JPS6235158B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention provides a vehicle speed measuring device, more specifically, a set area and a reset area are provided at a required distance from a vehicle speed detection point, and when a vehicle passes from the set area to the reset area. The present invention relates to a device that detects the speed of a vehicle based on a time difference between obtained video signals (vehicle detection signals).

Such vehicle speed measurement devices typically
The vehicle detection signal in the set area is output first, and then the vehicle detection signal in the reset area is output. However, for some reason, the order of the vehicle detection signals may be reversed. For example, this may be the case when the shadow of a vehicle passing in an adjacent lane is detected.

The present invention provides a speed measuring device that can always accurately measure the running speed of a vehicle by measuring the speed of the vehicle only in normal cases where a vehicle detection signal in the reset region is output after the set region. It is something to do.

The vehicle speed measuring device according to the present invention includes a light receiving element that outputs video signals of a vehicle passing through a set area and a reset area set at a required distance from a vehicle speed detection point as a set signal and a reset signal, respectively; means for sampling each of the reset signals at a predetermined period; means for determining the deviation between the current sampling value and the previous sampling value for each of the set signal and the reset signal; and a reference value, and if the absolute value of the deviation is larger than a predetermined reference value, it is determined that the state is in an increasing state or a decreasing state, and a means for storing this determination result, and there is no memory of the above determination. means for detecting the rise or fall of the set signal and reset signal from the road surface level by determining that it is the first increasing state or decreasing state based on the above, and storing this;
For each of the set signal and reset signal, if the signal does not rise or fall from the road surface level, it is detected that the road surface level has been exceeded based on the fact that the deviation between the current sampling value and the road surface level is greater than or equal to a predetermined vehicle confirmation level. a timer that starts counting from zero upon detection of a rising or falling edge of the set signal from the road surface level or exceeding the road surface level; and a timer that starts counting from zero when the rising edge of the reset signal is detected; If so, if there is a memory of detecting the falling of the set signal when the falling of the reset signal is detected and there is no memory of crossing the road, or when the falling of the reset signal is detected, there is a memory of detecting the falling of the set signal. If the vehicle is stored, the vehicle is characterized by comprising means for calculating the vehicle speed based on the time measured by the timer and the required distance at that time.

In the present invention, not only the rising edge but also the falling edge of the detection signal of a vehicle passing through the set area and the reset area, that is, the set signal and the reset signal, and the exceeding of the road surface level are detected. Then, only if the rising edge, falling edge, or exceeding the road surface level of the set signal occurs before the rising edge, falling edge, or exceeding the road surface level of the reset signal, the rising edge to rising edge, falling edge to falling edge, or Since the time from when the vehicle crosses the road surface to when it crosses the road surface is detected, and the vehicle speed is measured based on this detection time, accurate vehicle speed measurement can be performed at all times.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

The example shown below is a case where a traffic flow measuring device installed at a position overlooking the road and having a large number of light receiving elements is used. This device has the advantage of being able to collect vehicle information from multiple points on the road at one location and being easy to install.

FIG. 1 shows how the camera of the traffic flow measuring device is installed. The camera 1 is located at a required height above the road L (for example, 6 m) using the support 3 etc.
, the required range in the length direction of the road L (for example, 100
m) is installed so as to provide a bird's-eye view of the area. camera 1
Inside, as shown in FIG. 3, an optical system 4 including a lens 5 and a large number of light receiving elements is provided. In this example, within the field of view of the camera 1, there are six detection points P1 to P6 along the lane in which traffic flow is to be measured. Pairs of light receiving elements d _S 1, d _R 1 to d _S 6, d _R 6 are arranged at locations corresponding to these detection points on the image forming plane of the optical system 4 in the camera 1. ing. These light receiving elements are composed of photo diodes, for example. When measuring traffic flow in two lanes with one camera, a large number of light receiving elements are arranged in two rows on the imaging plane of the optical system 4. As shown in FIG. 2, at each detection point (represented by P), a set area S and a reset area R are set at a required interval l. A pair of light receiving elements (represented by d _S and d _R ) correspond to these regions S and R, respectively. When the vehicle CA passes through the detection point P from the set area S to the reset area R, a vehicle detection video signal shifted by a time t from the light receiving elements d _S and d _R is outputted, as will be described later. Then, the traveling speed of the vehicle is calculated based on this time t and distance l.

The processing device 2 obtains traffic flow information such as vehicle running speed, headway distance, degree of traffic congestion, number of passing vehicles, and other information based on video signals from the camera 1 . Third
Referring to the figure, each light receiving element d _S , d _R in camera 1
After the output signal is amplified by an amplifier 6 equipped with an automatic gain control function, it is sent to a multiplexer channel device 7, where the outputs of each of the 12 light receiving elements are sequentially switched and output from A to D. It is sent to converter 8. The A-D converter 8 operates at a predetermined period (in this example,
4.8ms), the output of the input light receiving element is AD converted, and the result is sent to the central processing unit (CPU) 1.
Send to 1.

The processing device 2 is equipped with two CPUs 11 and 12. Based on the data sent from the A-D converter 8, the CPU 11 analyzes the output signal waveform of each light-receiving element, and also analyzes the output signal waveform of each light-receiving element based on the data sent from the A-D converter 8. Controls the D converter 8. The CPU 12 calculates the vehicle speed, detects the degree of congestion, and performs other traffic flow calculations based on the data obtained by the CPU 11, and also creates necessary traffic flow information and sends it to a transmission unit (not shown). The data is then transmitted to the center. Each CPU 11, 12 is
In addition to a program memory (not shown) that stores execution programs, the processing device 2 includes local memories 13 and 14 that store data, and a shared memory 15 that can be accessed by both CPUs 11 and 12. be.

4a to 4g show light receiving elements d _S , d _R
An example of a vehicle video signal output from a vehicle is shown. The set signal is the output of the light receiving element _dS , and the reset signal is the output of the light receiving element _dR . 4th a
The figure shows the most common video signals. Since the vehicle reflects more light than the road surface, when the vehicle reaches the detection point P, the output of the light receiving element becomes higher than the level at which the road surface is detected (road surface level L0). Then, when the vehicle passes, the output of the light receiving element returns to the road surface level L0 again. Therefore, the time from the rising edge of the set signal waveform to the rising edge of the reset signal waveform is defined as the detection time t. Since this detection time t is the time required for the vehicle to travel between the set area S and the reset area R (distance l), the traveling speed V of this vehicle is determined by the following equation.
However, K is a constant.

V=K・l/t The distance that a vehicle actually moves during the detection time t varies slightly depending on the vehicle due to the influence of the vehicle shape, vehicle height, etc., and is not actually equal to the above distance l. . However, by imagining a sensing surface at a position above the road surface by the required height, measuring the distance between both areas S and R on this sensing surface, and statistically correcting this distance, it is possible to increase the vehicle's running speed. It is possible to measure with high precision.

The signal waveform shown in FIG. 4b has a peak reaching a very high level. Therefore, a cutoff level L1 is set at an appropriate level, and the difference between the times when the set signal and the reset signal each exceed the cutoff level L1 is defined as the detection time t. Then, using this detection time t, the traveling speed V is calculated using the above-mentioned formula.

The signal waveform shown in FIG. 4c includes a signal component A lower than the road surface level L0 at the front. This signal component A is due to a shadow appearing in front or behind the vehicle. When there is a shadow, the amount of light from that area decreases, so the signal becomes lower than the road surface level L0. In the case of such signal waveforms, the time points at which the set signal and the reset signal each exceed the road surface level L0 are detected, and the time difference between these times is defined as the detection time t. In addition, for the waveform in FIG. 4c, in order to confirm that there is a signal component caused by the vehicle following the component A caused by the shadow, a vehicle confirmation level L2 is provided, and the signal level increases across the road surface level L0. Then, it is checked whether this level L2 has been exceeded. The light receiving element may detect the shadow of a vehicle traveling in an adjacent lane. The signal due to this shadow shows a level lower than the road surface level L0 like component A, but it may reach a level slightly higher than the road surface level L0 at the rear. but,
This slightly higher level signal component at the rear never becomes higher than the confirmation level L2, so the confirmation level L2 can be used to distinguish between a signal caused by a vehicle and a signal caused by the shadow of a vehicle traveling in another lane. I can do it.

The signal waveform shown in FIG. 4d also includes signal components A and B due to shadows. However, the fall of the reset signal occurs earlier than the fall of the set signal. Component B due to the shadow of the reset signal
This appears when the shadow of the own vehicle overlaps with the shadow of an adjacent vehicle traveling in another lane. Even in the case of such a signal waveform, the time points at which each signal exceeds the road surface level L0 (more precisely, the level L2) are detected, and the time difference between these points is determined as the detection time t.
shall be.

In the signal waveform shown in FIG. 4e, the reset signal rises earlier than the set signal. Since such a phenomenon is impossible, treat it as an error.
Detection time, which is the basis for calculating running speed, is not measured.

The signal waveform shown in Fig. 4f is a waveform that appears when the bus passes the detection point P, and is at the road surface level L.
It rises from 0 and increases, and when it reaches a peak, this peak level remains flat for a while without increasing or decreasing, and then decreases to the road surface level L0. Regarding such a signal waveform, the time difference between the rising points of the set signal and the reset signal is defined as the detection time t, as in the waveform shown in FIG. 4a. A state in which the signal level neither increases nor decreases is called an equilibrium state. When no vehicle is detected, the output of the light receiving element is at the road surface level L0, maintaining an equilibrium state. Also, the peak of the signal shown in Fig. 4f
The level is also in equilibrium. In this way, there are two levels in the equilibrium state, and in order to distinguish between them, the road surface identification level L3 is set at a position midway between the two levels.

The signal waveform shown in Figure 4g is similar to that shown in Figure 4c and includes a component A due to shadows appearing in front or behind the vehicle. However, in the signal shown in FIG. 4c, the fall of the reset signal occurs earlier than the point at which the set signal crosses the road surface level L0, whereas in FIG. This occurs later than the time when the road surface level L0 is crossed. For such signal waveforms as well, the time difference between the set signal and the reset signal when they cross the road surface level L0 is defined as the detection time t.
shall be.

In order to detect the rise or fall of the output signal waveform of the light receiving element, it is necessary to determine the change in the signal. Since the output signal of the light-receiving element is AD-converted by the A-D converter 8 every sampling period, the current AD-converted result is set as the current data Dt.
In order to determine whether the current data Dt is increasing, decreasing, or in equilibrium compared to the previous data, it is necessary to find the deviation Δω between the current data Dt and the previous data. .
Previous data to be used for determining this deviation Δω is defined as preprocessed data D0. This preprocessed data D0 is, for example, previously sampled data and is updated every sampling period. Furthermore, for the above determination, the reference amount to be compared with the deviation Δω between the current data Dt and the pre-processed data D0 is defined as the deviation reference amount ω0. And Dt-D
If 0≧ω0, increasing state, Dt−D0≦−ω0
If so, it is a decreasing state |Dt-D0|<ω0, it is an equilibrium state. FIG. 5 shows how the change in the signal is determined for each sampling period in this manner.

In the above, for convenience, the preprocessed data D0 is updated every sampling period regardless of the signal state, but by introducing the concept of a prescribed period, this is updated multiple times (for example, four times) the sampling period.
, the deviation Δω is compared with the reference amount ω0 at each sampling period, and the deviation Δω is the reference amount ω0.
In this case, or when the prescribed period T has elapsed, it is desirable to update the preprocessing data by using the current data Dt as the preprocessing data D0. If the rise or fall of the signal is slow, the amount of increase or decrease is equal to the reference amount ω during the sampling period.
It may not reach 0. The prescribed period is introduced to detect slow changes in such signals,
It is checked whether the amount of change has reached the reference amount ω0 within the specified period. The method for detecting such a change in waveform can be summarized as follows. If Dt-D0≧ω0 within the specified period, it is considered to be an increasing state, and if Dt-D0-≦ω0 within the specified period, it is considered to be a decreasing state. Then, when these determinations are made, the current data Dt is adopted as the preprocessed data D0. Also, even if the specified period has passed, |Dt−D
If 0|<ω0, it is regarded as an equilibrium state, and the current data Dt is adopted as the preprocessed data D0.

Waveform analysis processing of the output video signal of the light receiving element
Memory 13, 15 for CPU 11 to execute
Various data are stored in the . In the memory 13,
Current data of set signal and reset signal
There is an area for storing Dt, preprocessed data D0, deviation Δω, and road surface level L0, and an area for storing the start pattern of the set signal. The start pattern indicates a change in the condition (increase or decrease) after a certain period of time (this is referred to as end confirmation time T1) has passed while the set signal is in an equilibrium state and the road surface level L0 is maintained. It's a pattern. This is used to check whether the vehicle detection signal first rises or falls. The end confirmation time T1 is a time provided to confirm that one vehicle has passed the detection point in order to clearly distinguish individual vehicles.

The memory 13 also includes areas used as various flags. The set signal flag F1 and the reset signal flag F11 indicate that one vehicle is passing through the set area S and the reset area R and a vehicle detection signal is output, respectively. The output of each light-receiving element rises or falls from the road surface level L0, changes as required, and then returns to the road surface level L0.
It becomes an equilibrium state, and is kept on while maintaining the road surface level L0 until the end confirmation time T1 has elapsed. The set signal temporary end flag F2 and the reset signal temporary end flag F12 indicate that the end confirmation time T1 of each set and reset signal is being measured, and when the signal returns to the equilibrium state at the road surface level L0. It is turned on, and turned off when the end confirmation time T1 has elapsed. The set signal start flag F3 indicates that the detection time t (vehicle speed) is being measured, and is set when the set signal rises from the road surface level L0, when the set signal falls from the road surface level L0, and when the set signal crosses the road surface level L0 in an increasing state. It is turned on when the reset signal is turned off, and when the reset signal rises and falls from the road surface level L0, and when the reset signal
It is turned off when it crosses 0 in an increasing state. The set signal restart flag F4 indicates that signal components A and B due to the shadow of the vehicle are being measured, and is turned on when the set signal falls from the road surface level L0.
It is turned off when the vehicle falls from the ground and crosses the road surface level in an increasing manner. Repeat start flag F
5 indicates that the detection time t is being measured based on the cutting level L1, and is turned on when the set signal crosses the cutting level L1 in an increasing state, and is turned on when the reset signal is in an increasing state and disconnects. Level L1
It is considered off when it crosses the Recollection flag F
6 represents that the detection time t was measured with reference to the cutting level L1, and is turned on when the repeat start flag F5 is on and the reset signal crosses the cutting level L1 in an increasing state; Reset signal returns to road surface level L0 and completion confirmation time T
It is turned off when 1 has elapsed. The road surface crossing flag F7 is set when the set signal first falls to a level lower than the road surface level L0 and then exceeds the road surface level L0, and is used to store that the set signal has exceeded the road surface level L0. be. Similarly, this flag F7 is turned off when the reset signal exceeds the road surface level L0.
The data abnormality flag F13 is turned on when the rising and falling orders of the set signal and the reset signal are reversed. Reset signal start flag F14
is turned on when the reset signal first starts rising or falling, and is immediately turned off.

Further, predetermined areas of the memory 13 are used as a vehicle speed counter C1, a re-vehicle speed counter C2, and an after-end time counter C3. The vehicle speed counter C1 counts the detection time t based on the road surface level L0, and its contents are as follows: the set signal rises from the road surface level L0,
It is cleared when the road surface level L0 is crossed in a falling or increasing state, and time measurement is started from these points. The re-vehicle speed counter C2 is at the cutting level L.
1, and is cleared when the set signal crosses the cutting level L1 in an increasing state. Both of these counters C
1 and C2 are expressed as if two are provided for convenience of explanation, but one area may be shared by both counters C1 and C2. The post-completion time counter C3 measures the completion confirmation time T1. This counter C3 is provided one each for the set signal and the reset signal.
To simplify the explanation, C3 is used as a representative. Counter C3 counts if the set signal flag F1 (reset signal flag F11) is on and the set temporary end flag F2 (reset signal temporary end flag F1) is on.
2) is off, the set signal (reset signal) is cleared when it reaches the road surface level L0 in an equilibrium state, and the measurement operation starts from this point.

The shared memory 15 includes areas for storing deviation reference amount ω0, cutting level L1, vehicle confirmation level L2, road surface discrimination level L3, end confirmation time T1, and abnormal speed count number CM. For example, when the shadow of a vehicle traveling in an adjacent lane is detected, the output signal of the light receiving element falls from the road surface level L0, changes to a predetermined value, and then returns to the road surface level L0.
However, due to the characteristics of the circuit (especially the amplifier 6), the level may temporarily rise to a level slightly higher than the road surface level L0. The vehicle confirmation level L2 is set to a level that is slightly higher than the level of the signal caused by this shadow and as close as possible to the road surface level L0. When the output signal of the light receiving element increases and exceeds level L2, it is determined that this signal is caused by the vehicle and has exceeded road surface level L0. If the vehicle counters C1 and C2 continue counting and are not cleared forever, it is abnormal. This occurs when the reset signal is output earlier than the set signal, or when noise enters only on the set side, and this noise causes the vehicle counter C
1, this occurs when C2 starts counting. Vehicle counters C1 and C2 when counting the abnormal speed count number CM of the vehicle with the slowest expected speed
The count value of counters C1 and C2 is set to be slightly larger than the count number CM.
If it exceeds the limit, it is considered an abnormal situation and the measurement process is stopped as described later.

The memory 15 also has an area used as a collection flag F15 and an end confirmation time transfer flag F16. The collection flag F15 indicates that the measurement of the vehicle speed has been completed, and is turned on when the data abnormality flag F13 is off and the end confirmation time T1 of the reset signal has elapsed. When this flag F15 turns on,
The CPU 12 reads the speed data stored in the speed data area of the memory 15. CPU1
When the acquisition of speed data in step 2 is completed, this flag F15 is turned off. The end confirmation time transfer flag F16 indicates the end confirmation time T1 of the reset signal.
It is turned off when the period has elapsed. The CPU 12 is
It has a function of determining the completion confirmation time T1 according to the captured speed data, and changes the completion confirmation time T1 for each vehicle speed measurement. When the end confirmation time T1 selected by the CPU 12 is transferred to the shared memory 15, this flag F16 is turned on. As the completion confirmation time T1, a short time is selected when the measured vehicle speed is fast, and a long time is selected when the measured vehicle speed is slow.

Furthermore, the memory 15 includes vehicle counters C1 and C.
There are provided a speed data area for transferring two contents and storing speed data, and a pattern storage area for storing changes in the waveform of the reset signal. The data in this pattern storage area is used in various waveform pattern processing.

FIG. 6 shows the procedure of waveform analysis processing of the set signal by the CPU 11. This process takes 4.8mS
executed every time. First, the AD-converted current data Dt is read, and the preprocessed data D0 is subtracted from the current data Dt to obtain the deviation Δω (step 21). Then, the absolute value of this deviation Δω is compared with the reference amount ω0 to determine whether the change in the set signal is increasing, decreasing, or balanced (step 2).
2) If it is an increase or a decrease, the set signal temporary termination flag F2 is turned off (step 23). This flag F2 is always off when the set signal is increasing or decreasing, and is turned off if it was on when the signal moves from equilibrium to increasing or decreasing.

Next, it is determined whether the deviation Δω is increasing or decreasing by checking whether it is positive or negative (step 24), and if it is increasing, it is checked whether the current data Dt is equal to or higher than the cutting level L1 (step 25). If the current data Dt is equal to or higher than the cutting level L1, it is checked whether the recollection flag F6 is on (step 26). If the re-collection flag F6 is off, it is further checked whether the re-start flag F5 is on (step 27). This time, if the data Dt is above the cutting level L1 (YES in step 25) and both flags F6 and F5 are off, it will not exceed the cutting level L1 until the set signal rises and increases ( (see Figure 4b),
Turn on the restart flag F5 (step 28)
The vehicle speed counter C2 is cleared again (step 29). As a result, as will be described later, the re-vehicle speed counter C2 starts counting the detection time t. If NO in steps 24 and 25, YES in steps 26 and 27, and after processing in step 29, the process advances to step 30.

In step 30, it is determined whether the set signal flag F1 is off. Since the change state of the set signal is increasing or decreasing (in step 22)
YES), if the set signal flag F1 is off, it means that the set signal has started rising or falling. Therefore, to see whether it is rising or falling, we again judge whether it is increasing or decreasing (step 3).
1). If it decreases, it means a fall, so the set signal restart flag F4 is turned on (step 3).
2) (see Figures 4c and 4d). In the case of an increase, the process moves to step 33 without performing this process.

In this example, the road surface level L0 is updated every time a vehicle is detected. The road surface level L0 may be updated at any time as long as no vehicle is being detected, but here, it is when the vehicle detection starts, that is, when the set signal rises or falls after the road surface level L0 is in an equilibrium state. (YES in step 30). In step 33, the preprocessed data D0 at that time is updated as the road surface level L0.

Then, the set signal flag F1 is turned on (step 34), the set signal start flag F3 is turned on (step 35), and the vehicle speed counter C1 is cleared in order to measure the detection time t (step 36). This starts the time counting operation of the counter C1 as described later. Furthermore, the change pattern (increase or decrease) at the start of the set signal is stored (step 37), and the preprocessed data is updated with the current data Dt as the preprocessed data D0 (step 38), and the process is completed.

If the set signal flag F1 is already on (NO in step 30), check whether it increases or decreases (step 40).
As shown in the waveforms of FIGS. 4d and 4g, there are cases where the road surface level L0 is crossed, so to check this, it is checked whether the change pattern at the start is decreasing (step 41). If the pattern at the start is decreasing, it is considered that at the start, the signal components A and B due to shadows were falling from the road surface level L0, and then increased (YES at step 40), so the signal level is Vehicle confirmation level L
In order to check whether it exceeds 2, the road surface level L0 is subtracted from the current data Dt to find the deviation Δω1 from the road surface level L0 (step 42).
Then, this deviation Δω1 is compared with the confirmation level L2 (step 43), and the deviation Δω1 is found to be at the level L2.
If it is 2 or more, it is assumed that the set signal exceeds the road surface level L0 and is a signal from the vehicle, and the set signal start flag F3 is turned on (step 4).
4) Turn on the road crossing flag F7 (step 45), clear the vehicle speed counter C1, and start counting the detection time t (step 46).
After this and in the case of NO at each of steps 40, 41, and 43, the process moves to step 38. When the set signal starts rising or falling from the road surface level L0 (step 36), the counter C1
and is cleared when the set signal crosses the road surface level L0 (step 46).

If equilibrium is found in step 22, the process moves to step 47. As described above, it may be determined whether the pattern is a balanced pattern for each sampling period, or it may be determined whether the pattern is a balanced pattern in a time period of a prescribed period. If the prescribed period is used as a reference, the process moves to step 47 if equilibrium is established for each period. In step 47, it is checked whether the set signal temporary end flag F2 is on. If this flag F2 is off, the set signal is being detected and the fourth
As shown in figure f, this is an equilibrium state at the peak level or an equilibrium state at the road surface level L0 where no vehicle is detected. Therefore, it is checked whether the set signal flag F1 is on (step 48). If this flag F1 is on, the road surface level is in an equilibrium state of L0, so the process proceeds to step 38 and the current data Dt
The process is completed with the preprocessed data D0 as the preprocessed data D0 (step 38).

When the set signal flag F1 is on, either the peak level is in an equilibrium state, or the moment it falls and has just reached the road surface level L0 and shifts to an equilibrium state. Therefore, this time the data Dt
is compared with the road surface discrimination level L3 (step 4).
9). If the data Dt is level L3 or higher this time, the process moves to step 38. This time data Dt is level L3
If it is less than 1, the road surface level L0 has just been reached, so the set signal temporary end flag F2 is turned on (step 50), and after the end, the time counter C3 is set.
is cleared to prepare for the counter C3 to start measuring the elapsed time after completion (step 50). The process then proceeds to step 38.

If the set signal temporary end flag F2 is on (YES in step 47), the contents of the after-end time counter C3 are incremented by 1 to measure the time (step 52), and the contents of this counter C3 and the end confirmation time T1 are added. (Step 53). If the content of counter C3 is less than time T1, step 3
8, if the contents of the counter C3 have reached the time T1, the counter C3 is cleared (step 54), the set signal flag F1 is turned off (step 55), and the set signal temporary end flag F2 is turned off. (step 56), and the process proceeds to step 38.

FIG. 7 shows the waveform analysis processing procedure of the reset signal by the CPU 11. This process is also executed every 4.8mS. First, set signal start flag F3
If the flag F3 is on, the vehicle speed counter C1 is incremented by 1 and the vehicle speed (detection time t) is counted (step 61). Then, the contents of the vehicle speed counter C1 are compared with the abnormal speed count number CM (step 62). The contents of counter C1 are
If it is CM or higher, it is judged as abnormal data (4th e
(see figure). The set signal start flag F3 is turned on when the set signal rises or falls and when the set signal crosses the road surface level L0. Further, the set signal restart flag F4 is turned on when the set signal falls from the road surface level L0. Then, when these flags F3 and F4 are turned on, the counter C1 is cleared and speed measurement starts. In the case of abnormal data, the set signal start flag F3 and the set signal restart flag F4 are turned off (steps 63, 64) and the vehicle counter C1 is cleared (step 65) in order to stop the speed measurement. It is also preferable to detect the width of the reset signal to determine whether it is abnormal.

Next, it is checked whether the re-start flag F5 is on (step 66), and if this flag F5 is on, the content of the re-vehicle speed counter C2 is incremented by 1 to count the vehicle speed (detection time t) (step 6).
7). Then, as in step 62, the contents of the vehicle speed counter C2 are changed to the abnormal speed count.
If it is more than CM (YES in step 68), turn off the restart flag F5 (step 69),
The vehicle speed counter C2 is cleared again (step 70).

After the above vehicle speed counting process, the current data
The preprocessed data D0 is subtracted from Dt to obtain the deviation Δω (step 71), and the absolute value of this deviation Δω is compared with the reference amount ω0 (step 72). Deviation Δ
If the absolute value of ω is greater than or equal to the reference amount ω0, it means an increase or a decrease, so the reset signal temporary end flag F1 is set.
2 is turned off (step 73), and it is determined whether there is an increase or decrease (step 74). If it is an increase, it is further checked whether the current data Dt has reached the cutting level L1 (step 75), and if so, it is checked whether the re-start flag F5 is on (step 76). If the current data Dt is higher than the cutting level L1 and the repeat start flag F5 is on, the reset signal has reached the cutting level L1 at this time, so the repeat start flag F5 is set in order to finish counting the vehicle speed. (step 7)
7) Turn on the recollection flag F6 (step 78) (see Figure 4b). Then, the contents of the vehicle speed counter C2 at this time are transferred to the speed data area of the memory 15 (step 79). If NO in any of steps 74-76, the process immediately moves to step 80.

At step 80, the reset signal flag F11
Check if is off. Since the reset signal is in an increasing or decreasing state, if the reset signal flag F11 is off, it means that the reset signal is rising or falling for the first time from the road surface level L0. Therefore, the reset signal flag F11 and the reset signal start flag F14 are turned on (steps 81 and 82), and the preprocessed data D0 at that time is stored as the road surface level L0 (step 8).
3). Next, it is determined whether there is an increase or not to see whether it is rising or falling (step 84). If it increases, it is a rising trend. In the case of an increase, if the set signal start flag F3 is already on, the vehicle speed can be measured (as shown in Fig. 4a), and if the set signal start flag F3 is off, it is abnormal (see Fig. 4e).
figure). To confirm this, the state of the set signal start flag F3 is checked (step 85), and if this flag F3 is on, it is determined to be normal. Since the detection time t has ended, the set signal start flag F3 is turned off (step 86), and just to be sure, the set signal restart flag F4 and the road crossing flag F7 are turned off (steps 87 and 8).
8) The contents of the vehicle speed counter C1 are stored in the memory 15.
(Step 8)
9). Then, the reset signal start flag F14 is turned off (step 90), the waveform change is stored in the pattern storage area of the memory 15 as basic data for waveform processing (step 91), and the preprocessed data is stored using the current data Dt. D0 is updated (step 92) and the process ends. If the set signal start flag F3 is off in step 85, it means that there is an abnormality, so the data abnormality flag F13 is turned on (step 93) (see Figure 4e), and the counter C1 is turned on.
The process moves to step 90 without transferring the contents.

In the case of a decrease in step 84, there is a signal component due to shadows, as shown in FIGS. 4c, 4d, and 4g. For such a signal, first check whether the set signal restart flag F4 is on (step 94), and if it is off, check whether the set signal start flag F3 is on (step 85). If F3 is also off, data abnormality flag F13 is turned on (step 93).
(See Figure 4d). In this case as well, since the process of step 89 is not performed, the contents of counter C1 are not transferred. If the set signal restart flag F4 is on, it is checked whether the road crossing flag F7 is on (step 95). By this flag F7, the 4th c
A distinction is made between the signals in Fig. 4 and Fig. 4g. If the road crossing flag F7 is off (Fig. 4c), the state of the reset signal start flag F14 is checked (step 96), and if this flag F14 is on, the process moves to step 85 and the set signal start flag F3 is set. Check the condition. If flag F3 is on, flags F3, F4, and F7 are turned off (steps 86 to 88), and the contents of counter C1 are temporarily transferred to the speed data area of memory 15. The contents of the counter C1 transferred in this case are the time from the falling edge of the set signal to the falling edge of the reset signal, but this content will later be changed from the time when the set signal exceeds the road surface level L0 to when the reset signal reaches the road surface level. It is rewritten by the time (detection time t) until the time when level L0 is exceeded. If the road surface crossing flag F7 is on (YES in step 95) (Figure 4g), the set signal has already crossed the road surface level L0 and the detection time t is being measured, so the processing in steps 86 to 89 is performed. Proceed to step 90 without doing anything.

If the reset signal flag F11 is already on in step 80, the reset signal has already risen or fallen and continues. Therefore, it is checked whether it is in an increasing state or a decreasing state depending on the sign or negative of the deviation Δω (step 97), and if it is an increase, in order to check whether it has crossed the road surface level L0, the current data Dt and the road surface level L0 are The difference Δω1 is determined (step 98), and it is determined whether this difference Δω1 is equal to or higher than the vehicle confirmation level L2 (step 99).
If the difference Δω1 is equal to or higher than the level L2, it is further checked whether the set signal start flag F3 is on (step 100), and if this flag F3 is on, the data abnormality flag F13 is turned off (step 101) (Fig. 4d). ), proceed to step 86.
Through the processing from steps 86 to 89, each of the flags F3, F4, and F7 is turned off, and the detection time t (content of the counter C1) that has been measured since the time when the set signal exceeds the road surface level L0 is stored in the memory 1.
5 speed data area (4c)
(see Figures 4d and 4g). Step 9
If NO at 7, 99 and 100, the process moves to step 91.

In the case of an equilibrium state (NO in step 72), first check whether the reset signal temporary end flag F12 is on (step 102), and then set this flag F1.
2 is off, the reset signal flag F11
Check whether it is on (step 103). If this flag F11 is off, it means that the road surface is being detected, and the process immediately moves to step 91. If the reset signal flag F11 is on, there is a possibility that the road surface level L0 has just been reached and equilibrium has been achieved. Therefore, the current data Dt is compared with the road surface identification level L3 (step 104), and the current data Dt is at the level L3. If it is less than that, it is assumed that the road surface level has returned to L0, the reset signal temporary end flag F12 is turned on (step 105), and the counter C3 is cleared to measure the time after the reset signal is finished (step 10).
6), proceed to step 91. At step 104
If YES, proceed to step 9 as the equilibrium state at the peak level (see Figure 4f).
Move to 1.

If the reset signal temporary end flag F12 is on (YES in step 102), after the end, the contents of the time counter C3 are incremented by 1 to measure the time (step 107), and the contents of the counter C3 reach the end confirmation time T1. Check if it was done (Step 10)
8). If the end confirmation time T1 has not been reached, the process moves to step 91. When this time T1 is reached, the counter C3 is cleared (step 109), the flags F11 and F12 are turned off (steps 110 and 111), and the end confirmation time transfer flag F
16 is turned off (step 112). and,
It is checked whether the data abnormality flag F13 is on (step 113). If this flag F13 is on, the process moves to step 117, where the data abnormality flag F13 is turned off, and the process moves to step 91. If the data abnormality flag F13 is off, it means that the data is normal, so next it is checked whether the recollection flag F6 is on (step 114). When this flag F6 is on, the speed is measured based on the cutting level L1. If the recollection flag F6 is on, if necessary, the necessary processing is performed on the data based on the cutting level L1, and then the flag F6 is turned off (step 115). Then, the collection flag F15 is turned on (step 116), and the process moves to step 91. Even if the answer in step 114 is NO, the collection flag F15 is turned on (step 11).
6), proceed to step 91.

CPU12 collects the collection flag F15 every 19.2mS.
If the flag F15 is on, the measured detection time data is read from the speed data area of the memory 15 and necessary processing is performed, such as calculating the vehicle speed and the degree of congestion. When the CPU 12 takes in the detection time data from the memory 15, it turns off the collection flag F15. Further, when the completion confirmation time transfer flag F16 is turned off, the CPU 12 transfers the completion confirmation time already calculated based on the traveling speed of the preceding vehicle to the memory 15, and changes this time. After this, the flag 16 is turned on.

Therefore, FIGS. 4a, 4c, and 4
If the rising or falling edge of the set signal is earlier than the rising edge or falling edge of the set signal, as shown in Figure 4e, the vehicle speed can be measured normally, and as shown in Figure 4e, the vehicle speed can be measured normally. is earlier than the rising edge of the set signal, or the 4th d
As shown in the figure, if there is a shadow component and the fall of the reset signal is earlier than the fall of the set signal, the detection time is not measured. However, as shown in Fig. 4d, although the output order of the set signal and reset signal is reversed for the shadow component, if these signals are normal when they cross the road surface level in an increasing state, then detection is possible. It is possible to time the vehicle and measure the speed of the vehicle.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the installation state of the camera of the traffic flow measurement device, Fig. 2 is an enlarged view of the detection point, Fig. 3 is a configuration and block diagram showing the inside of the camera and the processing device, and Fig. 4 is the video image. A time chart showing the signal waveform and the status of each flag, Fig. 5 is an explanatory diagram showing waveform pattern detection, Fig. 6 is a flow chart showing the set signal processing procedure, and Fig. 7 is the reset signal processing procedure. This is a flow chart showing the following. P, P1 to P6...detection point, d _S 1 to d _R 6...
...Light receiving element, S...Set area, R...Reset area, L0...Road surface level, t...Detection time, F3
...Set signal start flag.

Claims (1)

[Scope of Claims] 1. A light-receiving element dS, which outputs video signals of a vehicle passing through a set area S and a reset area R, which are set at a required distance l from a vehicle speed detection point P, as a set signal and a reset signal, respectively. dR, means 8 for sampling each of the set signal and the reset signal at a predetermined period; means for determining the deviation Δω between the current sampling value Dt and the previous sampling value Do for each of the set signal and the reset signal; For each of the signals, the deviation Δω is compared with a predetermined reference value ω0, and if the absolute value of the deviation is larger than the predetermined reference value, it is determined that the signal is in an increasing state or a decreasing state,
Means F1 and F11 for storing this determination result determine that the rise or rise of the set signal and reset signal from the road surface level is determined based on the fact that the above determination is not stored. For each of the set signal and reset signal, the deviation Δω1 between the current sampling value Dt and the road surface level L0 is predetermined. means for detecting that the road surface level has been exceeded based on confirmation level L2 or higher; a timer that starts counting from zero upon detection of a rise or fall of the set signal from the road surface level or a detection that the road surface level has been exceeded; and a reset signal. If there is a memory of detecting the rising edge of the set signal when the rising edge of the reset signal is detected, if there is a memory of detecting the falling edge of the set signal when the falling edge of the reset signal is detected, and there is no memory of crossing the road surface,
Or, if there is a memory of the reset signal crossing the road surface detection when the reset signal crossing the road surface is detected, means for calculating the vehicle speed based on the time measured by the timer and the above required distance at that time. Speed measuring device.