the third pulse width detection circuit 26 shown in , C are given, the outputs as shown in FIG. That is, only when the continuous existence time of the negative side low frequency component of the output of the FM detection circuit 14 becomes a predetermined value or more, and the continuous absence time of the high frequency component becomes a predetermined value or more, the second NAND gate is activated. The output of 25 will be at a low level. The outputs of the first and second NAND gates 23 and 25 shown in FIGS. 3k and 3l are applied to first and second drive circuits 28 and 29, respectively. In the first and second drive circuits 28 and 29, when a low level signal of a predetermined width is input during the detection period, the subsequent output circuit 27
operate. There is a shift between the time width T1 set in the transmission time width setting circuit 3 and the average value E, standard deviation a, and 90% confidence limit of the time width T2 from the rise to fall of the output of the FM detection circuit 14. The following experimental results have been obtained for the human body.

[Table] Therefore, it is clear that the time width of the output of the FM detection circuit 14 for a moving human body changes in proportion to the time width set by the transmission time width setting circuit 3. In addition, the following experimental results have been obtained for stationary objects such as plants.

[Table] Therefore, the time width of the output of the FM detection circuit 14 for stationary objects such as plants is determined by the output time width setting circuit 3.
Even if you change the set time width, there is almost no change, the average value is about 0.8 to about 0.9 mSec, and (average value + 3a)
It is clear that the current time remains below about 2.8 mSec. Furthermore, regarding a moving human body and rain, there is a relationship as shown in FIG. 4 between the fluctuation in the voltage level of the output of the FM detection circuit 14 and the fluctuation width, that is, the fluctuation period. Therefore, the output of the FM detection circuit 14 for a moving human body is the same as the output of the FM detection circuit 14 for a moving human body.
It is clear that there is a significant difference in voltage level fluctuation and fluctuation period between the output of Based on the above experimental results, in the ultrasonic moving object device of the present invention, the set time width of the transmission time width setting circuit 3 is set to approximately 4.0 mSec or more, and the time of the output of the FM detection circuit 14 for stationary objects such as plants is set. For the value of adding 3a to the average width, that is, about 2.8mSec,
A 90% confidence limit value of the time width of the output of the FM detection circuit 14 for a moving human body, that is, approximately 3.2 mSec, is obtained to separate reflections from a moving human body and reflections from stationary objects such as plants. In addition, in the ultrasonic moving object detection device of the present invention, the output of the FM detection circuit 14 is passed through a series circuit of a bandpass filter 20, an amplifier circuit 21, and a level detection circuit 19 to detect high-frequency waves contained in reflected waves from rain. The components are separated along the broken line in FIG. 4, and if this separated signal does not exist for a predetermined period or longer and a low frequency component is present, it is determined that it is not a reflection of rain. As is clear from the above, the ultrasonic moving object detection device of the present invention can detect (a) a moving human body by continuously sending out ultrasonic pulses into free space over a time width of about 4.0 mSec or more; It is possible to separate reflections from stationary objects such as plants and trees, and extract only reflections from a moving human body.In addition, it is possible to separate high-frequency components of the FM detection output of ultrasonic pulses reflected from free space. In addition, by detecting the level, (b) the presence of reflections from rain can be detected and separated from reflections from a moving human body. In other words, (c) the transmission time width of the ultrasonic pulse can be sufficiently shortened, and The reflection caused by the human body can be separated from the reflection caused by other objects, and (d) remarkable effects such as a significant reduction in maintenance costs can be realized.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the ultrasonic moving object detection device of the present invention, FIG. 2 shows a detailed view of the same part, and FIGS. 3 a to 1 and 4 show explanatory diagrams of the same operation. DESCRIPTION OF SYMBOLS 1... Periodic oscillation circuit, 2... Detection distance setting circuit, 3... Sending time width setting circuit, 4... AND gate, 5... Oscillation circuit, 6... Amplification circuit, 7, 8
...Ultrasonic transducer, 9...Amplification circuit, 10...Pulse shaping circuit, 11...And gate, 12...
Signal switching circuit, 13...Level detection circuit, 14...
...FM detection circuit, 15...Level detection circuit, 16
...Amplification circuit, 17...Nor gate, 18...Pulse width detection circuit, 19...Level detection circuit, 20
... Band pass filter, 21 ... Amplification circuit, 22
...Flip-flop, 23, 25...NAND gate, 24, 26...Pulse width detection circuit, 27...
...Output circuit, 28, 29...Drive circuit, C1-C
5... Capacitor, D1, D2... Diode,
G1, G2...Nor gate, IC1, IC6...Operation amplifier circuit, INV...Inverter, R1-R4...
...resistance, T _r ...transistor.

Claims (1)

[Claims] 1. A transmitting system that intermittently transmits ultrasonic waves with a predetermined time width into space, a receiving system that receives reflected waves from the space, an FM detection circuit that performs FM detection of the received signal, and a stationary object reflection separator that detects when the presence time width of a signal of a low frequency component contained in the output of the FM detection circuit and exceeding a predetermined level exceeds a predetermined value; a rain reflection separator that detects when the non-existence time width of a high frequency component signal that exceeds a predetermined level exceeds a predetermined value; and a detection output of the stationary object reflection separator and the rain reflection separator. An ultrasonic moving object detection device comprising: a gate section that operates an output circuit by performing a logical product with a detection output.