EP2332131B1 - Stand-alone passive system for detecting a vehicle exceeding a speed limit - Google Patents

Description

FIELD OF THE INVENTION

The present invention relates to the field of autonomous passive systems, mobile or fixed, using a means of shooting to detect the exceeding of a speed limit by providing proof of the identification and speed of the vehicle.

BACKGROUND TECHNOLOGY

There are various techniques and apparatus for detecting the vehicle overrun of at least one speed limit predefined by the competent authority.

The most widespread uses information provided by a radar which is controlled by duly authorized personnel. The operator must have an optical field long enough not to be seen vehicles to control and the equipment must not be detected by anti-radar devices. Such constraints limit the possible areas of implantation of said radars and hours of use since they require the presence of an operator. Drivers thus quickly know the areas where they are located and the hours during which they are operated which allows them to escape the controls by reducing the speed in said areas and at said hours.

An improved version of the prior art is to use an autonomous system combining a radar and a digital or video camera or both. This system requires qualified personnel to pilot it and unfortunately preserves in most installations the aforementioned limitations. Some provisions do not have such limitations as for example their implementation above the road or on decks with detection of the vehicle from the rear.

Another known technique is to use an intelligent system installed in the vehicle, controlling the speed and location of the vehicle by simultaneously comparing them to an internal database that contains a map and speed limits for all road locations. Thus, if the driver reaches the speed limit in the area considered, the system warns him and if it exceeds it, said overrun is recorded on a memory card which is read by the competent authority in well defined times. Unfortunately, this system is expensive and requires a substantial infrastructure by the traffic control authority for card management and updating.

A new technique in connection with the CY2520 patent uses a camera having an adjustable shutter that allows to grasp the movement of the vehicle, which has a speed greater than the limit speed, a few centimeters during the exposure time. The vehicle being provided with two lamps, or other markings, of known distance, which leave a trace during the exposure time. The length traces left and the fact that they meet when the vehicle exceeds the speed limit, indicates that there has been overtaking. The vehicle speed can then be calculated as a function of the exposure time. The advantages of this technique are that it is passive and therefore undetectable and provides a photographic proof of exceedance. The disadvantages are that it requires specific markings on the vehicle.

• le document US3120992 qui divulgue l'estimation de la vitesse du véhicule par la mesure d'un décalage entre des caractères correspondant à des prises de vues à des instants consécutifs ;
• le document WO97/16806 qui divulgue des éléments comparables dans le même but d'utilisation ; toutefois, il effectue une conversion de la distance mesurée en pixels et compense cette distance pour prendre en compte l'angle d'inclinaison de la caméra par rapport à l'horizontale et à la hauteur de la plaque d'immatriculation sur le véhicule.

The closest state of the art is described in:

• the document US3120992 which discloses the estimation of the vehicle speed by measuring an offset between characters corresponding to shots at consecutive times;
• the document WO97 / 16806 which discloses comparable elements for the same purpose of use; however, it performs a conversion of the measured distance into pixels and compensates for this distance to take into account the angle of inclination of the camera with respect to the horizontal and the height of the license plate on the vehicle.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned problems, the present invention is directed to a self-contained passive system for detecting vehicle overshoot of the image-limiting speed limit, which is small, which can be placed indifferently on the side or at the top. of the road, undetectable by the driver of the arriving vehicle or by a radar detection device and which does not require any additional means on the vehicle.

• un moyen de détection de la présence d'un véhicule ;
• un moyen de prise de vue capable de fournir une sortie sous forme d'image numérisée ;
• un moyen de calcul, du type processeur, apte à analyser les images comportant des dépassements de vitesse ;
• un moyen de communication apte à transmettre à distance des données relatives aux infractions constatées ;

ledit véhicule comportant, à l'avant et à l'arrière, une plaque d'immatriculation possédant des caractères alphanumériques de dimensions connues.The system according to the invention essentially comprises:

• means for detecting the presence of a vehicle;
• a shooting means capable of providing an output in the form of a digitized image;
• calculating means, of the processor type, capable of analyzing the images comprising overspeeds;
• a means of communication capable of remotely transmitting data relating to the offenses observed;

said vehicle having, at the front and at the rear, a license plate having alphanumeric characters of known dimensions.

• T (exprimé en ms) correspond au temps écoulé entre deux images consécutives de la plaque d'immatriculation (1) prises par le moyen de prise de vue (20) ;
• X_π (exprimé en mm) correspond au déplacement réel du véhicule et est obtenu au moyen de la formule suivante XT_π = X / sin θ dans laquelle X (exprimé en mm) correspond au déplacement horizontal entre deux images consécutives et sin θ correspond au sinus de l'angle formé par l'axe optique du moyen de prise de vue (20) et l'axe de la route, X étant lui même obtenu au moyen de la formule suivante X = Y (Xc / Yc) dans laquelle Y (exprimée en mm) correspond à la hauteur du caractère inscrit sur la plaque et Xc et Yc (exprimés en pixels) correspondent respectivement au déplacement horizontal et à la hauteur d'un caractère.

It is essentially characterized in that the real speed of the vehicle V (expressed in Km-h) is obtained by means of the following formula V = (X _π / T) (3600/1000), in which:

• T (expressed in ms) corresponds to the time elapsed between two consecutive images of the license plate (1) taken by the shooting medium (20);
• X _π (expressed in mm) corresponds to the real displacement of the vehicle and is obtained by means of the following formula XT _π = X / sin θ in which X (expressed in mm) corresponds to the horizontal displacement between two consecutive images and sin θ corresponds to the sinus of the angle formed by the optical axis of the shooting means (20) and the axis of the road, X being itself obtained by means of the following formula X = Y (Xc / Yc) in which Y (expressed in mm) corresponds to the height of the character written on the plate and Xc and Yc (expressed in pixels) respectively correspond to the horizontal displacement and the height of a character.

The system in question performs a conversion of the distance measured in pixels and compensates for this distance to take into account the angle between the optical axis of the shooting medium and the axis of the road by using as a reference of the height characters of the plate.

So it seems new and original compared to the documents US3120992 and WO97 / 16806 .

• le moyen de prise de vue, prend la première image à partir de la réception du signal de détection de la présence d'un véhicule ;
• le moyen de prise de vue est constitué de deux dispositifs de prise de vue, capables de fournir une sortie sous forme d'image numérisée, disposés l'un au dessus de l'autre et ayant le même champ visuel par rapport au véhicule.

According to particular features of the invention,

• the shooting means, takes the first image from the reception of the detection signal of the presence of a vehicle;
• the means of shooting consists of two cameras, capable of providing an output in the form of a digitized image, arranged one above the other and having the same visual field with respect to the vehicle.

PRESENTATION OF FIGURES

The features and advantages of the invention will appear more clearly on reading the detailed description which follows of at least one preferred embodiment thereof given by way of non-limiting example and shown in the accompanying drawings.

• la figure 1 est une vue schématique de la plaque d'immatriculation ;
• la figure 2 est une vue schématique du système selon l'invention positionné au bord de la chaussée pour la prise d'images de l'avant d'un véhicule se déplaçant sur une route ;
• la figure 3 est une vue simplifiée de la figure 2 montrant les éléments trigonométriques liés au déplacement réel du véhicule et à la trace de celui-ci sur l'image pendant le même intervalle de temps ;
• la figure 4 est une vue schématique montrant le déplacement horizontal d'un point type du véhicule entre deux prises de vues ;
• la figure 5 est une vue schématique montrant deux images de la plaque d'immatriculation prises, à quelques fractions de secondes, voir millisecondes, d'intervalle, par deux moyens de prises de vues placés au l'un au dessus de l'autre ;
• la figure 6 est une vue regroupant la plaque d'immatriculation de la figure 5 exprimée en pixels et les éléments trigonométriques de la figure 3 en vue d'établir le rapport d'infraction ;
• la figure 7 est une vue schématique du système selon l'invention positionné au bord de la chaussée pour la prise de vues de l'arrière d'un véhicule se déplaçant sur une route ;
• la figure 8 illustre la configuration de la figure 3 dans laquelle les prises de vues se font à l'arrière du véhicule selon un axe connu ;
• la figure 9 est similaire à la figure 2 mais s'applique à deux voies de circulation tout en utilisant le même angle entre l'axe optique de la caméra et la route.

On these drawings:

• the figure 1 is a schematic view of the license plate;
• the figure 2 is a schematic view of the system according to the invention positioned at the edge of the road for taking pictures of the front of a vehicle moving on a road;
• the figure 3 is a simplified view of the figure 2 showing the trigonometric elements related to the actual movement of the vehicle and the trace thereof on the image during the same time interval;
• the figure 4 is a schematic view showing the horizontal displacement of a typical point of the vehicle between two shots;
• the figure 5 is a schematic view showing two images of the license plate taken, at intervals of a few seconds, or even milliseconds, by two means of shooting placed one above the other;
• the figure 6 is a view grouping the license plate of the figure 5 expressed in pixels and the trigonometric elements of the figure 3 to establish the offense report;
• the figure 7 is a schematic view of the system according to the invention positioned at the edge of the road for shooting the rear of a vehicle moving on a road;
• the figure 8 illustrates the configuration of the figure 3 in which the shots are taken at the rear of the vehicle along a known axis;
• the figure 9 is similar to the figure 2 but applies to two lanes of traffic while using the same angle between the optical axis of the camera and the road.

DETAILED DESCRIPTION OF THE INVENTION

The autonomous passive system for the detection, by image capture, of the passing by a vehicle of the authorized speed limit, according to the invention, is detailed by means of the Figures 1 to 9 . It can work in any lighting situation.

The figure 1 illustrates a license plate (1) provided with identification data (2) of the vehicle whose character dimensions, such as width and height, are initially known.

• un moyen (21) de détection de la présence d'un véhicule (22) ;
• un moyen (20) de prise de vue capable de fournir une sortie sous forme d'image numérisée ;
• un moyen (23) de calcul, du type processeur, apte à analyser les images comportant des dépassements de vitesse ;
• un moyen de communication (24) apte à transmettre à distance des données relatives aux infractions constatées.

The figure 2 illustrates the complete representation of the various constituent sub-assemblies of the invention as arranged on the site, namely:

• means (21) for detecting the presence of a vehicle (22);
• image pickup means (20) capable of providing an output as a digitized image;
• calculating means (23), of the processor type, capable of analyzing the images comprising overspeeds;
• a means of communication (24) able to remotely transmit data relating to the offenses observed.

The vehicle comprises, at the front and at the rear, a license plate (1) having alphanumeric characters of known dimensions;

The detecting means (21) is arranged before the photographing means (20) at the edge of the road at a point where the first image is to be taken as soon as it detects the presence of a vehicle (22) for transmitting a presence signal to said means (20). Said detection means can be made by any type of device and can be placed indifferently above or on the sides of the road.

The two images are taken, by one or two cameras, to fractions of seconds, or even milliseconds, of interval, in a time chosen to give the desired speed of analysis in pixels. When the reception time of the two consecutive images increases, the distance traveled by the vehicle during this time also increases and the analysis of km / h for each pixel decreases. The distance traveled by the vehicle must not be such that the characters in the second image appear wider than in the first because they have no common reference.

In the figure 2 , the means (20) are placed at the edge of the road with the same optical axis (62) in the horizontal plane, at an angle, relative to the axis (66) of the road, of the order 30 °. They are superimposed and very close to each other. Ideally, a single means (20) should take two images with a time interval of the order of a few milliseconds which is not possible to date with existing devices on the market.

The means (20) are preferably associated with the processor (23) which immediately detects the infringements and which preferably transmits them via the communication means (24) to the control center. He can immediately transmit "sms" on the driver's mobile phone so that he immediately reduces his speed and / or send the registration number to an electronic display board placed on the side of the road. He can also prepare a report on the offense that he sends to the driver by email.

The figure 3 illustrates the relationship between the distance (63) traveled by the vehicle (22) during the period under consideration and the distance (64) recorded on the image and depending on the optical axis (62) of the camera (s) (20). ) with respect to the axis (66) of movement of the vehicle, when the camera is disposed on the edge of the road.

The first picture is taken in the position of the vehicle as illustrated and the second at the axis (67). The optical axis (62) of the camera forms with the axis (66) of movement of the vehicle, an angle (65), or (θ) through the center of the vehicle and the license plate. The angle (65) is approximately the same for all the points of said plate because the distance of the means (20) relative to the vehicle is greater than that of the center of the plate relative to its edges at the point of considering parallel between them the corresponding axes. On the other hand, angles extremes of the vehicle with the center of the means (20) are substantially different. If the plate is not centered, the program knows the angle corresponding to the optical axis.

In the first image, the center of the vehicle appears in the center of the optical axis. In the second image, after having traveled the horizontal distance (63), the center of the vehicle appears at the horizontal distance (64) offset from the center of the image. The distance traveled by the vehicle can be calculated using the distance (64) recorded on the image and the axis (66).

The figure 4 illustrates the vehicle (22) and two different focal levels (71) and (72) where both images are taken. The points (74) and (76) are in the center of the first and second images, respectively. The mark (73) which is located in the center of the vehicle (22) appears at the center (74) of the first image and at the point (75) of the second image, separated by the horizontal distance (64), when the drawings are bunk. The second image has a focal plane (72) that is captured when the vehicle has traveled the distance (63) and has reached the vertical level (68). The focal plane (72) perpendicularly intercepts the optical axis (69). If the two images are superimposed on another point (74) of the first image, it appears on (76) of the second image and has moved by a distance (64) corresponding to the horizontal displacement of the other vehicle. the two images. The assumption that the axes (69) and (62) are parallel remains valid because the distance between the means (20) and the vehicle is thirty to one hundred times greater than the distance between the levels (71) and (72).

The figure 5 illustrates a small portion of the two images taken that show only the license plate. They are placed in perfect superposition with digital methods making it possible to make appear the second image in the semi transparent form so as to make them both visible. They also appear displaced in height since the vertical position of the means (20) is not identical to that of the license plate. A height displacement can be used to calculate the speed of the vehicle as the means (20) are placed above the road but in this case only the displacement in the horizontal plane is important. The digital program first recognizes the registration number on one of the images and then recognizes and finds the height of a character in pixels as illustrated on the figure 5 . Then, to find the horizontal displacement, it takes the same small area on two images around the character that was measured and moves an image horizontally and vertically after subtracting, in any motion, the corresponding pixel values from a picture in relation to each other until the sum of all the pixels is as small as possible. The algorithm and stroke that the drawings must perform to coincide can be easily done manually with an accuracy of one pixel or programmed.

• les images, selon la figure 5, de la plaque d'immatriculation précisant, en pixels, la hauteur d'un caractère et le déplacement horizontal de celui-ci ;
• la représentation schématique, selon la figure 3, de la position moyen (20) en relation avec la route et le véhicule ;

et qui sert à établir le rapport d'infraction.The figure 6 illustrates an example that contains:

• the images, according to the figure 5 , the license plate specifying, in pixels, the height of a character and the horizontal displacement thereof;
• the schematic representation, according to the figure 3 the average position (20) in relation to the road and the vehicle;

and which serves to establish the offense report.

1. a) données constantes connues données à titre indicatif :
   • angle du moyen (20) avec l'axe de la route : θ = 0,52 radians
   • temps écoulé entre les deux saisies : T = 4 ms
   • hauteur du caractère inscrit sur la plaque (ou de toute autre partie du véhicule) : Y = 100 mm
   • vitesse limite : A = 100 Km-h
2. b) données analysées par le programme digital :
   • hauteur du caractère : Yc = 80 pixels
   • déplacement horizontal du caractère : Xc = 55 pixels
3. c) données de circulation :
   • déplacement horizontal visualisé entre deux images consécutives : X en mm
   • déplacement réel du véhicule sur la route : X_π en mm
   • vitesse du véhicule : V en Km-h
4. d) équations utilisées pour le calcul des variables :
   • X = Y (Xc / Yc) = 69 mm
   • X_π = X 1 sin θ = 138 mm
   • V = (X_π / T) (3600 / 1000) = 124 Km-h

soit un dépassement de 124 - 100 = 24 Km-hThe data used are as follows:

1. a) known constant data given as an indication:
   • angle of the means (20) with the axis of the road: θ = 0.52 radians
   • time elapsed between the two entries: T = 4 ms
   • height of the character written on the plate (or any other part of the vehicle): Y = 100 mm
   • speed limit: A = 100 Km-h
2. b) data analyzed by the digital program:
   • height of the character: Yc = 80 pixels
   • horizontal displacement of the character: Xc = 55 pixels
3. c) traffic data:
   • horizontal displacement visualized between two consecutive images: X in mm
   • actual displacement of the vehicle on the road: X _π in mm
   • speed of the vehicle: V in Km-h
4. d) equations used for calculating variables:
   • X = Y (Xc / Yc) = 69 mm
   • X _π = X 1 sin θ = 138 mm
   • V = (X _π / T) (3600/1000) = 124 Km-h

an overtaking of 124 - 100 = 24 Km-h

If the license plate is not in the center of the image, the angle θ will be corrected by means of a table of values stored in the processor.

The figure 7 illustrates the configuration of the figure 2 wherein the shooting is at the rear of the vehicle after the presence detecting means has transmitted the appropriate signal to the means (20).

The figure 8 illustrates the configuration of the figure 3 wherein the shots are at the rear of the vehicle along a known axis. The scanned displacement on the images corresponds to the vertical displacement (64) and the actual displacement of the vehicle corresponds to the calculated displacement (63). The system can be positioned on each lane of a multi-lane road with pictures taken from the front or rear of vehicles. It can also be positioned high on the side of the road and take pictures over vehicles to calculate the vertical displacement of images while ignoring the horizontal one.

The figure 9 is similar to the figure 2 but with two presence detection means (21) and (26) for two traffic lanes while using the same angle between the optical axis of the means (20) and the road.

The system may store images but, in an advantageous embodiment, it may comprise communication means (24), such as for example a GSM telephone, capable of sending the photos to an authorized vehicle based on the zone in order to transmit to the interested in a call or email regarding the offense.

The system can, in an even more advantageous embodiment, integrate in a same module, the means (20), the computer (23) and the communication means (24).

The system according to the invention combines the advantages related to the portable and low cost aspects of autonomous systems. He brings proof of the offense to the competent authorities. It can be placed on the sides or at the top of the road under any circumstances.

Of course, those skilled in the art will be able to carry out the invention as described and represented by applying and adapting known means.

It may also provide other variants without departing from the scope of the invention which is determined by the content of the claims.

Claims (6)

1. Stand-alone passive system for detecting a vehicle exceeding the authorised speed limit, comprising substantially:

   - a means (21) for detecting the presence of a vehicle (22);

   - an imaging means (20) able to provide an output in the form of a digital image;

   - a means (23) for calculating, of the processor type, able to analyse the images comprising a vehicle exceeding the authorised speed limit;

   - a means of communication (24) able to remotely transmit data relating to the offence observed;
   said vehicle comprising, in front and at the rear, a registration plate (1) having alphanumerical characters of known dimensions; and wherein the actual speed of the vehicle V, expressed in Km-h, is obtained using the following formula V = (X_π T) (3600/1000), wherein:

   - T, expressed in ms, corresponds to the time elapsed between two consecutive images of the registration plate (1) taken by the imaging means (20);

   - X_π, expressed in mm, corresponds to the actual movement of the vehicle and is obtained using the following formula X_π = X / sin θ wherein X , expressed in mm, corresponds to the horizontal movement between two consecutive images and sin θ corresponds to the sine of the angle formed by the optical axis of the imaging means (20) and the axis of the road, X being obtained, in turn, using the following formula X = Y (Xc / Yc) wherein Y, expressed in mm, corresponds to the height of the characters inscribed on the plate and Xc and Yc, expressed in pixels, respectively correspond to the horizontal movement and the height of the characters.
2. System, according to claim 1, characterised in that the imaging means (20), takes the first image starting from the reception of the detection signal of the presence of a vehicle transmitted by the means (21).
3. System, according to claim 1, characterised in that the imaging means (20) is comprised of two imaging devices, able to provide an output in the form of a digital image, arranged one on top of the other and having the same visual field in relation to the vehicle.
4. System, according to claim 1, characterised in that the processor (23) is associated to a means for storing the images relating to the offences observed.
5. System, according to claim 1, characterised in that the means of communication (24) transmits the images and the data relating to the offences observed, to the competent authority.
6. System, according to claim 1, characterised in that the means of communication (24) transmits the data relating to the offences observed directly to the mobile telephone of the offender.

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