JP2005061972A - Vehicle speed measuring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly precisely measure the speed of a vehicle by a simple constitution. <P>SOLUTION: This vehicle speed measuring system 10 is provided with a first optical range finder 14a for measuring the distance to the vehicle 12 passing through a first location Xa of measurement, a second optical range finder 14b for measuring the distance to the same vehicle 12 passing through a second location Xb of measurement, and an arithmetic processing part 16 for computing the speed of the vehicle 12 on the basis of both the measurement execution timings of the first and second optical range finders 14a and 14b to the same vehicle 12 and the distance L between the first and second locations of measurement. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicle speed measurement system that measures the speed of a vehicle using an optical distance meter.

  As a vehicle speed measurement system, for example, a method using a photoelectric sensor as disclosed in Patent Document 1 is known. In this system, an optical path from the emitter to the light receiver (photoelectric sensor) is formed, and the passage of the vehicle is detected as being blocked. Then, this photoelectric sensor is installed in two locations along the moving direction of the vehicle, and the distance between the measurement positions of the two photoelectric sensors is divided by the difference in detection time between the photoelectric sensors, so that the vehicle speed Is measured.

JP 2000-206135 A

  However, the conventional photoelectric sensor cannot identify which point in the optical path the vehicle has passed. Therefore, when it is necessary to form an optical path across multiple lanes in order to perform speed measurement on a road with multiple lanes, in the case where the vehicle is running in parallel, the detection result of one vehicle is It cannot be denied that there is a possibility that the vehicle speed cannot be measured correctly because it is mistaken for the detection result. Therefore, conventionally, in order to exclude such cases from the target of speed measurement, an erroneous measurement prevention function is provided, a monitor is arranged, or an optical distance meter is provided for detecting such cases. Was. In addition, there is a problem that the measurement result of a vehicle that has traveled obliquely, such as changing lanes within the speed measurement section, is slightly lower than the actual speed.

  A vehicle speed measurement system according to the present invention is configured to measure a distance between a first optical rangefinder that measures a distance from a vehicle that passes through a first measurement position and a vehicle that passes through a second measurement position. Speed calculation for calculating the speed of the vehicle based on the optical distance meter of the first vehicle and the measurement execution timing of the first and second optical distance meters for the same vehicle and the distance between the first and second measurement positions A section.

  In the vehicle speed measurement system according to the present invention, it is preferable that the speed calculation unit further calculates the vehicle speed based on the distance measurement results of the first and second optical distance meters.

  In the vehicle speed measurement system according to the present invention, it is preferable that the first and second optical distance meters measure the distance from the vehicle from above.

  First, a first embodiment of the present invention will be described with reference to the drawings. 1 is a schematic configuration diagram of a main part of a vehicle speed measurement system 10 according to the present embodiment (a diagram in a case where speed measurement is performed on a vehicle 12 traveling on a road 18 having two unidirectional lanes). These are the figures which show typically an example of the emitted light and distance detection result in each optical distance meter 14a, 14b, and FIG. 3 is explanatory drawing which shows the movement distance when the vehicle 12 drive | works diagonally.

  The vehicle speed measurement system 10 includes a first optical distance meter 14a that measures a distance da from the vehicle 12 that passes through the first measurement position Xa, and a second measurement position Xb (= the road from the first measurement position Xa to the road). The second optical rangefinder 14b that measures the distance db to the vehicle 12 that passes through the vehicle 18 passing through a predetermined distance L along the line 18 and the measurement results of the first and second optical rangefinders 14a and 14b. And an arithmetic processing unit 16 that performs predetermined arithmetic processing such as speed calculation.

  The optical rangefinders (eg, laser rangefinders, infrared rangefinders, etc.) 14a, 14b are known devices. For example, the measurement target (in this case, the vehicle 12) is irradiated with a pulse beam, and based on the transmission / reception time difference. The distance to the measurement object is measured. In the example of FIG. 1, the optical distance meters 14 a and 14 b emit light (pulse beam) in a direction substantially transverse to the ground and perpendicular to the road 18. At this time, it is preferable to adjust the installation height, the emission direction, and the like so that the emitted light hits the tire of the vehicle 12, for example.

  Each optical distance meter 14a, 14b emits light at a predetermined timing (for example, every 5 ms) as shown in FIG. When the vehicle 12 passes through the measurement positions Xa and Xb, the light reflected by the vehicle 12 is detected, and the distances da and db are detected based on the reflected light at that time.

The arithmetic processing unit (for example, a computer or the like) 16 calculates the speed V1 of the vehicle 12 (the speed component of the vehicle 12 in the road extending direction (longitudinal direction)), for example, the following formula: T = | ta−tb |
V1 = L / T (1)
Calculated by Here, ta: timing (time) when the vehicle 12 (distance to) is measured at the first measurement position Xa, tb: timing when vehicle 12 (distance to the second measurement position Xb) is measured (time) Time).

  Here, the arithmetic processing unit 16 travels substantially straight along the road 18 when the moving distance of the vehicle 12 between the two measurement positions Xa and Xb is approximately the distance L, that is, the vehicle 12 does not change lanes. Only when this is the case, the velocity V1 of the equation (1) is validated. Therefore, prior to the calculation of the speed V1, the arithmetic processing unit 16 determines whether or not the moving direction of the vehicle 12 in this section is a direction along the road from the distance measurement results da and db of the optical distance meters 14a and 14b. Judging. Specifically, for example, the arithmetic processing unit 16 determines that the vehicle 12 is in the road 18 at the measurement positions Xa and Xb from the distance measurement results da and db by the first and second optical distance meters 14a and 14b. Which position Ya, Yb in the width direction (width direction position; Ya = da-Aa, Yb = db-Ab, where Aa, Ab: distance to the road edge on the near side. The road edge on the near side is Ya, Yb. = 0). Only when the difference between the width direction positions Ya and Yb at the two measurement positions Xa and Xb is within a predetermined range (that is, the width direction positions Ya and Yb are substantially the same at the two measurement positions Xa and Xb). The speed V1 of the vehicle 12 is calculated by (1). The arithmetic processing unit 16 determines whether or not the vehicle 12 is in the road 18 from the width direction positions Ya and Yb, and does not calculate the speed if the measurement is not performed correctly for some reason. I have to.

On the other hand, when the difference between the width direction positions Ya and Yb is not within a predetermined range, that is, when the vehicle 12 travels obliquely between the first and second measurement positions Xa and Xb as shown in FIG. The arithmetic processing unit 16 calculates the actual travel route Lr from the acquired width direction positions Ya and Yb and the distance L, and calculates the speed V2 of the vehicle 12 from the travel route Lr. In particular,
Lr = sqrt (L ² + | Ya−Yb | ² )
T = | ta−tb |
V2 = Lr / T (2)
And At this time, the speed component of the vehicle 12 in the road extending direction (longitudinal direction) is V1 (= L / T) in the equation (1), and the speed component V22 in the road transverse direction (width direction) is ,
V22 = | Ya−Yb | / T (21)
It is.

  According to the vehicle speed measurement system 10 according to the present embodiment, the optical distance meters 14a and 14b can detect the timing at which the vehicle 12 passes through the measurement positions Xa and Xb, and can grasp the movement path of the vehicle 12. it can. That is, it is simpler than the case where a photoelectric sensor for detecting the passage timing of each measurement position and an optical distance meter for grasping the movement path are separately provided as in the conventional technique. Speed measurement with high accuracy can be performed depending on the configuration. In addition, when using a photoelectric sensor as in the above prior art, it is necessary to form and adjust a reflecting mirror or the like to form an optical path from the emitter to the light receiver. In such cases, such trouble is not required. Although the case where the speed calculation formulas (1) and (2) are selectively used according to the width direction positions Ya and Yb has been described here, the speed V1 is always calculated using the formula (1) or the formula (2 ) May be used to calculate the speed V2.

  Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a schematic configuration diagram of a main part of the vehicle speed measurement system 30 according to the present embodiment (a plan view when speed measurement is performed on the vehicle 12 traveling on the road 18 having two unidirectional lanes). FIG. 5 is a conceptual diagram (side view seen in the extending direction of the road 18) of the measurement by the optical distance meters 34a and 34b at the measurement positions Xa and Xb. FIG. 5 is a diagram of the first measurement position Xa, but the second measurement position Xb has the same positional relationship.

  The vehicle speed measurement system 30 according to the present embodiment also calculates the speed of the vehicle 12 from the distance measurement results da and db of the optical distance meters 34a and 34b at the first and second measurement positions Xa and Xb. This point is the same as in the first embodiment.

  However, in the vehicle speed measurement system 30 according to the present embodiment, as shown in FIG. 5, the optical distance meters 34 a and 34 b do not project light in the horizontal direction, but above the vehicle 12 (preferably the vehicle Light is projected from a position sufficiently higher than the height (in this example, obliquely above), which is different from the first embodiment. In the vehicle speed measurement system 10 according to the first embodiment, each of the optical distance meters 14a and 14b emits light in the horizontal direction. Therefore, when two vehicles travel along a road in multiple lanes, the front side The light is reflected by the vehicle, and the speed of the vehicle on the far side (far side) cannot be measured. Therefore, in the present embodiment, light is applied to the vehicle from above, and the influence of the vehicle in front of the vehicle on the speed measurement on the far side is eliminated.

  In the present embodiment, the optical distance meters 34a and 34b transmit the emitted light at a predetermined cycle from the front end (θmin) to the front end (θmax) of the road 18 at each measurement position Xa and Xb. And the reflected light is detected at each emission angle θ (for example, a predetermined angle step). At this time, the optical distance meters 34a and 34b measure the distance to the road surface 18s of the road 18 when the vehicle 12 is not on the road 18, but when the vehicle 12 is on the road 18, that is, the vehicle. When 12 passes measurement positions Xa and Xb, distances da and db to the surface (surface that reflects light) of the vehicle 12 are measured. Therefore, the arithmetic processing unit 36 obtains the difference between the measured distances da and db detected at each emission angle θ and the measured distance in the absence of the vehicle 12, thereby obtaining the vehicle at each measured position Xa and Xb. The presence or absence of 12 can be determined. The optical distance meters 34a and 34b may have, for example, a swing mechanism driven by a motor or the like, or a swinging mirror such as a semiconductor galvanometer mirror is provided, and light from the light source is passed through the mirror. You may make it radiate | emit.

Further, the width direction positions Ya and Yb of the vehicle 12 at the respective measurement positions Xa and Xb can be grasped from the measured emission angle θ of the vehicle 12. That is, in the example of FIG. 5, when the vehicle 12 is detected with a relatively small exit angle, the vehicle 12 is positioned on the near side (side closer to the optical distance meters 34a and 34b), and conversely a relatively large exit angle. When the vehicle 12 is detected, the vehicle 12 is positioned on the far side (the side far from the optical distance meters 34a and 34b). And, between the emission angle θ and the width direction positions Ya and Yb, the following formula Ya = da · sin θ−Aa
Yb = db · sin θ−Ab (3)
Here, the relationship Aa, Ab: distance from the vertically lower position of each optical distance meter 34a, 34b to the road edge on the near side is established. The speed V1 or V2 of the vehicle 12 is calculated using the method (formula (1), formula (2), etc.) described in the first embodiment together with the formula (3).

  In the above embodiment, the optical distance meters 34a and 34b are installed above the lane. However, the present invention is not limited to this, and the same effect can be obtained by installing the optical distance meters 34a and 34b directly above the lane.

  As described above, even with the vehicle speed measurement system 30 according to the present embodiment, it is possible to perform highly accurate speed measurement with a simpler configuration as compared with the conventional technique. Furthermore, according to the present embodiment, even when a plurality of vehicles run in parallel, each vehicle can be captured regardless of the presence of other vehicles, and the speed thereof can be accurately calculated.

1 is a diagram (plan view) showing a schematic configuration of a main part of a vehicle speed measurement system according to a first embodiment of the present invention. It is a figure which shows typically an example of the emitted light and the distance detection result in the optical distance meter of the vehicle speed measurement system concerning embodiment of this invention. It is explanatory drawing which shows the movement distance when a vehicle drive | works diagonally. It is a figure (plan view) which shows schematic structure of the principal part of the vehicle speed measurement system concerning 2nd embodiment of this invention. It is a conceptual diagram (side view) of the measurement by the optical distance meter of the vehicle speed measurement system concerning 2nd embodiment of this invention.

Explanation of symbols

  10, 30 Vehicle speed measurement system, 12 vehicles, 14a, 14b, 34a, 34b Optical distance meter, 16, 36 arithmetic processing unit, 18 roads, 18s road surface.

Claims (3)

A first optical rangefinder for measuring a distance from a vehicle passing through a first measurement position;
A second optical rangefinder that measures the distance to the vehicle passing through the second measurement position;
A speed calculation unit that calculates the speed of the vehicle based on the measurement execution timing of the first and second optical distance meters for the same vehicle and the distance between the first and second measurement positions;
A vehicle speed measurement system comprising:   The vehicle speed measurement system according to claim 1, wherein the speed calculation unit further calculates a vehicle speed based on a distance measurement result of the first and second optical distance meters. The vehicle speed measurement system according to claim 1 or 2, wherein the first and second optical rangefinders measure a distance from the vehicle from above.

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