EP0649553B1 - Device and process for the detection of one or more vehicle wheels - Google Patents

Abstract

PCT No. PCT/FR93/00699 Sec. 371 Date Feb. 8, 1995 Sec. 102(e) Date Feb. 8, 1995 PCT Filed Jul. 6, 1993 PCT Pub. No. WO94/01847 PCT Pub. Date Jan. 20, 1994A device for detecting one or several wheels of a vehicle or of a wheeled engine and a process using this device. The device is constituted by at least one electromagnetic loop and by an evaluation unit. The electromagnetic loop or loops have a small dimension in the direction of the displacement of the vehicle or of the axis of the roadway, which is less than the diameter of the wheels of the vehicles to be identified, and a rectangular shape and/or a rectilinear arrangement disposed perpendicularly to the axis of the roadway, the loop or loops being sensitive in a distinct and opposed manner to the electromagnetic influences of the metallic masses moving in translation and in rotation, at the wheels of the vehicle.

Description

The present invention relates to the field of analysis of the identification and classification of vehicles or wheeled rolling machines, in particular when the latter move within the framework of their normal use, and relates to a device for detect in particular one or more wheels of a vehicle or of a mobile rolling machine, as well as a method of detection, analysis and classification of vehicles or machine using this device.

There are currently already different types of systems making it possible to identify rolling vehicles, among which there may be mentioned in particular piezoelectric, resistive, optical, ultrasonic and microwave sensors, as well as devices with pneumatic tubes or with electromagnetic loops. .

The latter type of identification devices is currently in the form of a loop or two rectangular loops, large dimensions of the order of 1.5 m by 2 m (2 m being measured in the width direction of the track), arranged on or in the roadway and making it possible to collect a signal representative of the whole body of the vehicle including the wheels detected during the passage of the latter over the loop (s). The shape of the signal collected and, if necessary, the offset between two signals collected by two loops, arranged with a spacing between them in the direction of movement of the vehicle, allow, respectively, to determine the nature of the light vehicle, heavy vehicle as well than its speed of movement. Such a device is known in particular from document EP-A-0035960.

However, this known device does not allow a fine or exact identification of the detected vehicles, authorizing in particular their classification in the ten categories defined by the Organization of Cooperation and Economic Development (OECD) or in the fourteen categories of the French Data Collection System (SIREDO).

Indeed, this device does not detect the number of axles of the vehicle and, to carry out this detection, it is necessary to add to it an additional device of the pneumatic tube or piezoelectric sensor type raising the passage of the axles as indicated in FR-A-2 549 625

The result is a complex assembly requiring constant maintenance due to the presence of mechanical type sensors, subject to high wear.

The object of the present invention is in particular to overcome the aforementioned drawbacks.

For this purpose, it uses a device constituted by at least one electromagnetic loop positioned on the roadway or in the roadway and by a unit for evaluating the influence of the passage of a vehicle at the level of said loop or loops, characterized in that the electromagnetic loop (s) 2 (s), each composed of one or more turns, has (on the one hand) a small dimension in the direction of movement of the vehicles or the axis of the road, less than the diameter of the wheels of the vehicles to be identified, and, on the other hand, a preferably rectangular shape and / or an arrangement arranged perpendicular to the axis of the road, the loop or loops being arranged at least at one or two rolling tracks of a roadway and sensitive, distinctly and opposite, to the electromagnetic influences of the metallic masses of the carcass or chassis of vehicles , Firstly , and metallic masses of the tires of the corresponding wheels, on the other hand. Such loops are known from FR-A-2 254 842 but the known evaluation units exploiting the signals of these loops did not exploit the fact (incidentally unknown until now) that the influences of the metallic masses of the carcass and tires on this type of loop are opposite.

The invention relates to a method for detecting, analyzing and classifying vehicles or rolling vehicles using the above-mentioned device, characterized in that it consists in detecting the electromagnetic influences on the one hand, of the metallic masses of the carcass or chassis of a vehicle and, on the other hand, masses metallic tires of the wheels of said vehicle, in a distinct and opposite manner, by means of at least one electromagnetic loop, arranged on or in the roadway and having a small dimension in the direction of movement of the vehicles or the axis of the roadway, to produce a signal indicating the number and the positioning of the wheels, between them and in relation to the carcass or chassis of the vehicle, to identify the precise nature of the vehicle analyzed and to classify the latter in predetermined categories, based essentially on the number and the longitudinal arrangement of the wheels or axles, and to store the data collected over a defined period with a view to their subsequent exploitation.

• la figure 1 représente de manière schématique le dispositif vu de dessus;
• les figures 2 à 17 représentent des variantes de réalisation en nombre, en forme et en sens d'enroulement des boucles faisant partie du dispositif conforme à l'invention;
• la figure 18 représente le signal en tension généré par une voiture à la sortie du détecteur électromagnétique faisant partie du dispositif de l'invention;
• la figure 19 représente le signal en tension à la sortie du détecteur, généré par un autocar;
• la figure 20 représente le signal en tension à la sortie du détecteur, généré par un tracteur à deux essieux et sa semi-remorque à trois essieux;
• la figure 21 représente le signal en tension, avec une sensibilité différente, à la sortie du détecteur, généré par un tracteur à deux essieux, et sa semi-remorque à trois essieux, dont le premier essieu est relevé, et,
• la figure 22 représente un tableau des catégories et de leurs silhouettes identifiables par le dispositif selon l'invention.

The invention will be better understood from the description below, which relates to preferred embodiments, given by way of nonlimiting examples, and explained with reference to the appended schematic drawings, in which:

• Figure 1 shows schematically the device seen from above;
• Figures 2 to 17 show alternative embodiments in number, shape and winding direction of the loops forming part of the device according to the invention;
• FIG. 18 represents the voltage signal generated by a car at the output of the electromagnetic detector forming part of the device of the invention;
• FIG. 19 represents the voltage signal at the output of the detector, generated by a bus;
• FIG. 20 represents the voltage signal at the output of the detector, generated by a two-axle tractor and its three-axle semi-trailer;
• FIG. 21 represents the voltage signal, with a different sensitivity, at the output of the detector, generated by a two-axle tractor and its three-axle semi-trailer, the first axle of which is raised, and,
• FIG. 22 represents a table of the categories and their silhouettes identifiable by the device according to the invention.

According to the invention, and as shown in Figures 1 to 21 of the accompanying drawings, the device for detecting in particular one or more wheels of a vehicle or rolling vehicle, comprising at least one electromagnetic loop and a unit of evaluation, is essentially characterized in that the electromagnetic loop (s) 2, each composed of one or more turns, has (on the one hand) a small dimension 1 in the direction of movement vehicles or of the X axis of the roadway 1, smaller than the diameter of the wheels of the vehicles to be identified, and, on the other hand, a preferably rectangular shape and / or an arrangement arranged perpendicular to the X axis of the roadway 1 , the loop (s) 2 being arranged at least at one or two tracks 1 "of rolling of a track 1 'of the roadway 1 and sensitive (s), distinctly and opposite, to the influences electromagnetic, on the one hand, met masses allics of vehicle bodies (carcass, chassis, underbody) and, on the other hand, metallic masses of the corresponding wheels.

The loop (s) 2 advantageously have an inductance between 40 and 700 μH and is (are) made up of n turns (n between 1 and 10) of an insulated conducting wire of 0.2 with a cross-section of approximately 3 mm ² , placed on or in the pavement 1.

According to a first characteristic of the invention, shown in Figure 1 of the accompanying drawings, the evaluation unit is composed, on the one hand, of an electromagnetic detector 3 detecting the variations in frequency voltage (generated by the current induced) of an alternating signal passing through the loop (s) 2 which is (are) connected to it and delivering a proportional signal corresponding to said variations, on the other hand, from a signal processing card 4 analyzing the signal from said electromagnetic detector 3 and determining in particular, by means of microprocessor means controlled by a computer program, the number wheels belonging to the same vehicle with a view to its classification and, finally, a memory 5 for storing the informative data delivered by said processing card, which can be read in situ and / or remotely, with possible transfer of its content, elements 3 to 5 of said evaluation unit being mounted in a protective box, placed close or not to roadway 1.

The electromagnetic detector 3, for example of the type known under the designation SL29C and marketed by the company CFEE (two-way detector and with automatic adjustment), consequently detects the result of variations in the voltage and the frequency of an alternating signal. in the loop (s) 2 due, on the one hand, to the metallic masses of the vehicle (carcass, underbody, chassis, engine in particular) and, on the other hand, to the metallic masses of the wheel or wheels, more particularly of the corresponding tire or tires, of the vehicle to be studied, in particular the variation of the inductance of the circuit formed by each loop 2.

The frequency f = 1 / (2π√LC) of the oscillator thus formed is compared to the frequency of a fixed oscillator. This frequency is applied to the input of a phase locked loop circuit whose role is to provide a DC voltage at its output in relation to the input frequency. The signal resulting from the output of the loop (s) -detector couple is characteristic of the number of wheels and therefore of the axles but also of the envelope (carcass - chassis) of the vehicle representing its length and the distance from the latter with respect to on the roadway 1. The voltage variation due to a wheel, when passing through a loop, is of the order of 200 to 800 millivolts (for the aforementioned type of detector - Figures 18 and 21) and is opposite to the direction of the variation generated by the metallic masses of the body of this same vehicle.

Indeed, a loop 2 according to the invention, associated with an electromagnetic detector 3, makes it possible to highlight in a distinct manner the influence of the carcass or chassis of the vehicle and the influence of the wheels, more particularly of the tires, but also of the discs, drums, rims, etc., on the frequency of the signal passing through the said loop (s) 2.

Thus, these influences generate opposite or opposite variations in the frequency and the voltage of said signal as shown in FIGS. 18 to 21 which represent DC voltage signals delivered by the electromagnetic detector 3 and whose amplitudes vary according to variations in frequency of signals passing through loops 2.

These results could be explained by the fact that, the loop (s) 2 constituting a first circuit provided with a generator, the metallic masses of a vehicle, passing over such a circuit, generate a variation of the magnetic field produced around said first circuit and, consequently, a variation of the flux embraced by a second circuit, constituted by the metallic masses of the wheel and more particularly by the torus formed by the rim and the metallic reinforcements of the tire, during its passage over said first circuit.

This second circuit will therefore be the seat of an induced current obeying LENZ's law.

Similarly, we are witnessing the creation of a return circuit current in said first circuit constituted by the loop or loops 2. However, according to the aforementioned law, the induced current will tend by its effects to the cause which gave birth to it. , which explains the opposite variations of the collected signals.

In addition, the two aforementioned circuits have, between them, a mutual inductance with variable permeability by the presence of metallic elements in translation and metallic elements in rotation.

We can clearly see in Figures 18 to 21 the positive variations, in the form of a flattened plate or dome, generated by the carcass or the chassis of the vehicle in question and the peaks of negative variation generated by the wheels in rotation of said vehicle (relative at the reference R of the signal in the form of a resting voltage of a few volts corresponding to a zero variation in the frequency of the voltage).

It is even possible to identify in FIG. 20 small positive peaks, integrated into the negative peaks, corresponding to the passage, at the level of loop 2, of the attributes of the wheel or wheels (suspension, rocket, bridge, support, etc.) .

It should also be noted that the amplitude of the signals collected at the level of the magnetic detector 3 is independent of the speed at which the vehicle passes over the loop (s) 2, hence an identical measurement and analysis sensitivity. at low speed and high speed.

In addition, it is also possible to determine, in particular for a heavy vehicle, the bearing of one or more wheels or axles.

In fact, as shown in FIG. 21 of the appended drawings, a raised wheel or axle causes the signal to vary in the same direction as the metallic mass of the carcass or chassis (see positive peak preceding the two negative peaks in FIG. 21 ).

The computer program, if necessary derived from a known signal processing program, as well as the signal processing card 4 advantageously allows the classification of vehicles by category, by discriminating them by means of the number of axles, distances between axles, the length of the carcass or chassis and distances between roadway and underbody, on the one hand, between the axles and, on the other hand, in front or behind the axles.

These latter distances are specific characteristics of the morphology of certain vehicles, in particular buses and coaches having a low lateral metal envelope.

In accordance with a preferred embodiment of the invention, the dimension I or width of the loop (s) 2 in the direction of movement of the vehicles to be analyzed or the X axis of the Pavement 1 is approximately of the order of magnitude of the width of the bearing surface on the ground of the tires of the wheels of the vehicles to be analyzed (dimensions approximately similar).

Thus the width l of the loop (s) 2 is preferably of the order of 0.3 meters, for the detection of heavy goods vehicle wheels and preferably of the order of 0.15 meters for the detection of the wheels. light vehicles.

According to a first embodiment of the invention, shown in Figures 3 and 5 of the accompanying drawings, the detection device comprises one or two loop (s) 2 rectangular having a length L between 0.50 m and 1.20 m and arranged (s) each on or under a rolling track 1 "of a track 1 ', perpendicular to the longitudinal axis of this (s) ci.

According to a second alternative embodiment, shown in FIG. 4 of the accompanying drawings, said detection device comprises a single rectangular loop 2 encompassing the two rolling traces 1 "of a track 1 '.

According to a third alternative embodiment of the invention, shown in Figures 12 to 16 of the accompanying drawings, said detection device comprises an association of two loops 2, constituted by the same conductive wire connected to a single detector 3 and each of which is placed on or under one of the two rolling tracks 1 "of the wheels of the same track 1 'of the roadway 1, each of said loops 2 may include a given number of turns, identical or indifferent.

According to a fourth alternative embodiment, there is provided an assembly of at least two loops 2, each connected to a separate electromagnetic detector 3 and arranged in an alignment perpendicular to the axis X of the roadway 1 or to the direction of movement of the vehicles, said set of loops 2 extending either over or under a single rolling track 1 "of track 1 ', or approximately over the entire width of track 1' (Figures 6 to 10).

Although the loop (s) 2 preferably have a rectangular shape, it (s) can (can) also be of different shape, namely, in parallelogram, square or round (Figures 6 to 10) see oval or elliptical ( not shown).

In addition, in the case of an arrangement or an alignment of several loops 2, the latter can be separated, tangent (FIG. 8) or intersecting.

With a view to their installation on or in the pavement 1, the loop (s) 2 can (can) be secured to one or more flexible and resistant sheets or bands, rather woven or clothed, of identical or complementary characteristics and consistent, for example, in rubber, plastic, synthetic products or resin, these sheets or strips being able to sandwich the wires of turns of the loop (s) 2, having an adhesive face allowing the bonding of the or loop (s) 2 on the roadway 1 and themselves constituted by marking bands, for example stop band, line "give way", axis or edge band or the like.

Thus, said loop (s) 2 can (can) be secured to one or more sheets constituting temporary supports, if necessary perforated, placed on the roadway 1 and secured together by a localized or general coating penetrating through the openings, the sheets being able to be biodegradable or dissolvable by a component in particular of the binder of the coating or by heat.

According to a characteristic of the invention, the detection device can, in addition, be associated with or integrate another detection and data collection system relating to vehicles such as, for example, a large electromagnetic loop device. dimension, a piezoelectric sensor, a resistive sensor, a piezo-polymer sensor, an optical sensor, a hyper-frequency sensor or an ultrasonic sensor, in order to collect additional information relating to the vehicle to be studied, allowing '' further refine the identification of said vehicle.

As shown in Figure 11 of the accompanying drawings, the detection device according to the invention may also include a loop 2, of small dimension in the direction of movement of the vehicles, arranged in a loop 2 'of large dimension, the two loops 2 and 2 ′ being produced by the same conducting wire and connected to the same electromagnetic detector 3, making it possible to determine the length and the speed of movement of the vehicle to be studied.

The present invention also relates to a method for detecting, analyzing and classifying rolling vehicles using the device described above, characterized in that it consists in detecting the electromagnetic influences, on the one hand, of the masses of the carcass or chassis of a vehicle and, on the other hand, of the metallic masses of the tires of the wheels of said vehicle, in a distinct and opposite manner, by means of at least one electromagnetic loop 2, arranged on or in the roadway 1 and having a small dimension in the direction of movement of the vehicles or of the axis X of the roadway 1, to produce a signal indicating the number and the positioning of the wheels, between them and relative to the carcass or chassis of the vehicle, to identify the precise nature of the vehicle analyzed and to classify it in predetermined categories, based essentially on the number and the longitudinal arrangement of s wheels or axles, and to store the data collected over a defined period for later use.

According to a characteristic of the invention, the said method can consist in particular of noting the variation of electromagnetic quantities or of frequency or of voltage of an alternating signal passing through the loop (s) 2, during the passage of a vehicle. on this or these latter (s), following the electromagnetic influence, in particular at the level of the inductance of the loop (s) 2, of the carcass or chassis of the vehicle, on the one hand, and of the tires of the corresponding wheels, on the other hand.

According to an alternative embodiment of the invention, the said method can consist, by means of several independent loops 2 arranged perpendicular to the axis X of the roadway 1 and each producing its own signal, to transversely note the positioning of one or more several single or twin wheels of a given vehicle, and therefore the positioning of the latter on track 1 ', and to scan said vehicle by longitudinal sections, thus making it possible to reconstruct the imprint or the magnetic signature of said vehicle allowing its comparative identification precise.

Advantageously, said method will also make it possible to determine the length of the carcass or the chassis and the distances between roadway 1 and underbody between the axles, on the one hand, and in front and behind the axles, on the other hand .

According to another alternative embodiment of the invention, said method could also consist, by the additional implementation of an ultrasonic sensor, in determining the profile or the silhouette of the vehicle to be analyzed, so as to be able to distinguish between two vehicles being both provided with five axles, but one of which has a platform and the other of which is covered.

According to another alternative embodiment of the invention it is possible, by the additional implementation of a large electromagnetic loop 2 ′, associated with a loop 2 as described above, these two loops being constituted by the same common thread (therefore associated in series), to also determine, by analyzing the signal collected, the speed of travel and the length of the vehicles detected.

In fact, the latter data can be deduced from the distances between the successive leading edges of the signal collected by the electromagnetic detector 3 connected to said loops 2 and 2 ′, corresponding to the passage of said vehicle at the level of loop 2 and of loop 2 '.

According to a characteristic of the invention. the prior installation of the loop (s) 2 in the pavement 1 can advantageously be carried out by means of a hole saw making it possible to obtain suitable impressions or cutouts of 2 to 3 cm in width and depth in said pavement 1.

• comptage des essieux,
• comptage des roues, simples ou jumelées,
• comptage des véhicules,
• comptage des véhicules par catégorie
• la détermination du positionnement transversal des roues par rapport à une référence, préférentiellement l'axe de la voie,
• la détermination du positionnement transversal des véhicules par rapport à une référence, préférentiellement l'axe de la voie,
• la détermination du positionnement longitudinal des roues d'un même véhicule permettant la classification par catégorie, distance inter-essieux,
• la discrimination de véhicules atypiques par leur signature,
• la discrimination entre roue simple et roue jumelée,
• la mesure de vitesse, distance inter-véhicules, longueur de véhicules,
• l'identification des véhicules et aéronefs atypiques par exemple sur aéroport.

The device according to the invention is particularly intended for or for:

• axle counting,
• wheel counting, single or twin,
• vehicle counting,
• counting vehicles by category
• determining the transverse positioning of the wheels relative to a reference, preferably the axis of the track,
• determining the transverse positioning of the vehicles with respect to a reference, preferably the axis of the track,
• determining the longitudinal positioning of the wheels of the same vehicle, allowing classification by category, distance between axles,
• discrimination of atypical vehicles by their signature,
• discrimination between single wheel and twin wheel,
• measurement of speed, inter-vehicle distance, length of vehicles,
• the identification of atypical vehicles and aircraft, for example at an airport.

Of course, the invention is not limited to the embodiments described and shown in the accompanying drawings. Modifications remain possible, in particular from the point of view of the constitution of the various elements, or by substitution of technical equivalents, without thereby departing from the scope of protection of the invention.

Claims (18)

1. Device constituted by at least one electromagnetic loop positioned on or in the roadway and by a unit for evaluating the influence of the passage of a vehicle past said loop or loops, the electromagnetic loop or loops (2) each being composed of one or more turns and having, on the one hand, a small dimension (1) in the direction of travel of the vehicles or of the axis (X) of the roadway (1), and, on the other hand, a preferably rectangular shape and/or an arrangement disposed perpendicularly to the axis (X) of the roadway (1), the loop or loops (2) being disposed at least in the region of one or two of the rolling tracks (1") of a lane (1') of the roadway (1), characterised in that the dimension (1) or width of the loop or loops (2) is substantially equal to the width of the bearing surface on the ground for the wheels of the vehicles to be analysed, that is preferably about 0.3 metre for the detection of heavy goods vehicles and about 0.15 metre for the detection of light vehicles and in that the evaluating unit is composed, on the one hand, of an electromagnetic detector (3) noting the variations of voltage and of frequency of an alternating signal moving within the loop or loops (2) connected to it by virtue of the passage of a vehicle past the loop or loops (2) and delivering a proportional signal corresponding to said variations, on the other hand, of a signal-processing card (4) analysing the signal emitted from the electromagnetic detector (3) and determining, in particular, by microprocessor means controlled by a computer program, the number of wheels belonging to the same vehicle for its classification and, finally, a memory (5) for storage of data delivered by said processing card, adapted to be read in situ and/or remotely, with optional transfer of its contents, the elements (3 to 5) of said evaluating unit advantageously being mounted in a protective casing, disposed adjacent or not to the roadway (1).
2. Device according to claim 1, characterised in that the computer program permits the classification of the vehicles by category, discriminating between them by means of the number of axles, the distance between axles, the length of the body or chassis and the distances between the roadway and the bottom of the body, on the one hand, between the axles and, on the other hand, to the front or rear of the axles.
3. Device according to any one of claims 1 and 2, characterised in that it comprises one or two rectangular loops (2) having a' length (L) comprised between 0.50 m and 1.20 m and each disposed on or below a rolling track (1") of a lane (1') perpendicularly to the longitudinal axis thereof.
4. Device according to any one of claims 1 and 2, characterised in that it comprises a single rectangular loop (2) for the two rolling tracks (1") of a lane (1').
5. Device according to any one of claims 1 to 3, characterised in that it comprises an assembly of two loops (2), constituted by a same conductive wire connected to a single detector (3) and of which each is disposed on or below one of the two rolling tracks (1") of a same lane (1') of the roadway (1).
6. Device according to any one of claims 1 to 3, characterised in that it comprises an assembly of at least two loops (2), each connected to a separate electromagnetic detector (3) and disposed in an alignment perpendicular to the axis (X) of the roadway (1) or to the direction of travel of the vehicles, said loop assembly (2) extending either on or below a single rolling track (1") of the lane (1'), or over substantially the entire width of the roadway (1).
7. Device according to any one of claims 1 to 2, 5 and 6, characterised in that the loop or loops (2) have a shape other than rectangular, such as for example a parallelogram, square, round, oval or elliptical shape and in that, in the case of an arrangement, alignment or assembly of several loops (2), the loops (2) are either separated or are tangential or secantal to each other.
8. Device according to any one of claims 1 to 7, characterised in that the loop or loops (2) are secured to one or more flexible and strong sheets or strips, which may be woven, have identical or complementary characteristics and consist for example of rubber, plastic, synthetic or resinous products, these sheets or strips being adapted to sandwich the wires of the turns of the loop or loops (2), to have a self-adhesive face permitting adhesion of the loop or loops (2) to the roadway (1) and themselves consisting of marking strips, for example stop lines, "give way" lines, centre lines or side lines or the like.
9. Device according to claim 8, characterised in that the loop or loops (2) are secured to one or more sheets constituting temporary supports, open-worked as the case may be, disposed on the roadway (1) and secured together by a localised or overall coating penetrating the openings, the sheets being adapted to be biodegradable or soluble by a component in particular of the binder of the coating or by heat.
10. Device according to any one of claims 1 to 9, characterised in that it is associated or integrated with another system for the detection and reception of data relating to the vehicles such as for example an electromagnetic loop of large size, a piezo-electric detector, a resistive detector, a piezo-polymeric detector, an optical detector, a hyperfrequency detector or an ultrasonic detector, so as to receive supplemental data relating to the vehicle to be studied, permitting further refinement of the identification of said vehicle.
11. Device according to any one of claims 1 to 10, characterised in that it comprises a loop (2) of small size in the direction of travel of the vehicles, disposed in a large loop (2'), the two loops (2 and 2') being made of the same conductive wire connected to a same electromagnetic detector (3).
12. Process for the detection, analysis and classification of vehicles or wheeled machinery using the device according to any one of claims 1 to 11, consisting in noting the electromagnetic influences associated with the passage of a vehicle, by means of at least one electromagnetic loop (2), disposed on or within the roadway (1) and having a small dimension in the direction of travel of the vehicles or of the axis (X) of the roadway (1), characterised in that it consists, by means of at least one loop (2) whose dimension (1) or width is substantially equal to the width of the bearing surface on the ground for the vehicles to be analysed, in noting first the opposite variations of voltage and/or frequency of an alternating signal moving within the loop or loops (2) associated, on the one hand, with the wheels of the vehicles and, on the other hand, with the body or chassis of said vehicles, in processing the signal proportional to said variations, in producing a signal indicating the number and position of the wheels relative to each other and relative to the body of the vehicle, in identifying the precise nature of the analysed vehicle and in classifying it within predetermined categories, based essentially on the number and longitudinal arrangement of the wheels or of the axles, and in storing the received data for a determined period of time for their ultimate use, for reading in situ and/or remotely, with optional transfer of its contents.
13. Process according to claim 12, characterised in that it consists in noting the variation of electromagnetic magnitudes or frequency or voltage of an alternating signal moving within the loop or loops (2), during passage of a vehicle over the loop or loops (2), according to the electromagnetic influence, in particular as to the inductance of the loop or loops (2), of the body or the chassis of the vehicle, on the one hand, and the corresponding wheels, on the other hand.
14. Process according to any one of claims 12 and 13, characterised in that it consists, by means of several independent loops (2) disposed perpendicularly to the axis (X) of the roadway (1) and each producing its own signal, in noting transversely the position of one or more single or double wheels of a given vehicle, and therefore the position thereof on the lane (1'), and in scanning said vehicle by longitudinal sections, thereby permitting reconstitution of the imprint or the magnetic signature of said vehicle allowing comparatively precise identification thereof.
15. Process according to any one of claims 12 to 14, characterised in that it consists in also determining the length of the body or of the chassis and the distances between the roadway (1) and the bottom of the chassis between the axles, on the one hand, and to the front and rear of the axles, on the other hand.
16. Process according to any one of claims 12 to 15, characterised in that it consists in the supplemental use of an ultrasonic detector, to determine the profile or silhouette of the vehicle to be analysed.
17. Process according to any one of claims 12 to 16, characterised in that it consists in the supplemental use of an electromagnetic loop (2') of large size, associated with a loop (2) constituted by the same conductive wire, to determine, also by analysis of the received signal, the speed of travel and the length of detected vehicles.
18. Process according to any one of claims 12 to 17, characterised in that it consists first of installing the loop or loops (2), in the roadway (1) by means of a saw permitting suitable imprints or cut-outs to be obtained in said roadway (1).

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