FI83822C - Procedure and apparatus for observing traffic conditions - Google Patents

Description

1 83822

METHOD AND APPARATUS FOR DETECTING TRAFFIC CONDITIONS

The invention relates to a method 5 for detecting traffic conditions as defined in the preamble of the first method claim.

The invention also relates to a device according to the first device claim for detecting traffic conditions.

Road traffic calculation systems are already known, in which guide loops are installed on the road, by means of which vehicles passing over can be detected on the basis of inductance changes. Such an arrangement allows traffic counting to be performed, but not the classification of vehicles moving on the road. In addition, the installation of such a system requires that the road surface be broken in order to install the wiring harnesses. Wiring loops are also exposed to vibration, wear and frost damage at northern latitudes.

The object of the present invention is to provide 20 new methods and devices for detecting traffic conditions, by means of which road traffic can be better monitored as well as e.g. the condition of the road surface. With respect to the features of the method according to the invention, reference is made to the first method requirement and with regard to the features of the device according to the invention, reference is made to the first device requirement.

In the method according to the invention for detecting traffic conditions, the conditions prevailing on the road are detected by means of optical radiation so that a radiation beam is formed from the optical radiation; the radiation beam is directed at the road surface and placed at an oblique angle to the normal of the road surface; and the Siron radiation of the radiation beam is monitored. According to the invention, a plurality of linear radiation beams are formed; the radiation beams are arranged in parallel in the longitudinal direction and in a fan-like shape in the transverse direction; the radiation beams are applied to the road surface at a distance from each other so as to cover a measuring area of the desired width from the road surface; and on the basis of the scattered radiation, detecting at least vehicles and other elevational changes in the road surface and assessing the condition of the road surface. The method allows traffic to be monitored across the entire width of the road simultaneously.

In the method according to the invention, which is set out in claim 2, the entire measuring range 10 is examined in series in succession. In this way, the radiation coming to the detector is measured reliably and the parallel radiation beams do not interfere with each other. At the same time, data processing is simplified.

The method 15 set out in claim 3 makes it possible to monitor or assess the condition of the road surface. Depending on whether the road surface is dry, wet, icy or snowy, the road surface reflects radiation in different ways and this can be used to assess the condition of the road surface and e.g. warn 20 road users of dangerous weather if necessary.

According to the method set forth in claim 4, road traffic conditions can be observed at two different locations on the road at a predetermined distance from each other. With this method, e.g. determine the speed and direction of 25 vehicles.

The device according to the invention for detecting traffic conditions comprises a transmitter part and a detector part, the transmitter part having an optical radiation source and a lens arrangement by means of which a radiation beam is formed from the radiation provided by the radiation source, and the radiation beam is directed towards the road surface at a predetermined oblique angle to the normal; and wherein the detector portion includes a lens and detector and a data processing unit such as a microcomputer. According to the invention, the transmitter part comprises a plurality of optical radiation transmitters formed by radiation sources and 3 83822 lens arrangements of cylindrical lenses, which transmitters are arranged in the body in a shape corresponding to a circular arc at a distance from each other so that the radiation beams can be fan-directed cover the desired measuring range from the road surface and in which at least vehicles and other height changes on the road surface and the condition of the road surface can be detected by the intensity and / or location of the radiation scattered from the road surface and / or the vehicle.

Claim 6 discloses a preferred device for carrying out the method disclosed in claim 2.

A preferred embodiment of the invention is set out in claim 7, in which a separate radiation source is provided in the device, by means of which, together with the detector, the presence of fog, in particular in the vicinity of the road surface, can be detected.

Claim 8 discloses a preferred device for carrying out the method disclosed in claim 4.

The advantages of the method and device according to the invention can be stated as follows. The method can be applied without breaking the road surface or roadway 25 in any way. The device is installed above the road surface at a sufficient distance from the road surface and all observations are made by optical radiation. The method and device are used to determine the lengths, heights and, if necessary, speeds of vehicles moving on the road, as well as the condition of the road surface.

The invention will now be described in detail with reference to the accompanying drawings, in which Figure 1a schematically shows a device according to the invention; and Figure Ib is a top view of the road surface from the perspective of the corn portion of the device il-35; and an enlarged view of the device; Figure 2 shows another device according to the invention; Figure 3 shows a schematic view of the transmitter part; Figure 4 shows the structure of the device in block diagram form.

The device according to the invention in Fig. 1a 5 comprises a transmitter part 1 and a detector part 2, which are spaced dx apart. The transmitter part 1 has an infrared or IR radiation source 3, preferably an IR LED or an IR semiconductor laser, and a cylinder lens 4. By means of the cylinder lens 4, a radiation beam 5 is formed from the radiation as shown in Figure IB. The linear radiation beam 5 is directed towards the carriageway so that the longitudinal axis 5a of its cross section preferably coincides at least approximately with the longitudinal direction B-B of the road T and is at a predetermined oblique angle α to the normal N of the carriageway.

The detector part 2 comprises a lens 6 and a detector 7. The detector 7 is preferably a CCD line detector or a position-sensitive photodiode. The field of view 20a of the objective is in principle a conical area in front of the detector part, from which area the whole area or a suitably delimited part 20 in Fig. Ib falls on a part of the detector. A line 5b or 5c is formed from the line-shaped radiation beam 5 hitting the vehicle A or the road surface T, 25, respectively, by means of an objective 6 on the surface of the detector 7. The position of the radiation beam 5 in Figures 5b, 5c depends on the distance of the surface to be measured, such as vehicle A or road surface T, from the lens 6. When the location of the radiation beam 5, 5c is detected by the detector 7, vehicle A can be detected without moving the beam image. By means of a suitable data processing unit 8, such as a microcomputer, the necessary calculations can be performed, the basics of which are set out below.

The position of the center 5d of the radiation beam 5 with the detector 7 as a function of the distance 5,838,222 between the surface A1 of the vehicle A and the objective 6 is shown in Fig. 1a. The radiation beam 5 and its optical axis li are at an oblique angle α with respect to the normal N of the roadway. The optical axis Io of the detector is also perpendicular to the road surface.

5 The focal length of the objective lens 6 is f. The center 5d of the radiation beam 5 on the road surface T is the distance ha. from the normal path N of the carriageway conceived at the transmitter section. The center of the beam 5d 'on the surface AI of the vehicle A is in turn a distance ha from the normal N. The image of the center of the beam on the surface of the beam 10 with the detector is the distance ha.' from the optical axis Ie of the detector and the image of the center of the radiation beam hitting the surface A1 of the vehicle A at the detector is at a distance ha 'from the optical axis Io of the detector as shown in Figure le. The transmitter part 1 and the detector part 2 are located at a distance Si above the road surface T.

The position of the center 5d hitting the road surface T of the radiation beam 5 on the surface of the detector is now obtained ni f / k j i _ fhi, fdÄ (1) h, '= - s; (h.-d.) - - · The position of the center point 5a1 hitting the surface AI of the radiation beam 5 on the surface A of the vehicle A is obtained on the surface of the detector: (2) h. · - - f; (h.-d.) - - g * + fä ».

When we place ha -2 --— 4 'n ^ n we get (* aan O) - g (sg * - »O - - g1 + g1 ·

In formulas 1, 2 and 3 it is assumed that sx »f and sa» f, i.e. when the focal length f of the lens 6 is much smaller than the distance sa of the surface A of the vehicle A or road T from the lens 6, the change in the position of the beam image by the detector 5 depends only on the vehicle A you objective 6.

As can be seen from the above, the position of the center 5d of the radiation beam 5 on the detector 7 is proportional to the height A1 of the vehicle A. It is clear that 6 83822 other elevational changes in the road surface can also be observed. For example, if it is winter time and the road surface is snowy and the position of the radiation beam on the detector has moved for a relatively long time from the location corresponding to the road surface 5, snow cinema has apparently accumulated on the road.

The condition of the road surface can also be monitored and observed using the device described above. The intensity of radiation scattered or reflected from the road surface 10 depends on the characteristics of the road surface. In order to assess the condition of the road surface, it is advantageous to divide the road surfaces into four categories, for example: 1. the road surface is dry, 2. the road surface is wet, 3. the road surface is icy or covered with black ice, and 4. the road surface is snowy. This can be realized by comparing the intensity of the transmitted radiation beam 5 and the intensity of the radiation scattered from the road surface, and on this basis the condition of the road surface is evaluated.

The linear radiation beam is directed above 20 towards the road surface so that the long axis 5a of its cross section is in the longitudinal direction of the road and generally in the direction of traffic. However, it is possible to place the device above the road so that the long axis 5a of the radiation beam is at an oblique angle to the longitudinal direction 25 of the road. In this case, however, the measurement sensitivity is lost.

A preferred embodiment of the device according to the invention is shown in Figure 2. The transmitter part 1 and the detector part 2 of the device and the associated data processing part 8 are fixed to a suitable support 9 at the desired height Si above the road surface T. The transmitter part 1 and the detector part 2 are spaced apart from each other, which distance is preferably 0.5 to 1.0 m. The transmitter part 1 and the detector part 2 are mounted on a support 9 so that their optical axes li and Io are perpendicular to the road .... against the surface T.

The transmitter part 1 of the device shown in Fig. 2 is 7 83822 shown in principle enlarged in Fig. 3. The transmitter part 1 comprises a number of infrared transmitters 10, of which there are ten in this embodiment of the transmitter part. The infrared or IR transmitters 10 are formed by 5 IR radiation sources 3, such as IR LEDs, and cylinder lenses 4 arranged in the body 11 of the transmitter part. The IR transmitters 10 are arranged in the body 11 of the transmitter part so as to be located on the arc of the circle 11a at a distance apart. In this case, the IR transmitters 10 are further arranged so that the optical axes Ixo of their radiating beams 50, 51, 52, 59,

In, ..., I i «intersect each other at the center O of the circular arc 11a and symmetrically with respect to the central axis of the transmitter part 1, i.e. the optical axis li.

The radiation beam 50,51,52, .., 59 from each IR transmitter 10 is linear. The opening angle β of the radiation beam is preferably of the order of 2-4 * with respect to the transverse direction of the cylinder lens 4. In the longitudinal direction of the cylinder lens, the opening angle corresponds to or is somewhat limited by the opening angle of the IR radiation source 20. It can be of the order of 10-25 '.

The body 11 of the transmitter part is located inside the protective housing 12. The front plate 12a of the protective housing is arranged at a distance from the IR transmitters 10 in which the optical axes of the radiation beams intersect each other, i.e. in the vicinity of the center 0 of the circular arc 11a. The front plate 12a has a slot or opening 13 arranged at this center O, through which the radiation beams pass out of the transmitter part 1. A filter 30 or a protective glass can be arranged in the slot 13 to delimit a certain radiation frequency range or generally prevent dust from entering the housing 12.

From the transmitter part 1, the radiation beams 50, 51, 52, ..., 59 are fan-directed to the road surface T, 35 as shown in Fig. 2. In this case, they cover a certain desired measuring range D in the transverse direction of the road. The device can be installed, for example, at a height of Si = 8 - 12 m above the surface of road 8 83822. In this case, the width D of the measuring range is of the order of 10 to 15 m. The radiation beams 50, 51, 52, ..., 59 meet at a distance from the road surface of the order of 1 to 2 m and symmetrically to the optical axis Ia of the transmitter part 1. both sides.

The detector part 2 is formed of a CCD line camera comprising a lens 6 and a CCD line detector 7. Instead of said detector, another suitable one-dimensional detector sensitive to the radiation used can be used. The detector part 2 preferably also includes a data processing unit 8 such as a microcomputer. In addition, the objective 6 of the detector part 2 is preferably provided with a filter 14, by means of which the stray light entering the detector is reduced and in this case the light visible is prevented from entering the detector.

The field of view 20 of the detector 2 is set so as to cover the measuring range D.

By means of the data processing unit 8, the detector elements 7a of the detector 7, which are in succession in one direction, are read and the intensity and distribution of the received radiation in the longitudinal direction of the line detector are registered. The measurement data are stored in the memory 16 of the data processing unit (see Figure 5).

The operation of the transmitter part 1 is also controlled by means of the data processing unit 8. Each IR transmitter 10 of the transmitter section is connected to a switching section 15. The switching section 15 comprises a number of switches, preferably electronic switches, by means of which each IR-led 3 can be connected to a power supply U. The data processing unit 30 8 is connected to the switching section 15. any IR-led 3 to operate by acting on the corresponding switch in the switch part 15.

The device according to the invention in Figures 2, 3 and 4 operates in principle as follows. By means of the data processing unit 35, by acting on the switching part 15, the IR transmitters 10 of the transmitter part 1 are made to operate one by one. In this case, one beam of radiation 50, 51, 52, 9 83822 ..., 59 at a time is directed from the transmitter part 1 to the road surface T.

If a vehicle with a height A1 or A2 moves in the detection area (Fig. 3), the position of the radiation beam 50 on the road surface hi has moved towards and is at a distance from the optical axis Ix of the transmitter part 15. or haa. This is detected by the detector part 2 as a similar transverse displacement on the surface of the detector 7, i.e. ha. ' and ha 'or ha' ', respectively, which can be placed in the above formulas 1 and 3. The data processing unit 8 10 can then be used to calculate e.g. vehicle height Aa. or Aa or Si - sa.

The measuring area D is passed through one beam 50,51, 52, ..., 59 at a time and the position of the beam on the road and / or vehicle surface 15 in the measuring area is measured by the detector part 2 and stored in the memory 16 of the data processing unit 8. When all beam locations and stored in memory 16, they are compared to the locations of the radiation beams in the memory on the road T surface. Deviations from the surface corresponding to the surface 20, i.e. the shark or the shark, respectively, indicate the presence of the vehicle or the like in question. at the radiation beam. From the magnitude of the deviation, the height of the vehicle at this beam can be determined. Since the direction and position of each radiation beam 25 with respect to the optical axis I® of the detector part 2 can be determined, the width and position of the vehicle on the roadway can be determined from known changes in the positions of the radiation beams from the road surface on the detector 7.

The condition of the road surface can be monitored with the device described in brochure 30 above as follows. The intensities of the radiation beams transmitted successively by the IR transmitters 10 of the transmitter section 1 in succession are adjusted on the basis of the reflection characteristics of the road surface T so that the signal 35 from the road surface scattered radiation to the detector section 2 remains strong enough to be clearly detected. The data processing unit 8 can be used, for example, to control the power supplied to the IR transmitters 10 via the switching section 15 by 83822 by a separate control unit 17. These set control values are stored e.g. in the memory 16 of the data processing unit 8. From the transmitter section 1 to the road surface T .., 59 meet 5 at different but defined angles of the road surface and likewise the angle of attack with respect to the optical axis le of the detector part 2 varies.

As the characteristics of the road surface change, it is differently scattered by radiation, which is detected by the detector-10 part 2. Once the reference values for each beam of radiation under certain road surface conditions are stored in the memory 16, changes in the road surface state can be detected immediately. For example, reference values for four road surface classes can be stored in memory, as already stated above, and the measured values can be compared with these reference values and the state of the road surface can be deduced.

At least two devices according to the invention can be arranged in connection with the road in the direction of the road 20 at a desired distance from each other. The data processing units 8 of these devices can be connected to each other. With the help of two devices, the speed and direction of the vehicles can be determined. By means of the data processing units 8: it is possible to check whether there is a vehicle for both devices. When a vehicle is detected at another device, the data processing unit 8 measures the time that elapses from this moment until the other device also detects the same vehicle. The direction of the vehicle can be deduced from which device first detects the vehicle. Such devices 30 can be used for monitoring and counting traffic in different directions as well as for speed monitoring.

An additional IR transmitter 10a may be added to the transmitter part 1 of the device, which includes an IR radiation source 3a, 35 preferably an IR LED or an IR semiconductor laser, and a lens 4a, preferably a cylinder lens, as shown in Fig. 3. The optical axis Iai 11 83822 of this IR radiation source 3a preferably forms an angle δ of about 30 'or more with the optical axis I »of the detector 2 (see Fig. 2). By means of the radiation source 3a and the detector 2, the presence of fog above the roadway can be detected. The radiation beam 60 of the beam source 3a passes through the field of view 20 of the detector 2 and, if fog occurs, causes the radiation beam 60 to scatter the radiation detected by the detector 2. The IR radiation source 3a is used in the same way as the other radiation sources 3 in the detector 1 and can be identical.

Other IR transmitters 10 of the transmitter part 1 and the radiation beams 50, 51, 52, ..., 59 formed by them can also be used to detect fog. For example, the distribution of radiation scattered from 15 radiation beams 50 can be examined at successive elements 7a of the detector part 2 (see .picture 4). From this radiation intensity distribution provided by the various detector elements, the known road surface scattering point 20 and the areas immediately above the road surface can be delimited. If the intensity of the radiation scattered from other areas exceeds a certain limit, it can be concluded from this that fog is present.

One or more infrared radiation sources are described above for use in the device according to the invention. However, it is clear that the frequency range of the radiation used can generally be in the frequency range of optical radiation, i.e. in the wavelength range of visible light, as well as in the wavelength range of infrared radiation. However, the use of infrared radiation is advantageous because during the day the ambient light interferes with the measurement.

The invention has been described above with reference to its preferred application examples, but it is clear that the invention can be applied in many different ways within the scope of the inventive idea defined by the appended claims.

Claims (8)

1. A method of observing traffic conditions, wherein a method of optical radiation is observed along the way of saving conditions such that 5. of the optical radiation a beam cone is formed (5); - the beam cone is directed towards the road surface and is installed in the ratio of the normal (N) to the road surface at an oblique angle (a)? - the scattering radiation from the beam source (5) is observed, characterized in that - a plurality of linear beam cones (50, 51, 52, 59) are formed; the road surface at a distance from each other such that they cover a desired wide measuring range (D) of the road surface (T); and - due to the scattering radiation, Atminstone vehicle (A) and other changes in height are observed in the road surface and the condition of the road surface is estimated. 2. A method according to claim 1, characterized in that - a beam cone (50, 51, 52, 59) sets the thread in operation; 25. the strength of the beam cone scattered from the road surface (T) or the vehicle (A) is measured and - the measured values are stored in the memory (16); - when all the beam cones have in turn been passed through and the measurements have been carried out, the measurement values are compared with the previously estimated corresponding scattering radiation values from the road surface and due to the horizontal deviations the occurrence of vehicles is determined. Method according to any of the preceding patent claims, characterized in that the strength of the emitted beam cone (5; 50, 51, 52, 59) and the strength of the scattering radiation are compared between themselves, due to the comparison of the state of the road surface (T) and / or ie 83,822 weather conditions above the road surface are estimated. Method according to any of the preceding claims, characterized in that, in the aid of one or more linear shaped cones (5; 50, 51, 52, 59), the road surface is observed at two points in the longitudinal direction of the road at a certain distance from each other. . 5. Device for observing traffic conditions, to which device a transmitter part (1) and a detector part (2) belong, in which transmitter part (1) there is a beam source (3) transmitting optical radiation and a lens system (4) , by means of which the radiation transmitted from the beam source is formed into a beam cone (5), and the beam cone (5) is directed towards the road surface so that, in its longitudinal direction relative to the road rudder (N), it is at a predetermined oblique angle (a); and in which the detector portion (2) contains an objective (6) and a detector (7) and a data processing portion (8), such as a microcomputer, characterized in that the transmitter portion (1) includes a plurality of optical radiation emitters (10), which have been formed by the radiation sources (3) and the lens systems of cylinder lenses (4), which transmitters (10) are adapted to a frame part (1 1) in a shape corresponding to a circle (11a) at a distance from each other such that the beam cones 25 (50, 51, 52, ..., 59) can be aligned with the spring surface (T) on the road surface and so as to cover the desired measuring area (D) of the road surface (T) and in which device the aid received by the detector (7) is received. The strength and / or position of the radiation scattered from the road surface (T) and / or the vehicle (A) at least vehicles and other height changes occurring in the road surface and the condition of the road surface can be observed. Device according to claim 5, characterized in that the transmitter part (1) includes a switching part (15) which is connected to each transmitter (10) which is controlled by the data processing unit (8), only one transmitter (10) eats the thread into operation and whose corresponding beam source beams (50, 51, 52, ..., 59) are emitted from the road surface or vehicle scattered radiation position and / or strength is measured by the detector portion ( 2) detector (7) and stored in memory (16), on the basis of which measurement values and by comparison with previous measurement values determine the traffic conditions on the way. Device according to any one of the preceding claims 6, 7 or 8, characterized in that in the transmitter part (1) of the device there is still a separate optical source (10a), which consists of a source of radiation (3a) and a lens, advantageously advantageously, a cylinder lens (4a) whose radiation source (10a) optical axis (Ia) and beam cone (60) forms a 30 * or greater angle (δ) with the optical axis (I0) of the detector portion (2) and with which radiation source (10a) and detector (7) detector (7) can be used to detect the presence of fog. Device according to any of the preceding claims 5, 6, or 7, characterized in that there are at least two devices, and they are arranged in connection with the road in the direction of the road at a certain definite distance from each other.