JPS5825318B2 - Vehicle monitoring device - Google Patents

Description

[Detailed Description of the Invention] The present invention is installed on the road side, constantly measures the traveling speed of vehicles passing through the measurement point, and when a speeding vehicle is detected,
The present invention relates to a vehicle monitoring device that triggers a camera for photographing a violation vehicle at an appropriate timing.

Speed measurements of conventional speeding vehicle photographing devices are performed based on the time the front wheels of the vehicle press on two footplate switches installed perpendicular to the direction of travel of the vehicle.

However, this poses a major problem in terms of mechanical strength and installation of the footboard switch.

On the other hand, it is also possible to use radar-type speed measuring devices, which have traditionally been used for speed enforcement, but these are originally used on the premise that police officers visually check violating vehicles. Since the microwave beam center is set parallel to the road surface, it has been impossible to limit the lanes to be detected to single lanes.

However, in the case of one lane, it is possible to limit the measurement lane by providing the radar with a direction discrimination function, but this becomes impossible when there are two or more lanes on one side.

The present invention eliminates the above-mentioned drawbacks regarding speed measurement and also enables the shutter trigger of the camera to be issued at an appropriate timing.

In order to limit the lanes to be detected by a speed measuring device using a Doppler radar, it is sufficient to set a vehicle sensing area where a Doppler signal of a certain level or higher is obtained when a vehicle passes on the road, as shown in FIG.

In FIG. 1, point A is the transmitting/receiving antenna attachment point of the Doppler radar, and as shown in the figure, the position in the S, H coordinate system is 0, 0, HA).

Point B is one point at the front end of the vehicle sensing area C, and these positions are assumed to be LD, SD, and HD.

For example, if a vehicle Z traveling at a speed of vm/sec is detected at point B, the Doppler signal frequency fd observed by the Doppler radar at this time is clear from Equation 1 % Equation % fo: Microwave frequency Equation 1 If the detection point A changes, even if the vehicle is traveling at the same speed, the speed measured by the Doppler radar will change.

In Figure 2, HA = 1.5 m, Hl) = 0.5
An example of a vehicle detection position where cos θ is constant when m is illustrated.

Based on the above explanation and Figure 2, in order to limit the lane in which the speed should be measured and to measure the speed in a state where the speed coefficient is constant regardless of the vehicle's lateral traveling position within the lane, the directivity of the antenna should be sharp. The antenna is set so that the front edge of the vehicle sensing area formed on the road matches the arbitrary constant cosθ curve shown in Figure 2, and the speed is measured using the Doppler signal obtained at the front edge of the vehicle sensing area. It can be seen that accurate speed measurement is possible by dividing the observed speed by the cos θ.

FIG. 3 shows this state, where a is the driving lane width, b is the shutter trigger position, C is the vehicle sensing area, d is the center of the microwave beam, and e is the antenna installation point.

However, when measuring speed, Doppler signal - period (one wave)
Since the vehicle travel distance l required to obtain the speed is , the vehicle travel distance required for speed measurement changes in proportion to the speed when the speed is measured using the Doppler signal wave number within a certain time, and therefore the speed coefficient c
osθ changes.

In order to prevent this, it is necessary to calculate the speed from the reciprocal of the time required to count the Doppler signal with a constant wave number N1.

In addition, the trigger for the shutter operation of the camera for photographing violating vehicles is obtained after obtaining the Doppler signal with the constant wave number N1, and then outputting the signal after a time period of a constant number N2 times the time required for counting N1, so that the shutter operation is triggered at a certain distance from the front edge of the vehicle sensing area. (11+12) Photographs can be taken where the vehicle is traveling.

here It is.

FIG. 4 shows a specific configuration example of the present invention, where 1 is a microwave oscillator whose oscillation frequency is fO.

2 is a circulator that sends most of the output of the microwave oscillator 1 to a transmitting/receiving antenna 3 (described later), supplies the remaining part to a mixer 4 as a local signal, and sends the reflected wave received by the antenna 3 to the mixer 4; 3 irradiates most of the output of the microwave oscillator 1 onto the road surface as a sharp beam, and receives reflected waves of the irradiated microwaves that have undergone a frequency shift proportional to the traveling speed of the vehicle under test. It is a transmitting and receiving antenna, and the direction of the microwave beam is set so that the direction of the microwave beam is aligned with the front end of the vehicle sensing area where reflected waves of a certain level or higher are obtained by passing the vehicle under test, or with an appropriate curve in the curve with a constant velocity coefficient. Set.

4 mixes the local signal, which is a part of the output of the microwave oscillator 1, and the received reflected wave, and outputs a Doppler signal having a frequency corresponding to a shift frequency proportional to the traveling speed of the vehicle to be measured; The mixer 5 is a band amplifier that amplifies only the frequency component signal (shown in FIG. 5A) corresponding to the speed range to be measured in the output of the mixer 4.

Reference numeral 6 denotes a level judgment circuit which outputs "+1ss" when the instantaneous level of the Doppler signal output from the band amplifier 5 is above a certain level, and otherwise outputs "°0"; becomes.

7 is a waveform shaping circuit that converts the output of the band amplifier 5 into the rectangular wave shown in FIG. Therefore, as shown in Figure 5-2, if Doppler signals with an amplitude above a certain level are continuous, the output will continue to be "1", and in other cases the output will be "O". It is.

9 is the Doppler continuity determination circuit 8 as shown in FIG.
The Doppler signal wave number is calculated immediately after the output becomes "1", and the output from the start of counting to the constant wave number N1 counting is calculated.
``In other cases, it is a wave number counting circuit that outputs ``0'', and during wave number counting, the output of the Doppler continuity judgment circuit 8 is ``''.
0", the wave number counted up to that point is reset and the output becomes f'099. Clause 10 is the number of clocks that correspond to the layer wave number f1 while the wave number counting circuit 9 outputs "1". This is a time counting circuit A that counts . Similarly to the wave number counting circuit 9, if the output of the Doppler continuity determination circuit 8 becomes '0' during counting, the counted value up to that point is reset.

11 counts up the number of clocks with interlayer wave number f1 for which the wave number counting circuit 9 outputs "1"; however, in the middle of this counting, the output of the Doppler continuity determination circuit 8 becomes "0".
If this happens, the count value up to that point will be reset),
After the wave number counting of the wave number counting circuit 9 is completed, the frequency f2 (
However, this is a time counting circuit B that counts down with the clock f2-f1/N2), and if the borrow output from this circuit is used as the shutter trigger timing of the camera, this position will be the same as the one at which the vehicle is sensed regardless of the position of the vehicle in the lateral direction of the road. A position advanced by the distance shown in formula 6 from the front end of the area in the direction of vehicle travel (
(See Figure 3).

13 is a division circuit that divides the speed (value of ) by the count value of the time counting circuit 10, and 13 compares the speed that is the output of the division circuit 12 with a preset speed, and if the speed is equal to or higher than the set speed, outputs. 1'' is held for a certain period of time, and otherwise outputs an output of ``0''; 14 is the comparison circuit 13;
This is a trigger signal generation circuit that generates a shutter trigger signal for the camera at the time when the time counting circuit 11 outputs a borrow output when the output is "1pa".

An outline of the operation of this embodiment will be explained.

Microwaves generated by the oscillator 1 are radiated onto the road surface via the antenna 3, and reflected waves from vehicles and the like are received again.

The reflected signal received by the antenna 3 and the direct output of the oscillator 1 are added to the mixer via the circulator 2, which includes the false beat component that generates the beat, and the signal in the necessary band is amplified by the amplifier 5. Then, the level determination circuit 6 generates a signal indicating a signal period above a certain level, and the circuit 7
to obtain a waveform-shaped signal.

The Doppler continuity determination circuit 8 detects the period during which the output of the circuit 6 is continuous based on the outputs of the circuits 6 and 7, and controls the wave number counting circuit to display the period of wave number N1 counting.

The time counting circuit 10 counts the number of slopes during that period, and the division circuit 12 divides the counted value by a constant value to output a signal indicating the speed.

Comparison circuit 13 detects that this speed signal is higher than a preset level, and after a period of time controlled by time counting circuit 11 has elapsed, circuit 14 generates a signal to trigger the shutter of the camera.

As described above, according to the present invention, it is possible to accurately measure the traveling speed of vehicles within one driving lane without carrying out any construction work on the road, and at the same time trigger the shutter of the camera for photographing the violating vehicle at an appropriate timing. I can do it.

Furthermore, since this device requires a relatively simple configuration, it can be made portable, which is advantageous in practice.

[Brief explanation of the drawing]

1 and 3 are schematic diagrams showing the principle of the present invention, FIG. 2 is a diagram showing the horizontal position of the vehicle, and FIG. 4 is a block diagram of a vehicle monitoring device according to an embodiment of the present invention. Figure 5 shows its characteristic diagram. 3... Transmitting/receiving antenna, 12... Division circuit, 13
... Comparison circuit, 14... Trigger signal generation circuit.

Claims (1)

[Scope of Claims] 1. A vehicle sensing area in which a Doppler signal of a certain level or higher is obtained when a vehicle passes through is detected by all vehicles passing through the middle of the road to be detected, and the Doppler signal at the front end of the sensing area is detected. An antenna with sharp directivity is installed on the road side and the mounting height and direction are determined so that the signal frequency has a relationship determined by a constant proportional constant to the vehicle speed regardless of the vehicle being measured's traveling position in the cross-road direction. , a means for measuring the running speed of the vehicle to be measured using a Doppler signal of a certain level or higher at a certain wave number N1 and a time T required for counting, and comparing the measured speed with a predetermined set value to obtain a predetermined comparison result. The vehicle monitoring device is characterized in that it is provided with a means for generating a trigger signal to operate a shutter of a camera for photographing a passing vehicle only when the time T is counted and a certain number N2 times the time T has elapsed from immediately after the time T count. 2. The set value for comparing the measured speeds corresponds to a speed corresponding to a speed violation, and the predetermined comparison result is obtained when the measured speed exceeds the set value. Vehicle monitoring device according to item 1.