JPH0243154B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ultrasonic Doppler vehicle detector.

BACKGROUND TECHNOLOGY In general, an ultrasonic Doppler type vehicle detector continuously transmits ultrasonic waves to a moving vehicle, and the reflected waves are reflected by the moving vehicle. The device is configured to measure the running speed, presence, number, etc. of the vehicles by detecting what kind of Doppler effect the vehicle has received and analyzing the frequency, envelope, etc. of the reflected wave that has received the Doppler effect. It is something. Therefore, ultrasonic Doppler type vehicle detectors can detect the speed, presence, number, etc. of running vehicles extremely accurately, and have been widely used in the past.

Problems to be Solved by the Invention However, all of the conventionally used ultrasonic Doppler type vehicle detectors are based on the analysis of the frequency, envelope, etc. of the reflected waves subjected to the Doppler effect. , detects the traveling speed, presence, number of vehicles, etc. When the vehicle travels at a low speed of about 10km/h or less, the Doppler effect of the reflected waves itself becomes small, and the speed, presence, and number of vehicles are detected. There was a problem in that it became very difficult to detect such things, and it became almost impossible to detect them when the vehicle was stopped.

In particular, when detecting the presence and number of vehicles,
Since it is necessary to analyze how the envelope of the reflected wave changes due to the Dotsuppler effect and perform detection based on that result, changes in the envelope become almost impossible to detect in low-speed vehicles. However, there was a problem in that the accuracy of detecting the presence and number of vehicles was significantly reduced.

The present invention solves the above-mentioned conventional drawbacks, and uses a simple configuration to accurately detect the presence of a stopped or slow-moving vehicle.
The purpose is to provide an excellent vehicle detector that can measure the number of vehicles.

Means for Solving the Problems In order to solve the above problems, the present invention adds a reflected pulse detection circuit to a Doppler type vehicle detector, and as a result of measuring the average running speed of the vehicle by the Doppler type vehicle detector, If the average running speed of the vehicle is faster than the predetermined reference speed, it will operate as a Doppler vehicle detector, and if the average running speed of the vehicle is below the reference speed, the signal will be transmitted from the wave transmitting head. The ultrasonic wave is converted into a so-called ultrasonic burst signal that is transmitted with a certain width at each predetermined period, and the reflected wave of the burst signal from the vehicle is detected by the reflected pulse detection circuit to detect the presence of the vehicle. In addition, when the reflected pulse detection circuit detects the presence of a vehicle, it temporarily operates as a Doppler type vehicle detector, and the average running speed of the detected vehicle is set to the reference speed. Depending on whether the vehicle is faster or faster, it will automatically select whether to continue operating as a Doppler vehicle detector or to have the reflected pulse detection circuit detect the presence of a vehicle again. It is composed of

Effect Therefore, according to the present invention, even if the average running speed of the vehicle falls below a predetermined reference speed and the Doppler type vehicle detector cannot accurately detect the presence of a vehicle, reflected pulse detection is possible. Since the circuit accurately detects this, it has the effect that the traveling speed, presence, number, etc. of the vehicles can be accurately measured based on the detection results. According to the present invention, once the presence of a vehicle is detected by the reflected pulse detection circuit, it is configured to operate as a Doppler vehicle detector. In the operation, the average running speed of the vehicle is detected, and if the result is faster than the reference speed, it will continue to operate as a Doppler type vehicle detector, and the running speed, number of vehicles, and average running speed will be determined. It has the effect of being able to detect extremely accurately in either case.

Embodiment FIG. 1 is an explanatory diagram illustrating the operation mode of the vehicle detector of the present invention. As is clear from FIG. 1, the vehicle detector of the present invention operates in the same way as the conventional ultrasonic Doppler vehicle detector when the average running speed of the vehicle is faster than a predetermined reference speed. However, when the average running speed of the vehicle falls below the above reference speed, the transmitted ultrasonic wave becomes an ultrasonic burst signal, and the presence of the vehicle is detected by detecting the reflected wave. It performs a so-called reflected pulse detection type operation, and if it detects the presence of a vehicle, it again operates as the Doppler type vehicle detector. Therefore, if the average running speed of the vehicle is detected to be less than the reference speed in the operation as a Doppler type vehicle detector, the operation returns to the reflected pulse detection type and the above operation is repeated. If it is detected that the average running speed of the vehicle has become faster than the reference speed, the operation as the Doppler type vehicle detector continues as is.

FIG. 2 is a block diagram showing the configuration of one embodiment of the vehicle detector of the present invention, in which 1 indicates continuous ultrasonic waves in response to a mode switching signal, that is, an ultrasonic continuous signal, 3 is a transmitting signal generating circuit that outputs any of the so-called ultrasonic burst signals that emit to its output line 2, 3 is the above-mentioned continuous ultrasonic signal from the transmitting signal generating circuit 1,
4 is a wave transmitting amplifier circuit that amplifies each ultrasonic burst signal, 4 is a wave transmitting head that converts the output of the wave transmitting amplifier circuit 3 into ultrasonic waves, and transmits the waves toward the driving area of the vehicle; A receiving head 6 receives the reflected wave reflected by the receiving head 5, and a continuous ultrasonic wave is generated by combining the reflected wave received by the receiving head 5 and subjected to the Doppler effect and the transmitted signal generating circuit 1. A Doppler detection circuit 8 compares a part of the Doppler signal with the Doppler signal, extracts only the Doppler signal, and outputs it to an output line 7. 8 analyzes the frequency and envelope of the Doppler signal detected by the Doppler detection circuit 6. The running speed of the vehicles, the number of vehicles, the average running speed per certain number of vehicles, etc. are calculated using , 11; 12 is a reflected pulse detection circuit that receives a pulse based on the reflected wave of the ultrasonic burst signal received by the receiving head 5 and detects the presence of a vehicle; 14 is a speed calculation circuit; Output line 11 of arithmetic circuit 8
The average traveling speed signal corresponding to the average traveling speed of the vehicle outputted to the reference speed signal line 17 is compared with the reference speed signal corresponding to a predetermined reference speed applied to the reference speed signal line 17, and the average traveling speed is higher than the reference speed. Sometimes a mode switching signal to the first mode;
When it is less than that, a comparison circuit outputs a mode switching signal to the second mode, and 19 is a number signal corresponding to the number of vehicles outputted to the output line 10 of the speed calculation circuit 8 and the output of the reflected pulse detection circuit 12. line 1
This is an OR circuit that inputs the Occupancy signal corresponding to the presence of a vehicle outputted to 8 and outputs the respective signals.

Note that the reflected pulse detection circuit 12 is a comparison circuit 14.
The speed calculation circuit 8 is configured to operate when a mode switching signal to the second mode is output.
is configured to operate when the comparison circuit 14 outputs a mode switching signal to the first mode. Further, the reflected pulse detection circuit 12 receives the reception signal from the reception head 5 in synchronization with the synchronization signal output every time an ultrasonic burst signal is output from the transmission signal generation circuit 1, and detects the presence of a vehicle. is configured to do so. In addition, the comparison circuit 18
When the reflected pulse detection circuit 12 detects the presence of a vehicle and a signal corresponding to the presence appears on the output line 18, the mode is switched to the first mode regardless of the value of the average running speed signal from the speed calculation circuit 8. It is configured to output a mode switching signal.

Next, the operation of the above embodiment will be explained.

In FIG. 2, it is assumed that the operation mode is now in the first mode. In this case, the transmission signal generation circuit 1
A continuous ultrasonic wave, that is, an ultrasonic continuous wave signal is outputted from the transmitter, and is applied to a transmitting amplifier circuit 3 and a Doppler detecting circuit 6 via an output line 2. The above-mentioned continuous ultrasonic signal being applied to the transmission amplification circuit 3 is amplified to an appropriate level here,
The waves are transmitted via the wave transmitting head 4 toward the vehicle driving area. When a vehicle exists in the vehicle travel area, the transmitted ultrasonic continuous wave is reflected by the vehicle, and the reflected wave is received by the wave receiving head 5 and applied to the Doppler detection circuit 6. Ru.

The Doppler detection circuit 6 mixes the reflected wave received by the reception head 5 with a part of the ultrasonic continuous wave from the transmission signal generation circuit 1, thereby
Only the Doppler signal proportional to the magnitude of the Doppler effect received by the vehicle is detected and applied to the speed calculation circuit 8 via the output line 7.

The speed calculation circuit 8 calculates the frequency and envelope of the Doppler signal from the Doppler detection circuit 6 by utilizing the fact that the frequency of the Doppler signal is proportional to the traveling speed of the vehicle and a change in the envelope indicates the presence of a vehicle. The analysis is performed, and based on the results, the running speed of the vehicles, the number of vehicles, the average running speed per certain number of vehicles, etc. are calculated. Then, respective signals corresponding to the traveling speed, the number of vehicles, and the average traveling speed are outputted to the respective output lines 9, 10, and 11.

The average running speed signal outputted to the output line 11 is applied to the comparison circuit 14, where it is compared with a predetermined reference speed, for example, a reference speed signal corresponding to 10 km/h. When the average running speed is faster than the reference speed, the comparison circuit 14 outputs a mode switching signal to the first mode, and the transmission signal generation circuit 1 maintains the first mode and outputs a continuous ultrasonic signal. , that is, it continues to output continuous ultrasonic signals. Therefore, in this case, the previous operations are repeated to accurately calculate the running speed, number of vehicles, occupant load, etc.

When the average traveling speed is faster than the reference speed, the mode switching signal to the first mode from the comparison circuit 1 is applied to the reflected pulse detection circuit 12 in the same phase, and the phase inverted signal is applied to the speed calculation circuit 8. Therefore, the reflected pulse detection circuit 12 remains inactive, and the speed calculation circuit 8 remains active.

Next, assume that in this state, the average traveling speed of the vehicle becomes equal to or less than the predetermined reference speed. When the average running speed of the vehicle becomes below the reference speed, it is detected by the comparator circuit 14, and the second
A mode switching signal to the mode is output. Second
The mode switching signal to the mode is first applied to the reflected pulse detection circuit 12 with the same phase, and then applied to the speed calculation circuit 8 with the phase reversed. Therefore, first, in this state, the reflected pulse detection circuit 12 becomes active, and the speed calculation circuit 8 becomes non-active.

The mode switching signal to the second mode is further applied to the transmission signal generation circuit 1, and the operation mode of the transmission signal generation circuit 1 is switched to the second mode.
Therefore, in this state, the transmission signal generation circuit 1 outputs a so-called ultrasonic burst signal that emits ultrasonic waves of a constant width at regular intervals. and,
The ultrasonic burst signal outputted by the transmission signal generation circuit 1 is applied to the transmission amplifier circuit 3 via the output line 2, where it is amplified to an appropriate level and sent to the vehicle via the transmission head 4. Waves are transmitted to the driving area.

FIG. 3 shows the output waveforms of each part when the average running speed of the vehicle is below the above-mentioned reference speed, and 20 shows the output waveform of the transmission signal generation circuit 1. That is, when the average running speed of the vehicle is below the reference speed, first, the transmission signal generation circuit 1
From this, a so-called ultrasonic burst signal is output which emits ultrasonic waves of a constant width at regular intervals as shown in FIG.

When a vehicle exists in the vehicle travel area, the transmitted ultrasonic burst signal is reflected by the vehicle, and the reflected wave is received by the wave receiving head 5. The received reflected wave is applied to a reflected pulse detection circuit 12, which determines whether the reflected wave is caused by a vehicle, distinguishing it from road surfaces or other objects, based on the level of the reflected wave, the timing of receiving the reflected wave, etc. to detect the presence of a vehicle. That is, as explained earlier, the reflected pulse detection circuit 12 is configured to input the reception signal from the reception head 5 in synchronization with the synchronization signal (22 in FIG. 3) from the transmission signal generation circuit 1. Therefore, reflected waves other than the transmitted ultrasonic burst signal are cut off and not detected, and only the reflected waves of the transmitted ultrasonic burst signal are detected.
Since the level of reflected waves is generally higher at a vehicle than at a road surface, the presence of a vehicle is detected by this.

When the reflected pulse detection circuit 12 detects the presence of a vehicle and outputs an occupancy signal to its output line 18, its rising edge is detected by the comparator circuit 14, which causes the comparator circuit 14 to temporarily switch to the first A mode switching signal to the mode will be output. When the comparator circuit 14 outputs a mode switching signal to the first mode, the speed calculation circuit 8 becomes operational, the reflected pulse detection circuit 12 becomes inactive, and the transmission signal generation circuit 1 outputs a continuous signal. The resulting ultrasonic wave, that is, an ultrasonic continuous signal, is output. Therefore, in this state, the Doppler detection circuit 6 and the speed calculation circuit 8 calculate the running speed, number of vehicles, average running speed, etc. of the vehicles again.
As a result of the calculation, if the average running speed is higher than the reference speed, the comparator circuit 14 directly outputs a mode switching signal to the first mode, and the above calculation is repeated.

If the average running speed is below the reference speed, the comparator circuit 14 outputs a mode switching signal to the second mode, and the reflected pulse detection circuit 12 detects the presence of a vehicle again. It will be done.

In this case, the occupancy signal from the reflected pulse detection circuit 12 is maintained until the vehicle leaves the sensing area, the reflected wave from the vehicle disappears, and a certain period of time has elapsed. Therefore, the occupancy signal is not reset not only when the vehicle is within the sensing area but also after a certain period of time has elapsed, during which time the reflected pulse detection circuit 12 detects the presence of the vehicle detector. Even if detected, the comparator circuit will not output a mode switching signal to the first mode again. That is, according to the above embodiment, the third
As shown in the figure, even if the reflected pulse detection circuit 12 immediately detects the presence of a vehicle after the second mode is entered and the average traveling speed is determined to be below the reference speed in that state, In that case, there is a strong possibility that the same vehicle exists only within the sensing area, so that the comparator circuit 14 will not output a mode switching signal to the first mode. When the vehicle leaves the sensing area and the reflected pulse detection circuit 12 no longer detects the reflected wave from the vehicle, the occupancy signal is reset after a certain period of time has elapsed. When the reflected wave from the vehicle is detected, the rising edge of the occupancy signal appears for the first time, and the comparator circuit 14 outputs a mode switching signal to the first mode.

In addition, in the example, if there is a Doppler signal even though there is a reflected wave from the vehicle, or if there is a Doppler signal but the frequency is below a certain level, the vehicle is stopped or in a state close to it. The system is configured to determine that the traveling speed of the vehicle is zero.

Further, FIG. 3 shows the output waveforms of each part during the operation described above. In FIG. 3, 20 is a transmitted signal from the transmitted signal generation circuit 1, 21 is an example of a received signal by the reception head 5, and 22 is applied from the transmitted signal generation circuit 1 to the reflected pulse detection circuit 12. 23 is a mode switching signal output from the comparison circuit 14, 24 is a number and occupancy signal output from the OR circuit 19, and 25 is a speed signal from the speed calculation circuit 8. and,
26 is an ultrasonic burst signal, 27 is a reflected wave from the road surface, 28 is a reflected wave from a vehicle, 29 is a mode switching signal to the second mode, 30 is a mode switching signal to the first mode, and 31 is the previously calculated signal. The vehicle speed signal 32 is the vehicle speed signal calculated this time.

Effects of the Invention As is clear from the above embodiments, according to the present invention, when a vehicle is traveling faster than a predetermined reference speed, it operates as a Doppler vehicle detector in the same way as the conventional one. Therefore, in this case, the traveling speed of the vehicle is
The presence and number of devices can be detected extremely accurately, just like before. The device is configured to automatically operate as a reflected pulse type vehicle detector when the vehicle's running speed falls below the above-mentioned reference speed. can also accurately detect the presence of the vehicle, and once the presence of the vehicle is detected,
Due to its rise, it will operate as a Doppler-type vehicle detector again, and if the traveling speed of the vehicle is detected during operation as a Doppler-type vehicle detector, the Doppler-type vehicle detector will be activated depending on the result. , the reflected pulse type vehicle detector will be selected again, and the above operation will be repeated. Therefore, according to the present invention, the presence of a vehicle can be detected extremely accurately not only when the traveling speed of the vehicle is faster than the reference speed but also when the vehicle is lower than the reference speed, and the detection results are Based on this information, the traveling speed and number of vehicles can be detected extremely accurately.

Although the embodiment is configured to compare the average running speed of the vehicle with the reference speed, it goes without saying that the configuration may be configured to simply compare the running speed of the vehicle.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining the operation mode of the vehicle detector of the present invention, FIG. 2 is a block diagram of an embodiment of the vehicle detector of the present invention, and FIG. FIG. 4 is an output waveform diagram of each part of the above embodiment in the case of FIG. DESCRIPTION OF SYMBOLS 1... Transmission signal generation circuit, 3... Transmission amplification circuit, 4... Transmission head, 5... Wave reception head, 6...
... Doppler detection circuit, 8 ... Speed calculation circuit, 12
... Reflected pulse detection circuit, 14 ... Comparison circuit, 1
9...OR circuit.

Claims (1)

[Claims] 1. A transmitting signal generating circuit capable of switching between a first mode that outputs a continuous ultrasonic signal and a second mode that outputs an ultrasonic burst signal according to a mode switching signal; a wave transmitting head that transmits the output of the wave signal generation circuit toward a driving area of the vehicle; and a wave receiving head that receives the reflected wave of the ultrasonic wave transmitted by the wave transmitting head and reflected by the vehicle. , a Doppler detection circuit that detects a Doppler signal based on the reflected wave received by the reception head and the output of the transmission signal generation circuit; and the Doppler signal detected by the Doppler detection circuit. Based on the frequency and envelope of the vehicle, the traveling speed, number of vehicles,
A speed calculation circuit that calculates the average running speed, etc. compares the parallel running speed obtained by the above calculation circuit with a predetermined reference speed, and when the average running speed is faster than the reference speed, it switches to the first mode. a comparison circuit that outputs a mode switching signal and a mode switching signal to a second mode when the mode is slow, and detecting the reflected wave received by the receiving head;
A reflected pulse detection circuit detects the presence of a vehicle based on the reflected pulse detection circuit, and when the average running speed obtained by the calculation circuit is faster than a predetermined reference speed, the comparison circuit switches the mode to the first mode. The transmission signal generation circuit is switched to the first mode by the signal, a continuous ultrasonic wave is transmitted from the transmission head, and the Doppler detection circuit and speed calculation circuit detect the running speed, number of vehicles, and average running speed of the vehicles. etc., and when the average traveling speed is lower than the reference speed, the transmission signal generation circuit is switched to the second mode by a mode switching signal from the comparison circuit to the second mode, and the An ultrasonic burst signal is transmitted from the transmitting head, the presence of a vehicle is detected by a reflected pulse detection circuit, and when the presence of a vehicle is detected, the output is used to temporarily select the first mode from the comparison circuit. A vehicle detector configured to output a mode switching signal. 2 A comparative circuit is configured to compare a vehicle running speed signal and a reference speed signal, and output mode switching signals to the first mode and the second mode, respectively, based on the comparison result. Vehicle detector according to scope 1.