EP0767946B1 - Vehicle detecting device - Google Patents

Abstract

A vehicle detecting device has at least one current-conducting loop preferably laid in the ground and connected to an evaluation unit for detecting current changes in the conducting loop caused by the presence of metallic vehicle components above the conducting loop. A receptor (9) contactlessly collects data from an identification unit (6) provided in or on the vehicle (5). The conducting loop (S1, S2, S2) acts as an antenna for the receptor (9).

Description

The invention relates to a device for detecting and checking vehicles, especially in parking garages or toll stations.

GB-A 2169173 describes a device for the detection and control of Vehicles, especially known at toll stations, which have been laid in the carriageway Has conductor loop with an adjustable capacitor device on a Resonance frequency is tuned and fed by an oscillator with alternating current becomes. The conductor loop is connected to an evaluation unit, which by the Presence of a vehicle certain changes in inductance of the conductor loop recognizes, as well as with a transceiver for contactless Communication with an identification unit arranged on or in the vehicle connected. The evaluation unit and the transmitting / receiving device consist of essentially the same hardware components and can be accessed via a Current detection device for the conductor loop fed with a fixed frequency determine the presence of a vehicle and after detection of the presence of a vehicle using the conductor loop as antenna data with the Replace identification unit, depending on which a signal for the vehicle is controlled. The data is transferred between the vehicle and the transceiver essentially with the frequency with which the conductor loop for the presence detection is fed. The data transfer between the transceiver and the vehicle, on the other hand, takes place with a much higher one Frequency.

The object of the invention is to provide such a device in which to detect and Control of vehicles a double use of the conductor loop is done with one to create the simplest possible structure, so that existing systems without large structural interventions can be retrofitted.

This is according to the invention by the features specified in claim 1 reached.

The system of the invention can be used, for example, when entering and exiting use a parking garage or underground car park.

For this, it is possible, for example, that a microprocessor automatically does the whole Facility initially operates in the first mode to ensure presence metallic vehicle components. As soon as this presence is recognized the microprocessor switches over the electronically implemented one, for example Switch automatically switches to the second operating mode and tries one Read identification unit. If an identification unit is attached to the vehicle the data can then be processed further, for example with a Authorization database can be compared. Is this not possible or none Authorization is available, a parking ticket will be issued. After passing The microprocessor can then switch this vehicle back into the first operating mode switch back.

Further advantages and details of the invention will become apparent from the following Description of the figures explained in more detail.

Fig. 1 schematisch die Schranken- und Parkscheinausgabeeinheit an der Einfahrt eines Parkhauses oder einer Tiefgarage mit drei hintereinander verlegten Leiterschleifen,

Fig.2 einen Vertikalschnitt durch eine im Boden verlegte Leiterschleife mit herannahendem Fahrzeug, das mit einer Identifikationseinheit ausgestattet ist,

Fig.3 schematisch ein einfaches Ausführungsbeispiel zur Realisierung der erfindungsgemäßen Idee,

Fig.4 in einem schematischen Blockschaltbild ein Ausführungsbeispiel der erfindungsgemäßen Einrichtung, sowie eine zugehörige Identifikationseinheit,

Fig. 5 den Stromverlauf in einer der Gleiterschleifen der Fig. 4 in verschiedenen Fahrzeugpositionen bzw. verschiedenen Betriebsarten der erfindungsgemäßen Einrichtung.

It shows:

1 schematically shows the barrier and parking ticket issuing unit at the entrance to a parking garage or underground car park with three conductor loops laid one behind the other,

2 shows a vertical section through a conductor loop laid in the ground with an approaching vehicle and equipped with an identification unit,

3 schematically shows a simple exemplary embodiment for realizing the idea according to the invention,

4 shows a schematic block diagram of an embodiment of the device according to the invention and an associated identification unit,

5 shows the current profile in one of the slide loops of FIG. 4 in different vehicle positions or different operating modes of the device according to the invention.

In Fig. 1 the usual arrangement in parking garages or underground garages is shown. in the Three conductor loops S1, S2, S3 are laid on the floor. These capture over a in the Column 2 schematically shown evaluation unit 3, the presence of metallic Vehicle components above the conductor loops S1, S2, S3. If one If the vehicle moves over loops S1, S2, a parking ticket is issued and the barrier 4 opens. Loop S3 can be used to determine whether that Vehicle has left the area of the barrier in order to prevent it from using collided with the vehicle when closing. Via the loops S1, S2, S3 and the Evaluation unit can essentially only the presence of metallic Vehicle components and only record their structure to a limited extent. A actual identification of individual guest vehicles is therefore not possible.

In order to enable such identification without contact, the invention provides that an identification unit 6 is provided on vehicles 5, in the vehicle and / or driver-specific data are stored. According to the basic idea of The invention provides that the conductor loops S1, S2, S3 also act as an antenna Receiving device used to read the data of the identification unit 6 be (Fig. 2). The conductor loops are therefore used twice, once - by how previously common - just to detect the presence of metallic vehicle components and additionally as an antenna for reading the identification unit 6 on a vehicle 5.

A simple embodiment of the device according to the invention is schematic shown in Fig. 3, in which only one conductor loop S1 laid in the ground current-carrying conductor loops S1, S2, S3 with one connected to them Evaluation unit 3 is shown. This is used to record changes in the Current in the conductor loops, which are caused by the presence of metallic Vehicle components are caused above the conductor loops. It can So it can be detected whether a vehicle is above the conductor loops. In which A simple exemplary embodiment shown in FIG. 3 is now a changeover switch 7 provided, which can of course also be implemented electronically. This Switch 7 is controlled via a control line 8 when the evaluation unit detects that a vehicle is on the loops. Then the switch 7 goes to the in Fig. 3 shown position in a position in which he loops with the receiving device for reading the identification unit 6 on the vehicle 5. In In this position, the conductor loops thus act as an antenna for the receiving device 9. The receiving device 9 can now be shown schematically Read and read identification unit 6, which is actually above loop S1 for example, compare the read data with stored data. After this Reading process or a certain period of time can then switch 7 in again the position shown in Fig. 3 decrease. The one shown in Fig. 3 Embodiment can in principle be practically unchanged from a previous system continue to use. It is only by a switch 7 and a receiving device 9 added.

If the device according to the invention retrofitted to an existing system should be and of course even more so when it comes to reinstalling a complete system, it is favorable if the evaluation unit for Presence detection of metallic vehicle components and the (transmission and) Receiving device for communication with the identification unit essentially consist of the same hardware components. Basically the same hardware components which advantageously comprise a microprocessor, can then be simply in a first operating mode as an evaluation unit for presence detection metallic vehicle components and in a second operating mode as (transmit and) Receiving device for communication with the identification unit 6 on the vehicle use.

Such an embodiment is shown in FIGS. 4 and 5. The one shown there The device thus works both as an evaluation unit 3 for mere presence detection metallic vehicle components as well as a receiving device for reading the data stored in the identification unit 6.

The device shown in FIG. 4 has an oscillator 10 which, via a power amplifier 11, supplies the loops S1, S2, S3 shown schematically in the floor with alternating current of fixed frequency f ₀ . In the exemplary embodiment, this frequency is typically in the range of approximately 100-150 kHz. The conductor loops S1 to S3 can be operated in time-division multiplex operation via the control line 12 and the switch unit 13 in order to obtain more precise information about the vehicle position. In principle, however, the device would also work with a conductor loop S1, which is why only the conductor loop S1 is referred to below.

The inductance of the loop S1 and the capacitance of the capacitor device, denoted overall by 14, form a series resonant circuit which is tuned to the driver frequency f ₀ from the oscillator 10. In contrast to known free-swinging resonant circuits, which only run at their respective resonance frequency by means of a feedback amplifier, the oscillator 10 in the exemplary embodiment shown in FIG. 4 definitely specifies a fixed frequency. If the series resonant circuit S1, 14 is ideally tuned to this frequency f ₀ , a current with the maximum current intensity flows through the conductor loop S1 and the current detection device 15. Any detuning of the series resonant circuit S1, 14 against the frequency f ₀ brings about a reduction in the current intensity (amplitude of the alternating current). This is used to be able to use the current intensity detected in the current detection device 15 as a measurement signal. Via a filter device 16 and an analog-digital converter 17, the current value in digital form is thus available to the microprocessor 19 on the line 18 and can therefore be easily further processed digitally.

FIG. 5 shows an example of the time profile of the current intensity detected by the detection device 15. The maximum current (amplitude A1) is present in area A. There is no metallic vehicle component in the area of the loop S1 in this period. Together with the capacitor device 14, this is ideally matched to the fundamental frequency f _{0 of} the oscillator 10. If a metallic component of a vehicle now comes into the area of the loop S1, its total inductance changes, which detunes the resonant circuit and thus reduces the current flow S1 while the carrier frequency f ₀ remains the same. This is shown in area B. The current amplitude therefore drops to the value A2 when a vehicle is present. As soon as the microprocessor 19 recognizes this in the digital current signal 18, it controls the amplifier 11 in a suitable manner via the control line 20 in order to generate current pulses in the loop S1, as shown in area C. These current pulses or the transmitters caused thereby in the vicinity of the loop S1 are used to query the identification unit 6. The conductor loop S1 thus works in the area C as a transmitter antenna.

In the exemplary embodiment shown, the identification device has an antenna 21 and a capacitor 22. When the switch 23 is closed, it is possible via this circuit to provide the necessary supply voltage for the electronic logic circuit 25 after rectification in a rectifier 24. The identification unit 6 is thus “woken up” by the transmitter pulses from the conductor loop S1. Such battery-free identification units are basically already known to the person skilled in the art and therefore do not need to be described in detail. After “waking up” it is now a question of the identification unit 6 sending back vehicle-specific or driver-specific data which are stored, for example, in an E ² PROM 26. The logic circuit 25 receives this stored data and controls the switch 23 via the control line 27 in order to transmit the binary (0/1) -coded data. Each time the switch 23 is opened, the resonant circuit 21, 22 is interrupted and thus further dampens the amplitude of the current in the conductor loop S1 to a value A3, as shown in area D in FIG. 5. In this way, it is possible to transmit the data stored in E ² PROM 26 to the receiving device 9 in a contactless manner, the conductor loop S1 then functioning as a receiving antenna. If the receiving device 9 determines that it is not receiving any data, then the vehicle is not equipped with any (or a non-functioning) identification unit 6. In this case, the microprocessor 19 opens the barrier 29 via the amplifier unit 28 after it has issued a parking ticket via a parking machine (not shown). If the vehicle is equipped with a functioning data carrier (identification unit 6), the microprocessor 19 can check the read data for authorization with internally or externally stored data in a database and, in the event of a positive result, immediately open the barrier 29 without issuing a parking ticket. This enables vehicles with a valid identification unit to pass control stations quickly and easily, in particular barriers at the entrance to a parking garage or underground car park.

A particularly advantageous automatic adjustment of the resonant circuit consisting of the conductor loop S1 and the capacitor device 14 to the driver frequency f _{0 would have to be added} . It has been shown that the inductance of the conductor loop S1 varies due to external influences or moisture. By changing the capacitance of the capacitor arrangement 14, an optimal adjustment of the resonant circuit to the fixed driver frequency f ₀ can always be achieved. From time to time, the microprocessor can selectively switch on and off the schematically represented switches of the individual capacitors C1 to C5 via the control line 30 until the digital current value on line 18 becomes maximum. With the then available total capacitance of the capacitor device 14 (consisting of the capacitors C1 to C5 which can be selectively switched on and off) and the present inductance of the conductor loop S1, the resonant circuit S1, 14 formed is then ideally matched to the oscillator frequency f ₀ . In addition to the selective connection and disconnection of individual capacitors, it would in principle also be possible to use capacitors with adjustable capacitance, for example variable capacitors for the adjustment. In order to avoid mechanically moving components, however, the solution shown in FIG. 4 seems to be cheaper.

Claims (6)

1. An arrangement for detecting and controlling vehicles (5), in particular in car parks or at toll stations, comprising two or more conductor loops (S1, S2, S3) which are arranged in succession in the direction of travel and which are preferably laid in the roadway and which are tuned to a resonance frequency with a capacitor device (14) which is possibly adjustable in capacitance, which conductor loops (S1, S2, S3) are fed with alternating current by an oscillator (10) and are connected to an evaluation unit (3) which recognises changes in inductance of the conductor loops (S1, S2, S3) which are determined by the presence of a vehicle (5), wherein the conductor loops (S1, S2, S3) are connected to a transmitting/receiving device (9) for contact-free communication with an identification unit (6) arranged on or in the vehicle (5) which is present, wherein the evaluation unit (3) and the transmitting/receiving device (9) comprise substantially the same hardware components, in a first mode of operation they detect the change in the current strength due to the presence of a vehicle (5) by way of a current detection device (15) for the conductor loops (S1, S2, S3) which are fed with a fixed frequency, and after recognition of the presence of the vehicle (5) in a second mode of operation with the same frequency they detect data stored in the identification unit (6), in dependence on which data a barrier (29), a set of traffic lights or another signal for the vehicle (5) are controlled, and wherein the conductor loops (S1, S2, S3), by way of the attenuation of which the passage of the identified vehicle (5) can be detected, are connected to the evaluation unit (3) by way of a change-over switch (7), whereby the reception range of the transmitting/receiving unit is increased.
2. An arrangement according to claim 1 characterised in that the identification unit (6) has an electronic data store (26), for example an E²PROM, a transmitting unit (21, 22) for contact-free transmission of the stored data to the receiving device (9), a device (21, 22, 24) for producing a supply voltage for its electronic components (25, 26) from the field energy of the conductor loop (S1, S2, S3) and an oscillating circuit (21, 22) which can be interrupted by way of a switch (23), wherein the switch (23) is controlled by an electronic control unit (25) in dependence on stored data.
3. An arrangement according to claim 1 or claim 2 characterised in that the identification unit (6) is mounted externally on the vehicle (5), preferably at the underside thereof.
4. An arrangement according to claim 1 characterised in that connected on the output side of the current detection device (15) is an analog-digital converter (17) for producing a digital current strength value.
5. An arrangement according to one of claims 1 to 4 characterised in that the capacitor device (14) includes two or more mutually parallel capacitors (C1-C5) which can be selectively optionally switched on and off by way of a switch unit to adjust the overall capacitance.
6. An arrangement according to claim 5 characterised in that there is provided an adjusting device which is preferably embodied by a programmed microprocessor (19) and which - preferably at regular intervals of time - automatically adjusts the capacitance of the capacitor device (14) until the current strength is at a maximum when a vehicle is not present.

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