Classifications

• • G—PHYSICS
  • G07—CHECKING-DEVICES
  • G07B—TICKET-ISSUING APPARATUS; FARE-REGISTERING APPARATUS; FRANKING APPARATUS
  • G07B15/00—Arrangements or apparatus for collecting fares, tolls or entrance fees at one or more control points
  • G07B15/06—Arrangements for road pricing or congestion charging of vehicles or vehicle users, e.g. automatic toll systems
  • G07B15/063—Arrangements for road pricing or congestion charging of vehicles or vehicle users, e.g. automatic toll systems using wireless information transmission between the vehicle and a fixed station
• • G—PHYSICS
  • G08—SIGNALLING
  • G08G—TRAFFIC CONTROL SYSTEMS
  • G08G1/00—Traffic control systems for road vehicles
  • G08G1/01—Detecting movement of traffic to be counted or controlled
  • G08G1/015—Detecting movement of traffic to be counted or controlled with provision for distinguishing between two or more types of vehicles, e.g. between motor-cars and cycles
• • G—PHYSICS
  • G08—SIGNALLING
  • G08G—TRAFFIC CONTROL SYSTEMS
  • G08G1/00—Traffic control systems for road vehicles
  • G08G1/01—Detecting movement of traffic to be counted or controlled
  • G08G1/017—Detecting movement of traffic to be counted or controlled identifying vehicles
  • G08G1/0175—Detecting movement of traffic to be counted or controlled identifying vehicles by photographing vehicles, e.g. when violating traffic rules

Definitions

• the present invention relates to a device for the identification of a vehicle in a control station by means of image processing of some kind of image recording, preferably video recording is intended. Especially intended is the successive position identification of vehicles that pass a road toll facility or other control station.
• the free-flow system is based on the presumption that the vehicles are provided with an equipment by which a transmitter and receiver equipment in the road toll facility can cc ⁇ tunicate with the vehicle and carry out the registration of the toll fee either by drawing means from a prepaid balance in the vehicle equipment or by registering the identity of the vehicle for post-debiting or deduction from a special account.
• the vehicle driver assists in paying the fee in some other way, for example manually in a cash-desk. If however the driver attempts to pass the toll facility without paying the fee in any manner, it must be possible to perform a registration for post-debiting.
• Vehicles of many different types shall be tracked, for example motor cycles, lorries and trucks with trailers.
• the displacement can occur at varying speed and in a free roadway within the limits that the width of the road allows and the image of each vehicle is to be kept separate frcm irrelevant image elements such as shadows, reflections and also with changes in the mutual positions of the vehicles.
• a stereo recording is used to obtain greater certainty in the classi ⁇ fication, in that in addition to the contour of the vehicle, the position of certain portions of the vehicle in the direction of the cameras can also be read.
• the video recording is performed frcm above down at the roadway and thereby the external contour of the vehicle is caught in the horizontal plane up and at the same time its various height levels.
• a certain structuring is required of the object to be recorded.
• the mere contour can be used to determine the position and height profile of the vehicle in the image processing. This can cause some uncertainty in the position identification, particularly during unfavourable conditions such as heavy rain or snow or with trail shadows due to sun radiation at certain angles.
• the problem to be solved by the invention is that in position identi ⁇ fication and classification of the vehicles, means must be found to structure particularly big surfaces of similar colour. As mentioned, the solution to this problem has particularly great importance in the use of stereo recordings for the tracking of vehicles in motion and above all vehicles on a road in a control station.
• this problem is solved in that the area in which the position of the vehicle shall be indicated, is illuminated by a structured light.
• a device is provided to achieve such a light, so that a structuring of light that is clear to the apparatus can be obtained also in conditions with full sunlight and limited vision. This is done with the aid of several interacting factors: the concentration of the light spot-wise, concentration through illumination in short time intervals, so that a high concentration of light is obtained despite low average illumination, and a choice of a favourable light wavelength.
• Fig 1. a view in persp-ective of a road toll facility with an illumination device according to the invention
• Fig. 2 a schematic picture in a vertical plane of the road toll facility with the illumination device
• Fig. 3 a front view of the illumination device
• Fig. 4 a cross-section through the illumination device cut along the line IV-IV in Fig. 3;
• Fig. 5 two images beside each other representing the recording in the image plane of two video cameras representing a recording in the camera arrangement shown in Fig. 2.
• FIG. 1 an overview of a road toll facility 1 is shown by a roadway 2 with lanes 3 in which a number of vehicles 4 are driven and thereby passing the toll facility.
• this is equipped with wireless com ⁇ unication between the road toll facility and the vehicles.
• radio communication units 7 there are arranged on a gantry 5 above the road a number of radio communication units 7. How a payment operation is carried out by means of radio co ⁇ munication and how the equipment in question is arranged is not a matter for this invention and shall therefore not be described in more detail here.
• US, A, 4,303,904, Chasek such a system is described, however.
• gantry 5 On the gantry 5 there are additionally arranged in both directions, video cameras 8 directed along the roadway by means of which the number plates of the vehicles can be recorded in the event a vehicle passes without performing a correct payment manouever, so that it can be searched and post-debited.
• the vehicles can be tracked between the position where the check occurs of whether a correct payment manouever has been carried out and the site where recording of the number plate takes place or such recording is stored, so that absolute certainty can be obtained that only those vehicles for which fees have not been paid will be searched and post-debited.
• the vehicles shall be successive- position-indicated along a certain travelling length, mainly the maximum travelling length required for the operation with check of payment status and as the case may be registration of payment, considering the time the operation takes in relation to occurring vehicle speeds.
• a device 9 is arranged with video cameras 10 and 11 in a stereo arrangement.
• the cameras are directed downwards at the roadway and each camera can cover an area at least corresponding to said length that the vehicle must be tracked. In the arrangement the surveillance area is caught from different angles in the two cameras.
• Fig. 2 the device is presented schematically in a vertical plane. To illustrate more clearly the principles of the invention, the positions of its different parts are altered compared with the overview in Fig. 1, the roadway and the vehicle being somewhat different than in Fig. 1.
• the pair of video cameras 10 and 11 is illustrated. Between the cameras there is the device 12 for the structured illumination.
• the cameras and the illumination device are arranged in a height level above the roadway with its lanes. This arrangement is also evident from Fig. 1.
• an optic central axis 15 and 16 for the cameras 10 and 11 runs through the respective objectives of the cameras.
• the cameras are adjusted so that these central axes meet on the surface of the roadway. Because the cameras are located at a distance from each other, only the images of the roadway will coincide on the respective image planes, while all contours over same will have various displaced positions relative to the central axis. This is a known condition in stereo arrangements and makes it possible by comparing the position of the image parts to get an idea of the position not only in the image plane but also along the central axis.
• projection lines 20, 21 have been drawn from the contour of the up>per surface of the truck 18 to the camera objective 10. It is then evident from the figure how the positions of these lines are located relative to the central axis 15. In a similar way the projection lines 22 and 23 have been shown for the contours of the passenger car 19. For camera 11 the corresponding projection lines 25 and 26 are shown for the truck 18 and 27, and 28 for the passenger car 19.
• the illumination device is shown in a front view, that is, the illumination device as seen from below in Fig. 2.
• a cross- section of the illumination device is shown, cut along the line IV-IV in Fig. 3.
• the device has the same position as shown in Fig. 2 with the front turned downwards.
• the illumination device consists of a house 35 with an opening 36 in the front side. In the house there is inserted an interwall parallel to the front side, which carries a number of sources of light 38 directed at the opening 36. These have here been shown as light diodes 39 with integrated reflectors, which reflect the light against the opening 36. Other sources of light can naturally be used, but it is important for the effect of the device that they can be controlled to a periodically twinkling light.
• a Fresnel lens 37 is inserted in the opening 36 .
• a Fresnel lens 37 is used to focuse light in the same way as other lenses, but by successive ⁇ sively, stepwise bringing back the lens surface towards the central plane of the lens, it can be made thin with principally even thickness.
• the lens 37 is so adapted to its optical characteristics that the light frcm the sources of light 38 is focused to delimited light spots on the roadway or a plane somewhat above same. The focusing shall be such, that the limited light spots appear on the vehicle irrespective of how high the vehicle portions are located.
• a pattern is projected in this way on the respective portions of the vehicles, and most important is that it appears on the large, upwardly turned portions of vehicles, that is the vehicle roof.
• Figs. 2 and 5 said light spots on the vehicles are designated by 30 and on the roadway 2, by 31. From Fig. 5, which to the left shows a recording in the camera 10 and to the right a recording in the camera 11, it is evident how the spot pattern appears in such recordings. From the Figures it should be apparent that a clear separation of the vehicles from each other, as well as from the roadway is obtained through the spot pattern.
• the device for the tracking and classification of the vehicles must function in all types of weather and types of sun radiation.
• the light radiation from the sources of light must therefore be capable of travelling through fog and falling snow, and must also give a clear light pattern in full sunshine. To achieve this, the following means are used:
• infrared light is used.
• the video cameras can be made more sensitive to this light with limited sentitivity to the shortwave sunlight, through which the relation of strength between illumination and sunlight becomes more favourable in the video recording.
• the advantage is gained that the infrared light does not affect the human eye and therefore does not disturb the vehicle driver.
• the cameras work with short time of exposure, for example 0.1 millisecond, and the spot-wise illumination is pulsed at the same rate.
• the effect of the sun radiation is strongly reduced, while the effect from the pulsed sources of light is used at least almost to its full extent.
• the described illumination device to obtain a light pattern can be varied in its embodiment.
• the light can be divided from one or two sources of light by means of a grid or an optic screen.
• a Fresnel lens for focusing a required number of lenses or focusing reflectors can be used.
• the application of the device in a road toll facility has been described, for tracking and classification of vehicles. It can however be used for other purposes of identification in other types of control stations for vehicles. It can also be applied and adapted for use in conjunction with other arrangements than stereo arrangements; a light pattern gives a clear indication of objects also seen in a mono arrangement. Thereby, a sloping direction of the light relative to a principle plane for the vehicles and the ground can be of value.

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Applications Claiming Priority (2)

Publications (1)

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Cited By (7)

Families Citing this family (1)

Citations (4)

• 1994
  • 1994-10-24 SE SE9403631A patent/SE503707C2/sv not_active IP Right Cessation
• 1995
  • 1995-10-20 AU AU38625/95A patent/AU3862595A/en not_active Abandoned
  • 1995-10-20 WO PCT/SE1995/001253 patent/WO1996013023A1/en active Application Filing

Patent Citations (4)

Non-Patent Citations (1)

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