IE62986B1 - Method and apparatus for monitoring the displacement of objects, and in particular of motor vehicles - Google Patents

Abstract

Vehicles are provided with cells (P1, P2) embedded in one of their main outer surfaces, but invisibly and at an indeterminable point. These cells are able to passively define, without individual electrical supply, a remotely readable unique code associated one-to-one with the vehicle. Identifying information in connection with some at least of the unique codes is recorded in at least one reference file (F5). Obligatory transit routes are each provided with a detector (L3) able to read on each vehicle the code defined by the cell(s) which it carries, as well as processing units (04) able to search for whether each code read is to be found in the reference file, and to store the result of this search. <IMAGE>

Description

The invention relates in particular to the monitoring of the movement of automotive vehicles, w in particular in order to act as a deterrent against the theft of these vehicles. Various means used as a deterrent against car theft are already known. One of these means consists in making markings over all or some of the windows and windscreens of the vehicle. In order to render the vehicle unrecognisable, the thief is then forced to change all the windows and windscreens which is a lengthy and costly operation.

It has also been proposed to provide automotive vehicles with various types of anti-theft devices.

Currently it is considered necessary to provide a number of devices or means of different types if it is really desired to deter thieves from stealing a vehicle.

Finally, a process is known (from Robert Hauslen’s article The Promise of Automotive Vehicle Identification, IEEE transactions on vehicular technology, vol. VT-26, No. 1, February 1977) for monitoring the movement of objects, in particular automotive vehicles, which consists in reading £ / Ο η £ Ο ζ. ir11 υ Ο remotely one or more markings on the vehicle which can identify it completely.

Such a process is of the type in which each 5 vehicle is made to pass along a compulsory lane.

At least some of the vehicles are provided with at least one cell embedded in one of the main external surfaces but invisibly and at a point which cannot be determined, the cell or cells being suitable for defining passively, without their own electrical supply, a unique code which can be read remotely and is uniquely associated with the vehicle, each cell comprising a receiver loop or antenna; finally, each lane is provided with at least one sensor which can read from each vehicle the code defined by the cell or cells which it carries, as well as processing means, the sensor comprising a looped antenna emitting an electromagnetic beam at a predetermined frequency.

This process, based in particular on microwave technology, uses electromagnetic transmission at a second harmonic frequency of the emission frequency in order to read the identity code, and thus proves complex to implement.

The present invention proposes an anti-theft deterrent process of an original type.

In accordance with the principal feature of the invention, each cell modulates the loading of its receiver loop or antenna according to pulses representing its own unique code when its receiver * loop or antenna is coupled with a looped antenna of a sensor so as to perform modulation by absorption of the waves emitted; the sensor reads the unique code by using variations in the current surge in its looped antenna; identification data relating to at least some of the afore-mentioned unique codes are recorded in at least one reference file and the processing means can search to discover whether each code read is in the reference file and store the result of this search.

In particular, this enables stolen vehicles to be identified and followed.

The compulsory lane through which the vehicle must travel may be a simple traffic lane or, preferably, a point which vehicles have to pass compulsorily one at a time. In particular the « lane may therefore be defined as a gantry where the vehicle can be forced to pass through at average or low speed.

Most advantageously, the sensor reads the cell by means of waves, in particular electromagnetic waves, and preferably long waves.

In accordance with a further aspect of the invention, each vehicle is provided with at least two cells which together can define the unique code.

As a variant, the unique code may be applied to one and another of the cells. However the vehicle will only be recognised as genuinely possessing the code if it is read twice on the two cells.

Furthermore, the two cells may be located at different points on the vehicle.

In accordance with a further feature of the invention, at least one file is produced for the codes being validated and one file is produced for the codes to be monitored, such as those of stolen vehicles.

In a particular embodiment, the lane comprises a gantry equipped with a barrier of which the opening is dependent on the result of the comparison of the vehicle code with the reference file.

However it is also possible to provide a simple means for recording the passage of the vehicle without attempting to stop the latter.

It is likewise advantageous for the sensor to be embedded in a wall of the gantry or in the ground under the traffic lane.

The object of the invention is likewise a device enabling the above-mentioned process to be performed, comprising on board at least some vehicles a passive cell comprising a receiver loop or antenna which can respond at a distance to a wave emission predetermined by a unique code, associated uniquely with the vehicle, and at least one sensor comprising an embedded looped antenna for producing the emission of waves at a predetermined frequency and detecting the unique code, characterised in that each cell comprises means for modulating the loading of its receiver loop or antenna according to pulses representing its own unique code when its receiver loop or antenna is coupled with the looped antenna of the sensor so as to perform modulation by absorption of the waves emitted; and in that the sensor comprises means for utilizing the variations in the current surge in its looped antenna in order to read the unique code.

Further features and advantages of the invention will appear from the following detailed description and the attached drawings, in which: - Figure 1 is a schematic diagram of a device implementing the invention; - Figures 2 to 4 are pictorial diagrams enabling the various applications of the process according to the invention to be better understood; and - Figure 5 is a preferred variant of the device according to the invention.

In Figure 1, the reference V designates a vehicle The vehicle is provided with two coded plates P1 and P2 which in principle are the same shape, which may be round as shown at P1 or even rectangular as shown at P2.

In addition. Figure 1 shows the plates appearing obviously on the side of the vehicle.

It is particularly advantageous if these plates are located below the vehicle.

The plates may be made from a material such as polyvinyl chloride, secured by three pop type rivets (registered trade mark) for example, currently used to secure registration plates.

Electronic coding circuits are provided in the plates P1 and P2 such that they can be identified by means of electromagnetic waves, as will be seen hereinbelow.

A reading device is implanted such that it can read the plates P1 and P2. This reading device is illustrated at L3 in Figure 1.

As indicated at L10, L11, L12 and L13 in Figure 2, the reader (or at least its antenna) is in principle embedded in the ground, below a compulsory passage point.

During the initial experiments, it was envisaged that the reader L3 and its antenna would, for example, be those of the XS hands free access monitoring assembly type sold by the ZETTLER company, La Garenne Colombes, France, or some other similar equipment.

It was noticed that this apparatus can read passive cells at a distance without any energy source being implanted in this cell. This cell, therefore, cannot be detected.

In addition, as soon as it is embedded in the 5 ground, the antenna is no longer visible and can no longer be sabotaged.

However, it has emerged that the afore-mentioned device is sensitive to the variations created in these operating conditions by the passage of a vehicle.

It is for this reason that it is currently preferred to use the device shown in Figure 5.

An oscillator 51 operating at 128 kHz for example supplies an amplifier 52. The output of the amplifier 52 is connected by means of the primary of a current transformer 53 to a variable capacitor 54 followed by a coil 55 which is a loop buried in the ground. The variable capacitor 54 enables tuning to be performed so as to increase the radiated power as much as possible.

The secondary of the current transformer 53 is connected via a low-pass filter 56 comprising an amplitude sensor to the inverting input of the amplifier 52.

The cut-off frequency of the low-pass filter 56 is selected such that the correction signal applied to the amplifier 52 enables it to maintain the signal at a constant level irrespective of whether or not a vehicle is above the loop 55.

The assembly likewise comprises a connection to an operating circuit 58. This connection can start at the input of the filter 56 or can even be taken from the power supply to the amplifier 52.

The sensor is formed by a coil 60 incorporated in all vehicles. The coil 60 passes into the position where it is coupled to the buried loop 55.

This coil 60 can be provided with a ferrite core 61 and can likewise be associated with a capacitor 62, the two latter additions not being absolutely necessary.

The voltage available at the terminals of the coil 60 is used in a supply circuit 63 which supplies the necessary voltages to the other various components of the receiver on board the vehicle.

Figure 5 shows that the power supply 63 is used in particular for the operation of an EPROM (electrically programmable read only memory) bearing the reference 64.

A clock frequency is established by a circuit 65. It is synchronised with the frequency of the signal received at 128 kHz, available at the terminals of the coil 60. Synchronisation may be achieved as a result of the fact that the clock signal is taken directly from the signal received, or as a result of the fact that a separate clock source is controlled by the rate of the signal received, in terms of frequency and phase.

In this way, the memory 64 provides binary code data which are applied to a loading circuit 66 which can modulate the current surge caused by the coil 60, relative to the buried coil 55.

Currently it is preferable if the current surge is modulated by acting on the damping of the coil 60. However, as a variant, it is also possible to envisage that the variation is achieved by shifting the contingent resonant frequency of the circuit defined by the loop 60 and the capacitor 62 (for example).

In a particular embodiment, the code is emitted at a frequency of 64 kHz.

The interference created by the passage of the car is at a lower frequency. Consequently, the cutoff frequency of the filter 56 is far lower than kHz.

One of the principal advantages of the circuit described above is that, firstly, it is possible to compensate for the interference caused by the passage of the vehicle itself, and secondly, in the emission circuit there is a signal modulated by the code which is representative both of the frequency and of the phase.

This signal can be utilized by the circuit 58, after a possible change of frequency, by performing a numerical Fourier transformation or by two frequency changes enabling the return signal, modulated under the effect of the code, and the signal initially emitted by the oscillator 51, suitably divided according to frequency, to be intercorrelated.

The person skilled in the art will understand that it is thus possible to recover signals which to a large extent are concealed in the noise.

In the above description, there is envisaged a code modulated by a single frequency, i.e. the 1 bits correspond for example to the variation in the loading of the coil 60 whilst the 0 bits do not correspond to any variation. It will be appreciated that it is possible for the 1 bits to be transmitted by action at a given rate on the loading of the coil 60, whilst the 0 bits are transmitted by action at another rate on the loading of the same coil 60. It can be arranged such that the two rates do not have any common harmonic at least in the band used.

This arrangement shown in Figure 5 has a further advantage; owing to the fact that variations to be imposed by the circuit 66 on the coil 60 are very rapid, power necessary for supplying the receiver circuits is always available at the circuit 63.

The cell can have a diameter of 56 mm for a thickness of approximately 1.5 mm. Made from polyvinyl chloride and secured by three pop rivets, as stated above, the cell can be covered with a coating such as that known by the name of Blackson. It is then completely invisible and cannot be detected underneath the vehicle.

Furthermore, as the cell is not necessarily directional, it is not obligatory to secure it at a precise angle relative to the antenna which the reader comprises. As a variant, the cell can be embedded in plastics material.

The operating principle is as follows: - the reading antenna L3 emits an electromagnetic beam, at a frequency of 120 kHz for example, in the general direction where the cells of a vehicle can be seen; - each cell absorbs and modulates by pulses the part of the beam striking it as a function of its own code; - the reader L3 detects the pulse variations in . the energy transmitted resulting therefrom; owing to the difference with respect to the initial signal, the pulsed absorption of the energy by the cell enables its code to be retrieved and thus identified.

The frequency of the radiation selected, i.e. 120 kHz, permits sufficient propagation in the air.

It will be appreciated that any other frequency enabling propagation of this type to be attained can be used. ν 25 Likewise, the implementation of the invention is not restricted to longwave radiation. Other types of radio waves can be used, in particular X-rays or even light rays.

The cells P1 and P2 can each bear part of the code identifying the vehicle. It thus the concatenation of the two codes, i.e. of the two reading processes, which provides a single code corresponding uniquely with the vehicle in question.

In accordance with a variant, each of the two cells P1 and P2 comprises the unique code peculiar to the vehicle. If the reading process only provides a single code for a single cell, the missing cell is assimilated with an anomaly, which leads it to be supposed that the vehicle is in breach of the law (in the widest sense of this term), i.e. for example if it is a stolen vehicle.

Tests performed have demonstrated that the above device did not present any problem as regards constraints or particular interference.

The readers such as L3 can have a surface area of 0.80 m x 0.80 m. A relatively large tolerance is available as regards the angle between the viewing direction of the reader and the expected positions of the cells. Reading may be performed for a distance ranging from 0.70 to 1 m between the antenna of the reader L3 and the cells P1 and P2.

The signals provided by the above reader L3 may be digital signals. If necessary, they are converted into signals which can be understood by a data processing system such as the computer 04 shown in Figure 1.

This computer may then cooperate with files designated F5 in Figure 1 and comprising a central file for example accompanied by a monitoring stoppage file if, for example, the vehicle owner were no longer to pay a rental charge associated with the monitoring of the two plates carried by his/her vehicle.

In the preferred application, the central file can be or comprise a stolen vehicle file.

Figure 2 illustrates better the applications according to the invention.

The central file F5 can firstly be filled with data supplied by a customer 60 whose vehicle has been stolen.

This file may also be filled with data supplied by approved centres 65.

The central file can then communicate with the police departments 61, 62, the insurance department or other departments 64.

The compulsory passage points where the invention can be used are, for example, toll points 10, the 1θ entrances and exits of car parks 11 (in particular the entrances), the entrance to pounds 12 and the entrance to garages 13. In each case the area covered by the sensor or reader L is illustrated at L10, L11, L12 and L13 respectively.

A local data processing device such as 04 (not illustrated in Figure 2) exchanges data between each of the readers L10 to L13 and the central file F5.

The code data defined by the reader L3, in data processing language, may either be stored in the reader or transmitted remotely in order to be stored in a central site for example where the file F5 is located. Transmission may be performed in various ways such as telex, telephone lines which may or may not be switched, networks, etc.

In the simplest embodiment of the invention, each vehicle, equipped with plates or cells, and passing in front of a reader is systematically and automatically read.

A sub-file of vehicles indicated as being stolen to the central file is transmitted (Figure 3) to each monitoring station (10, 11, 12, 13, Figure 2).

Hitherto, everything occurs by the simple comparison of the code read with codes recognised as being allocated to a stolen vehicle.

If the comparison indicates a theft, then far more detailed data which can be provided at the central file F5 are taken into consideration: time and location of the passage of the vehicle, exact identity of vehicle (registration, chassis number), as well as the owner’s details.

In general, when vehicles are moving about on public highways, civil liberty is thus prevented from being undermined since all the data are only available in the central file F5 where they can be protected.

Only the codes are transmitted to the monitoring station.

A variant (Figure 4) furthermore consists in simply transmitting the codes read from the monitoring station to the central file, for given applications.

Furthermore, it may be imagined that particular garages, for private or public use, can be provided with a coding system of this type for their season ticket holders, for example. In this case, the central file may be in the same location as the garage.

It will be appreciated that the implementation of the invention is not restricted simply to stolen vehicles. For example it would be possible to provide for custom controls, controls to check whether an insurance policy exists, which would be implemented by plates according to the invention, or even controls to check whether road tax has been paid, and more generally any operation which can be associated uniquely with a vehicle (automatic payment of tolls on motorways, urban parking for example).

Suitably miniaturised, a device according to the invention can also be used to control the opening of vehicle door locks, and/or unlock their steering anti-theft systems. As above, a file enables the code number of each system to be held and linked with the chassis number of the vehicle in question.

The equivalent of the reader is disposed at a device controlling the central locking of the vehicle, preferably located in the driver's door, and/or on the steering anti-theft system. The equivalent of the door key is the cell according to the invention. However the reciprocal arrangement may also be envisaged.

Claims (16)

1. Method of monitoring the movement of objects, in particular automotive vehicles, of the type in which each vehicle is made to pass along a compulsory lane, at least some of the vehicles being provided with at least one cell (P1, P

2. ) embedded in one of their main external surfaces but invisibly and at a point which cannot be determined, the cell or cells being suitable for defining passively, without their own electrical supply, a unique code which can be read at a distance and associated uniquely with the vehicle, each cell comprising a receiver loop or antenna (60), each lane being provided with a sensor (L3) which can read from each vehicle the code defined by the cell or cells which it supports, as well as processing means (04), the sensor comprising a looped antenna (55) emitting an electromagnetic beam at a predetermined frequency, characterised in that each cell modulates the loading of its receiver loop or antenna (60) according to pulses representing its own unique code when its receiver loop or antenna (60) is coupled with a looped antenna (55) of a sensor so as to perform modulation by absorption of the waves emitted; in that the sensor reads the unique code by using the variations in the current surge in its looped antenna (55); in that identification data relating to at least some of the unique codes are recorded in at least one reference file (F5); and in that the processing means can search to discover 5 whether each code read is in the reference file and store the result of this search, which in particular enables stolen vehicles to be identified and followed. 10 2. Method according to Claim 1, characterised in that the sensor reads the cell via waves, in particular long waves.

3. Method according to either of Claims 1 15 and 2, characterised in that each vehicle is provided with at least two cells (P1, P2) which together can define the said unique code.

4. Method according to Claim 3, 20 characterised in that the two cells (P1, P2) are located at different points on the vehicle.

5. Method according to any one of Claims 1 to 4, characterised in that at least one file is 25 produced for the codes being validated and one file is produced for the codes to be monitored, such as those of stolen vehicles.

6. Method according to any one of Claims 1 to 5, characterised in that the lane (13) A comprises a gantry equipped with a barrier, of ' which the opening is dependent on the result of 5 the comparison of the vehicle code with the reference file.

7. Method according to any one of the preceding claims, characterised in that the sensor 10 (L10, L11, L12, L13) is embedded in a gantry wall or in the ground.

8. Method according to any one of the preceding claims, characterised in that the sensor 15 (L10, L11, L12, L13) is located at a point where the vehicle is forced to drive at an average or low speed.

9. Device enabling the method according to 20 any one of the preceding claims to be performed, comprising on board at least some vehicles a passive cell comprising a receiver loop or antenna (60) which can respond at a distance to a wave emission predetermined by a unique code, * 25 associated uniquely with the vehicle, and at least one sensor comprising an embedded looped antenna for producing the emission of waves at a predetermined frequency and detecting the unique code, characterised in that each cell comprises means (66, 62, 64) for modulating the loading of its receiver loop or antenna (60) according to pulses representing its own unique code when its receiver loop or antenna (60) is coupled with the looped antenna (55) of the sensor so as to perform modulation by absorption of the waves emitted; and in that the sensor comprises means (58} for utilizing the variations in the current surge in its looped antenna (55) in order to read the unique code.

10. Device according to Claim 9, characterised in that modulation by absorption is performed by damping the receiver loop or antenna (60) of the passive cell.

11. Device according to Claim 9, characterised in that modulation by absorption is performed by shifting the frequency of the receiver loop or antenna (60, 62) of the passive cel 1.

12. Device according to any one of Claims 9 to 11, characterised in that the value 1 and the value 0 of a code bit are transmitted by pulse sequences at a first speed for the value 1 and at a second speed, different from the first, for the value 0.

13. Device according to any one of Claims 9 to 12, characterised in that the emission means comprise means (56) for compensating the variations in the looped antenna charge when a vehicle passes.

14. Device according to any one of Claims 9 to 13, characterised in that it is used for unlocking a door lock or a steering anti-theft device.

15. A device according to Claim 9 for monitoring the displacement of motor vehicles substantially as hereinbefore described with reference to the accompanying drawings,

16. A method according to Claim 1 of monitoring the displacement of motor vehicles substantially as hereinbefore described with reference to the accompanying drawings.